[LeArc] Forecast Discussion : MLI@ 10/4/02 2:33:18 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 041940
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
230 PM CDT FRI OCT 4 2002

CHANGEABLE WX PATTERN FORTHCOMING (TYPICAL OF FALL). 

COLD FRONT EXITING FAR EASTERN ZONES WITH COOLER AND DRIER AIR INFILTRATING
REGION ON BLUSTERY WEST TO NORTHWEST WINDS. SHORTWAVE LIFTING
NORTHEAST FROM UPPER MIDWEST HAS ABSORBED REMNANTS OF LILI WITH MAIN PCPN BAND
SHIFTING QUICKLY THROUGH GREAT LAKES AND OHIO VALLEY. ISALLOBARIC
COMPONENT LIFTING NORTHEAST WITH SURFACE WAVE IN MN THUS STRONGEST WINDS TO
PASS NORTH...NONETHELESS BREEZY/WINDY CONDITIONS FOR A WHILE THIS EVE.
NEXT SYSTEM DIVING THROUGH B.C. AND ALBERTA CAN WITH 110+ KT JET. THIS ENERGY
IS EXPECTED TO COME ACROSS MIDWEST ON SUN BRINGING NEXT CHC OF RAIN. 

CONCERNS INCLUDE CLOUD TRENDS/WINDS AND IMPACTS ON LOWS TONIGHT...PCPN CHCS
WITH NEXT SYSTEM LATE SAT/SUN...THEN FROST/FREEZE POTENTIAL MON MORNING.

TONIGHT...GUSTY WEST/NORTHWEST WINDS TO SLOWLY RELAX AS RIDGE OF HIGH PRESSURE 
BUILDS IN. WIND GUSTS NEAR ADVISORY CRITERIA IN SOME LOCALES...AND 
EXPECT THAT TO CONTINUE NEXT COUPLE OF HOURS...BUT NOT WIDESPREAD ENOUGH 
FOR ADVISORY. WRAP-AROUND LOW CLOUDS TO GRADUALLY GIVE WAY TO CLEARING. 
TRAJECTORIES SUGGEST NORTHWEST MN SOURCE REGION WHERE MORNING LOWS WERE L/M40S.
GIVEN EXPECTED SLOW CLEARING/DECREASING WINDS AND WET GROUND WILL SIDE
TOWARD MAV/FWC BLEND SHAVING A DEG OR TWO...ESPECIALLY NORTH AND WESTERN ZONES.

SATURDAY...AFTER SUNSHINE TO START...EXPECT TO SEE CLOUDS INCREASE AS WARM 
ADVECTION STRENGTHENS IN PLAINS AHEAD OF ADVANCING SYSTEM. 
SURFACE HIGH WILL BE SHIFTING EAST WITH LLVL FLOWING BECOME SOUTHERLY...ALBEIT
LIGHT. TEMPS A BLEND OF MORE REALISTIC MAV/FWC GUIDANCE.

SATURDAY NIGHT...WITH WARM ADVECTION...CLOUDS AND SOUTH WINDS STAYED ABOVE
GUIDANCE ON MINS. TEMPS MAY ACTUALLY HOLD STEADY OR EVEN RISE
DEG OR TWO. CHC OF SHOWERS...MAINLY WEST OF MISSISSIPPI LATE...WITHIN BAND 
OF OMEGA AND THETA-E ADVECTION.

SUNDAY...SURFACE WAVE DEEPENS AS IT LIFTS NORTHEAST THROUGH GREAT LAKES
DRAGGING COLD FRONT THROUGH REGION EARLY ON. AVN REMAINS AGGRESSIVE
WITH MOISTURE AND PCPN CHCS. BASED ON DIFFLUENCE AND STRENGTH 
OF VORTICITY ADVECTION WILL INCREASE POPS INTO LIKELY CAT NORTH AND CONTINUE 
WITH JUST CHC POPS IN SOUTH. STEEP LAPSE RATES SUFFICIENT FOR CHC
THUNDER WITH HAIL POSSIBLE GIVEN COLD AIR ALOFT. BREEZY/WINDY CONDITIONS 
POST FRONTAL WITH FALLING TEMPERATURES. 

SUNDAY NIGHT/MONDAY...SURFACE RIDGE BUILDS INTO REGION THROUGH 12Z MON WITH
WINDS DIMINISHING AND SKIES CLEARING. TEMPS TO BOTTOM OUT IN THE 30S
WITH POTENTIAL FOR KILLING FROST AND FREEZE. SOME UNCERTAINTIES WITH REGARDS
TO WET GROUND. COOL AND DRY ON MONDAY WITH SURFACE RIDGE SHIFTING
SLOWLY EAST. 

EXTENDED (TUE-FRI)...
MEDIUM RANGE MODELS SUGGEST NEARLY ZONAL UPPER FLOW TO DOMINATE...WITH TEMPS
MODERATING TO NEAR OR SLIGHTLY ABOVE NORMAL. QUICK MOVING 
SYSTEM ON TUE...BUT MOISTURE SPARSE WITH SURFACE RIDGING INTO GULF OF MEXICO.
CURRENT FORECAST HAS MENTION OF CHC OF PCPN ALL ZONES AND WILL CONTINUE
MENTION TO AVOID FLIP FLOPPING. HOWEVER...THREAT IS LOW WITH
MAINLY SPRINKLES. MEX GUIDANCE FAVORED ALTHOUGH WENT ABOVE BY 1-2 CATS LATE 
WEEK. 

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