Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 031745 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1145 AM CST WED FEB 3 2016

.UPDATE...

SNOW SHOWERS OVER EAST CENTRAL AND SOUTHEAST WI CONTINUE TO WEAKEN
AS THEY TRACK EASTWARD LATE THIS MORNING. THESE SHOWERS ARE
ASSOCIATED WITH POSITIVE VORTICITY ADVECTION /PVA/ WITH THE MID
LEVEL TROUGH. IT IS AN INTERESTING SETUP IN THE UPPER LEVELS TODAY
SINCE THE MAIN UPPER LOW IS WEAKENING/SHEARING OFF OVER THE UPPER
MIDWEST THIS MORNING. THAT ROUND OF LIGHT TO MODERATE SNOW THIS
MORNING WAS DUE TO THAT PVA. AS THAT UPPER TROUGH WEAKENS OVER THE
UPPER GREAT LAKES THIS AFTERNOON... A SECONDARY WAVE OF ENERGY
ROUNDING THE BASE OF THE TROUGH WILL SLIDE THROUGH CENTRAL WI. THIS
WILL KEEP LIGHT SNOW SHOWERS POSSIBLE THROUGH THE REST OF THE DAY.

MOISTURE WILL BE SHALLOW THIS AFTERNOON... BUT DEEP ENOUGH TO TOUCH
THE LOWERING SNOW GROWTH ZONE ON COLD AIR ADVECTION. ONLY MINOR
ACCUMULATIONS... LESS THAN A HALF INCH... THIS AFTERNOON MAINLY
NORTH OF I-94.

&&

.AVIATION/18Z TAFS/...

CONDITIONS HAVE IMPROVED TO MVFR ACROSS MOST OF SOUTHERN WI LATE
THIS MORNING. EXPECT MVFR TO STICK AROUND THROUGH THE EVENING.
CLEARING SKIES SHOULD WORK THEIR WAY IN OVERNIGHT INTO THU MORNING.

EXPECT GUSTY NORTHWEST WINDS THIS AFTERNOON WITH THE POSSIBILITY FOR
LIGHT SNOW SHOWERS.

&&

.MARINE...

CANCELLED THE MARINE DENSE FOG ADVISORY EARLY SINCE WEBCAMS WERE
SHOWING IMPROVING VISIBILITY. WILL SEE NORTHWEST WINDS OF 15 TO 20
KNOTS AND GUSTS TO 25 KNOTS UNTIL MID EVENING WHEN WEAK RIDGE OF
HIGH PRESSURE BUILDS OVER THE NEARSHORE WATERS. A SMALL CRAFT
ADVISORY IS IN EFFECT.

&&

.PREV DISCUSSION... /ISSUED 435 AM CST WED FEB 3 2016/

SHORT TERM...TODAY THROUGH SATURDAY

TODAY...FORECAST CONFIDENCE MEDIUM.

DENSE FOG FORMED OVER MAINLY THE SOUTHERN HALF OF THE FORECAST AREA
IN THE BAGGY GRADIENT BETWEEN A PAIR OF SURFACE LOW PRESSURE
CENTERS...ONE DEVELOPING OVER LOWER MICHIGAN ON NOSE OF LOW-LEVEL
WARM ADVECTION AHEAD OF OCCLUDED FRONT THAT WILL EVENTUALLY BECOME
THE DOMINANT SURFACE FEATURE...AND THE ORIGINAL OCCLUDED SURFACE LOW
OVER EASTERN IOWA ASSOCIATED WITH SHORT WAVE ON LEADING FLANK OF 500
MB TROUGH. EXPECT THE FOG TO THIN AS NORTH WINDS INCREASE BUT WILL
MONITOR EASTERN LOCATIONS FOR A POSSIBLE EXTENSION WHERE WINDS COME
UP LATER.

IT IS THE FORCING ASSOCIATED WITH THIS SHORT WAVE THAT WILL BRING
LIGHT SNOW ACROSS THE CWA THIS MORNING AS IT SHEARS OUT AND LIFTS NE
WITH UPPER JET STREAK. SNOW...AND SOME MIXED PCPN...FROM CENTRAL TO
NE IOWA ALIGNING WITH LOW TO MID LAYER FRONTOGENESIS AND LOW TO MID
LAYER Q-VECTOR CONVERGENCE MAXES THAT WEAKEN AS THEY MOVE FROM SW WI
TO NE WI AS THE OCCLUDED LOW FILLS. WILL HAVE CATEGORICAL POPS FOR
LIGHT SNOW IN THE NW HALF OF THE CWA...POSSIBLY BRIEFLY MIXING
WITH SOME SLEET...WITH SOUNDINGS INDICATING A MIX OF RAIN AND SNOW IN
THE SE HALF WITH WARMER TEMPERATURES.

HAVE CANCELLED THE WINTER WEATHER ADVISORY EARLY AS TOTALS FROM THIS
ROUND OF SNOW WILL BE BELOW CRITERIA AS THE SHORT WAVE SHEARS OUT
AND BECOMES MORE PROGRESSIVE THROUGH OUR AREA AND THE SURFACE LOW IS
OPENING INTO A TROUGH THAT WILL TRAIL BEHIND THE DEVELOPING LOW OVER
LOWER MICHIGAN. EXPECT LIGHT SNOW TO TAPER TO SCATTERED SNOW
SHOWERS/FLURRIES AS TEMPERATURES COOL WITH INCREASING NORTH TO
NORTHWEST WINDS. OPEN AREAS MAY SEE SOME DRIFTING SNOW WITH GUSTY
WINDS.

TONIGHT...FORECAST CONFIDENCE HIGH.

ANY LINGERING SNOW SHOWERS/FLURRIES WILL BE GONE BY 00Z AS THE
SURFACE TROUGH PULLS AWAY AND HIGH PRESSURE BEGINS TO . COLD
ADVECTION DROPS OVERNIGHT LOWS INTO THE TEENS EAST AND SINGLE DIGITS
WEST AND NORTHWEST OF MADISON WITH THE DEEPER SNOW COVER. WINDS WILL
BE DIMINISHING WITH A WEAK RIDGE AXIS BUILDING OVER BY 12Z THURSDAY.

THURSDAY THROUGH SATURDAY...FORECAST CONFIDENCE MEDIUM.

A WEAK SFC RIDGE WILL MOVE EAST ON THU WITH AN APPROACHING SFC
TROUGH AND VORT MAX FROM MN. WEAK WARM ADVECTION AHEAD OF THESE
FEATURES WILL RESULT IN AN INCREASE OF CLOUDS INCLUDING SMALL
CHANCES OF LGT SNOW NW OF KMSN. THE WEAK WAA...PVA...AND LOW LEVEL
FRONTOGENESIS WILL THEN PROGRESS ACROSS SRN WI THU NT WITH SMALL
CHANCES OF LGT SNOW CONTINUING OVER THE NRN AND ERN CWA. AVA AND
CAA MAY CAUSE ENOUGH SUBSIDENCE TO SCATTER OUT THE CLOUDS LATE THU
NT AND FRI MORNING. THE CLOUDS HOWEVER WILL INCREASE ONCE AGAIN ON
FRI AS ANOTHER ROUND OF WEAK WAA AND PVA FROM AN APPROACHING UPPER
TROUGH AFFECTS THE REGION. SLIGHT CHANCES OF SNOW ARE FORECAST
OVER THE NRN CWA WITH THE AFOREMENTIONED FEATURES. THE TROUGH WILL
BE PASSED BY SAT WITH A COL OVER THE AREA. TEMPS WILL BE NEAR
NORMAL FOR THU-FRI RISING ABOVE NORMAL FOR SAT.

LONG TERM...SUNDAY THROUGH TUESDAY...FORECAST CONFIDENCE MEDIUM.

AN UPPER TROUGH WILL MOVE FROM THE NRN ROCKIES AND AMPLIFY OVER
THE MS RIVER VALLEY WITH CYCLOGENESIS OVER THE GREAT LAKES
THROUGH THIS PERIOD. THE SFC LOW PRESSURE AREA WILL SLOWLY MOVE
EWD ACROSS THE GREAT LAKES. THUS CHANCES OF LGT SNOW AND COLDER
TEMPS ARE FORECAST DURING THIS PERIOD.

AVIATION/12Z TAFS/...

IFR CONDITIONS WILL CONTINUE INTO THE EARLY AFTERNOON THEN LIFTING
TO MVFR AS WINDS INCREASE WITH PASSAGE OF WEAKENING SURFACE
LOW/TROUGH. TEMPERATURES WILL BE WARM ENOUGH FOR PCPN WITH THIS
LOW TO START OUT AS RAIN IN THE EAST...WITH A MIX OF RAIN AND SNOW
WEST. THE PCPN WILL TRANSITION TO ALL LIGHT SNOW IN THE WEST WITH
1 TO 2 INCHES NW OF MADISON...AROUND 1 INCH FROM FOND DU LAC TO
MADISON AND DARLINGTON...WITH 0.5 INCH OR LESS ELSEWHERE... WITH
MKE AND ENW ONLY SEEING A TRACE AT MOST.

ONCE THE SURFACE LOW/TROUGH PASSES TO THE EAST LATE THIS
MORNING...WEST WINDS AROUND 5 TO 10 KNOTS WILL SHIFT NORTHWEST AND
INCREASE TO 10 TO 20 KNOTS WITH GUSTS TO 25 KNOTS THROUGH THE REST
OF THE AFTERNOON. EXPECT CIGS TO LIFT TO MVFR WITH THE STRENGTHENING
WINDS...WITH VFR VSBYS AS THE PCPN COMES TO AN END. WEAK HIGH
PRESSURE WILL LOWER WINDS AND BRING VFR CIGS AND VSBYS AFTER 06Z
THURSDAY.

MARINE...

ISSUED A MARINE DENSE FOG ADVISORY FOR LESS THAN 1 MILE VSBYS OVER
THE NEARSHORE WATERS UNTIL 12 NOON. INCREASING WINDS WILL MIX OUT
THE FOG TO ABOVE 1 MILE BY THE NOON HOUR. WITH THE DELAY IN THE
INCREASING WINDS HAVE PUSHED BACK THE START TIME OF THE SMALL CRAFT
ADVISORY UNTIL 18Z. WILL SEE NORTHWEST WINDS OF 15 TO 20 KNOTS AND
GUSTS TO 25 KNOTS INTO THE EARLY EVENING WHEN WEAK RIDGE OF HIGH
PRESSURE BUILDS OVER THE NEARSHORE WATERS LOWERING WINDS.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 9 PM CST THIS EVENING FOR LMZ643>646.

&&

$$

UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...REM
THURSDAY THROUGH TUESDAY...GEHRING


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