[LeArc] Forecast Discussion : MLI@ 5/7/2003 4:12:24 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 072107
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
406 PM CDT WED MAY 7 2003

SURFACE RIDGE SLOWLY BUILDING INTO THE AREA THIS AFTERNOON WITH
DECENT PRESSURE RISES OVER MOST OF EASTERN IOWA AS OF 18Z.  SURFACE
LOW SLOWLY DRAWING OFF TO THE NORTHEAST FROM ITS 18Z POSITION OVER
CENTRAL IL.  ALOFT...850MB LOW OVER EASTERN IA...WITH ASSOCIATED
UPPER LEVEL SHORT WAVE ALMOST STACKED OVER THE TOP OF IT.  HEIGHT
CHANGES INDICATE THAT THE WAVE IS MAINTAINING STRENGTH...AND SHOULD
CONTINUE TO THE NORTHEAST.

MAIN CONCERNS THIS FORECAST INCLUDE CLOUDS AND TEMPS TONIGHT...AND
PRECIPITATION CHANCES AND AMOUNTS FOR THURSDAY THROUGH SATURDAY.

12Z MODELS APPEAR TO HAVE INITIALIZED REASONABLY WELL...THOUGH SOME
PRETTY SIGNIFICANT DIFFERENCES BY 36 HOURS.  THE NGM...AS USUAL...
TOO FAR NORTH IN THE COLD AIR...WITH THE ETA PRODUCING A SLIGHTLY
MORE PROGRESSIVE SOLUTION THAN THE AVN.  CANADIAN...AND UKMET
APPEAR TO FAVOR THE ETA A LITTLE MORE THAN THE AVN...AND HAVE GONE
MAINLY WITH THE ETA THIS AFTERNOON.

TONIGHT LOOKS DRY...WITH THE MODELS AGREEING ON NOT BRINGING THE
WARM FRONT NORTHEAST ACROSS THE CWA UNTIL DURING THE DAY ON
THURSDAY.  THUS...HAVE BACKED OFF PRECIP UNTIL LATE MORNING FOR THE
SOUTHWEST...THEN SPREADING NORTHEAST THROUGH THE DAY.  FOR THE
NORTHERN HALF OF THE CWA BEST CHANCES NOT TIL AFTERNOON.  AN UPPER
LEVEL WAVE COMES ACROSS THE FRONT ON THURSDAY NIGHT...AND WITH THE
PROXIMITY OF THE SURFACE LOW...THUNDERSTORMS QUITE LIKELY.  WITH
THE FRONT IN THE VICINITY...STORMS TO THE NORTH MOST LIKELY TO BE
HAILERS...AND STORMS TO THE SOUTH IN THE WARM AIR MOST LIKELY TO
BE PUTTING OUT NOT ONLY HAIL...BUT STRONG WINDS ALSO.  SHOULD THE
SITUATION SET UP JUST RIGHT...COULD ALSO BE LOOKING AT TRAINING
STORMS NEAR THE FRONT...AND FLOODING PROBLEMS.  FRIDAY WE WILL BE IN
THE WARM SECTOR...SO WE SHOULD GET GOOD AND WARM AHEAD OF THE NEXT
WAVE FOR FRIDAY NIGHT.  ONCE AGAIN...COULD BE LOOKING AT POSSIBLE
SEVERE DEPENDING ON TIMING AND EXACT SITUATION.   LATER SHIFTS CAN
REFINE.

DECAYING MCS FOR THURSDAY...IN WAA WING AHEAD OF NEXT SYSTEM.  MAIN
WAVE THROUGH THURSDAY NIGHT AROUND 06Z.  SECONDARY LOBE THROUGH 12Z
FRI.  NEXT WAVE FRIDAY NIGHT 00-06Z  SATURDAY AFTERNOON/EVENING.

.EXTENDED (SUN-WED)...SUNDAY TO BE CLOUDY AND COOL WITH CHANCE OF
RAIN STILL...WITH THE UPPER LEVEL LOW STILL PASSING OVERHEAD.
EXTENDED RANGE MODELS ARE QUITE DIFFERENT IN THE TIMING OF THE
SURFACE LOW MOVING NORTHEAST OUT OF THE AREA...THOUGH BY SUNDAY
EVENING THE LOW OUGHT TO FAR ENOUGH EAST FOR PRECIP TO BE MOVED OUT.
MONDAY AND TUESDAY REMAIN IN CYCLONIC FLOW ALOFT...THOUGH SURFACE
RIDGING BUILDS IN SO LITTLE/NO PRECIP RISK.  WEDNESDAY WEAK RIDGING
BUILDS IN ALOFT...WITH SOUTHERLY FLOW BEGINNING AHEAD OF NEXT UPPER
LEVEL SYSTEM BY EVENING...SO WILL GO WARMER THAN MONDAY OR TUESDAY.

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

$$

LRE