FXUS64 KJAN 010034 AAA
AFDJAN
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
634 PM CST MON NOV 30 2009
.UPDATE...HAVE REMOVED THE ENDING LAKE WIND ADVISORY FOR THE LARGER
LAKES AS SURFACE HIGH(1022MB) SETTLING FROM ERN OK INTO THE MID
SOUTH AND TN VALLEY THROUGH EARLY TUESDAY. LATEST NAM12/GFS RUNS
HOLD MEASUREABLE RAINS BACK UNTIL ABOUT MID AFTERNOON TUESDAY BEFORE
RAPIDLY SURGING NWD ACROSS THE SRN HALF OF OUR CWFA BY 6PM. 15Z SREF
BRINGS RAINS A LITTLE FASTER BUT MUCH OF THE LEADING EDGE PROBABLY
JUST SPRINKLES. NO OTHER CHANGES TO CURRENT FORECAST AS WE WATCH THE
FIRST DECENT GULF CYCLOGENESIS OF THE COLD SEASON TAKE SHAPE THROUGH
WEDNESDAY. /40/
&&
.PREV DISCUSSION... /ISSUED 400 PM CST MON NOV 30 2009/
DISCUSSION...THE COLD FRONT RESPONSIBLE FOR THE WIDESPREAD RAIN
ACROSS THE LOWER MS VALLEY OVER THE PAST 24 HOURS HAS PUSHED EAST OF
THE ARKLAMISS. THERE MAY BE A SPRINKLE OR TWO THAT LINGERS OVER
SOUTHEAST MS THROUGH DARK...BUT OTHERWISE THE PRECIPITATION SHOULD
BE DONE THROUGH TONIGHT FOR THE FORECAST AREA. BUT ANOTHER BIG
WEATHER MAKER IS NOT FAR AWAY AND HIGHER CLOUDS STREAMING UP
NORTHEAST FROM THIS SYSTEM INTO OUR NECK OF THE WOODS ARE A SIGNAL
OF ITS APPROACH.
THESE HIGH CLOUDS ARE MAKING FOR A TRICKY TEMP FORECAST TONIGHT. A
SEASONABLY CHILLY AIRMASS HAS DROPPED DOWN IN THE WAKE OF THE
INITIAL COLD FRONT AND MIGHT HAVE THE POTENCY TO DROP READINGS WAY
DOWN INTO THE 30S FOR ALL AREAS TONIGHT ON A CLEAR NIGHT. BUT IT
WILL NOT BE TOTALLY CLEAR WITH CIRRUS GRADUALLY INCREASING AS THE
NIGHT GOES ON. THINKING THAT CIRRUS ALONG AND SOUTH OF I-20 SHOULD
BE THICK ENOUGH TO LIMIT COOLING AND THUS LOWS MAY HANG AROUND 40.
BUT THIS MAY NOT BE THE CASE IN NORTHERN ZONES WHERE I CUT MAV TEMPS
A LITTLE FOR TONIGHT. HIGHER CLOUDS WILL BE INCREASING FURTHER
ACROSS THE WHOLE AREA TOMORROW AS THE MENTIONED SYSTEM GETS CLOSER.
BY AFTERNOON AN ASSOCIATED SURFACE LOW WILL BE STRENGTHENING AS IT
HEADS TOWARD THE LA COASTLINE. THE PRESENCE OF THIS LOW AND
INSTABILITY SOUTH OF THE COAST SHOULD PRODUCE A CLUSTER OF HEAVY
RAIN AND THUNDERSTORMS TOMORROW INTO TUESDAY NIGHT THAT MAINLY HUGS
THE COAST SOUTH OF THE ARKLAMISS. THERE SHOULD STILL BE SOME LIGHTER
RAINS THAT EVENTUALLY SPREAD NORTH THROUGH OUR AREA BY TOMORROW
EVENING DUE TO STRONG SYNOPTIC LIFTING MECHANISMS...BUT CONFIDENCE IS
FAIRLY HIGH THAT DRENCHING AND POTENTIALLY FLOODING RAINS WILL REMAIN
TO OUR SOUTH. IT IS POSSIBLE THAT A STRATIFORM RAIN SHIELD OF LONG
LASTING MODERATE RAIN (ANCHORED TO COASTAL CONVECTION) MAY BE ABLE TO
DEPOSIT 2 TO 3 INCHES OF RAIN OVER MY FAR SOUTHEAST ZONES LATE
TOMORROW THROUGH EARLY WEDNESDAY. WE WILL CONTINUE TO MENTION THE
POTENTIAL FOR THESE HEAVIER TOTALS IN SOUTHEAST MS IN THE HWO...BUT
GIVEN THE EXPECTATION OF NON-STELLAR RAIN RATES IT IS ANTICIPATED
THAT FLOODING WILL NOT BE A PROBLEM.
ELSEWHERE RAINFALL SHOULD NOT BE AT ALL HEAVY GIVEN STRONG MOISTURE
TRANSPORT BEING BLOCKED DOWN AT THE COAST. RAIN TOTALS OF UP TO ONE
INCH ARE NOT OUT OF THE QUESTION IN SOME SPORADIC AREAS LATER
TOMORROW THROUGH WEDNESDAY NIGHT...BUT THEY SHOULD GENERALLY BE
QUITE A BIT LESS THAN THAT. TEMPERATURES WILL HAVE A TOUGH TIME
RISING MUCH DURING THE DAY OVER THE NEXT 48 HOURS AS THE SYSTEM
GIVES US CLOUDS AND RAIN WHILE A SURFACE LOW PASSING THROUGH THE
HEART OF THE ARKLAMISS KEEPS WARM ADVECTION AT THE GROUND AIMED
MAINLY TO OUR EAST. THE BIGGEST QUESTION WITH REGARD TO TEMPS WILL
BE HOW COLD IT GETS WEDNESDAY NIGHT SINCE THERE IS MUCH UNCERTAINTY
WHETHER OR NOT WINDS WILL DIE DOWN AND CLOUDS WILL CLEAR OUT BEFORE
THURSDAY MORNING. RIGHT NOW I OPTED TO GO THE WARMER ROUTE...WHILE
REMAINING NEAR THE COOLER GFS MODEL FOR TEMPS UP TILL THAT POINT. AT
THIS MUCH THERE IS VERY HIGH CONFIDENCE THAT ANY PRECIP SQUEEZED OUT
ON THE BACKSIDE OF THE DEPARTING SURFACE LOW LATER WEDNESDAY IN OUR
REGION WILL "NON-WINTRY". /BB/
PORTION OF PREVIOUS LONG TERM...FOR THU-FRI NIGHT...MODELS ARE
SHOWING A COLDER SOLUTION AND THINGS LOOK TO GET QUITE CHILLY FOR
THE END OF THE WEEK INTO THE WEEKEND. THIS WILL BE A RESULT OF THE
DEEP CYCLONE WHICH WILL CARVE OUT A SUBSTANTIAL TROUGH OVER THE MID
SECTION OF THE CONUS. TO PUT THIS TROUGH INTO PERSPECTIVE...MID
LEVEL HEIGHT ANOMALIES WILL RUN SOME 3 TO 4 STANDARD DEV BELOW CLIMO
VALUES. ADDITIONALLY...850MB TEMPS WILL ALSO BE SOME 3 TO 4 NEG
STANDARD DEV WITH ACTUAL 850MB TEMPS RANGING FROM (-2C TO -8C). ALL
THAT SHOULD RESULT IN TEMPS SOME 10-15 DEGREES BELOW NORMAL VALUES
FOR EARLY DEC...IF NOT A BIT COLDER. THIS IS ALL SUPPORTED BY THE
EURO AS WELL AS THE GFS ENSEMBLE. AS A RESULT...I HAVE GONE QUITE A
BIT COLDER THAN THE PREV FORECAST AND SOMEWHAT COLDER THAN THE
LATEST GFS GUID WHICH ITSELF WAS COLDER.
LASTLY...THE GFS WAS WANTING TO RETURN MOISTURE BACK LATE SAT NIGHT
INTO SUN. I AM NOT READY TO JUMP ON THAT AS THE EURO IS DRY AS IT
KEEPS THE SFC HIGH OVER THE REGION ANOTHER 24-36 HRS. THE GFS
ENSEMBLE IS MORE IN LINE WITH THE EURO AND AS A RESULT...I HAVE CUT
POPS AND LOWERED TEMPS FOR THAT TIME FRAME. /CME/
&&
.AVIATION...
EARLY EVENING CONDITIONS GENERALLY VFR WITH SCATTERED MID-HIGH LEVEL
CLOUD LAYERS ABOVE 10K FEET. ONLY MVFR DECKS OVER SERN ZONES SHOULD
BE MOVING OUT BEFORE 04Z AS CLOUDS WILL CONTINUE TO SLOWLY DECREASE
FROM THE NW. GUSTY NNW WINDS HAVE DIMINISHED WITH SPEEDS BELOW 10 MPH
AT MOST SITES. PATCHY FOG WILL BE POSSIBLE TOWARD SUNRISE MAINLY NEAR
LAKES AND RIVER IN LOW LYING AREAS BUT VSBYS SHOULD REMAIN ABOVE 4SM AT
MOST LOCATIONS. HIGHER CLOUDS WILL INCREASE OVER THE FORECAST AREA
TUESDAY MORNING WITH CLOUD LAYERS STEADILY LOWERING WITH INCREASING
CHANCES OF RAIN TUESDAY AFTERNOON 20-24Z. MVFR CONDITIONS WILL RESUME
TUESDAY EVENING OVER MOST TAF SITES. /40/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 39 54 47 52 / 1 29 80 60
MERIDIAN 37 54 48 58 / 1 40 83 70
VICKSBURG 39 53 47 50 / 1 25 80 63
HATTIESBURG 42 53 52 57 / 4 89 99 52
NATCHEZ 42 53 48 51 / 4 44 87 50
GREENVILLE 35 51 45 49 / 0 12 80 82
GREENWOOD 36 55 45 50 / 0 15 71 81
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
