[LeArc] Forecast Discussion : MLI@ 4/24/2003 3:29:01 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 240825
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
325 AM CDT THU APR 24 2003

LATEST RADAR AND SURFACE ANALYSIS SHOWING THE PRECIPITATION MOVING
IN THE AREA...THOUGH AS OF 06Z PRECIPITATION WAS BEING REPORTED ONLY
TO THE SOUTHWEST OF A LINE FROM KAIO TO JUST NORTH OF KIRK.  STILL
LOTS OF SATURATION TO OCCURR...WITH THE EVENING 00Z SOUNDING VERY
DRY...WITH THE WETTEST DEWPOINT DEPRESSION BELOW 700 MB ABOUT 24
DEGREES. SURFACE DEWPOINTS AS LOW AS 18 AT KRFD...THOUGH IT RANGES UP
TO 36 AT KFFL.  HAVE NOTED THAT WHERE IT IS RAINING...DEWPOINTS ARE
IN THE MID 40S AT LEAST.  UPPER LEVEL ANALYSIS INDICATING THAT THE
UPPER LEVEL LOW HAS VERY LITTLE TILT...THOUGH IT HAS A GOOD HEIGHT
RISE/FALL COUPLET AT ALL LEVELS TO MAKE ME THINK THAT IT WILL KEEP
MOVING WELL.  A GOOD SOUTHERLY JET AT 850MB OVER THE TX/OK AREA...AS
HIGH AS 55KTS. A NARROW TOUNGE OF HIGH DEWPOINT AIR FEEDING INTO THE
SYSTEM AT 850 MB...SO NO LACK OF MOISTURE FOR THIS SYSTEM.

MAIN CONCERNS THIS FORECAST INCLUDE PRECIPITATION TODAY THROUGH
FRIDAY AM...AND TEMPERATURES THROUGH THE PERIOD.  ALSO...THE SYSTEM
MOVING IN FOR SUNDAY IS OF SOME CONCERN FOR THUNDERSTORM POTENTIAL.

00Z MODELS APPEAR TO HAVE INITIALIZED REASONABLY WELL...THOUGH GFS
PERHAPS TOO DEEP WITH THE 500MB LOW...BUT ETA AND NGM SEEM ABOUT
RIGHT.  ALSO...THE GFS APPEARS TO BE A LITTLE OVERDONE WITH THE
PRECIP AS OF 06Z...BUT NOT TOO BADLY.  THE MAIN PROBLEM WITH THE GFS
THIS MORNING MAY BE THE BULLSEYES IN THE 700MB OMEGA FIELD TODAY-
PESKY CONVECTIVE FEEDBACK AGAIN.  MODELS ARE IN A LITTLE BETTER
AGREEMENT THAN YESTERDAY...WITH ALL 3 MAIN MODELS RUNNING THE UPPER
LEVEL LOW ACROSS SOUTHERN MISSOURI THURSDAY NIGHT AND FRIDAY
MORNING...AND BY SATURDAY MORNING THE LOW OPENS UP INTO A WAVE...WITH
THE ETA OPENING MORE QUICKLY THAN THE GFS...BUT THE GFS CLOSER TO THE
ETA SOLUTION THAN IT WAS LAST NIGHT.

TODAY THE MAIN QUESTION IS HOW FAR NORTH TO BRING THE LIKELY POPS.
BOTH THE ETA AND AVN ARE KEEPING THE BEST LIFT AND MOISTURE
GENERALLY SOUTH OF HIGHWAY 34...WITH NORTHERN EDGE OF MAIN PRECIP
BAND SOMEWHERE BETWEEN HIGHWAY 30 AND 20.  AFTER SOME COLLABORATION
WITH SURROUNDING OFFICES...HAVE DECIDED TO BRING LIKELY POPS ONLY TO
AROUND HIGHWAY 30...WITH CHANCE POPS NORTH OF THAT...FOR BOTH TODAY
AND TONIGHT.   TEMPS FOR TODAY ALSO TRICKY...WITH PRECIPITATION AND
CLOUDS ACTING TO KEEP IT DOWN...BUT WITH A WARM START RANGING FROM
AROUND 40 TO THE MID 50S.  HAVE DECIDED TO KEEP TO THE TREND OF A
LOW RANGE FROM NORTH TO SOUTH...BUT WITH THE WARMEST TEMPS TO THE
NORTH.

FRIDAY PRECIPITATION MOVES OUT OF THE AREA DURING THE MORNING AND
EARLY AFTERNOON HOURS...A RESULT OF THE UPPER LEVEL LOW EJECTING
MORE QUICKLY THAN ON PREVIOUS FORECASTS.  TEMPS WARM QUICKLY AGAIN...
BUT ARE GOING TO DEPEND ON CLOUDS.  FOR NOW HAVE DECIDED TO KEEP
LOW CLOUDS OUT OF THE AREA...AND HAVE WARMED TO JUST UNDER THE ETA
GUIDANCE VALUES.

VERY LITTLE CHANGE IN THE FORECAST FOR SATURDAY...THOUGH DECREASED
CLOUD COVER A LITTLE TO GET MOSTLY SUNNY WORDING.

NEXT CONCERN IS FOR SUNDAY...WITH A FAIRLY VIGOROUS SHORT WAVE TO
COME THROUGH THE AREA DURING THE DAY.  THERE IS ENOUGH SHEAR WITH
THE WAVE MOVING THROUGH FOR SOME THUNDERSTORM ACTIVITY...WITH THE
LIMITING FACTOR BEING AVAILABILITY OF MOISTURE.  NOT MUCH MODEL
CONSISTENCY HERE...SO CANNOT GET TO EXCITED ABOUT THIS JUST YET...
THOUGH WILL PUT IN A BRIEF MENTION IN HWO THIS MORNING. WARMED TEMPS
A LITTLE DUE TO STRONG SOUTHERLY FLOW...WANTED TO BE A FEW DEGREES
ABOVE GUIDANCE.

MADE NO CHANGES TO LATER PERIODS.  THANKS TO ARX...DMX...LSX AND ILX
FOR COLLABORATION NOTES.

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

$$

LE