George BM

Don't completely sleep on this Tuesday either. There could be some low-topped convection with limited CAPE along and just ahead of the cold front. Steep low-level lapse rates and fairly fast-flow aloft could translate to some of the convection having strong wind gusts.

This shows that we at least have a non-zero severe chance through the end of April.

Even the April 6, 2017 had fairly widespread strong winds and seven EF-0 tornadoes in northern VA... this with less than 250J/kg MUCAPE. That June 13, 2013 event could have been a memorable event area-wide if the morning MCS didn't hamper things. It was also the last time we had a moderate risk in the immediate region though it was downgraded to a SLGT at 1630z due to said morning MCS leaving us with AOB 1000 J/Kg MLCAPE. This is my opinion (not an expert): When dealing with a W/NW flow event with a fairly strong low-pressure system within the flow there will very often be a morning/early day MCS. This is because the previous days storms that develop in the Midwest often grow upscale during the evening and are able to survive the whole night due to the better dynamics and CAPE. With the forward speed that these MCSs usually have they very often reach us during the morning hours. An ideal thing with these regimes would be either the timing being a few hours faster so that we can get more midday/solar noon sunshine to destabilize the atmosphere more quickly for any later day activity (easier option) or a heat-dome already being in place so that any morning event would stay to the north while the low-pressure system approaches from the W/NW spawning another MCS (or just decent storms in general) during the afternoon to cruise through the region during the afternoon/evening (harder to pull off option).

Thank you both for the replies.

Sorry for the novice question but how do I read this? Is this showing the expected surface wind speed and direction at various times?

Mesoscale Discussion 0360 NWS Storm Prediction Center Norman OK 0426 PM CDT Sun Apr 12 2020 Areas affected...south-central and southeast Mississippi Concerning...Tornado Watch 106...107... Valid 122126Z - 122200Z The severe weather threat for Tornado Watch 106, 107 continues. SUMMARY...Based on recent radar and environmental data, a violent tornado with potential peak winds of 170 to 205 mph (EF4-EF5) is likely ongoing. THIS IS AN EXCEPTIONALLY RARE EVENT. DISCUSSION...An intense supercell will continue to move through a favorable environment over south-central Mississippi, characterized by 0-1 km SRH around 400 m2/s2 and MLCAPE near 2000 J/kg per latest mesoanalysis data. Recent radar signatures from KLIX as of 2112Z reveal an intense supercell characterized by a 0.4 degree rotational velocity of at least 70 kt. A tornadic debris signature has also been noted on recent radar scans. These signatures are occurring in an environment characterized by STP greater than 7. Previous signatures within similar environments produced tornado-damage-estimated wind speeds from 170 to 205 mph and confidence is high for a likely violent tornado. A long-track tornado is expected to continue based on the rotational velocity duration and the storm moving within a favorable downstream environment.

Also RAP'd.

I know that the post-frontal winds may be strong but... though we are not expecting much of this atm pre-cold front can you imagine if we somehow got a break in the clouds late tomorrow morning with those kind of low-level winds overhead?... Of course this is more speculative than me predicting it.

Even the long-range 6z hrrr (Yes, all caveats apply... end of range) shows 45-50 kt post-frontal gusts across the region. I usually find the hrrr more in line with what happens during synoptic wind events during the daylight hours. All long-range caveats aside... it looks windy tomorrow.

A rare Day 3 update. Day 3 Convective Outlook AMEND 1 NWS Storm Prediction Center Norman OK 0211 PM CDT Sat Apr 11 2020 ...Virginia through central and eastern Pennsylvania and New Jersey... Have expanded the SLGT risk farther north into this region. Areas of rain and thunderstorms will likely be ongoing north of a warm front from PA and NJ into southern New England. This activity will shift northeast during the morning allowing modest destabilization to occur in the pre-frontal warm sector with MLCAPE from 400-800 J/kg. Storms are expected to redevelop along cold front and in association with deeper forcing accompanying the northeast-ejecting shortwave trough. Wind profiles with 50+ kt effective bulk shear along with large 0-1 km hodographs will promote a threat for organized storms including supercells capable of damaging wind and a couple of tornadoes.

Psssst.... June 23rd is around the block.

The "obviously overdone severe-weenie" 6z 3kNAM said we get a supercell through DC tomorrow afternoon.

A pre-climo NW flow regime w/ potentially steep mid-level lapse rates... We watch.

Thank for the reply. Yeah the latest long-range HRRR has some loltastic soundings. I mean check out this uncontaminated sounding below. I mean 3,000+ J/kg MLCAPE, LI near -10 with effective bulk-shear around 100kts. Lol!

Now this is not for our region (SW of Chicago)... AND it's just one run from last night's 0z NAM at range but... it's not too often that you see 100+ knot EBWD with 1,000+ J/kg MLCAPE. (Also, please ignore the fact that I accidentally called these files as the 3kNAM... the images below are actually from the lower-res NAM) The following is just me thinking out loud. I'm not making assumptions about the severe threat over yonder. I wonder if 1,500+ J/kg mlcape and LIs of -5 to -6 would be enough instability for storms to not get ripped apart by this kind of shear verbatim (Is CAPE fat enough?). Yeah 1,500 J/kg mlcape is not all that weak but... that shear though... Of course I'm not trying to take away from the high-ceiling that storms will have should they take advantage of their environment. @high risk @csnavywx thoughts on this? Also I realize now that I have a problem with using too many ellipses and parentheses.

Yeah. March 3rd is getting a tornadic streak lately.

The Tennessee tornado becomes the first violent tornado of the year in the US.

Clearing.

A low risk of some thunder and perhaps some gusty winds tomorrow depending on the amount of sunshine we can get. Low-level lapse rates look steep... with mid-level lapse rates looking somewhat steep as well. And FWIW... SPC doesn't even have us in a 10% thunder risk for tomorrow so...

If the surface low of that mid next week system can track just off to our northwest lots of models have some impressive wind fields. CAPE would be the main question though mainly because of warmer low/mid-level temperatures... and also climo in general (it's still on the early side)... Though the February 7th system probably has a few choice words for me about that "climo" statement.

They made a reference to that event in the 1630z update.

Day 2 MRGL wind in southern zones.

@Kmlwx Indeed I am. June 23rd is around the corner.

Knowing our luck... probably. My ideal pattern over the next couple months, say through June, would be for this pattern to last through early May. Then the NAO will tank to strongly negative from say May 10th onward while a ridge builds into western Canada over a trough in the western US (-EPO/-PNA) allowing for a ridge to build over the southern 1/2 to 2/3rds of the nation east of the Rockies while a trough gets locked in between the Great Lakes and Hudson Bay in response to the ridge nosing into western Canada(-EPO) AND the ridge over Greenland (-NAO). Think May 30-31, 1998 but through the Ohio Valley and Mid-Atlantic instead.

I just hope that we can keep this general pattern over the next couple of months.