FXUS64 KMEG 051540
AFDMEG
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEMPHIS TN
940 AM CST SAT DEC 5 2009
.DISCUSSION...
SKIES ARE SUNNY ACROSS THE ENTIRE FORECAST AREA THIS MORNING WITH
TEMPERATURES FROM THE MID 20S TO MID 30S. WILL NEED TO SEND AN
UPDATE TO FORECAST TO REMOVE SOME MORNING WORDING BUT REMAINDER OF
FORECAST LOOKS FINE SO NO BIG CHANGES ARE PLANNED AT THIS TIME.
ARS
&&
.PREV DISCUSSION... /ISSUED 540 AM CST SAT DEC 5 2009/
UPDATE...
UPDATED TO ADD 12Z AVIATION DISCUSSION.
PREV DISCUSSION... /ISSUED 452 AM CST SAT DEC 5 2009/
DISCUSSION...
A RATHER CHALLENGING FORECAST FOR THE UPCOMING WEEK. AT DISCUSSION
TIME...ARCTIC HIGH PRESSURE AXIS EXTENDED FROM SOUTHERN IL...
THROUGH THE MIDSOUTH...INTO EAST TX. TEMPERATURES WERE IN THE
UPPER TEENS AND 20S. THIS VERY DRY AIRMASS SHOULD WARM INTO THE
40S UNDER SUNNY SKIES TODAY. TONIGHT WILL SEE THE WESTERN SIDE OF
THE ARCTIC HIGH OVER THE MIDSOUTH...WITH TEMPERATURES DROPPING INTO
THE UPPER TEENS OVER THE TN RIVER VALLY AND 20S ELSEWHERE.
SUNDAY SHOULD SEE INCREASING HIGH CLOUDS AHEAD AN UPPER LEVEL WAVE
LIFTING INTO THE MID MS RIVER VALLEY. GFS SHEARS THE SOUTHERN LOBE
OF THIS SHORTWAVE THROUGH THE MIDSOUTH EARLY MONDAY...LIKELY
OVERDOING QPF /UP TO 0.75 INCH/ INTO THE DRY SUBCLOUD LAYER. SO
WHILE POPS ARE IN THE HIGH CHANCE TO LIKELY CATEGORY...MEASURED
AMOUNTS SHOULD BE ON THE LIGHT SIDE BY THE TIME THIS SYSTEM EXITS
ON MONDAY. WILL NEED TO WATCH FOR FREEZING DRIZZLE POTENTIAL ON
THE BACKSIDE OF THIS SYSTEM EARLY MONDAY MORNING. BASED ON THE
NAM/GFS SOUNDINGS...HAVE INTRODUCED A MENTION OF FREEZING DRIZZLE
OVER NORTHEAST AR AND THE MO BOOTHEEL.
THE NEXT DEEPER UPPER LEVEL TROF WILL EJECT FROM THE CENTRAL
ROCKIES INTO THE PLAINS ON TUESDAY. GFS DEVELOPS A 992MB SURFACE
LOW OVER NORTHERN OK. A DOWNSTREAM 1000MB SURFACE LOW IS ALSO
PROGGED OVER NORTH MS TUESDAY AFTERNOON...FORMED UNDER STRONG
DIFFLUENCE ALOFT. EXPECT WIDESPREAD SHOWERS ACROSS THE MIDSOUTH
TUESDAY...WITH ISOLATED THUNDER NEAR AND TO THE SOUTH OF THE
NORTH MS SURFACE LOW.
STRONG COLD ADVECTION WILL OCCUR ON WEDNESDAY...BEHIND THE EXITING
UPPER LEVEL TROF. MAY SEE SNOW MIX IN AGAIN OVER THE NORTHERN
AREAS EARLY IN THE DAY WEDNESDAY. THIS PRECIP WOULD BE ASSOCIATED
WITH STREAMWISE ENERGY ON THE BACKSIDE OF THE DEPARTING UPPER LOW.
AMOUNTS SHOULD BE VERY LIGHT...IF EVEN MEASURABLE...GIVEN THE DRY
AIRMASS. GFS MOS GUIDANCE APPEARS FAR TOO WARM FOR WEDNESDAY/S MAX
TEMPS....SIMPLY NOT HANDLING THE COLD ADVECTION...CLOUDY SKIES AND
EVAPORATIVE COOLING OF PRECIP INTO THE VERY DRY ARCTIC AIRMASS.
MAY HAVE TO UNDERCUT WEDNESDAY/S TEMPS FURTHER IF FUTURE IF FUTURE
GFS/ECMWF MODEL RUNS HOLD TO THE CURRENT SOLUTION.
THE ARCTIC SURFACE HIGH CENTER SHOULD MOVE ACROSS THE MIDSOUTH
THURSDAY...SETTLING NEAR THE CAROLINA COAST BY FRIDAY MORNING. SHOULD
SEE LOW LEVEL SOUTHERLY RETURN FLOW STRENGTHEN ON FRIDAY...IN ADVANCE
OF AN UPPER LEVEL TROF. BY LATE FRIDAY NIGHT...THE GFS DEVELOPS
PRECIP NEAR A STATIONARY BOUNDARY ACROSS THE MIDSOUTH...UNDER THE
RIGHT ENTRANCE REGION OF AN UPPER JET STREAK. PRETTY FAR OUT TO
RAISE FLAGS OF CONCERN. BUT THIS PATTERN...IF VERIFIED...COULD
LEAD TO A FREEZING DRIZZLE OR FREEZING RAIN EVENT ON THE NORTH
SIDE OF THE FRONT. THE ECMWF MODEL WAS IN VERY TIGHT AGREEMENT
WITH THE GFS ON THE LATE WEEK PATTERN.
WITH ARCTIC AIR EDGING INTO THE MIDSOUTH AT VARIOUS TIMES IN THE
UPCOMING WEEK...WILL NEED TO CLOSELY MONITOR THE POTENTIAL FOR
FREEZING PRECIPITATION AT VARIOUS TIMES DURING THE UPCOMING WEEK.
PWB
AVIATION...
12Z TAF CYCLE
VFR CONDITIONS EXPECTED THROUGH THE ENTIRE TAF PERIOD. NORTHWEST TO
NORTH WINDS AROUND 7 KTS AT MEM/MKL/TUP AND SOUTH WINDS AROUND
7KTS AT JBR BECOMING LIGHT BY 06/00Z.
CJC
&&
.PRELIMINARY POINT TEMPS/POPS...
MEM 44 28 51 37 / 0 0 10 70
MKL 41 20 50 35 / 0 0 0 60
JBR 44 24 47 32 / 0 0 10 50
TUP 42 23 50 37 / 0 0 0 60
&&
.MEG WATCHES/WARNINGS/ADVISORIES...
AR...NONE.
MO...NONE.
MS...NONE.
TN...NONE.
&&
$$
