FXUS63 KDLH 020940
AFDDLH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DULUTH MN
340 AM CST WED DEC 2 2009

.DISCUSSION...SFC LOW HAS MOVED INTO CTRL UP OF MICH EARLY THIS
MORNING. A SECONDARY SFC TROF STRETCHES FROM THE SFC LOW WNW TO SE
MANITOBA. THIS IS A REFLECTION OF THE DEEP MID LVL TROF/LOPRES
LOCATED OVER NODAK. WITH THE MID LVL FEATURE AMPLIFYING
TODAY AS IT MOVES INTO SODAK...WOULD EXPECT SFC REFLECTION TO BE
MAINTAINED AS IT SLIPS SOUTH ACROSS CWA. COND PRESS DEFICITS
SUGGEST THAT ENOUGH SATURATION MAY OCCUR AT LOWEST LAYERS TO BRING
OCCASIONAL LT SN/FLURRIES TO WRN EDGE OF CWA. CONFIDENCE ON CLOUD
COVERAGE OVER CTRL CWA IS LOW AS MIXED SIGNALS DEVELOP. WILL
MAINTAIN CONTINUITY AND COLLABORATION WITH SURROUNDING OFFICES FOR
NOW AND ASSUME WHATEVER BREAKS THAT OCCUR WILL BE SHORT LIVED WITH
STEEPENING LAPSE RATES PROMOTING INSTABILITY CLOUDS. OTHERWISE
MAIN STORY WILL BE LAKE EFFECT SNOW DEVELOPING OVER SOUTH SHORE.
PRIMARY AREA OF INTEREST WILL BE ALONG GOGEBIC RANGE WHERE
ELEVATED TERRAIN WILL ENHANCE ACCUMULATIONS. BUFKIT INSTABILITY
PARAMETERS...USING ABOUT 6C FOR LAKE TEMP...ARE MARGINAL UNTIL
AFTER 6Z THUR. HOWEVER ...FAVORABLE SFC/85H TRAJECTORY ALIGNS
TODAY AS 85H TEMPS REACH LOW ENOUGH LVLS TO PROMOTE UNSTABLE
LAPSE RATES. LIMITING FACTOR MAY BE MARGINAL MOISTURE WITHIN
CRITICAL 85/70H LAYER...FAVORABLE THRESHOLD OF 60 PERCENT IS
QUESTIONABLE DEPENDING ON MDL SELECTION. WINDS SHIFT MORE NWRLY
THUR AFTERNOON WHICH SHOULD TEMPER INFLUX OF LL MOISTURE. WITH
CORE OF UPPER TROF PASSING OVERHEAD THURSDAY...DEEP CYCLONIC
CURVATURE SHOULD MAINTAIN ENOUGH MOISTURE TO HAVE SMALL POPS FOR
SNOW SHOWERS. 

.EXTENDED...THURSDAY NIGHT THROUGH TUESDAY
UPPER LOW WILL BE CENTERED JUST SOUTH OF HUDSON'S BAY...WITH 
CYCLONIC FLOW AND PLENTY OF MOISTURE PRESENT THURSDAY NIGHT. THE LOW 
STARTS TO MOVE SOUTH-SOUTHWEST ON FRIDAY...REACHING THE 
INTERNATIONAL BORDER ON SATURDAY. THE ECMWF AND GFS DIFFER ON THE 
LOCATION OF THE LOW BY THEN. HOWEVER...THEY BOTH SHOW A SURFACE 
TROUGH EXTENDING NORTHEAST THROUGH SOUTHERN MINNESOTA OVER LAKE 
SUPERIOR. THE EXACT ORIENTATION OF THIS TROUGH WILL HAVE A BIG 
IMPACT ON THE WEATHER...ESPECIALLY FOR THE THE TWIN PORTS AREA. IF 
THE GFS IS CORRECT...THE TWIN PORTS AND A PORTION OF THE SOUTH SHORE 
COULD GET LAKE EFFECT SNOW DURING THE WEEKEND AS 850MB TEMPS ARE 
FORECAST TO BE FROM -12C TO -14C. 

WE DID NOT MAKE SIGNIFICANT CHANGES TO THE EXTENDED AT THIS TIME. WE 
HAVE CHANCES FOR LIGHT SNOW THURSDAY NIGHT INTO FRIDAY NIGHT...WITH 
MOST LOCATIONS NOT SEEING TOO MUCH ACCUMULATION. WE ALSO DID NOT ADD 
POPS TO FAR WESTERN LAKE SUPERIOR FOR THE WEEKEND...DUE TO MODEL 
DISAGREEMENT...BUT WE WILL WATCH CLOSELY. THE REST OF THE EXTENDED 
WAS UNCHANGED AS WELL. 

TEMPERATURES WILL BE SEASONAL.

.AVIATION...06Z TAF ISSUANCE
WIDESPREAD MVFR CIGS ARE EXPECTED DURING THE TAF PERIOD. THROUGH
THE EARLY MORNING HOURS...SOME LOCALIZED IFR/LIFR CIGS/VSYBS WILL
BE POSSIBLE DUE TO SOME SNOW...ESPECIALLY ACROSS NORTHERN TAF
SITES. CONDITIONS SHOULD GENERALLY BE DRY DURING THE DAY ON
WEDNESDAY...WITH MVFR CIGS BEING THE RULE. 

&&

.POINT TEMPS/POPS...
DLH  29  16  20  12 /  10  10  20  20 
INL  26  12  16  12 /  10  10  20  40 
BRD  31  18  23  12 /  20  20  20  20 
HYR  32  17  22  14 /  20  30  20  20 
ASX  33  19  22  18 /  30  40  40  20 

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...NONE.
WI...LAKE EFFECT SNOW ADVISORY FROM 4 PM THIS AFTERNOON TO 4 PM CST 
     THURSDAY FOR WIZ003-004.

LS...SMALL CRAFT ADVISORY UNTIL NOON CST THURSDAY FOR LSZ121-146>148.

     SMALL CRAFT ADVISORY UNTIL NOON CST TODAY FOR LSZ140>145.

&&

$$

CANNON/MELDE