[LeArc] Forecast Discussion : MLI@ 3/31/2003 2:07:00 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 312004
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
200 PM CST MON MAR 31 2003

.OVERVIEW...ANALYSIS SHOWS WARM FRONT APPROACHING WITH AREA OF LIGHT
RAIN AND SPRINKLES SLIDING SOUTHEAST FROM SOUTH CENTRAL MINNESOTA.
DISTANCE TIME FEATURE SUGGEST BACKSIDE TO SLIDE EAST BETWEEN 00 AND
04Z. SOME SUGGESTION OF SHOWERS POSSIBLE WITH ACTUAL WARM FRONT THIS
EVENING.  UPPER AIR SHOWS DRY SW WINDS SETTING UP FOR MUCH WARMER
WEATHER WITH LITTLE MOISTURE AS 850 TEMPS PUSH 12-15C AFTER FRONTAL
PASSAGE.  NEXT SYSTEM NEARING PACIFIC COAST BUT DIVING SOUTH SO WILL
TAKE TIME TO REACH AREA.  LOTS OF COLD AIR STILL IN CANADA WITH COLD
CANADIAN HIGH BUILDING IN YUKON TERRITORIES.

...EVENING POPS TONIGHT...THEN WARMUP NEXT FEW DAYS WITH SEVERE
POTENTIAL THURSDAY INTO EARLY FRIDAY FORECAST ISSUES...

DIAGNOSIS AND DAYS 1-3...ONCE AGAIN...ETA TOO DRY WITH BEST SOLUTION
TAKING HALFWAY BETWEEN GFS-AVN AND ETA...OR SLIGHTLY WETTER THAN NGM.
USE NOWCAST TOOLS FOR POPS TONIGHT WHICH SUPPORT CHANCE POPS AT LEAST
NE 1/3 AREA...THEN CLEARING  AND MILDER.  MODERATE SOUTHWEST WIND AND
LOTS OF SUNSHINE SUPPORTS VERY WARM TEMPS WITH HIGHS ABOVE GUIDANCE
WITH NON-HYDROSTATIC COMPRESSION TUE/WED.  PLAN FOR HIGHS NEAR 80
INTO LOWER 80S WEST CENTRAL CWFA JUST AHEAD OF STATIONERY FRONT.
WHOA...OUR CLIMATOLOGICAL BACKDOOR COLD FRONT WILL BE A BEAR NEXT FEW
DAYS AS LATEST MODEL MIX IS INDEED...AS NORMAL...50+ NM FURTHER
SOUTH.  PREFER UKMET/ETA SUGGESTING IT TO SAG TO ITS NORMAL I-80 AXIS
BY WEDNESDAY FOR 25+ DEGREE DIFFERENCE...EXPECT MORE SOUTHWARD SAG
TO REAR ITSELF NEXT 12-24 HOURS...JUST HAVE TO GUESS FOR NOW.  THIS
AND MORE COHERENT SHORT WAVE THURSDAY WITH 988 TO 995 MB SFC LOW
SUPPORTS LATE PM/EVENING SUPERCELLS ALONG/JUST SOUTH OF LOW TRACK
BETWEEN 21Z AND 06Z FRIDAY. SEVERE THREAT ALREADY IN HWO AND NO NEED
TO CHANGE FOR NOW.  BEST ANALYSIS SUGGESTS SFC DEWPOINTS TO REACH
~55-60F AHEAD OF COLD FRONT LATE THURSDAY.  PLAN TO DO FIRST BLEP
CALCULATIONS TOMORROW...BUT 0-1KM HEAR AND SFC-850 THETA-E PROFILES
PER ETAX/UKMET AND VERY ROUGH BLEP CALCULATIONS SUGGEST 60+ MPH STRAIGHT
LINE WINDS WITH SOME HAIL AND RISK OF ISOLATED TORNADOES (AT LEAST F0 TO
F1 INTENSITY) IF HIT 82+F WITH 53+ DEWPOINTS AND WE GET CONVECTIVE
INITIATION.  THESE THERMODYNAMIC VALUES APPEAR QUITE PLAUSIBLE LATE
THURSDAY. BEST GUESS IS HIGHS ALONG HIGHWAY 20 CORRIDOR THURSDAY AND
POSSIBLY AS EARLY AS WEDNESDAY TO STRUGGLE TO REACH 60 DEGREES...WHILE
LOW 80S (OR EVEN HIGHER WITH COMPRESSION) THE RULE SOUTH/NEAR/ALONG OF
I-80. AHHH...JUST LOVE SPRING.

.EXTENDED (FRI-MON)...CANADIAN HIGH SLIDES IN FRIDAY WITH SOME
OVERRUNNING TO DEVELOP LATE SATURDAY INTO SUNDAY WITH LARGE
UNCERTAINTY ON TRACK OF LOW.  APPEARS MODERATE RAINS IN STORE WITH
LOCALLY HEAVY POTENTIAL.  WILL KEEP CHANCE POPS FOR NOW DUE TO TIMING
ISSUES AND TRACK FOR ANOTHER 24 HOURS.

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

$$

NICHOLS