FXUS64 KJAN 091559
AFDJAN
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
955 AM CST WED DEC 9 2009
.UPDATE...LATEST SATELLITE IMAGERY SHOWED A BROAD UPPER TROUGH OVER
THE CONUS. A STRONG UPPER JET WAS HELPING TO BRING A SURGE OF
CANADIAN AIR INTO THE REGION. IR/VIS IMAGERY SHOWS SOME PATCHY HIGH
CLOUDS APPROACHING THE REGION FROM THE PLAINS. THE CENTER OF THE
CANADIAN HIGH WAS NOTED ACROSS THE SOUTHERN PLAINS. A SECONDARY
SURGE OF COOL CANADIAN AIR WAS MAKING ITS WAY INTO THE ARKLAMISS
THIS MORNING...BEHIND A COLD FRONT THAT MOVED THROUGH THE REGION
OVERNIGHT. THIS WILL HELP TEMPS TO GRADUALLY FALL ACROSS THE REGION
DURING THE AFTERNOON. TEMPS WILL HOLD STEADY IN THE SOUTHEAST UNTIL
MID TO LATE AFTERNOON. SO EXPECT TEMPS TO GRADUALLY FALL FROM THE
50S AND 60S TO MAINLY THE 40S AND 50S BY LATE THIS AFTERNOON AS
STRONG COLD AIR ADVECTION PUSHES ACROSS THE REGION. THE STRONG
PRESSURE GRADIENT WITH THIS SYSTEM WILL KEEP WINDS UP TO LAKE WIND
ADVISORY LEVELS REGION WIDE UNTIL ABOUT MID AFTERNOON. SO WITH THAT
SAID...CURRENT FORECAST PARAMETERS APPEAR TO BE ON TRACK./17/
&&
.PREV DISCUSSION... /ISSUED 500 AM CST WED DEC 9 2009/
SHORT TERM...TODAY THROUGH THURSDAY NIGHT...THE INITIAL COLD FRONT
IS SOUTH OF A MERIDIAN TO BROOKHAVEN LINE WITH A VERY NARROW BAND OF
SHOWERS ALONG IT. ALTHOUGH THIS FRONT WILL SHIFT SOUTH OF OUR AREA
BY SUNRISE AND BRING AN END TO THE RAIN....A STRONGER REINFORCING
PUNCH OF COOL DRY AIR WITH A NW WIND SHIFT WAS MAKING ITS WAY ACROSS
CENTRAL ARKANSAS AND WILL MOVE ACROSS OUR CWA TODAY. THIS
REINFORCING COLD FRONT WILL DROP TEMPERATURES THROUGH THE DAY AS IT
MOVES THROUGH. THUS...HIGHS FOR TODAY OCCURRED AT MIDNIGHT FOR MOST
OF THE AREA. 4 AM TEMPERATURES SOUTH OF THE INITIAL COLD FRONT WERE
STILL RUNNING IN THE UPPER 60S TO LOWER 70S. HATTIESBURG WAS OUR
WARM SPOT AT 72F. HAVE GONE CONSIDERABLY WARMER THAN GUIDANCE TODAY
ON MAX TEMPS TO ACCOUNT FOR THE EARLIER WARMER TEMPS. THE INTENSE
SFC LOW WAS LOCATED OVER NORTHERN ILLINOIS BUT THE PRESSURE GRADIENT
ASSOCIATED WITH THE LOW WAS STILL RESULTING IN GUSTS ACROSS OUR
AREA. AS THE NEXT FRONT MOVES THROUGH STRONG GUSTY NORTHWEST WINDS
WILL MEET AND EXCEED LOCAL LAKE WIND ADVISORY CRITERIA AND WL
MAINTAIN THE LAKE ADVISORY THROUGH MID AFTERNOON. STRONGEST WIND
GUSTS WILL BE OVER OUR AREA LAKES. MODELS DO INDICATE A WEAKENING OF
THE PRESSURE GRADIENT AND LIGHTER WINDS BY MIS AFTERNOON.
ALTHOUGH THE DEEP LOW PRESSURE SYSTEM THAT BROUGHT US SOME SEVERE
WEATHER TUESDAY WILL LIFT UP INTO CANADA TONIGHT...A BROAD UPPER
LEVEL TROUGH WILL REMAIN OVER MOST OF THE CONUS MAINTAINING A WEST
TO NORTHWEST FLOW OVER OUR REGION. AT THE SURFACE HIGH PRESSURE WILL
MOVE OVER OUR AREA FROM THE NW TODAY AND SHIFT EAST OF OUR AREA
FRIDAY. TOGETHER THIS WILL RESULT IN COOL DRY WEATHER FOR US INTO
FRIDAY. TONIGHT WILL BE RATHER COLD AGAIN. HIGH PRESSURE WILL BE TO
OUR NW AND MAINTAIN A LIGHT NW WIND ACROSS THE AREA. MOST OF THE
AREA WILL BOTTOM OUT AT OR BELOW FREEZING. CONSIDERING THE RECENT
RAINFALL AND WIND WENT CLOSER TOWARD THE WARMER GFS OVERNIGHT LOWS
VERSUS THE NAM. THE COOLER THAN NORMAL CONDITIONS WILL CONTINUE
THURSDAY DESPITE NEARLY FULL INSOLATION. THE SOUTH MAY CLIMB INTO
THE LOWER 50S BUT MOST OF THE AREA WILL ONLY WARM INTO THE 40S. THE
SURFACE HIGH WILL BEGIN SHIFTING EAST THURSDAY NIGHT AND MAY RESULT
IN LIGHT RETURN FLOW IN THE WEST HOLDING UP MINIMUM TEMPERATURES
THERE BUT THE REST OF THE AREA MAY SEE THE COLDEST NIGHT OF THE
FORECAST PERIOD. THE EAST IS EXPECTED TO BOTTOM OUR IN THE MID 20S.
GUIDANCE TEMPS WERE CLOSE THURSDAY AND THURSDAY NIGHT AND THE MAV
WAS GENERALLY ACCEPTED. /22/
LONG TERM...FRIDAY THROUGH WEDNESDAY...AFTER THE COOL DRY START IN
THE SHORT TERM WL SEE A RETURN TO WARMER AND WETTER WEATHER FOR MOST
OF THE LONG TERM. THE MODELS ARE A LITTLE SLOWER IN MOVING
PRECIPITATION BACK INTO OUR AREA FRIDAY SO WL HAVE A CHANCE TO WARM
UP BEFORE SEEING ANY PRECIPITATION. FRIDAY OUR WINDS ALOFT WILL BACK
TO SOUTHWESTERLY AS THE SFC HIGH TO THE EAST MOVES TO THE MID
ATLANTIC SEABOARD. A WEAK DISTURBANCE IN THE SOUTHWEST FLOW ALOFT
WILL HELP DEVELOP A SURFACE LOW OVER THE WESTERN GULF. THIS WILL
RESULT IN ISENTROPIC LIFT INCREASING OVER OUR REGION AND RAIN
DEVELOPMENT FROM THE SOUTH FRIDAY. IT WILL LIKELY TAKE MOST OF THE
DAY TO MOISTEN UP AND THE 00Z GFS IS NOW FASTER THAN THE ECMWF/NAM
AND SREF IN BRINGING LIGHT RAIN INTO OUR SOUTHERN ZONES BUT NOT
UNTIL THE AFTERNOON. LIGHT RAIN IS EXPECTED TO THE HIGHWAY 84
CORRIDOR BY EVENING. THIS RAIN AREA WILL SPREAD NORTH THROUGH FRIDAY
NIGHT AND LAST INTO SATURDAY EVENING. DRIER WEATHER IS INDICATED FOR
SUNDAY BUT ANOTHER WAVE IS EXPECTED TO BRING RAIN ON MONDAY. A
STRONGER SHORTWAVE IS EXPECTED TO MOVE OVER THE SOUTHERN PLAINS
MONDAY AND HELP DEVELOP A SFC LOW THAT IS PROGGED TO MOVE ACROSS OUR
CWA MONDAY NIGHT. RAIN CHANCES WILL INCREASE LATE SUNDAY NIGHT AHEAD
OF THE THIS SYSTEM AND LAST THROUGH MONDAY. BOTH GFS AND ECMWF SHOW
A STRONG COLD FRONT DROPPING INTO OUR REGION TUESDAY MORNING WITH
COLDER AND DRIER WEATHER SLATED FOR WEDNESDAY. /22/
&&
.AVIATION...THE COLD FRONT HAS PUSHED SOUTHEAST OF THE REGION...WHILE
A SECONDARY SURGE OF COOL AIR MAKES IT ACROSS THE REGION DURING THE
DAY. THE PRESSURE GRADIENT ASSOCIATED WITH THIS SYSTEM WILL BRING
BREEZY CONDITIONS ACROSS THE REGION WITH GUSTS OF AROUND 30 MPH. IT
WILL BE A BUMPY RIDE AVIATION WISE WITH THE WIND GUSTS. SCATTERED
CLOUDS WITH BASES AROUND 3000 FT COULD IMPACT LOCATIONS ALONG AND
NORTH OF INTERSTATE 20 THIS AFTERNOON... WITH A FEW HIGH CLOUDS
STREAMING ACROSS THE REGION THIS AFTERNOON INTO THURSDAY MORNING.
OTHERWISE VFR CONDITIONS WILL PREVAIL THROUGH TONIGHT AS SURFACE WINDS
DECREASE BY SUNSET. EXPECT LIGHT NORTH WINDS OVERNIGHT NEAR THE
SURFACE./17/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 58 30 48 30 / 0 2 3 5
MERIDIAN 66 31 48 27 / 0 3 3 5
VICKSBURG 55 30 48 31 / 0 1 3 5
HATTIESBURG 68 33 50 31 / 0 4 3 8
NATCHEZ 59 29 49 33 / 0 3 3 9
GREENVILLE 48 28 45 29 / 0 0 3 5
GREENWOOD 51 27 45 28 / 0 0 3 5
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...LAKE WIND ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR MSZ018-019-
025>066-072>074.
LA...LAKE WIND ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR LAZ007>009-
015-016-023>026.
AR...LAKE WIND ADVISORY UNTIL 3 PM CST THIS AFTERNOON FOR ARZ074-075.
&&
$$
