FXUS63 KSGF 080539
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
1139 PM CST MON DEC 7 2009

...UPDATE TO AVIATION...

...MESOSCALE DISCUSSION...

.UPDATE...

ISENTROPIC UPGLIDE GETTING INTO GEAR ACROSS THE SOUTH AS A LOW
LEVEL JET GETS BETTER ORGANIZED. SCT SHRA DEVELOPING ACROSS ARK
GENERATING MINIMAL SFC REPORTS ACCORDING TO AREA OBS AT THIS
TIME. THIS ACTIVITY IS ENCOUNTERING A DECENT DRY LAYER AS SEEN
BEST ON THE 00Z LZK RAOB. PERSISTENT ISENTROPIC LIFT WILL
CONTINUE AND LEAD TO MOISTENING AS THE NIGHT PROGRESSES. LOOKING
AT THE VARIOUS WRF MODELS...A BAND OF SCT SHRA WILL CUT ACROSS
SOUTH CENTRAL MO TONIGHT. TEMPS WILL FLIRT OH SO CLOSELY WITH THE
FREEZING MARK...BUT EXPECTATIONS ARE THAT MOST OF THIS ACTIVITY
WILL BE LIGHT AND IN THE LIQUID FORM. AN ELEVATED LIGHT GLAZE IS
POSSIBLE A FEW HOURS AROUND SUNRISE IN VALLEYS...BUT WAA REGIME
PROGRESSIVELY GETS IN GEAR AS THE MORNING PROGRESSES. IN
ADDITION...PRECIP WILL MIX DOWN SLIGHTLY WARMER AIR AS WELL. COULD
SEE A BIT OF SLEET MIX IN ACROSS SOUTH CENTRAL MO...BUT AGAIN WITH
TEMPS AT OR JUST ABOVE FREEZING CONCERNS FOR ACCUM ARE MINIMAL AND
CONFINED TO A VERY BRIEF WINDOW OF OPPORTUNITY. COULD SEE POCKETS
OF VERY LIGHT DZ/FZDZ ACROSS THE REST OF THE AREA...BUT AGAIN
ACCUMULATIONS WILL BE TOUGH TO COME BY WITH TEMPS RIGHT AROUND THE
FREEZING MARK.

HAVE UPDATED TEMPS AND POPS OVERNIGHT TO ACCOUNT FOR LATEST
TRENDS.

GAGAN

&&

.DISCUSSION...

FORECAST CHALLENGES DEAL WITH PRECIP TYPE AND TIMING WITH OUR NEXT
STORM SYSTEM...FOLLOWED BY TEMPERATURES BEHIND THE STORM SYSTEM
ONCE IT MOVES OUT.

CURRENTLY...AREA UNDER INFLUENCE OF HIGH PRESSURE CENTERED OVER
THE NORTHERN PLAINS WITH WIDESPREAD STRATUS. TEMPERATURES ACROSS
THE AREA REMAIN IN THE MID 30S EARLY THIS AFTERNOON. FURTHER
WEST...OUR STORM SYSTEM THAT WILL IMPACT THE AREA TUESDAY INTO
WEDNESDAY HAS JUST ABOUT ROUNDED THE BASE OF THE LONG WAVE TROUGH
OVER CENTRAL CALIFORNIA AND IS SHOWING SOME EASTWARD MOVEMENT OVER
THE PAST FEW IMAGES.

FOR TONIGHT...SOUTHEAST WINDS PICK UP AS SURFACE LOW OVER THE
TEXAS/OKLAHOMA PANHANDLE BEGINS TO DEEPEN. WARM AIR ADVECTION TO
COMMENCE ACROSS THE AREA BY THIS EVENING AS 850MB TEMPERATURES
INCREASE FROM -1C THIS MORNING...UP TO AROUND +4C TOMORROW
MORNING. WILL PROBABLY SEE OUR LOW TEMPERATURES EARLY THIS EVENING
WITH A SLOW RISE THROUGH THE OVERNIGHT HOURS. WARM FRONT LIFTS
NORTH INTO NORTHERN MISSOURI BY MORNING AND ASSOCIATED BROAD SCALE
ISENTROPIC LIFT IN THE WARM SECTOR TO BEGIN TO KICK OFF SOME RAIN
TUESDAY MORNING. COULD BE SOME POCKETS OF SUB-FREEZING
TEMPERATURES THAT COULD LEAD TO SOME FREEZING RAIN IN
LOCATIONS...BUT FOR THE MOST PART...DO NOT BELIEVE FREEZING RAIN
TO BE WIDESPREAD AS TEMPERATURES TUESDAY MORNING SHOULD BE AT OR
SLIGHTLY ABOVE FREEZING.

SURFACE LOW ENTERS THE CWA NEAR JOPLIN BY TUESDAY AFTERNOON WITH
THE ENTIRE CWA IN THE WARM SECTOR...SO ALL PRECIP SHOULD BE IN THE
FORM OF RAIN TUESDAY AFTERNOON. LOOKS LIKE THE SGF CWA WILL
PROBABLY GET DRY SLOTTED FOR THE MOST PART AS CONVECTION TO THE
SOUTH LOOKS TO CUT OFF MOST GULF MOISTURE RETURN AND DEFORMATION
ZONE ASSOCIATED WITH THE LOW STAYS NORTH OF THE CWA. BY TUESDAY
EVENING...SURFACE LOW TRACKS TO NEAR SAINT LOUIS AFTER MIDNIGHT.
SIGNIFICANT COLD AIR ADVECTION BEHIND THE FRONT MOVES INTO THE
AREA WEDNESDAY MORNING AS 850MB TEMPERATURES PLUMMET TO -14C
WEDNESDAY MORNING. HIGHS ON WEDNESDAY WILL PROBABLY BE AROUND
MIDNIGHT WITH FALLING TEMPERATURES THROUGHOUT THE DAY. HIGHS
WEDNESDAY AFTERNOON WILL STRUGGLE TO GET OUT OF THE MID 20S.

ONE OTHER HAZARD FOR TUESDAY EVENING INTO WEDNESDAY IS THE STRONG
PRESSURE GRADIENT WE WILL SEE WITH THE SURFACE LOW. WIND SPEEDS IN
EXCESS OF 25 MPH WITH HIGHER GUSTS SHOULD PERSIST THROUGH THE DAY
WITH THESE FALLING TEMPERATURES. WIND CHILLS WILL APPROACH ZERO
DEGREES WEDNESDAY AFTERNOON...BEFORE WIND SPEEDS BEGIN TO DIE OFF
WEDNESDAY EVENING. BY THURSDAY MORNING...FORECAST MODELS SHOWING
SURFACE HIGH ACROSS SOUTHWEST MISSOURI WITH WINDS WEAKENING.
MORNING LOWS THURSDAY COULD FALL INTO THE SINGLE DIGITS.

NEXT CHANCE FOR WINTRY PRECIP LOOKS TO BE FRIDAY AS GULF MOISTURE
BEGINS TO RETURN AHEAD OF A SURFACE LOW IN NORTHERN TEXAS.

CLAYCOMB

&&

.AVIATION...

FOR THE 06Z TAF PACKAGE...LONG DURATION CIG/VIS RESTRICTIONS
EXPECTED FOR JLN/SGF/BBG. A STRONG STORM SYSTEM WILL MOVE INTO THE
REGION DURING THIS TAF CYCLE. MVFR CIGS WILL GRADUALLY LOWER TO
IFR BY DAYBREAK. SCT SHRA DEVELOPING OVER ARK AT THIS HOUR WILL
FLIRT WITH BBG...WITH A BETTER SHOT AT -DZ DEVELOPING WITH VIS
LOWERING INTO MVFR. BRIEF PERIOD OF -SHRA EXPECTED DURING THE
DAYLIGHT HOURS OF THE MORNING WILL SWITCH BACK TO -DZ AS THE
BETTER LIFT SPLITS TO THE NORTH AND SOUTH OF THE AERODROMES. IFR
WILL CONTINUE THROUGH MUCH OF THE DAY WITH INCREASING WINDS AT THE
END OF THE TAF CYCLE AS STRONG LOW PRESSURE MOVES OVER THE AREA.

GAGAN

&&

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

$$