[LeArc] Forecast Discussion : MLI@ 4/15/2003 3:09:15 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 150806
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
306 AM CDT TUE APR 15 2003

SYNOPTIC PICTURE THIS MORNING SHOWS LARGE 500MB RIDGE OVER MIDWEST...
WITH TROF ONSHORE ALONG THE WEST COAST.  AT THE SURFACE...A COLD
FRONT EXTENDS FROM A WESTERN NE LOW INTO SOUTHERN MN AND NORTHERN
WI.  A STRONG PRESSURE GRADIENT CONTINUES...BETWEEN THIS SYSTEM AND
STRONG BERMUDA HIGH.

THE MODELS INITIALIZED MODERATELY WELL AT 00Z...A LITTLE TOO FAR
EAST ON EASTERN CO LOW.  AT 500H AVN IS BEST ON WEST COAST TROF.

THE PRIMARY FORECAST CONCERNS THIS PACKAGE FOCUS ON TWO WEATHER
MAKERS.  THE FIRST SYSTEM WILL MOVE OUT OF THE CENTRAL PLAINS AND
ACROSS THE FORECAST AREA WEDNESDAY AND WEDNESDAY NIGHT...WITH
PRECIP POSSIBLE AS EARLY AS LATE TONIGHT...AND ALSO WITH THE
POTENTIAL FOR SEVERE.  THE SECOND SYSTEM LIFTS OUT OF THE SOUTHERN
PLAINS FRIDAY NIGHT...STALLS OVER THE AREA INTO SUNDAY...AND MOVES
EAST ON MONDAY...PROVIDING AN EXTENDED PERIOD WITH RAIN AND COOL
TEMPS.  BETWEEN THE TWO SYSTEMS SHOULD GET SOME MUCH NEEDED RAIN
ACROSS THE FORECAST AREA.

THE SHORT-RANGE MODELS ARE NOT IN VERY GOOD AGREEMENT WITH THE
FIRST SYSTEM.  THE AVN BRINGS THE BACKDOOR COLD FRONT SOUTH INTO THE
NORTHERN PORTION OF THE FORECAST AREA LATE TONIGHT...THEN SINKING
JUST SOUTH OF THE FORECAST AREA WEDNESDAY AFTERNOON OR EVENING...
WITH THE SURFACE LOW THRU UIN AROUND 06Z WEDNESDAY NIGHT...THEN
KICKING EAST ON THURSDAY.  THE ETA IS SLOWER AND DOESN'T PUSH THE
COLD FRONT MUCH FURTHER SOUTH THAN I-80...WITH THE SURFACE LOW TO
DVN 18Z THURSDAY...A FULL 12 HOURS LATER AND CONSIDERABLY NORTH OF
THE AVN. THE NGM HAS SIMILAR TIMING TO THE ETA AND IS TRENDING
TOWARDS BEING EVEN FURTHER NORTH.  TO COMPLICATE MATTERS THE
EUROPEAN AND UK TAKE THE SOUTHERN AVN SOLUTION.  WILL FAVOR SOUTHERN
SOLUTION DUE TO LAKE EFFECT AND OUTFLOW BOUNDARIES FROM
PRECIPITATION.

LOOKING AT THE SHORT-TERM...THE NOSE OF THE LLJ WILL FOCUS
CONVECTION ALONG THE FRONT AS IT PUSHES SOUTH TOWARDS THE FORECAST
AREA TONIGHT.  STRONG DYNAMICS TONIGHT...ESPECIALLY LATE AND NORTH...
IN THE FORM OF VV'S AND 300MB DIVERGENCE...WILL AID CONVECTION
MOVING SOUTHEAST INTO THE FORECAST AREA LATE TONIGHT AND WEDNESDAY
MORNING...DEGENERATING INTO A GENERAL RAIN ACROSS CENTRAL PORTIONS
BY MID MORNING.  OUTFLOW BOUNDARIES WILL BE A FOCUS FOR
REDEVELOPMENT...ESPECIALLY SOUTH...WEDNESDAY AFTERNOON AND EVENING.
FRONT AND LOW WILL KICK EAST OF THE AREA THURSDAY MORNING.

THE SECOND SYSTEM...AND INVERTED TROF...WILL APPROACH FROM THE
SOUTH FRIDAY NIGHT AND POSSIBLY LINGER THRU SUNDAY...BEFORE GETTING
KICKED EAST MONDAY.  THIS IS LIKELY TO BE A COOL SYSTEM FOR OUR
AREA...AS THE LOW WILL PROBABLY STAY SOUTH...AND COULD PRODUCE
SIGNIFICANT RAINFALL.

WILL STAY CLOSE TO CURRENT FORECAST...WHICH HAS A GOOD HANDLE ON
THESE TWO SYSTEMS.

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

$$

REA