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000
FXUS63 KMKX 122146
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
346 PM CST THU DEC 12 2013

.SHORT TERM...

.TONIGHT...FORECAST CONFIDENCE HIGH.

HIGH CLOUDS WILL STREAM BACK INTO SOUTHERN WI THIS EVENING WITH AN
APPROACHING WEAK SHORTWAVE. HIGH LEVEL MOISTURE IN THE UPPER LEVELS
WILL LEAD TO HIGH CLOUDS OVER THE REGION THROUGH FRIDAY. EXPECT
TEMPS TO DROP INTO THE 10 TO 15 DEGREE RANGE IN THE EVENING AND
REMAIN FAIRLY STEADY OVERNIGHT. A WEAK SURFACE COLD FRONT WILL DROP
SOUTH THROUGH THE AREA LATER TONIGHT. THIS WILL HELP SET THE STAGE
FOR THE EASTERLY FLOW ACROSS THE LAKE.

.FRIDAY...FORECAST CONFIDENCE MEDIUM.

THERE COULD BE SOME FLURRIES ACROSS THE NORTHERN MKX FORECAST AREA
FRIDAY MORNING WITH A WEAK CLIPPER MOVING ACROSS NORTHERN WISCONSIN.

THEN WE WAIT FOR SURFACE WINDS TO BECOME NORTHEAST TO EAST. THE
UPPER LEVELS LAG BEHIND WITH THE TRANSITION. DURING THE
AFTERNOON...EXPECT 1000-850MB TOTAL WIND TO COME AROUND TO ENE. WITH
INCREASING RH IN THAT LAYER...EXPECT LAKE EFFECT SNOW SHOWERS TO
DEVELOP OVER THE SHORELINE AT SHEBOYGAN AND DOWN THROUGH AT LEAST
RACINE. SURFACE WINDS ARE EXPECTED TO REMAIN ESE AROUND KENOSHA.

MANY 12Z MODELS AND ARE FOCUSING THE DEVELOPMENT OF A PRIMARY LAKE
EFFECT SNOW BAND SETTING UP OVER MILWAUKEE COUNTY IN THE CONVERGENCE
ZONE BETWEEN THE ESE AND ENE WINDS BEGINNING LATE FRIDAY AFTERNOON
OR RIGHT AROUND 00Z. HIGH SNOWFALL RATES COULD OCCUR BENEATH THIS
BAND. THERE IS UNCERTAINTY ABOUT EXACTLY WHERE IT WILL SET UP AND
EXACTLY WHAT TIME. IT MAY PUSH ONSHORE AFTER THE RUSH HOUR PERIOD IS
OVER. WILL HIGHLIGHT THE THREAT OF THIS SNOW BAND IN THE HWO AND A
SPECIAL WEATHER STATEMENT. IF MODELS CONTINUE TO SHOW THIS
BAND...A LAKE EFFECT SNOW ADVISORY WILL BE CONSIDERED.

IN ADDITION...EXPECT MULTIPLE LIGHTER BANDS OF SNOW NORTH OF
MILWAUKEE UP TO SHEBOYGAN WITH THE LONGER NORTHEAST FETCH OVER THE
LAKE BEGINNING FRIDAY AFTERNOON. WITH THE EASTERLY FLOW...ALL OF
THESE LAKE EFFECT SNOW BANDS CAN EXTEND INLAND AT LEAST ONE TIER OF
COUNTIES.

.FRIDAY NIGHT THROUGH SATURDAY NIGHT...FORECAST CONFIDENCE MEDIUM
TO HIGH.

ACTIVE PERIOD...WITH FORECAST CONCERNS REVOLVING AROUND LES AND
LARGER SCALE SYNOPTIC SNOW/LAKE ENHANCEMENT SNOW. DETERMINISTIC
MODELS GENERALLY CONSISTENT WITH THE PREVIOUS RUN. 500 HPA FLOW
MAINLY OUT OF WEST...WITH AN UPPER LEVEL TROUGH AND VORT MAX
BEGINNING TO DROP AND ROTATE THROUGH LATE IN THE PERIOD WITH 10-15
DAM HT FALLS OUT AHEAD. OTHERWISE...MODELS KEEP THE SURFACE LOW
PRESSURE SYSTEM TO OUR SOUTH AS SEEN PREVIOUSLY...WITH AN INVERTED
TROUGH THEN MOVING THROUGH AND THEN PIVOTING NEAR SOUTHERN LAKE
MICHIGAN.

NOT MUCH IN TERMS OF BROAD SCALE ASCENT/SYNOPTIC SUPPORT. THIS
COMBINED WITH THE POSITION OF THE LOW...EXPECT THE MAJORITY OF
SYNOPTIC SNOW TO BE SOUTH OF THE FORECAST AREA THOUGH WILL STILL
SEE A SYNOPTIC CONTRIBUTION. OTHERWISE...DECENT LOW-LEVEL OMEGA
AND LOW-LEVEL CONVERGENCE IS PRESENT WITH VERY CONDUCIVE WIND
FIELDS FOR LES. THE BEST CHANCES FOR SNOW EXIST LATE FRIDAY INTO
SATURDAY WITH LAKE EFFECT DELTA TS GENERALLY AROUND 15-18 C AND
EAST WINDS PRESENT. WIND DIRECTION BETWEEN 1000-850 HPA DOESNT
CHANGE MUCH SATURDAY...SO SHOULD BE EFFICIENT IN REGARD TO
FOCUSING THE SNOW IN THE SAME AREA FOR A TIME. REGARDING TEMPS
ALOFT...850 HPA TEMPS A LITTLE MORE MILD THAN PREVIOUSLY
SEEN...AROUND -9 TO -13 C...WITH LAKE MICHIGAN WATER TEMPS IN THE
UPPER 30S AND LOW 40S. OTHER CONSIDERATION IS THE HEIGHT OF THE
CAPPING INVERSION AND DEPTH OF THE MIXED LAYER...OF WHICH JUST
ABOVE OR AROUND 4000 FT GENERALLY. SO CONVECTIVE DEPTH IS
SUFFICIENT. CONCEPTUALLY...MULTIPLE HORIZONTAL BANDS ARE
ANTICIPATED PERPENDICULAR TO SHORE AND FOR THE LES TO THEN
CONGEAL. MODELS WERE IN GOOD AGREEMENT IN PRODUCING QPF ACROSS THE
CWA AND A GENERALLY CONSISTENT LES SIGNAL IS PRESENT. SNOW AMOUNTS
OVERALL WERE NOT CHANGED TOO MUCH. SNOW TOTALS RANGE FROM 4 TO 6
INCHES IN THE NORTH EAST AND EAST CENTRAL COUNTIES OF THE CWA AND
THEN DECREASE WESTWARD.

.LONG TERM...

.SUNDAY THROUGH THURSDAY...FORECAST CONFIDENCE LOW TO MEDIUM.

A BIT OF A SHORT REPRIEVE SUNDAY BEFORE A CLIPPER-SYSTEM BRINGS
INCREASING SNOW CHANCES MONDAY AND EARLY TUESDAY. THIS IS
FOLLOWED BY THE DETERMINISTIC MODELS THEN FALLING OUT OF
AGREEMENT. OF WHICH...GFS AND ECMWF HAVE TWO DIFFERING
SOLUTIONS...THE FORMER SHOWING THE INFLUENCE OF HIGH PRESSURE ON
WISCONSIN WHILE THE LATTER BRINGS A SFC LOW TOWARDS/THROUGH
WISCONSIN THURSDAY. AS WELL...THE 500 HPA PATTERN DIVERGES
GREATLY HERE. THUS...THE PERIOD IS VERY MUCH UNSETTLED AND A
CONSENSUS APPROACH WAS TAKEN IN THE LONG-TERM/EXTENDED. HIGH
TEMPERATURES ARE ANTICIPATED TO STAY BELOW THEIR SEASONAL NORMAL
VALUES IN THIS PERIOD...BUT MAY APPROACH THESE VALUES TUESDAY.

&&

.AVIATION/00Z TAFS/...

WINDS WILL DIMINISH TONIGHT...THEN SHIFT AROUND TO THE EAST
NORTHEAST FRIDAY MORNING IN THE WAKE OF THE PASSING FRONT.

NORTHEAST WINDS NORTH OF MILWAUKEE AND ESE WINDS SOUTH OF MILWAUKEE
COULD LEAD TO A CONVERGENCE ZONE OVER THE LAKE. SEVERAL MODELS ARE
POINTING TO A CONVERGENT LAKE EFFECT BAND SETTING UP OVER MILWAUKEE
COUNTY LATE FRIDAY AFTERNOON AND EVENING. THIS WOULD HAVE POTENTIAL
TO PRODUCE HIGH SNOWFALL RATES AND REDUCED VISIBILITY. MKE AND MWC
AIRPORTS COULD BE IMPACTED. STAY TUNED AS WE GATHER MORE CONFIDENCE
ABOUT LOCATION AND TIMING.

IN ADDITION...EXPECT SMALLER LAKE EFFECT BANDS TO AFFECT ALL
SHORELINE AREAS FROM FRIDAY AFTERNOON THROUGH SATURDAY MORNING.
THESE COULD BRING BRIEF PERIODS OF HIGHER SNOWFALL RATES.

&&

.MARINE...

THE NEXT CHANCE FOR SMALL A SMALL CRAFT ADVISORY WILL BE FRIDAY
NIGHT INTO SATURDAY MORNING AS LOW PRESSURE MOVES NORTHEAST THROUGH
THE OHIO VALLEY. THE EAST TO NORTHEAST WINDS WILL GENERATE LARGE
WAVES ON THE WESTERN SIDE OF LAKE MICHIGAN.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&

$$

TONIGHT/FRIDAY AND AVIATION/MARINE...MRC
FRIDAY NIGHT THROUGH THURSDAY...ET