[LeArc] Forecast Discussion : MLI@ 9/7/02 2:41:32 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 071946
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
240 PM CDT SAT SEP 7 2002

UNSEASONABLY WARM PATTERN TO LAST A FEW MORE DAYS...AS DVN CWA
CONTINUES TO LIE IN WESTERN CLUTCH OF LARGE EASTERN CONUS SFC
ANTICYCLONE. GOING WITH PERSISTENCE...EXTENT OF HIGH AND LOW TEMPS
OVER NEXT TWO DAYS...AS WELL AS OVERNIGHT FOG POTENTIAL WILL REMAIN
MAIN NEAR TERM FORECAST QUESTIONS.

LARGE UPPER RIDGE OVER MUCH OF CONUS TO HOLD FIRM THROUGH MON...BUT
DOES GET BEAT DOWN SOME BY THEN AS IT EATS WEST COAST L/W TROUGH AS
IT STRIDES INLAND. SOUTHEAST SFC TRAJECTORIES AROUND RIDGE AXIS HAVE
HELD REAL SFC JUICE OFF TO THE WEST...AND ACTUALLY HAS PINCHED OFF
SFC MOISTURE TONGUE THROUGH NORTHERN KS AND MO. LARGE 65 TO 70 DPT
FIELD HAS POOLED ACRS NORTHWEST IA AND ACRS THE EAST DAKOTAS...MN AND
WI. FEEL THIS SET UP WILL MAKE FOR ANOTHER NIGHT OF TEMPS FALLING TO
COOLER READINGS THAN EXPECTED...PLUS NO REAL FOG TO THE EXTENT OF
ZONE MENTIONABLE. ACTUALLY FWC LOWS LOOK DECENT FOR TONIGHT AND WILL
FOLLOW. LLVL SOUTHERLY FETCH WILL HELP DPTS REACH MID TO UPPER 60S ON
SUNDAY...AND THIS HIGHER AMBIENT MOISTURE SHOULD KEEP HIGHS FROM
SURPASSING TODAYS VALUES. ALSO...FEEL NGM ONTO SOMETHING WITH SLIGHT
CAA IN THE H9-H85 LAYER ON SUNDAY...AS CONTINUING SOUTHEAST FLOW IN
THAT LAYER TAPS INTO COOLER THERMAL POOL FROM BOWELS OF LLVL RIDGE
OVER NORTHERN GULF STATES. SPURIOUS AVN PRECIP UNDER RIDGE SUNDAY
AFTERNOON(AND MONDAY)WILL BE IGNORED.

HIGHER DPTS AND SOME SLIGHT CONVERGENCE MAY LEAD TO BETTER FOG
POTENTIAL SUNDAY NIGHT...ALTHOUGH SOUTHERLY SFC BREEZE MAY LAST
ENOUGH INTO THE NIGHT TO HAMPER SFC CLOUD PRODUCTION. NOT CONVINCED
ENOUGH EITHER WAY AT THIS POINT TO REMOVE ONGOING MENTION. BETTER
FETCH OF LLVL/H85 RH'S AROUND RIDGE AT THAT LEVEL ON MONDAY MAY LEAD
TO ENOUGH CU PRODUCTION TO WARRANT PARTLY CLOUDY WORDING....AND
ANOTHER VERY WARM AND HUMID DAY ON TAP. WARMER MAV HIGHS LOOK MORE ON
TARGET FOR MON...BUT STILL MAY BE TOO LOW. SHORT RANGE MODELS DIFFER
ON MONDAY NIGHT FROPA TIMING WITH AVN SLOWEST...BUT ALL SUGGEST POST-
FRONTAL PRECIP RIBBON. THIS WOULD SUGGEST CHANCE DELEGATED TO LATE
WORDING...BUT STILL AM WARY OF ANY PRE-FRONTAL POTENTIAL AT THIS TIME
AND WON'T CONFINE POPS TO PAST THE BEWITCHING HOUR JUST YET.

.LONGER RANGE (TUE-SAT)...AFTER FROPA EVENT LATE MONDAY NIGHT/TUE
MORNING...QUESTIONS ON EXTENT OF MID WEEK COOL DOWN REMAIN. EXPECT
LINGERING POST-FRONTAL PRECIP AND CLOUD DEBRIS TO LAST AT LEAST INTO
THE MID TUESDAY PERIOD...WITH ADDITIONAL VORT ENERGY TRAINING OVER
AREA IN WEST-NORTHWEST FLOW. THIS INHERENT CLOUD COVER AND CAA DAY
SUPPORT ONGOING AND COOLER THAN GUIDANCE HIGHS FOR TUE. INCOMING HIGH
FOLLOWING FROPA HAS MOST OF ITS MOMENTUM IN THE LOWER LEVELS...WILL
SWEEP ACRS IA ON WED...AND EVENTUALLY SPILL DOWN ACRS THE OH RVR
VALLEY BY THU. MRF GUIDANCE HIGHS HAVE TRENDED COOLER WITH LATEST
RUN...BUT ONGOING PACKAGE STILL ADVERTISING TEMPERATURES WELL BELOW
THESE VALUES. WITH HIGH LOOKING TO BE MORE IN THE WAY OF PACIFIC
ORIGIN AND LATEST PROGGED LLVL THICKNESSES AND THERMAL PARAMETERS
SUGGEST POSTED HIGHS/LOWS A BIT OVERDONE ON COOL SIDE...MAY TREND MID
WEEK TEMPS UP. STILL...THIS TIME OF YEAR WHEN HIGHS HAVE ALL THEIR
REAL PUNCH IN THE LOW LEVELS...MODELS STILL MAY BE UNDER-DOING ITS
COOLING POTENTIAL AND REAL STRENGTH. AND WITH AT LEAST THE MRF
TRENDING COOLER FOR THIS TIME PERIOD...WON'T MAKE BIG JUMP UP FOR
NOW...AND AWAIT LATER RUNS TO SEE HOW THEY HANDLE HIGH AND EXTENT OF
CAA. MEDIUM RANGE MODELS STILL VARY SOMEWHAT ON PHASING WITH NEXT
UPSTREAM WAVE BY LATE WEEK...AHEAD OF REINFORCING HIGH AND COOL SHOT
FOR NEXT WEEKEND. SEEMS LATEST MEDIUM RANGE MODEL ENSEMBLE OF WAVE
PHASING WITH FAY'S REMNANTS...TO SHUNT MAJOR PRECIP EVENT TO SOUTH OF
LOCAL AREA OF CONCERN...OVER THE LOWER TO MID MS RVR VALLEY REGION
NEXT FRI. STILL WILL KEEP SHOWER CHANCE FOR FRI AS SOME OF THE
NORTHWARD ADVECTIVE/PHASING PROCESSES COULD STILL BRING PRECIP UP
THIS FAR NORTH...AND TREND SAT AS A DRY AND MODERATING DAY AHEAD OF
NEXT COLD PUSH.


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

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