FXUS64 KMEG 061139
AFDMEG
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
539 AM CST SUN DEC 6 2009
.UPDATE...
UPDATED TO ADD 12Z AVIATION DISCUSSION.
&&
.PREV DISCUSSION... /ISSUED 447 AM CST SUN DEC 6 2009/
DISCUSSION...
..ACTIVE PERIOD OF WEATHER TONIGHT THROUGH TUESDAY NIGHT FOR THE
MIDSOUTH INCLUDING THE POSSIBILITY OF A WINTRY MIX NORTH TONIGHT
AND SEVERE WEATHER POSSIBILITIES TUESDAY IN NORTHERN MISSISSIPPI...
TODAY THROUGH MONDAY...HIGH PRESSURE OVERHEAD WILL PROVIDE A DRY
AND QUIET DAY ACROSS THE MIDSOUTH TODAY. WEAK WARM AIR ADVECTION
IN PLACE THIS AFTERNOON SHOULD HELP BRING TEMPERATURES UP A LITTLE
OVER SATURDAY WITH HIGHS GENERALLY IN THE MID TO UPPER 40S.
LOW PRESSURE OVER THE PANHANDLE OF TEXAS LATE THIS AFTERNOON WILL
RACE NORTHEAST INTO THE GREAT LAKES BY MONDAY AFTERNOON. AS THIS
OCCURS...THERE WILL BE LITTLE TIME TO ADVECT DEEP MOISTURE
NORTHWARD. AS A RESULT...THE MID TO UPPER LEVELS WILL LIKELY
REMAIN RATHER DRY SO NO HEAVY PRECIPITATION IS EXPECTED
TONIGHT. HOWEVER...SUFFICIENT WARM AND MOIST AIR RETURN IN THE
900-700 MB LAYER WILL CAUSE A MOIST INVERSION TO SET UP
OVERNIGHT...LIKELY AFTER THE SURFACE HAS A CHANCE TO RADIATIONALLY
COOL. AIDING IN THIS COOLING PROCESS WILL BE MODERATE EVAPORATIVE
COOLING BROUGHT ON BY A LARGE DRY WEDGE OF AIR BELOW 900 MB. IF
THE SURFACE CAN COOL SUFFICIENTLY AS PRECIPITATION PUSHES
IN...THERE WOULD BE A GOOD CHANCE OF FREEZING RAIN AND SLEET
GENERALLY NORTH OF A LINE FROM CHERRY VALLEY ARKANSAS TO PARIS
TENNESSEE. BECAUSE OF THIS UNCERTAINTY...WILL HAVE RAIN OR
FREEZING RAIN AND SLEET MENTIONED IN THE GRIDS. DECIDED TO HOLD
OFF ON ANY HEADLINES FOR NOW DUE TO UNCERTAINTY...BUT WILL ISSUE
A SPECIAL WEATHER STATEMENT TO HIGHLIGHT THIS LIGHT ICING
POSSIBILITY. AREAS SOUTH OF THE AFOREMENTIONED LINE SHOULD REMAIN
ALL RAIN. THE PRECIP WILL PUSH SOUTHEAST DURING THE DAY
MONDAY...LIKELY LINGERING OVER NORTHERN MISSISSIPPI THROUGH
AFTERNOON.
MONDAY NIGHT THROUGH WEDNESDAY...A MUCH STRONGER LOW PRESSURE
SYSTEM WILL PUSH TO THE PANHANDLE OF TEXAS TUESDAY AFTERNOON AND
THEN TRACK ALONG A TIGHT BAROCLINIC ZONE NORTHEASTWARD INTO THE
SOUTHERN GREAT LAKES...BOMBING OUT AS A 965-975MB LOW BY WEDNESDAY
AFTERNOON. QUESTIONS STILL REMAIN HOW THIS SYSTEM WILL PLAY OUT
FOR THE MIDSOUTH...BUT IT NOW APPEARS A WARM FRONT WILL SURGE
NORTHWARD INTO PORTIONS OF NORTH MISSISSIPPI TUESDAY AFTERNOON.
THE WARM SECTOR MAY REMAIN OVER NORTHEAST MISSISSIPPI THROUGH
TUESDAY NIGHT BEFORE THE COLD FRONT SURGES IN FROM THE WEST
WEDNESDAY. WIDESPREAD RAIN WILL DEVELOP OVER THE MIDSOUTH EARLY
TUESDAY MORNING AND REMAIN IN PLACE THROUGH EARLY TUESDAY EVENING.
FORECAST SOUNDINGS INDICATE A VERY MOIST PROFILE WITH SOME
ELEVATED INSTABILITY OUTSIDE OF THE WARM SECTOR...AND THE
POSSIBILITY OF SURFACE BASED INSTABILITY IN THE WARM SECTOR IF
TEMPERATURES CAN WARM ENOUGH. EXTREMELY HIGH AMOUNTS OF LOW LEVEL
SHEAR WILL BE IN PLAY TUESDAY AFTERNOON AND THINGS COULD GET QUITE
INTERESTING IF THE WARM SECTOR DOES MAKE IT THIS FAR NORTH AND ANY
SBCAPE CAN DEVELOP. SPC DAY 3 HAS INCLUDED MUCH OF NORTHERN MS IN
A SLIGHT RISK FOR THE POSSIBILITY OF TORNADOES AND DAMAGING WINDS.
WILL BEEF UP THE THUNDER THREAT AREA WIDE...BUT ESPECIALLY IN THE
POTENTIAL WARM SECTOR REGION.
THE COLD FRONT WILL RACE EASTWARD LATE TUESDAY NIGHT OR WEDNESDAY
MORNING. GUSTY WINDS WILL IMMEDIATELY FOLLOW THE FRONT WITH SOME
GUSTS EXCEEDING 30 MPH POSSIBLE. STRONG CAA FOR WEDNESDAY NIGHT
WILL LIKELY BRING TEMPS INTO THE LOW OR MID 20S.
THURSDAY THROUGH NEXT SATURDAY...ANOTHER PERIOD OF BELOW NORMAL
TEMPERATURES ARE LIKELY DURING THIS PERIOD AS MODIFIED ARCTIC AIR
SPILLS DOWN TO THE GULF COAST. HIGH PRESSURE SHOULD REMAIN IN
CONTROL THROUGH FRIDAY MORNING BEFORE ANOTHER WEAK SYSTEM PUSHES
NORTHEASTWARD FROM THE WESTERN GULF. WITH COLD AIR IN PLACE AND
NO STRONG SURFACE WAA...COULD SEE ANOTHER MIXY SCENARIO FOR THE
NORTHERN CWA FRIDAY NIGHT.
BORGHOFF
&&
.AVIATION...
12Z TAF CYCLE
VFR CONDITIONS EXPECTED AT TAF SITES THROUGH AT LEAST 07/06Z THEN
DETERIORATING TO MVFR CONDITIONS THEREAFTER AS A COLD FRONT MOVES
THROUGH ALL TERMINALS. MAIN QUESTION AT THIS POINT IS
PRECIPITATION TYPE FOR JBR/MKL. ALTHOUGH THERE IS A SLIGHT POTENTIAL
FOR SOME VERY LIGHT FREEZING RAIN/SLEET/FREEZING DRIZZLE AT
JBR/MKL...WILL HOLD OFF FROM INCLUDING IN THESE FORECASTS DUE TO
UNCERTAINTY AND LET DAY SHIFT REASSESS ANY POTENTIAL AVIATION
WINTER WEATHER IMPACTS FOR JBR/MKL TONIGHT. WILL BRING IN LIGHT RAIN
THIS EVENING AT JBR AND SPREAD EAST TO MEM AROUND 07/05Z...AND
REMAINING SITES ON/AFTER 07/09Z.
CJC
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 47 34 47 39 / 10 80 10 60
MKL 46 33 46 35 / 0 70 20 40
JBR 45 32 46 34 / 10 70 10 40
TUP 47 35 49 42 / 0 60 50 60
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
