[LeArc] Forecast Discussion : MLI@ 5/22/02 2:51:09 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 220751
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
250 AM WED MAY 22 2002

IMPRESSIVE SPRING STORM ROTATTING NORTHEAST OVER THE NORTHERN ROCKIES
THIS MORNING.  170M HEIGHT FALLS AT H300 WITH SYSTEM OVER WESTERN WY
TUESDAY EVENING.  STRONG SURFACE PRESSURE GRADIENT DEVELOPED OVER PLAINS
IN RESPONSE TO THE SYSTEM WITH SEVERAL LOCATIONS IN NE/KS/SD REPORTING
SUSTAINED WINDS AROUND 30KTS AT 06Z.  PREVIOUS SHIFT NOTED THAT ETA
INITIALIZED A LITTLE WEAK WITH RESPECT H5 HEIGHTS OVER NORTHERN ROCKIES
WHILE THE AVN WAS CLOSER TO THE 00Z ANALYSIS.  MODELS ARE SIMILAR WITH
HANDLING THE SYSTEM THROUGH 24HRS THEN ETA SPEEDS THE SURFACE FRONT UP
WHILE THE AVN FAVORS A SLOWER MOVEMENT.  AVN SOLUTION SEEMS REASONABLE
WITH THE STRONG HIGH PRESSURE STILL IN PLACE OVER THE SERN U.S. AND THE
UPPER FLOW OVER CENTRAL U.S. BECOMING MORE SWLY IN RESPONSE TO WAVE
MOVING THROUGH ROCKIES.

WIND/TEMPS/CLOUDS ARE THE SHORT TERM ISSUES.  STRONG WINDS ONGOING
OVER PLAINS RATHER OMINOUS AT 06Z. TALKED OVER ADVISORY PLANS WITH ARX
AND DMX AND FEELING HERE IS TO HOLD OFF ON HEADLINE BASED ON AMOUNT OF
VEERING IN THE LOWER LEVELS. BY 18Z WINDS STILL VEER FROM SSE AT SFC
TO SW AT 850.  WILL TAKE WINDS TO JUST UNDER ADVISORY CRITERIA THIS
AFTERNOON MAINLY WEST OF THE MISSISSIPPI.  PRESSURE GRADIENT AND CLOUD
COVER TONIGHT WILL KEEP STRONG WINDS GOING INTO THE OVERNIGHT HOURS.
MOS CLOUD FORECAST SHOWS LOWER CEILINGS  BY THIS AFTERNOON. THIS LOOKS
TOO AGGRESSIVE BASED ON RH PROGS AND WILL PLAN ON ONLY SOME CI DURING
THE DAY WITH CLOUDS THICKENING OVERNIGHT.  WITH STRONG SFC WINDS AND
THIN CI ONE WOULD THINK THAT TEMPS WOULD TAKE OFF TODAY.  HOWEVER...
MODEL SOUNDINGS ONLY MIX OUT TO JUST OVER 900MB BY THIS AFTERNOON AND
PER DMX COORDINATION SSE FLOW IS NOT FAVORABLE FOR A BIG WARM UP.
CURRENT FORECAST REFLECTS THIS THINKING...SO WILL HOLD TEMPS TODAY IN
THE 70 TO 75 RANGE.  MODELS CONTINUE TO SUGGEST  SOME THETA-E
ADVECTION AND MOISTURE CONVERGENCE WITH MODERATELY STEEP MID LEVEL
LAPSE RATES LATE WEDNESDAY NIGHT...SO WILL CONTINUE CHANCE POPS.
MODELS MOVE COLD FRONT THROUGH THURSDAY AFTERNOON AND EVENING.  TIMING
IS RIGHT FOR SEVERE THREAT...HOWEVER INSTABILITY WILL BE MARGINAL.
MODELS ARE MOVE AGRESSIVE WITH THIS RUN IN MOVING FRONT FURTHER S INTO
MO FRIDAY.  BASED ON THIS WILL BACK OFF POPS DURING THE DAY.  AVN PROGS
SUGGESTING EARLY PART OF MEMORIAL DAY WEEKEND WILL BE A WASHOUT AS IT
MOVES SURFACE WAVE ALONG BOUNDARY OVER NORHTERN MO/CENTRAL IL.  TEMP
FORECAST AFTER TODAY WILL NOT VARY MUCH FROM MOS NUMBERS.  EXCEPTION
WILL BE FRIDAY WITH EASTERLY FLOW SETTING UP OFF LAKE MICHIGAN. WILL
GO A FEW DEGREES UNDER MAV ESPECIALLY IN THE EAST.

THANKS TO ARX AND DMX FOR THE EARLY COORDINATION.

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

DLF