FXUS64 KJAN 252013
AFDJAN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
213 PM CST FRI DEC 25 2009
.DISCUSSION...SURFACE HIGH(1020MB) ALONG THE MIDDLE TX COAST WILL
BUILD NEWD ALONG THE GULF COAST TONIGHT IN THE WAKE OF OUR CHRISTMAS
EVE STORM SYSTEM NOW SPINNING THROUGH THE UPPER MS VALLEY. SATELLITE
VISIBLE IMAGES SHOWING A VERY NICE CLEARING OF THE CAA STRATOCU WAS
DEPARTING OUR NERN COUNTIES LEAVING ONLY SCATTERED THIN CIRRUS IN
PLACE. WLY SURFACE WINDS HAVE SLACKED UP TO GENERALLY LESS THAN 15
MPH AND HAVE TERMINATED THE LAKE WIND ADVY. DRY AIR SPREADING ACROSS
THE CWFA AND HAVE LOWERED DEWPOINTS A BIT MORE THAN GUIDANCE FORECASTS
AS THE HIGH PRESSURE PASSES SOUTH OF THE REGION.
LOW TEMPS SHOULD EASILY REACH M-U20S AS FLOW COMING STRAIGHT OFF THE
EXTENSIVE SNOW COVER OVER N TX/OK. OTHERWISE...THE WEAK SURFACE HIGH
SLIDES INTO NRN FL SATURDAY AFTERNOON ALLOWING OUR LOW LEVEL FLOW TO
BACK AROUND TO THE SW AS HIGHER LEVEL MOISTURE INCREASES MORE RAPIDLY.
HIGHS WILL ALSO BE A TAD WARMER SATURDAY AFTERNOON REACHING CLOSE TO
NORMS. ELEVATED UPGLIDE ON THE 315-325K CONTINUES THROUGH SATURDAY
NIGHT WITH SOME SPRINKLES/LIGHT RAIN POSSIBLY REACHING THE GROUND OVER
OUR SRN CWFA WELL AFTER MIDNIGHT WHEN TEMPS WILL BE REBOUNDING FROM
EARLIER LOWS JUST BELOW FREEZING. NAM HOLDS ALL RAINFALL GENERALLY S
OF THE COAST WHILE THE ECMWF WAS WETTER AND THE GFS WAS A SOLID
COMPROMISE OF THE TWO...SO THE MODEL OF CHOICE.
ON SUNDAY...A FRESH SURGE OF COLD AIR ARRIVES BY AFTERNOON WITH THE
PASSAGE OF A SHORTWAVE ROTATING AROUND THE GREAT LAKES UPPER LOW.
COLDER THAN NORMAL TEMPERATURES RETURN FOR THE START OF THE WEEK WITH
A 1030MB+ SURFACE HIGH MOVING OVER THE CENTRAL PLAINS SNOW FIELDS AND
INTO THE LOWER MS VALLEY BY LATE MONDAY. LOWS WILL GENERALLY BE BACK
INTO THE 20S AND HIGHS 45 TO 55 FROM SUNDAY NIGHT INTO TUESDAY.
SHORTWAVE RIDGING ALOFT IS EXPECTED TO DEVELOP OVER OUR REGION
TUESDAY TO ALLOW THE START OF SOME MODIFYING TEMPS BY WEDNESDAY.
HOWEVER...MOISTURE AND CLOUDS INCREASING FROM THE WEST TUESDAY
AFTERNOON COULD SHUT DOWN MUCH OF THE WARMING. BOTH THE GFS AND
ECMWF BRING PRECIPITATION BACK INTO OUR CWA TUESDAY NIGHT THROUGH
WEDNESDAY WITH QPF AMOUNTS OF ONE HALF TO ONE INCH. OBVIOUSLY...THE
TIMING OF THE PRECIPITATION AND JUST HOW MUCH TEMPS MODIFY WILL BE A
HUGE FACTOR TO OUR EVENTUAL OUTCOME. THE ECMWF IS STRONGER WITH THE
SHORTWAVE TROUGH THAN THE GFS AND DEVELOPS A SFC LOW FARTHER NORTH
OVER THE WESTERN GULF. WILL HAVE TO MONITOR THESE FACTORS CLOSELY
NEXT WEEK AS WE END 2009./40/
THE REST OF THE PREVIOUS DISCUSSION HINTS AT THE ISSUES AHEAD...
BOTH MODELS HAVE CRITICAL THICKNESSES JUST NORTH OF OUR AREA EARLY
WEDNESDAY AND WELL NORTH OF WHERE THE SIGNIFICANT RAINFALL IS
EXPECTED. AGAIN WL NOT INCLUDE MENTION OF WINTRY MIX PRECIPITATION
WITH THIS PACKAGE BUT FUTURE MODEL RUNS MAY END UP TRENDING COLDER.
BY WEDNESDAY NIGHT BOTH GFS AND ECMWF HAVE SFC LOWS JUST SOUTH OF OUR
CWA BUT WITH THE ECMWF BEING OVER SOUTHERN LOUISIANA AND THE GFS
SOUTH OVER THE NORTHERN GULF WATERS. THE RAIN WILL END FROM THE WEST
THURSDAY AS THE SFC LOW AND SHORTWAVE TROUGH SHIFT EAST. THE ECMWF
HAS A SIGNIFICANTLY LARGER AMPLITUDE UPPER LEVEL TROUGH OVER THE
CENTRAL CONUS FRIDAY AND IS MUCH COLDER OVER OUR REGION THAN THE GFS
BUT FRIDAY LOOKS DRY. /22/
&&
.AVIATION...MVFR CEILINGS WERE CONFINED TO PORTIONS OF THE NORTH AND
EAST FOR THIS AFTERNOON. THE CLOUDS WERE CLEARING FROM THE
SOUTHWEST. EXPECT ALL CEILINGS TO LIFT TO VFR CONDITIONS BY LATE
THIS AFTERNOON FROM THE SOUTHWEST. VFR CONDITIONS WILL THEN PREVAIL AT
ALL SITES FROM THIS EVENING AND THROUGH THE OVERNIGHT HOURS INTO
SATURDAY MORNING. GUSTY WEST TO SOUTHWEST WINDS WILL ALSO GRADUALLY
SUBSIDE BY THIS EVENING INTO THE OVERNIGHT HOURS AS THE STRONG LOW
PRESSURE SYSTEM LIFTS NORTHWARDS ALLOWING THIS TIGHT PRESSURE
GRADIENT OVER THE REGION TO FINALLY RELAX. /17/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 27 53 30 53 / 1 2 12 11
MERIDIAN 26 53 29 54 / 1 2 13 14
VICKSBURG 28 53 30 53 / 1 2 11 10
HATTIESBURG 26 55 33 55 / 2 3 23 21
NATCHEZ 28 53 32 54 / 1 1 17 11
GREENVILLE 31 50 29 49 / 1 3 9 8
GREENWOOD 30 52 28 49 / 1 3 9 10
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
