Area Forecast Discussion

000

FXUS64 KJAN 132159

AFDJAN

AREA FORECAST DISCUSSION

NATIONAL WEATHER SERVICE JACKSON MS

359 PM CST MON NOV 13 2006

.DISCUSSION...

SHORT TERM(TONIGHT THROUGH WEDNESDAY)...WEAK UPPER TROUGH AXIS HAS

JUST ABOUT CLEARED THE REGION WITH THINNING CIRRUS ALLOWING PLENTY OF

SUNSHINE LATE THIS AFTERNOON. SURFACE RIDGE(1019MB) AXIS REMAINS IN

TACT ALONG THE MS RIVER SO MORE GOOD RADIATIONAL COOLING FOR TONIGHT

THAT SHOULD RESULT IN READINGS FROM U30S EAST TO LOWER 40S WEST. LOOK

FOR INCREASING HIGH LEVEL CLOUDS TOWARD MORNING AS A POWERFUL UPPER

JET CORE BLASTS INTO THE CENTRAL ROCKIES AND BEGINS TO CARVE OUT A

MAJOR STORM SYSTEM FOR THE MS VALLEY AND POINTS EAST FOR THE NEXT

COUPLE OF DAYS.

MODELS TAKING THE CURRENT 180KT 200MB JET IN OREGON THE CENTRAL CONUS AS 140KT CORE DIVING TOWARD THE ARKLATEX TUESDAY NIGHT. THIS JET WILL DIG OUT A VERY DEEP MID LEVEL TROUGH THAT APPEARS MORE LIKELY NOW TO BRING SEVERE WEATHER TO THE ARKLAMISS LATE TUESDAY NIGHT THROUGH WEDNESDAY MORNING. A DEEPENING 500MB AND SURFACE LOW WILL MOVE FROM SRN OK TOWARD TN FROM TUESDAY NIGHT INTO WEDNESDAY. BOTH 12Z NAM12 AND GFS TRACK THE SURFACE LOW FROM SERN OK(991MB) TUESDAY NIGHT AT MIDNIGHT TO NEAR MEMPHIS(989MB) WEDNESDAY MORNING 6AM. MODELS MUCH MORE CONSISTENT AND NOW IN LINE WITH THE TIMING OF THIS SYSTEM AS IT MOVES ACROSS THE

ARKLAMISS.

EXPECT SCATTERED TSRA TO BREAK OUT IN STRONG WARM ADVECTION TUESDAY

NIGHT AS BOTH LATEST GFS AND NAM12 ARE BRINGING UP MIDDLE 60S SURFACE

DEWPOINTS ACROSS THE AREA EARLY WEDNESDAY AHEAD OF THE SYSTEM. THE

MLCAPES HAVE JUMPED TO THE 800-1400J/KG RANGE(GFS ACTUALLY MORE

UNSTABLE THIS TIME). DEEP LAYER SHEAR WITH THIS EVENT BECOMES

ADEQUATE DURING TUESDAY EVENING WHEN THE MAIN SEVERE RISK WILL BE

WINDS AND HAIL...BUT LOWER LEVEL SHEAR RAPIDLY BECOMES IMPRESSIVE

WEDNESDAY MORNING WITH 0-1KM HELICITIES OF NEAR 500 M^2/S^2 AND 0-3KM

VALUES 600-800 M^2/S^2 BETWEEN 09-18Z. THE GREATEST RISK FOR

TORNADOES CURRENTLY APPEARS TO DEVELOP SOUTH OF THE I-20 CORRIDOR

BEFORE SUNRISE WHERE THE HIGHEST DEWPOINT RECOVERY WILL BE WITH

DEWPOINTS NEAR 67F.

ALL MODES OF SEVERE WILL BE IN PLAY WEDNESDAY MORNING AS THE MID

LEVEL(700MB) SPEED MAX OF NEAR 70KTS+ MOVES E BETWEEN I-20/HWY 82

DURING THE MORNING WHILE ONGOING SUPERCELL STORMS CONGEAL INTO A

SQUALL LINE. LAST TWO MODEL RUNS ALSO CONSISTENT IN ERUPTING A LINEAR

MCS ALONG A KMEI-KMCB LINE AS THE LINE MATURES AND ENHANCES DAMAGING

WINDS FOR SERN MS DURING THE MIDDAY HOURS. THE ENTIRE LINE EXITS ERN

MS BY MID AFTERNOON WITH GUSTY W WINDS OF 20-30 MPH...A FEW GUSTS IN

THE COLD AIR COULD REACH 40 MPH. WILL PROBABLY NEED A WIND ADVISORY

OF SOME SORT FOR WEDNESDAY AFTERNOON AND EVENING./40/

LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY. THE FORECAST BEYOND

WEDNESDAY WAS FAIRLY QUIET...SO DID NOT MAKE ANY MAJOR CHANGES TO

THE FORECAST. NOT REAL CONFIDENT IN THE GFS POPS FOR WEDNESDAY NIGHT

THURSDAY...BUT STILL WENT WITH GUIDANCE. LOOKS LIKE THE BOUNDARY

WILL BE OUT OF THE AREA BY WEDNESDAY...BUT MOISTURE SHOULD WRAP

AROUND THE LOW. THE UPPER TROUGH AXIS WILL SWING THROUGH THE AREA

WEDNESDAY NIGHT...SO LOOKING FOR LIGHT RAIN AND DRIZZLE THROUGH

EARLY THURSDAY. MAINTAINED SLIGHT CHANCE POPS THROUGH 18Z...BUT

SUSPECT THE PRECIP WILL HAVE ENDED BY THEN. LOOKS LIKE A FEW WEAK

UPPER LEVEL DISTURBANCES WILL MOVE THROUGH THE CWA FROM THURSDAY TO

MONDAY WITH LITTLE IMPACT. THE AREA MAY SEE SOME CLOUDS FRIDAY AND

AGAIN SUNDAY. AT THIS TIME NOT LOOKING FOR RAIN...BUT LIGHT RAIN AND

DRIZZLE CAN NOT BE RULED OUT. LOOKS LIKE MOSTLY PACIFIC AIR WILL BE

FLOWING INTO THE REGION...SO NOT EXPECTING ANY REAL COLD

TEMPERATURES. CLEAR SKIES AND RADIATIONAL COOLING MAY LEAD TO SOME

FREEZING TEMPS IN THE EAST A FEW NIGHTS...THURSDAY NIGHT AND MAYBE

AGAIN SUNDAY NIGHT. OTHERWISE NEAR NORMAL FALL CONDITIONS CAN BE

EXPECTED FROM THURSDAY TO MONDAY./07/

&&

.AVIATION...VFR CLEAR EXPECTED THROUGH THE EVENING WITH MORE HIGH

LEVEL CIRRUS ARRIVING AFTER 04Z FROM WEST TO EAST. SOME SHALLOW MVFR

FOG DEVELOPS 09-14Z TUESDAY MAINLY FOR EASTERN LOCATIONS WHERE BRIEF

IFR VISIBILITIES WILL BE POSSIBLE. MULI-LAYER CLOUDS BEGIN ARRIVING

AFTER 16Z OR SO WITH SOME BROKEN CEILINGS ABOVE 10K FEET./40/

&&

.PRELIMINARY POINT TEMPS/POPS...

JACKSON       43  68  58  67 /   5  18  94  78

MERIDIAN      36  68  55  70 /   4  12  82  82

VICKSBURG     47  66  57  65 /   5  24 100  69

HATTIESBURG   41  70  61  75 /   5  20  78  79

NATCHEZ       48  70  59  67 /   4  30 100  63

GREENVILLE    46  65  55  62 /   5  13 100  79

GREENWOOD     42  63  57  66 /   5  10  96  80

&&

.JAN WATCHES/WARNINGS/ADVISORIES...

MS...NONE.

LA...NONE.

AR...NONE.

&&

$$