[LeArc] Forecast Discussion : MLI@ 7/17/02 2:39:40 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 170740
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
240 AM CDT WED JUL 17 2002

BROAD UPPER LEVEL RIDGE REMAINS IN PLACE OVER THE CENTRAL US THIS 
MORNING...WITH THE WEAK LOW STILL SPINNING OVER MO. LOW HAS BEEN OF 
CONCERN LATELY...APPROACHING CLOSE ENOUGH SUCH THAT TSTMS HAVE BEEN 
A POSSIBILITY...BUT MOISTURE LACKING ON THE NORTH SIDE OF THE SHEAR 
ZONE ASSOCIATED WITH THE LOW. SOUTH OF THE SHEAR AXIS...PLENTY OF 
CONVECTION OBSERVED.  SOME SMALL TSTMS OBESERVED NEAR CENTER OF LOW 
SOUTHEAST OF MCI SEEM TO HAVE TRIGGERED OFF A WEAK SURFACE FRONT 
THERE.  ITS MAINLY A DEWPOINT CHANGE.  LARGE MCS MOVING OUT OF MT 
INTO ND SHOULD MOVE EAST THROUGH THE NIGHT...LIKELY ASSISTING IN 
STRENGTHENING THE SURFACE FRONT DEVELOPING THERE.  

MAIN CONCERNS THIS MORNING INCLUDE THE CHANCES OF CONVECTION TONIGHT 
AND AGAIN THURSDAY NIGHT.  TEMPS TODAY ALSO A CONCERN.

MODELS APPEAR TO HAVE INITIALIZED WELL...AND ARE BEGINNING TO LOOK 
BETTER AND MORE CONSISTENT IN HANDLING OF THE FRONT THURSDAY AND 
FRIDAY. WILL BE GOING WITH A BLEND OF THE AVN AND ETA...AS THERE ARE 
FEATURES OF EACH THAT LOOK GOOD AND HARD TO PIN DOWN WHICH IS BEST.  
SURFACE FRONT ON AVN THURSDAY AM SEEMS AS IF IT SHOULD BE STRONGER 
AND MORE LIKE THE ETA SOLUTION...CONSIDERING THE CONVECTION 
OCCURRING TO ITS NORTH AND OTHER THERMAL FEATURES.  THE AVN AND 
UKMET IN THE LATE THURSDAY FRIDAY TIME FRAME GET PROGRESSIVE WITH 
THE UPPER LOW...PHASING IT WITH THE MAIN FLOW AND PUSHING IT TO THE 
SOUTHEAST.  THE ETA DOES NOT DO THIS...HANGING THE LOW UP OVER 
SOUTHWEST MO ON THURSDAY NIGHT AND BY FRIDAY AM IS OVER OK.  THIS 
DIFFERENCE IS KEY ON THE POSITIONING OF THE SURFACE FRONT BY THIS 
TIME FRAME.  ETA KEEPS THE SURFACE FRONT ACROSS THE CWA FRIDAY 
AM...AND DOES NOT BRING THE FRONT AS FAR SOUTH AS THE AVN AND UKMET 
DO.  FOR NOW...PREFER THE AVN/UKMET SOLUTION FOR THESE LATTER 
PERIODS.

TODAY...CANT RULE OUT POPS IN FAR SOUTH...THOUGH THINK CHANCES ARE 
PRETTY SLIM SO WILL BE GOING WITH A 10 OR 20 POPS.  HIGHS ARE GOING 
TO BE TRICKY...BUT AM GOING COOLER THAN I DID YESTERDAY...WITH MORE 
CLOUDS THAN PREVIOUSLY THOUGHT...AND A LITTLE LESS WAA.  

TONIGHT...AGAIN CANT RULE OUT LOW POPS FAR SOUTH IN THE EVENING... 
THOUGH MAY HAVE TO WATCH OUT TO SEE IF THAT WAVE WILL BE FAR ENOUGH 
EAST TO POP OFF SOME MORE TSRA UNDER THE UPPER LOW CENTER. 

THURSDAY...LIKE NOTED ON DAY SHIFT...BEST CHANCES FOR PRECIP SHOULD 
BE FARTHER NORTH...WITH ONLY SOME LATE AFTERNOON TSRA SNEAKING INTO 
THE NORTH.  UPPER LOW SHOULD HAVE DROPPED FAR ENOUGH SOUTH SO CAN 
LEAVE POPS OUT OF SOUTH.  HIGH TEMPS SIMILAR TO TODAY.

THURSDAY NIGHT...BEST CHANCE OF POPS AS AN EARLY MCS MOVES THROUGH 
CWFA.  NO GREAT SURPRISE THAT WE ARE IN SLIGHT RISK...THOUGH THIS 
WILL DEPEND ON TIMING...AND WILL NOT METION IN PACKAGE FOR NOW.  
GOOD SWO MATERIAL.  

FRIDAY A QUESTION MARK AS HOW FAR SOUTH THE FRONT SHIFTS IS KEY ON 
HOW LONG PRECIP LASTS ACROSS FORECAST AREA.  FOR NOW HAVE GONE WITH 
A BLANKET CHANCE TRW WHICH CAN BE REFINED LATER.

EXTENDED...SAT-TUES
DONT EXPECT TO MAKE ANY CHANGES ATTM...THOUGH LATER SHIFTS WILL HAVE 
TO LOOK AT LATE SUNDAY PRECIP AS THIS SYSTEM IS MOVING A LITTLE 
FASTER THAN IT WAS ON PREVIOUS RUNS ACCORDING TO THE EXTENDED AVN.  

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

LRE