Ellinwood Posted April 4, 2011 Share Posted April 4, 2011 Figured we should start a separate thread for this event. Included general obs. since most won't be severe east of the Apps., though stronger storms are still possible. If other posts like my discussion could be moved here, I'd appreciate it. From the SPC: ....OH VALLEY/CNTRL APPALACHIAN MTNS... AN AXIS OF LOW-LEVEL MOISTURE WILL MOVE EWD ACROSS THE OH VALLEY THIS MORNING AND INTO THE CNTRL APPALACHIAN MTNS THIS AFTERNOON AS A COLD FRONT ADVANCES QUICKLY EWD ACROSS THE REGION. THUNDERSTORMS SHOULD DEVELOP ALONG THE FRONT AS SFC HEATING TAKES PLACE THIS MORNING WITH A LINE OF STORMS ORGANIZING IN ERN IND AND CNTRL KY AROUND MIDDAY. STRONG DEEP LAYER SHEAR PROFILES WITH 40 TO 50 KT OF LOW-LEVEL FLOW SHOULD BE SUFFICIENT FOR A WIND DAMAGE THREAT WITH THE MORE INTENSE CELLS EMBEDDED IN THE LINE. IN ADDITION...THE STRONG DEEP LAYER SHEAR AND 500 MB TEMPS OF -14 TO 16C SHOULD BE SUFFICIENT FOR ISOLATED HAIL THREAT. THIS THREAT SHOULD MOVE EWD ACROSS OH...ERN KY INTO WV BY EARLY EVENING. Link to comment Share on other sites More sharing options...
North Balti Zen Posted April 4, 2011 Share Posted April 4, 2011 It's that sweet spot time of the year for my former home of 12 years, Memphis over to middle Tennessee. Numerous tornado warned storms I was through in those years, including (I think I've mentioned this) the one that hit Nashville in 1998 and damaged my house. That one I saw drop down over downtown Nashville as I was circling the city running an errand for work on the inner loop where I-40 comes through the city. My wife was on the interstate where the funnel first dropped down and saw a semi in front of her pushed sideways by the winds and almost off an elevated part of the roadway. She stopped the car and ran for a ditch. That was a helluva day. Link to comment Share on other sites More sharing options...
Ellinwood Posted April 4, 2011 Author Share Posted April 4, 2011 The RUC is coming in a lot more favorable for severe in the western parts of the region and for the possible target area of SW PA. 500-1000 J/kg CAPE with plenty of directional shear. Link to comment Share on other sites More sharing options...
Ellinwood Posted April 4, 2011 Author Share Posted April 4, 2011 13z SPC update looking much, MUCH better. SPC disc. looks fairly similar to what I wrote yesterday. They finally put SW PA in the 2% TOR risk area ...APPALACHIANS INTO PIEDMONT AND COASTAL PLAIN LATER TONIGHT INTO TUESDAY MORNING... STRONG AND DEEP ASCENT AHEAD OF DYNAMIC MIDLEVEL TROUGH IS EXPECTED TO MAINTAIN A BAND OF LOW-TOPPED TSTMS ALONG COLD FRONT PROGRESSING THROUGH THE REGION. WHILE AMBIENT AIR MASS WILL ONLY BE MARGINALLY UNSTABLE...BACKGROUND FORCING WILL BE FURTHER ENHANCED BY A WEAK FRONTAL WAVE WHICH IS FORECAST TO DEVELOP NNEWD IN THE LEE OF THE BLUE RIDGE AFTER 05/06Z. GIVEN THE RAPID STRENGTHENING OF THE DEEP SSWLY FLOW FIELD WHICH IS FORECAST E OF THE HIGHER TERRAIN...A RISK OF DAMAGING WINDS WILL EXIST WITH THE LOW-TOPPED CONVECTIVE BAND. Link to comment Share on other sites More sharing options...
CranberryWX Posted April 4, 2011 Share Posted April 4, 2011 It "feels" good today for storms....gusting SW wind bringing in warmth and moisture, temperature climbing nicely, but I've been disappointed by that feel before. Currently 72/53 with SW wind gusting to 18 mph. It will be Interesting to see how far north the Tornado Watch will be if they end up issuing one over here. It seems to be running along the OH river so far farther to the west. Link to comment Share on other sites More sharing options...
Kmlwx Posted April 4, 2011 Share Posted April 4, 2011 Early tomorrow morning (wee hours) - Link to comment Share on other sites More sharing options...
Ian Posted April 4, 2011 Share Posted April 4, 2011 10 a temps DCA 61 IAD 59 BWI 56 Link to comment Share on other sites More sharing options...
Ian Posted April 4, 2011 Share Posted April 4, 2011 Early tomorrow morning (wee hours) - biggest issue on models lately is we might get northern fringed, especially if the activity south is too strong. ill take what we can get at that time of day i guess. Link to comment Share on other sites More sharing options...
Avdave Posted April 4, 2011 Share Posted April 4, 2011 Early tomorrow morning (wee hours) - Good morning Loudoun Link to comment Share on other sites More sharing options...
Ian Posted April 4, 2011 Share Posted April 4, 2011 im wearing my first polo of the yr w00t Link to comment Share on other sites More sharing options...
Kmlwx Posted April 4, 2011 Share Posted April 4, 2011 09z tomorrow morning - Link to comment Share on other sites More sharing options...
Ian Posted April 4, 2011 Share Posted April 4, 2011 09z tomorrow morning - nice to look at but fairly meaningless in this situation. will never be realized with timing and low topped convection. Link to comment Share on other sites More sharing options...
Kmlwx Posted April 4, 2011 Share Posted April 4, 2011 nice to look at but fairly meaningless in this situation. will never be realized with timing and low topped convection. Yeah meh. At least it has improved over prior runs which I guess is a somewhat good sign that we will at least get some rumblers. Link to comment Share on other sites More sharing options...
CranberryWX Posted April 4, 2011 Share Posted April 4, 2011 Wind gust up to 24 in on my semi sheltered annemometer. It sounds higher through the tree tops...loose stuff is starting to fly/move around. It pushed my chairs across the deck. CRW is starting to ratchet it up a little bit: 10:32 Update : STILL A VOLATILE SITUATION...THAT NEEDS TO BE STRESSED. AT 14Z...THINKING THE MODELS ARE A BIT SLOW BRINGING IN THE INITIAL CONVECTION THIS AFTERNOON. WITH 60 KNOT STEERING CURRENT...THE CONVECTION NEAR EVANSVILLE...WILL LIKELY ARRIVE IN OUR CWA BY 18Z OR SO. SO WILL INCREASE AFTERNOON POPS IN THE WEST A BIT FASTER. STILL EXPECT A CONVECTIVE WATCH...BUT...DO NOT UNDERESTIMATE THE RAW SYNOPTIC FLOW. GUSTS IN THE WARM SECTOR CAN EASILY REACH 40 MPH. HAVE THE NORTHERN CONVECTION AT 14Z BRUSHING SOUTHEAST OHIO MAINLY ATHENS ON NORTH DURING THE LATE MORNING MIDDAY PERIOD...BUT DO NOT EXPECT CONVECTIVE SEVERE IN THAT. ONCE THE CONVECTION GETS GOING...OUR SYNOPTIC WINDS AT THE SURFACE MAY EVEN DECREASE LATE THIS AFTERNOON AND EARLY THIS EVENING AS SURFACE TEMPERATURES DROP IN THE RAIN...BUT THEN THERE COULD BE SHORT FUSE CONVECTIVE WARNINGS ONGOING. STILL HAVE SYNOPTIC SURFACE WINDS INCREASING AGAIN WITH COLD FRONTAL PASSAGE PLUS FOR 1 TO 4 HOURS IN ITS WAKE. AND IF THERE IS NOT ENOUGH HAPPENING...WE CAN NOT FORGET ABOUT THE WATER. OF COURSE...STREET FLOODING WITH ANY HEAVY RAIN. WOULD TAKE A LONG TRAINING OF SHOWERS...BUT IF RAIN AMOUNTS OVER 1.5 INCHES START INCREASING...SMALL STREAM FLOODING MAY BE AN ISSUE. LUCKILY...OUR WESTERN LOWLAND COUNTIES ALONG THE OHIO RIVER ARE INITIALLY DRIER THAN OUR MOUNTAINS...SOME OF WHICH ARE STILL MELTING THEIR SNOW. Link to comment Share on other sites More sharing options...
Kmlwx Posted April 4, 2011 Share Posted April 4, 2011 06z run of one of the LWX local models for 10z tomorrow - Link to comment Share on other sites More sharing options...
yoda Posted April 4, 2011 Share Posted April 4, 2011 AREA FORECAST DISCUSSIONNATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1059 AM EDT MON APR 4 2011 .NEAR TERM /THROUGH TONIGHT/... -- Changed Discussion --WARM FRONT WILL CONTINUE TO MOVE NORTH OF THE CWA THIS MRNG. BASED ON 12Z IAD RAOB...SFC HEATING WILL QUICKLY MIX DOWN THE WARM AIR /15C AT H8/ DURING THE MRNG AND AFTN. THIN MID AND HI CLOUDS AFFECTING THE AREA TDA SHOULD NOT HAVE A HUGE IMPACT ON HEATING...ESPECIALLY ACROSS CENTRAL VA...WHERE CLOUDS WILL BE THINNEST. HIGHS WILL NEAR 80F ACROSS THE ENTIRE REGION...WITH THE EXCEPTION OF MU70S NEAR THE MASON-DIXON LINE. ISSUED A WIND ADVISORY FOR THE HIGHER ELEVATIONS /MAINLY ABOVE 2 KFT/ OF THE POTOMAC HIGHLANDS AND CENTRAL FOOTHILLS FOR TDA AND TNGT. STRONG BOUNDARY LAYER LAPSE RATES OWING TO SFC HEATING WILL HELP MIX DOWN 50 MPH WINDS DOWN TO THE RIDGE TOPS. WILL NEED TO MONITOR THE POTENTIAL FOR THE WIND ADVISORY TO BE EXPANDED FURTHER EAST...ALTHOUGH THE LLVL JET MAX DOESNT MOVE IN UNTIL AFTER SUNSET WHEN BOUNDARY LAYER LAPSE RATES WILL NOT BE SUPPORTIVE FOR DEEP MIXING OF THE 50 MPH WIND GUSTS ACROSS THE COASTAL PLAIN. WITH SYNOPTIC FORCING ASSOCIATED WITH THE AMPLIFYING UPPER TROUGH/SFC COLD FRONT REMAINING TO THE WEST AND STRONG CAPPING INVERSIONS BETWEEN THE H9-H7 LAYER...MOST OF THE CWA SHOULD REMAIN DRY TDA. HOWEVER...ONGOING CONVECTION OVER THE OH VLY MAY CLIP THE POTOMAC HIGHLANDS/WRN MD DURING THE LATE AFTN/EVE AS A PRE-FRONTAL SFC TROUGH APPROACHES THE NWRN CWA. LAST FEW RUNS OF THE 4 KM HRRR WRF SUPPORT THIS IDEA. THIS ACTIVITY ACROSS THE HIGHLANDS WILL HAVE THE POTENTIAL TO BECOME SEVERE AS IT TAPS INTO HIGHER SFC INSTABILITY FROM THE AFTN HEATING. 06Z NAM PROFILES SHOW INCREASING SHEAR PROFILES AND 400-600 J/KG SBCAPE ONCE THE CAPPING INVERSION BREAKS. CD FNT PRSNTLY OVR IL WL BE MOVG INTO THE HIGHLANDS ARND 06Z AND ENTERING THE CHES BAY ARND 12Z. THIS IS NOT A FAVORABLE TIME FOR CNVCTN...BUT OBVIOUSLY GIVEN THE FACT THAT THE SFC TEMP WL APRCH 80 DURG THE DAY THERE WL BE SOME CAPE AVBL TNGT...AND WIND FIELD IS CERTAINLY IMPRESSIVE W/ THE "INVERTED U" HODOGRAPH THAT ALWAYS GETS MY ATTENTION. BULK OF THE CONVECTIVE ACTIVITY ASSOCIATED WITH THE COLD FRONT IS EXPECTED OVNGT. SPC DAY 1 OUTLOOK HAS BEEN UPDATED TO INCLUDE THE CWA FOR THE NIGHTTIME CONVECTION. THE MAIN THREAT WILL BE DAMAGING WINDS WITH SECONDARY THREATS BEING ISO HAIL/TORNADOES ALONG AND WEST OF THE BLUE RIDGE. HEAVY RAINFALL/FLASH FLOODING THREAT WILL BE LIMITED BY FAST EASTWARD PROGRESSION OF THE COLD FRONT. LOW TEMPS RANGING FM THE U50S E OF I-95 TO THE MU30S IN THE HIGHLANDS. GIVEN THOSE TEMPS PCPN MAY BE TURNING TO SN AT THE HIGHER ELEVS LATE.-- End Changed Discussion -- Link to comment Share on other sites More sharing options...
Kmlwx Posted April 4, 2011 Share Posted April 4, 2011 12z run of the LWX ARW model - for 10z tomorrow morning Link to comment Share on other sites More sharing options...
yoda Posted April 4, 2011 Share Posted April 4, 2011 12z run of the LWX ARW model - for 10z tomorrow morning That looks pretty good... Link to comment Share on other sites More sharing options...
Ian Posted April 4, 2011 Share Posted April 4, 2011 1p DCA 73 IAD/BWI 68 Link to comment Share on other sites More sharing options...
yoda Posted April 4, 2011 Share Posted April 4, 2011 Nothing really new from the 1630 SPC OTLK Link to comment Share on other sites More sharing options...
pazzo83 Posted April 4, 2011 Share Posted April 4, 2011 Torch down in the Shen Valley, SHD (Staunton) is at 77. Even higher on the other side of the blue ridge, CHO at 79. Link to comment Share on other sites More sharing options...
mappy Posted April 4, 2011 Share Posted April 4, 2011 1p DCA 73 IAD/BWI 68 74 at BWI at 1pm 75 at the Inner Harbor Link to comment Share on other sites More sharing options...
Ian Posted April 4, 2011 Share Posted April 4, 2011 Nothing really new from the 1630 SPC OTLK im voting meh, but hopeful. qlcs-like morning early-season ftl. hopefully we get some lightning. Link to comment Share on other sites More sharing options...
CranberryWX Posted April 4, 2011 Share Posted April 4, 2011 Currently 79/58. It's hot out and windy. Car therm was over 80 while out to lunch. Dark clouds to the NW. Tornado Watch moved a little closer. Link to comment Share on other sites More sharing options...
Riptide Posted April 4, 2011 Share Posted April 4, 2011 It's in the 70's already, even out here near the bay. Rather impressive even though there isn't much CAPE(Instability) around anywhere. Link to comment Share on other sites More sharing options...
Kmlwx Posted April 4, 2011 Share Posted April 4, 2011 It's in the 70's already, even out here near the bay. Rather impressive even though there isn't much CAPE(Instability) around anywhere. Mid level lapse rates are pretty impressive though, at least at the moment Link to comment Share on other sites More sharing options...
yoda Posted April 4, 2011 Share Posted April 4, 2011 Mid level lapse rates are pretty impressive though, at least at the moment Does that deal with hail or winds? Link to comment Share on other sites More sharing options...
Kmlwx Posted April 4, 2011 Share Posted April 4, 2011 Does that deal with hail or winds? No clue - I just know that in most of our severe events Low level lapse rates are steep while mid level lapse rates usually don't look this steep. Link to comment Share on other sites More sharing options...
mappy Posted April 4, 2011 Share Posted April 4, 2011 2pm 79 at BWI 77 at the Inner Harbor Mark - I told you it would be upper 70s today!!! Link to comment Share on other sites More sharing options...
Kmlwx Posted April 4, 2011 Share Posted April 4, 2011 2pm 79 at BWI 77 at the Inner Harbor Mark - I told you it would be upper 70s today!!! With still heating to go! Link to comment Share on other sites More sharing options...
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