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virginia

Chasing a Possible Tornado Outbreak in NC today

Jason and I will be heading out to North Carolina around 8:00 this morning, and our target area that was picked 2-3 days ago is in the heart of the Moderate Risk area today, which includes a strong risk for tornadoes. A full chase log will be posted later today or tomorrow. It’s potentially going to be pretty epic.

Putting things into perspective, as of now there has been 6 deaths and 23 injuries from the tornado outbreak that occurred yesterday in the Southeast, and the threat for severe weather will be almost/just as significant today from central Virginia through Georgia. For those living in the risk area, please pay very close attention to the weather today, as these storms could form quickly and with very little warning, so do your best to avoid becoming another statistic in today’s severe weather.

 

Winter Storm Threat: Mar 30 (first/only? call)

This will probably be my only forecast for the event, but if things unfold drastically different in the morning I will make some adjustments. Models keep showing accumulating snow through northern VA into MD, but the thicknesses and surface temperatures just aren’t there to realize the snowfall potential. It’ll be a cold, cold rain for most.

 

Winter Storm Threat: Mar 26-27 (final call)

Decided to shrink down the snow totals a bit for the 1-2″ range on the NE edge and for the 2-4″ range for the eastern and southern areas. The 4-8″ actually expanded a bit, but got shifted further south. It will be a battle of boundary layer temperatures and thicknesses tonight.

 

Winter Storm Threat: Mar 26-27 (first call)

A suppressed storm system will move through the region Saturday into Sunday as a vort. max travels east-to-west over northern VA into MD. The SFC low is progged to move across the Carolinas, which will be favorable in getting a layer of below-zero temperatures at the SFC. However, it should be noted that the winds in the mid to upper levels will be out of the WSW across the southern parts of the region, which could allow for a nose of above freezing temperatures to move into southern WV and VA. This will cause mixing issues with sleet and freezing rain that will hurt the overall snowfall totals across the southernmost parts of the region. The wintry mix will extend into northern NC before changing over to all rain in central NC.

 
I am siding with the GFS snowfall contouring for now since it seems like it has a better handle on the mid-level temperatures and the warm nose that will move through the southern parts of the region. I also did account for a slight northerly trend in the eastern parts of the region, which is consistent with trends that yesterday’s storm experienced further north into NY and southern Canada, where accumulations occurred a good distance further north than anticipated.

Risks: A northern trend could bring the 1″+ totals into southern PA, and a colder solution as depicted on the NAM could bring the rain/snow line a bit further south towards the VA/NC border.

Mid-Atlantic Discussion – Mar 23, 2011 and this weekend

TOMORROW:

A rather unusual severe weather setup as a low pressure system rides along a frontal boundary that is NW-SE oriented from central OH into central MD. Warm-sector instability on the order of 500-1000+ J/kg SBCAPE will develop over WV and western VA during the afternoon, which will help initiate a few areas of showers and storms. A convergence area over the Appalachians will help trigger storms early, with better instability upstream ahead of the southward-moving cold front that will move through OH and WV during the late afternoon and early evening. Things will look a little messy on radar at first, but eventually some strong/severe cells will form in the westernmost parts of the region. The main threat from these storms will be hail and wind damage, with an isolated threat for a few tornadoes. Speed shear is good with this system, but winds will be largely unidirectional, which will hinder tornadic development. Upper-levels are somewhat favorable as left-exit region divergence and some support from the 500mb vort. provide good synoptic lift.

As these storms push east into the Apps. and coastal plain, they will likely lose some intensity as the surface instability wanes. However, elevated instability should be sufficient to maintain thunderstorms with hail (maybe severe) and gusty winds (likely not severe) as the storms reach the DC/BWI region in the early evening. Depending on the amount of the elevated CAPE, storms could maintain themselves rather well and provide the area with a good lightning show.

Chase-wise, I’m considering taking I-68 to Morgantown, WV and then waiting to see where storms initiate. Should storms end up more favorable to the south, it will be a quick drive on I-79 towards Charleston, WV to get into better position.

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THIS WEEKEND:

It appears as though the cold air is a lock for Friday and Saturday. A storm system passing by to our south on Saturday is expected to bring some cold rain and possibly snow into the region (…so much for that Southeast ridge). Should the colder temperatures and precipitation verify, a swath of 1-3″ or more of snow is possible in the northern half of the region. Timing the precipitation with the colder temperatures will be key in getting widespread snowfall to occur, so this system will be revisited later this week and could include a snowfall forecast map.

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I will forgo this week’s What to Watch Fore(cast) as 1) I am already behind and 2) there’s plenty to track regionally this week.

Tornadoes confirmed in northern VA from Thursday’s storms

Two tornado warnings with to confirmed tornadoes… one EF-0 and one EF-1, occurred last Thursday as a line of thunderstorms moved through central Virginia. Jason was out to document the flooding, but he found himself going after the tornado-warned storms as daylight faded. In the end, he got close, but he did not end up seeing a tornado.

The report: http://www.erh.noaa.gov/er/lwx/events/20110310tor.php

The description:

…TORNADOES CONFIRMED IN BEALETON VIRGINIA AND CHANTILLY VIRGINIA…

LOCATION…BEALETON IN FAUQUIER COUNTY VIRGINIA
DATE…MARCH 10 2011
ESTIMATED TIME…617 PM TO 620 PM EST
MAXIMUM EF-SCALE RATING…EF1
ESTIMATED MAXIMUM WIND SPEED…90 MPH
MAXIMUM PATH WIDTH…75 YARDS
PATH LENGTH…4 MILES
BEGINNING LAT/LON…38.5750N / 77.7605W
ENDING LAT/LON…38.6189N / 77.7013W
* FATALITIES…NONE
* INJURIES…NONE
* THE INFORMATION IN THIS STATEMENT IS PRELIMINARY AND SUBJECT
TO CHANGE PENDING FINAL REVIEW OF THE EVENT(S) AND
PUBLICATION IN NWS STORM DATA.

 

Mid-Atlantic – The Week Ahead (Feb 27 – Mar 6)

Temperatures will be above normal today as the sun peaks through scattered clouds southerly winds push warmer air into the region. The birds are chirping this morning as spring tries to get going early in our region. Enjoy today, because tomorrow will be a different story.

***** IMPORTANT INFORMATION CONCERNING MONDAY’S WEATHER *****

 
After a miserable but warm start to Monday, skies should clear up a bit as temperatures climb into the upper 60s to lower 70s ahead of a rapidly approaching storm system. This system is expected produce plenty of severe weather across the region, with most of the concern centered on severe wind as storms line out, with some bowing segments. The storms should start moving across the Appalachians in the early afternoon, approaching the BWI/DC/RIC areas in the late afternoon or early evening. There is also some tornado and hail potential with these storms as a decent amount of thermal instability (CAPE of 500-1000 J/kg) and excellent wind shear fuel the thunderstorms. The SPC currently has a 30% severe risk (high-end Slight Risk) over most of the region, but I wouldn’t be terribly surprised if it got bumped to a low-end Moderate Risk somewhere in the region (central/southern WV/VA and DC/MD?). Yes it’s February, but this storm is more of an April-type system for the region, and should be taken seriously. Do not let your guard down on this one.

Following the Monday storm will be a nice break in the weather as mostly sunny and seasonal weather takes over. Tuesday through Thursday should be pretty nice as we start the month of March and meteorological spring along with it. Friday will be a bit gloomier as clouds and a few rain showers pop up over the region. This will continue into Saturday as a very complicated pattern evolves over the weekend. The models begin to SUBSTANTIALLY diverge with a late weekend storm system approaching the region from the west. The GFS currently has a storm moving through Saturday night into Sunday, while the ECMWF takes a much slower and perhaps more complicated look at this system, bringing it through much later (late next Monday). Right now I would go with a chance of rain showers Saturday and Sunday, but it is probably the most complicated system I’ve seen this season (and there’s been plenty of them), so confidence is very, very low.