FXUS64 KJAN 160302
AFDJAN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
835 PM CST TUE DEC 15 2009
.UPDATE...LATEST SURFACE ANALYSIS HAS HIGH PRESSURE CENTERED OVER
THE MID MISSISSIPPI VALLEY THAT IS MOVING COLDER AND DRIER AIR INTO
OUR AREA FROM THE NORTH. THIS HAS HELPED DISSIPATE THE LOWER CLOUD
COVER IN OUR NORTH BUT SATELLITE IMAGERY/RUC ANALYSIS SHOWS THE
TROUGH OVER TEXAS CONTINUING TO DRAW UP MOISTURE AND THICK HIGH
CLOUDS ACROSS OUR WHOLE CWA. THIS CLOUD COVER HAS HELD TEMPERATURES
UP IN THE SOUTH MORE THAN EXPECTED ALREADY. THE HIGH CLOUDS LOOK TO
HOLD IN MUCH LONGER THAN PREVIOUS FORECAST SUGGESTED. HAVE SLOWED
CLEARING FROM WEST AND RAISED OVERNIGHT LOWS ACROSS THE SOUTHEAST
HALF OF THE AREA TONIGHT. NEAR FREEZING TEMPERATURES ARE STILL
EXPECTED IN THE NORTH BY MORNING. WINDS HAVE BECOME LIGHTER THIS
EVENING BUT WILL STAY UP ALL NIGHT SO FOG DEVELOPMENT IS NOT
EXPECTED. UPDATES ARE OUT. /22/
&&
.AVIATION...UPDATED...HIGH PRESSURE TO THE NORTH WILL STRENGTHEN
OVER OUR AREA AND CONTINUE TO ERODE THE LOW CLOUD COVER FROM THE
NORTH. CEILINGS HAVE IMPROVED ACROSS THE NORTHERN THIRD OF THE AREA
BUT WAS STILL HOLDING ON ALONG THE INTERSTATE 20 CORRIDOR AND SOUTH.
MVFR CEILINGS AROUND 1500FT WERE BEING OBSERVED AND WILL CONTINUE
OVER THE SOUTHERN HALF THROUGH 06Z BEFORE DISSIPATING BY 09Z. VFR
CONDITIONS WILL THEN PREVAIL AREAWIDE ALTHOUGH PLENTY OF HIGH CLOUDS
WILL CONTINUE TO MOVE TO THE NORTHEAST ACROSS THE REGION TONIGHT AS
A MID LEVEL TROUGH LINGERS OVER THE SOUTHERN PLAINS. VFR CONDITIONS
EXPECTED WEDNESDAY. /22/
&&
.PREV DISCUSSION... /ISSUED 329 PM CST TUE DEC 15 2009/
SHORT TERM...THE RISK OF FLOODING HAS ENDED FOR THE ARKLAMISS IN
THE WAKE OF THE COLD FRONT THAT HAS EXITED THE REGION. THE LAKE WIND
ADVISORY HAS BEEN ALLOWED TO EXPIRE AS WIND SPEEDS WILL GRADUALLY
WEAKEN AS SUNSET APPROACHES.
RADAR RAINFALL ESTIMATES SHOW VALUES FROM 3-4 INCHES AT MANY
LOCATIONS ALONG AND SOUTH OF HIGHWAY 84 WITH LOCALIZED VALUES FROM
5-6 INCHES. RAINFALL CONTINUES TO END FROM THE NW WITH ONLY LIGHT
PRECIP OVER SOME SRN ZONES. RAIN WILL END AT ALL LOCATIONS AROUND
SUNSET. THE FORECAST EMPHASIS WILL SHIFT FROM RAINFALL TO
TEMPERATURES FOR TONIGHT. THE COLDER AIR MASS THAT HAS PUSHED INTO
THE AREA WILL RESULT IN OVERNIGHT LOWS IN THE 30S ACROSS THE MOST OF
THE REGION. THE DEGREE OF COOLING WILL BE HAMPERED BY A HEALTHY
SURFACE PRESSURE GRADIENT THAT WILL PERSIST THROUGH MUCH OF THE
NIGHT. THE FORECAST WILL FOLLOW SLIGHTLY COOLER NAM TEMPS...WHICH
DROP LOWS TO THE FREEZING MARK OVER NRN ZONES AND LOWER 30S AS FAR S
AS THE I-20 CORRIDOR. SURFACE RIDGING THAT MOVES THIS WAY IN THE
WAKE OF THE COLD FRONT WILL REMAIN CENTERED TO THE N OF THE
ARKLAMISS REGION BUT LOW LEVEL COLD AIR ADVECTION LOOKS STRONG
ENOUGH TO KEEP WED AFTERNOON HIGHS A LITTLE COOLER THAN ADVERTISED
BY MOS TODAY SO WILL STICK WITH COOLER NUMBERS POSTED BY THE
PREVIOUS FORECAST CREW. NW WINDS WILL BE BREEZY TOMORROW... ALTHOUGH
A BIT LIGHTER THAN TODAY...CONTRIBUTING TO SLIGHTLY COOLER TEMPS FOR
TOMORROW.
THE GFS HAS TAKEN A MUCH WETTER DIRECTION OVER THE PAST 24
HOURS...INDICATING LIKELY POPS FOR SRN ZONES BY THURSDAY NIGHT AS
THE NEXT SURFACE LOW TRACKS ACROSS THE NRN GULF. THE MODELS ARE NOW
FOLLOWING THE LEAD OF THE WETTER EURO...PIVOTING A SHORTWAVE FROM
THE TEX/MEX BORDER REGION ACROSS THE WRN AND CENTRAL GULF COAST AREA
LATE THURSDAY INTO FRIDAY. HAVE INCREASED POPS OVER SRN ZONES PER
LATEST MOS GUIDANCE FOR SRN ZONES AND ADDED A SLIGHT CHANCE OF RAIN
AS FAR N AS THE I-20 CORRIDOR FOR THURSDAY AFTERNOON. MODELS
SOLUTIONS DIVERGE TO A GREATER DEGREE FOR THURSDAY NIGHT INTO
FRIDAY. WILL LEAVE CHANCE POPS ACROSS CENTRAL ZONES WHICH WILL FALL
BETWEEN WETTER GFS AND DRIER NAM BUT INCREASED POPS TO LIKELY FOR
THE SOUTH WHERE MODEL AGREEMENT IS BETTER. CAPE VALUES ARE FORECAST
TO REMAIN VERY LOW AND PRECIPITABLE WATER NEAR 1 INCH OVER SRN
AREAS.
HAVE MADE NO CHANGES ANY FARTHER INTO THE EXTENDED BUT THE LATEST
MODELS CONTINUE TO SHOW A PARTICULARLY COLD PATTERN SETTING UP FOR
THE WEEKEND INTO EARLY NEXT WEEK.
PREV DISCUSSION: FRI NIGHT THROUGH MONDAY...A MOSTLY DRY AND COLDER
WEATHER REGIME IS FORECAST FOR THE WEEKEND INTO EARLY CHRISTMAS WEEK
AS STRONG UPPER LEVEL TROUGH DEVELOPS OVER THE EASTERN CONUS.
CONFIDENCE HAS INCREASED IN THE FORECAST FOR THE LONGER RANGE
PERIODS WITH THE 00Z GFS AND 00Z GFS ENSEMBLE MEAN NOW IN GREAT
AGREEMENT. AND THE 00Z ECMWF SHOWS ENOUGH AGREEMENT SO THAT WE HAVE
GENERALLY FOLLOWED THE GFS FOR FORECAST DETAILS.
AMPLIFICATION OF THE WESTERN RIDGE/EASTERN TROUGH PATTERN WILL
RESULT IN FAIRLY STRONG COLD ADVECTION SATURDAY AND SATURDAY NIGHT.
MODELS HAVE HINTED THAT A WEAK MID LEVEL TROUGH IN THE NORTHWEST
FLOW PATTERN COULD INDUCE VERY LIGHT PRECIPITATION OVER THE LOWER MS
VALLEY REGION AT SOME POINT FROM SATURDAY INTO SUNDAY. WITH THE
COLDER AIR MOVING IN AND LOW LEVEL INSTABILITY...BLUSTERY CONDITIONS
ALONG WITH A MIX OF SPRINKLES AND LIGHT SNOW SHOWERS/FLURRIES WILL
BE POSSIBLE...MOST LIKELY SATURDAY NIGHT. THIS WILL BE FOLLOWED BY
CHILLY AND DRY WEATHER FOR THE SUNDAY-MONDAY PERIOD WITH TEMPERATURES
10 DEGREES BELOW CLIMATIC AVERAGE. THE FORECASTED PATTERN SUGGESTS
THERE COULD BE A DAY OR NIGHT WHICH HAVE COLDER TEMPERATURES...BUT
THE FORECAST DETAILS ARE TOO DIFFICULT TO PIN DOWN AT THIS RANGE.
/EC/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 33 51 34 52 / 0 0 6 15
MERIDIAN 34 52 31 53 / 0 0 6 15
VICKSBURG 34 51 35 51 / 0 0 6 15
HATTIESBURG 38 57 35 54 / 7 0 6 36
NATCHEZ 36 51 37 52 / 7 0 8 30
GREENVILLE 32 47 33 51 / 0 0 5 5
GREENWOOD 31 51 33 52 / 0 0 5 5
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
22/03/EC
