[LeArc] Forecast Discussion : MLI@ 4/2/2003 4:20:42 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 022208
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
408 PM CST WED APR 2 2003

COMPLICATED WX SITUATION TODAY WITH A STATIONARY FRONT LAYING ACROSS
IA AND NORTHERN IL...FROM A LOW OVER NE NEBRASKA TO NEAR THE
SOUTHERN TIP OF LAKE MICHIGAN.  STRONG SOUTHERLY FLOW HAS PUSHED
TEMPERATURES INTO THE LOW 80S AGAIN FOR THE SOUTHERN HALF OF THE
CWA...BUT A LARGE TEMPERATURE GRADIENT EXISTS FOR THE NORTHERN
THIRD...WITH A CHANGE OF 69 AT KDBQ TO 79 TO KCWI.  UPPER LEVEL
ANALYSIS STILL INDICATING THAT THE 850 AND 700 MB LAYERS ARE STILL
VERY WARM...850 WAS AT 18 DEGREES C...2 DEGREES WARMER THAN
YESTERDAY.  THE END TO THIS QUIET WEATHER IS COMING...AS EVIDENCED
BY THE NICE PRESSURE FALLS OVER CALIF. AND NEV..

MAIN FORECAST CONCERN TODAY HAS BEEN POSSIBILITIES FOR SEVERE WX ON
THURSDAY...AND TEMPERATURES NEXT FEW DAYS.

MODELS APPEAR TO HAVE INITIALIZED REASONABLY WELL. THE ETA APPEARED
TO HAVE THE BEST HANDLE ON THE SURFACE FRONT AT 12 AND 18Z...WITH
THE AVN APPEARING TO BE TOO FAR SOUTH...BUT PRETTY CLOSE.  HAVE
DECIDED TO GO WITH A BLEND OF THE ETA AND AVN MODELS...AS THEY ARE
RELATIVELY CLOSE AND CAN COME UP WITH A REASONABLE SOLUTION WITH
THEIR COMBINATION.

TEMPS THURSDAY THROUGH FRIDAY HAVE A BIG POTENTIAL FOR A BUST...AS
ALL DEPENDS ON THE POSITION OF THE FRONT DURING THAT TIME FRAME...
AND HAVE AS MUCH AS A 10 TO 15 DEGREE DIFFERENCE FROM NORTH TO
SOUTH.  TONIGHT AM FAIRLY COMFORTABLE WITH THE FRONT SINKING TO
ALONG OR PERHAPS JUST SOUTH OF HIGHWAY 2O...AND HAVE GONE JUST A
LITTLE COOLER TONIGHT AT DBQ AS THEY WERE THIS MORNING.  LOCATIONS
SOUTH OF THE FRONT...HAVE STUCK FAIRLY CLOSE TO GUIDANCE AS IT HAS
BEEN DOING WELL ON OVERNIGHT TEMPS.

SEVERE WEATHER REMAINS A POSSIBILITY FOR A RATHER LIMITED AREA ON
THURSDAY LATE AFTERNOON/EVENING.  DEWPOINTS RISE INTO THE UPPER 50S
IN THE WARM SECTOR...AND THERE IS SUFFICIENT LIFT.  CAPES...EVEN IF
YOU TAKE 1/3RD OF THE ETA VALUES...WILL BE CLOSE TO 1000 J/KG...AND
LI VALUES LOOK PRETTY GOOD.  SHEAR ALSO LOOKS VERY GOOD WITH BRN
VALUES IN THE 5 TO 15 RANGE. HOWEVER...MID LEVELS REMAIN VERY WARM
AND AWAY FROM THE FRONTS THINGS COULD BE TOO CAPPED.  NEAR THE EXTRA
LIFT PROVIDED BY THE WARM AND COLD FRONT...THINGS COULD GET VERY
INTERESTING.  TOO SOON STILL TO PIN DOWN EXACT LOCATIONS...BUT THE
BEST BET FOR NOW IS NORTH OF INTERSTATE 80...BUT NO FARTHER NORTH
THAN HIGHWAY 20.   HAVE DECIDED NOT TO PUT SEVERE WORDING BACK INTO
ZONE TEXT TODAY...BUT LATER SHIFTS MAY DECIDE OTHERWISE.

EXTENDED...SUNDAY THROUGH WEDNESDAY
COMPLICATED SYSTEM FOR THIS TIME FRAME...WHICH HAS NOT BEEN HANDLED
WITH ANY CONSISTENCY BY THE EXTENDED RANGE MODELS AT ALL.  YESTERDAY
IT WAS BRINGING IN LOTS OF COLD AIR...BUT NOW LESS COLD AIR IS BRING
BROUGHT IN FROM THE NORTH...THE UPPER LEVEL LOW IS NOT AS DEEP...
AND NEITHER IS THE SURFACE LOW.  AFTER MONDAY NIGHT THE NEW RUN
DEEPENS...AND BEGINS TO LOOK OVERDONE. HAVE WARMED UP TEMPS...AND
REDUCED THE AREAS OF RAIN MIXED WITH SNOW...PUSHING THE RAIN/SNOW
LINE FURTHER NORTH.  SURROUNDING SITES HAVE A SIMILAR RAIN/SNOW
LINE LOCATION.

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

$$

LE