[LeArc] Forecast Discussion : MLI@ 4/11/2003 1:59:08 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 111857
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
150 PM CDT FRI APR 11 2003

.OVERVIEW...REGION REMAINS UNDER SURFACE AND UPPER LEVEL HIGH WITH WEAK
WIND SHIFT LINE JUST NORTH I-80 AT ~18Z.  SATELLITE SUPPORTS NO CLOUDS
WITH SURFACE TEMPS UPPER 60S TO LOWER 70S WITH SUGGESTION OF
COMPRESSIONAL HEATING ALONG WIND SHIFT.  UPPER AIR ANALYSIS SUPPORTS
CANADIAN SHORT WAVE DYNAMICS TO STAY NORTH FOR LITTLE IMPACTS TO AREA
BEYOND SHIFT IN WINDS.

...TEMPERATURES THE FORECAST QUESTION TIL POPS RETURN MID WEEK WITH
NEXT SYSTEM...

.DIAGNOSIS AND DAYS 1-3...WITH FRONT/WIND SHIFT NEAR AREA TONIGHT
WILL TREND HIGH SIDE GUIDANCE BLEND SOUTHERN 2/3 AREA DUE TO MIXING.
THEN FETCH OFF LAKE MARGINAL MARGINAL FOR SIGNIFICANT LAKE EFFECT
EXCEPT FOR NE AND EAST AREAS BUT MID SHIFT SHOULD RE-LOOK AS 20
DEGREE CHANGE TO IMPACT 5 PLUS DEGREES OR MORE ON HIGHS WITH LAKE
TEMPS IN MID TO UPPER 30S.  THUS PLAN NEAR GUIDANCE...EXCEPT 1-2
CATEGORIES BELOW FAR EAST THROUGH LOWS TONIGHT.  SUNDAY...LIGHT EAST
WIND SUPPORTS COOLER SIDE OF TEMPS...GUIDANCE NOW TRENDING THIS WAY
AND SEE NO REASON NOT TO SEE MORE OF THIS NEXT COUPLE OF RUNS. WITH A
LIGHT EAST WIND AND FAIR SKIES...NORMALLY SEE STRONG RADIATIONAL COOLING
EFFECTS.  THEN...WARMUP WITH HIGHS JUST ABOVE BLEND SUNDAY ON A FRESH
SOUTH WIND BY PM AND THEN LOWS IN 50S MONDAY ON MODERATE SOUTH WINDS.
MONDAY HIGHS ARE THE BIG ISSUE...REASONABLE PER ALL MODELS FOR LOW LEVEL
TEMPS OF +14 TO +17C MONDAY PM WITH SW WINDS OF AT LEAST 20 TO 30 MPH.
THIS WITH DOWNSLOPE COMPONENT MAKES LOWER TO MID 80S A CERTAINTY AND
WILL GO THIS HIGH AS MEX IS UNREASONABLE WITH HIGHS JUST MID 70S.  MORE
CONCERNED ABOUT BEING TOO LOW THAN TOO HIGH UNDER MOSTLY SUNNY SKIES.

.EXTENDED (TUE-FRI)...VIGOROUS SHORT WAVE ROTATES OUT OF SOUTHERN PLAINS
LATE TUESDAY INTO WEDNESDAY.  SURFACE LOW TO PASS JUST NORTH OF AREA
WEDNESDAY AM BUT OCCLUDING FOR MARGINAL CHANCE OF SEVERE DUE TO TIMING
ISSUES.  LOTS OF SHOWERS AND STORMS...SO WILL GO LIKELY POPS LATE
TUESDAY AND WEDNESDAY.   MODERATE SPEED OF MOVEMENT AND MODERATE TO
STRONG INTENSITY SUPPORTS PRIMARILY MODERATE RAIN AMOUNTS BUT
INDICATIONS REMAIN OF A PHASING ISSUE QUESTION WITH NORTHERN STREAM...
SIZE OF WAVES SUGGEST THIS MAY TAKE ANOTHER 36-48 HRS TO RESOLVE THIS
MORE PRECISELY. GOOD NEWS...NOW REASONABLE THAT NORTHERN JET PHASING
WON/T SUPPORT A BACKDOOR COLD FRONT WITH/AHEAD OF THIS SYSTEM SO KEEP
TEMPS ON HIGH SIDE THROUGH WEDNESDAY. THEN SOME QUESTION OF WRAPAROUND
SO ADD CHANCE OF RAIN NORTHERN 2/3 EARLY THURSDAY.  THEN TEMPS ON LOW
SIDE OF MEX/FMR WITH CAA AND WRAPAROUND CLOUDS ON INTO FRIDAY WITH
MODERATE TO STRONG SPRING HIGH PRESSURE.


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

$$

NICHOLS