Severe Thunderstorm Warning 207, NWS Kansas City, MO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO
430 PM CDT MON AUG 19 2002

430 PM...
MAIN FORECAST CONCERN IN THE SHORT TERM IS WITH THREAT OF STORMS
TONIGHT AND TUESDAY. CURRENTLY WATCHING ISOLATED STORMS GOING IN
AREA OF STEEP LAPSE RATES AT THE 700 TO 500 MB LEVEL ACROSS
SOUTHEAST NEBRASKA AND SOUTHWEST IOWA. WILL NOT PUT POPS IN FORECAST
FOR THESE STORMS AS THEY SHOULD STAY NORTH OF BORDER...WITH PERHAPS
ONLY ONE OR TWO CELLS CLIPPING THE AREA. THESE STORMS SHOULD DIE OUT
AFTER SUNSET AS ONLY HAVE WEAK UPPER WAVE TO SUPPORT THEM AND LOSS
OF DAYTIME HEATING WILL DECREASE LAPSE RATES.

FOR THE SOUTHERN PART OF FORECAST AREA...FRONT IS VERY CLOSE SO WILL
KEEP LOW POPS IN THAT AREA EARLY THIS EVENING. THEN LOOKING FOR WARM
AIR ADVECTION TO START DEVELOPING STORMS IN EASTERN KANSAS
OVERNIGHT. WILL LEAVE MENTION IN WESTERN PART OF FORECAST AREA THAT
WE HAD GOING AS CAN NOT RULE OUT STORMS DEVELOPING THAT FAR EAST AND
CONTINUING INTO TUESDAY MORNING.

HAVING DOUBTS WE WILL SEE MUCH DEVELOPMENT ON TUESDAY
AFTERNOON...BUT MODELS CONTINUE TO PRODUCE QPF FIELDS ACROSS REGION
WITH SOME INSTABILITY AND CAP WEAKENING SO WILL KEEP LOW POPS GOING.

IN THE LONGER RANGE...THE UNSEASONABLY ENERGETIC WEATHER PATTERN IS
FORECAST TO CONTINUE THROUGH THE END OF THE WEEK OVER THE US.  THE
STRONG BELT OF WESTERLIES IS FORECAST TO MIGRATE NORTH FOR THE
MIDDLE PART OF THE WEEK ONLY TO RETURN FORCEFULLY INTO THE GREAT
LAKES BY SATURDAY MORNING.  THERE ARE SOME DISCREPANCIES BETWEEN
MEDIUM RANGE SOLUTIONS.  THE AVN HAS BEEN THE MOST CONSISTENT, AND
IS ALSO THE MOST AMPLIFIED BY THE END OF THE WEEK.  THE ECMWF IS
WEAKER AND MORE ZONAL WITH ITS SOLUTION.  THE NOGAPS AND CANADIAN
MODELS LEND CREDENCE TO THE AVN SOLUTION, SO THE AVN WAS USED FOR
THIS PACKAGE.

ACCORDING TO THE AVN, TWO COLD FRONTS WILL AFFECT THE CENTRAL UNITED
STATES FOR THE END OF THE WEEK.  THE FIRST IS A WEAK COOL FRONT
PROGGED TO STALL IN CENTRAL IOWA ON THURSDAY.  IT IS DOUBTFUL THAT
ANY PRECIPITATION GENERATED BY THIS FRONT WILL DROP SOUTH OF THE
MISSOURI IOWA BORDER, WITH THE SURFACE FRONT DRAPED FROM OMAHA TO
DES MOINES.  A MUCH STRONGER FRONT IS PROGGED FOR LATE IN THE DAY ON
FRIDAY.  THE AVN SUGGESTS THAT THIS FRONT WILL PUSH THROUGH KANSAS
AND NORTHERN MISSOURI ON FRIDAY NIGHT. TIMING IS POOR FOR DIURNAL
STORMS, BUT THE FRONT MAY BE STRONG ENOUGH TO GENERATE SOME POST
FRONTAL PRECIPITATION, EVEN INTO SATURDAY MORNING SOUTH OF THE
MISSOURI RIVER.
KOCH

1130 AM...
DID AN AFTERNOON REVISION TO THE FORECASTS TO COOL TEMPERATURES A
BIT. DECENT COLD AIR ADVECTION GOING ON WITH READINGS STILL IN THE
LOWER 70S WHERE SUNNY SKIES HAVE BEEN ALONG THE IOWA BORDER. CLOUD
COVER ACROSS NORTHEAST KANSAS AND INTO CENTRAL MISSOURI WILL
CONTINUE TO ERODE...BUT WILL ALSO HELP TO INHIBIT TEMPERATURES A BIT
TODAY. FRONT CONTINUES TO MAKE PROGRESS SOUTHWARD...SO EXPECT
SOUTHERN PART OF FORECAST AREA WILL ONLY CLIMB A FEW MORE DEGREES AS
WELL. WILL LEAVE MENTION OF PRECIPITATION FOR LATE TODAY IN THE
SOUTHERN HALF OF FORECAST AREA WITH PROFILERS STILL SHOWING 850
BOUNDARY IN THE AREA AND SOME DIFFERENTIAL HEATING POSSIBLE ALONG
THE CLOUD BOUNDARIES...BUT WILL KEEP POPS LOW AS MODELS SHOWING
INSTABILITY IS SUPPRESSED PRETTY MUCH SOUTH OF FORECAST AREA THIS
AFTERNOON.

PC

740 AM...
WITH THE THREAT OF HEAVY RAIN OVER FOR NORTH CENTRAL MISSOURI...WILL
BE REVISING THE FORECAST TO REMOVE MENTION OF A FLOOD WATCH.

PC

625 AM...
THE 850 MB FRONT SHOT NORTH YESTERDAY ALLOWING A STRONG CAP TO
FORM OVER EASTERN KANSAS AND NORTH MISSOURI.  OVERNIGHT
CONVECTION STARTED TO GET GOING ON THE NORTHERN EDGE OF THE 12C 700
MB ISOTHERM JUST NORTH OF THE MISSOURI/IOWA BORDER.  CONVECTION
THAT HAD BEGUN IN WESTERN KANSAS OVERNIGHT MOVED DUE EAST AND WAS
FORMING AN ORGANIZED LINE AS IT MOVED THROUGH TOPEKAS AREA INTO
EASTERN KANSAS AND WESTERN MISSOURI.

MODELS ARE PROGGING THE SURFACE BOUNDARY TO DROP BACK SOUTH AS A
SHORT WAVE SWINGS THROUGH THE UPPER MIDWEST INTO THE GREAT LAKES.
BOTH THE AVN AND ETA MODELS ARE AGREEING ON ONLY PUSHING THE SURFACE
FRONT AS FAR SOUTH AS CENTRAL MISSOURI BEFORE WASHING OUT.  THIS
WOULD CONTINUE TO INDICATE THAT ANY CONVECTION FOR THIS AFTERNOON
AND THIS EVENING WILL BE FOCUSED IN THE SOUTHERN SECTIONS OF OUR
WARNING AREA TODAY.  DESPITE THE SAGGING SURFACE BOUNDARY I HAVE
GONE AHEAD AND BUMPED TEMPERATURES ON THE WESTERN EDGE OF MISSOURI
AS THERE APPEARS TO BE A LACK OF COOL WEATHER BEHIND THE
FRONT...AND 850 MB TEMPERATURES REMAIN RELATIVELY WARM.  FOR THE
OVERNIGHT HOURS I HAVE PUSHED THE CHANCES OF THUNDER INTO THE NORTH
HALF OF THE CWA.  THE LOW LEVEL JET SHOULD FIRE CONVECTION OFF ALONG
THE KANSAS/NEBRASKA BORDER AS THETA-E ADVECTION PUSHES THE GRADIENT
NORTHEAST.  FEW OTHER CHANGES MADE BEYOND A FEW TWEAKS TO
TEMPERATURES.

CUTTER

.EAX...
KS...NONE.
MO...NONE.