Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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000
FXUS63 KMKX 110306 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1006 PM CDT WED SEP 10 2014

.UPDATE...

GUSTY NNW WINDS WILL SLOWLY EASE THROUGH THE OVERNIGHT AS THE
TIGHT PRESSURE GRADIENT RELAXES WITH THE DEEP SURFACE LOW OVER
LAKE HURON LIFTING AWAY TO THE NORTHEAST. IR SATELLITE IMAGERY
SUPPORTING LATEST NAM LOW-LEVEL RH FORECASTS THAT KEEP CLOUDS OVER
REGION INTO...AND POSSIBLY THROUGH THURSDAY AFTERNOON. THE CLOUD
COVER...ALONG WITH MIXING FROM THE WINDS...WILL PREVENT LOWS FROM
GOING EVEN LOWER THAN THE MID-40S FORECAST.

&&

.AVIATION/06Z TAFS/...

EXPECT MVFR CIGS TO CONTINUE THROUGH THURSDAY MORNING...WITH
EXPECTATION THAT DAYTIME HEATING AND DRIER AIR WORKING INTO REGION
WILL LIFT CIGS TO VFR LEVELS BY THURSDAY AFTERNOON...THEN SCATTER
OUT FROM SW TO NE BY LATE AFTERNOON. GUSTY NNW WINDS WILL SLOWLY
EASE OVERNIGHT BUT EXPECT 10 TO 20 KNOTS THROUGH DAYBREAK. WINDS
TURN NRLY BY DAYBREAK.

&&

.MARINE...

KEEPING END TIME TO SMALL CRAFT ADVISORY FOR THE TIME BEING...BUT
WITH THE FORECAST 10 TO 15 KNOT NORTH WINDS DOWN LONG AXIS OF
LAKE MAY KEEP WAVES UP IN THE 4 TO 5 FOOT RANGE LONGER THAN
FORECAST. WILL LET NEXT SHIFT ASSESS AFTER LOOK AT FULL 00Z DATA
SET AND EXTEND IF NECESSARY.

&&

.PREV DISCUSSION... /ISSUED 320 PM CDT WED SEP 10 2014/

TONIGHT...FORECAST CONFIDENCE - MEDIUM.

996 MILLIBAR SURFACE LOW LIFTING AWAY FROM DOOR PENINSULA. MUCH
COOLER AND DRIER AIR WRAPPING INTO SRN WI ON NW WINDS IN THE WAKE OF
THE DEPARTING LOW. SOME DECENT PRESSURE RISES SO WINDS WILL REMAIN
GUSTY FOR A WHILE THIS EVENING WITH THE TIGHTER GRADIENT SETTING UP.
CLOUD COVER IS EXTENSIVE THOUGH BETTER RETURNS WELL OFF TO OUR NORTH
AND NORTHEAST. A SHOWERS WILL LINGER INTO THE EVENING HOURS...MAINLY
IN ERN CWA. THAT SHOULD BE A WRAP ON THE PRECIP. WHILE SOME CLOUD
COVER MAY DIURNALLY DISSIPATE THE SHIELD IS EXTENSIVE AND RH PROGS
AND MOS SUGGEST QUITE A BIT OF THIS WILL HOLD TOGETHER...SO WILL
LEAN TOWARDS A TEMP DROPOFF THAT IS MORE TIED TO ADVECTION RATHER
THAN RADIATION.

THURSDAY...FORECAST CONFIDENCE...MEDIUM

COOL NORTHERLY FLOW AHEAD OF APPROACHING HIGH. GRADIENT RELAXES AS
THE DAY WEARS ALONG. STRONG WSW UPPER FLOW THOUGH ANY VORT IS
SHEARED AND WELL NORTH. EXPECT ANY CLOUD COVER TO GRADUALLY GO AT
LEAST BROKEN WITH SOME SUNSHINE. HARD TO EXPECT TOO MUCH SUN THOUGH
GIVEN THE PRONOUNCED NATURE OF THE 850 THERMAL POOL WITH READINGS OF
1C TO 5C. 925 TEMP REGIME SUPPORTS KEEPING MOST HIGHS IN THE
MID/UPPER 50S.

THURSDAY NIGHT THROUGH SATURDAY...FORECAST CONFIDENCE - MEDIUM.

LOW LEVEL WINDS VEER TO THE NORTHEAST THURSDAY NIGHT RESULTING IN
DECENT FETCH ACROSS LAKE MICHIGAN AS 85H TEMPS CONTINUE TO FALL TO 2-
3C.  AVERAGING NEARSHORE AND MID-LAKE SEA SURFACE TEMP RESULTS IN
SFC TEMP AROUND 15-16C.  HENCE DELTA-T INCREASES TO AROUND 15
DEGREES FRIDAY NIGHT.  NAM MORE AGGRESSIVE ON LOW LEVEL CONVERGENCE
OVER MILWAUKEE...RACINE AND KENOSHA LAKESHORE AREAS WHILE GFS WEAKER
AND FARTHER SOUTH.  ECMWF AND HIRES-ARW MORE IN AGREEMENT WITH
STRONGER NAM.  WL CONTINUE SMALL CHANCE FOR LAKE EFFECT -SHRA IN THE
FAR SOUTHEAST AND BUMP UP POPS SLIGHTLY RIGHT ALONG LAKESHORE FROM
MILWAUKEE SOUTH.

SOUTHERN WI WILL REMAIN ON THE NORTHERN EDGE OF A TIGHTENING LOW
LEVEL BAROCLINIC ZONE THAT WILL EXTEND FROM THE SOUTHERN PLAINS INTO
THE MID-MISSISSIPPI VALLEY.  FAIRLY POTENT MID-LEVEL SHORT WAVE WILL
MOVE FROM THE NORTHERN PLAINS ACROSS THE WESTERN GREAT LAKES ON
FRIDAY.  AHEAD OF THIS WAVE...INCREASING WESTERLY WINDS ALOFT WILL
TAP DEEPER MOISTURE IN THE NORTHERN PLAINS AND RESULT IN LOW
CONDENSATION PRESSURE DEFICITS ON THE 295 THETA SURFACE SPREADING
ACROSS SRN WI ON FRIDAY.  ISENTROPIC OMEGA WEAK HOWEVER ADDITIONAL
LIFT FROM LOW LEVEL FRONTOGENETICAL FORCING AND SYNOPTIC LIFT FROM
RIGHT ENTRANCE REGION OF UPPER JET GRAZING SOUTHERN WI.  HENCE
ENOUGH CONFIDENCE TO INCREASE POPS TO LIKELY IN THE WEST WHERE THESE
LIFT FEATURES COME INTO PHASE.  CLOUDS AND PRECIP WL KEEP TEMPS
QUITE COOL ON FRIDAY WITH MOST AREAS PEAKING IN THE LOW 50S...WHICH
WOULD BE 15 TO 20 DEGREES BELOW NORMAL FOR SEP 12.

ECMWF AND GEM SLOWER IN EWD PROGRESSION OF MID-LEVEL SHORT WAVE FRI
NIGHT...WHILE OTHER SHORT TERM GUIDANCE MORE PROGRESSIVE.  HENCE
CONFIDENCE LOW AT THIS POINT ON AMOUNT OF LATE NIGHT CLEARING
EXPECTED ACROSS SRN WI.  FOR NOW...WENT WITH FRIDAY NIGHT LOWS IN
THE UPPER 30S TO LOWER 40S AWAY FROM LAKE MI.  HOWEVER WITH 925H
TEMPS AROUND 5-6C...LIGHT LOW LEVEL WINDS AND MORE CLEARING WOULD
RESULT IN OVERNIGHT LOWS FALLING INTO THE MID 30S...AND A BETTER
CHANCE OF FROST.

SATURDAY LOOKS QUIET BUT COOL AS HIGH PRESSURE DRIFTS ACROSS THE
WESTERN GTLAKES.

SATURDAY NIGHT THROUGH WEDNESDAY...FORECAST CONFIDENCE - MEDIUM.

APPEARS COOLER WEATHER IS HERE TO STAY...AT LEAST THROUGH THIS
FORECAST PERIOD...WITH A CHANCE FOR -SHRA SUN NGT INTO MON.

UPSTREAM AMPLIFYING UPPER LEVEL RIDGE OVER THE EASTERN PACIFIC WL
MOVE SLOWLY EWD INTO THE WRN CONUS OVER THE WEEKEND THROUGH EARLY
NEXT WEEK.  THIS WILL RESULT IN A NORTHWEST UPPER LEVEL STEERING
FLOW ACROSS THE UPPER MIDWEST AND GREAT LAKES REGION...WITH AN END
RESULT OF A CONTINUATION OF BELOW NORMAL TEMPS.  THE CORE OF THE
COLDEST AIR ACCOMPANYING THE NORTHWEST FLOW WILL PASS ACROSS
WISCONSIN FRIDAY AND SATURDAY AS 85H TEMPS DROP TO AROUND ZERO.

THE COLDEST TEMPS WILL SLIDE OFF TO THE EAST ON SUNDAY AS THE LOW
LEVEL WINDS TURN TO THE SOUTHWEST AHEAD OF AN APPROACHING WEAK SHORT
WAVE TROUGH.  MEDIUM RANGE GUIDANCE IN REASONABLE AGREEMENT ON THIS
WAVE ADVANCING THROUGH WI LATER SUN NGT AND MON.  EXPECT ENOUGH
COLUMN MOISTURE TO BE IN PLACE TO CONTINUE CHANCE POPS FOR -SHRA.
INSTABILITY TO REMAIN NEGLIGIBLE SO WL HOLD OFF ON INTRODUCING ANY
T.  WEAK SHORT WAVE TO REMAIN PROGRESSIVE IN NORTHWEST FLOW AND WL
MOVE OFF TO THE EAST BY MONDAY NIGHT.  SLIGHTLY WARMER TEMPS ARE
THEN EXPECTED FOR TUE/WED.

AVIATION/00Z TAFS/...LOW PRESSURE SHIFTING NE OF WI. TIGHT GRADIENT
AND COLD AIR ADVECTION WILL DOMINATE TONIGHT. LOW CLOUD COVER LIKELY
TO STICK AROUND AND REMAIN AT MVFR LEVELS AT LEAST INTO THURSDAY
MORNING. GRADIENT GRADUALLY RELAXES THURSDAY AFTERNOON SO EXPECT
NORTH WINDS TO EASE A BIT.

MARINE...SURFACE LOW SHIFTING NE FROM NRN LAKE MI. GRADIENT
TIGHTENS UP WITH GUSTY SW WINDS SHIFTING NW THIS EVENING. HIGHEST
WAVES WILL GRADUALLY SHIFT MORE TOWARDS OPEN WATERS WITH MORE OF AN
OFFSHORE FLOW.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL NOON CDT THURSDAY FOR LMZ643>646.

&&

$$

UPDATE...REM
TONIGHT/THURSDAY AND AVIATION/MARINE...COLLAR
THURSDAY NIGHT THROUGH WEDNESDAY...MBK



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