FXUS64 KMEG 071808
AFDMEG
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
1208 PM CST MON DEC 7 2009
.UPDATE...
UPDATED AVIATION.
&&
.DISCUSSION...
/ISSUED 939 AM CST MON DEC 7 2009/
MOSTLY CLOUDY SKIES PREVAILED ACROSS THE MID SOUTH THIS MORNING
WITH TEMPERATURES IN THE 30S TO LOW 40S FAHRENHEIT AS OF 9 AM. THE
CURRENT SHORT TERM FORECAST APPEARS TO BE ON TRACK. WILL WAIT FOR
THE COMPLETE 12Z COMPUTER MODEL GUIDANCE BEFORE COMMENTING ON THE
POTENTIAL HEAVY RAIN AND SEVERE WEATHER EVENTS ON TUESDAY AND
TUESDAY NIGHT.
OKULSKI
&&
.PREV DISCUSSION... /ISSUED 439 AM CST MON DEC 7 2009/
DISCUSSION...FORECAST FOCUS ON THE POWERFUL WINTER STORM TRACKING
TO THE NORTH AND IT/S AFFECTS ON THE MIDSOUTH...THEN ON MORE
WINTRY CONDITIONS POSSIBLE LATER THIS WEEK.
TODAY THROUGH TUESDAY NIGHT...
AS OF DISCUSSION ISSUANCE TIME...BATCH OF RAIN SHOWERS EXTENDED
ACROSS WESTERN TENNESSEE AND NORTHERN MISSISSIPPI. THIS BATCH OF
RAIN WILL CONTINUE PUSHING EAST THIS MORNING ALONG WITH A WEAK
COLD FRONT. SO FAR THE VAST MAJORITY OF THIS PRECIPITATION HAS
REMAINED AS RAIN...ALTHOUGH STILL CAN/T COMPLETELY RULE OUT A
COUPLE SLEET PELLETS GIVEN SOME LOCATIONS REMAINING IN THE LOW TO
MID 30S.
THE COLD FRONT WILL WASH OUT LATE THIS AFTERNOON JUST EAST OF THE
CWA AS A MUCH STRONGER SYSTEM EMERGES OVER THE SOUTHERN COLORADO
ROCKIES LATE TONIGHT. ISENTROPIC LIFT AND MOISTURE WILL INCREASE
RAPIDLY THIS EVENING AND RAIN IS EXPECTED TO BLOSSOM ACROSS THE
CWA AFTER MIDNIGHT. STILL LOOKS LIKE SOME ELEVATED INSTABILITY
WILL BE ABLE TO BE TAPPED INTO...SO INSERTED A CHANCE OF THUNDER
EVERYWHERE EXCEPT THE FAR NORTH.
WIDESPREAD RAIN AND THUNDERSTORMS SHOULD CONTINUE THROUGH THE DAY
TUESDAY AND INTO TUESDAY NIGHT. ALL OPERATIONAL MODELS SHOW THE
SOUTHEAST THIRD TO SOUTHEAST HALF OF THE CWA GETTING INTO THE WARM
SECTOR BY LATE AFTERNOON. THIS MAY BE DIFFICULT TO DO CONSIDERING
THE WIDESPREAD RAIN...BUT IT MAY STILL BE POSSIBLE GIVEN THE
STRONG SOUTHERLY FLOW THROUGH THE LOWER LAYERS OF THE ATMOSPHERE.
BEHIND THE WARM FRONT...TEMPS MAY JUMP INTO THE 60S WITH DEW
POINTS ALSO APPROACHING 60. FORECAST SOUNDINGS INDICATE A VERY
MOIST COLUMN WITH PW/S AROUND AN INCH AND A HALF. WITH THE MOIST
ATMOSPHERE...THE STRONG LOW LEVEL JET OF 50-60 KNOTS...THE STRONG
ISENTROPIC LIFT AND THE WARM FRONT NEARBY...WE COULD SEE HEAVY RAIN
AND FLOODING. THE NAM AND ECMWF PAINT AN OMINOUS PICTURE WITH A
BAND OF TRAINING SHOWERS AND THUNDERSTORMS ALONG THE WARM FRONT
TUESDAY AND TUESDAY EVENING OVER NORTHERN MISSISSIPPI AND SOUTHERN
TENNESSEE. QPF TOTALS WITH THESE MODELS EXCEED 2.5-3.0 INCHES IN
SPOTS. HPC WAIVED SOME OF THIS OFF AS BEING AN ARTIFACT OF TOO
MUCH MOISTURE ADVECTION BUT WITH A LOW BOMBING OUT TO AROUND 975
MB...THE STRONG SOUTHERLY FLOW SHOULD BE ABLE TO QUICKLY BRING
MOISTURE NORTHWARD. THOUGHT ABOUT POSTING A FLASH FLOOD WATCH...
BUT WILL HOLD OFF FOR NOW DUE TO SOME UNCERTAINTY. INSTEAD...PUT
HEAVY RAIN MENTION IN THE GRIDS...WILL ISSUE AN ESF...AND WILL
MENTION FLOODING POTENTIAL IN THE HWO.
THE SEVERE THREAT WILL REMAIN CONDITIONAL ON HOW MUCH SURFACE BASED
INSTABILITY WE CAN TAP INTO...BUT THE CURRENT THINKING REMAINS THE
SAME IN THAT THE RAIN AND CLOUDS WILL HAMPER TEMPS SOMEWHAT AND
LAPSE RATES WILL REMAIN MEAGER. SPC DAY 2 CONTINUES TO MENTION A
LOW END SLIGHT RISK OF SEVERE FOR THE MISSISSIPPI COUNTIES. GIVEN
THE STRONG SHEAR AND VERY STRONG WINDS ALOFT...IT WON/T TAKE TOO
MUCH TO BRING SOME OF THAT ENERGY TO THE SURFACE IN ANY SUSTAINED
DOWNDRAFTS. THE TORNADO THREAT WILL MORE HEAVILY DEPEND ON THE
INSTABILITY FACTOR.
DRY SLOT WILL PUNCH INTO THE CWA FROM THE SOUTHWEST TUESDAY
EVENING AND THE COLD FRONT WILL FOLLOW. STRONG NORTHWEST WINDS
THEN EXPECTED WITH GUSTS POSSIBLY EXCEEDING 35 MPH TUESDAY NIGHT.
WEDNESDAY THROUGH NEXT SUNDAY...
STRONG COLD AIR ADVECTION WILL PREVENT TEMPS FROM WARMING TOO MUCH
WEDNESDAY...AND IF ANYTHING THEY MAY FALL THROUGH THE DAY. HIGH
PRESSURE WILL CENTER ITSELF OVER THE SOUTHERN PLAINS WEDNESDAY
NIGHT MAKING FOR A COLD NIGHT IN THE UPPER TEENS TO LOWER 20S.
THE HIGH WILL PUSH EAST ACROSS THE MIDSOUTH THURSDAY AND THURSDAY
NIGHT WITH CONTINUED COLD TEMPERATURES. THEN THE NEXT SYSTEM TO
WATCH WILL DEVELOP OVER SOUTHERN TEXAS OR THE WESTERN GULF FRIDAY.
WITH ARCTIC HIGH PRESSURE NEARLY STATIONARY OVER THE OHIO VALLEY
AND MID ATLANTIC...IT APPEARS THERE WILL BE ENOUGH COLD AIR AROUND
TO SUPPORT SNOW OR A WINTRY MIX FRIDAY...FRIDAY NIGHT...AND
SATURDAY. THIS BEARS WATCHING FOR POTENTIAL LIGHT ACCUMULATIONS.
BORGHOFF
&&
.AVIATION...
18Z TAF CYCLE
MVFR CEILINGS EXPECTED MOST OF THE AFTERNOON...EXCEPT SOME IFR
CONDITIONS IN NE MS. EXPECT SOME CEILING IMPROVEMENT LATE
AFTERNOON INTO EARLY EVENING...BUT LOWER CEILINGS WILL RE-OCCUR
TONIGHT AND BECOME IFR BEFORE DAYBREAK. RAIN WILL SPREAD ACROSS THE
AREA AFTER MIDNIGHT AND CONTINUE THROUGH 18Z TUE. WINDS WILL VARY
FROM NE TO SE 3-8 KTS DEPENDING ON THE TIME AND LOCATION.
SWC
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 48 43 59 44 / 10 90 100 80
MKL 46 39 57 43 / 10 80 100 100
JBR 46 35 48 38 / 10 80 100 50
TUP 46 43 62 48 / 60 90 100 100
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
