FXUS63 KSGF 212332
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
532 PM CST MON DEC 21 2009

...UPDATE TO AVIATION...

.DISCUSSION...

THE FORECAST CHALLENGES FOR THIS WEEK BEGIN TUESDAY AFTERNOON AS
INCREASING LOW LEVEL MOISTURE BRINGS THE CHANCE OF PRECIPITATION
INTO THE OZARKS. THIS MOISTURE WILL BEGIN TO STREAM NORTH FROM THE
WESTERN GULF AS A LOW LEVEL JET DEVELOPS WITH WINDS FORECAST TO
STRENGTHEN TO AROUND 40KTS BY LATE TUESDAY. THIS WILL INTERACT
WITH A WARM FRONT THAT WILL BE LIFTING NORTH ACROSS THE REGION
CAUSING PRECIPITATION TO FORM. THERE WILL ALSO BE SOME LIMITED
ELEVATED INSTABILITY ALONG AND SOUTH OF THE WARM FRONT THAT COULD
PRODUCE SOME ISOLATED THUNDERSTORMS.

THE CONCERN THEN SHIFTS TOWARD WEDNESDAY INTO THURSDAY AS THE
POSSIBILITY OF STRONG TO SEVERE THUNDERSTORMS AND FLASH FLOODING
WILL BE POSSIBLE. THE AFOREMENTIONED LOW LEVEL JET WILL CONTINUE
TO FEED MOISTURE INTO NORTHERN ARKANSAS AND SOUTHERN MISSOURI.
THIS ALONG WITH THE WAA AND A SURFACE LOW WHICH DEVELOPS AND
SWINGS ACROSS NORTHERN TEXAS AND OKLAHOMA...WILL PROVIDE THE NEEDED
INSTABILITY...LIFT...AND LOW LEVEL WIND SHEAR REQUIRED FOR STRONG TO
SEVERE THUNDERSTORM DEVELOPMENT. MODELS ARE INDICATING SURFACE
BASE CAPE AS MUCH AS 500JKG WEDNESDAY AFTERNOON FOR SOUTHEAST
KANSAS AND EXTREME SOUTHWEST MISSOURI AND NEAR 200JKG AGAIN
THURSDAY AFTERNOON FOR MUCH OF SOUTHERN MISSOURI. MODELS ARE IN
GOOD AGREEMENT IN DEVELOPING DEEP LAYER MOISTURE DURING THIS
PERIOD WITH THE POTENTIAL FOR HAIL...HIGH WINDS AND FLASH
FLOODING. WE ARE CURRENTLY THINKING THAT RAINFALL AMOUNTS WILL
RANGE FROM ONE TO THREE INCHES.

THIS IS THE PERIOD OF THE FORECAST HOWEVER THAT CONFIDENCE IN THE
MODELS BEGINS TO DROP. THE 12Z GFS AND THE 00Z ECMWF WERE VERY
SIMILAR WITH THE TRACK OF THE UPPER LEVEL AND SURFACE LOWS...THOUGH
THERE WAS SOME TIMING DIFFERENCES. THIS WOULD HAVE BROUGHT SOME
LIGHT SNOW OR FLURRIES TO THE OZARKS ON THE BACK SIDE OF THE
SYSTEM AS IT LIFTED NORTH AND BROUGHT SEVERE WEATHER TO THE AREA
AS PREVIOUSLY MENTIONED. THE LATEST...12Z RUN...ECMWF AS SHIFTED
THE SURFACE LOW FROM NEAR BARTLESVILLE TO FORT SMITH. THIS IS
NEARLY A 100 MILE SOUTHERLY SHIFT IN THE POSITION OF THE SURFACE
LOW THURSDAY MORNING. WHILE THIS IS THE FIRST INDICATION OF
THIS...AM NOT READY TO BITE ON IT YET...BUT A MORE SOUTHERLY TRACK
OF THE SURFACE LOW MAY CHANGE THE PRECIPITATION TYPE FOR LATER IN
THE DAY ON THURSDAY AND INTO CHRISTMAS MORNING. THIS COULD DEVELOP
SOME HEAVIER SNOW ACROSS MUCH OF EASTERN KANSAS...AS FAR EAST AS THE
HIGHWAY 71 CORRIDOR IN MISSOURI. WOULD LIKE TO SEE FUTURE RUNS
SHOW THIS MORE CONSISTENTLY BEFORE WE DECIDE TO FORECAST
ACCUMULATIONS FOR THE OSAGE PLAINS. EITHER WAY...AS THE LOW LIFTS
NORTH OF THE REGION...MOISTURE ON THE BACK SIDE OF THE LOW COULD
CREATE SOME LIGHT SNOW OF FLURRIES THURSDAY NIGHT AND INTO
CHRISTMAS DAY.

COLD TEMPERATURES ARE THEN EXPECTED TO REMAIN ACROSS THE REGION
THROUGH THE WEEKEND AND INTO NEXT WEEK. 925 TEMPERATURES BEHIND
THE SYSTEM WILL FALL INTO THE -10 TO -12 DEGREE C RANGE FOR THE
WEEKEND. THESE TEMPERATURES ARE CORRELATED WITH HIGHS IN THE
UPPER 20S TO LOW 30S...AND LOWS IN THE TEENS INTO THE BEGINNING OF
NEXT WEEK.

FOR THOSE TRAVELING ACROSS THE CENTRAL STATES THIS FOR THE
HOLIDAYS...STAY TUNED TO THE LATEST INFORMATION WITH THE POTENTIAL OF SEVERE
WEATHER AND A SIGNIFICANT WINTER STORM IN THE FORECAST.

HATCH

&&

.AVIATION...

FOR THE 00Z KSGF...KJLN AND KBBG TAFS...SOUTHEAST WINDS AND HIGH
CLOUDS WILL BE IN PLACE ACROSS THE TAF SITES OVERNIGHT. A STRONG
LOW LEVEL JET WILL SET UP OVER THE REGION TONIGHT WHICH MAY CREATE
LOW LEVEL WIND SHEAR CONCERNS AT THE TAF SITES. THE LOW LEVEL JET
WILL ALSO BRING AN INCREASE IN LOW LEVEL MOISTURE FROM THE 
SOUTH...WHICH MAY LEAD OF MVFR CEILINGS SPREADING ACROSS THE TAF
SITES TOMORROW.

&&

.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

$$