[LeArc] Forecast Discussion : MLI@ 2/17/03 1:34:47 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 170744
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
200 PM CST SUN FEB 16 2003

.OVERVIEW...LARGE WINTER STORM OVER EASTERN US THROWING WRAPAROUND
MOISTURE...ENHANCED BY LAKE MICHIGAN INTO EASTERN PORTION OF ZONES AT
07Z.  UPPER AIR AND SATELLITE SHOWING NEXT SHORT WAVE OVER PACIFIC
NORTHWEST TO HELP SLOWLY PUSH THIS MOISTURE EAST WITH WARMUP AS SFC
HIGH SLIDES EAST. LOTS OF COLD AIR IN CANADA NOTED WITH ACTIVE
PACIFIC JET FOR UNSETTLED PATTERN THIS WEEK.

...WARMUP NEXT COUPLE DAYS AND THEN POTENTIAL SIGNIFICANT SYSTEM ON
FRIDAY AND SATURDAY LONGER TERM ISSUE...

.DIAGNOSIS AND DAYS 1-3...ALL MODELS HAVING SOME PROBLEMS WITH LOW
CLOUDS WRAPPING BACK INTO AREA PAST FEW HOURS.  ETA SLIGHTLY BETTER
THAN OTHERS AND PLAN TO INCORPORATE IT WITH NOWCAST TOOLS FOR SLOW
CLEARING EASTERN 1/2 TO 2/3 AREA TODAY.  HIGHS WILL TREND NEAR TO
JUST ABOVE GUIDANCE TODAY WEST AREAS WITH MORE SUNSHINE AND SLIGHTLY
BELOW EAST SECTIONS.  TONIGHT WITH SOUTH WINDS AND PARTLY CLOUDY
SKIES...WILL START WARMUP WITH LOWS NEAR TO JUST ABOVE GUIDANCE
BLEND. PACIFIC AIR ARRIVES TUESDAY AND DESPITE SNOW-COVER...WILL SEE
TEMPS IN 40S THOUGH HEAVIEST SNOW COVERED AREAS WILL BE LOWER THAN
GUIDANCE TIL SNOW MELTS...SO PLAN TO ADJUST 1-2 CATEGORIES BELOW
BLEND. INTRODUCE SOME POPS OF SNOW AND RAIN SOUTH WEDNESDAY WITH WEAK
WAVE AS BOUNDARY AND MOISTURE RETURN TO SUPPORT SOME PRECIPITATION
CHANCES SOUTH OF HIGHWAY 34.

.EXTENDED RANGE(THU-SUN)...LATE WEEK SYSTEM LOOKING VERY SIGNIFICANT
AS ALL MODELS SUPPORT FAVORABLE LARGE SCALE FORCING AND PHASING
POTENTIAL WITH OPEN GULF AND ARCTIC AIR FOR WINTER STORM FRIDAY INTO
SATURDAY.  JET AXIS OF ALL MODELS SUGGEST MORE SNOW VERSUS RAIN
CHANCES...BUT UNCERTAINTY OF TRACK WILL KEEP RAIN AND SNOW WORDING IN
FOR NOW.  ADD RUN TO RUN CONSISTENCY AND SIZE OF SYSTEM...LIKELY
POPS WORDING VERY REASONABLE.  ECMWF IS THE STRONGEST WITH 985 MB SFC
LOW AND NEAR PERFECT TRACK FOR MAJOR SNOW EVENT...PUSHING NEAR
BLIZZARD CONDITIONS.   BOTH UKMET AND GFS-AVN ARE SIMILAR BUT WEAKER.
ALL LARGE SCALE FEATURES ARE CLEARLY EVIDENT...OPEN GULF AND PHASING OF
SOUTHERN PACIFIC ENERGY WITH NEXT ARCTIC AIR INCURSION FOR
STRENGTHENING SYSTEM (CYCLOGENESIS).  WILL PUT IN HAZARDOUS WEATHER
OUTLOOK (HWO) WITH NORMAL 5 DAY LONGER RANGE UNCERTAINTIES. SHOULD
HAVE A MUCH BETTER IDEA ON THIS SYSTEM NEXT 2-3 RUNS (TOMORROW NIGHT).
SIMILAR TYPE SYSTEMS WITH THESE TYPE PHASING ISSUES IN LATE WINTER
SUGGEST WATCH/WARNING CRITERIA VERY REASONABLE TO BE MET. SO...IF THIS
PLAYS OUT...MAY NEED TO EMPHASIZE THIS BY TOMORROW NIGHTS HWO.  TIL THEN
WILL TREND ON HIGH SIDE OF TEMP GUIDANCE WITH PACIFIC AIR AHEAD OF THIS
SYSTEM.

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

$$

NICHOLS