[LeArc] Forecast Discussion : MLI@ 4/23/2003 4:17:30 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 230911
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
411 AM CDT WED APR 23 2003

SURFACE RIDGE HAS SETTLED JUST TO THE EAST OF THE CWA...WITH LIGHT
WINDS OVER THE EASTERN PORTIONS...AND LIGHT SOUTHEAST DEVELOPING
ALREADY OVER THE WEST.  UPPER LEVELS INDICATE A STRONG LOW
DEVELOPING NICELY OVER THE SOUTHERN ROCKIES...WITH DECENT HEIGHT
FALLS OVER A FAIRLY LARGE AREA.  LOW LEVEL SURFACE FLOW BRINING
MOISTURE UP FROM THE GULF...AND THIS SYSTEM SHOULD BE WELL SUPPLIED
WITH MOISTURE.

MAIN FORECAST CONCERNS THIS PERIOD INCLUDE TEMPERATURES TODAY AND
THE ONSET OF PRECIPITATION LATE TONIGHT...CONTINUING INTO EARLY
FRIDAY.

00Z MODELS APPEAR TO HAVE INITIALIZED REASONABLY WELL...THOUGH THE
GFS SEEMS A LITTLE TOO DEEP WITH THE LOW OVER NM...AND THE ETA NOT
DEEP ENOUGH.  MODELS ARE NOT QUITE IN AS GOOD AGREEMENT AS THEY
WERE YESTERDAY...WITH THE GFS A LITTLE DEEPER AND FARTHER SOUTH THAN
THE ETA BY 60 HRS...AND BY 84 HRS THE GFS STILL HAS A CLOSED LOW
OVER TN...WITH THE ETA HAVING OPENED UP AND IS A LITTLE FARTHER EAST
WITH THE RESULTING WAVE.  GFS SEEMS TO BE THE MOST CONSISTENT WITH
ITS HANDLING OF THIS SYSTEM...WITH THE ETA TRENDING THE SURFACE
FEATURES FURTHER SOUTH TOWARDS THE GFS SOLUTION...ESP. AROUND 60
HRS.  THAT SAID...THE GFS ALSO APPEARS TO BE HAVING SOME CONVECTIVE
FEEDBACK PROBLEM AROUND 18Z TODAY...WITH A BULLSEYE OF PRECIP OVER
THE KS/OK BORDER.  HAVE DECIDED TO GO WITH A BLEND OF THE
SOLUTIONS FOR NOW...THOUGH FAVORING A MORE SOUTHERLY AND SLIGHTLY
WETTER VERSION OF THE ETA.

TEMPS TODAY A LITTLE TRICKIER THAN THEY WERE YESTERDAY.  CIRRUS TO
BEGIN INCREASING AFTER MIDDAY...SOUTHEAST FLOW...AND TEMPS STARTING
ABOUT THE SAME VALUES AS YESTERDAY MORNING...ARE ALL FACTORS THAT
TEND TO KEEP TEMPS FROM RISING TOO FAR.  HOWEVER...FULL SUN...WAA
ALOFT...AND INCREASING MIXING SHOULD HELP TO WARM TEMPS OVER
YESTERDAY. ACTUALLY...GIVEN THAT TEMPS ARE WARMER OVER THE WESTERN
PORTIONS OF THE CWA THAN THEY WERE YESTERDAY...AND WARMER MID LAYERS
TO THE WEST WILL CAUSE THE MAX TEMPERATURE GRADIENT ACROSS CWA TO BE
FROM WEST TO EAST RATHER THAT FROM SOUTH TO NORTH TODAY.  ETA
PROBABLY TOO WARM...ESPECIALLY TOWARDS THE NORTH OF THE CWA.

FAVORING THE WAY ETA BRINGS IN PRECIPITATION TONIGHT...PUTTING IN A
CHANCE OF RAIN FOR THE SOUTHWESTERN THIRD OF THE CWA AFTER MIDNIGHT.
PULLED THE PRECIPITATION A LITTLE FARTHER SOUTH THAN IN THE GOING
FORECAST...TO ACCOUNT FOR THE LOWER DEWPOINTS THAT SEEM TO GET PULLED
OVER THE NORTHEASTERN THIRD OF THE CWA IN THE SOUTHEAST SURFACE
FLOW.  THURSDAY...IT IS YET TO BE RESOLVED AS TO WHERE THE BANDS OF
RAIN SET UP...DUE TO MODEL DIFFERENCES...BUT HIGHEST POPS ARE
TOWARDS THE SOUTH...AND ALL IN LIKELY CATEGORY.  FRIDAY
PRECIPITATION MAY BE KIND OF SLOW TO LEAVE CWA...AND HAVE KEPT
LINGERING PRECIPITATION ACROSS SOUTH ALL DAY.  BY FRIDAY NIGHT ALL
PRECIP IS OFF TO THE EAST...BUT CLOUDS OUGHT TO LINGER...AND HAVE
WARMED TEMPS A LITTLE TO MATCH.

NO PRECIPITATION FOR SATURDAY...AND RIDGE BUILDING IN WITH NORTHERLY
FLOW.  IT OUGHT TO BE KIND OF COOL...BUT OTHERWISE A NICE DAY.  NO
CHANGES MADE TO SATURDAY OR ANY LATER PERIODS.

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

$$

LE