[LeArc] Forecast Discussion : MLI@ 6/9/2003 3:27:18 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 092020
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
315 PM CDT MON JUN 9 2003

MAIN FORECAST QUESTION WILL BE THE EXTENT OF CONVECTION AND THE 
POTENTIAL FOR SEVERE WEATHER TONIGHT.

SYNOPSIS-
THE LOCAL AREA IS BEGINNING TODAY UNDER THE INFLUENCE OF A HIGH 
PRESSURE RIDGE FROM MO THROUGH MN.  SFC LOW PRESSURE IS DEVELOPING 
OVER THE PANHANDLE OF NE...WITH A WARM FRONT STRETCHING EAST ACROSS 
CENTRAL NE THROUGH WESTERN MO.  THIS FRONT WILL BE THE FOCUS FOR 
INTENSE CONVECTION DURING THE NEXT 24 HOURS. ALOFT...DEEP MOISTURE 
IS FLOWING NORTH OVER THE PLAINS...WITH 850MB DEWPOINTS OF 15 TO 18C 
LIFTING INTO OK AT 12Z. THE TRIGGER FOR CONVECTION THIS EVENING AND 
OVERNIGHT WILL BE A MID LEVEL SHORT WAVE TROF MOVING SOUTHEAST 
ACROSS MT THROUGH SOUTHERN MANITOBA AT 12Z. ANOTHER IMPRESSIVE SHORT 
WAVE TROF IS LOCATED ALONG THE COAST OF BRITISH COLUMBIA...AND WILL 
LIKELY AFFECT THE MIDWESTS WEATHER BY MID/LATE WEEK.

SHORT TERM- (TONIGHT AND TUESDAY)
GRADUAL INCREASE IN CLOUD COVER IS EXPECTED THIS EVENING AS STORMS 
ALONG THE WARM FRONT FIRE WELL WEST OF THE CWA. STRONG TO SEVERE 
STORMS WILL EVOLVE INTO LINEAR CONVECTION ACROSS CENTRAL IOWA THIS 
EVENING.  CONCERN FOR SEVERE WEATHER STILL EXISTS AS THE POTENTIAL 
FOR DAMAGING WINDS GUSTS WILL BE PRESENT ALONG THE RAPIDLY 
PROPAGATING COLD POOL.  THE THREAT APPEARS GREATEST IN THE SOUTHERN 
CWA...WHERE 850MB FLOW WILL FEED BETTER MOISTURE INTO STORMS. 
CURRENT FORECAST OF LATE NIGHT THUNDERSTORMS SEEMS ON TARGET AND 
WILL ONLY TWEAK POPS SLIGHTLY FOR A WEST TO EAST GRADIENT.  
THE MAIN SYNOPTIC FRONT IS EXPECTED TO HANG UP OVER THE CENTRAL AND 
SOUTHERN CWA EARLY TUESDAY.  SCATTERED AFTERNOON CONVECTION WILL 
LIKELY FIRE ALONG THIS FRONT.  A LIMITING FACTOR WILL BE IF THE 
OUTFLOW FROM TONIGHTS STORMS WILL FOCUS THE MAJORITY OF THE 
CONVECTION SOUTH INTO MISSOURI AND SOUTHERN ILLINOIS.  DUE TO THIS 
POSSIBILITY...WILL LOWER TUESDAYS POPS TO CHANCE ACROSS THE NORTH 
AND CENTRAL...AND CONTINUE LIKELY POPS IN THE SOUTH.  

BREAK IN THE RAIN TUESDAY NIGHT THROUGH WEDNESDAY WITH FRONT TO 
OUR SOUTH AND NORTHEAST SURFACE FLOW FROM HIGH IN THE 
GREAT LAKES. 

RENEWED CONVECTION EXPECTED ALONG THE FRONT WEDNESDAY NIGHT WITH
ENERGY EJECTING FROM THE ROCKIES. THIS CONVECTIVE COMPLEX COULD 
BRUSH THE SOUTH DURING THE MORNING. MODELS SUGGEST PROTECTING RIDGE 
TO SHIFT EAST WITH ENERGY APPROACHING SO HAVE INCLUDED
POPS ENTIRE AREA THURS AFTERNOON...AND HAVE KEPT POPS THURS NIGHT.

EXTENDED- (FRIDAY THROUGH MONDAY)
INTERESTING AND TRICKY FORECAST WITH DETAILS DEPENDENT ON LOCATION 
OF LAKE ENHANCED QUASI-STATIONARY FRONTAL ZONE. FRONT WILL
BE THE FOCUS FOR SEVERAL CONVECTIVE CLUSTERS AND EXCESSIVE RAINS...WITH
ANY DRIFT NORTH OR SOUTH FROM INTERACTION WITH OUTFLOWS 
EFFECTIVELY SHIFTING THE THREAT AREA. GAINING CONFIDENCE THAT BY LATE
IN THE WEEKEND SIGNIFICANT FLOODING WILL BE IMPACTING SOME AREAS IN 
THE MIDWEST. THE MAIN QUESTION REMAINS LOCATION...WHICH WILL
BE DETERMINED BY MESOSCALE FEATURES UNRESOLVED THIS FAR OUT. 
LEANING TOWARD BLEND OF UKMET AND ECMWF...WHICH WITH NORTHERN TREND 
TO FRONTAL POSITION SUGGESTS THAT SOUTHERN SECTIONS OF CWA ARE MOST 
AT RISK ATTIM FOR SEEING EXCESSIVE RAINS WITH ONE OR TWO MCS/S INTO 
SATURDAY. WILL ISSUE ESF HIGHLIGHTING POTENTIAL. FRONT WILL FEATURE 
SEASONABLE AND COMFORTABLE CONDITIONS TO THE NORTH...WITH WARM AND 
MUGGY PREVAILING SOUTH. 

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

$$

ERVIN/MCCLURE