[LeArc] Forecast Discussion : MLI@ 10/25/02 2:23:11 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 251931
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
230 PM CDT FRI OCT 25 2002

.OVERVIEW...SOUTHWEST FLOW CONTINUES ACROSS UNITED STATES WITH WEAK
EMBEDDED DISTURBANCES.  SURFACE ANALYSIS SHOWS HIGH NE OF GREAT LAKES
WITH WEAK SURFACE LOW IN OHIO VALLEY WITH LOBE OF HIGH PRESSURE BACK
INTO CENTRAL PLAINS.  LOTS OF LOW CLOUDS ACROSS EASTERN 2/3 OF UNITED
STATES.  SOME LINGERING LIGHT RAIN NOW MOVING EAST OUT OF OUR AREA AS
SURFACE LOW HEADS EAST.  UPPER AIR SHOWS WEAK RIDGING WITH ONLY MINOR
CHANGES IN LARGE SCALE FLOW WITH JET FROM NEW ENGLAND INTO SOUTHWEST
US.

...TIMING CLEARING AND TEMPS NEAR TERM WITH CHANCE LIGHT PRECIP LATE
WEEKEND AND THEN POTENTIAL MAJOR STORM MID WEEK MEDIUM CHALLENGE...

.DIAGNOSIS AND DAYS 1-3...ETA HANDLING OVERALL LOW CLOUDS BEST AND WILL
USE TO ADJUST TEMPS NEXT 24 HOURS.  THEN AVN/ETA BLEND LATE WEEKEND INTO
MONDAY.  LOW CLOUDS TO KEEP AREA ON HIGH SIDE OF LOWS TONIGHT WITH SOME
PATCHY LIGHT FOG POSSIBLE DUE TO LIGHT WINDS AND AVAILABLE MOISTURE.
SURFACE HIGH TO MOVE IN SATURDAY SO CLOUDY BEGINNING TO GIVE WAY TO
MOSTLY SUNNY SKIES IN AFTERNOON.  TEMPS WITH LOTS OF CLOUDS TIL LATE
AND SURFACE HIGH OVERHEAD WILL GO ON LOW SIDE OF BLEND.  THEN WITH SOME
HIGHER CLOUDS CENTRAL AND SOUTH WILL GO NEAR TO SLIGHTLY ABOVE AND
THEN SLIGHTLY BELOW NORTH WITH LIGHT WINDS AND MOSTLY CLEAR SKIES FOR
GOOD RADIATIONAL COOLING.  WILL GO LOW SIDE OF POPS LATE DAY SUNDAY INTO
SUNDAY NIGHT DUE TO WEAK OVERRUNNING FOR NOW BUT WILL NEED TO WATCH AND
SEE HOW ENERGY/MOISTURE FROM HURRICANE KERRI GETS INTEGRATED INTO
SOUTHWEST FLOW AND PASS TO NIGHT FOLKS TO MONITOR.  LOW LEVEL TEMPS AND
COOLING GROUND TEMPS SUPPORT FOR TYPE...LIGHT SNOW WITH SOME RAIN ALONG
HIGHWAY 20 AND LIGHT RAIN WITH SOME SNOW HIGHWAY 30 AND THEN PATCHY
LIGHT RAIN ALONG AND SOUTH OF INTERSTATE 80.   MONDAY...COOL AND PARTLY
CLOUDY WITH SURFACE HIGH NEAR TO OVERHEAD.

.EXTENDED (TUE-FRI)...VERY SERIOUS PATTERN SETTING UP MIDWEEK!  ALL THE
LARGE SCALE FACTORS SUGGEST MAJOR WINTER STORM TO DEVELOP IN THE MIDWEST
WITH AVNXT AND UKMET VERY SIMILAR AND STRONGEST.  CONCERN IS JUST ABOUT
EVERY TEXTBOOK TRIGGER IS INDICATED.  STRONG CANADIAN HIGH WITH LOTS OF
COLD AIR TO TAP...LOTS OF MOISTURE TO INCLUDE SUPER HURRICANE KERRI TO
PHASE WITH SYSTEM.  PHASING OF THREE MAJOR SHORT WAVES NEAR IOWA WITH
FUJIWARA EFFECT TO MAXIMIZE CYCLOGENESIS.  ALL INDICATIONS ARE OF AT
LEAST A 3 SIGMA TYPE SYSTEM (OR VERY STRONG TO POSSIBLY EXTREME
STRENGTH).  EVEN LATEST MODELS SUITE ARE STILL PLAYING CATCH UP WITH
STRENGTH OF SYSTEM (SEE AVNXT AND UKMET) WITH MODERATE UNCERTAINTY ON
EXACT TRACK AND RATE OF CYCLOGENESIS.  THE WINTER WEATHER THREAT
SUPPORTS UPDATING HWO.  RIGHT NOW...EXPECT 36-48 HOURS TO SEE MODEL
CONTINUE TO STRENGTHEN LOW AND ASSOCIATED HIGHER PRECIPITATION AMOUNTS
AND ALSO CONVERGE TO A GENERAL SOLUTION.  THIS LIKELY TO INCLUDE STRONG
WINDS ON BACKSIDE OF 35+ MPH AND THUS POTENTIAL BLOWING SNOW.  HWO WILL
EMPHASIZE POTENTIAL SEVERITY OF THIS UNUSUAL LATE OCTOBER SYSTEM.  FMR
AND MEX TEMPS ADJUSTED SIGNIFICANTLY TO ACCOUNT FOR STORM WITH WARMER ON
TUE AND THEN MUCH COLDER WEDNESDAY AND WELL BELOW THU/FRI.

COORDINATED WITH ILX...THANKS.

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

NICHOLS