[LeArc] Forecast Discussion : MLI@ 3/30/2003 1:50:18 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 301948
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
145 PM CST SUN MAR 30 2003

.OVERVIEW...ANALYSIS SHOWS COLD AIR OVER REGION WITH LOTS OF OPEN
CUMULUS DEVELOPING PAST 2-3 HOURS ACROSS CWFA DUE TO LATE MARCH
SUNSHINE. RADAR SUPPORTS VISUAL REFERENCE OF VIRGA IN FORM OF SPRINKLES
AND FLURRIES WITH LOW WBZ (WET BULB ZERO) RUNNING 500-1,000' AGL.
NOWCAST TOOLS SUGGEST THIS TO CONTINUE WITH SOME LIGHT RAIN AND SNOW
SHOWERS ALSO POSSIBLE THROUGH 22-23Z WITH MORE HEATING. UPSTREAM ENERGY
INDICATES WEAK WARM FRONT TO PASS TOMORROW WITH INDICATIONS OF SOME
CLOUDS AND POSSIBLY LIGHT RAIN OR EVEN SOME WET SNOW FAR NORTH WITH
PASSAGE BEFORE MUCH WARMER CONDITIONS MOVE IN.

...LOWS TONIGHT AND THEN CLOUDS AND POPS AND IMPACTS ON TEMPS MONDAY
THEN WARMUP AND POPS AND SEVERE POTENTIAL THURSDAY WITH NEXT SYSTEM...

DIAGNOSIS AND DAYS 1-3...DIABATICALLY DRIVEN OPEN CUMULUS OF LIGHT
SHOWERS AND FLURRIES ONLY SUGGESTED BY ETA WITH AVN MORE REASONABLE.
ALL INDICATIONS TONIGHT TO BECOME MOSTLY CLEAR WITH LIGHT WINDS FOR
NEAR IDEAL RADIATIONAL COOLING...OR LOWS NEAR TO JUST BELOW GUIDANCE.
MID CLOUDS TO ARRIVE EARLY MONDAY NW 1/3 NEAR SUNRISE AND SLIDE OVER
MOST AREA. WITH STRENGTH OF BAROCLINICITY AND LOW LEVEL FORCING
SUGGESTED BY ALL MODELS...WILL LEAN SLIGHTLY MORE MOIST THAN ETA.
THUS...SPRINKLES SW EARLY AND ALSO S SECTIONS AND SLIGHT CHANCE RAIN
MONDAY CENTRAL AND 40/50 POPS ALONG HIGHWAY 30. FAR NE WILL GO WITH
LIKELY POPS OF RAIN WITH SOME WET SNOW POSSIBLE NEAR FREEPORT AND
DUBUQUE. TEMPS WILL BE A CHALLENGE WITH MID 60S FAR SW AND UPPER 40S (IF
THAT) FOR NE. CLOUDS AND POPS WILL BE THE KEY SO PASS THIS TO LATER
SHIFTS.  MILD SW WINDS ARRIVE MONDAY NIGHT THROUGH WEDNESDAY WITH TEMPS
NEAR TO ABOVE (ESPECIALLY ABOVE DURING DAY) GUIDANCE WITH SW TO SSW
WINDS...EXPECT HIGHS TO TOUCH OR REACH LOWER 80S SW AREAS TUE/WED.

.EXTENDED (THU-SUN)...COMPLEX SITUATION...ALL MODELS INDICATE BACKDOOR
COLD FRONT LATE WEDNESDAY JUST NORTH OF AREA.  SUSPECT SYSTEM TO SAG A
TAD MORE SOUTH THAN ALL MODELS NOW SUGGEST WHICH IS CLIMATOLOGICALLY
MORE REASONABLE ALONG WITH UPPER SPLIT FLOW DUE TO COLD AIR OVER GREAT
LAKES (32-36F).   KEY IS...WILL IT BE ~25NM OR POSSIBLY AS MUCH AS 100+
MILES FURTHER SOUTH.  NEVERTHELESS EITHER WAY...A DEEP LOW PRESSURE
SYSTEM IN FAST WSW FLOW WILL PASS OVER OR JUST NORTH CAUSING FAVORABLE
CONDITIONS FOR SOME CONVECTION THURSDAY WITH OPEN GULF. PREFER ONCE
AGAIN MORE STABLE UKMET AND EVEN ECMWF AS GFS-AVN APPEARS TOO FRAGMENTED
ON ENERGY. WILL UPDATE HWO AS NEXT 24-36 HOURS WILL BECOME EVIDENT OF
RISK POTENTIAL. GENERAL PATTERN IS CONDUCIVE FOR SUPERCELLS AND IF THIS
OCCURS...MAY BE SIGNIFICANT. ENOUGH SAID ON THIS...ALSO INTERESTING LATE
SATURDAY/SUNDAY PER UKMET/ECMWF SOLUTIONS WITH EVEN GFS-AVN ALSO
SUGGESTING MORE ENERGY. UKMET MOST OMINOUS FOR RAIN AND YES SOME SNOW BY
SUNDAY AND GFS-AVN MORE CHANCE CATEGORY POPS WHICH WILL HOLD WITH FOR
NOW.  WITH COLD AIR UPSTREAM ON ANALYSIS...VIEW IS ECMWF AND POSSIBLY
UKMET THE MORE REASONABLE SOLUTION THIS WEEKEND.  THE SIZE OF BOTH
SYSTEMS NEXT 6+ DAYS SUGGEST HAVING DECENT IDEA ON EXTENT/POTENTIAL OF
SEVERE THURSDAY AND WET/WINTRY STUFF THIS WEEKEND NEXT 24 HOURS OF SO.

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

$$

NICHOLS

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