FXUS64 KJAN 261604 AAA
AFDJAN
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON MS
1004 AM CST SAT DEC 26 2009
.UPDATE...FORECAST IS ON TRACK THIS MORNING WITH NO UPDATES NEEDED
OTHER THAN SLIGHT ADJUSTMENTS TO HOURLY TEMPS BASED ON LATEST
TRENDS. PREVIOUS DISCUSSION IS BELOW. /BK/
&&
.SHORT TERM...TODAY THROUGH SUNDAY NIGHT...COLDER THAN NORMAL AND
DRY FOR MOST OF THE AREA THROUGH THE SHORT TERM. THE LARGE NEARLY
STACKED LOW WILL CONTINUE MOVING OVER THE WESTERN GREAT LAKES REGION
TODAY MAINTAINING SOUTHWEST FLOW ALOFT OVER OUR REGION. AT THE
SURFACE HIGH PRESSURE THAT WAS NOTED CENTERED OVER THE SOUTHERN HALF
OF OUR AREA THIS MORNING WILL MOVE SLOWLY TO THE EAST. THE SOUTHWEST
FLOW ALOFT WILL BRING SOME HIGH THIN CLOUDS TO THE SOUTHERN PORTIONS
OF THE AREA TODAY BUT MOSTLY SUNNY SKIES ARE EXPECTED. THE SFC HIGH
WILL HELP PROVIDE MUCH LIGHTER WINDS OVER OUR AREA TODAY AND ALLOW
FOR WARMER TEMPERATURES. AFTERNOON HIGHS WILL BE NEARLY TEN DEGREES
WARMER IN THE NORTH THAN ON FRIDAY AS MOST OF THE AREA REACHES THE
LOWER 50S. A WEAK DISTURBANCE IN THE SOUTHWEST FLOW ALOFT WILL HELP
DEVELOP A SURFACE LOW TONIGHT OVER THE WESTERN GULF THAT WILL MOVE
TO THE EAST THROUGH SUNDAY. THE GFS/SREF AND NAM HOLD MOST OF THE
SIGNIFICANT PRECIPITATION ASSOCIATED WITH THE LOW JUST SOUTH OF OUR
AREA WHILE THE ECMWF CONTINUES TO BRING SOME LIGHT RAIN TO OUR
SOUTHERN MOST COUNTIES AND PARISHES AFTER MIDNIGHT. WL ACCOUNT FOR
THIS AND MENTION SLIGHT CHANCE OF LIGHT RAIN AFTER MIDNIGHT AND OUR
SOUTH AND TAPER OFF TO A FEW SPRINKLES IN THE SOUTHEAST MOST
COUNTIES EARLY SUNDAY MORNING. IT WILL BE QUITE COLD FOR THE
NORTHERN HALF OF OUR AREA AGAIN TONIGHT AS SUNDAY MORNING LOWS DIP
BACK INTO THE 20S. SURFACE TEMPERATURES IN THE SOUTH SHOULD REMAIN
ABOVE FREEZING AND MODEL SOUNDINGS SUGGEST A WARM ENOUGH LAYER ALOFT
FOR ONLY A COLD RAIN SHOULD ANY REACH THE GROUND IN OUR SOUTH
TONIGHT. ANOTHER SHORT WAVE WILL BE ROUNDING THE BASE OF THE LARGE
UPPER LOW TO OUR NORTH SUNDAY AND BRING OUR REGION A REINFORCING
SHOT OF COOLER AIR. THE COOLER AIR MAY NOT ARRIVE IN OUR SOUTHEAST
UNTIL LATE AFTERNOON BUT IN THE NORTH AFTERNOON HIGHS SHOULD TOP OUT
SEVERAL DEGREES LOWER THAN TODAY. ALTHOUGH WITH THE SOUTHERN BRANCH
OF THE JET STREAM REMAINING OVERHEAD SUNDAY NIGHT A FEW MID TO HIGH
LEVEL CLOUDS WILL BE POSSIBLE...BUT SHOULD DO LITTLE TO KEEP
TEMPERATURES FROM FALLING INTO THE 20S FOR MUCH OF THE AREA BY
MONDAY MORNING. WENT A LITTLE ABOVE GUIDANCE POPS IN THE SOUTH
TONIGHT BUT GUIDANCE TEMPERATURES WERE CLOSE THROUGH THE PERIOD AND
THE MAV WAS GENERALLY ACCEPTED. /22/
.LONG TERM...MONDAY THROUGH FRIDAY.
THE PRIMARY WEATHER CONCERN WILL BE TO ASSESS THE COLD AIR
ASSOCIATED WITH THE MID WEEK GULF SYSTEM. TO SEE HOW FAST OR SLOW
THE MODELS ARE GOING WITH THIS SYSTEM AND SEE IF WE CAN KEEP IT A
COLD RAIN AS WELL AS ALSO TO ASSESS TEMPS AND POPS FOR THE LONG TERM.
LOOKING AT THE GFS ENSEMBLES...CANADIAN...EUROPEAN...SREF AND UKMET.
ALL MODELS ARE IN GENERAL AGREEMENT ABOUT THE GENERAL UPPER PATTERN
WITH THE SHORT WAVE TROUGH COMING FROM THE PLAINS...WHICH WILL HELP
TO SET UP THE GULF SYSTEM FOR THE MIDDLE OF NEXT WEEK. AS WE GET INTO
THE MIDDLE OF THE WEEK THE MORE CONSISTENT EUROPEAN SLOWS THE SYSTEM
DOWN FOR TUESDAY THROUGH THURSDAY NIGHT...WHILE THE GFS AND CANADIAN WAS
FASTER WITH IT. SO HAVE ADJUSTED GRIDS FOR THE SLOWER EUROPEAN
SOLUTION. MOST OF THE ENSEMBLES ALONG WITH THE GFS AND EUROPEAN
AGREE ON THE PASSAGE OF A SHORT WAVE FOR FRIDAY. THE EUROPEAN MODEL
WAS A LITTLE SLOWER WITH MUCH MORE AMPLITUDE WITH THE UPPER TROUGH
ALONG WITH A 533 CLOSED LOW PUSHING INTO THE TENNESSEE VALLEY BY
EARLY SATURDAY. THE GFS HAD A 528 CLOSED LOW OVER THE GREAT LAKES AT
THIS TIME...WHILE MOST OF THE ENSEMBLES HAD A CLOSED LOW IN CANADA
WITH A FEW OVER THE GREAT LAKES. WITH THIS SYSTEM IT LOOKS TO BE
PRETTY DRY. EITHER WAY IT LOOKS TO BE A COOL PATTERN FOR THE LONG
TERM.
TAKING IT DAY BY DAY...
FOR MONDAY INTO TUESDAY...THE MODELS AND ENSEMBLES SHOWS A 1030-35 MB HIGH
PUSHING ACROSS THE SOUTHERN PLAINS. THE SURFACE HIGH WILL PUSH
NORTHEAST INTO THE NORTHERN MISSISSIPPI VALLEY ON TUESDAY. THE UPPER
RIDGING WILL BUILD ACROSS THE REGION EARLY IN THE WEEK. THERE WAS MORE
AMPLITUDE WITH THE EUROPEAN MODEL THEN WITH THE GFS AND ENSEMBLES
WITH THE APPROACH OF THE SHORT WAVE TROUGH.
FOR TUESDAY NIGHT INTO THURSDAY NIGHT...MODELS SHOWS THAT STRONG
ISENTROPIC UPGLIDE WILL DEVELOP ACROSS THE REGION AS SURFACE LOW
PRESSURE DEVELOPS IN THE NORTHWEST GULF. ALONG WITH THIS WE WILL GET
SOME STRONG ASCENT ALONG WITH STRONG Q DIVERGENCE. PRECIPITABLE WATER
WILL BE AROUND 1.2 INCHES. HPC SHOWS PRECIP OF ONE HALF TO AROUND
ONE INCH ACROSS MOST OF THE REGION. AS FAR AS INSTABILITY IS CONCERN
ELEVATED INSTABILITY WILL BE QUITE WEAK...SO WILL KEEP IT NONCONVECTIVE
RAIN. WE WILL HAVE A LAYER OF COLD AIR IN THE LOW LEVELS WITH THIS
SYSTEM. RIGHT NOW AS FAR AS PRECIPITATION IS CONCERN MODEL SOUNDINGS
SHOW THAT IT WILL BE A COLD RAIN WITH LOW LEVEL TEMPS AT 4-5C IN THE
CENTRAL AND SOUTH AND AROUND 3C IN THE NORTH. WET BUILD ZERO WILL BE
ABOVE 5KFT. FREEZING DEWPOINTS WILL STAY NORTH OF THE REGION DURING
THIS PERIOD...EXCEPT AT THE START OF THE PERIOD BEFORE THE RAIN
HITS. AS NOTED ABOVE HAVE FOLLOWED THE SLOWER ECMWF SOLUTION.
THIS SYSTEM WILL STILL BEAR WATCHING AS TO HOW COLD THE AIR WILL BE
ACROSS THE REGION WHEN THIS SYSTEM DEVELOPS. SO WITH THIS IN MIND
WILL KEEP IT ALL RAIN AT THIS TIME. THE RAINS ACCORDING TO THE ECMWF
WILL MOVE OUT OF THE REGION ON THURSDAY EVENING.
FOR FRIDAY...ON FRIDAY MORNING HIGH PRESSURE WILL MOVE INTO THE
REGION FROM THE WEST AS A SHORT WAVE PUSHES TOWARD THE REGION FROM
THE NORTHWEST. THIS SHORT WAVE WILL BRING SOME VERY LIGHT SPRINKLES
ACROSS THE REGION DURING FRIDAY AFTERNOON AND EVENING...WHICH MAY
BECOME A FEW FLURRIES EARLY SATURDAY. THINK THAT IT WILL BE TOO
LIGHT TO MENTION IN THE GRIDS. PRECIPITABLE WATER WILL BE AROUND ONE
HALF INCH.
AS FAR AS TEMPS ARE CONCERN...WE WILL GO THROUGH A COOL PERIOD WITH BELOW
NORMAL HIGHS AND AROUND NORMAL LOWS. FOR MONDAY HIGHS WILL BE MIDDLE
40S NORTH TO LOWER 50S SOUTH WENT CLOSE TO MAV GUIDANCE. FOR MONDAY
NIGHT LOWS WILL BE IN THE MID TO UPPER 20S...WENT CLOSE TO A BLEND OF
MOS GUIDANCE AND ENSEMBLE GUIDANCE. FOR THE RAINY PERIOD OF TUESDAY
THROUGH THURSDAY NIGHT KEPT NIGHTLY LOWS ABOVE FREEZING IN THE MIDDLE
30S...WHICH IS A LITTLE ABOVE MAV...ENSEMBLES AND MOS GUIDANCE.
HIGHS ON TUESDAY AND WEDNESDAY WILL BE IN THE 40S AND 50S. WENT
CLOSE TO A BLEND MOS GUIDANCE AND ENSEMBLE GUIDANCE. FOR FRIDAY
HIGHS ON FRIDAY WILL BE IN THE 40S...WENT CLOSE TO MAV GUIDANCE. FOR
FRIDAY NIGHT LOWS WILL BE IN THE MID TO UPPER 20S...WENT CLOSE TO
MOS GUIDANCE.
AS FAR AS POPS ARE CONCERN WENT CLOSE TO FOLLOWING THE EUROPEAN
MODEL WITH THE SLOWER SOLUTION OF THE MID WEEK SYSTEM. SO KEPT
HIGHER POPS FOR THE WEDNESDAY INTO THURSDAY. /17/
&&
.AVIATION...VFR CONDS WILL PREVAIL THIS PERIOD AS HIGH PRESSURE
DOMINATES THE REGION. OCCSNL GUSTY WINDS WILL CONTINUE AT GLH AND GWO
THIS MORNING INTO THE AFTERNOON AS THE PRES GRAD REMAINS TIGHT ACROSS
THIS AREA. LGT WINDS WILL DEVELOP LATE THIS AFTN/EARLY EVENING.
THERE IS A SLIGHT CHANCE OF LGT RAIN ACROSS SRN AREAS TOMORROW
MORNING AS A WEAK DISTURBANCE MOVES ACROSS THE NRN GULF. FOG/LOW
CIGS ARE NOT EXPECTED. /BK/
&&
.PRELIMINARY POINT TEMPS/POPS...
JACKSON 53 31 52 29 / 0 10 6 5
MERIDIAN 53 30 54 28 / 0 10 10 6
VICKSBURG 53 30 51 29 / 0 9 4 4
HATTIESBURG 55 34 57 29 / 0 17 15 5
NATCHEZ 53 32 54 28 / 0 16 8 3
GREENVILLE 51 29 47 27 / 0 8 4 5
GREENWOOD 52 28 48 26 / 0 9 4 5
&&
.JAN WATCHES/WARNINGS/ADVISORIES...
MS...NONE.
LA...NONE.
AR...NONE.
&&
$$
BK
