150
FXUS63 KDLH 091208
AFDDLH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
608 AM CST TUE FEB 9 2010
AVIATION
UPDATE FOR 12Z TAFS
GRADUAL IMPROVEMENT FROM IFR/MVFR TO VFR DURING THE TAF PD FROM
W-E AS LOW PRESS SYSTEM MOVES OUT OF THE REGION. SN WILL END AS
WELL AS WINDS BACK FROM NE-N-NW. SEE BLO FOR SYNOP DISC.
PREV DISCUSSION
/ISSUED 354 AM CST TUE FEB 9 2010/
DISCUSSION...CWA REMAINS UNDERNEATH LARGE AMPLITUDE MID LVL
TROUGH THIS MORNING WITH CLOSED CENTER PUSHING WELL SOUTH OF
REGION INTO SW IOWA. CONTINUING CHALLENGE REMAINS ORIENTATION OF
BDRY LYR FLOW ACROSS LAKE SUPERIOR AND ASSOCIATED LAKE EFFECT SNOW
PLUMES. WELL ORGANIZED BAND YESTERDAY WORKED SOUTH ALONG NSHORE
DEPOSITING IN EXCESS OF A FOOT IN SEVERAL LOCATIONS. THIS BAND
MOVED INTO KDLH IN THE EVENING AND WEAKENED WHILE A SECONDARY BAND
FORMED FARTHER NORTH NEAR KTWM. BAND HAS ONCE AGAIN CONSOLIDATED
INTO A PRIMARY AXIS STRETCHING FROM LAKE SUPERIOR INTO NWRN
DOUGLAS COUNTY SOUTHWEST INTO SE CARLTON COUNTY. DIFFICULT TO GET
REAL TIME CONFIRMATION OF AMOUNTS/RATES AT THIS HOUR AND NO
WEBCAMS TO OFFER VISUAL SUPPORT. 88D RETURNS NEAR 30DBZ SUGGEST
AT LEAST 1"/HR RATES. SO LES WARNING LOOKS GOOD CERTAINLY FOR
DOUGLAS AT THIS TIME. WILL NEED TO LEAVE CARLTON/SRN ST LOUIS FOR
NOW AS BACK EDGE STILL AFFECTING CARLTON COUNTY. HAVE DROPPED SRN
LAKE COUNTY LES WARNING AS ORIENTATION OF SFC-85H FLOW IS BACKING
ENOUGH TO KEEP THREAT TO THE SOUTH AND EAST.
TODAY...ALTHOUGH WEAK SYNOPTIC SCALE ASCENT WILL OCCUR ACROSS SE
WISC ZONES...MAJORITY OF FORCING HAS LEFT THE AREA WITH DEPARTING
MID LVL SYSTEM. ABUNDANT SYNOPTIC SCALE MOISTURE WILL REMAIN
WITHIN THE 85/70H LAYER TO SUPPORT CONTINUATION OF MESOSCALE LAKE
EFFECT SNOW. THE MOST SIGNIFICANT ASPECT OF THIS EVENT SEEMS TO BE
THE VERY SLOW BACKING OF THE LOW LVL WIND FIELD IN RESPONSE TO THE
SFC HIGH TO THE NORTH AND THE SLOW MOVING LOW WELL TO THE SOUTH.
IN ESSENCE...THIS PROVIDES AN OPPORTUNITY FOR A PROLONGED PERIOD
OF LES POTENTIAL ACROSS THE SOUTH SHORE. THE INTENSITY OF THE BAND
OR BANDS IS STILL UNCERTAIN GIVEN MDL WEAKNESS IN FCST OF EXACT
LOW LVL WIND FLOW/SHEAR. ELSEWHERE...GRADUAL CLEARING WILL DEVELOP
ACROSS WRN CWA.
TONIGHT/TOMORROW...LES WILL CONTINUE ALONG SOUTH SHORE WITH POTENTIAL
FOR IMPRESSIVE TOTAL ACCUMULATIONS IF BANDS ORGANIZE. WIND WILL
SHIFT GRADUALLY INTO THE NORTH. THIS WILL ALLOW MORE SOUTHWARD
PENETRATION OF LAKE MOISTURE ACROSS NW WISC ZONES. BY 0Z WED...MID
LYR MOISTURE DROPS BELOW 60 PERCENT...LESSENING POTENTIAL FOR DEEP
GROWTH OF EXISTING LES PLUMES. COLDER AIR RETURNS THIS PERIOD WITH
TEMPS BELOW NORMAL MOST LOCATIONS EXCEPT OVER NW WISC AS AIR IS MODIFIED
AT LOW LEVELS FROM LAKE INFLUENCE.
WED NITE THRU MON...
WITH THE DEPARTURE OF CLOSED UPR LOW...A NW FLOW GETS RE-ESTABLISHED
OVR THE WRN GRT LKS FOR THE REMAINDER OF THE WEEK. MAIN QUES FOR THE
PERIOD WILL BE ANOTHER MORE COMPACT LOW SLIDING DOWN DURING THE
FRI/SAT TIME FRAME. NEW MODELS SHOWING MORE AGMT ON POSITION AND
MOVMT OF THIS FEATURE. LEFT IN SLGT POPS...BUT IF CURRENT MODEL
TRENDS CONTINUE...DAY SHIFT MAY HAVE TO INCRS THE POPS AND EXPAND
THE COVERAGE BOTH IN TIME AND AREA. WOULD LIKE TO SEE AT LEAST ONE
MORE MODEL RUN BEFORE DOING THIS HWVR. SFC RIDGING IN CONTROL FOR
THE EARLY PART OF NEXT WK. ANTICIPATE SUN/MON REMAINING DRY.
AVIATION.../06Z TAF ISSUANCE/
ANOTHER LAKE EFFECT SNOW BAND WORKING ITS WAY INTO DLH WITH BRIEF
IFR CONDITIONS POSSIBLE UNTIL 10Z. OTHERWISE MAINLY MVFR FOR THE
REST OF THE TAF SITES...WITH INL REMAINING VFR THROUGHOUT THE TAF
FORECAST PERIOD. HYR WILL BE NEARING IFR CONDITIONS LATER IN THE
MORNING.
POINT TEMPS/POPS
DLH 20 1 16 -1 / 50 10 0 0
INL 16 -11 13 -9 / 0 10 0 0
BRD 20 -9 15 -9 / 20 10 0 0
HYR 24 3 22 -16 / 90 40 10 0
ASX 24 12 21 -8 / 100 70 30 0
DLH WATCHES/WARNINGS/ADVISORIES
MN...LAKE EFFECT SNOW WARNING UNTIL NOON CST TODAY FOR MNZ037.
WI...LAKE EFFECT SNOW WARNING UNTIL MIDNIGHT CST TONIGHT FOR
WIZ001>003.
CANNON/04/BERDES
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