[LeArc] Forecast Discussion : MLI@ 10/28/02 2:13:46 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 282023
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
140 PM CST MON OCT 28 2002

OVERRUNNING ENVIRONMENT LOCKED IN WITH SOUTHWEST UPPER FLOW AND 
LLVL E WINDS...RESULTING IN ANOTHER DREARY DAY. ABUNDANT LLVL MOISTURE WITH
WEAK ISENTROPIC LIFT GENERATING WEAK PCPN (--RA/DZ). 
WATER VAPOR AND 12Z UPPER AIR ANALYSIS SHOW SHORTWAVE EJECTING OUT THROUGH
TX/OK PANHANDLES WITH ASSOCIATED PCPN SHIELD MOVING NORTHEAST
THROUGH OK. THIS WILL BE INITIAL FORECAST CONCERN. HOWEVER...MAIN FOCUS IS WITH
ENERGY DIVING SOUTH THROUGH NORTHERN ROCKIES WITH UPPER TROUGH
DROPPING SOUTH FROM BC INTO PACIFIC NORTHWEST. RESULTANT STORM SYSTEM...
TIMING OF COLD AIR...AND POTENTIAL FOR ACCUMULATING SNOW AND HIGHLIGHTS 
OF GREATEST CONCERN MIDWEEK FOLLOWED WITH NEAR RECORD TO RECORD COLD LATE WEEK. 

NEAR TERM...WILL FOLLOW NOWCAST TOOLS WITH INPUT FROM GFS/ETA/UKMET BLEND
AS RUC CLUELESS WITH ONGOING PCPN OVER SOUTHERN PLAINS.
SHORTWAVE TO EJECT E/NE FROM SOUTHERN PLAINS THROUGH LOWER MISSISSIPPI
VALLEY NEXT 24 HOURS. BULK OF FORCING TO PASS JUST SOUTH OF CWA...BUT CLOSE 
ENOUGH TO WARRANT LIKELY POPS IN THE S/E WITH CHC POPS CENTRAL 
AND LITTLE IN WAY OF PCPN IN THE N/NW ASIDE FROM --RA/DZ WITH WEAK ISENTROPIC
LIFT. LOWS GENERALLY AT OR ABOVE WARM END OF GUIDANCE WITH CLOUDS
LIMITING DROPOFF. SHORTWAVE PULLS EAST TUE MORNING AND WILL DIMINISH PCPN
TO JUST MENTION OF DZ/--RA WITH WEAK ISENTROPIC ASCENT. 
WITH NEUTRAL THERMAL ADVECTION WILL SIDE WITH MAXES SIMILAR TO THOSE OF TODAY. 

WED/THU BRINGS WELL ADVERTISED SYSTEM...WITH FORECAST CHALLENGING DUE TO
MODEL DIFFERENCES STILL YET. SYSTEM SHOULD BE BETTER SAMPLED 
FOR 18Z AND DEFINITELY 00Z MODEL RUNS...SO SHOULD HAVE EXCELLENT IDEA ON
SCENARIO TONIGHT. WHAT THE MODELS DO SEEM TO AGREE ON IS SLOWING WAVE 
AND ARRIVAL OF COLD AIR. MODELS ALSO ADVERTISE MORE CONFLUENT FLOW OVERHEAD AND 
TO THE EAST...THUS SUGGESTING WAVE WOULD DAMPEN AS IT MOVES FROM PLAINS 
INTO MID MISSISSIPPI VALLEY. STRONG COLD ADVECTION NOT ADVERTISED 
UNTIL WED NIGHT AND THU WITH SECOND AND MORE SIGNIFICANT SURGE SEEPING 
DOWN FROM THE NORTHLAND LATE WEEK. OVERALL COOLING INITIALLY ON WED WILL COME 
MAINLY FROM EVAPORATIVE PROCESSES WITH AID OF LLVL NE FLOW.
ETA SHOWS H925 TEMPS FROM 0.5C TO NEARLY 3.0C BY 00Z THU...WITH GUIDANCE
GENERALLY IN THE 40S FOR MAXES. OVERALL MAY NEED TO SLOW CHANGEOVER TO SNOW
AND BUMP UP TEMPS JUST A BIT FROM GOING FORECAST...BUT WILL MAKE 
FINAL DECISION AFTER LOOKING AT 18Z MODEL RUNS. MODELS SUGGEST THAT BULK 
OF SNOW TO OCCUR WED NIGHT AND THU WITH COLD ADVECTION WHERE SEVERAL 
INCHES NOT OUT OF QUESTION.  

EXTENDED (FRI-MON)...
UPPER TROUGH AND VERY COLD TEMPS (-13C TO -16C) SUPPORTS CONTINUING
MENTION OF FLURRIES ON FRI. UNSEASONABLY COLD AND LARGE ARCTIC HIGH SETTLES 
INTO REGION BY SAT...WITH NEAR RECORD TO RECORD COLD. 
UPPER FLOW REMAINS NORTHWEST WITH MODELS HINTING AT NEXT SYSTEM ARRIVING 
LATE SUN-MON TIMEFRAME. WARMUP TO OCCUR AHEAD OF SYSTEM WITH
ANY PCPN EXPECTED TO BE RAIN UNTIL SYSTEM PASSES AND BRINGS NEXT SHOT
OF COLDER AIR. WINTER IS ARRIVING!

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