yoda

Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1112 AM CDT Thu Oct 31 2019 Valid 311630Z - 011200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS PARTS OF NC...VA...WV...MD...DC...PA... ...SUMMARY... An extensive squall line of strong to severe thunderstorms is expected to develop during the late afternoon into this evening, near and east of the Appalachians from parts of New York to the Carolinas. At least a few tornadoes and scattered to widespread damaging winds are possible. ...Northeast to the Carolinas... Have upgraded peak probabilities for both wind and tornado hazards with an active period of severe weather anticipated later this afternoon into the evening. An amplifying shortwave trough now over IL will accelerate east-northeast toward the Saint Lawrence Valley through tonight toward PA/NY, while taking on a more neutral-to-negative tilt with peak 500 mb wind speeds exceeding 120 kt. Strong surface cyclogenesis is expected in advance of the amplifying trough, with a cyclone moving from OH to far southern QC by early Friday. South of the deepening cyclone, a strong cold front will sweep eastward across the Appalachians this afternoon, reaching the Atlantic coast overnight. The cold front will be the primary focus for severe thunderstorms through this evening. Northward advection of low-level moisture will continue with mid 60s boundary-layer dew points up the OH Valley west of the Appalachians and across southeast PA to coastal southern New England. Poor low to mid-level lapse rates amid widespread clouds will hinder destabilization with northern extent in the Northeast. Richer low-level moisture (upper 60s to low 70s boundary-layer dew points) and some surface heating in cloud breaks will support a confined plume of MLCAPE between 750-1500 J/kg across parts of VA into the Carolinas at peak heating. Within the warm sector, vertical shear will increase in response to the approach and deepening of the mid-level trough/surface cyclone. Long hodographs with effective bulk shear of 50-60 kt are expected, and there will also be enlarged low-level hodograph curvature for numerous rotating storms amid effective SRH of 300-500 m2/s2. Strong linear forcing for ascent along the cold front will be the primary focus for storm development, mainly east of the Appalachians later this afternoon/evening. The strong linear ascent will favor upscale growth into a squall line, though strong deep-layer shear and enough east component to storm motions should allow embedded supercell structures to persist. The modest buoyancy and very strong 850-700 mb flow will favor damaging winds as the primary threat. These could be potentially widespread within longer-tracked bowing segments. At least a few tornadoes are also anticipated with embedded supercell and mesovortex structures, particularly from central NC to central MD. The severe threat will diminish during the late evening to overnight given an increasing dearth of surface-based instability with east/northeast extent. ..Grams/Wendt.. 10/31/2019

10% TOR PROBS AND 45% WIND PROBS ON 1630 OTLK

First TW of the day issued from KMRX in extreme SW VA

Mesoscale Discussion 2128 NWS Storm Prediction Center Norman OK 1012 AM CDT Thu Oct 31 2019 Areas affected...Parts of eastern North Carolina...northeastern Tennessee...southwestern Virginia...far eastern Kentucky...West Virginia and southwestern Pennsylvania Concerning...Severe potential...Watch likely Valid 311512Z - 311715Z Probability of Watch Issuance...80 percent SUMMARY...A more substantial increase in potential for severe wind gusts, and perhaps isolated tornadoes, is expected with a developing line of storms during the 1-3 PM EDT time frame. One or more watches probably will be needed within the next couple of hours. DISCUSSION...Although mid/upper-level lapse rates across much of the region are more or less moist adiabatic, latest objective analysis suggests that boundary layer warming and moistening are contributing to at least weak destabilization along the western slopes of the Allegheny Mountains. Mixed-layer CAPE may not become much more than roughly 500 J/kg, but this is expected to occur in the presence of strengthening lower/mid tropospheric wind fields, as deepening of the surface cyclone (now centered near Columbus OH) proceeds more rapidly through early to mid afternoon. Model forecast soundings indicate south to southwesterly flow intensifying to 50-70+ kt, just off the surface through around 500 mb, as the strengthening surface cold front advances toward the Alleghenies. This is expected to coincide with increasing lift along/ahead of the cold front, aided by forcing for upward vertical motion ahead of a vigorous short wave trough gradually pivoting east of the the Mississippi Valley, to support an intensifying line of thunderstorms. It is possible that this may be gradually underway across parts of northeastern Tennessee through eastern Kentucky and southeastern Ohio, but a more notable increase/intensification seems more likely during the 17-19Z time frame, before gradually spreading eastward into/through the Appalachians. As convection intensifies, downward momentum transport in downdrafts will contribute to increasing potential for damaging convective surface gusts. Large low-level hodographs could also support supercell structures along and perhaps just ahead of the developing line of storms, with a risk for tornadoes. ..Kerr/Grams.. 10/31/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...CTP...LWX...RNK...PBZ...RLX...GSP...MRX...JKL...

12z 3km NAM has a mean squall line/QLCS that comes roaring through the LWX CWA -- around 23z for I81 corridor... 01z along the BR... and 02z through I95 corridor

lol 12z NAM throwing out PDS TOR down by EZF and and just south of Warrenton on the soundings on pivotalweather for 00z in the possible hazard type

12z NAM pushing a little harder on the potential TOR threat this evening... gets SBCAPE up to near 800 J/KG and MLCAPE near 1000 J/KG at KIAD at 00z with EHI at 3.0 and 1km SRH at 470 m2/s2. STP is 6.6 and LCLs are fairly low - under 400m

Right above you

Well this post aged well... there was a gem from Strasburg in Game 6 and the Nats bats came alive in both Game 6 and 7... congrats to the Nats on becoming WS Champs

@high risk @Kmlwx @Eskimo Joe ENH risk on 0600 Day 1 OTLK... rather large 5% tor and 30% wind probs

Yes, that's correct

I would believe so... is that correct @high risk?

Ton of low level shear at 00z THUR at KDCA on the 00z NAM sounding... look at the winds turn, damn... also 60kts at 900mb is yikes

Seeing some SRH values approaching or exceeding 400 m2/s2 at the 1km level... hodographs are decently curved as well around 00z

I hear schools are closing tomorrow

So... who's staying up tonight for the 0600 SPC Day 1 OTLK at or just before 2 am? Anyone?

Subtropical Storm Rebekah Discussion Number 1 NWS National Hurricane Center Miami FL AL192019 500 PM AST Wed Oct 30 2019 Cloudiness and showers associated with a small low pressure system embedded within a larger non-tropical low over the north-central Atlantic have become better organized during the day. The cyclone has a broken convective band that wraps about halfway around its eastern semicircle, with a small area of central convection near its center. The cloud tops within the convection are not particularly cold and the system is co-located with a large upper-level low, so it is initially designated as a subtropical cyclone. The intensity is assessed as 40 kt based primarily on earlier ASCAT data. It is worth mentioning that the system also has some characteristics of a tropical cyclone, since the radius of maximum winds is not very large and the system has some moderate central convection. Much like Pablo just a few days ago, Rebekah is currently rotating around a larger non-tropical low pressure system. The initial motion estimate is 080/11 kt, but an east-northeastward motion is expected later tonight. The track model spread is larger than normal and confidence in the track forecast is low, though most of the models generally show Rebekah turning back toward the east by early Friday, followed by a turn toward the east-southeast until it dissipates later this week. On the forecast track, the center of Rebekah is forecast to approach the western-most Azores early Friday as a post-tropical/extratropical cyclone. The intensity guidance unanimously forecasts that Rebekah will change little in strength during the next 24 h, though given the small size of the cyclone, some short-term fluctuations are possible tonight. Most of the dynamical models then forecast that Rebekah's convection will decrease substantially by early Friday, likely due to a combination of colder SSTs and unfavorable upper-level winds. The cyclone is therefore forecast to become post-tropical around that time, and gradual weakening is expected. Rebekah will likely dissipate by the weekend, if not sooner. Since Rebekah is not currently forecast to be a tropical or subtropical cyclone when it nears the Azores, hazard information can be found in regular products issued by the Portuguese Institute for the Sea and Atmosphere (IPMA) for those islands. FORECAST POSITIONS AND MAX WINDS INIT 30/2100Z 38.3N 40.7W 40 KT 45 MPH 12H 31/0600Z 39.0N 38.4W 40 KT 45 MPH 24H 31/1800Z 39.9N 35.0W 40 KT 45 MPH 36H 01/0600Z 39.8N 31.3W 35 KT 40 MPH...POST-TROP/EXTRATROP 48H 01/1800Z 38.9N 26.3W 30 KT 35 MPH...POST-TROP/EXTRATROP 72H 02/1800Z...DISSIPATED $$ Forecaster Zelinsky

BULLETIN Subtropical Storm Rebekah Advisory Number 1 NWS National Hurricane Center Miami FL AL192019 500 PM AST Wed Oct 30 2019 ...SUBTROPICAL STORM REBEKAH FORMS OVER THE NORTH ATLANTIC... SUMMARY OF 500 PM AST...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...38.3N 40.7W ABOUT 745 MI...1195 KM W OF THE AZORES MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...E OR 80 DEGREES AT 13 MPH...20 KM/H MINIMUM CENTRAL PRESSURE...987 MB...29.15 INCHES WATCHES AND WARNINGS -------------------- Interests in the Azores should monitor the progress of Rebekah. There are no coastal watches or warnings in effect. DISCUSSION AND OUTLOOK ---------------------- At 500 PM AST (2100 UTC), the center of Subtropical Storm Rebekah was located near latitude 38.3 North, longitude 40.7 West. Rebekah is moving toward the east near 13 mph (20 km/h) and is forecast to turn toward the east-northeast tonight. A turn back toward the east and east-southeast is anticipated on Thursday. Maximum sustained winds are near 45 mph (75 km/h) with higher gusts. Little change in strength is anticipated for the next day or so. Gradual weakening is anticipated thereafter, and Rebekah is forecast to become a post-tropical cyclone on Friday. Winds of 40 mph extend outward up to 90 miles (150 km) from the center. The estimated minimum central pressure is 987 mb (29.15 inches). HAZARDS AFFECTING LAND ---------------------- Rebekah is forecast to be a post-tropical cyclone when it moves near the Azores in a day or so. Please see products issued by the Portuguese Institute for the Sea and Atmosphere (IPMA) for hazard information in the Azores related to Rebekah. NEXT ADVISORY ------------- Next complete advisory at 1100 PM AST. $$ Forecaster Zelinsky

You are correct. NHC will begin advisories on STS Rebekah at 5pm

Here are the others I found on the SPC archive for Tornado Watches covering any part of the LWX CWA from November: https://www.spc.noaa.gov/exper/archive/event.php?date=20101130 (November 30th, 2010 and went into Dec 1, 2010 as a Tornado Watch was issued for the DC metro at 3:45am on Dec 1st) https://www.spc.noaa.gov/exper/archive/event.php?date=20101116 (Nov 16 2010) https://www.spc.noaa.gov/exper/archive/event.php?date=20061116 (Nov 16, 2006 -- in addition 1630 Day 1 OTLK had the ultra rare hatched TOR for i95 corridor including DC/BALT metros... along with the mention for isolated but potentially strong tornadoes in the 1630 SPC disco) https://www.spc.noaa.gov/exper/archive/event.php?date=20021110 (Nov 11, 2002) Looks like only one for December: https://www.spc.noaa.gov/exper/archive/event.php?date=20001216 (Dec 16, 2000) The archive only goes back to 2000 though... so I am sure there were others before 2000 that had tornado watches for any portion of the LWX CWA

Yup... but I was including only LWX CWA counties... looks like in 2010 we had a tornado watch on back to back days in October (26th and 27th)

Here is one... October 27th, 2010 -- https://www.spc.noaa.gov/exper/archive/event.php?date=20101027

You know she will have pictures of one tomorrow on her table

I believe @Eskimo Joe already called for a tornado watch tomorrow Wonder when the last time we have had a tornado watch issued for the LWX CWA in October or later... will have to look in the SPC archives after work