[LeArc] Forecast Discussion : MLI@ 9/13/02 2:06:13 PM

[learc@mailman.qth.net]

The following weather message is provided by McDonough County E.S.D.A.


FXUS63 KDVN 131911
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
210 PM CDT FRI SEP 13 2002

.OVERVIEW...BROAD...FAIRLY WEAK UPPER LEVEL SYSTEM NOW IN CENTRAL AND
SOUTHERN PLAINS CONTINUES TO SPIN SLOWLY EAST NORTHEAST WITH LEADING
EDGE OF MID DECK AT 18Z ALONG I-35.   UPPER AIR ANALYSIS SUPPORTS SLOW
MIGRATION AND PHASING OF SYSTEM WITH VIGOROUS EARLY FALL SHORT WAVE NOW
IN WESTERN CANADA.  MARGINAL MOISTURE ALONG AND AHEAD OF BOUNDARY WITH
UPPER 50 TO LOWER 60 DEWPOINTS AHEAD OF LEE SIDE TROUGH.  18Z ANALYSIS
SUGGEST WEAK SFC WAVE TRYING TO PHASE WITH TWO UPPER SYSTEMS IN CENTRAL
KANSAS AND SHOULD BE THE FOCUS FOR PRECIPITATION EVOLUTION NEXT 24
HOURS.

...TEMPS AND INCREASING CLOUDS WITH POPS SATURDAY NEAR TERM ISSUE AND
THEN COOL DOWN WITH NEXT FRONT FORECAST CONCERNS...

.DIAGNOSIS AND DAYS 1-3...MODELS INITIALIZE AND VERIFY ONLY FAIR AS
NORMAL WITH MOISTURE AND QPF AT 18Z WITH ETA/AVN BLEND THE BEST
SOLUTION ADJUSTING FOR DECENT DEVELOPMENT LATER THIS PM AND EVENING
IN KANSAS.  TIMING SUPPORTS CLOUDS MOVING IN WEST TO EAST OVERNIGHT
LIMITING LOWS TO A TAD ABOVE GUIDANCE BLEND FOR A CHANGE AND WILL KEEP
DECAYING LIGHT RAIN AND SPRINKLES WEST SECTIONS AS BOTH SYSTEMS
APPROACH.  SATURDAY...WILL GO CATEGORICAL MOST AREAS WITH WEAK SFC LOW
MOVING ACROSS TO ALLOW NATURAL FOCUS FOR MORE PRECIPITATION TO MOVE AND
REDEVELOP DURING DAY MOST AREAS.  VERY MARGINAL INSTABILITY SUGGEST
MAINLY SHOWERS WITH ISOLATED STORMS WITH NO CHANCE FOR SEVERE UNLESS WE
GET A LOT MORE HEATING THAN EXPECTED.  HIGHS WITH PRE-FRONTAL HEATING 1-
2 CATEGORIES ABOVE CENTRAL AND SOUTHEAST SECTIONS.  KEEP EVENING SHOWERS
EAST SECTIONS AS SYSTEM PULLS EAST AND CLEARING AND MUCH COOLER...
ESPECIALLY NW SECTIONS.  MODELS PHASE AND NOW ACCURATELY REFLECT AMOUNT
OF COOLING WHICH PREVIOUS FORECASTS ALREADY INCORPORATED AND SO LITTLE
NEED TO MAKE MAJOR CHANGES THROUGH MONDAY WITH NICE AND CRISP EARLY
FALL CONDITIONS.  MAY SEE NEARLY BREEZY CONDITIONS SUNDAY AS STRONG CAA
KICKS IN AND LOTS OF SUNSHINE BUT WILL HOLD OFF PUTTING BREEZY WORDING
IN FOR NOW FOR LATER SHIFTS TO CONSIDER.

.EXTENDED (TUE-FRI)...LATEST MIX OF MEDIUM MODELS NOW ALSO FALLING IN
LINE WITH EARLIER DECISIONS OF GOOD WAA TUE/WED AHEAD OF NEXT SYSTEM
AND MORE MOIST CONDITIONS.  NEGATIVELY TILTED TROUGH SUGGESTED TO FAVOR
VIGOROUS UPPER TROUGH AND SYSTEM BY LATE WEEK WITH SHOWERS AND SOME
STORMS.  ANTICIPATE A HIGH CHANCE OF MAJOR CHANGES OF EVOLUTION OF THIS
SYSTEM NEXT COUPLE OF DAYS.  BEST ROUTE TO KEEP UNSETTLED CHANCE POPS
DUE TO PHASING ISSUES WED/THU WITH LIKELY WORDING PLAUSIBLE FOR NEXT FEW
SHIFTS TO SERIOUSLY CONSIDER.  RAINS WILL BE WELCOME AND SUBSEQUENT COOL
AIR SUGGEST CHANCE OF FROST BY NEXT WEEKEND SOME AREAS.

.DVN...
IA...NONE.
IL...NONE.
MO...NONE.

NICHOLS