[LeArc] Forecast Discussion : MLI@ 10/16/02 3:05:53 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 162010
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
305 PM CDT WED OCT 16 2002

INITIAL VORT/CVA SURGE...SEEN ON W/V IMAGERY PUNCHING SOUTHEAST ACRS
NORTHEAST KS ATTM...WILL CONTINUE TO PUSH ACRS MO TONIGHT. SOME SFC
REFLECTION IN FORM OF TROUGH AND WEAK WAVE EVIDENT ON LATEST MSAS AND
SFC ANALYSIS ACRS EAST SD...NE AND WEST KS...BUT EXPECT THIS TO WASH
OUT OVER NIGHT AS IT BUILDS EAST INTO THE RIDGE. STILL EXPECT LEAD MO
VORT TO INDUCE OVER-RUNNING/ISENTROPIC PRECIP THREAT ON ITS NORTHERN
EDGE ACRS THE SOUTHERN CWA TONIGHT...REACHING WESTERN IL AFTER
MIDNIGHT. FCST SOUNDINGS AND PROGGED BOUNDARY LAYER THERMAL
PARAMETERS SUGGEST PRECIP TO REMAIN LIQUID FORM ACRS SOUTH OVERNIGHT
AND INTO THU MORNING...ALTHOUGH INITIALLY DRY LLVLS MAY EVAPORATIVE
COOL ENOUGH FOR SOME MIX EARLY THURSDAY MORNING. EXITING VORT TO THE
SOUTHEAST AND THUS SHUT OFF OF POS OMEGA FIELDS WOULD END PRECIP ACRS
THE SOUTH BY LATE MORNING. SECOND PUNCH IN FORM OF ELONGATED AND
DIGGING WAVE TRAIN TO STAB SOUTH ACRS IA IN DEEPENING TROUGH LATER
TONIGHT AND THROUGH MIDDAY THUR. MODELS STILL DEVELOP SFC LOW
REFLECTION AHEAD OF THIS ACRS MN AND DROP IT TOWARD NORTHERN IL ON
THU...FEATURE NOW PROGGED TO BE MUCH WEAKER AND AN OPEN WAVE. BOTH
CONCEPTUAL MODEL FORCING AND PROGGED POS OMEGA/LLVL CONVERGENT FIELDS
WOULD BRING PRECIP AHEAD OF THIS WAVE ACRS MAINLY NORTH HALF OF THE
CWA THU AND TAPER OFF BY BY MID AFTERNOON. AS FOR START TIME...EXPECT
DRY AIRMASS IN PLACE AND LATER BOUT OF SATURATING ISENTROPIC LIFT
AHEAD OF SECONDARY(AND MAIN) VORT COMPLEX TO DELAY PRECIP REACHING
SURFACE ACRS THE NORTHWEST HALF OF THE CWA NOT TIL AFTER MIDNIGHT...
AND NOT CROSS THE MISSISSIPPI UNTIL AROUND 12Z THU. MODELS HAVE
TRENDED TO A LOWER QPF...WHICH MAKES SENSE WITH SUCH LIMITED MOISTURE
TO WORK WITH AND SHOULD BE A LIGHT PRECIP EVENT. WITH EXPECTED QUICK
TEMP DROP OFF IN BOUNDARY LAYER AFTER SUNSET ACRS NORTH(ALTHOUGH
MID/HIGH CLOUDS WILL BE THICKENING FROM WEST)...INITIAL PRECIP SHOULD
BE PRIMARILY LIGHT SNOW...WITH SOME MORNING MIX STILL POSSIBLE ALONG
THE I-80 CORRIDOR. AS DAY PROGRESS AND BOUNDARY LAYER THERMALLY
RECOVERS...EXPECT SWITCH BACK OVER TO MIX OR PRIMARILY RAIN BY
MIDDAY. SOME LIGHT SNOW ACCUMULATION ACRS THE NORTHERN THIRD STILL
POSSIBLE ON GRASSY AND ELEVATED SFCS...BUT MAY NOT BE MUCH MORE THAN
A SLOPPY DUSTING WITH INITIAL MELTING/SFC IMPACT AND GENERAL LIGHT
PRECIP SCENARIO TO BEGIN WITH. TEMPS MAY NOT MAKE IT OUT OF THE 30S
ACRS THE NORTH...WITH LOW 40S ACRS THE SOUTH.

STILL EXPECT BRIEF BUT STRONG BOUT OF PREFRONTAL WAA ON FRI TO
POSSIBLY PUMP TEMPS TO AROUND 60 OR HIGHER BY LATE AFTERNOON. IF
FRONTAL FEATURE PROGRESSION SLOWS AND SUNSHINE PREVAILS...WOULDN'T BE
SURPRISED FOR MID 60S ACRS WESTERN IL BY LATE FRI AFTERNOON. WILL
STILL BANK ON DRY FROPA FRI NIGHT AS NEXT VIGOROUS WAVE DROPS ACRS
WI.

.LONGER RANGE(SAT-WED)...WILL CONTINUE TO LEAN TOWARD GENERAL
UKMET/ECMWF ENSEMBLE AGAIN THROUGH EXTENDED PERIOD...LOOKING AT THEIR
CONTINUING CONSISTENCY WITH LATEST RUNS. START OF EXTENDED PERIOD
LOOKS LIKE A DRY AND COOLING DAY BEHIND FROPA...AS INCOMING SFC RIDGE
BRINGS ANOTHER REINFORCING SHOT FROM CENTRAL CANADA. MAYBE ENOUGH
DELAY IN REAL CAA FOR SATURDAY HIGHS TO REACH UPPER 50S WITH SOME
INSOLATION AND MIXING. HIGH CONTINUES TO SETTLE ACRS AREA FOR FAIR
AND SEASONABLY COOL SUNDAY...PROBABLY PRETTY SIMILAR TO SAT. WILL
PLAY MONDAY AS MODERATING DAY ON BACKSIDE OF RIDGE WITH HIGHS PUSHING
60...AND PROBABLY TIME FOR DISTURBANCE TO DROP DOWN IN BROADENING
CYCLONIC FLOW OVER AREA FRO PRECIP THREAT ON TUE. MRF AND LATEST
UKMET TIMING WITH DISTURBANCE OVER AREA ALSO SUPPORT TUE AS WORTHY OF
PRECIP MENTION...ALTHOUGH SFC RIDGE OVER WEST GULF TO LIMIT MOISTURE
AVAILABILITY AGAIN. WILL GO WITH ALL RAIN FOR NOW..BUT IF PRECIP
LINGERS INTO THE NIGHT OR IS DELAYED...MAY BE SOME SNOW/MIX POTENTIAL
ACRS THE NORTH LATER TUE NIGHT. ANOTHER ROUND OF COOLING HIGH
PRESSURE FOR NEXT WED BEHIND TUE SYSTEM.

COORDINATED WITH ILX...THANX!


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

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