[LeArc] Forecast Discussion : MLI@ 10/28/02 2:27:48 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 280837
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
236 AM CST MON OCT 28 2002

REPORTS INDICATING THAT LIGHT SNOW...WITH VERY LIGHT ACCUMULATIONS 
...FALLING ACROSS THE NORTHERN PORTIONS OF THE CWA...ALONG AND NORTH 
OF HIGHWAY 20.  SOUTH OF THERE TO ALONG HIGHWAY 30 PRECIPITATION IS 
MIXED RAIN AND SNOW...AND THEN ALL RAIN FROM THERE SOUTH.  EARLIER 
THIS EVENING THE MIXED SNOW EXTENDED AS FAR SOUTH AS INTERSTATE 80.  
WITH BACK EDGE OF PRECIPITATION BAND NOW TO INTERSTATE 35...AND 
PROGRESSING SLOWLY EAST.  AT THIS RATE...BACK EDGE OF PRECIP WILL 
APPROACH WESTERN FRINGE OF CWA AROUND 11Z...AND WILL HAVE MOVED EAST 
OF CWA BY 15Z.  THE BACK EDGE OF THE PRECIP ALSO LINES UP WITH THE 
WEAK VORT MAX MOVING ACROSS THE STATE...WHICH SUPPORTS A SLIGHTLY 
FASTER VERSION OF THIS TIMING...THOUGH NOT TOO DIFFERENT.  WILL 
CHECK THESE TRENDS AGAIN BEFORE ISSUANCE.  

MAIN FORECAST CONCERN THIS PACKAGE ARE THE PRECIPITATION CHANCES AND 
THE TYPE NOW THROUGH WEDNESDAY...WITH ACCOMPANYING CONCERNS OVER 
POSSIBLE SNOW ACCUMULATIONS AND OTHER WINTER WEATHER HAZARDS.

00Z MODELS STILL DISPLAYING ENOUGH DIFFERENCES TO KEEP CONFIDENCE IN 
TUESDAY AND WEDNESDAY FORECAST RELATIVELY LOW...WITH THE MOST OF THE 
DIFFERENCES IN THE LOW AND MID LEVELS.  MOST OBVIOUS DIFFERENCE IS 
WITH THE SURFACE LOW.  THERE IS ONLY A HINT OF ONE ON THE AVN NEAR 
KEOK...THE UKMET IS SIMILAR BUT FURTHER SOUTH IN SOUTH CENTRAL 
MO...AND THE MUCH STRONGER...MUCH FURTHER SOUTH ETA POSITIONED ALONG 
THE AR/OK BORDER.  THIS MAKES A BIG DIFFERENCE IN WHERE THE 
PRECIPITATION SHOULD LAY OUT...WITH THE ETA KEEPING MOST OF THE LIFT 
AND MOISTURE ACROSS MISSOURI.  THE AVN IS THE FARTHEST 
NORTH...RUNNING BEST LIFT ACROSS NORTHERN HALF OF IA.  UKMET IS IN 
BETWEEN.  EXTRAPOLATION OF NGM SEEMS TO INDICATE THAT IT WOULD BE 
CLOSER TO THE ETA SOLUTION.  

TODAY ANY LINGERING RAIN/SNOW SHOULD TAPER OFF TO DRIZZLE OR 
FLURRIES DURING THE MORNING.  DESPITE DRIER AIR MOVING IN FROM THE 
EAST AT THE SURFACE...DO NOT THINK DRIZZLE CHANCES WILL END AS LIGHT 
ISENTROPIC LIFT CONTINUES THROUGH THE DAY AND INTO THE EVENING.  
THIS CUTS OFF THIS EVENING AND PRECIP CHANCES FOR TONIGHT SHOULD BE 
NIL...EVEN IF CLOUDS DO NOT DISSIPATE.  TEMPERATURES IN THE CLOUDS 
SHOULD BE ON THE COOL SIDE...AND WILL GO WITH A BLEND OF MAV AND FWC 
TODAY. 

TUESDAY THE QUESTION IS IF BEING BRACKETED BY TWO SYSTEMS...HOW MUCH 
PRECIPITATION CAN MAKE IT INTO CWA.  AS 00Z MODELS ARE FAIRLY 
CONSISTENT IN BRINGING PRECIP INTO SOUTHEASTERN CWA...SO WILL GO 
WITH LOW LIKELY POPS THERE...AND LEAVE CHANCE POPS FOR THE REST OF 
THE CWA.  TEMPS IN CLOUDS WILL BE ON THE CHILLY SIDE...AND WILL 
RANGE TEMPS FROM THE MID 40S TO AROUND 50.  

TUESDAY NIGHT THE PRECIP ENDS AGAIN FOR CWA AS THE ATMOSPHERE BREWS 
UP THE WEDNESDAY/THURSDAY SYSTEM.  AS CLOUDS DO NOT CLEAR OUT TEMPS 
AGAIN WILL HAVE LOW DIURNAL RANGE AND WILL STICK CLOSE TO MID 30 TO 
NEAR 40 IN GOING FORECAST.

WEDNESDAY IS THE BIG STORY...WITH THE SNOW QUESTION THE MAIN 
CONCERN.  AS THE MODELS CANNOT AGREE ON THE EVENTUAL TRACK JUST 
YET...WITH STAY FAIRLY CLOSE TO GOING FORECAST FOR CONSISTENCYS 
SAKE.  LATER SHIFTS WILL HAVE TO SEE ABOUT REFINING THIS PERIOD AS 
MODELS COME CLOSER TO A CONSENSUS.  

EXTENDED...THU-SUN
WITH COLD AIR POURING INTO THE CWA FROM THE NORTHWEST...AM RELUCTANT 
TO CLEAR CLOUDS TOO SOON WITH LINGERING CYCLONIC FLOW...AND PLENTY 
OF LINGERING LOW TO MID LEVEL MOISTURE.  WILL INCREASE CLOUDS ON 
THURSDAY...AND RAISE TEMPS A LITTLE FRIDAY NIGHT AND THURSDAY.  WITH 
500 MB COLD POOL MOVING ACROSS CWA FRIDAY...SHOULD BE PLENTY OF 
CUMULUS DURING THE DAY SO WILL INCREASE CLOUDS ON THIS DAY ALSO.  NO 
CHANGES EXPECTED TO SATURDAY AND SUNDAY...WITH DEFINETELY CHILLY 
TEMPS ON TAP...WITH THE ACTUAL SURFACE RIDGE BUILDING IN NICELY.

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

LRE