[LeArc] Forecast Discussion : MLI@ 10/21/02 3:02:04 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 212005
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
305 PM CDT MON OCT 21 2002

SURFACE COLD FRONT MAKING FAIRLY SLOW PROGRESS ACROSS IA...WITH ONLY 
MODERATE RISES TO ITS WEST.  SHOWERS AHEAD OF FRONT NOT ALL HITTING 
GROUND...LOTS OF VIRGA WITH ONLY A FEW REPORTS OF -SHRA.  LOTS OF 
LOW CLOUDS BEHIND FRONT...AS WELL AS BREEZY CONDITIONS WITH GUSTS TO 
OVER 20 KTS.   

BIG FORECAST CHALLENGE IS THE ONCOMING PRECIPITATION EVENT FOR LATE 
TUESDAY THROUGH THURSDAY...WITH LOTS OF MODEL UNCERTAINTY TO KEEP 
FORECASTER CONFIDENCE LOW...THOUGH BETTER THAN ON LAST 2 DAYS.  
OTHER FACTORS TO CONSIDER IS TEMPS AND AMOUNTS OF SUNSHINE TUESDAY.

12Z MODELS ARE IN BEST AGREEMENT YET ON THIS ONCOMING SYSTEM... 
THOUGH STILL HAVE ENOUGH DIFFERENCES TO MAKE THINGS TOUGH.  SYSTEM 
IS MAINLY AN OVERRUNNING EVENT...WITH SURFACE FEATURES WEAK LITTLE 
INVERTED SURFACE TROUGHS.  ETA FEATURES ARE GENERALLY FARTHER SOUTH 
THAN AVN FEATURES...WHICH ARE A LITTLE FARTHER SOUTH THAN ON 
PREVIOUS RUNS.  HAVE DECIDED TO MAINLY FOLLOW WHAT AVN HAS...THOUGH 
A SLIGHTLY MORE NORTHERN VERSION OF THE ETA SOLUTION WOULD BE VERY 
CLOSE TO AVN SOLUTION.  

TONIGHT LOW CLOUDS SHOULD MOVE IN BEHIND THE SURFACE FRONT...BUT 
APPEAR TO BE ERODING FROM THE SOUTHWEST AS MAIN SURFACE LOW PULLS 
OFF TO THE EAST.  WILL HAVE TO GO WITH A VERY LOW CHANGE IN LOW 
TEMPS ACROSS CWA TONIGHT...AS CLOUDS WILL KEEP TEMPS UP NORTH BUT IF 
THEY DON'T STAY IN THE SOUTHWEST WILL HAVE TO DROP LOWS THERE.  LOW 
LEVEL TEMPERATURE TRENDS WOULD IMPLY TEMPS IN THE LOW TO MID 30S.

TUESDAY SHOULD BE MOSTLY SUNNY ACROSS AREA...WITH TEMPS FAIRLY CLOSE 
TO A MAV/FWC BLEND. TUESDAY NIGHT SHOULD HAVE GRADUALLY INCREASING 
CLOUDS...WITH PRECIPITATION BEGINNING FAR SOUTHWEST BY SUNRISE.  
WEDNESDAY IS TOUGH.  CONFIDENCE IS FAIRLY HIGH THAT SOUTHWEST CWA 
WILL GET BEST CHANCE OF PRECIP...THOUGH NORTHEASTERN PARTS OF CWA 
ARE GETTING A LITTLE TOO FAR FROM THE ISENTROPIC LIFT...AS WELL AS 
ANY QG CONVERGENCE.  HAVE DROPPED POPS NORTH TO CHANCES.  FOLLOWING 
THE PARTIAL THICKNESSESS...STRAIGHT SNOW FAR NORTH MAY NEED TO BE 
TWEAKED A LITTLE...BUT WONT BE GOING FAR FROM GENERAL IDEA IN CURRENT 
FORECAST.

EXTENDED...FRI-MON
RELATIVELY QUIET PERIOD WITH SOME LINGERING PRECIP ON FRIDAY MORNING 
WITH THE HIGH BUILDING OVER THE HIGH PLAINS.  FRIDAY NIGHT LOOKS TO 
BE VERY CHILLY...WITH SURFACE RIDGE NEAR CWA.  ON SATURDAY A WEAK 
SURFACE FRONT IS IN VICINITY...BRINGING IN A RE-ENFORCING SHOT OF 
COLDER AIR.  THIS FRONT LOOKS KIND OF DRY FOR NOW.  SUNDAY A 
FRONT/BAROCLINIC ZONE SETS UP TO THE SOUTH OF THE CWA...WHICH COULD 
MANAGE TO GET SOME PRECIP INTO SOUTHERN ZONES.  BY MONDAY SYSTEM 
SHIFTS SOUTHEAST...SO DRY ALL AROUND.  BOTH DAYS NEED CLOUDY 
CONDITIONS WITH CLOUDS OVERRUNNING FROM SOUTH.  

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

LRE