Winter, Spring, and Summer – All at the Same Time

The current weather pattern across the country is one that is fairly typical of Spring. However, the results of that pattern are wintry weather in the Rockies and summer-like weather in the East. In the battlezone between the two there is plenty of severe weather, which is fairly typical of Spring.

500mb analysis map from 8am EDT May 17, shows a ridge of hgh pressure in the East and a trough of low pressure in the West. Image provided by College of DuPage.
500mb analysis map from 8am EDT May 17, shows a ridge of hgh pressure in the East and a trough of low pressure in the West. Image provided by College of DuPage.

An upper-level low pressure area will move out of the Pacific Northwest and into the nation’s midsection over the next few days. While one surface low pressure area moves into the Upper Midwest today, a second one will develop east of the Rockies and move into the Plains states on Thursday. With cold air moving in behind the system, and warm, moist air flowing northward from the Gulf of Mexico ahead of it, strong to severe thunderstorms are likely again today, Thursday, and Friday across the Plains states.

Severe weather has plagued the nation’s midsection for the past few days, with over 500 reports of severe weather between Monday and Tuesday. Nearly 30 tornadoes were reported, along with hail as large as softballs, and hundreds of reports of wind damage from gusts as high as 85 mph.

GFS model snowfall forecast through Saturday morning for the Rockies. Image provided by WeatherBell.
GFS model snowfall forecast through Saturday morning for the Rockies. Image provided by WeatherBell.

Behind the low pressure area, a late-season snowstorm is expected across the Rocky Mountains. Heavy snow will continue across portions of Montana and Idaho today, spreading into Wyoming and Colorado for Thursday into Friday. Across the higher elevations, totals of 1-3 feet are expected, which will keep the ski season going for a while longer. Snow may also spread into the High Plains of eastern Colorado and western Nebraska, with some minor accumulations possible. In Denver, it looks a couple of slushy inches may fall, though at least 1 model is forecasting much heavier amounts. In a normal year, Denver averages 1.7″ of snow, and the city has seen measurable snow during the month of May in 11 out of the last 16 years, so snow in May is not uncommon, though a heavy snowstorm, if it materializes, would be. Denver has only received 10 or more inches of snow in the month of May 6 times in a 135 years of records, with a record total of 15.5″ set back in May of 1898.

Record high temperatures are expected to be broken across the Northeast on Thursday. Image provided by WeatherBell.
Record high temperatures are expected to be broken across the Northeast on Thursday. Image provided by WeatherBell.

Meanwhile, in the East, an early taste of summer is ongoing, thanks to a ridge of high pressure aloft, and a surface high pressure area off the East Coast. Temperatures soared into the 80s and lower 90s on Wednesday, setting several records, but the hottest day for many locations will be Thursday. High temperatures will climb into the lower to middle 90s in many locations, likely breaking records across much of the region. When you combine the heat with dewpoints well into the 60s, it will definitely feel like a mid-summer afternoon across the region. A cold front will move through the area of Friday, possibly triggering a few showers and thunderstorms, but also sending temperatures back to where they should be in the middle of May.

 

Severe Weather in the South Today, Bigger Outbreak Friday?

Severe weather is likely across portions of the Gulf Coast and Mississippi Valley today, but another, perhaps more widespread, outbreak is possible at the end of the week.

Surface analysis as of 7am CDT Wednesday April 26. Image provided by NOAA.
Surface analysis as of 7am CDT Wednesday April 26. Image provided by NOAA.

 

A strong cold front is moving into the Mississippi Valley and Texas this afternoon, and it is helping to trigger strong to severe thunderstorms across portions of the region. Ahead of the front, temperatures are into the 70s and lower 80s, with dewpoints in the upper 60s and 70s, so there’s plenty of warm, moist air in place. Behind the front, temperatures quickly drop into the 50s and 60s. Thunderstorms will continue to develop in the unstable airmass ahead of the front, with some of the storms containing large hail, heavy downpours, damaging winds, and possibly some tornadoes. Earlier this morning, some storms produced baseball-sized hail and wind gusts in excess of 70 mph in portions of Missouri, Arkansas, and Oklahoma. The threat should start to diminish across the region as we head into the overnight hours.

A more significant severe weather outbreak is possible later Friday into Saturday from the Southern Plains and Texas into portions of the Mississippi and Tennessee Valleys. Low pressure will move out of Texas and head northward, drawing warm moist air northward from the Gulf of Mexico once again. North and west of the system, much cooler air will be in place (more on that in a moment).

Models are showing that a very unstable airmass will be in place across Texas and the Lower Mississippi Valley Friday afternoon. Image provided by Pivotal Weather.
Models are showing that a very unstable airmass will be in place across Texas and the Lower Mississippi Valley Friday afternoon. Image provided by Pivotal Weather.
Models are showing that a very unstable airmass will be in place across Texas and the Lower Mississippi Valley Friday afternoon. Image provided by Pivotal Weather.
Models are showing that a very unstable airmass will be in place across Texas and the Lower Mississippi Valley Friday afternoon. Image provided by Pivotal Weather.

 

As low pressure rides along the boundary between the two airmasses, it will help to trigger strong to severe thunderstorms across the region. The threat will continue into the overnight hours Friday night, shifting into the Mississippi and Tennessee Valleys on Saturday as the system continues to progress northeastward. Some of the storms may produce torrential downpours that could trigger flash flooding, large hail, damaging winds, and tornadoes.

Portions of the Mississippi Valley could received 5-10 inches of rain between  Wednesday and Sunday. Image provided by WeatherBell.
Portions of the Mississippi Valley could received 5-10 inches of rain between Wednesday and Sunday. Image provided by WeatherBell.

 

Behind the storm, as colder air settles into the region, a different threat is evolving – heavy snow. While it’s getting late in the season, heavy snow is not uncommon in the Central and Southern Rockies at this time of year. Some of the higher elevations in Colorado and New Mexico could receive 1-2 feet of snow Friday into Saturday. East of the Continental Divide, especially in the High Plains, snow is also possible, especially from eastern Colorado and western Kansas into portions of the Oklahoma and Texas Panhandles. In Denver, there is still a big question as to whether to precipitation falls mainly as rain, snow, or a wintry mix. Some snow accumulation seems likely at this point, but it’s still a little too early to tell whether there will be heavy snow in the city itself.

GFS models forecast for snowfall through Sunday morning across the Plains and the Rockies. Image provided by WeatherBell.
GFS model forecast for snowfall through Sunday morning across the Plains and the Rockies. Image provided by WeatherBell.

 

Severe weather outbreaks are not uncommon at this time of year. In fact, from late March into early May is when they are most likely. The largest tornado outbreak on record occurred 6 years ago this week. Between April 25 and 28, 2011, a total of 362 tornadoes were observed from Texas to New York and portions of southern Canada, resulting in 324 fatalities, 317 of them on April 27, the most active day.

Map showing tracks of all 362 tornadoes from the April 2011 "Super Outbreak". Image provided by Encyclopedia Brittanica.
Map showing tracks of all 362 tornadoes from the April 2011 “Super Outbreak”. Image provided by Encyclopedia Brittanica.

From Record Highs to Blizzard Conditions

Much of the nation’s midsection has been enjoying temperatures more typical of April than February for the past week, with a few hundred record high temperatures broken. That is about to change, as Mother Nature will remind the region that is still February.

Numerous record highs are expected across the Plains and Midwest for one more day. Image provided by WeatherBell.
Numerous record highs are expected across the Plains and Midwest for one more day. Image provided by WeatherBell.

One more warm day is expected today, with highs well into the 60s and 70s likely setting more records. However, a cold front will sweep across the region, bringing an end to the record heat, and setting the stage for a snowstorm.

The low pressure system that brought more rain to California over the past couple of days will head eastward, bringing some snow into the Rockies today. As that system moves into the Plains on Thursday it will start to strengthen, drawing moisture northward from the Gulf of Mexico while cold air flows southward on the backside of the storm into the Northern Plains. Where these airmasses meet, snow will develop across the Central Plains states. The snow will be accompanied by winds of 20-30 mph, gusting to 40 mph or more at times, resulting in near-blizzard conditions across portions of South Dakota, Nebraska, southeastern Wyoming, and eastern Colorado on Thursday.

More than a foot of snow may fall in a swath from the Plains into the Upper Midwest. Image provided by Pivotal Weather.
More than a foot of snow may fall in a swath from the Plains into the Upper Midwest. Image provided by Pivotal Weather.

As the system heads eastward, snow will move into portions of the Mississippi Valley and the Upper Midwest on Friday. The heaviest snow looks to stay just south of the Twin Cities, but even there, moderate to heavy snow is likely. By the time the storm moves out on Saturday, a foot or more of snow is possible in a swath from the Central Plains into the Great Lakes.

Snow isn’t the only threat from this system. As the storm moves eastward, record warmth will remain in place across the Midwest. With warm, moist air in place and a strong cold front approaching from the West, strong to severe thunderstorms are possible across portions of the Lower Great Lakes and Ohio Valley on Friday. Some of the stronger storms that form may contain damaging winds, hail, and possibly tornadoes.

The Storm Prediction Center has already highlighted the Midwest as an area to watch for severe weather on Friday. Image provided by NOAA.
The Storm Prediction Center has already highlighted the Midwest as an area to watch for severe weather on Friday. Image provided by NOAA.

The system will continue to move eastward, bringing some rain to the East Coast on Saturday, but amounts should be fairly light, and additional severe weather is not anticipated.

Heavy Rain and Snow Heading for California, Snowstorm Likely for the Southeast, New England

A developing storm system will bring heavy snow to parts of the Southeast and New England this weekend, while the West Coast braces for a lot of much-needed rainfall.

GFS Model forecast for rainfall through next Friday evening. Image provided by WeatherBell.
GFS Model forecast for rainfall through next Friday evening. Image provided by WeatherBell.

 

We’ll start on the West Coast, where a series of storm systems will bring plenty of rain to drought-stricken California. While this will not alleviate the drought that has been ongoing for years, it will help to put a big dent into it. The first of the storm systems will move in tonight, and by the time the last one moves through next Friday, rainfall totals of 5-10 inches will be widespread across much of central and Northern California, with many locations, especially along the coast and western slopes of mountains receiving 10-20 inches or more.

GFS Model forecast for snowfall through next Friday evening. Image provided by WeatherBell.
GFS Model forecast for snowfall through next Friday evening. Image provided by WeatherBell.

 

At the higher elevations, especially in the Sierra Nevada, incredible amounts of snow are expected. The snowpack, which much of the region depends on for water in the summer as it melts, is already above normal, and over the next week, some locations might see 6-12 FEET of new snow from these storm systems.

A variety of precipitation is falling across the Southeast this evening. Loop provided by Weathertap
A variety of precipitation is falling across the Southeast this evening. Loop provided by Weathertap

 

Back in the East, a storm system is riding along a stalled out front across the Southeast, producing some snow across parts of the Tennessee Valley and the Southeast. As this system draws in moisture from the Gulf of Mexico and the Atlantic, and runs into an arctic airmass already settling into the region, it will produce heavy snow in places that normally don’t see a lot of snow, such as Georgia, the Carolinas, and the Virginia Tidewater area. In these places, even a dusting of snow can cause traffic nightmares, so heavy snow can bring these areas to a standstill.

GFS model forecast for snow across parts of the Southeast and Mid-Atlantic states through Sunday morning. Image provided by Pivotal Weather.
GFS model forecast for snow across parts of the Southeast and Mid-Atlantic states through Sunday morning. Image provided by Pivotal Weather.

 

The heaviest snow from this system is expected across the Appalachians and also across the Virginia Tidewater area, as the storm gathers strength while moving into the Atlantic. Of course, the 6-12 inches expected across much of North Carolina will cause its own problems, but luckily, the bulk of the snow will fall tonight and Saturday, minimizing the travel problems. The heaviest snow should remain just south and east of the big cities of Washington, Philadelphia, and New York, but a few inches may fall in each location.

Once this storm moves off the Mid-Atlantic coast it will head northeastward, passing a couple of hundred miles south and east of Cape Cod. Normally, this would mean just a little bit of light snow for parts of Southern New England, and for the most part, that’s what we’re expecting. However, for southeastern New England, mainly south and east of I-95, it’ll be a different story from Saturday afternoon into Sunday morning.

There are a couple of factors that will enhance snowfall totals across this region. First, with northeasterly winds blowing off the Atlantic, we’ll get some ocean-effect snowfall. This is similar to the lake-effect snow that you often see near the Great Lakes. Second, temperatures will only be in the upper teens to middle 20s. This means that it will be more of a fluffy snow, which will pile up quicker than a much wetter snow.

NAM Model forecast for snowfall through Sunday evening. Image provided by Earl Barker’s Weather Models.
NAM Model forecast for snowfall through Sunday morning. Image provided by Earl Barker’s Weather Models.

 

The snow should start to develop across Cape Cod and southeastern Massachusetts Saturday morning, and will quickly spread inland. The snow should spread as far inland as central Massachusetts and southern New Hampshire, but it will quickly retreat eastward again, ending in most places during the evening. The exception is Cape Cod and coastal Massachusetts, where northerly winds behind the storm may keep the ocean-effect snow going into the early hours of Sunday morning.

For snowfall totals, we’re not expecting more than an inch or two from southern New Hampshire into Central Massachusetts. Points north and west of Boston and Providence, including the Merrimack Valley, will likely see 2-4 inches, with some heavier amounts across Cape Ann. Along and south of Interstate 95, including the southern and eastern suburbs of Providence and Boston, totals of 6-12 inches seem likely, with the best chance for more than a foot of snow across parts of Plymouth County and Cape Cod, where the ocean enhancement will play a big role.

Behind the system, with fresh snow cover, temperatures will turn colder. Monday morning, temperatures will be in the single numbers across much of the region, with some sub-zero readings likely. The next storm moves in later on Tuesday, and although it will start as some snow or a wintry mix, milder air will move in, with the bulk of the precipitation falling in the form of rain Tuesday night into Wednesday.

Big Changes Coming to the Nation’s Heartland

Even though we’re into the middle of November, it hasn’t felt like late autumn across much of the nation. That’s about to change, especially across the Plains states and the Midwest.

Temperatures have been as much as 10-15 degrees above normal this month across the Northern Plains. Image provided by WeatherBell.
Temperatures have been as much as 10-15 degrees above normal this month across the Northern Plains. Image provided by WeatherBell.

 

A storm system will move out of the Rockies and across the Plains states over the next few days. Ahead of the system, warm, moist air will be drawn northward from the Gulf of Mexico. High temperatures on Thursday will be in the 70s as far north as Iowa and Illinois, with record high temperatures expected across much of the Mississippi Valley. The warmth won’t last too much longer though, as a strong cold front will be marching eastward across the Great Plains.

Numerous record high temperatures are expected on Thursday across the Mississippi Valley. Image provided by WeatherBell.
Numerous record high temperatures are expected on Thursday across the Mississippi Valley. Image provided by WeatherBell.

 

Behind the front, much cooler air will settle southward from Canada. With plenty of moisture being drawn northward, it will fall as snow on the backside of the low from the Central Rockies and Central Plains northeastward into the Upper Midwest. Some of the snow could be heavy, especially in parts of South Dakota and Minnesota, where snowfall totals of 10-15 inches are possible by Saturday evening. Winter Storm Watches have been posted from eastern Wyoming and northern Nebraska northeastward to Minnesota.

Snowfall forecast through Saturday evening from the GFS model. Image provided by Pivotal Weather.
Snowfall forecast through Saturday evening from the GFS model. Image provided by Pivotal Weather.

 

Snow isn’t the only hazard with this system. As it strengthens, it will create strong winds across much of the Plains states. Sustained winds of 20-30 mph with gusts to 50 mph or more are expected, especially from the Dakotas into Nebraska. The combination of high winds and snow may result in blizzard conditions at times. A blizzard watch has been issued for southwestern Minnesota, northeastern South Dakota, and extreme southeastern North Dakota.

Current watches and warnings across parts of the Plains States. Image provided by NOAA.
Current watches and warnings across parts of the Plains States. Image provided by NOAA.

 

Once the system moves into southern Canada this weekend, some of the coldest air so far this season will settle into the region. While these temperatures aren’t that unusual for late November, they will be quite a change from the recent warmth that has enveloped the area. Low temperatures will likely drop into the teens and 20s across the region this weekend, with single digits possible. In some of the locations with fresh snowcover some sub-zero readings are possible. The cool air will be short-lived, as temperatures will likely warm back up to above normal readings by early next week. Current indications are that the unseasonably mild weather will persist for the most part well into December across the region.

October in the Northeast Means a Little Bit of Everything

October can be a time of change in the Northeast. While the first thing that comes to mind is the changing colors of the foliage across the region, the weather also changes, sometimes quite frequently. That’s what we’re going to be dealing with for the next few days.

Unseasonably warm weather was observed across much of the Northeast for the past few days, with high temperatures soaring well into the 70s and 80s across much of the region. This resulted in dozens of record high temperatures. However, some changes are coming, and the warm weather will be a distant memory within the next 24-48 hours.

Record high temperatures broken across the Northeast on Monday October 17 and Tuesday October 18. Image provided by NOAA.
Record high temperatures broken across the Northeast on Monday October 17 and Tuesday October 18. Image provided by NOAA.
Record high temperatures broken across the Northeast on Wednesday October 19. Image provided by NOAA.
Record high temperatures broken across the Northeast on Wednesday October 19. Image provided by NOAA.

 

A cold front moved across the region on Wednesday with little fanfare. That front will stall out to the south of New England overnight. On Thursday, a wave of low pressure will start to approach from the west. This will spread rain and showers into the area. Some of the rain will be heavy, especially from New York into Pennsylvania late Thursday into Friday. With rainfall totals of 1-3 inches and locally up to 5 inches expected, some flooding is likely. Across New England, where a serious drought is ongoing, rainfall will be much lighter, with most locations likely receiving under half an inch of rain.

Expected rainfall through Friday evening across the Northeast. Image provided by Pivotal Weather.
Expected rainfall through Friday evening across the Northeast. Image provided by Pivotal Weather.

 

As that wave of low pressure moves into Upstate New York on Friday, it will lift that cold front northward across the region as a warm front once again. While Friday won’t be as warm as the past few days, high temperatures will still get into the 60s and lower 70s. With dewpoints also in the 60s, it will be a rather muggy day for mid-October.

Computer model forecasts for the track of a tropical disturbance in the Bahamas. Image provided by Tropical Tidbits.
Computer model forecasts for the track of a tropical disturbance in the Bahamas. Image provided by Tropical Tidbits.

 

Meanwhile, there is a tropical disturbance brewing near the Bahamas. Upper-level conditions are somewhat favorable for development, and the system could become a tropical depression or subtropical storm on Thursday. The system will likely head northward, moving towards the Gulf of Maine and merging with the cold front approaching from the west as we head into the weekend. This will bring another round of heavy rainfall into Maine and Atlantic Canada, areas that were hit hard by heavy rain from Hurricane Nicole just a week ago.

Expected rainfall between Friday evening and Sunday evening across the Northeast. Image provided by Pivotal Weather.
Expected rainfall between Friday evening and Sunday evening across the Northeast. Image provided by Pivotal Weather.

 

Once the system moves into southeastern Canada, it is expected to stall out under an upper-level low pressure area and become a strong extratropical system. It will drag a cold front across the Northeast, bringing much colder air into the region. With strong low pressure nearby and much colder air filtering in, rain will change over to snow across portions of Upstate New York and Northern New England. While the snow will be confined mainly to the higher elevations, this is the first accumulating snow of the season across the area. Several inches may accumulate across parts of the Adirondacks and the Green Mountains.

Expected snowfall through Monday evening across the Northeast. Image provided by WeatherBell.
Expected snowfall through Monday evening across the Northeast. Image provided by WeatherBell.

 

While there could be a few wet flakes mixed in with some of the rain across lower elevations of Central New England, accumulating snow is not expected.Sunday will be a chilly day, with highs only in the 40s and 50s across much of the Northeast. These readings are 10-20 degrees below normal. Of course, any mention of snow in October across the Northeast will make residents think back just a few years to the pre-Halloween snowstorm that dropped 1-2 feet of snow across parts of the region, setting numerous records. While this system won’t come anywhere close to that, it should make for some spectacular photos of snow-capped mountains and valleys filled with colorful foliage early next week.

nowfall from the Halloween snowstorm of 2011. Image provided by NOAA.
Snowfall from the Halloween snowstorm of 2011. Image provided by NOAA.

 

The other thing the storm will do and bring gusty winds to much of the Northeast through the weekend. Northwest winds of 15-25 mph may gust to 40 mph at times, especially across New England. This may result in some spotty wind damage across parts of the area. The other effect it will have is to create rather chilly conditions. Just a few days as experiencing temperatures in the 60s, 70s, and 80s, highs will only be in the 40s and 50s across much of the area, with wind chills in the 30s and 40s. This is the type of change that October is known for across the Northeast.

The Rainy Season Is About to Start in the West

Across much of the West, the bulk of the rainfall that falls during the year usually falls between October and April. This year is starting off right on schedule as a storm system is poised to bring heavy rain to parts of the region over the next few days.

Surface analysis across the Pacific Ocean from Monday afternoon October 10. Image provided by NOAA.
Surface analysis across the Pacific Ocean from Monday afternoon October 10. Image provided by NOAA.

 

A strong low-pressure system passing south of the Aleutians on Monday will move into the Gulf of Alaska over the next 24-48 hours, before heading towards British Columbia and the Pacific Northwest. The storm will bring heavy rainfall and strong winds to the Aleutians and portions of southern Alaska through midweek. Along the coast, wind gusts may reach hurricane force. With the slow movement of the storm, and the strong onshore winds, heavy rain is likely across much of the Aleutians, with totals in excess of five inches possible.

Expected rainfall across the Pacific Northwest through Friday evening. Image provided by WeatherBell.
Expected rainfall across the Pacific Northwest through Friday evening. Image provided by WeatherBell.

 

By midweek, as the storm moves towards the coast of British Columbia and Washington, rain will move into the Northwest.  The heaviest rain is expected during Thursday and Friday, with several inches likely west of the Cascades, especially along the west slopes of the coastal mountains. This will likely lead to flooding in some areas. In addition to the rain, strong winds will blast the coastline. Wind gusts of 60-80 mph are possible, especially along the coast of Oregon.

GFS model forecast for peak wind gusts along the coast of Oregon Thursday afternoon. Image provided by WeatherBell.
GFS model forecast for peak wind gusts along the coast of Oregon Thursday afternoon. Image provided by WeatherBell.

 

As the system pushes inland, rain will spread southward into northern California by late Thursday, likely reaching as far south as central California. This will bring beneficial rain into portions of the region, including the Bay Area, where several wildfires continue to burn. After a dry summer, this rain will be very helpful to firefighting efforts across the area. Rainfall totals of 1-3 inches are possible, with heavier amounts along the northwestern coast of the Golden State.

Active wildfires across California as of Monday afternoon October 10. Image provided by California Department of Forestry and Fire Protection.
Active wildfires across California as of Monday afternoon October 10. Image provided by California Department of Forestry and Fire Protection.

 

As the rainfall moves inland, it will change to snow across the higher elevations of the Sierra Nevada. Snow levels will remain fairly high with this system, likely around 7000 feet. Above that, especially above 9000 feet, snowfall totals of 8 to 16 inches are possible. While this is not the first snow of the season in the Sierras, it is the first significant storm of the season.

Once this system pushes inland, another strong storm looks to follow on its heels. Another round of strong winds and heavy rain is expected to move into the Northwest and Northern California for the weekend. That storm may be the remnants of Typhoon Songda, currently passing out to sea and weakening south and east of Japan.

The Feel of Fall is Arriving

Astronomical fall begins on September 22 at 10:21am EDT, but meteorological fall is defined as the period between September 1 through November 30. While it can and does still feel like summer across parts of the nation, there are more and more signs that summer is winding down.

As the nights start to grow a little longer the farther north you go, the cooler air starts to build up a little more, especially as you head into Canada and Alaska. The cold fronts that drop down from Canada and into the Northern US start to pack a little more punch. One of those fronts is moving across portions of the Upper Midwest and the Great Plains today. The airmass moving into the Rockies and Northern Plains behind the front is sending temperatures as much as 15 to 25 degrees below normal this afternoon.

Temperatures will be 15 to 25 degrees below normal across the Northern Rockies and Northern Plains today behind a cold front. Image provided by Pivotal Weather.
Temperatures will be 15 to 25 degrees below normal across the Northern Rockies and Northern Plains today behind a cold front. Image provided by Pivotal Weather.

As that airmass settles in, low temperatures will drop into the 30s and 40s across the Northern Plains and Rockies tonight. Frost advisories and freeze warnings have been posted for western portions of North Dakota for Tuesday morning. By Wednesday morning, the coldest air will move over Minnesota, where low temperatures could drop into the upper 20s and 30s. Additional frost and freeze advisories will likely be issued for this region.

GFS model forecast for low temperatures across Minnesota Wednesday morning. Image provided by WeatherBell.
GFS model forecast for low temperatures across Minnesota Wednesday morning. Image provided by WeatherBell.

Cold temperatures aren’t the only noteworthy item with this cold front. As the cold air surges into the Rockies, precipitation will accompany it. That precipitation will likely fall as snow in many areas, mainly at elevations above 5000 feet. Across some of the higher peaks, more than a foot of snow could accumulate over the next day or two. Winter Weather Advisories have been issued for portions of northern Wyoming as a result.

GFS model forecast for snowfall through Wednesday morning. Image provided by WeatherBell.
GFS model forecast for snowfall through Wednesday morning. Image provided by WeatherBell.

Some snow is also possible across the higher elevations of the Sierra Nevada as the cooler air spreads into the West. While accumulations will be minor, this will likely be the first snowfall of the year for this region. Across the rest of the Golden State, temperatures will likely be 6 to 12 degrees below normal on Tuesday, with highs only in the 70s to lower 80s, a welcome change from the 90s and 100s they’ve had for most of the summer.

While this front will bring cooler air into the Northeast later this week, one thing it won’t do unfortunately, is bring beneficial rainfall to the region. It will produce showers and some thunderstorms, and while a few of the storms may contain heavy downpours, they’ll be very localized. Across much of the region, rainfall totals will be generally under half an inch. This will do little to put a dent in the severe drought that much of the region is currently experiencing. Rainfall deficits of 5 to 10 inches below normal since the beginning of March are common across the region.

Rainfall deficits across the Northeast from March 1 through August 31. Image provided by the Northeast Regional Climate Center.
Rainfall deficits across the Northeast from March 1 through August 31. Image provided by the Northeast Regional Climate Center.

 

While this early taste of fall moving into much of the Northern US this week is not uncommon for mid-September, it might not be repeated much this fall. Long-range forecasts are showing the likelihood of a warmer than normal fall across much of the United States.

 

 

 

 

Change is in the Air

As we head into the end of August, some familiar things start to happen. Children will start to head back to school. Baseball’s pennant races heat up while football at all levels gets ready for the start of the season. Halloween candy starts to appear in stores and it will be followed shortly by pumpkin-flavored everything. In terms of the weather, familiar things happen there too. The tropics start getting more active and the cold fronts dropping southward from Canada pack a little more punch than they usually do during the summer.

One of those cold fronts will be moving across the Plains states and into the Midwest over the next few days. Ahead of the front, summertime heat and humidity remains in place, with temperatures well into the 80s and 90s common. Behind the front is much cooler and drier air. By Friday morning, temperatures will be 10-20 degrees below normal across much of the Plains states and Rocky Mountains as a large area of high pressure builds in from Canada. Low temperatures will drop into the 40s and 50s across the Northern Plains, with 30s and even some upper 20s from the Rocky Mountains into interior portions of the Pacific Northwest.

Temperature anomaly map based on the GFS model for Thursday morning. Image provided by Pivotal Weather,
Temperature anomaly map based on the GFS model for Thursday morning. Image provided by Pivotal Weather.

As that cooler air settles into the region, some snow is possible across the higher elevations of the Northern and Central Rockies. Snow levels will remain fairly high, but a few inches of snow may accumulate on top of some of the higher peaks in Wyoming and Colorado.

Snowfall forecast based on the GFS model through Friday morning. Image provided by WeatherBell.
Snowfall forecast based on the GFS model through Friday morning. Image provided by WeatherBell.

Ahead of the front, a warm and humid airmass will remain in place, with high temperatures well into the 80s and 90s for the next few days. As the front approaches, it will trigger showers and thunderstorms. Some of the storms could be strong to severe, with hail and gusty winds possible, along with a few tornadoes. The biggest threat looks to be heavy rain and flash flooding. Because the front will be moving fairly slowly, some of the heavier storms will linger over the same areas. Rainfall totals of 1-3 inches will be common across parts of the Eastern Plains and Mississippi Valley, with some heavier amounts possible. This will likely lead to flooding in some areas.

Expected rainfall totals across the Midwest through Friday morning. Image provided by WeatherBell.
Expected rainfall totals across the Midwest through Friday morning. Image provided by WeatherBell.

Meanwhile, in the Atlantic, we’re keeping an eye on a disturbance east of the Lesser Antilles and Tropical Storm Gaston out in the Central Atlantic. There was a third system, Tropical Depression Fiona, but it fizzled southeast of Bermuda earlier today.

Satellite loop showing Tropical Storm Gaston (far right) and a disturbance approaching the Eastern Caribbean. Loop provided by NOAA.
Satellite photo showing Tropical Storm Gaston (far right) and a disturbance approaching the Eastern Caribbean. (Click for loop) Provided by NOAA.

Tropical Storm Gaston is centered about 700 miles west of the Cape Verde Islands this afternoon, heading towards the west-northwest at 21 mph. Maximum sustained winds are near 65 mph, and additional strengthening is expected. Gaston should become a hurricane by Wednesday afternoon. The forecast for Gaston is to turn more towards the northwest, heading out in the Central Atlantic Ocean before starting to weaken in a few days. Gaston will likely bot be a threat to any land areas.

Meanwhile, a disturbance located a few hundred miles east of the Lesser Antilles is being carefully monitored for signs of development. United States Air Force Reserve Hurricane Hunter aircraft investigated the system earlier today and found it to be a weak system with an ill-defined center. Conditions are still somewhat favorable for further development, and anyone with interests in the northeastern Caribbean should continue to monitor the progress of this system. The future of this system is still a big question mark. Most of the forecast models bring the system towards the Bahamas over the next several days, though a few have the system dissipate completely before then. Once it gets to the Bahamas, there is considerable spread among the models as to where it will go, assuming it even survives that long. Some have it turn northward and head towards the Carolinas or Georgia. Some bring it into Florida, then up into the Southeast, and others bring it across Florida and into the Gulf of Mexico. As for how strong it could be, that’s an even bigger question mark. As mentioned previously, some of the models have it dissipate completely. There are other models that keep the system as a tropical depression or weak tropical storm into the Bahamas. There are others that have it as strong as a Category 2 hurricane. Once the storm actually forms (assuming it actually does), the computer models should start to get a better handle on its future.

Computer model forecasts for the track of a disturbance approaching the Eastern Caribbean. Image provided by Tropical Tidbits.
Computer model forecasts for the track of a disturbance approaching the Eastern Caribbean. Image provided by Tropical Tidbits.
Computer model forecasts for the intensity of a disturbance approaching the Eastern Caribbean. Image provided by Tropical Tidbits.
Computer model forecasts for the intensity of a disturbance approaching the Eastern Caribbean. Image provided by Tropical Tidbits.

A Look at Winter’s Pattern

Meteorological winter spans December 1st to the end of February, which falls on February 29th this year. The last few days of February likely won’t have a large effect on the overall winter pattern so leaving them off won’t drastically affect the overall results. So let’s jump in.

The area where El Nino is tabulated from.
The area where El Nino is tabulated from.
Above normal sea surface temperatures in the Pacific Ocean around the equator indicating the El Nino.
Above normal sea surface temperatures in the Pacific Ocean around the equator indicating the El Nino.
The NAO, AO, PNA for the winter season where all mainly above normal, aside from a brief negative of the NAO and AO in January.
The NAO, AO, PNA for the winter season were all mainly above normal, aside from a brief negative of the NAO and AO in January.

 

The major headlining variable controlling a large part of winter is the Strong El Nino in the Pacific Ocean. This El Nino was one of the warmest on record in terms of the normal place where readings are taken in the middle of the ocean. This is very important because El Nino has a huge effect on winter’s sensible weather and there are obvious signs that it was occurring during winter. The easiest sign that El Nino is occurring is that the subtropical jet stream which usually sets up near or just south of the Southern United States. This did occur this year and likely allowed for stronger low pressure systems during this year’s winter. This winter’s precipitation departure from normal plot shows the East Coast with above normal precipitation. Also, the warmer than normal sea surface temperatures along the East Coast likely contributed to the strength of the low pressure system in that area.

Winter temperature anomalies. Notice the lack of below normal temperatures in the United States.
Winter temperature anomalies. Notice the lack of below normal temperatures in the United States.
Winter precipitation anomalies. Notice the above normal anomalies in the East Coast and the Pacific Northwest.
Winter precipitation anomalies. Notice the above normal anomalies in the East Coast and the Pacific Northwest.
Winter averaged jet stream place. Notice the subtropical jet from the Gulf of Mexico to the Norheast.
Winter averaged jet stream place. Notice the subtropical jet from the Gulf of Mexico to the Norheast.
Mid Level geopotential heights. Generally, the below normal heights indicate low pressure and above normal heights indicate high pressure.
Mid Level geopotential heights. Generally, the below normal heights indicate low pressure and above normal heights indicate high pressure.

In order for there to be plenty of wintry precipitation, we need lots of precipitation, which we know we had, but we also need plenty of cold air. Last winter, it seemed we could never get out of the cold air. Cold air was locked in Canada and whenever the jet stream came in from Canada, it seemed another snow storm was forming during January and February. This year, warmer air than normal was locked in Canada. So, while we had winds in from Canada, cold air was harder to tap into for winter storms. The only storm with all snow this winter was the blizzard that buried the Washington DC area, which occurred on January 22nd to 24th. The Northeast Storm Impact Scale (NESIS) compiled by renowned snow storm researchers Paul Kocin and Louis Uccellini identified this storm as a category 4, or “crippling”, winter storm and is rated as the 4th most powerful snow storm since 1950. Most of the other storms that impacted the East Coast were snow mixed with rain and ice precipitation types. One reason this may be is because we had warm phases of the North American Oscillation (NAO) and Arctic Oscillation (AO) as a winter average meaning there was no blocking in the jet stream flow to allow for storm development and the teleconnection phases likely contributed to the lack of cold air. Furthermore, the 15 day period where the NAO and AO went to the cold phase and then trended back towards the warm phase that allowed for the January Blizzard, so that likely had an effect on the winter pattern. Even still, the Northeast ended up with a winter of around normal snowfall accumulation.

Finally, El Nino’s are also known for having plenty of moisture flowing into California, but this El Nino had the moisture flowing into the Pacific Northwest instead as a result of the average placement of the low pressure system and jet stream off the Eastern Pacific Ocean. The general low pressure system‘s placement was in the Gulf of Alaska and concurrently, the general place of the jet stream was north of San Francisco. When this placement occurs, areas north of the jet stream get precipitation, but those south of the jet stream receive minimal precipitation. This along with an average of above normal heights, which indicates drier air, in the Southwestern US brought the moisture into the Pacific Northwest instead of Southern California.

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