FXUS63 KDVN 042140 CCA
AFDDVN
AREA FORECAST DISCUSSION...CORRECTED TYPOS EXTENDED
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
333 PM CST FRI NOV 4 2009
.SYNOPSIS...
A HIGHLY AMPLIFIED H5 PATTERN WAS IN PLACE OVER THE NOAM THIS
MORNING. A SHARP RIDGE WAS LOCATED OVER THE EASTERN PACIFIC INTO
THE ALEUTIANS WITH A VIGOROUS S/W DROPPING DOWN THE BACK SIDE
OF THE RIDGE THROUGH BC. THE S/W WAS HEADED TOWARD A DEEP TROF
THAT ORIGINATED FROM AN UPPER LOW OVER ONTARIO AND EXTENDED SOUTH
THROUGH NRN MEX. COLD SURFACE HIGH PRESSURE WAS LOCATED FROM THE
SOUTHERN PLAINS THROUGH THE OHIO VALLEY WITH A DEVELOPING SURFACE
LOW OVER THE NRN PLAINS. DEEP CYCLONIC FLOW AROUND THE ONTARIO LOW
WAS SUPPORTING WIDESPREAD FLURRY AND SN SHOWERS OVER MUCH OF THE
UPPER MIDWEST...INCLUDING THE MID MS VALLEY THIS AFTERNOON.
&&
.SHORT TERM...TONIGHT AND SATURDAY...
MAIN CONCERN FOR THE NEXT 24 HOURS WILL BE THE TIMING OF THE
CLEARING TONIGHT. SOLID SC IS IN PLACE OVER THE NRN CWFA THIS
AFTERNOON WITH MORE CUMULIFORM CLOUDS TO THE SOUTH. THE NAM SEEMS
TO CAPTURE THE AREAL EXTENT OF THE CLOUDS BASED ON ITS H8 RH
PROGS...BUT IT LOOKS LIKE IT HOLDS ON TO THE CLOUDS TO LONG THIS
EVENING. FEEL THE CU OVER THE SRN IA/NRN MO WILL DISSIPATE BY EARLY
EVENING LEAVING JUST THE SOLID SC OVER THE NRN CWA. THROUGH A
COMBINATION OF THE WESTERLY LOW LEVEL FLOW AND SUBSIDENCE BEHIND A
DEPARTING MID LEVEL TROF...THE NRN SC SHOULD BREAK UP AS THEY MOVE
EAST OUT OF THE CWA LATE EVENING OR EARLY SATURDAY MORNING. HAVE
ALSO HELD ONTO SOME FLURRIES OVER THE NRN HALF FOR THIS EVENING.
BASED ON THIS TIMING HAVE KEPT TEMPS CLOSE TO THE MET GUIDANCE.
RETURN FLOW WILL BE WELL ESTABLISHED OVER THE CWFA SATURDAY AHEAD OF
A COLD FRONT MOVING THROUGH THE NRN PLAINS. EXPECT MOSTLY SUNNY
SKIES FOR SATURDAY. HIGHS IN THE 30S WERE BASED ON MIXING TO
925MB. ..DLF..
.LONG TERM...SATURDAY NIGHT THROUGH NEXT FRIDAY...
IMPRESSIVE BAROCLINIC ZONE... JET AND ENERGY DUMP INTO THE WEST ALL
COMING TOGETHER FOR VERY ACTIVE/UNSETTLED PATTERN THROUGH THE PD.
IMPRESSIVE BAROCLINIC ZONE TO BECOME ESTABLISHED RIGHT THROUGH THE
CENTRAL CONUS... BETWEEN ARCTIC AIR WITH 1040+ MB HIGH BUILDING
SOUTH THROUGH THE NORTHERN ROCKIES AND NORTHERN PLAINS AND SUBTROPICAL
WARMTH ALONG GULF COAST. IT/S THIS BATTLE ZONE THAT WILL SERVE AS
STORM TRACK IN WHICH AREA WILL RESIDE... AWAITING BOUTS OF ENERGY
EJECTING FROM WESTERN TROUGH. IT APPEARS AS THOUGH THREE STORM SYSTEMS
HAVE AREA IN THE CROSS HAIRS.
FIRST SYSTEM...MAINLY SUN NGT LINGERING INTO EARLY MON.
FAST MOVING SHORTWAVE WITH FAVORABLE JET DYNAMICS WITH LIFT FROM LEFT
EXIT REGION... AND MID LEVEL FRONTOGENETICAL BAND TO PRODUCE
QUICK HITTING ROUND OF ACCUMULATING SNOWS. LIMITED MOISTURE AND FAST
NATURE OF SYSTEM TO LIMIT ACCUMS TO MAINLY 1-2 INCH AMOUNTS WITH
POTENTIAL FOR FEW 3 INCH AMOUNTS. LOCATION OF FORCING (FRONTOGENESIS...
UPPER DIVERGENCE... WARM ADVECTION AND TRACK OF SFC-H85 CIRCULATIONS)
ALL STILL SUPPORT BEST ACCUMS WITH SYSTEM ROUGHLY BETWEEN HWY 20 TO
NEAR I-80.
SECOND SYSTEM...TUE PM THROUGH WED.
STRONG SIGNAL REMAINS FOR SIGNIFICANT/MAJOR WINTER STORM WITH ALL MAIN
PLAYERS WITH BAROCLINIC ZONE REALLY IMPRESSIVE AND PEAKING DURING
PD... AND STRONG JET AND POTENT ENERGY IN WEST. HOWEVER... THE DEVIL
IS IN THE DETAILS... IN THIS CASE STRENGTH AND TRACK OF SYSTEM... WHICH
IS TIED TO PHASING AND WHERE MODELS CONTINUE TO HAVE FITS. GFS NOW
BACK TO YESTERDAY/S 12Z AND 18Z SOLUTIONS OF FURTHER WEST PHASING WITH
POTENT NEG TILT SHORTWAVE TROUGH LIFTING THROUGH MID MISSISSIPPI VALLEY
ON WED. ECMWF MEANWHILE HAS GONE AWAY FROM PHASING TIL EAST OVER THE
OH VALLEY AND INSTEAD OF 979 MB SFC LOW OVER LAKE MI 12Z WED NOW
992 MB LOW SOUTHERN OH... WHICH GOES ON TO DEEPEN OVER THE EASTERN CONUS.
12Z UKMET FAIRLY CLOSE TO ECMWF THOUGH WEAKER WITH 1000 MB LOW OVER
KY/TN. MOST OF THE 12 GFS ENSEMBLE MEMBERS (04/12Z) SIDING TOWARD THE
WEAKER AND FURTHER SOUTH SOLUTIONS ADVERTISED BY TODAY/S 12Z ECMWF
AND UKMET. THESE DIFFS IN STRENGTH TO HAVE BIG IMPACTS ON PCPN AMOUNTS
AND LOCATION... AND POSSIBLY EVEN PTYPE AS STRONGER SYSTEM LIKELY
TO TRACK FURTHER NW BRINGING WARMER AIR NWD AND THREAT OF WINTRY MIX SE
SECTIONS. BOTTOM LINE IS STORM WITH POTENTIALLY SIGNIFICANT IMPACTS
IN TERMS OF HEAVY SNOW (6+ INCHES) AND STRONG WINDS STILL BEING SUGGESTED
JUST PLENTY OF UNCERTAINTY REMAINS AS TO WHERE/TRACK AND MAGNITUDE TO BE
BETTER CLARIFIED NEXT 24 HRS.
THIRD SYSTEM...LATE THU/FRI POSSIBLY INTO SAT.
MEDIUM RANGE COMING INTO BETTER AGREEMENT ON ADVERTISING ANOTHER SYSTEM
BEHIND MID WEEK STORM WITH POTENTIAL FOR MORE ACCUMULATING SNOW. LOTS
OF CHALLENGES OF COURSE THOUGH WITH STRENGTH... TIMING AND TRACK WITH
IMPACTS FROM DEPARTING SYSTEM. FOR NOW HAVE INTRODUCED SMALL POPS THU NGT
INTO FRI.
AS FOR TEMPS...WILL BE NEAR TO BELOW NORMAL DURING PD. POTENTIAL FOR ARCTIC
AIR BY MIDWEEK IF MORE PHASED/STRONGER SOLUTION OCCURS... WHICH WITH
NEGATIVE FEEDBACK FROM SNOW COVER WOULD RESULT IN MUCH BELOW NORMAL TEMPS.
..M^2..
&&
.AVIATION...
AREA OF SOLID MVFR CIGS WILL MOVE EAST OF KDBQ BY LATE EVENING. SCT
-SHSN WILL BE ASSOCIATED WITH THE CLOUDS. VSBYS IN THE -SHSN WILL BE
GENERALLY AOA 6SM BUT BRIEF PERIODS OF 3-5SM VSBYS ARE POSSIBLE.
CUMULIFORM CLOUDS OVER KMLI/KCID/KBRL SHOULD DISSIPATE WITHIN A
COUPLE HOURS AFTER SUNSET. OTHERWISE VFR CONDITIONS EXPECTED THROUGH
18Z SATURDAY. WESTERLY SFC WINDS THIS EVENING WILL TURN SOUTHERLY
LATE TONIGHT AND SATURDAY MORNING.
&&
.DVN WATCHES/WARNINGS/ADVISORIES...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
DLF/M^2
