Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 231549 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
949 AM CST FRI JAN 23 2015

.UPDATE...

AN AREA OF LOW PRESSURE TO OUR NORTH LOOKS TO SHIFT TOWARDS THE
EAST THIS AFTERNOON...SO KEEPING JUST LIGHT RAIN AND FLURRIES IN
OUR NORTHERN TIER OF COUNTIES. GUSTY SOUTHWEST WINDS WILL
INCREASE TEMPERATURES INTO THE MID TO UPPER 30S THIS AFTERNOON.
GUSTS WILL BE AROUND 20 MPH THIS AFTERNOON. WINDS WILL WEAKEN BY
THE EVENING...AND WILL TURN TO A MORE WESTERLY DIRECTION THIS
EVENING AND MORE NORTHWESTERLY DURING THE OVERNIGHT HOURS.

&&

.AVIATION/18Z TAFS/...

LOW LEVEL CLOUDS SITUATED OVER S WI HAVE REDUCED CIGS TO MAINLY
LOW END MVFR CONDITIONS...WITH CIGS NEAR 1000 FT. A DISTURBANCE
NORTH OF WISCONSIN LOOKS TO PIVOT EAST THIS AFTERNOON...KEEPING
PRECIPITATION NORTH OF THE AREA. WINDS WILL GUST NEAR 20 KTS OR
MORE IN SOME PLACES THIS AFTERNOON...BUT WEAKEN BY THE EVENING.
WINDS WILL TURN TOWARDS THE WEST AND NORTHWEST BY THIS EVENING AND
OVERNIGHT.

&&

.PREV DISCUSSION... /ISSUED 329 AM CST FRI JAN 23 2015/

TODAY AND TONIGHT...FORECAST CONFIDENCE - MEDIUM.

BACK EDGE OF EXTENSIVE STRATUS SHIELD MAKING SLOW BUT STEADY
EASTWARD PROGRESS. 05Z TAMDAR DESCENT SOUNDING INTO KRFD SHOWED THE
RH WAS SHALLOW...ONLY ABOUT 1K FT THICK.  INCREASING BOUNDARY LAYER
WINDS AND LOWERING INVERSION HEIGHT FROM SHORT TERM FORECAST
SOUNDINGS SHOULD RESULT IN CLEARING PROGRESSING STEADILY EWD AND MAY
EVEN ACCELERATE NEXT FEW HOURS.

OTHERWISE...EXPECT MID CLOUDS TO SURGE SOUTHWARD LATER THIS MRNG AND
AFTERNOON AHEAD OF WEAKENING MID-LEVEL TROF AND SURGE OF WARM AIR
ADVECTION AND ISENTROPIC OMEGA.  BOTH GFS AND NAM 295 THETA SURFACE
SHOWS NARROWING AREA OF ISENTROPIC OMEGA AND BRIEFLY LOWER
CONDENSATION PRESSURE DEFICITS SWEEPING ACROSS CWA DURING THE AFTN
AND EARLY EVE.  LAYER Q-VECTOR CONVERGENCE STEADILY WEAKENS AS THIS
FORCING MOVES ACROSS SRN WI.  HENCE WL BACK OFF TO 20 PERCENT POPS.
FORECAST SOUNDINGS ALSO SHOW INITIALLY DRY MID-LEVEL SO BETTER
CHANCE FOR LIQUID PRECIP AS WEAK FORCING SLIDES ACROSS CWA.
FORTUNATELY...SFC TEMPS ARE EXPECTED TO BE ABOVE FREEZING AT THIS
TIME...SO WL HOLD OFF ON ANY FREEZING PRECIP.

LINGERING LOW LEVEL MOISTURE THIS EVENING AND SECOND MID-LEVEL SHORT
WAVE MOVING ACROSS SRN WI MAY SHAKE OUT A FEW MORE LIGHT SHOWERS.
OTHERWISE STRATUS MAY FILL BACK IN DURING THE NIGHT IN INCREASING
NORTHWEST LOW LEVEL FLOW.

SATURDAY - CONFIDENCE...MEDIUM
LOW LEVEL THERMAL TROUGH GRADUALLY MODIFIERS WITH UPPER CYCLONIC
FLOW EASING INTO THE AFTERNOON HOURS. BUFKIT SOUNDINGS SHOW PRETTY
STRONG INVERSION ARND 5K FEET IN THE MORNING WITH DEPTH OF
MOISTURE DECREASING WITH TIME. SOME SATURATION MAKES IT INTO THE
DENDRIDIC GROWTH ZONE BUT JUST BARELY SUGGESTING ANY PRECIP THAT
OCCURS WOULD BE FLURRIES AND POSSIBLY TRANSITION TO A BIT OF
DRIZZLE. CONFIDENCE NOT GREAT THAT THIS OCCURS AND EXPECTING ANY
PRECIP TO BE QUITE LIGHT DUE TO NO FORCING IN THE LOW LEVELS AND
DRY AIR ALOFT. MODELS ARE ALL SHOWING A COUPLE OF DIFFERENT WEAK
VORT MAXES IN THE FLOW. WILL LEAVE DRY FORECAST INTACT BASED ON
COLLABORATION. SO GOOD DEAL OF CLOUD COVER EXPECTED WITH THE
LINGERING LOW LEVEL THERMAL TROUGH AND CYCLONIC FLOW.

SATURDAY NIGHT THROUGH SUNDAY NIGHT - CONFIDENCE...MEDIUM
00Z ECMWF HAS TRENDED FURTHER SOUTH WITH THE WELL ADVERTISED
CLIPPER SYSTEM. 00Z NAM IS SHOWING A NORTHERN SOLUTION WITH MORE
OF A MIXY POTENTIAL IN THE FAR SOUTH DUE TO LONGER DURATION OF
WARMER INFLUX SOUTH OF THE LOW TRACK. MEANWHILE GFS HAS BEEN
FAIRLY CONSISTENT WITH THE TRACK OF 850 LOW FROM NEAR DBQ TO NEAR
CHI. WPC IS LEANING MORE TOWARDS 00Z GFS AND 12Z ECMWF...WHICH WAS
IN CLOSER AGREEMENT. SO THAT WOULD PUT SRN WI IN MORE OF THE SWEET
SPOT THAN WHAT THE 00Z ECMWF AND 00Z NAM IS SHOWING. HAVE BOOSTED
POPS PER COLLAB WITH SURROUNDING OFFICES. GETTING SOLID 2-3 INCH
TOTALS FOR MUCH OF THE AREA. IF SUBSEQUENT SOLUTIONS TRENDS
TOWARDS THE ECMWF BETTER TOTALS WILL TREND FURTHER SOUTH. AFTER
SYSTEM SWINGS BY WINDS TURN ONSHORE WITH BORDERLINE DELTA T VALUES
BEING MET FOR A TIME SO HAVE CHC POPS IN THE FAR EAST TO ACCOUNT
FOR THIS INTO SUNDAY NIGHT WITH LIGHT ADDL ACCUMS.

MONDAY AND MONDAY NIGHT - CONFIDENCE...MEDIUM
WEAK FORCING SIGNAL WITH ELONGATED...MOSTLY SHEARED VORTICITY.
HOWEVER THERE IS SOME LOW LEVEL FORCING WITH WARM AIR ADVECTION
AHEAD OF NEXT SYSTEM. THIS TROUGH KEEPS LIGHT SNOW CHCS GOING INTO
MONDAY NIGHT.

TUESDAY - CONFIDENCE...MEDIUM
500 MILLIBAR CYCLONIC SHEAR AXIS SHIFTS EAST WITH HINTS OF LOW
LEVEL ANTICYCLONIC FLOW. WENT WITH AS DRY FCST.

WEDNESDAY - CONFIDENCE...MEDIUM
MID LEVEL RIDGING PROGD TO BECOME EVEN MORE PRONOUNCED AHEAD OF
NEXT APPROACHING SHORTWAVE TROUGH. DECENT WAA SO WITH SUNSHINE
SOME MILD TEMPS ON THE WAY...PUSHING 40.

WEDNESDAY NIGHT AND THURSDAY - CONFIDENCE...LOW
GFS AND EXTRAP OF GEM SUGGESTS WAVE WILL HAVE A BIT MORE OOMPH
THAN THE ECMWF WHICH SHOWS MORE OF A FAST MOVING OPEN WAVE. ECMWF
IS QUICKER TO COLLAPSE THE THERMAL RIDGE WHILE THE GFS SUGGESTS WE
COULD SQUEEZE OUT ANOTHER MILD DAY BEFORE FRONT DROPS IN. POSSIBLE
MIXY PRECIP TYPES WITH THE FRONT AND TRANSITIONING THERMAL FIELDS.

AVIATION/12Z TAFS/...MVFR STRATUS FIELD FLIRTING WITH IFR CIGS IN
A FEW LOCATIONS ACROSS SRN WI...HOWEVER INCREASING BOUNDARY LAYER
WINDS AND GRADUALLY LOWERING INVERSION SHOULD RESULT IN INCREASING
CIGS THIS MRNG. TAMDAR DESCENT SOUNDING INTO KRFD SHOWED MOISTURE
ABOUT 1K FT THICK AROUND 05Z. LOOKING FOR MVFR CIGS TO YIELD TO
VFR CONDITIONS LATER THIS MRNG. SURGE OF ISENTROPIC LIFT ALONG
MOVES ACROSS SRN WI THIS AFTN WHICH MAY CAUSE ISOLD -SHRA/-SHSN.
MVFR CIGS MAY RETURN TNGT IN INCREASING NW LOW LEVEL FLOW BUT LOW
LEVEL COLD AIR ADVECTION WEAK AND UPSTREAM LOW LEVEL RH LOOKS
MINIMAL AT THIS TIME.

MARINE...WILL CONTINUE SMALL CRAFT ADVY INTO THIS EVENING AS BLUSTERY
SOUTHWEST WINDS WILL CONTINUE THROUGH THE DAY DUE TO TIGHTENING
PRESSURE GRADIENT AS LOW PRESSURE PASSES TO THE NORTH OF THE
GTLAKES. GUSTS TO 25 KNOTS ARE LIKELY...ESPECIALLY AWAY FROM THE
SHORE. CURRENTLY SMALL CRAFT ADVY RUNS UNTIL 06Z BUT MAY BE ABLE TO
CANCEL A EARLIER IN THE EVE AS GRADIENT RAPIDLY WEAKENS LATE IN THE
EARLY EVE.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR LMZ643>646.

&&

$$

UPDATE...JTS
TODAY/TONIGHT AND AVIATION/MARINE...MBK
SATURDAY THROUGH THURSDAY...COLLAR



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