[LeArc] Forecast Discussion : MLI@ 7/14/2003 4:13:25 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 142100
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
400 PM CDT MON JUL 14 2003

RUNNING A BIT BEHIND...SO WILL GET RIGHT TO IT. FOCUS FOR SURFACE 
BASED CONVECTIVE DEVELOPMENT IS IN FAR SOUTHEAST SD...NORTHWEST IA AND
SOUTHWEST MN WHERE RECENT VISIBLE SATELLITE PICS SHOW CU FIELD 
BECOMING BETTER ORGANIZED IN THIS REGION WHERE MOISTURE CONVERGENCE
IS MAXIMIZED. STRONG CAP (+15C OMA) KEEPING LID ON THINGS FOR THE 
TIME BEING...THOUGH LATEST LAPS DATA INDICATES CIN IS LOWERING 
THUS CAP IS WEAKENING...SO CONVECTIVE DEVELOPMENT MAY BE SOON WITHIN 
THE NEXT 1-2 HRS. COUPLE OF SEVERE MODES ANTICIPATED WITH 
SUPERCELLS INITIALLY...FOLLOWED BY BOW ECHO WITH DAMAGING STRAIGHT
LINE WINDS. PROPAGATION OF BOW ECHO WILL TEND TO BE DUE SOUTH 
OR POSSIBLY A LITTLE EAST OF SOUTH FOLLOWING BEST LLVL INFLOW AND 
AXIS OF BEST MOISTURE AND INSTABILITY. THUS...SEVERE POTENTIAL APPEARS
TO BE LIMITED TO OUR WESTERN COUNTIES LATER THIS EVENING.
NICHOLS BOUNDARY LAYER ENERGY POTENTIAL (BLEP) CALCULATIONS SUGGEST
MARGINAL EVENT BASED ON T/TD OF 76/70 WITH MAX STRAIGHT LINE WINDS 
OF 44 KTS. ELSEWHERE...NOT ENOUGH SUPPORT FOR SEVERE WITH
BEST FORCING TO OUR NORTH WITH VIGOROUS 100-120 KT JET ADVANCING THROUGH
THE UPPER MIDWEST AND GREAT LAKES. DIFFLUENCE...AMPLE LLVL MOISTURE
AND FRONTAL CONVERGENCE SHOULD BE ENOUGH TO TRIGGER AT LEAST 
SCATTERED SHOWERS AND THUNDERSTORMS OVER THE ENTIRE CWA. BEST COVERAGE
THOUGH MAY END UP BEING WEST OF THE MISSISSIPPI. 
FOR NOW...KEPT LIKELY POPS ENTIRE CWA...BUT WOULD NOT BE SURPRISED TO
SEE LESS COVERAGE/WEAKENING TREND TO ACTIVITY AS IT MOVES INTO 
THE EASTERN ZONES LATE TONIGHT WHERE AIRMASS EXPECTED TO BE NOT AS 
UNSTABLE.  

TUESDAY...FRONT SWINGS THROUGH IN THE MORNING. KEPT LOW POPS IN 
UNTIL MID MORNING FOR AREAS BASICALLY ALONG AND EAST OF THE 
MISSISSIPPI. MODELS INDICATE SUBSIDENCE AND STRONG DRYING 
AND THIS LOOKS REASONABLE GIVEN THE POST FRONTAL SUNNY SKIES CURRENTLY
FOUND IN WESTERN SD AND WESTERN NE. TEMPS BEHIND THE FRONT
GENERALLY IN L/M 80S...THUS GUIDANCE LOOKS REASONABLE AND TOOK A BLEND
THOUGH FAVOR FWC GIVEN AMOUNT OF DRYING. ALSO...WINDS ARE GUSTING
TO AROUND 25 KTS BEHIND THE FRONT. IFPS GENERATED 10 TO 20 MPH
BUT WAS WANTING MORE OF A BREEZY 15 TO 25 MPH WITH GUSTS TO 30 MPH.
MID CREW WILL NEED TO TAKE A LOOK AT THIS. 

HIGH THEN MOVES OVERHEAD TUESDAY NIGHT AND EARLY WEDNESDAY PROVIDING 
TRANQUIL CONDITIONS. STAY AT OR JUST BELOW LOW END OF GUIDANCE FOR 
MINS WEDNESDAY MORNING. FORECAST CONCERN THEN SHIFTS TO WHEN TO 
INTRODUCE NEXT CHANCE OF PCPN. HIGH PRESSURE WILL RETREAT ON 
WEDNESDAY ALLOWING RETURN FLOW TO DEVELOP. FRONT WILL BE 
LOOKING TO RETURN BACK NORTH WITH 12Z UKMET FAIRLY AGGRESSIVE IN 
GENERATING QPF WEDNESDAY AFTERNOON AND EVENING. ETA AND GFS ARE 
SLOWER...AND FOLLOWED DUE TO STRENGTH OF THE HIGH...THOUGH THIS WILL 
NEED TO BE WATCHED. HAVE POPS IN FOR OVERNIGHT WEDNESDAY.  
 
THURSDAY...LLVL EAST WINDS...PRECIPITATION (POTENTIAL MCS) AND 
CLOUDS SUGGEST TEMPS WILL STRUGGLE. SEEN THIS SCENARIO PLAYED OUT 
MANY TIMES AND KNOWING THIS...GUIDANCE IS AT LEAST 1-2 CATS 
TOO WARM. LOWERED TEMPS AND BELIEVE I MAY NOT BE COOL ENOUGH...BUT 
LIMITED BY NDFD REQUIREMENTS.  

EXTENDED...FRI-MON
PATTERN REMAINS ACTIVE WITH UPPER FLOW GENERALLY WEST/NORTHWEST. 
GREAT LAKES HIGH RETREATS ON FRI WITH RETURN FLOW AHEAD
OF NEXT FRONTAL SYSTEM SLATED FOR LATE FRI-EARLY SAT. WILL CONTINUE
CHC POPS DURING THIS TIMEFRAME. NEXT SYSTEM EARLY NEXT WEEK WITH
CHC PCPN. TEMPS WILL BE CHALLENGING. 

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

$$

05