All Activity

I should have mentioned that - yea he’s writing for VA/MD specifically. We don’t have the prime atmospheric conditions VA will have. But that’s mostly for tornadic activity. The QLCS will mix down major winds. LWX mentions this in this afternoon’s write up which I have to say is much more in-depth than CTP’s. Granted however their entire coverage area is in the mod risk. CTP’s isn’t and they have a more dynamic atmosphere than we do. I don’t see tornadoes as much of a thing north of BWI. Once any earlier low stratus are scoured out, expect ample diurnal heating as temperatures rise into the upper 60s to low 70s. Prolonged south to southeasterly flow should also raise dew points into the upper 50s to low 60s. The seasonably warm/moist low-levels coupled by strong forcing aloft and cyclonic turning of the winds with height will make for a very active convective day. While the degree of vertical shear is impressive on its own (0-6 km values around 55 to 65 knots), this comes with more than sufficient buoyancy levels as surface-based CAPE values push into the 500 to 750 J/kg range. The shear/instability combination will be conducive to supercell development, particularly for any discrete cells that form ahead of a likely squall line. Additionally, the degree of deep-layer shear should make this more of a quasi-linear convective system (QLCS) which will be capable of tornadogenesis. Aside from any tornado risk, the strong cloud-bearing level winds should easily mix down in convective downdrafts. With 850-700 mb winds around 60-70 knots, any of this higher momentum air being transferred to the surface could yield surface wind gusts into the 65 to 75 mph range. Thus, SPC has a broad area of significant damaging wind potential (45-74%) advertised from I-81 eastward in their latest outlook.

We've got some decent icing on trees/raised surfaces. Temp down to 31F now. Thinking the next batch of precip moving in from S/SW should be snow. Well ahead of schedule (per models).

Wasn't Ian like the first one to start talking Derecho? I remember that day...if it wasn't for this site I would have been clueless on what was coming.

ORD just tagged 60. Should be near freezing there by midnight though

I just finished reading it, and it's an excellent write up. One thing, though, is that the biggest threat seems (per his post anyway) is south of the M-D Line. If I'm deciphering it right, things might not be as bad up this way as previously thought?

Can say we never had a high risk but derecho day should have been for sure.

This deformation band parked over the Twin Cities has picked up noticeably in intensity the last hour or so. More frequent winds too. Might bode well for those of you interested in its evolution over the next 12-18 hours. Measured about 11" otg here when I took the dog out at 1:30. Maybe another inch or so if these bands can stay for a while longer. My parents' house up in the NE corner of WI is at 24" from the band that just finally moved out. Crazy they're in line for another 6-12"+ once the storm ramps up again overnight

12z HRRR was trending colder, but it's currently colder now than it has it at 7 pm. Let's see how this works out.

Dont post anything if these runs come true.

0z HRRR last night. Upper 50s forecast for 7 pm. Didn't quite hit 55 before front went through.

Another person who cant read the pattern ahead. Its a possibility but its slight.

Eps also has some snow. Its a possibility with this upcoming pattern.

Yep, bit surprised at how fast temp has fallen and how early. Models last night were definitely keeping 50s around for several more hours.

One of the best posts you’ll read about this event

Wow... I did make a couple posts on Facebook for friends and family. First one was the graphical maps of the threats as depicted this morning. The second one quoted you anonymously (but indicating a friend's thoughts) a so as not to plagiarize, but to convey the potential severity of the event. Hopefully it's not as bad as what's possible. My caveat...whenever I post about storms (severe, snow, ice, etc) I usually end up jinxing it and eating crow.

Wausau still looks like the winner so far with 24 inches reported around 2 a few miles west of town. With the defo band still to come they may get to 30+ before it's all set and done.

The farm country in central Aroostook is closer and that area has some Midwest-type blizzards. (Not this year so far, however.)

Switched over to snow here. About 6 hours ahead of schedule

Afternoon AFD from LWX DISCUSSION... KEY MESSAGE 1...A strong cold front pushes across the forecast area Monday, bringing gusty winds and potential for severe thunderstorms capable of producing significant damaging winds and tornadoes. Surface high pressure shifts eastward over New England a CAD wedge bringing cooler conditions and cloudy skies to those east of the Blue Ridge. Southerly flow increases moisture in the atmosphere, with light rain showers observed on KLWX radar as of 3PM. Precipitation chances continue increasing as a potent low pressure system traverses across the Great Lakes into Canada, pushing the associated fronts across the Mid- Atlantic. The associated warm front lifts through the area overnight. A band of showers accompanies this warm frontal passage tonight. This comes with low clouds and continued breezy southeasterly winds. Depending on how quickly this boundary can lift north of the area, some residual stratus may linger across the Mid- Atlantic region on Monday morning. These should gradually scour out though ahead of the powerful cold front off to the west. Once this occurs, a more robust pre- frontal southerly wind overspreads the region. Outside of any thunderstorms, expect southerly gusts to around 25 to 35 mph, locally nearing 45 to 50 mph in the mountains. Gradient winds ahead of the front increase with a Wind Advisory in effect for the higher elevations on Monday. Wind gusts up to 55 mph are possible along the ridges. As an upper low gradually closes off near Lake Michigan, a shortwave begins to sharpen over the Mid-South midday Monday. As this trough pivots toward the East Coast, it begins to attain a negative tilt which will be conducive to further strengthening of the frontal system. Based on the forecast parameter spaces, the resultant severe weather aspect has a rather high ceiling in terms of impacts. Consequently, the Storm Prediction Center (SPC) has upgraded to a quite rare Day 2 Moderate Risk area, mainly along and east of the Blue Ridge Mountains. This is largely driven by the potential of widespread damaging winds, some of which could be significant in nature, as well as a tornado risk. Once any earlier low stratus are scoured out, expect ample diurnal heating as temperatures rise into the upper 60s to low 70s. Prolonged south to southeasterly flow should also raise dew points into the upper 50s to low 60s. The seasonably warm/moist low-levels coupled by strong forcing aloft and cyclonic turning of the winds with height will make for a very active convective day. While the degree of vertical shear is impressive on its own (0-6 km values around 55 to 65 knots), this comes with more than sufficient buoyancy levels as surface-based CAPE values push into the 500 to 750 J/kg range. The shear/instability combination will be conducive to supercell development, particularly for any discrete cells that form ahead of a likely squall line. Additionally, the degree of deep-layer shear should make this more of a quasi-linear convective system (QLCS) which will be capable of tornadogenesis. Aside from any tornado risk, the strong cloud-bearing level winds should easily mix down in convective downdrafts. With 850-700 mb winds around 60-70 knots, any of this higher momentum air being transferred to the surface could yield surface wind gusts into the 65 to 75 mph range. Thus, SPC has a broad area of significant damaging wind potential (45-74%) advertised from I-81 eastward in their latest outlook. With high-resolution models showing 3 to 6 hour differences in convective timing, there is still some uncertainty in how this all plays out. Most of the uncertainty is in regards to specific timing and instability potential. However, expect to be on alert for active weather from early Monday afternoon through much of the evening. All related activity races off to the east, some of which may be comprised of storm elements tracking eastward on the order of 45 to 50 mph. While not everyone sees a severe thunderstorm, the overall spatial coverage should be higher than normal. By Monday night, a post-frontal air mass pushes across the region with a rapid cool down in temperatures. This will lead to some upslope aided snow showers along/west of the Allegheny Front. Depending on how much moisture can be advected off the unfrozen portions of the Great Lakes, around 1 to 3 inches are possible through early Tuesday. Some global models show these spilling off the mountains toward the urban corridors. As such, will maintain light snow accumulations for locations east of the Allegheny Front.

Col front just pushed through. Down 6 degrees in the last 20 minutes

Yeah the trees are starting to get the freezing rain look right now. This could be an issue once the change over happens and the wind starts to pick up.

I’m just here for 1-2” of rain

Central Md

9.5 in December right before the pull-back. Nearly that (9+) later in Feb again right before the final thaw-off. Windy storms have made measurement a challenge but Harrison has had 8.5-9" since Friday, and I went from a bare balcony to now a 10" drift. Looks like mid-January again out there and I was ready for spring tbh. This from APX is not nice - so glad to miss this round of ice. 32F attm here at home. Unfortunately, whoever gets into the heavier freezing rain will likely see significant impacts...to include power outages and tree damage...with both of these being exacerbated by increasingly gusty winds during the day Monday. And, unlike last years historic ice storm, the ground temperatures are several degrees colder with this event...supporting very icy driving conditions as well.

Just 1 time… this would be a heck of a way to end the season…if only… Long duration with a track that even the the interior would love…