[LeArc] Forecast Discussion : MLI@ 6/4/2003 2:51:25 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 041949
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
245 PM CDT WED JUN 4 2003

LINGERING VORT LOBE ALOFT...COMBINING WITH TEMPS RISING ABOVE
THE CONVECTIVE LEVELS/UNSTABLE LOWER LAYERS...TO CREATE SCATTERED
SHOWER AND THUNDERSTORM ACTIVITY THIS AFTERNOON. CONVECTION OCCURRING
MAINLY ALONG LATEST MSAS INDICATED SFC CONVERGENT(WEAK) ZONE FROM
NORTH OF ALO...TO CID...AND TO SOUTH OF THE QUAD CITIES. LOW WBZ'S
AND FREEZING LEVELS HAVE ALLOWED ANY SUBSTANTIAL/SUSTAINING SHOWER OR
STORM TO PRODUCE AT LEAST PEA SIZE HAIL. EXPECT WIDELY SCATTERED
ACTIVITY TO CONTINUE ACRS MAINLY THE SOUTHWEST HALF OF THE CWA INTO
THE EARLY EVENING HOURS...BEFORE LOSS OF INSOLATION KILLS IT.

THEN WEAK SFC RIDGE TO OCCUPY THE REGION OVERNIGHT WITH MOSTLY CLEAR
TO PARTLY CLOUDY SKIES. LIGHT WIND REGIME AND LESS CLOUD COVER WILL
ALLOW TEMPS TO REACH LAST NIGHTS PROJECTED LOWS(UPPER 40S-50)...AND
MAY BE A BETTER CHANCE OF PATCHY FOG. STILL NOT SURE ENOUGH OF FOG
THREAT EXISTS TO BE ZONE MENTIONABLE...BUT MAY THROW IT IN LOOKING AT
WHAT HAPPENED IN RIDGE AXIS FURTHER TO THE WEST LAST NIGHT.

STEEP LLVL LAPSE RATES(1000-H85 PROGGED AT UP TO 9.3 C/KM) CONTINUE
ON THU FOR CU FACTORY...BUT WILL BANK ON VORT COMPLEX CURRENTLY
OVERHEAD...TO BE FAR ENOUGH EAST FOR WESTWARD TAILING LOBE NOT TO
KICK OF WIDELY SCATTERED SHOWERS AGAIN. SHORT RANGE MODELS ALL PROG
NEGATIVE OMEGAS AND NVA ON THU THROUGH THE COLUMN AS WELL. BREAKS IN
CLOUD COVER TO ALLOW AT LEAST SOME SUNSHINE(GETTING TOWARD STRONGEST
INSOLATION OF THE YEAR) SHOULD HELP BOOST TEMPS INTO THE LOW TO MID
70S FOR THU HIGHS...EVEN AFTER BIT COOLER START TO THE DAY.

NEXT MAJOR SYSTEM OF CONSEQUENCE..."SNAIL SHELL" VORT SEEN ACRS FAR
SOUTH CENTRAL SASK...IS GENERALLY PROGGED TO ROLL JUST TO THE NORTH
ACRS MN ON FRI. THUS LOOKS LIKE BEST UPPER FORCING AND DYNAMICS TO
REMAIN JUST TO THE NORTH IN LEE OF SYSTEM...BUT ENOUGH SOUTHWARD
TRAILING PUNCH TO SUPPORT ONGOING SHOWER AND THUNDERSTORM CHANCE ON
FRI. THIS SYSTEM TO ACTUALLY DRAWS LEAD VORTS UP OUT OF SOUTHERN
PLAINS TROUGH AND OVER THE LOCAL AREA AFTER 06Z FRI. MODEL TRENDS
OF SLOWING THIS PROCESS...AS WELL AS DELAY IN ADEQUATE SATURATION
WITH INTERVENTION OF OH RVR VALLEY RIDGE AND GULF MOUTH SYSTEM...
SUGGESTS PRECIP THU NIGHT NOT TO GET INTO THE WESTERN CWA TIL AFTER
MIDNIGHT. MAY NOT BE WORTH MENTIONING PRECIP CHANCE ACRS THE EAST
UNTIL FRIDAY. WITH SFC AND UPPER SYSTEMS SPIRALING JUST TO THE
NORTH OF THE AREA...EXPECT SCATTERED SHOWER/STORM ACTIVITY TO LAST
INTO FRI EVENING BEFORE LOSS OF INSOLATION PUTS LID ON CONVECTION
FOR THE NIGHT.

.LONGER RANGE(SAT-WED)...GENERAL PHASING ISSUES STILL THERE IN
MEDIUM RANGE MODELS HANDLING OF OCCASIONAL SYSTEMS DROPPING OUT OF
CANADA AND ACRS THE MIDWEST THROUGH THE EXTENDED PERIOD. WILL MUDDLE
OUT AN ENSEMBLE SOLUTION BETWEEN THE MRF/UKMET/ECMWF. AS FRI SYSTEM
PULLS OUT OF THE AREA...TEMPORARY RIDGING STILL SHOULD MAKE FOR DRY
AND MODERATING SAT. BUT MODELS SUGGEST LINGERING VORT LOBE JUST TO
THE NORTH...OFF EASTWARD PROGRESSING WAVE COMPLEX...MAY COMBINE WITH
INSTABILITY TO CREATE SHOWER POTENTIAL BLEEDING SOUTH INTO THE CWA AS
THE DAY GOES. WILL KEEP SAT DRY FOR NOW AND BUMP UP TEMPS INTO THE
MID UPPER 70S...LOOKING AT PROJECTED THERMAL PROFILES. NEXT IN LINE
VORT/CLOSED UPPER LOW STILL LOOKS ON TARGET TO ROLL OUT OF SOUTH
CENTRAL CANADA AND ACRS THE AREA ON SUNDAY. MRF SLOWEST WITH CLOSED
UPPER FEATURE AND MAY BE THE MORE CORRECT...SUGGESTING SHOWER/
THUNDERSTORM CHANCE HOLDING OFF UNTIL LATE AFTERNOON AND SUNDAY
EVENING. SLOW UPPER SYSTEM STILL TO CREATE WRAP AROUND INSTABILITY
SHOWERS ON MONDAY...AND WITH ASSOCIATED COOL POOL AND CLOUD COVER...
HIGHS MAY HAVE TROUBLE GETTING OUT OF THE 60S. GOOD TEMP MODERATION
STILL LOOKS ON TAP FOR TUE AS STRENGTHENING SOUTHWEST FLOW REALLY
WAA'S AHEAD OF NEXT MAIN NORTHERN PLAINS/ SOUTHERN CANADA SYSTEM.
THIS SYSTEM TO PROGRESS IN NEARLY ZONAL FLOW FOR PRECIP CHANCE IN THE
LOCAL AREA TUE NIGHT INTO WED.


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

$$

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