Archive for Nebraska
Thoughts On Afternoon Data And The Storm For Tuesday Through Wednesday Night
Posted by: | Comments6:26 PM
I don’t think anyone can argue that the model guidance has warmed. There has been little shift in the actual storm track, but the low pressure systems that impact the forecast area appear to have stronger WAA at the mid levels are the very least. There is a lot to consider here, but I want to stress that I won’t be forecasting exact snow, ice, nor rain totals at this time.
The first aspect to consider is the strength of the warm air advection on Tuesday. Before any change over even begins, I think the forecast area will be under the influence of a prolonged light to moderate snow fall from late Tuesday morning through early Wednesday morning as the WAA continues to build. The model guidance just does not have the ability to forecast accurate QPF amounts for this type of lifting, usually under performing in these types of events. A perfect example is this evening where almost no precipitation was forecasted three days ago through the Ohio Valley and much of Pennsylvania, and here we are with light snow over those locations and moving eastward. More importantly though, take a look at the pattern right now. Let’s look at the water vapor image together.
Notice where the moisture is moving from and to. The moisture is coming from the Tropical Pacific and off the California coast. Due to the weakening trough/closed low, the moisture then moves north into the central Rockies. From there, the moisture and the disturbances within the moisture is forced due east through the central/northern Plains, Upper Mid West, Ohio Valley, and into the Mid Atlantic. This pattern will not change much from now through Wednesday morning until the main energy over the Southwest begins to eject east and becomes part of the northern branch. Before that point though, a steady stream of mid level moisture will move over fresh cold air over the forecast area. Now, take a look at the latest radar. I would also point out that precipitation is starting to develop over Nebraska, Illinois, the Kentucky Valley, the southern Ohio Valley, and over Virginia. This was not expected, but is it happening.
My point here is I think the forecast area will see a good amount of snow throughout the forecast area before any change over. I also think the change over to any liquid precipitation will be more expected over southern New Jersey from basically central Ocean County through Cape May County. The average of all model guidance (and I’m now starting to use SREF guidance as well) suggest a period of light to moderate snow to develop from late Tuesday morning through early Wednesday morning. A change over to rain is expected over extreme southern New Jersey. I am not confident of a change over from frozen to liquid precipitation for Philadelphia itself nor central New Jersey. In fact, we’ve seen all winter how the model do a great job handling the mid levels of the atmosphere, but not so well with the low level cold air and that’s under the environment of little snow pack over the coastal plain. So I would hazard against the idea of going snow to rain so quickly just away from the coast.
The area at this time that looks to get the best accumulating snowfall will be locations just north of Philadelphia through central New Jersey into the New York City metro. This area includes northeastern Pennsylvania through the southern Hudson Valley and Connecticut. This is my preliminary thoughts, and I will hold off on snow maps at this time until I get a better handle on the low level thermal fields in this situation. I also want to again repeat, I know I sound like a broken record, that I still expect light to moderate snow to fall on Tuesday afternoon through early Wednesday night, which still gives the entire forecast area a good potential for snowfall amounts over 6″+ before any change over. Further, the stronger WAA also would suggest strong dynamics and thus a period of heavy snowfall ahead of a change over. So there is still a lot to iron out here, especially in terms of mesoscale forcing.
Those are my thoughts for now. I am keeping the alert level the same and will wait until we are a bit closer to the event, likely tomorrow morning.
-- Weather When Posted --
- Temperature: 26°F;
- Humidity: 35%;
- Heat Index: 26°F;
- Wind Chill: 18°F;
- Pressure: 30.3 in.;
Minor Snow For Sunday Night Into Monday
Posted by: | Comments8:32 PM
For the past several days I have advertised the idea of a light snow developing Sunday night through Monday morning for southern portions of the forecast area, specifically for southern New Jersey.
Moisture is now starting to develop over Nebraska and expand eastwards towards the north/central Plains. As this moisture moves eastwards towards the Ohio Valley, a mid level disturbance will intensify. Tomorrow afternoon, the disturbance will begin to interact with the Appellation Mountains and the moisture will begin to dry out due to a typical down sloping effect. As the disturbance begins to interact with the Atlantic, moisture will redevelop over southeastern Pennsylvania, central and southern New Jersey, and eventually the immediate New York City metro area. The following precipitation map will show what I think will be the impact areas.
Grey: No precipitation is expect in these areas.
Light Blue: Generally snow flurries are expected with possibly a dusting at most by Monday morning.
Blue: The mid level forcing will be more organized in these areas as a band of light snow develops over this location by early Monday morning. The snow accumulations are generally expected to range from a dusting to an inch. An isolated two inches will be possible should a small band of moderate snow develop due to some weak Ocean enhancement at 850 MB. This is not likely, but still possible.
-- Weather When Posted --
- Temperature: 24°F;
- Humidity: 35%;
- Heat Index: 24°F;
- Wind Chill: 12°F;
- Pressure: 30.22 in.;
Severe Weather Threat Today
Posted by: | Comments
The main threat for severe weather will remain over the southern Plains as a strong upper low and jet maximum produces strong vertical wind shear over the region. Although the low level clouds may inhibit instability initially over the region, by the afternoon the cap should be broken with a significant threat for large hail, tornadoes, wind gusts exceeding 60 mph, heavy downpours, and cloud to ground lightning can be expected in the strongest thunderstorms.
Severe weather is not expected over the rest of the country, however thunderstorms will still be possible over other locations.
Over the northern Plains, the digging trough will support weak wind shear, divergence aloft, and low level convergence which will lead to showers and thunderstorms along an advancing cold front.
Meanwhile, an upper low rotating through the eastern Great Lakes and towards the Northeast will produce unstable conditions over the region. Showers and thunderstorms will develop in the afternoon as cold air aloft supports the development of hail, strong wind gusts over 50 mph, and heavy downpours. The showers and thunderstorms will be scattered in nature.
-- Weather When Posted --
- Temperature: 64°F;
- Humidity: 93%;
- Heat Index: 64°F;
- Wind Chill: 64°F;
- Pressure: 29.75 in.;
Severe Weather Today
Posted by: | Comments
Two areas of focus today for the severe weather.
The first is over the Southeast coast. South Carolina and Georgia will be in the warm sector of a developing low pressure system over northwestern Georgia. A strong upper disturbance will dig and turn through the forecast area which will produce strong lifting over the region. Meanwhile, strong isentropic lifting will lead to the addition of plenty of heat and moisture until the area. Finally, the veering winds from the surface to 500 MB will produce strong vertical wind shear, which will support the development of turning thunderstorms. The strongest thunderstorms will be capable of strong wind gusts, isolated tornadoes, large hail, and heavy rainfall.
A strong disturbance and a weak trough of low pressure at the surface will move through the eastern Rockies and western central Plains. The disturbance will produce veering winds from the surface to 500 MB, which will produce strong wind shear over the region. The strongest thunderstorms will be capable of strong wind gusts, large hail, heavy downpours, and isolated tornadoes.
-- Weather When Posted --
- Temperature: 60°F;
- Humidity: 82%;
- Heat Index: 60°F;
- Wind Chill: 60°F;
- Pressure: 29.84 in.;
Severe Weather Today
Posted by: | CommentsThe most organized area of severe weather will be found over the north-central Plains. A trough will dig into the region, which will send a series of strong disturbances south through much of the area. As a result, wind shear will increase as cold temperatures aloft combine to destabilize the atmosphere. The strongest thunderstorms will be capable of large hail, heavy downpours, wind gusts exceeding 60 mph, and an isolated tornado.
A dry line along with a surface cold front will destabilize the atmosphere over the Red River Valley of Oklahoma and Texas. Wind shear will increase over this region as dry air aloft moves towards central Oklahoma. The majority of the thunderstorms will be weak, however an isolated severe thunderstorm is possible with the strongest capable of strong wind gusts, heavy downpours, frequent lightning, and an isolated tornado.
Finally, the upper low rotating through the Northeast will continue to produce an unstable environment with warm, moist air at the surface and cold, dry air aloft. Although precipitation is expected to be widely scattered, the nature of the upper level system would suggest the potential for showers and thunderstorms in the afternoon. The strongest thunderstorms will exhibit large hail, heavy downpours, and damaging wind gusts over 50 mph.
-- Weather When Posted --
- Temperature: 57°F;
- Humidity: 93%;
- Heat Index: 57°F;
- Wind Chill: 57°F;
- Pressure: 29.8 in.;
Severe Weather Today
Posted by: | Comments
The majority of the severe weather today will be focused over the central Plains to the mid Mississippi Valley and over the Tennessee Valley. A series of disturbances will enhance the cold front in these locations to produce showers and thunderstorms. An MCS currently over Kansas will also enhance the frontal boundary at the surface over these locations. The mid and upper level disturbances will enhance vertical speed and directional shear, which will lead to a favorable environment for isolated tornadoes, large hail, wind gusts over 65 mph, and heavy downpours.
Another strong disturbance will move through New England and the northern Mid Atlantic through the day with showers and thunderstorms. The main threat from these thunderstorms will be the very heavy rain with rainfall amounts over an inch possible in many locations.
-- Weather When Posted --
- Temperature: 71°F;
- Humidity: 94%;
- Heat Index: 71°F;
- Wind Chill: 71°F;
- Pressure: 29.84 in.;
Severe Weather Today
Posted by: | Comments
The bulk of the severe weather will be concentrated around the Mid West, Ohio Valley, eastern Great Lakes, and eventually the Mid Atlantic.
A trough will continue to dig into the eastern United States with a series of strong mid level disturbances moving through the areas described above. The strong disturbances will enhance the thunderstorms located along the cold front over the Mid West and the stationary front over the Southeast. The warm front will move north while the cold front moves east over the next 24 hours, leading to a clash of air masses. The combination of strong upper level and mid level winds and divergence aloft will lead to significant vertical directional and speed shear over the region, which will support the potential for an isolated tornado, wind gusts over 60 mph, and large hail. The thunderstorms will also be capable of frequent cloud to ground lightning and heavy downpours. Localized flooding will be possible in these thunderstorms.
As the thunderstorms move east into the Mid Atlantic, they are expected to weaken below severe levels, but remain a threat as the thunderstorm form into a line over night. Although the majority of the severe threat will diminish, the thunderstorms will still be capable of producing strong wind gusts to 55 mph, hail, heavy downpours, and frequent lightning.
Meanwhile, isolated tornadoes will be possible over the northeastern coast of Texas and southwestern Louisiana as Tropical Storm Edouard makes landfall later this morning. The main threat from Edouard will be the heavy rain and sustained winds of 65 mph with gusts to 80 mph. However, an isolated tornado can develop as bands of thunderstorms move on shore and wind shear increases from the surface to 850 MB.
Finally, a mid level disturbance will interact with up sloping winds over eastern Wyoming, western Nebraska, and northeastern Colorado to produce strong to severe thunderstorms. The thunderstorms will be capable of very heavy rainfall, frequent lightning, and wind gusts over 65 mph.
-- Weather When Posted --
- Temperature: 66°F;
- Humidity: 77%;
- Heat Index: 66°F;
- Wind Chill: 66°F;
- Pressure: 29.98 in.;
Severe Weather Today
Posted by: | Comments
The north-central Plains, Mid West, and Great Lakes will be very active today with severe weather. There are a lot of different mid level disturbances enhancing showers and thunderstorms over the region this morning including a strong MCS over the Dakotas. However, the overall theme with the severe weather threat through the evening hours will be the digging trough over the Great Lakes over the next 24 hours. As the trough digs into the region, upper level and mid level winds will increase producing strong vertical directional and speed shear over the region, which will support the development of tornadoes and wind gusts exceeding 60 mph. Additionally, the combination of warm, moist air at the surface interacting with cold, dry air aloft will lead to severe thunderstorms capable of large hail, especially over eastern South Dakota, eastern Nebraska, and much of Iowa.
Meanwhile, the approach of Tropical Storm Edouard will also bring the increase potential of severe thunderstorms capable of an isolated tornado, wind gusts exceeding 65 mph, and very heavy downpours. Significant flash flooding will be possible in some of the strong thunderstorm bands this afternoon.
Additional information can be found at the SPC.
-- Weather When Posted --
- Temperature: 68°F;
- Humidity: 72%;
- Heat Index: 68°F;
- Wind Chill: 68°F;
- Pressure: 29.95 in.;
Severe Weather Today
Posted by: | Comments
The focus of the severe weather this afternoon will be over the northern Plains. A building heat ridge over the southern and central Plains will send hot and moist air into the lower levels of the atmosphere in this region. Meanwhile, a trough will begin to dig over the northern Rockies, which will send a series of disturbances through the northern Plains. The combination of warm, moist, unstable air at the surface, cool, dry air aloft, increasing wind shear, and moderate to strong mid level disturbances will set up an environment perfect for severe weather. The strongest thunderstorms will be capable of large hail, wind gusts over 65 mph, isolated tornadoes, and very heavy downpours.
The rest of the nation will be generally quiet with only the usual afternoon thunderstorms along the Gulf Coast and some monsoonal showers and thunderstorms over the Southwest and central Rockies.
-- Weather When Posted --
- Temperature: 75°F;
- Humidity: 57%;
- Heat Index: 77°F;
- Wind Chill: 75°F;
- Pressure: 29.85 in.;
Severe Weather Today
Posted by: | CommentsAn active day of severe weather can be expected due to several different disturbances over the United States.
The remnants of Dolly continue to move through the southern Plains, which will produce wide spread showers and thunderstorms from southern Nebraska through central Texas. The greatest threat from these thunderstorms will be the heavy rain, which can lead to flash flooding, wind gusts over 55 mph, and frequent lightning.
A weak disturbance over the eastern Rockies on the back side of a depart trough will support widely scattered strong to severe thunderstorms. Winds will upslope off the eastern Rockies to produce lifting over eastern Montana, eastern Wyoming, western South Dakota, and western Nebraska. Meanwhile, the disturbance will enhance vertical wind shear, which may lead to an isolated tornado. The strongest thunderstorms will be capable of frequent light, heavy downpours, wind gusts over 65 mph, and large hail.
Finally, a strong trough over central Canada will progress east towards Ontario and the Great Lakes today. The trough will produce strong divergence aloft and strong lifting at 500 and 700 MB due to impressive PVA. The short wave disturbances in the trough will enhance vertical direction and speed shear over the region, while colder temperatures aloft will also increase the potential for large hail. Finally, the lower level of the atmosphere is very unstable this morning with warm, humid conditions. The strongest thunderstorms will be capable of large hail, wind gusts exceeding 65 mph, an isolated tornado, and heavy downpours.
Freehold
77°
Philadelphia
81°
Sussex
73°
Allentown
77°
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