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.
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.
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 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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 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.
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.
The Northeast is in the news once again, but it isn’t about snow this time. It’s about the cold air, which has entered the Northeast, but will reach its coldest Saturday night. The highest difference in temperatures is forecast to be in Islip, New York, on Long Island, where the temperatures is forecast to drop to around 1 degree. The record low temperature for that day is 7 so a difference of 6 degrees is forecast. Two of the lowest temperatures are forecast to be around -12 degrees in Albany, New York and Worcester, Massachusetts. Worcester has actually gotten down to -11 before as a low temperature on February 14th before while Albany has reached -10 on this date before so it certainly is in their climatology to reach very cold temperatures this time of year. As such, numerous wind chill advisories have been issued across the Northeast through Sunday midday as record cold temperatures pair with windy conditions. Wind gusts may approach 30 miles per hour at times, especially during the day.
So what is the cause of this record cold? In order to understand this, a general climatology of temperature within the bottom two layers of the atmosphere must be given as a framework. At the bottom of the atmosphere, the earth’s surface is warm because the earth’s surface absorbs the sun’s energy the best. Then there’s a decline in temperature from the lowest point in the lowest layer on the earth, called the troposphere, to the highest point within the troposphere, called the tropopause. The temperature slightly rises from the bottom of the stratosphere to the top of the stratosphere as a result of ozone absorbing the sun’s energy. Then a slight lowering in the temperature occurs in the mesosphere and a slight rise in the temperature occurs in the thermosphere.
This is important because this shows that what happens in the troposphere (the lowest atmospheric layer) has huge implications on what the weather does. It also shows that the stratosphere also has an impact on the earth’s weather, for example, the height of tropopause (the top of the troposphere) can indicate how cold the surface will be. We already know that record temperatures are swinging through Saturday and early Sunday morning. This is also the time that the tropopause drops to its lowest height. Another indication of the cold temperatures would be to have temperatures in the upper levels that are above normal because that would mean below normal temperatures in the lower levels based on our atmospheric structure. Temperatures in the layer that the jet stream normally occurs are 2 to 3 degrees above normal. Admittedly, this temperature is certainly not as cold as it could be and could be warmer according to the NAEFS model situational awareness table, which has these jet stream level temperatures being about average.
This air mass should leave the Northeast especially by Monday as another low pressuresystem approaches bringing warmth from the south and the precipitation type changes from snow to rain or freezing rain overnight.
A strong storm will be moving from Canada into the Great Lakes Sunday and Monday with some light snowfall. This storm is currently being highlighted by blizzard watches and warnings as well as high wind watches and warnings. Many associate a storm that has the blizzard tag with high snowfall amounts, but because the ground is so dry and the air so cold up in the Midwest, blizzards are actually easy to come by.
The National Weather Service defines a blizzard at a particular observation station that has two main conditions occur during a period of 3 hours. The stations must have sustained or frequent gusts at or above 35 miles per hour and considerable falling or blowing so that visibility is reduced to less than one quarter of a mile. Notice how there is no requirement of reaching an exact snowfall measurement. For what it’s worth current forecasts have between 1 and 3 inches for the area with higher totals near 6 inches in the higher elevations.
One of the main features of this storm will be how anomalously strong it is. The way storm strength is measured outside of strength of winds like hurricane strength is to measure the lowest pressure in the center of the storm. For this particular event, it reaches a pressure of 995 mb according to the American Global Ensemble Forecast System (GEFS) model. The 995 mb compared to the climatological sea level pressure on that date of around 1020 mb, a departure from normal of 25mb. However, low pressure systems of that strength are quite common and the climatology is also offset by high pressure systems going through the same area. Wind strength can also be ascertained by the number of contours between the high pressure center’s highest pressure and the low pressure’s lowest pressure. In this case, the GEFS shows the difference between the between the two pressures is 43 mb with the high pressure reaching a pressure of 1038 mb. That indicates some strong winds through the area so that any snow could get lifted in the strong winds.
Winds are strongest aloft because the winds run into the surface of the earth and friction slows them down at the surface. So winds must be brought from aloft down to the surface. The way to do this is to use momentum transfer through up and down motions in the atmosphere, which are called eddies. These eddies are worth considering when lapse rates or the difference between the surface a particular point in the atmosphere (generally surface lapse rates are quantified as the layer between where the pressure is 850 mb, or about 1.5 kilometers into the sky, and the surface) are near or greater than 10 C per kilometer. This occurs during the time of peak heating during the day on Sunday with sustained winds having the possibility of being near 50 knots or about 58 miles per hour and gusts could being near 60 knots or close to 70 miles per hour during the time of strongest lapse rates according both the American NAM and GFS models. This well over blizzard criteria and while the 3 hour period will certainly need to be watched, it doesn’t seem too hard for it to occur based on the forecast models.