Amped Posted September 18, 2012 Share Posted September 18, 2012 The LCL at Lancaster tomorrow at 2PM according to the NAM will be at 968mb, also at that time, I will be standing on a 950 ASL foot hill. In that case it will be a little foggy. Link to comment Share on other sites More sharing options...
wxmeddler Posted September 18, 2012 Share Posted September 18, 2012 I still have somewhat mixed feelings about this event for some reason. I think I'm hoping that the tornado potential overperforms as I think the squall has potential to underperform. Wonder if we'll have two distinct batches--a potential group of rotating somethings 'early' (mid-afternoonish) then a bit of a lull before the frontal band. That's my bet. Isolated cells to start, but instead of one long frontal squall, we have multiple line segments staggered (like slanted stairs). Link to comment Share on other sites More sharing options...
Ian Posted September 18, 2012 Share Posted September 18, 2012 That's my bet. Isolated cells to start, but instead of one long frontal squall, we have multiple line segments staggered (like slanted stairs). Over under on noon for first tornado warning from LWX? Link to comment Share on other sites More sharing options...
yoda Posted September 18, 2012 Share Posted September 18, 2012 Over under on noon for first tornado warning from LWX? Under... barely... 1130 Link to comment Share on other sites More sharing options...
wxmeddler Posted September 18, 2012 Share Posted September 18, 2012 Over under on noon for first tornado warning from LWX? After, but one might sneak in down towards the far SW corner near Nelson county. My guess for the first possible tornado warning in the metro region (WTOP coverage area let's say) would be around 2:30 give or take a half an hour. Link to comment Share on other sites More sharing options...
yoda Posted September 18, 2012 Share Posted September 18, 2012 910 update AFD from LWX .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... ATMOSPHERE WILL CONTINUE TO MOISTEN INTO TUESDAY MORNING AS A STRONG LOW LEVEL SOUTHERLY JET DEVELOPS /GREATER THAN 50 KT AT 850 MB BY AFTERNOON/. THIS COULD SEND PRECIPITABLE WATER VALUES UP TO 2 INCHES EAST OF THE BLUE RIDGE. WITH THE HIGH MOISTURE CONTENT AND LINGERING WARM ADVECTION...THERE WILL BE SOME SHOWERS TO THE START THE DAY BUT AS DYNAMICS/SHEAR INCREASE AND A COLD FRONT APPROACHES FROM THE WEST...ORGANIZED CONVECTION WILL BECOME LIKELY DURING THE LATE MORNING AND AFTERNOON. SOME HIGH RESOLUTION MODELS SUGGEST ONE OR MORE LINES OF THUNDERSTORMS DEVELOPING. WHILE INSTABILITY IS FORECAST TO BE WEAK...HIGH SHEAR WILL LIKELY BE ABLE TO OVERCOME THIS LIMITATION AND LEAD TO SHOWERS AND THUNDERSTORMS THAT WILL BE CAPABLE OF PRODUCING DAMAGING WIND GUSTS. IN ADDITION...ISOLATED TORNADOES WILL BE POSSIBLE WITHIN ANY LINEAR CONVECTIVE STRUCTURE AND ALSO ANY SUPERCELLS THAT COULD FORM AHEAD OF THE LINE. THERE WILL ALSO BE A RISK OF LOCALIZED FLASH FLOODING PRIMARILY WITHIN THE URBAN CORRIDOR WHERE FLASH FLOOD GUIDANCE IS LOWEST. AT THIS TIME...NOON TO 7 PM APPEARS TO BE THE MOST LIKELY TIME FOR SEVERE WEATHER ACROSS THE CWA ON TUESDAY. Link to comment Share on other sites More sharing options...
yoda Posted September 18, 2012 Share Posted September 18, 2012 English translation please? The NAM's double structured LLJ, enhanced surface convergence and primer vorticity ahead of the main "show" would possibly be enough to overcome any shallow inversion/weak instability. It is also indicative of a period of enhanced ageostrophic lift and possibly signals enhancement from the mid-upper levels aiding in this low level forcing. Could prove to be a focal point for supercells. Very evident over DC and MD at 18z. Link to comment Share on other sites More sharing options...
TalcottWx Posted September 18, 2012 Share Posted September 18, 2012 English translation please? Vort max and llj will combine to overcome a lack of instability and will be enhanced by aid from mid level forcing. Basically strong lift aiding the strong shear will help any storms organize to their max potential without the need of high instability values, even if there is an inversion. Link to comment Share on other sites More sharing options...
yoda Posted September 18, 2012 Share Posted September 18, 2012 Well this is... interesting Link to comment Share on other sites More sharing options...
yoda Posted September 18, 2012 Share Posted September 18, 2012 DCA at 18z per 00z GFS Link to comment Share on other sites More sharing options...
andyhb Posted September 18, 2012 Share Posted September 18, 2012 RAP has seriously nasty LL helicity throughout the region tomorrow. Looks like it wants to throw further south into the party as well. Link to comment Share on other sites More sharing options...
Kmlwx Posted September 18, 2012 Share Posted September 18, 2012 Whoa...CAPE upped. Link to comment Share on other sites More sharing options...
Yeoman Posted September 18, 2012 Share Posted September 18, 2012 Well this is... interesting WOW!!!!!!!!!!!!!!!!!!!!111!11! Link to comment Share on other sites More sharing options...
yoda Posted September 18, 2012 Share Posted September 18, 2012 WOW!!!!!!!!!!!!!!!!!!!!111!11! I know!! Its like, so impressive, like, there could be, like, a tornado or something Link to comment Share on other sites More sharing options...
Amped Posted September 18, 2012 Share Posted September 18, 2012 BRN shear is kind of low. I didn't know what it was until I looked it up either. Link to comment Share on other sites More sharing options...
TalcottWx Posted September 18, 2012 Share Posted September 18, 2012 That wind profile is beautiful Link to comment Share on other sites More sharing options...
EasternUSWX Posted September 18, 2012 Share Posted September 18, 2012 I know!! Its like, so impressive, like, there could be, like, a tornado or something EF2 Tornado Hodo. Link to comment Share on other sites More sharing options...
andyhb Posted September 18, 2012 Share Posted September 18, 2012 BRN shear is kind of low. I didn't know what it was until I looked it up either. Link to comment Share on other sites More sharing options...
Yeoman Posted September 18, 2012 Share Posted September 18, 2012 I know!! Its like, so impressive, like, there could be, like, a tornado or something Anyone check the GLAMM? Link to comment Share on other sites More sharing options...
Jon Posted September 18, 2012 Share Posted September 18, 2012 RAP has seriously nasty LL helicity throughout the region tomorrow. Looks like it wants to throw further south into the party as well. That's what I'm talking about! Link to comment Share on other sites More sharing options...
TalcottWx Posted September 18, 2012 Share Posted September 18, 2012 EF2 Tornado Hodo. ef5 Link to comment Share on other sites More sharing options...
EasternUSWX Posted September 18, 2012 Share Posted September 18, 2012 ef5 October 18, 2007: Kalkaska MI EF2 tornado 00Z APX RAOB minisupercell, changed mean wind depth from 6 to 4 km 0-1 km SRH: 276 m2 s-2 0-3 km SRH: 289 m2 s-2 0-1 km bulk shear: 43 kt 0-6 km bulk shear: 94 kt 5 km SR wind: 39 kt 7-10 km SRW: 41 kt (N/A) storm motion: 211 @ 44 kt Link to comment Share on other sites More sharing options...
EasternUSWX Posted September 18, 2012 Share Posted September 18, 2012 Helicity is pretty crazy. Link to comment Share on other sites More sharing options...
TalcottWx Posted September 18, 2012 Share Posted September 18, 2012 October 18, 2007: Kalkaska MI EF2 tornado 00Z APX RAOB minisupercell, changed mean wind depth from 6 to 4 km 0-1 km SRH: 276 m2 s-2 0-3 km SRH: 289 m2 s-2 0-1 km bulk shear: 43 kt 0-6 km bulk shear: 94 kt 5 km SR wind: 39 kt 7-10 km SRW: 41 kt (N/A) storm motion: 211 @ 44 kt Was kiddin' Link to comment Share on other sites More sharing options...
PhineasC Posted September 18, 2012 Share Posted September 18, 2012 As usual, the amount of hype is inversely proportional to the amount of severe weather I experience so I expect just some scattered showers at best. Link to comment Share on other sites More sharing options...
WEATHER53 Posted September 18, 2012 Share Posted September 18, 2012 Warm front going to cause more problems than cold front. Link to comment Share on other sites More sharing options...
EasternUSWX Posted September 18, 2012 Share Posted September 18, 2012 RPM FTW Click on regional http://www.chicagoweathercenter.com/maps/rpm/ Link to comment Share on other sites More sharing options...
andyhb Posted September 18, 2012 Share Posted September 18, 2012 Alright then, the 04z RAP is progging 450-700 m2/s2 of 0-3 km SRH in the DCA-Philly corridor from around 18-21z along with 1000+ J/kg CAPE... Between Baltimore and Annapolis, 19z: Link to comment Share on other sites More sharing options...
wxmeddler Posted September 18, 2012 Share Posted September 18, 2012 NHC has already issued their 2PM TWO, Still waiting on SPC Lucky I have homework. Link to comment Share on other sites More sharing options...
andyhb Posted September 18, 2012 Share Posted September 18, 2012 Big time 10% tor on the new D1, still slight. ..ERN U.S. ALONG AND E OF THE APPALACHIANS A VERY COMPLEX SCENARIO IS UNFOLDING...WITH WIDESPREAD PRECIPITATION EXPECTED TO BE ONGOING AT THE START OF THE PERIOD WITHIN A BEND FROM NEW YORK SWWD INTO THE CENTRAL GULF COAST REGION -- LARGELY ASSOCIATED WITH THE WEAKENING/SRN UPPER SYSTEM. THIS WIDESPREAD CLOUDINESS/PRECIPITATION WILL RESULT IN WEAK LAPSE RATES...AND LITTLE POTENTIAL FOR APPRECIABLE AIRMASS DESTABILIZATION ACROSS A LARGE PORTION OF THE RISK AREA. HOWEVER...AS THE MAIN UPPER TROUGH EXPANDS/SHIFTS EWD WITH TIME...STRONG FLOW ALOFT E OF THE TROUGH WILL SPREAD ACROSS THE WARM SECTOR...RESULTING IN SHEAR PROFILES HIGHLY SUPPORTIVE OF ROTATING STORMS. CLEARLY...THE LACK OF BUOYANCY ACROSS MANY AREAS WILL ACT TO LIMIT SEVERE POTENTIAL...BUT THE DEGREE OF VEERING/SHEAR ANTICIPATED WARRANTS LOW SEVERE/TORNADO PROBABILITY ACROSS THE MAJORITY OF THE U.S. E OF THE APPALACHIAN CREST. ATTM...IT APPEARS THAT THE GREATEST SEVERE THREAT MAY EVOLVE ACROSS PARTS OF SERN NY/ERN PA/MD/VA AND INTO SRN NEW ENGLAND/NJ/DE. THIS PORTION OF THE REGION MAY REMAIN E OF THE MORE EXPANSIVE ZONE OF CLOUDS/PRECIPITATION INTO THE AFTERNOON -- POSSIBLY ALLOWING POCKETS OF WEAK HEATING/DESTABILIZATION. THUS -- WITH SOME POSSIBILITY OF GREATER THERMODYNAMIC SUPPORT FOR MORE VIGOROUS CONVECTION IN THIS AREA...POTENTIAL FOR UPDRAFTS TO INTERACT WITH A VERY FAVORABLE BACKGROUND KINEMATIC FIELD SUGGESTS POTENTIAL FOR MORE WIDESPREAD DAMAGING WINDS AND A FEW TORNADOES. GIVEN UNCERTAINTY...AND A GENERAL LACK OF CAPE ANTICIPATED ATTM...THIS SCENARIO DOES NOT APPEAR TO WARRANT MDT RISK UPGRADE ATTM. STILL...SMALL ZONES OF FAIRLY INTENSE/ROTATING CONVECTION CAPABLE OF PRODUCING LOCALLY DAMAGING SEVERE WEATHER APPEAR LIKELY. SEVERE THREAT SHOULD CONTINUE INTO THE EVENING/OVERNIGHT HOURS AS STRONG SHEAR PERSISTS -- PARTICULARLY ACROSS THE NRN HALF OF THE RISK AREA...ENDING FROM W TO E AS THE FRONT GRADUALLY APPROACHES/REACHES THE COAST. Link to comment Share on other sites More sharing options...
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