FXUS64 KJAN 071726 AAA
AFDJAN
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
1126 AM CST MON DEC 7 2009
.UPDATE...EVEN MORE COMPLEX FORECAST SITUATION DEVELOPING AS TIME
PASSES TODAY. FIRST STALLING FRONTAL BOUNDARY ALONG A KBTR-KMEI LINE
STARTING TO EVOLVE INTO A PROLIFIC FOG PRODUCER AS STEADIER RAINS
WANE ALONG IT. THIS BOUNDARY SHOULD REMAIN ABOUT IN PLACE THROUGH
EARLY TONIGHT BEFORE CREEPING NWWD SO HAVE ADDED FOG TO ALL ZONES.
EXPECT LINGERING LIGHT RAINS/DRIZZLE TO CONTINUE OVER MAINLY THE
SERN HALF OF THE CWFA THROUGH THE EVENING. TEMPERATURES WILL BE
HOLDING IN THE UPPER 40S TO MID 50S UNTIL BETTER WAA DEVELOPS AROUND
MIDNIGHT WHEN READINGS SHOULD BE CREEPING UPWARD ACROSS THE BOARD.
ALSO LOOK FOR THE NEXT ROUND OF RAINS TO BREAK OUT OVER THE WRN AND
NRN PORTIONS BECOMING HEAVY BEFORE MORNING. WILL CONSIDER A FLASH
FLOOD WATCH IN THE DELTA AREA FOR TUESDAY IN NEXT FORECAST PACKAGE.
THEN OUR WEATHER PICTURE FEATURES THE CLASH OF TWO OPPOSITE SEASON
AIR MASSES TUESDAY AND TUESDAY NIGHT. WARM FRONTOGENESIS DEVELOPING
ALONG THE GULF COAST WILL BE ATTEMPTING TO MOVE NWD UP THE LOWER MS
VALLEY WHILE A SURGING ARCTIC FRONT NOW CROSSING THE OZARKS SETTLES
SEWD. THIS SHALLOW COLD PUSH IS THE BIGGEST QUESTION MARK IN THE
FORECAST AS THE MODELS HAVE HAD MAJOR ISSUES DEALING WITH THESE
SITUATIONS IN THE PAST.
LATEST NAM12 HANDLING THE SHALLOW ARCTIC AIR BETTER AND DROPS THIS
AIR INTO OUR DELTA REGION TUESDAY MORNING WHICH COULD CREATE HAVOC
WITH THE NWD ADVANCEMENT OF VERY MOIST AND WARM AIR FROM THE GULF BY
TUESDAY AFTERNOON WHEN S WINDS COULD REACH 20-30MPH. CURRENT THINKING
IS THAT THE BOGUS HANDLING OF THE COLD AIR BY THE GFS WILL FORCE
RELIANCE ON THE NAM MORE THAN USUAL AND WE'LL COVER MORE ON THAT IN
THE AFTERNOON PACKAGE. CURRENT UPDATES TO ALL PRODUCTS SHOULD BE
ALREADY IN PLACE. STAY TUNED. /40/
&&
PORTIONS OF PREV DISCUSSION... /ISSUED 438 AM CST MON DEC 7 2009/
SHORT TERM...TODAY THROUGH TUESDAY NIGHT...RAIN CHANCES INCREASE
TONIGHT AHEAD OF ANOTHER APPROACHING SHORTWAVE. THIS WILL INCREASE
MOISTURE CONVERGENCE AT 850MB WITH +330K THETA E AIR NOSING INTO OUR
SOUTHWEST BY MIDNIGHT. A LITTLE MORE INSTABILITY IS EXPECTED WITH
THIS SYSTEM AND ELEVATED THUNDERSTORMS WILL BECOME POSSIBLE BY 12Z
TUESDAY. OUR PW WILL BE BACK TO AN INCH AND A HALF CONTRIBUTING TO
LOCALLY HEAVY RAINFALL POTENTIAL. WL CONTINUE TO MONITOR THIS TIME
FRAME FOR FLOODING POTENTIAL TODAY. WAA WILL INCREASE SIGNIFICANTLY
OVER OUR REGION AS WELL TUESDAY AHEAD OF THE POTENT MID LEVEL
SHORTWAVE TROUGH THAT IS DROPPING INTO CALIFORNIA THIS MORNING. THIS
POTENT SHORTWAVE WILL HELP DEEPEN A SURFACE LOW AS THAT IS EXPECTED
TO MOVE FROM THE FOUR CORNERS REGION EARLY TUESDAY MORNING TO THE MID
MISSISSIPPI RIVER VALLEY TUESDAY NIGHT. BY TUESDAY AFTERNOON DEEP
LAYER SHEAR IS EXPECTED TO HAVE INCREASED TO 45-60KTS WITH 0-1KM
SHEAR AROUND 40KTS OVER OUR AREA. PWS SHOULD BE BACK ABOVE AN INCH
AND A HALF WITH MID 60 DEW POINTS RISING THROUGH THE 60S. AFTERNOON
TEMPERATURES MAY CLIMB INTO THE LOWER 70S ACROSS THE SOUTHERN HALF OF
THE AREA. DESPITE THE INCREASE IN DEEP LAYER MOISTURE AND DEEP LAYER
SHEAR...INSTABILITY LOOKS TO REMAIN SOMEWHAT LIMITED WITH WEAK LAPSE
RATES AND MLCAPES AROUND 500J/KG BUT SUFFICIENT FOR SEVERE
THUNDERSTORM DEVELOPMENT. SPC HAS OUTLOOKED OUR AREA WITH A SLIGHT
RISK AND WL CONTINUE MENTION IN THE HWO. DAMAGING WINDS AND A FEW
TORNADOES LOOK TO BE THE MAIN THREATS. LATEST MODEL RUNS APPEAR
FASTER IN ENDING THE RAIN FROM THE WEST TUESDAY NIGHT WITH THE STRONG
COLD FRONT RACING THROUGH OUR AREA WEDNESDAY. STRONG GUSTY WINDS ARE
EXPECTED AHEAD AND BEHIND THIS SYSTEM WARRANTING A LAKE WIND ADVISORY
AT SOME POINT. /22/
&&
.AVIATION...LIGHT RAIN IS OCCURRING ACROSS MUCH OF THE AREA THIS
MORNING...BUT IS BEGINNING TO END FROM WEST TO EAST. MOST OF THE RAIN
WILL SHIFT TO THE EAST OF THE AREA BY MID AFTERNOON...BUT MVFR/IFR
CEILINGS AND OCCASIONAL LIGHT RAIN WILL CONTINUE. INSTABILITY WILL
REMAIN LIMITED TODAY AND NO THUNDER IS EXPECTED. RAIN WILL INCREASE
TONIGHT FROM THE SOUTHWEST WITH LOWERING CEILINGS AND VISIBILITIES.
THUNDERSTORMS WILL ALSO BE POSSIBLE IN THE WEST BY 12Z. /15/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 53 52 72 53 / 60 87 100 88
MERIDIAN 53 49 69 54 / 59 74 100 89
VICKSBURG 54 52 71 53 / 58 97 100 75
HATTIESBURG 57 53 72 59 / 65 60 90 87
NATCHEZ 56 55 75 54 / 63 98 100 79
GREENVILLE 51 46 63 48 / 55 98 100 63
GREENWOOD 51 46 63 51 / 56 91 100 78
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
