[LeArc] Forecast Discussion : MLI@ 7/12/2003 2:15:30 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 121911
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
205 PM CDT SAT JUL 12 2003

VERY LITTLE 12Z MODEL DATA TO PERUSE DUE TO COMMS OUTAGE IN 
WASHINGTON DC. 

18Z SURFACE ANALYSIS SHOWS HIGH PRESSURE OVER NORTHERN NE WITH
A FRONTAL ZONE DRAPED FROM THE SOUTHERN PLAINS INTO THE
OHIO VALLEY. ALOFT...NORTHWEST FLOW PERSISTS. WATER VAPOR PICS
SHOW A SHORTWAVE SHEARING WHILE DIVING SOUTHEAST FROM SOUTHERN 
MANITOBA INTO MN. 
 
TONIGHT...
SURFACE HIGH MOVES OVERHEAD WITH IDEAL RADIATIONAL COOLING SETUP
WITH CLEAR SKIES AND LIGHT WINDS. WILL BE LOWERING CURRENT
MINS LEANING HEAVILY TOWARD OBSERVED MINS THIS MORNING BENEATH
HIGH CENTER IN NE WHICH WERE IN THE M/U 50S. RECORDS 
LOOK SAFE...THOUGH COULD BE WITHIN FEW 3-4 DEGS AT BRL (53 IN 1975 
AND PREVIOUS) AND DBQ (51 IN 1975 AND PREVIOUS).

SUNDAY...
AFWA MM5 MODEL...REPLACING THE GFS DUE TO COMMS PROBLEMS...BRUSHING 
CWA WITH VERY LIGHT QPF. HOWEVER...DON/T SEE SUFFICIENT 
FORCING TO INTRODUCE POPS. MUCH LIKE TODAY...ENOUGH INSTABILITY WITH 
FAIRLY STEEP LAPSE RATES...BUT LACKING A TRIGGER.
CAN/T RULE OUT AN ISOLATED SHOWER MID TO LATE AFTERNOON BUT COVERAGE 
NOT ENOUGH TO WARRANT MENTION IN ZONES. NOT MUCH THERMAL
CHANGE EXCEPT SLIGHT WARMING IN THE LOW LEVELS...SO WILL GO WITH
PERSISTENCE PLUS 1-2 DEGS. 

SUNDAY NIGHT AND MONDAY...
SURFACE HIGH SHIFTS EAST EARLY ON WITH RETURN FLOW DEVELOPING
WITH INCREASE IN HUMIDITY. MEANWHILE...UPPER LEVEL RIDGE 
BUILDS OVERHEAD RESULTING IN WARMER TEMPS. 

MONDAY NIGHT AND TUESDAY...
WX GETS INTERESTING WITH FRONTAL ZONE SAGGING SOUTH ACROSS THE
AREA. PARAMETERS IN PLACE FOR MCS DEVELOPING TO OUR NORTHWEST 
MONDAY EVE WITH WITH LLVL THICKNESS SUPPORTIVE OF PROPAGATION INTO 
CWA AFTER MIDNIGHT. POPS ARE A BIT OF A TOUGH CALL. DON/T WANT 
TO ADVERTISE LIKELY POPS IN BOTH PERIODS. WILL FOLLOW PREVIOUS SHIFTS
LEAD AND HIT POPS HARDEST NORTH AND WEST MONDAY NIGHT.
THEN HIT THE CENTRAL AND SOUTH HARDEST ON TUE GIVEN PROXIMITY OF
FRONTAL ZONE AND JET SUPPORT WITH RIGHT ENTRANCE REGION 
COMING INTO PLAY. 

EXTENDED (WED-SAT)...DUE TO LACK OF NEW DATA...FEW CHANGES MADE. 
CONCERNS FOCUSED WITH TEMPS MID TO LATE WEEK WITH 
CANADIAN HIGH DROPPING THROUGH THE GREAT LAKES. THEN ATTENTION
SHIFTS TO PCPN CHCS LATE IN EXTENDED. RETURN FLOW 
DEVELOPS LATE FRI-SAT AHEAD OF FRONTAL SYSTEM IN THE PLAINS. HAVE 
KEPT SAT DRY ATTIM...THOUGH POTENTIAL FOR MCS DEVELOPMENT 
ALONG FRONT PROPAGATING TOWARD CWA LATE SAT NIGHT. NEXT FEW SHIFTS 
WILL WANT TO RE-EVALUATE. 

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

$$

05