Friday, July 30, 2010

Area Forecast Discussion - South Central/Southwest Missouri

FXUS63 KSGF 302359
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
659 PM CDT FRI JUL 30 2010

..UPDATE TO AVIATION...

..MESOSCALE CONVECTIVE DISCUSSION...

UPDATE...
/ISSUED 658 PM CDT FRI JUL 30 2010/

A LINE OF STORMS IS PUSHING ACROSS CENTRAL MISSOURI INTO EASTERN
MISSOURI EARLY THIS EVENING. THE STRONGEST STORMS REMAIN OF NORTH
EAST OF THE AREA...WHERE BETTER WIND SHEAR AND SHEAR COLD POOL
BALANCE ARE OCCURRING. THE SHEAR COLD POOL BALANCE ACROSS THE
NORTHEAST CWA IS MORE FAVORABLE TOWARDS THE COLD POOL...AND THIS IS
WHAT WE ARE SEEING AS THE OUTFLOW BOUNDARY IS OUTRUNNING THE
CONVECTION. THEREFORE THE SEVERE POTENTIAL IS LIKELY DECREASING
AS THE STORMS ARE BEHIND THE OUTFLOW BOUNDARY WHERE INSTABILITY IS
WEAKER. THERE COULD STILL BE HEAVY RAINFALL AND SOME GUSTY WINDS
TO 30 MPH OR SO...BUT THE SEVERE RISK IS DECREASING SO WE WILL
LIKELY LET THE SEVERE THUNDERSTORM WATCH GO EARLY.

THUNDERSTORMS WILL STILL BE POSSIBLE ACROSS THE EASTERN CWA
THOUGH MID EVENING AS THIS ACTIVITY PUSHES SOUTH. LOCALLY HEAVY
RAINFALL WILL BE THE MAIN RISK WITH THIS ACTIVITY. ADDITIONAL
THUNDERSTORMS HAVE DEVELOPED ACROSS PORTIONS OF NORTHEASTERN
KANSAS INTO NORTHWESTERN MISSOURI EARLY THIS EVENING. THIS
ACTIVITY WILL SLOWLY PUSH SOUTH. HOWEVER...THINK IT WILL DISSIPATE
AS IT APPROACHES THE CWA OVERNIGHT AS INSTABILITY WEAKENS DUE TO
THE LOSS OF DAY TIME HEATING AND A STRONG CAP THAT REMAINS IN
PLACE ACROSS THE AREA. A FEW LIGHT SHOWERS WILL LIKELY BE ALL THAT
REMAINS OF THOSE STORMS AS THEY PUSH INTO THE AREA. HAVE UPDATED
POPS THIS EVENING BASED ON CURRENT RADAR TRENDS.

TEMPERATURES AND HEAT INDEX VALUES ARE ALSO STARTING TO DECREASE
THIS EVENING AND WILL LIKELY LET THE HEAT ADVISORY GO EARLY TOO.

WISE

&&

DISCUSSION...
/ISSUED 300 PM CDT FRI JUL 30 2010/

THUNDERSTORM DEVELOPMENT HAD BEEN CONFINED TO CENTRAL AND SOUTH
CENTRAL MISSOURI THIS AFTERNOON IN CLOSE PROXIMITY TO A WEAK STALLED
FRONT WITHIN AN AXIS OF MODEST 850 MB CONVERGENCE. MORE SUBSTANTIAL
CONVECTION WAS FIRING ACROSS NORTHERN MISSOURI AS A MINOR MID LEVEL
SHORTWAVE DROPPED SOUTHEAST INTO NORTHERN MISSOURI.

SHORT TERM (TONIGHT THROUGH SUNDAY)...

ISOLATED TO SCATTERED CONVECTION WILL BE FOCUSED FROM CENTRAL
INTO SOUTH CENTRAL MISSOURI THE REMAINDER OF THE AFTERNOON WITHIN
AXIS OF BEST INSTABILITY AND LOW LEVEL CONVERGENCE. WILL BE
MONITORING THE DEVELOPING LINEAR CONVECTIVE COMPLEX ACROSS
NORTHERN MISSOURI AS IT COULD IMPACT CENTRAL MISSOURI INTO THE
EASTERN OZARKS. CONVECTION HAS BEEN CONFINED MAINLY IN THE
PERIPHERY OF THE 700 MB THERMAL RIDGE. THEREFORE SOME QUESTION TO
HOW FAR SOUTH INTO THE OZARKS THIS ACTIVITY WILL MAKE IT. HEAVY
RAINFALL RESULTING IN LOCALIZED FLOODING...AND THE POTENTIAL OF
DAMAGING DOWN BURST WINDS CANNOT BE RULED OUT PRIMARILY ACROSS
CENTRAL AND SOUTH CENTRAL MISSOURI INTO EARLY THIS EVENING.

THE SHORTWAVE WILL SLIDE SOUTHEAST ACROSS THE REGION TONIGHT. THE
LOW LEVEL JET WILL STRENGTHEN IN RESPONSE WITH THE BEST CONVERGENCE
ACROSS CENTRAL AND EASTERN MISSOURI, THEREFORE THE BEST CHANCE FOR
THUNDERSTORM DEVELOPMENT TONIGHT WILL CONTINUE TO BE FROM THE LAKE
OF THE OZARKS REGION INTO THE EASTERN OZARKS.

A WEAK FRONT WILL DROP SOUTH THROUGH THE AREA SATURDAY MORNING AS
THE SHORTWAVE EXITS THE AREA. CONVECTIVE DEVELOPMENT WILL BE
POSSIBLE ALONG THIS BOUNDARY SATURDAY AND FOCUSED ALONG AND SOUTH
OF HIGHWAY 60. SURFACE DEW POINTS MAY ACTUALLY RISE SATURDAY WITH
MOISTURE POOLING ALONG THE FRONT BUT HIGH TEMPERATURES ARE
SOMEWHAT IN QUESTION WITH MORE CLOUD COVER EXPECTED.

LITTLE IN THE WAY OF CONVECTION IS EXPECTED SUNDAY AS 500 MB
HEIGHTS BUILD OVER THE REGION AND A NORTHEASTERLY FLOW IS
MAINTAINED AROUND SURFACE HIGH PRESSURE CENTERED OVER THE GREAT
LAKES. HIGH TEMPERATURES WILL RISE INTO THE LOWER AND MIDDLE 90S
BUT MODELS SUGGEST THAT SURFACE DEW POINTS WILL BE A BIT LOWER DUE
TO THE MORE EASTERLY FLOW.

WITH THE UNCERTAINTY OF TEMPERATURES AND DEW POINTS BECAUSE OF THE
PROXIMITY OF THE FRONT AND THE SHIFT IN THE LOW LEVEL FLOW...ADDITIONAL
HEAT ADVISORIES WILL NOT BE ISSUED AT THIS TIME.

FOSTER

LONG TERM (MONDAY THROUGH FRIDAY)...

EXTENT OF HEAT REMAINS THE FOCUS THROUGH AT LEAST MIDWEEK. LONG
RANGE MODELS HAVE DIFFERENCES IN HOW FAR NORTH H5 HEIGHTS TO
BUILD...THOUGH BELIEVE FORECAST TO HINGE ON THE PROXIMITY OF THE
ACTIVE JET MEANDERING ACROSS THE NORTHERN TIER OF THE NATION AND THE
TIMING ON WHEN A SURFACE FRONT REACHES THE OZARKS.

GFS/ECM BOTH BUILD 594+ DM HEIGHTS NORTHWARD INTO AT LEAST NRN MO
THROUGH THE EARLY PART OF NEXT WEEK. THIS IS OCCURRING AS A
SHORTWAVE TRAVERSES SOUTHERN CANADA AND INTO THE GREAT LAKES BY
TUESDAY. MODELS DIFFER ON HOW FAR SOUTH AN ASSOCIATED COLD FRONT
WILL DESCEND INTO THE HEAT RIDGE IMPACTING CONFIDENCE ON HOW LONG TO
THE MAINTAIN THE SEASONABLY HOT WEATHER.

WHILE WEDNESDAY MAY SEE SOME RELIEF AS MOISTURE CONVERGES LEADING TO
AT LEAST ENHANCED CUMULUS IF NOT SCT TSRA...ANTICIPATE WEAKENING
FRONT TO DESCEND THROUGH FORECAST AREA ON THURSDAY DROPPING
HEAT INDICES FINALLY OUT OF THE 100S.

IT SHOULD BE NOTED THAT THE INCREASE IN MOISTURE CONVERGENCE WILL
LIKELY DRIVE DEW POINTS UPWARD AS THE FRONT APPROACHES. AS THIS
WILL FOLLOW FOUR IF NOT FIVE DAYS OF HEAT INDICES OF AT LEAST 100
AND POSSIBLY OF OVER 105 DEGREES...THIS MOISTURE INCREASE ON TOP OF
THE CUMULATIVE PERIOD OF SUSTAINED HEAT MAY MAKE FOR A DANGEROUS
HEALTH RISK ON WEDNESDAY ESPECIALLY IF PRECIPITATION DOESNT
FORM.

RUNNELS

&&

AVIATION...

FOR THE 00Z KSGF...KJLN AND KBBG TAFS...VFR CONDITIONS ARE
EXPECTED OVER THE NEXT 24 HOURS. A WEAK COLD FRONT WILL SLIDE
SOUTH THROUGH THE TAF SITES EARLY SATURDAY MORNING...WITH THE
WINDS SHIFTING TO THE NORTHWEST BEHIND THE FRONT. A FEW ISOLATED TO
SCATTERED SHOWERS AND THUNDERSTORMS MAY DEVELOP ALONG THE FRONT
ACROSS SOUTHERN MISSOURI SATURDAY MORNING. HOWEVER...THINK THE BETTER
CHANCES FOR THIS DEVELOPMENT WILL BE SOUTH OF THE TAF SITES
SATURDAY AFTERNOON WHEN THE INSTABILITY INCREASES WITH THE HEATING
OF THE DAY. SO HAVE LEFT SHOWERS AND THUNDERSTORMS OUT OF THE TAFS AT
THIS TIME BUT SOMETHING TO WATCH.

WISE

&&

SGF WATCHES/WARNINGS/ADVISORIES...
MO...HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR MOZ066-077-088-093-
101.

KS...HEAT ADVISORY UNTIL 9 PM CDT THIS EVENING FOR KSZ073-097-101.

&&

$$


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