[LeArc] Forecast Discussion : MLI@ 5/29/2003 3:00:42 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 290759
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
300 AM CDT THU MAY 29 2003

LATEST SURFACE ANALYSIS INDICATING THAT THE SURFACE FRONT NOW WELL 
TO THE EAST OF THE CWA...WITH A RIDGE BUILDING IN.  UPPER LEVELS 
ALSO SHOWING THIS RIDGE BUILDING IN...WITH MODERATE NORTHWEST FLOW 
OVER IA/IL.  THE 250MB JET MAX COMING OVER THE TOP OF THE RIDGE IS 
DIVING SOUTH OVER MN AND IA...AS MUCH AS 105KTS.  

THE MAIN CONCERN THIS FORECAST INCLUDES THE TIMING AND PRECIP 
CHANCES OF THE FRONT TO MOVE THROUGH THE AREA ON FRIDAY...AND TEMPS 
NEXT FEW DAYS.

00Z MODELS APPEAR TO HAVE INITIALIZED REASONABLY WELL...WITH MUCH 
IMPROVED AGREEMENT ON THE FRIDAY FRONT PASSAGE OVER YESTERDAYS 
RUNS.  THERE HAS BEEN A BIT OF A SWITCH FROM THE 12Z RUNS IN THAT 
NOW THE ETA AND NGM ARE FASTER THAN THE AVN AND UKMET SOLUTIONS.  
THE SURFACE LOW POSITIONS ARE LESS DIFFERENT THAN THEY WERE AT 12Z 
ALSO.  AVN SEEMS TO HAVE THE BEST CONTINUITY FROM ITS 18Z RUN...AND 
THE ETA IS SIGNIFICANTLY FARTHER NORTH THAN THE 12Z RUN.  IN 
ALL...GENERALLY PREFER THE AVN RUN...THOUGH WOULD LIKE A FASTER 
VERSION OF IT AS I THINK THE UPPER LEVEL SHORT WAVE IS PROBABLY TOO 
STRONG AND A WEAKER WAVE WILL MOVE MORE QUICKLY THROUGH THE FLOW.

THE LATE THURSDAY NIGHT FRIDAY SYSTEM IS OF THE MOST CONCERN...AS 
THE TIMING OF THE FRONT WILL HAVE EVERYTHING TO DO WITH POSSIBLE 
SEVERE WEATHER FOR FRIDAY.  WEDNESDAYS FRONT CAME THROUGH KDVN 
AROUND 16Z...AND THE SEVERE WEATHER WAS ALL EAST OF OUR CWA.  THE 
TIMING OFF THE AVN FROM 00Z DOES NOT BRING THE FRONT THROUGH KDVN 
UNTIL AFTER 18Z...WITH THE ETA BRINGING IT IN CLOSE TO 18Z.  FOR NOW 
WILL STICK WITH HIGH CHANCE POPS...THOUGH PERHAPS BY DAY SHIFT THERE 
WILL BE ENOUGH CONSENSUS IN MODELS TO GO WITH LIKELY.  EVENT SHOULD 
BE SIMILAR TO WEDNESDAYS...AND WILL WORD HWO TO MATCH.  FRIDAY LATE 
AFTERNOON AND EVENING SHOULD BE WINDY LIKE WEDNESDAY...WITH HIGH 
LAPSE RATES IN THE LOWEST LAYERS...AND AND 30 TO 40 KT WINDS AT 
850MB. 

IN THE EXTENDED TIME RANGE...THE THE AVN DEPICTS WHAT LOOKS LIKE A 
WAA BAND ALONG WITH SOME 850-700MB MOISTURE THAT MAY MANAGE TO 
SQUEAK OUT SOME SHOWERS ON SUNDAY NIGHT.  ALSO...MONDAY MAY ALSO 
NEED PRECIP CHANCES AS A SURFACE FRONT MOVES SLOWLY TOWARDS AREA 
WITH PRECIP DEVELOPING IN THE WARM SECTOR.  FOR NOW ONLY THE LATEST 
AVN AND MRF INDICATING THIS...WITH PREVIOUS RUNS DRY AS WELL AS 
GOING FORECAST.  HAVE DECIDED TO THROW SOME 10 POPS INTO GRIDS...AND 
LATER SHIFTS CAN RE-EVALUATE THESE PRECIP CHANCES...THOUGH THINK 
THEY WOULD BE LOW CHANCES ANYWAY.

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

$$

LE