Category: Severe Weather

Showers and a few isolated thunderstorms started the morning in portions of the Northern Plains. As the day goes on, those showers and storms will move toward the east as a low pressure system and its warm front move northeast. One question will be if the cloud cover can subside and allow for enough surface heating. If the clouds do break, this will allow for stronger afternoon showers and thunderstorms to pop over eastern portions of North Dakota and South Dakota. Otherwise, the start of those pop-up showers and thunderstorms may be delayed and may actually occur in Minnesota. Any pop-up storms will be moving to the north or northeast through the evening hours and into Minnesota, Canada and possibly Northern Wisconsin overnight. With all this in mind, it’s entirely possible that most unstable CAPE values top out over 1000 J/kg and shear values reach over 30 to 40 knots and so the main threats for these storms will be strong winds, hail, heavy rain and a tornado or two. Behind the low pressure system for Sunday, cold air will be pouring in on strong winds from the north, cutting down the humidity.

Meanwhile, the tropics continue to be active, especially in the Pacific Ocean with Hurricane Jimena continuing to move on a northwest track. Jimena is forecast to slowly weaken to a tropical storm tonight. By midweek, a trough is expected to dive south from the north-central Pacific. Because of this, some models, as well as the National Hurricane Center (NHC), indicate the storm may take a track toward the Hawaiian islands of Kauai and Oahu. This is not entirely set in stone with a few models also taking the storm straight west, to the north of Kauai. Also, the Western Pacific has a strong typhoon (Kilo) which has been a typhoon since it crossed the dateline as a hurricane and may continue churning in the Pacific for a while longer. A strong disturbance in the Eastern Pacific located a few hundred miles west of the southern tip of the Baja California Peninsula may develop into a tropical system later today or Sunday. Post-tropical storm Kevin continues to weaken as it takes a track to the northwest, just west of the Baja California Peninsula. El Nino has had a strong effect on this year’s tropical activity with the strong positively anomalous warm sea surface temperatures supporting and enhancing the Pacific hurricanes and typhoons.

In the Atlantic, Tropical Depression Fred continues to spin over the open ocean and will move toward the west-northwest. It is forecast to track toward the north and then to the northeast during the next two days. Tropical Depression Fred has been running into strong shear, which should continue to slowly downgrade Fred, as indicated by NHC. In addition, a new tropical storm (Grace) has formed in the Atlantic and is located 285 Miles southwest of the Cape Verde Islands. Grace will take a trek toward the west maintaining tropical storm strength the whole time. However, it may run into shear over the next 2 to 3 days, which could cause the storm to weaken or dissipate east of the Lesser Antilles. Previous storms Danny and Erica ran into problems with shear and dissipated because of it already this year.  Shear has been a problem this year for storms in the Atlantic even as warm water has helped to awaken the Atlantic. Even though, El Nino helps to create favorable conditions in the Pacific Ocean, it helps to create unfavorable conditions in the Atlantic Ocean in the form of shear ripping apart any tropical systems that aren’t big or strong enough to maintain themselves with in it.

A strong cold front will move across the Northeast on Tuesday, producing showers and thunderstorms across the region, and bringing much drier air into the region.

Showers and a few thunderstorms are expected across the region in the morning. If enough clearing develops after these move out, the atmosphere could destabilize enough to trigger another round of showers and thunderstorms in the afternoon, and some of these could become strong to severe. The Storm Prediction Center is forecasting a marginal risk of severe storms across much of central and southern New England for Tuesday. The main threats with any storms that develop will be heavy rainfall, strong winds, and frequent lightning.

Behind the front, much drier air will settle in, after more than a week with dewpoints of 70 degrees or higher. Temperatures will remain seasonably warm though, unlike areas to the west, where much cooler conditions were noted behind the front. In Rapid City, South Dakota, the low temperature dropped to 41 degrees Monday morning, breaking the old record of 43 degrees, set in 1972. Cheyenne, Wyoming dropped to 39 degrees Monday morning, which also broke a record. The old record low was 40, set 119 years ago in 1896. Several locations in Montana dropped below freezing Sunday morning, with frost reported across parts of the area.

Meanwhile, the tropics remain active. Tropical Storm Erika has formed about 955 miles east of the Leeward Islands. Erika has maximum sustained winds near 45 mph, and is moving toward the west at 20 mph. Erika is expected to slowly strengthen over the next 24-48 hours while turning a bit more towards the west-northwest. The current forecast brings Erika very close to the Northern Leeward Islands Wednesday night or early Thursday. Watches will likely be issued for some of the islands early Tuesday. Beyond that, there is plenty of uncertainty as to where Erika will head and how strong it will be. Some of the models have Erika dissipate over the eastern Caribbean, similar to what happened to Danny, over the next few days, others strengthen it into a hurricane and send it towards the Bahamas.

Since Danny fizzled while it was crossing the Leeward Islands, it brought only a few showers to the Virgin Islands. This region has been in a severe drought for the past several months, and it was hoped that Danny would bring some much -needed rain to the region to help put a dent in the drought. St. Croix, USVI has received only 7.31 inches of rain in 2015, a little over 12 inches below the normal total of 12.33 inches. Things haven’t been much better in San Juan, Puerto Rico, where 21.8 inches of rain have fallen this year,  10.38 inches below the normal for the year-to-date.

Meanwhile, in the Eastern Pacific, Tropical Depression 12-E formed late Monday. The depression was centered about 1535 miles west-southwest of the southern tip of Baja California with top winds near 35 mph. The depression was drifting toward the west at 3 mph, but should start to turn more towards the west-northwest and pick up speed over the next few days. The system should strengthen into a tropical storm over the next day or so and head out over the open waters of the Pacific, not threatening any land areas. Another tropical wave south of Mexico could develop into a tropical depression later this week as it moves across open waters.

In the Central Pacific, Tropical Depression Kilo has top winds near 30 mph and is centered about 150 miles east of Johnston Island. It is expected to drift toward the north then turn toward the west over the next few days with some slow strengthening expected. Kilo is not expected to impact any land areas for the next few days. Meanwhile, Hurricane Loke is located over 1000 miles west-northwest of the main Hawaiian Islands, crossing the Pearl and Hermes Atoll with top winds near 75 mph. Loke is expected to turn towards the north-northwest and head out over the open waters of the North Pacific while losing tropical characteristics over the next few days.

In the Western Pacific, Typhoon Goni has crossed southwestern Japan and is moving into the Sea of Japan Tuesday afternoon. Goni still has top winds near 95 mph, but is expected to steadily weaken as it crosses the Sea of Japan and heads toward far eastern Russia. Goni produced a wind gust to 102 mph in Makuazaki when it made landfall on Monday. On Sunday, Goni crossed the Ryukyu islands, southwest of the Japanese mainland. As the storm passed directly over Ishigakijima, it produced a wind gust to 159 mph.

Tropical Storm Danny is the main weather story for today. However, after registering a category 3 rating for winds in a previous hurricane hunter recon mission, it is only a tropical storm and continues to decrease in strength. This is evidenced by the storm’s central pressure rising to just above 1000 mb this afternoon, significantly higher than 2 days ago. While the forecast track is still a little uncertain, the current forecast from the National Hurricane Center (NHC) is for the storm to take a track to the west, just south of Puerto Rico overnight Monday. This is just after a recent track change from toward the northwest to toward the west. The storm will continue to weaken and should be a tropical depression after crossing the Leeward Islands according to NHC’s forecast. Currently the NHC has posted Tropical Storm Warnings for Antigua, Barbuda, Montserrat, St. Kitts, Nevis and Anguilla and Tropical Storm Watches for Saba and St. Eustatius, St. Maarten, Puerto Rico, Vieques, Culebra, and the US Virgin Islands.

The storm itself is about 165 miles east-southeast of Guadeloupe and 210 miles east-southeast of Antigua. The maximum sustained winds within the storm are 40 MPH and will continue moving west at 16 MPH. Threats for this storm will be for rain from 2 to 4 inches of rain through Tuesday and wind up to tropical storm force in warned areas. A tropical storm watch means that tropical storm conditions are possible within the next 48 hours. However, a tropical storm warning means that tropical storm conditions are expected within the next 36 hours and action to prepare for for the storm should be taken.

The main problem with this storm, along with dry air nearby, has been that there has been a strong field of shear that has eroded the southwestern side of any strong thunderstorms.

Other systems are tagged by the NHC in the Atlantic Ocean closer to Africa. The one with the best chance of developing is located 800 miles west of the Cape Verde Islands and has a chance for development into a tropical depression toward mid-week. Whether it has any impact on land is yet to be determined. This system continues to move to the west at 20 MPH.

A storm just southeast of the East Coast is also tagged by the NHC with a possibility of development and is currently affecting portions of the East Coast with cloud cover and humidity at the very least. Showers and a few storms are moving inland to the US from the storm itself as well. This storm has 0% chance of development.

In addition to the tropical weather, severe weather is possible today as the front that produced severe weather over the Northern Plains yesterday moves over Michigan and portions of the Ohio River Valley today. A tornado or severe thunderstorm watch has not been issued over this area, however, strong winds, a tornado and hail are all possible with today’s storms. It must be said that SPC’s chances of the above threats over Michigan and portions of the Ohio River Valley are much lower than yesterday’s.

Also, afternoon showers and storms with the threat of strong winds may occur over portions of Southeastern US. Similar to yesterday, strong winds follow the front and will reside around an adjacent low pressure system as hinted at by wind advisories over portions of the Northern Plains.

In addition, dry weather continues over portions of the Western United States and Alaska as forest fires continue to burn. Larger fires are in California, Washington, Idaho, Oregon and Montana. This year, according to the National Interagency Coordination Center, 7,448,217 acres are burning, which is above the year-to-date 10 year average of 5,350,800 acres. Much of this has been caused by warm and dry weather over the Western US along with thunderstorms that have a lack of rain, but plenty of fire-sparking lightning.

(As of August 23 2015)

A strong cold front will help to trigger strong to severe thunderstorms across portions of the Plains States and Mississippi Valley today. Showers and thunderstorms are already moving across parts of the North Dakota and Minnesota, with a few reports of hail up to one inch in diameter. As the front marches eastward, conditions will become more favorable for severe thunderstorms from the Upper Mississippi Valley into the Central and Southern Plains. The main threats are large hail, wind gusts to 70 mph or more and tornadoes.

Behind the front, strong northwest winds will usher unseasonably cool air into the Northern and Central Rockies and western portions of the Plains states. Wind advisories and high wind warnings are in effect for much of the region as wind gusts of up to 50-60 mph are likely today and Sunday. Some record low temperatures are possible Sunday morning in parts of Montana, Wyoming, and western portions of the Dakotas and Nebraska as low temperatures are expected to tumble into the 30s and lower 40s. Frost advisories have been issued for parts of western Montana.

Meanwhile, Hurricane Danny is starting to steadily weaken while approaching the Caribbean. As early early Saturday afternoon Danny was centered a little more than 600 miles east of the Leeward Islands, moving toward the west-northwest at 12 mph. After peaking as a Category 3 hurricane on Friday with winds near 115 mph, dry air and increasing wind shear have weakened Danny to a Category 1 with top winds near 85 mph, and additional weakening is expected. Tropical Storm Watches have been issued for much of the Northeastern Caribbean, including the islands of Antigua, Anguilla, Barbuda, Montserrat, St. Kitts, Nevis, Saba, St. Eustasius, St. Maarten, Guadeloupe, St. Barthelemy, and St. Martin. A tropical storm watch means that tropical storm conditions are possible within the next 48 hours.

Danny is expected to weaken into a tropical storm before crossing the islands. It should continue to weaken as it moves towards the US Virgin Islands and Puerto Rico. Some of the forecast models are showing the possibility that it could dissipate as it nears Puerto Rico. Others keep it as a very weak storm which then moves near Hispaniola and into the Bahamas, where conditions could become more favorable for it to start to strengthen again.

While the future track and strength are still very uncertain, one thing that is more likely is that Danny will bring beneficial rainfall to portions of the US Virgin Islands and Puerto Rico. The region has been in the midst of a severe drought for much of the year, with less than half of the normal yearly rainfall in some areas. While Danny won’t bring drought-busting rainfall to the region, every little bit that falls is beneficial.

Elsewhere in the Atlantic, a weak area of low pressure about 150-200 miles north-northwest of Bermuda will likely head out to sea over the next few days. There is a slight chance it could acquire tropical characteristics and become a tropical storm, but this seems unlikely. Much farther to the southeast, a tropical wave passing south of the Cape Verde Islands is producing disorganized shower and thunderstorm activity. As it crosses the Atlantic over the next several days, conditions should become more favorable for the system to develop. Yet another tropical wave will move off the Coast of Africa this weekend. This system could also start to get better organized as it crosses the Atlantic over the next week.

In the Central Pacific, both Kilo and Loke weakened to Tropical Depressions overnight, but they should both re-strengthen into tropical storms over the next day or two. Loke should remain a tropical storm while heading northward, possibly impacting Midway Island early next week. Kilo is the more immediate threat. Kilo should head northwestward while slowly strengthening over the next 24 hours. Sometime after that, a turn toward the north and eventually northeast is expected. Exactly where the storm makes the turn is critical to determining if there is a threat to parts of Hawaii. Right now it looks like there will only be a threaat to some of the westernmost islands, but if it turns earlier, that will change things. Conditions are favorable for Kilo to become a hurricane early next week.

Farther west, there are still two typhoons in the Western Pacific Ocean. Typhoon Atsani is expected to steadily weaken while heading out to sea well south and east of Japan. Tyhpoon Goni will bring gusty winds and heavy rain to parts of Taiwan today, before setting its sights on Okinawa and southwestern Japan tomorrow and Monday.