FXUS63 KDLH 252328
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
528 PM CST WED NOV 25 2009
.UPDATE...FOR 00Z TAFS
&&
.AVIATION...UPDATE FOR 00Z TAFS
IFR/MVFR CIGS WILL CONT THRU THE REST OF THE NIGHT AS RA/SN ENDS
WITH DEPARTURE OF SFC LOW OVR NRN LWR MI AND HIGH PRESS MOVES IN
FROM THE W. CIGS WILL BREAK OUT TO VFR THU MRNG AS DRIER AIR AND
SUBSDC INVADES THE REGION. VSBYS SHUD REMAIN VFR THRU THE TAF PD.
&&
.PREV DISCUSSION... /ISSUED 326 PM CST WED NOV 25 2009/
DISCUSSION...MSAS INDICATES SFC LOW OVER NRN LK MI UNDERNEATH
EJECTING MID LVL TROF WHILE SECONDARY...MORE INTENSE CLOSED MID
LVL LOW PUSHES SOUTH ACROSS CTRL IA. DEEP CYCLONIC CIRCULATION
PREVAILS ACROSS CWA WITH MAIN PRECIP AREA ALIGNED FROM ERN
ARROWHEAD SOUTH TO NW WISC. AREA OF FRONTOGENESIS PREVIOUSLY
LOCATED WITHIN 950/750 LAYER APPEARS TO HAVE DIMINISHED. WIND FLOW
IN RUC13 SFC/85H LAYER HAS INCREASED ENOUGH THAT A STANDING WAVE
MAY INITIATE FOR A FEW HRS LATE THIS AFTERNOON/EVENING ACROSS NRN
DOUGLAS INTO SE CARLTON COUNTIES. ENOUGH MOISTURE IN LOW LAYERS TO
GENERATE SOME INCREASED POPS THRU 6Z PERHAPS SO MAY SEE SOME MINOR
SN ACCUMULATION. EXPECT PROGRESSIVE NATURE OF MID LVL FLOW TO KEEP
SYSTEM MOVING EAST OVERNIGHT. A MORE FAVORABLE TRAJECTORY FOR
LAKE ENHANCED SNOW WILL COMMENCE THIS EVENING ACROSS LAKE SUPERIOR
INTO GOGEBIC RANGE. WATER TEMP NEAR 7C AND 85H NEAR -4/-6C
OVERNIGHT..SO LAKE INDUCED INSTABILITY INCREASES SOMEWHAT. SYNOPTIC
SCALE RH... WITHIN CRITICAL 70/85H LAYER... FALLS BELOW 6O PERCENT
THRESHOLD BY 18Z THUR SO MOST ACTIVITY SHUTS DOWN. MID LVL
RIDGING/SFC HIGH EDGE EASTWARD NEXT 24 HRS SO EXPECT QUIET PATTERN
OVERALL. SHOULD SEE SOME MID LVL WARM ADVECTION CLOUDS WORK ACROSS
NRN HALF OF REGION THUR NIGHT INTO FRIDAY. ISENTROPIC ASCENT
INCREASES ACROSS REGION FRIDAY HOWEVER RELATIVELY DRY LAYERS AND
HIGH COND PRESS DEFICITS IN LOWEST 10K FT SUGGEST DRY FCST TO
CONTINUE. MODEL DIFFERENCES INCREASE AS THE WEEKEND BEGINS. GFS/EC
IN DECENT AGREEMENT WHILE SREF/GEM FARTHER NORTH. WILL KEEP FCST
DRY FOR NOW UNTIL MORE CONSENSUS ARRIVES TO WARRANT CHANGE.
EXTENDED...SATURDAY NIGHT THROUGH WEDNESDAY. A LOW PRESSURE SYSTEM
IS EXPECTED TO BE OVER IOWA BY THE START OF THIS PERIOD...WITH SOME
SEMBLANCE OF AN INVERTED TROUGH EXTENDING NORTHWARD INTO THE CWA.
THE ECMWF IS NOT QUITE AS DISTINCT WITH THIS INVERTED TROUGH AS THE
GFS. A SHORTWAVE PUSHING IN FROM THE DAKOTAS WILL ALSO HELP TO
GENERATE A BAND OF LIGHT SNOW ACROSS FAR NORTHERN MN AT THE START OF
THE PERIOD. THIS BAND SHOULD THEN PROPOGATE AND EXPAND SOUTHWARD
SATURDAY NIGHT INTO SUNDAY AS THE SHORTWAVE DIGS SOUTHWARD INTO THE
WESTERN GREAT LAKES. THE SHORTWAVE WILL USHER IN COOLER WEATHER FOR
THE WEEKEND AND EARLY IN THE WORK WEEK...BEFORE RETURN FLOW DEVELOPS
EARLY TO MID NEXT WEEK.
AVIATION...CLOUD COVER WILL BE HIGHLY VARIABLE ACROSS THE AREA
OVERNIGHT. THE NIGHT WILL START WITH A CLEAR SPOT OVER THE BRAINERD
LAKES REGION...BUT WIDESPREAD MVFR WILL BE FOUND ELSEWHERE. IN
FACT...SOME LOCALIZED IFR/LIFR CIGS/VSBYS WILL BE POSSIBLE IN SPOTS.
AS THE NIGHT WEARS ON...CLOUDS ARE EXPECTED TO CLEAR OUT FOR MOST
AREAS AS STRONG SUBSIDENCE DEVELOPS WEST OF THE AREA AND PUSHES
EASTWARD.
&&
.POINT TEMPS/POPS...
DLH 24 34 21 35 / 10 10 10 0
INL 19 30 21 34 / 10 10 0 10
BRD 24 35 24 37 / 10 0 0 0
HYR 28 35 24 37 / 40 20 0 0
ASX 30 37 26 37 / 50 30 10 0
&&
.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...NONE.
LS...SMALL CRAFT ADVISORY UNTIL 10 PM CST THURSDAY FOR LSZ121-146>148.
&&
$$
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