FXUS64 KJAN 282114
AFDJAN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON MS
314 PM CST SAT NOV 28 2009
.DISCUSSION...TONIGHT THROUGH SUNDAY NIGHT...HIGH PRESSURE WILL
CONTINUE TO SLIDE EAST OF THE FORECAST AREA TONIGHT ALLOWING MID AND
LOW LEVEL WINDS TO BECOME MORE SOUTHERLY. THE COMBINATION OF DECENT
ISENTROPIC UPGLIDE AND A STORM SYSTEM APPROACHING THE LOWER
MISSISSIPPI RIVER VALLEY FROM THE WEST THROUGH THE DAY SUNDAY WILL
KEEP SOME CLOUDS OVER THE CWA THROUGH THE OVERNIGHT HOURS. THIS
WILL ALL RESULT IN A SLIGHTLY MILDER NIGHT...COMPARED TO PREVIOUS
NIGHT...ACROSS THE FORECAST AREA TONIGHT AS TEMPERATURES RANGE FROM
THE UPPER 40S WEST OF THE MISSISSIPPI RIVER TO AROUND 40 ACROSS EAST
MISSISSIPPI.
RAIN CHANCES WILL BE ON THE INCREASE THROUGH THE DAY SUNDAY AS AN
UPPER LEVEL TROUGH DROPS SOUTHEAST OUT OF THE NORTHERN PLAINS...
ACROSS THE MID MISSISSIPPI RIVER VALLEY...AND TOWARDS THE SOUTHEAST
UNITED STATES. THIS SYSTEM WILL DRAG A COLD FRONT INTO AND
EVENTUALLY THROUGH THE FORECAST AREA LATE SUNDAY NIGHT INTO MONDAY
MORNING. GOOD ISENTROPIC UPGLIDE AHEAD OF THE FRONT THOUGH COULD
CAUSE SOME LIGHT RAIN TO DEVELOP ACROSS MAINLY WESTERN PORTIONS OF
THE AREA AS EARLY AS SUNDAY AFTERNOON. THE BETTER RAIN CHANCES
HOWEVER WILL EXIST AREA WIDE SUNDAY NIGHT INTO MONDAY MORNING AS THE
FRONT MOVES ACROSS THE FORECAST AREA.
THE PREVIOUS LONG TERM FORECAST DISCUSSION FOLLOWS. /19/
MONDAY THROUGH NEXT SATURDAY...COLD FRONT TRAVERSING THE REGION
MONDAY WILL CONTINUE TO SLIDE TO THE SOUTHEAST THROUGH THE MORNING
HOURS AND EXIT THE CWA IN THE AFTERNOON. NORTHERLY WINDS WILL
INCREASE BEHIND THE FRONT AND WILL LIKELY NEED A LAKE WIND ADVISORY
FOR AREA LAKES AFTER FROPA. MEX POPS LOOKED GOOD MON KEEPING LIKELY
WORDING FOR MOST OF THE AREA AND A CHANCE OF RAIN FOR THE
NORTHWESTERN TIER COUNTIES. LOW LEVEL WARM/MOIST ADVECTION AHEAD OF
THE FRONT STRUGGLES TO DEVELOP ANY SIGNIFICANT INSTABILITY DUE TO
THE DRY BL CONDITIONS PRESENT ALONG THE GULF COAST...AS WELL AS OVER
THE NORTHERN GULF AND WILL MAINTAIN ZERO THUNDER CHANCES IN THE
FORECAST THROUGH MONDAY.
FROM HERE THE FORECAST CONCERN IS CENTERED ON SFC LOW PRESSURE IN
THE WESTERN GULF DEVELOPING MONDAY NIGHT ALONG THE FRONTAL
BOUNDARY...AHEAD OF AN APPROACHING SRN STREAM S/WV...AND THE
ASSOCIATED HEAVY RAIN AND THUNDER CHANCES FOR THE ARKLAMISS THROUGH
WEDNESDAY. GFS/ECMWF/GEFS ARE IN DECENT AGREEMENT WITH THE
DEVELOPMENT OF THE LOW LATE MONDAY OUT OVER THE WESTERN GULF. FROM
HERE THE GUIDANCE DIFFERS A BIT AS THE GFS/00Z OUTRUNS ITS ENSEMBLE
MEAN AS WELL AS THE ECMWF/00Z WITH THE PROGRESSION OF THIS SYSTEM.
GFS ADVANCES THE UPPER LOW INTO CENTRAL LA BY 12Z WED...WITH THE
ECMWF KEEPING THE UPPER LOW BACK OVER THE FORT WORTH AREA 12Z WED.
THE GEFS SHOWS MORE SUPPORT FOR THE ECMWF SOLUTION MAKING FOR LOWER
CONFIDENCE IN THE GFS. FOR NOW...WILL GRADUALLY REINTRODUCE POPS
MONDAY NIGHT BUT NOT QUITE AS FAST AS GFS SUGGESTS BASED ON THE
PREFERRED SLOWER SOLUTION. RAIN CHANCES WILL CONTINUE INCREASING FROM
SOUTH TO NORTH THROUGH THE DAY TUESDAY AS THE SFC LOW TRACKS TOWARD
THE GULF COAST. HAVE INTRODUCED SOME THUNDER CHANCES STARTING OVER
WESTERN AREAS TUESDAY NIGHT AS WARM/MOIST AIR IS LIFTED OVER THE BL
AHEAD OF THE LOW(MODELS INDICATE A SWATH OF 200-400J/KG MUCAPE
SLIDING ACROSS NORTHERN AREAS)...COMBINED WITH APPROACHING DEEP LAYER
LIFT/STRENGTHENING JET SUPPORT IN ADVANCE OF THE UPPER S/WV. WILL
KEEP THUNDER CHANCES ACROSS NORTHERN AND EVENTUALLY NORTHEASTERN
ZONES THROUGH THE MORNING HOURS WEDNESDAY BEFORE COOL/DRY ADVECTION
DEVELOPS ACROSS THE ARKLAMISS IN WAKE OF THE LOW THAT HAS NOW PASSED
EAST OF THE AREA. ONE ITEM OF NOTE IS THE DISCREPANCY BETWEEN THE
GFS/ECMWF WITH REGARDS TO RAIN TOTALS WITH THIS SYSTEM. THE MORE
PROGRESSIVE GFS POSITIONS A SWATH OF 4 TO 6IN OF RAIN WELL EAST OF
OUR CWA WHILE THE ECMWF/00Z SHOWS A SWATH OF 4 TO 5IN FALLING OVER
FAR SOUTHEASTERN AREAS OF THE ARKLAMISS BY 12Z WED. CONSIDERING THE
UNCERTAINTY IN THE TRACK OF THE LOW AT THIS POINT WILL FORGO MENTION
OF HEAVY RAIN IN THE HWO. THIS WILL BE MONITORED AS THE SITUATION
EVOLVES.
RAIN CHANCES WILL TAPER OFF WEDNESDAY AFTERNOON INTO THE EVENING AS
THE LOW MOVES EAST BUT DID NOT DECREASE RAIN CHANCES QUITE AS FAST
AS THE GFS SUGGESTS WITH SLIGHT CHANCE POPS CARRIED OVER
NORTHEASTERN ZONES INTO WEDNESDAY EVENING. FROM HERE MODELS
GENERALLY AGREE COLD HIGH PRESSURE WILL SETTLE OVER THE REGION FOR
THE REMAINDER OF THE WEEK KEEPING RAIN CHANCES OUT...AND BELOW
NORMAL TEMPS IN THE FORECAST THROUGH SATURDAY.
MEX TEMPS LOOKED REASONABLE THROUGH THE PERIOD ALTHOUGH SOME
ADJUSTMENTS TOWARD MEN GUID WERE MADE LATE IN THE WEEK. /BK/
&&
.AVIATION...HIGH PRESSURE HAS SHIFTED TO THE EAST OF THE AREA TODAY
AND THIS HAS ALLOWED SOME INCREASE IN MOISTURE ACROSS THE ARKLAMISS.
VFR CONDITIONS WILL CONTINUE THROUGH THE PERIOD WITH MAINLY AN
INCREASE OF MID/HIGH CLOUDS OUT AHEAD OF A DEVELOPING STORM SYSTEM.
THE WINDS WILL REMAIN LIGHT OUT OF THE SOUTH THROUGH THE PERIOD./15/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 46 68 52 57 / 1 21 48 59
MERIDIAN 39 68 50 59 / 0 13 35 56
VICKSBURG 48 69 52 55 / 5 32 58 60
HATTIESBURG 43 71 52 65 / 1 7 16 53
NATCHEZ 49 70 55 57 / 5 20 45 67
GREENVILLE 48 64 49 54 / 5 52 79 43
GREENWOOD 45 65 49 54 / 3 45 72 45
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
19/15
