NA - Moderate Risk (Lower MS Valley Region) 22-11-2011
Posted 22 November 2011 - 13:22
SPC AC 221249
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0649 AM CST TUE NOV 22 2011
VALID 221300Z - 231200Z
...THERE IS A SLGT RISK OF SVR TSTMS THROUGH TONIGHT FOR THE LOWER
MS/TN/OH VALLEY REGION...
...LOWER MS/TN/OH VALLEY REGION THROUGH EARLY TONIGHT...
A POSITIVELY-TILTED MIDLEVEL TROUGH FROM N TX TO MO WILL PROGRESS
EWD TO THE OH/TN VALLEYS THIS EVENING AND THE APPALACHIANS BY
WEDNESDAY MORNING. AN ASSOCIATED SURFACE CYCLONE NEAR THE MO
BOOTHEEL WILL DEVELOP NEWD IN ADVANCE OF THE MIDLEVEL TROUGH...ALONG
A PRE-EXISTING FRONT ALIGNED NEAR THE OH RIVER. A TRAILING COLD
FRONT WILL MOVE SEWD ACROSS TX AND THE LOWER MS/TN VALLEYS THROUGH
THE STRONGER FORCING FOR ASCENT AND VERTICAL SHEAR TODAY WILL BE
DISPLACED TO THE N OF THE MORE UNSTABLE WARM SECTOR CLOSER TO THE
GULF COAST. RAIN AND EMBEDDED THUNDERSTORMS HAVE ALREADY SPREAD
EWD/NEWD INTO WRN TN/KY IN ADVANCE OF THE SURFACE LOW...WHERE
BOUNDARY LAYER DEWPOINTS ARE UNLIKELY TO EXCEED THE LOWER 60S AND
WARM SECTOR DESTABILIZATION IS IN QUESTION. FARTHER S/SW...A
MARITIME TROPICAL AIR MASS HAS PENETRATED INLAND ACROSS SE TX AND
SRN LA...AND 66-70 F DEWPOINTS WILL LIKELY MOVE INLAND TODAY ACROSS
MS/AL IN ADVANCE OF THE COLD FRONT AND PRE-FRONTAL SQUALL LINE.
MODEST MIDLEVEL LAPSE RATES AND SURFACE HEATING AHEAD OF THE
CONVECTIVE BAND WILL SUPPORT MLCAPE OF 1000-1500 J/KG GENERALLY S OF
I-20 THIS AFTERNOON...WITH MLCAPE DECREASING TO A FEW HUNDRED J/KG
CLOSER TO THE SURFACE CYCLONE ACROSS KY/SE INDIANA/SRN OH.
CONVECTION ACROSS WRN TN/NW MS/NRN LA EARLY THIS MORNING HAS
PROGRESSED ABOUT 50-100 MI AHEAD OF THE SURFACE COLD FRONT.
ADDITIONAL DESTABILIZATION TODAY BEHIND THIS BAND IS UNLIKELY GIVEN
THE THICK CLOUDS AND DEEP-LAYER PROFILE CHANGES NOTED AT SHV AND LZK
WITH PASSAGE OF THE STORMS. FARTHER SW...THE STORMS SHOULD REMAIN
MORE CLOSELY TIED TO THE FRONT ACROSS SE TX. LATER THIS MORNING AND
INTO THIS AFTERNOON...SOME INTENSIFICATION OF STORMS IS EXPECTED IN
A BROKEN BAND NEAR THE LEADING EDGE OF THE REMNANT PRE-FRONTAL LINE
ACROSS LA/MS...AND THE STORMS WILL SUBSEQUENTLY SPREAD EWD INTO AL.
SOMEWHAT UNIDIRECTIONAL WIND PROFILES BY AFTERNOON SUGGEST THAT
DAMAGING WINDS WITH LINE SEGMENTS WILL BE THE MAIN SEVERE STORM
THREAT. LOW-LEVEL SHEAR WILL BE STRONG ENOUGH IN THE MOIST
ENVIRONMENT TO SUPPORT THE RISK OF A TORNADO OR TWO WITH EMBEDDED
QLCS CIRCULATIONS...OR WITH ANY ISOLATED/DISCRETE STORMS THAT MANAGE
TO DEVELOP AHEAD OF THE LINE.
...E OF CENTRAL/SRN APPALACHIANS AFTER ABOUT 06Z...
THE COLD FRONT AND ASSOCIATED FRONTAL CONVECTION ARE NOT EXPECTED TO
REACH E OF THE APPALACHIANS UNTIL ROUGHLY 06Z. THOUGH INSTABILITY
WILL BE WEAK FROM SC NWD INTO VA...A GRADUAL INCREASE IN LOW-LEVEL
MOISTURE WILL ALLOW MUCAPE OF 250-500 J/KG ROOTED NEAR THE SURFACE.
DESPITE THE WEAK INSTABILITY AND A SHALLOW STABLE LAYER NEAR THE
GROUND...A STRONG LOW-MIDLEVEL VERTICAL SHEAR ENVIRONMENT EXPECTED
IN ADVANCE OF THE FRONT WILL SUPPORT A RISK FOR ISOLATED
Posted 23 November 2011 - 04:11
and rain and freezing rain is already falling over southern Ontario and I have just phoned my daughter Sheila in Cobourg Ontario and my other daughter Elizabeth in Toronto to watch out for freezing rain when driving in the warning. However Montreal is expected to get between 10 and 15 cms of snow and the snow will be heavy at times. It is now just after 11 pm on Tuesday evening on Tuesday 22nd November and the snow is getting close to Montreal as is visible on the radar.In fact I keep looking at the lamppost just outside to see if it has started yet. It is supposed to be at its worse during tomorrow morning's rush hour. I have dug out my winter boots, actually they are anti rattle snake boots that I bought a couple of years ago for walking around in the Sonora Desert in southern Arizona. I discovered that they also work very well as winter boots. The wind is from the East at about 14 mph but will almost certainly get stronger as the Low gets closer to us as it passes by to the south. It will be nice to see real snow again.
Posted 22 January 2012 - 20:38
SEVERE THUNDERSTORMS SHOULD INITIATE BY EARLY EVENING NEAR THE
ARKLATEX THEN RACE NEWD TOWARD WRN TN/NWRN MS AFTER DARK. DAMAGING
WINDS AND ISOLATED TORNADOES ARE EXPECTED. A TORNADO WATCH WILL
LIKELY BE REQUIRED BY 00Z.
Posted 22 January 2012 - 23:26
EFFECTIVE THIS SUNDAY AFTERNOON FROM 520 PM UNTIL MIDNIGHT CST.
...THIS IS A PARTICULARLY DANGEROUS SITUATION...
DISCUSSION...THUNDERSTORMS WILL INCREASE IN COVERAGE/INTENSITY THE
NEXT FEW HOURS ACROSS CENTRAL/ERN AR AS THE LOW LEVELS DESTABILIZE
AND ASCENT OVERSPREADS THE AREA FROM W TO E...IN ADVANCE OF A STRONG
SHORTWAVE TROUGH NOW OVER ERN OK. LOW-LEVEL SHEAR AND MOISTURE WILL
INCREASES THROUGH THE EVENING ACROSS NE AR/WRN TN...AND STORMS ARE
EXPECTED TO EVOLVE INTO A BROKEN BAND WITH BOTH EMBEDDED SUPERCELLS
AND EMBEDDED BOWING SEGMENTS. VERTICAL SHEAR...MOISTURE...AND THE
MIXED STORM MODES WILL FAVOR A RISK OF A FEW STRONG
TORNADOES...ALONG WITH DAMAGING WINDS AND LARGE HAIL THROUGH
Posted 23 January 2012 - 03:03
* AT 843 PM CST...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING
A LARGE AND EXTREMELY DANGEROUS TORNADO 25 MILES WEST OF WATKINS
CORNER...OR 7 MILES NORTH OF DE WITT...MOVING NORTHEAST AT 55 MPH.
http://www.katv.com/ - live coverage.
Posted 23 January 2012 - 10:51
Posted 23 January 2012 - 11:09
This post has been edited by Jez Meyer: 23 January 2012 - 11:09