FXUS64 KMEG 011141 AAA
AFDMEG
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MEMPHIS TN
541 AM CST TUE DEC 1 2009
.UPDATE...
UPDATED FOR AVIATION.
&&
.PREV DISCUSSION... /ISSUED 448 AM CST TUE DEC 1 2009/
DISCUSSION...FORECAST FOCUS ON STRONG STORM SYSTEM FOR TONIGHT
THROUGH WEDNESDAY NIGHT...THEN ON UNSEASONABLY COLD CONDITIONS
FOR LATE WEEK AND THIS WEEKEND.
TODAY...AT 10Z...A 1008 MB LOW WAS LOCATED OVER WEST CENTRAL
GULF OF MEXICO WITH SURFACE HIGH PRESSURE OVER THE MIDSOUTH. THE
HIGH WILL KEEP THE LOW NEARLY STATIONARY TODAY. HIGH CLOUDS WILL
BEGIN TO STREAM NORTHWARD INTO THE CWA THIS MORNING WHICH WILL
THICKEN AND LOWER THIS AFTERNOON AS HIGH PRESSURE HEADS EAST AND
MOISTURE BEGINS TO INCREASE. TEMPERATURES TODAY SHOULD BE THE
WARMEST OF THE NEXT 7 DAYS...REACHING THE MID TO UPPER 50S.
TONIGHT THROUGH WEDNESDAY NIGHT...THE SUBTROPICAL JET ACROSS
NORTHERN MEXICO WILL DIG SOUTH OF THE SURFACE LOW THIS EVENING...
CAUSING IT TO BEGIN EJECTING NORTHEASTWARD. THE GFS AND ECMWF ARE
FINALLY IN DECENT AGREEMENT WITH TAKING THE SURFACE LOW ACROSS NEW
ORLEANS TONIGHT AND INTO EASTERN KENTUCKY BY WEDNESDAY AFTERNOON.
THE NAN AND CANADIAN ARE QUITE A BIT FURTHER WEST AND TAKE IT
ACROSS NORTHEASTERN MISSISSIPPI AND CENTRAL KENTUCKY. USUALLY I
WOULD FAVOR THE GFS/ECMWF COMBO BUT RAPIDLY DEEPENING SYSTEMS CAN
TRACK FURTHER WEST THAN MODELS EVER INDICATE. THEREFORE...WILL
USE A COMPROMISE BETWEEN THE TWO SOLUTIONS. REGARDLESS OF THE
TRACK...RAIN WILL OVERSPREAD THE CWA FROM SOUTH TO NORTH LATE THIS
EVENING AND OVERNIGHT. AS THE SURFACE LOW TRACKS TO THE NORTHEAST
OF THE CWA...ALL MODELS HINT AT A DRY SLOT PUSHING INTO NORTHEAST
MISSISSIPPI LATE WEDNESDAY MORNING AND AFTERNOON. AFTER
CATEGORICAL POPS IN THE MORNING...POP WAS REDUCED TO CHANCE AFTER
18Z THERE. MEANWHILE...THE DEFORMATION BAND WILL LIKELY CENTER
ITSELF OVER EASTERN ARKANSAS...WESTERN TENNESSEE...AND FAR
NORTHWEST MISSISSIPPI WEDNESDAY. RAIN MAY BE HEAVY AT TIMES WITHIN
THIS BAND GIVEN STRENGTH OF THE FORCING AND HIGH AMOUNTS OF
MOISTURE. THERE MAY BE A CLAP OR TWO OF THUNDER AS WELL...BUT WILL
LEAVE OUT OF GRIDS ATTM.
CHANCES FOR SNOW OF ANY CONSEQUENCE APPEAR TO BE DIMINISHING ON
THE BACKSIDE OF THIS SYSTEM. WITH EACH MODEL RUN...IT TAKES LONGER
AND LONGER FOR CRITICAL THICKNESSES AND FREEZING SURFACE TEMPS TO
MAKE IT INTO THE MIDSOUTH BEFORE THE MAIN SLUG OF MOISTURE EXITS.
LEFT THE MENTION OF RAIN/SNOW IN FOR AREAS NORTHWEST OF KJBR FOR
NOW...BUT THE SNOW MAY HAVE TO BE REMOVED IN LATER FORECASTS.
AFTER MIDNIGHT HOWEVER...COLD TEMPERATURES WILL SURGE EASTWARD
AND THERE MAY BE ENOUGH LINGERING MOISTURE AND INSTABILITY IN THE
LOW LEVELS TO PRODUCE A COUPLE FLURRIES MAINLY NORTH OF I-40.
GUSTY WINDS ANTICIPATED WEDNESDAY NIGHT DUE TO STRONG CAA. COULD
SEE GUSTS APPROACH 30 MPH.
THURSDAY THROUGH NEXT MONDAY...UPPER TROUGH BEGINS TO PUSH
EASTWARD TOWARD THE MIDSOUTH THURSDAY. CONTINUING COLD AIR
ADVECTION AND CLOUDS SHOULD KEEP HIGHS FROM MAKING IT MUCH ABOVE
THE LOWER OR MIDDLE 40S. COME FRIDAY...THE TROUGH WILL BE CENTERED
JUST WEST OF THE AREA AND THICKNESSES WILL DIP INTO THE 528-534
DAM RANGE. ASSUMING EVEN A SUPER ADIABATIC PROFILE FROM 925 WITH
925 MB TEMPS OF -2 TO -4C MEANS HIGHS WILL LIKELY STAY IN THE 30S
OVER THE NORTH HALF AND STRUGGLE TO REACH THE MID 40S FAR SOUTH.
MODELS DIVERGE A BIT FRIDAY AFTERNOON AND FRIDAY NIGHT. ANOTHER
DISTURBANCE WILL ATTEMPT TO GET ITS ACT TOGETHER OVER THE WESTERN
GULF FRIDAY AFTERNOON AND TRACK ACROSS NORTHERN FLORIDA FRIDAY
NIGHT. THE 06Z GFS NOW HALTS THE EASTWARD PROGRESSION OF THE
TROUGH BEYOND FRIDAY AFTERNOON AND SPREADS QPF ASSOCIATED WITH
THIS LOW OVER THE SOUTHERN HALF OF THE CWA FRIDAY NIGHT. THIS
PRECIPITATION WOULD REMAIN ALL SNOW GIVEN THICKNESSES BELOW 534
DAM AND SURFACE TEMPS BELOW FREEZING. THE 00Z ECMWF HINTS AT SOME
PRECIPITATION OVER THE SAME AREA...HOWEVER IT KEEPS THE BRUNT OF
THE MOISTURE MUCH FURTHER SOUTH AND KEEPS THE UPPER TROUGH
PROGRESSING EASTWARD. FOR NOW WILL KEEP IT DRY WHICH HAS BEEN THE
MOST CONSISTENT SOLUTION. IF IT REMAINS CLEAR AND THE TROUGH AXIS
PUSHES OVERHEAD...MANY LOCATIONS IN THE TENNESSEE RIVER VALLEY
COULD FALL INTO THE TEENS FRIDAY NIGHT.
SURFACE HIGH PRESSURE THEN SETTLES ITSELF OVER THE MIDSOUTH FOR
THE WEEKEND...WITH A SLIGHT WARMING TREND EXPECTED.
BORGHOFF
&&
.AVIATION...
12Z TAFS
VFR CONDITIONS EXPECTED TO PREVAIL ACROSS THE MIDSOUTH TERMINALS
TODAY WITH BROKEN CIRRUS PREVAILING. SURFACE HIGH PRESSURE CENTERED
NEAR KMEM AT DISCUSSION TIME SLIDE OFF TO THE EAST...RESULTING IN
LIGHT EAST/SOUTHEAST WINDS AT THE MIDSOUTH TERMINALS.
BROKEN CIRRUS WILL GIVE WAY TO SCATTED MIDLEVEL CLOUDS TOWARD 06Z.
A BROKEN MVFR LAYER WILL LIKELY MOVE NORTH INTO THE KTUP AREA
AFTER 06Z...IN RESPONSE TO DEEPENING ONSHORE FLOW AHEAD OF AN
APPROACHING UPPER LEVEL LOW. THESE MVFR CIGS AND SCATTERED SHOWERS
WILL APPROACH THE KMEM/KMKL TAF SITES IN THE LATER HOURS OF THE
TAF...NEAR OR JUST FOLLOWING THE KMEM OUTBOUND PUSH.
PWB
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 59 44 48 33 / 0 100 100 40
MKL 58 44 46 33 / 0 80 100 60
JBR 56 40 45 31 / 0 70 100 50
TUP 56 44 51 37 / 0 100 80 30
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
