[LeArc] Forecast Discussion : MLI@ 3/21/03 2:29:01 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 212037
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
230 PM CST FRI MAR 21 2003

MORNING ANALYSIS PLACED H5 LOW OVER NRN WISCONSIN WITH 18Z POSITION 
OF SURFACE LOW OVER NRN LAKE MICHIGAN.  BROAD/DEEP CYCLONIC FLOW 
AROUND LOW WAS GENERATING LARGE AREA OF SC...COVEREING ALL BUT THE 
EXTREME SOUTHERN COUNTIES OF CWA.  NO SIGNIFICANT DIFFERENCES WERE 
NOTED IN THE MODELS AS THEY MOVE THE H5 LOW QUICKLY E TONIGHT AND 
SATURDAY AND DEVELOP A NEARLY ZONAL FLOW OVER THE NRN U.S. INTO 
SUNDAY.  MAIN CONCERN IN THE SHORT TERM WILL BE THE CLOUD TRENDS 
TONIGHT AND SATURDAY AND RESULTING IMPACT ON TEMPS.

NO CLEAR CUT CHOICE OF MODEL SOLUTIONS FOR THE NEXT 48 HOURS. 
ETA/GFS BOTH KEEP CYLCLONIC FLOW AND HIGHER RH VALUES OVER NRN HALF 
OF CWA THROUGH 18Z SATURDAY.  WILL GENERALLY FOLLOW THIS 
TREND...WITH PESSIMISTIC CLOUD FCST OVER NERN THIRD OF CWA THROUGH 
SATURDAY.  CU'Y NATURE OF CLOUDS ON VIS IMAGES THIS AFTERNOON 
SUGGEST THAT CLOUDS OVER SOUTHERN COUNTIES MORE DIURNAL AND WILL 
DISSIPATE SHORTLY AFTER SUNSET.  LOW TEMPS TONIGHT THEN WILL 
PROBABLY BE THE COLDEST IN THE WEST AND SOUTH WITH SC PROVIDING SOME 
INSULATION IN THE NORTHEAST.  CURRENT FORECAST IN LINE WITH THIS 
THINKING SO NO BIG CHANGES PLANNED.  BASED ON EXPECTED CLEARING 
SOUTH...WILL GO A CATEGORY UNDER MOS.  WARMUP TO BEGIN LATE IN 
WEEKEND AS WEAK SURFACE RIDGE MOVES THROUGH CWA LATE SATURDAY 
NIGHT/SUNDAY MORNING.  THEN RETURN FLOW SETS UP AHEAD OF SYSTEM 
DEVELOPING OVER SWRN CANADA.  DRY SOUTHWEST FLOW WILL LIMIT CLOUDS 
SO ANITICPATE TEMPS SUNDAY WARMING TO NEAR WARMER MET VALUES. FRONT 
PROGGED TO MOVE THROUGH ON MONDAY AS SURFACE LOW MOVES ALONG THE 
CANADIAN BORDER. ETA/GFS ARE CLOSE AND MOVE THE FRONT TO THE MS 
RIVER BY 18Z MONDAY.  UKMET THOUGH IS A LITTLE SLOWER BY 12Z 
MONDAY.  WILL USE A BLEND OF THE UKMET AND ETA/GFS SOLUTIONS AND 
KEEP FRONT WEST OF RIVER UNTIL 00Z TUESDAY.  MODELS ARE SUGGESTING 
THAT PCPN WITH SYSTEM WILL BE MAINLY POST FRONTAL...WHICH LOOKS 
REASONABLE BASED ON LIMITED MOISTURE RETURN AHEAD OF SYSTEM. WILL 
KEEP MENTION OF SHRA/TSRA IN ALL BUT THE SOUTHEAST SECTIONS UNTIL 
AFTER 00Z TUESDAY. TEMPS MONDAY WILL BE HIGHLY DEPENDENT ON POSITION 
FRONT DURING THE AFTERNOON.  HAVE BACKED OFF SOME IN THE NORTHWEST 
PART OF CWA FROM PREVIOUS FORECAST...BUT HAVE LEFT UPPER 60S/NR 70 
TEMPS ALONE IN THE SOUTHEAST. 

EXTENDED
UPPER TROF MOVING THROUGH REGION TUESDAY/WEDNESDAY WITH AREA ON 
BACKSIDE OF SLOW MOVING COLD FRONT WILL KEEP RAIN CHANCES GOING 
EARLY IN PERIOD.  GFS BRINGS ANOTHER ROUND OF RAIN IN THURSDAY AHEAD 
OF DIGGING SYSTEM OVER SW U.S.  HOWEVER...WILL HOLD OFF ON PCPN FOR 
NOW SINCE MODELS ARE TYPICALLY TO FAST WITH S.W. SYSTEMS.  FRIDAY 
WILL INTRODUCE SHRA/TSRA AS SW SYSTEM LIFTS OUT.  TEMPS WILL STAY AT 
OR JUST ABOVE MEX NUMBERS.

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

$$
DLF