yoda Posted April 12, 2020 Share Posted April 12, 2020 1 Link to comment Share on other sites More sharing options...
AmericanWxFreak Posted April 12, 2020 Share Posted April 12, 2020 Took a huge chunk of the slight risk area away - must not be seeing things like we are... Link to comment Share on other sites More sharing options...
southmdwatcher Posted April 12, 2020 Share Posted April 12, 2020 That will be fluid tomorrow, I expect the northern extent to change again and some portion of the Enhanced area may go to Moderate for tornadoes. Link to comment Share on other sites More sharing options...
southmdwatcher Posted April 12, 2020 Share Posted April 12, 2020 https://weather.cod.edu/text/ DAY 2 CONVECTIVE OUTLOOK NWS STORM PREDICTION CENTER NORMAN OK 1221 AM CDT SUN APR 12 2020 VALID 131200Z - 141200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF EASTERN GEORGIA...THE CENTRAL AND EASTERN CAROLINAS AND VIRGINIA... ..SUMMARY SEVERE THUNDERSTORMS WITH TORNADOES, DAMAGING WIND GUSTS AND HAIL WILL BE LIKELY ACROSS PARTS OF THE ATLANTIC COASTAL PLAINS INTO THE CENTRAL APPALACHIANS ON MONDAY. ..ATLANTIC COASTAL PLAINS/CENTRAL APPALACHIANS A POTENT SHORTWAVE TROUGH WILL MOVE QUICKLY NORTHEASTWARD ACROSS THE OHIO AND TENNESSEE VALLEYS TONIGHT. THE TROUGH SHOULD BE POSITIONED OVER THE CENTRAL APPALACHIANS AT THE START OF THE PERIOD. AT THAT TIME, A 70 TO 80 KT LOW-LEVEL JET WILL BE LOCATED ACROSS THE CAROLINAS AND VIRGINIA WITH AN AXIS OF MODERATE INSTABILITY CO-LOCATED WITH THE JET. A BAND OF CONVECTION, POTENTIALLY SEVERE, IS FORECAST TO BE IN NORTHEAST GEORGIA, THE WESTERN CAROLINAS AND WESTERN VIRGINIA AT 12Z. OTHER STRONG THUNDERSTORMS MAY BE ONGOING IN THE UPPER OHIO VALLEY. AN 80 TO 100 KT MID-LEVEL JET ORIENTED ALONG THE WESTERN EDGE OF THE LOW-LEVEL JET WILL CREATE VERY STRONG DEEP-LAYER SHEAR FAVORABLE FOR SEVERE THUNDERSTORMS. THIS BAND OF CONVECTION IS FORECAST TO MOVE QUICKLY EASTWARD ACROSS THE ATLANTIC COASTAL PLAINS DURING THE MORNING AND EARLY AFTERNOON. THE MAIN QUESTION WITH THIS OUTLOOK IS CONVECTIVE MODE. THERE ARE TWO POSSIBILITIES. THE FIRST IS THAT THE BAND OF THUNDERSTORMS WILL HAVE DISCRETE ELEMENTS AND GAPS THAT WILL BE FAVORABLE FOR SUPERCELLS AND TORNADOES. FORECAST SOUNDINGS AT 15Z FROM SOUTHERN VIRGINIA SOUTHWARD INTO NORTHERN SOUTH CAROLINA SHOW LOOPED HODOGRAPHS WITH 0-3 KM STORM RELATIVE HELICITIES IN THE EXTREME CATOGORY, GENERALLY NEAR OR ABOVE 600 M2/S2. THIS WOULD SUPPORT A THREAT FOR STRONG TORNADOES ASSOCIATED WITH THE MORE DOMINANT SUPERCELLS. A WIND DAMAGE AND HAIL THREAT WOULD BE LIKELY WITH SUPERCELLS AND WITH THE MORE ORGANIZED LINE SEGMENTS. THE SECOND SCENARIO WOULD BE THAT A SQUALL-LINE IS ONGOING AT 12Z FROM EASTERN GEORGIA NORTHWARD INTO THE WESTERN CAROLINAS AND VIRGINIA. IN THAT CASE, WIDESPREAD WIND DAMAGE WOULD BE LIKELY. A QLCS TORNADO THREAT WOULD EXIST WITH THE STRONGER BOWING LINE SEGMENTS. HAIL WOULD ALSO BE POSSIBLE WITH THE MORE INTENSE PARTS OF THE LINE. AT THIS TIME, THE OUTLOOK REFLECTS THE FIRST SCENARIO IN WHICH MORE DISCRETE CELLS ARE PRESENT ACROSS THE WARM SECTOR AT 12Z. IN THIS CASE, A CLUSTER OUTBREAK OF TORNADOES WOULD BE POSSIBLE AND A STRONG LONG-TRACK TORNADO OR TWO CAN NOT BE RULED OUT. ..BROYLES.. 04/12/2020 2 Link to comment Share on other sites More sharing options...
Kmlwx Posted April 12, 2020 Author Share Posted April 12, 2020 They amended the D2. Weird Link to comment Share on other sites More sharing options...
Kmlwx Posted April 12, 2020 Author Share Posted April 12, 2020 LWX in their AM discussion was indicating only wind advisories for most of the area. HWW confined to ridge tops. NAM (06z) still has crazy winds at the 850 and 925 levels. NAM nest has surface wind gusts to 65mph almost area wide. Link to comment Share on other sites More sharing options...
Kmlwx Posted April 12, 2020 Author Share Posted April 12, 2020 0z HREF has ensemble mean 850mb winds of 75 knots around the area on Mon. Link to comment Share on other sites More sharing options...
George BM Posted April 12, 2020 Share Posted April 12, 2020 2 minutes ago, Kmlwx said: 0z HREF has ensemble mean 850mb winds of 75 knots around the area on Mon. 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. Link to comment Share on other sites More sharing options...
arlwx Posted April 12, 2020 Share Posted April 12, 2020 LWX is suggesting some may need a run to the battery store... (snip) The dry slot will work its way into the area later Monday morning and the cold front will pass through the area Monday afternoon into Monday evening. On the edge of the dry slot and ahead of the cold front is where stronger thunderstorms are most likely Monday morning and afternoon. Long and curved hodographs are seen in forecast soundings to the very strong winds aloft. The very strong wind flow, along with strong warm and moist advection, combined with forcing from the front and somewhat of an enhancement in instability on the edge of the dry slot, suggests that a broken line of showers and thunderstorms will develop Monday morning and progress east and northeast into Monday afternoon. Embedded supercells are possible withing the line along with a possible QLCS feature. Therefore, damaging winds are a concern with convection Monday along with an increased threat for a tornado and large hail. Localized flash flooding cannot be ruled out, but the storms should have enough motion to keep that threat localized. Another threat for overnight and Monday will be gradient wind outside of heavier showers and thunderstorms. For the overnight, a very strong low-level jet will develop but with warm advection and showers overhead it will be tough to mix down. It will still turn out quite breezy with frequent gusts around 20-35 mph for most areas. There could be gusts 40-55 knots along the highest ridge tops above 3000 feet, but did not include these in a wind headline at this time since it will be very isolated. However, with strong warm advection Monday morning, the mixing layer will begin to increase, causing winds to increase. For Monday afternoon, there will be dry advection and weak cold advection behind the dry slot. This will enhance the mixing layer even more. As of now, it appears that wind gusts will be around 45-55 mph for most areas late Monday morning through most of Monday afternoon. A Wind Advisory will likely be needed. Did issue a High Wind Watch for the ridges of the Allegheny and Potomac Highlands as well as the Blue Ridge Mountains where stronger winds are likely over the higher elevations. Also included central Mineral, Grant, and Allegany Counties due to a downsloping flow off the mountains that may enhance winds in those areas. Gusts around 60 mph are possible. One thing to note is that there may be numerous fallen trees if these strong winds do occur, and that is because the ground will be much more saturated due to recent rainfall, compared to when the ground is mainly dry during these types of gradient wind events. (snip) Link to comment Share on other sites More sharing options...
AmericanWxFreak Posted April 12, 2020 Share Posted April 12, 2020 So no slight and no HWW? This sure has lamed out... We always find away for things to not be exciting. 1 Link to comment Share on other sites More sharing options...
Kmlwx Posted April 12, 2020 Author Share Posted April 12, 2020 2 minutes ago, AmericanWxFreak said: So no slight and no HWW? This sure has lamed out... We always find away for things to not be exciting. Huh? Entire area is under a slight risk with ENH not far away. Outlook was amended about 1 hour after issuance. 1 Link to comment Share on other sites More sharing options...
Kmlwx Posted April 12, 2020 Author Share Posted April 12, 2020 WRF-NSSL run looks very robust for our area. Link below - several models on this page, in fact. https://cams.nssl.noaa.gov/?model=wrf_nssl_3km&rd=20200412&rt=0000&product=sbcape§or=spc_ma&postage_stamp=false Link to comment Share on other sites More sharing options...
AmericanWxFreak Posted April 12, 2020 Share Posted April 12, 2020 11 minutes ago, Kmlwx said: Huh? Entire area is under a slight risk with ENH not far away. Outlook was amended about 1 hour after issuance. Oh wow, I went to bed RIGHT after the initial one and never looked again. Thanks! Link to comment Share on other sites More sharing options...
osfan24 Posted April 12, 2020 Share Posted April 12, 2020 5 hours ago, AmericanWxFreak said: Took a huge chunk of the slight risk area away - must not be seeing things like we are... FWIW, DT posted an update last night and said he doesn't see any significant severe weather for Central MD area. Link to comment Share on other sites More sharing options...
Eskimo Joe Posted April 12, 2020 Share Posted April 12, 2020 SWODY2 has been updated. IMO, this is fine. Link to comment Share on other sites More sharing options...
Kmlwx Posted April 12, 2020 Author Share Posted April 12, 2020 Have to say - the big gap in the high wind watch products from WFOs to the west of LWX and WFOs east of LWX doesn't look great. Don't see a ton of harm going with a WATCH and ultimately going with an advisory if the higher wind progs don't end up verifying. But the whole purpose of a watch is for this reason. Could easily see gusts to the 58mph criteria. I wonder if their plan is to go with an advisory and then cover any HWW criteria winds with SVRs 1 Link to comment Share on other sites More sharing options...
CAPE Posted April 12, 2020 Share Posted April 12, 2020 18 minutes ago, Kmlwx said: Have to say - the big gap in the high wind watch products from WFOs to the west of LWX and WFOs east of LWX doesn't look great. Don't see a ton of harm going with a WATCH and ultimately going with an advisory if the higher wind progs don't end up verifying. But the whole purpose of a watch is for this reason. Could easily see gusts to the 58mph criteria. I wonder if their plan is to go with an advisory and then cover any HWW criteria winds with SVRs I have a feeling the watch here will end up being an advisory, with a warning along the coasts of DE and NJ, and also the western highlands. 1 Link to comment Share on other sites More sharing options...
Stormfly Posted April 12, 2020 Share Posted April 12, 2020 If this verifies then there's going to be a LOT of tree/power pole damage! 1 Link to comment Share on other sites More sharing options...
Buddy1987 Posted April 12, 2020 Share Posted April 12, 2020 The verbiage on the Day 2 synopsis is concerning considering they go with possible strong tornadoes and an outbreak and mention southern va and areas around. Not sure I’ve ever seen that in the 10 years I’ve lived here myself except maybe one time but the ingredients never came together. Link to comment Share on other sites More sharing options...
Kmlwx Posted April 12, 2020 Author Share Posted April 12, 2020 Not sure how useful the RAP is anymore - but at range it has 80-90kts at the 850mb level at 15z tomorrow. Link to comment Share on other sites More sharing options...
Kmlwx Posted April 12, 2020 Author Share Posted April 12, 2020 LOL at the RAP on the 09z run Link to comment Share on other sites More sharing options...
George BM Posted April 12, 2020 Share Posted April 12, 2020 1 minute ago, Kmlwx said: Not sure how useful the RAP is anymore - but at range it has 80-90kts at the 850mb level at 15z tomorrow. 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. Link to comment Share on other sites More sharing options...
Kmlwx Posted April 12, 2020 Author Share Posted April 12, 2020 If you took that RAP run at face value - it would seem to indicate we have just as much potential as some places in the Carolinas. I don't buy it. But the models continue to spit out some very healthy solutions for our area. Link to comment Share on other sites More sharing options...
George BM Posted April 12, 2020 Share Posted April 12, 2020 Also RAP'd. Link to comment Share on other sites More sharing options...
Kmlwx Posted April 12, 2020 Author Share Posted April 12, 2020 Long range 12z HRRR also going kinda bonkers... Link to comment Share on other sites More sharing options...
southmdwatcher Posted April 12, 2020 Share Posted April 12, 2020 There is a meso low in eastern Texas moving east northeastward with the MCS. That will probably be a large factor in what we see tomorrow. Link to comment Share on other sites More sharing options...
Kmlwx Posted April 12, 2020 Author Share Posted April 12, 2020 Going to be interesting to see what the 3km NAM spits out. GFS will bring us back to reality as usual. But interesting to see the models maxing out with time... Link to comment Share on other sites More sharing options...
Eskimo Joe Posted April 12, 2020 Share Posted April 12, 2020 00z runs are the go/no go run for me. Big question for potential bust on the low end in these parts is whether the lack of aircraft sampling leads to any NWP errors. Link to comment Share on other sites More sharing options...
Kmlwx Posted April 12, 2020 Author Share Posted April 12, 2020 12z NAM (12km) has less CAPE into Southern PA. But still looks excellent for the DC area. Link to comment Share on other sites More sharing options...
Eskimo Joe Posted April 12, 2020 Share Posted April 12, 2020 So uh, on the SWODY2 the 5% tor is into PA and the 10% [hatched] tor is just south of DC to SBY. 2 Link to comment Share on other sites More sharing options...
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