FXUS64 KMEG 021556
AFDMEG
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
956 AM CST WED DEC 2 2009
.DISCUSSION...
A SURFACE LOW WHICH WAS OVER NORTH MISSISSIPPI AT 15Z WILL TRACK
TO KENTUCKY BY SUNSET. THE ASSOCIATED UPPER LOW OVER THE ARKLATEX
WILL MOVE OVER THE CWA THIS AFTERNOON. A DRY SLOT IS PUSHING INTO
NORTHEAST MISSISSIPPI FROM THE SOUTH WHICH WILL REDUCE THE RAIN
COVERAGE OVER THAT AREA THIS AFTERNOON. THE APPROACHING UPPER LOW
WILL KEEP THE RAIN CHANCE HIGH OVER THE WESTERN AREAS THROUGHOUT
THE DAY. THE CURRENT FORECAST HAS THIS SCENARIO HANDLED VERY WELL.
SWC
&&
.PREV DISCUSSION... /ISSUED 442 AM CST WED DEC 2 2009/
DISCUSSION...FORECAST FOCUS ON RAIN TODAY AND THIS EVENING THEN
ON MUCH COOLER CONDITIONS AND POSSIBILITIES FOR SNOW FRIDAY
NIGHT.
TODAY AND TONIGHT...
AT 10Z...LOW PRESSURE WAS LOCATED NEAR NEW ORLEANS AND RADAR
INDICATED RAINFALL WAS BECOMING MORE WIDESPREAD ACROSS CENTRAL AND
WESTERN PORTIONS OF THE CWA. RAIN WILL CONTINUE TO BECOME MORE
WIDESPREAD THROUGH THE MORNING AS MOISTURE INCREASES AND
ISENTROPIC LIFT BECOMES STRONGER. BY 18Z...A PRONOUNCED TROWAL IS
EXPECTED TO BECOME ESTABLISHED ACROSS TENNESSEE...EASTERN
ARKANSAS...AND THE BOOTHEEL. THIS IS WHERE THE HEAVIEST AND MOST
WIDESPREAD RAIN WILL BE LOCATED. WILL MENTION POSSIBILITY OF HEAVY
RAIN IN THESE AREAS MAINLY FOR THIS MORNING. IN FACT ALREADY
BEGINNING TO SEE SOME 45 DBZ RETURNS OVER EASTERN ARKANSAS WITH
HEAVY RAIN OBSERVED OVER PORTIONS OF CENTRAL AND SOUTHERN
ARKANSAS.
THE LOW IS EXPECTED TO TRACK ACROSS NORTHEAST MISSISSIPPI LATE
THIS MORNING AND A DRY SLOT SHOULD SOON FOLLOW. THEREFORE...WILL
REDUCE RAIN CHANCES TO THE CHC CATEGORY ALONG AND SOUTHEAST OF THE
LOW TRACK THIS AFTERNOON. SOME WRAP AROUND SHOWERS MAY SWING
THROUGH THE MIDSOUTH THIS EVENING...SO LEFT A CHANCE OF RAIN IN
UNTIL ABOUT MIDNIGHT. COLD AIR SHOULD STILL LAG BEHIND LONG
ENOUGH TO PRECLUDE MENTION OF ANY SNOW.
THURSDAY THROUGH SATURDAY...
COLD AIR ADVECTION AND DRY CONDITIONS WILL BE THE WEATHER HEADLINE
FOR THURSDAY AND FRIDAY. IT APPEARS THERE WILL BE A SUFFICIENT
AMOUNT OF MID LEVEL MOISTURE FOR SOME CLOUDS. GENERALLY UNDERCUT
GUIDANCE BY AT LEAST A FEW DEGREES FOR TEMPERATURES DURING THIS
PERIOD AFTER LOOKING AT 925 MB TEMPS AND THE POSSIBILITY OF SOME
CLOUDS.
A SECOND SURGE SOUTHWARD OF THE LONG WAVE TROUGH IS EXPECTED TO
OCCUR THURSDAY. THIS WILL FORCE AN UPPER LEVEL DISTURBANCE TO DIVE
INTO SOUTHERN TEXAS THURSDAY NIGHT AND SPAWN A SURFACE LOW OVER
THE WESTERN GULF FRIDAY. MODELS HAVE BEEN STRUGGLING WITH THE
EVOLUTION OF THIS LOW AND REMAIN INCONSISTENT FOR THIS FORECAST
PACKAGE. THE ECMWF AND CANADIAN WANT TO KEEP THE LOW WELL SOUTH
AND POSITIVELY TILTED...PREVENTING IT FROM STRENGTHENING MUCH AND
KEEPING THE MIDSOUTH DRY. THE NAM AND GFS ARE A LITTLE FURTHER
NORTH...ALSO KEEP IT POSITIVELY TILTED...BUT SPREADS SOME LIGHT
QPF OVER NORTHERN MISSISSIPPI. TEMPERATURES THROUGH THE ATMOSPHERE
WILL BE COLD ENOUGH TO SUPPORT ALL SNOW. IF THE TROUGH CAN DIG A
LITTLE BIT MORE ON THE BACKSIDE OF THIS THING...THERE IS MORE THAN
ENOUGH THICKNESS PACKING AND BAROCLINIC INSTABILITY TO WIND THIS
LOW UP. NEEDLESS- TO-SAY THIS HAS LARGE IMPLICATIONS ON THE
FORECAST FRIDAY NIGHT AND SATURDAY MORNING. FORECAST SOUNDINGS ON
THE NAM AND GFS INDICATE A RATHER MOIST SOUNDING FRIDAY NIGHT NEAR
KTUP. FELT THE SITUATION WARRANTED A CHANCE FOR LIGHT SNOW FOR THE
SOUTHERN AND EASTERN COUNTIES. ONLY MINOR ACCUMULATIONS /HALF INCH
OR LESS/ ARE EXPECTED AT THIS POINT...BUT THE SITUATION WILL NEED
TO BE WATCHED OVER THE NEXT COUPLE OF DAYS.
SATURDAY NIGHT THROUGH NEXT TUESDAY...
HIGH PRESSURE BUILDS IN QUICKLY SATURDAY NIGHT AND SUNDAY. MODELS
THEN DIVERGE FOR EARLY TO MIDDLE NEXT WEEK REGARDING A STORM
SYSTEM ORGANIZING OVER THE SOUTHERN PLAINS. MODEL CONSISTENCY HAS
BEEN POOR WITH THIS FEATURE...THUS WILL LEAVE THE CHANCES OF RAIN
IN THERE FOR MONDAY NIGHT AND TUESDAY.
BORGHOFF
&&
.AVIATION...
12Z TAFS
DEEP UPPER LEVEL LOW PRESSURE WAS CENTERED OVER EAST TX AT
DISCUSSION AT 1145Z...LIFTING NORTHEAST. WIDESPREAD SHOWERS HAD
MOVED INTO THE MIDSOUTH AHEAD OF THIS FEATURE EARLIER THIS
MORNING. MVFR CIGS HAVE GIVEN WAY TO IFR OVER NORTH MS DURING THE
NIGHT...AND JUST RECENTLY AT KMEM.
A MIDLEVEL DRY SLOT WILL LIKELY BRING REDUCED COVERAGE OF RAIN IN
THE MID TO LATE MORNING PERIODS...BUT NOT LIKELY A SIGNIFICANT
IMPROVEMENT IN CIGS. THE UPPER LOW CORE SHOULD PASS NEAR OR JUST
NORTH OF KMEM AROUND 21Z...AND EXPECT TO SEE A SECONDARY ROUND OF
RAIN DURING THE AFTERNOON.
ONCE AN ASSOCIATED SURFACE COLD FRONT IN THE 22Z TO 03Z TIME
FRAME... EXPECT TO SEE CIGS TO CLIMB ABOVE FL020 AT ALL BUT
PERHAPS KTUP.
PWB
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 49 33 46 31 / 100 30 0 0
MKL 48 32 46 26 / 100 30 0 0
JBR 46 33 43 27 / 100 30 0 0
TUP 53 35 48 31 / 80 30 0 0
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
