[LeArc] Forecast Discussion : MLI@ 5/31/2002 2:52:47 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 310747
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
245 AM CDT FRI MAY 31 2002

PLENTY OF CONCERNS INCLUDING TEMPS AND PCPN CHCS NEXT SEVERAL DAYS ALONG
WITH POTENTIAL FOR HEAVY RAIN AND SEVERE WX.

WEAK FRONT/TROUGH AT 06Z EXTENDED FROM SOUTHWEST WI THROUGH CENTRAL IA ALONG
A KPDC-KALO-KDSM LINE. MODELS IN GENERAL AGREEMENT ON SHIFTING
BOUNDARY INTO VICINITY OF FAR SOUTHERN IA/NORTHERN MO/CENTRAL IL BY EVE THEN
BECOMING NEARLY STATIONARY. THIS BOUNDARY WILL BE THE FOCUS 
FOR MAINLY NOCTURNAL CONVECTION THROUGH SUN...AS IT LURKS NEARBY.

IN NEAR TERM...FRONT TO SAG SOUTH ACROSS MUCH OF THE REGION...RESULTING IN
LESS HUMID CONDITIONS. CONCERN IS WITH PCPN CHCS...BELIEVE WITH
AFTN HEATING AND ENOUGH LOW LEVEL CONVERGENCE COULD POP SOME CONVECTION IN
SOUTHERN ZONES. ALSO...WATCHING MID LEVEL CLOUDS AND 
ASSOCIATED SHRA/TSRA OVER NORTHERN PLAINS WITH SHORTWAVE AND MID LEVEL WARM 
ADVECTION. EXPECT THIS ACTIVITY TO WEAKEN AS IT PROPAGATES E/SE.
SHORTWAVE AND WARMING WILL SHIFT IN OUR DIRECTION THIS AFTN BRINGING INCREASE
IN MID LEVEL CLOUDS. GIVEN EXTENT OF DRYING IN LOW LEVELS...NOT THINKING 
MUCH PCPN REACHING GROUND...BUT CAN/T RULE OUT SPRINKLES OR FEW LIGHT SHOWERS.

TONIGHT...BOUNDARY STALLED ACROSS THE SOUTHERN ZONES WITH MODELS INDICATING
PRETTY DECENT MOISTURE ADVECTION ON NOSE OF 30-35 KT LLJ.
MAIN FOCUS LOOKS TO BE IN WEST/SOUTHWEST IA WITH THETA-E ADVECTION AND LLJ.
CONVECTION (POSSIBLE MCS) THEN EXPECTED TO PROPAGATE E/SE ALONG AND
NORTH OF BOUNDARY...AFFECTING MAINLY SOUTHERN HALF OF CWA...THUS LIKELY POPS
IN CURRENT FORECAST IN THE SOUTH LOOK GOOD. 

SAT-SUN...FORECAST MORE COMPLEX...AS ANY OUTFLOW BOUNDARIES FROM MCC OR MCS
ACTIVITY TEND TO SUPPRESS FRONTAL ZONE FURTHER SOUTH...BUT AVN CONTINUES 
TO BE AGGRESSIVE IN LIFTING FRONT WELL NORTH ON SUN. 
SIDING TOWARD FURTHER SOUTH PLACEMENT OF ETA AND UKMET...WHICH SHOW GREAT LAKES
HIGH AND TYPICAL LAKE EFFECT POINTING TOWARD COOLER TEMPS.
 
AS PREVIOUS SHIFT MENTIONED...OVERALL PATTERN WITH ZONAL JET AND E-W FRONTAL
ZONE FAVORABLE FOR HEAVY RAIN AND SOME SEVERE WX NEXT FEW DAYS.
WILL HIGHLIGHT IN SIG WEATHER OUTLOOK AND ALSO REISSUE ESF HIGHLIGHTING
HEAVY RAIN POTENTIAL. 

AS FOR TEMPS...TODAY SIDING TOWARD WARMER FWC BASED ON EXTENT OF 
POST FRONTAL WARMING IN PLAINS AND UPPER MIDWEST YESTERDAY...WHERE MERCURY
TOPPED OUT NEAR 90 DEGS MANY AREAS. SFC PARCEL TRAJECTORIES POINT TO
STAGNANT PATTERN WITH TEMPS TODAY SIMILAR TO YESTERDAY AND EVEN FEW DEGS
WARMER WITH DEEP LAYER MIXING INDICATED PER ETA BUFKIT SOUNDINGS.
BELIEVE 90 DEGS GOOD BET SOME AREAS CENTRAL AND SOUTHERN ZONES!
FURTHER OUT WILL LEAN TOWARD BLEND OF MAV/FWC GUIDANCE MAKING NECESSARY TWEEKS
BASED ON CLOUD COVER AND PCPN COVERAGE. 

LOOKING BEYOND...AVN SUGGESTS PCPN LIKELY MON WITH SFC WAVE ALONG FRONTAL
ZONE...AND AGAIN LIKELY LATE TUE WITH INVERTED TROUGH RESULTING
FROM COLD AIR DAMMING LEE OF ROCKIES. WON/T MAKE CHANGES ATTIM...BUT WILL
PASS ON TO DAY CREW TO RE-EVALUATE. 

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

MCCLURE