Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 282206
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
406 PM CST FRI NOV 28 2014

.TONIGHT...FORECAST CONFIDENCE MEDIUM.

FREEZING RAIN AND SLEET DEVELOPED ACROSS SOUTHEAST MN EARLY THIS
AFTERNOON WITHIN A REGION OF 850-700MB FRONTOGENESIS... A WEAK 500MB
SHORTWAVE AND UPPER DIVERGENCE IN THE ENTRANCE REGION OF AN UPPER
JET STREAK. THAT AREA IS TRACKING SOUTHEAST AND IS CURRENTLY OVER LA
CROSSE AND SHOULD CONTINUE TO SPREAD SOUTHEAST INTO SOUTH CENTRAL
WI.

THE MIXED PRECIP TYPE IS DUE TO THE THERMAL PROFILE OF THE
ATMOSPHERE. TEMPERATURES ARE WARMING ALOFT THIS AFTERNOON. THE MAX
TEMP IS EXPECTED TO BE AROUND 800-850MB OF +4C AT MSN AT 00Z. THIS
IS ALSO A DRY LAYER WITH THE WAA ADVECTING DRIER AIR IN FROM THE
PLAINS. 500MB SHORTWAVE ENERGY AND UPPER DIVERGENCE IN THE ENTRANCE
REGION OF A JET STREAK WILL LEAD TO ENHANCED UPWARD MOTION WITHIN
THE DENDRITIC GROWTH ZONE... LOCATED AT 500-600MB LEVEL. IT IS
TAKING TIME TO SATURATE FROM THE TOP DOWN TO PRODUCE LIGHT PRECIP AT
THE GROUND. CEILINGS ARE QUITE HIGH UPSTREAM. THIS FORCING WILL ONLY
BE OVER SOUTHERN WI FOR A SHORT TIME PERIOD THIS EVENING...SO THAT
WILL LIMIT OUR AMOUNTS OF ANY ICE ACCUMULATION.

DIURNAL CU DEVELOPED THIS AFTERNOON IN THE SUNNY AREAS AND THIS AREA
IS TURNING INTO STRATUS AS IT GETS DARK AND IS ACTUALLY EXPANDING A
LITTLE IN AREAL COVERAGE. THE LOWER CEILINGS WITHIN THIS BAROCLINIC
ZONE/ DIURNAL CU ZONE ARE PAVING THE WAY FOR THIS FROZEN PRECIP LATE
THIS AFTERNOON INTO THE EARLY EVENING. I HAVE HIGH CONFIDENCE THAT
THE DELLS AREA WILL SEE A MIX OF FREEZING RAIN AND SLEET LATE THIS
AFTERNOON AND INCREASING CONFIDENCE THAT MADISON WILL BE IMPACTED AS
WELL.

EVEN VERY LIGHT ACCUMULATIONS OF ICE WILL HAVE IMPACTS ON TRAVEL. WE
WILL HANDLE THIS SITUATION WITH NOWCASTS AND SPECIAL WEATHER
STATEMENTS AS IT EVOLVES.

AFTER THE PRECIP ENDS WE WILL BEGIN WARMING AT THE SURFACE AS WARM
AIR ADVECTION IN THE LOW LEVELS TAKES HOLD. TEMPERATURES ARE
EXPECTED TO WARM INTO THE LOWER 30S BY EARLY MORNING AND INTO THE
MID TO UPPER 40S NEAR THE WI/IL BORDER BY SATURDAY AFTERNOON. THIS
BEGS THE QUESTION ABOUT HOW WIDESPREAD AND DENSE FOG WILL BECOME
WITH WARM AIR ADVECTING OVER OUR SNOW PACK AND ALSO WITH SOME
MELTING SNOW.

DEWPOINT TEMPS ARE NOT EXPECTED TO RISE ABOVE FREEZING UNTIL
SATURDAY AFTERNOON. THIS WILL KEEP OUR SNOW FROM RAPIDLY MELTING AND
HELP TO KEEP THE DENSE FOG AWAY. SOME MODELS... ESPECIALLY THE
NAM... ARE DEVELOPING DENSE FOG OVERNIGHT. THE NAM HAS BEEN
OVERDOING THE LOW LEVEL MOISTURE LATELY DUE TO ITS ASSUMPTION OF
DEEPER SNOW COVER THAN WHAT IS ACTUALLY THERE. IT IS ALSO ASSUMING
THAT WE WILL BE MELTING A LOT OF SNOW OVERNIGHT. AFTER COORDINATION
WITH THE SURROUNDING OFFICES... WE HAVE PATCHY TO AREAS OF FOG IN
THE FORECAST BUT NOT EXPECTING WIDESPREAD DENSE FOG.

.SHORT TERM...SATURDAY NIGHT THROUGH MONDAY NIGHT.

SATURDAY NIGHT...FORECAST CONFIDENCE HIGH.

A PAIR OF WEAK SHORT WAVES RIPPLE THROUGH IN FAST MOVING ZONAL FLOW
SATURDAY NIGHT...RIDING 140 KT 250 MB JET STREAK. SOME WEAK
VORTICITY ADVECTION/300-500MB Q-VECTOR CONVERGENCE IN THE EAST
BETWEEN 00Z AND 06Z SUNDAY...WITH SECONDARY 850 MB THERMAL RIDGE
NOSING INTO THE REGION AHEAD OF MID LEVEL TROUGH PRODUCING SOME
ISENTROPIC ADIABATIC OMEGA. SOME WEAK SURFACE MOISTURE CONVERGENCE
ALONG SURFACE TROUGH...BUT THIS LESSENS WITH TIME AS SURFACE LOW
LIFTS AWAY TO THE NORTHEAST.

HOWEVER DRY PLAINS AIR ADVECTING IN ON WSW WINDS KEEPING COLUMN DRY
ABOVE 900 MB ON FORECAST SOUNDINGS...AND CONDENSATION PRESSURE
DEFICITS AT OR ABOVE 100 MB INTO SUNDAY MORNING. COULD SEE SOME
PATCHY DRIZZLE BUT MOIST LAYER TOO SHALLOW TO PRODUCE MEASURABLE
PCPN. COULD ALSO SEE SOME PATCHY FOG...BUT LOW LEVEL SATURATION NOT
EXTENSIVE ENOUGH...AND COLLABORATION LEADS TO NOT MENTIONING AT THIS
TIME.

TEMPS ONLY COOL ABOUT 5 TO 7 DEGREES FROM DAYTIME HIGHS EARLY IN THE
EVENING THEN REMAIN STEADY UNTIL MIDNIGHT...COOLING AS COLD AIR
ADVECTION BEGINS BEHIND TROUGH THAT EXITS THE SE CORNER OF STATE
AROUND 12Z SUNDAY.

SUNDAY THROUGH MONDAY NIGHT...FORECAST CONFIDENCE HIGH

TEMPS REBOUND A FEW DEGREES WITH MIDDAY HIGHS SUNDAY...THEN FALL AS
COLD AIR ADVECTION DROPS 925 MB TEMPS ON NW WINDS WITH SPRAWLING
HIGH PRESSURE BUILDING IN...WHICH WILL DOMINATE THE WEATHER THROUGH
THE REST OF THIS PERIOD.

WILL SEE SINGLE DIGIT LOWS SUNDAY NIGHT...WITH APPARENT TEMPERATURES
IN THE SINGLE DIGITS BELOW BY SUNRISE MONDAY. MONDAY HIGHS WELL
BELOW NORMAL IN THE TEENS...WITH AROUND 20 ALONG THE LAKESHORE AND
NEAR THE IL BORDER. WIND CHILL VALUES ONLY GET TO THE SINGLE DIGITS
ABOVE ZERO.

CORE OF THE HIGH MOVES ACROSS WISCONSIN MONDAY NIGHT...WITH CLEAR
AND NEAR-CALM CONDITIONS DIPPING LOWS TO NEAR ZERO IN THE NW
CWA...AND SINGLE DIGITS INLAND. LIGHT EASTERLY WINDS WILL KEEP
LOCALES ALONG THE LAKE MICHIGAN SHORE BETWEEN 10F AND 15F ABOVE.


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

SOME BETTER AGREEMENT AMONG THE LONGER RANGE MODELS...THOUGH
DISCREPANCIES REMAIN. ECMWF AND GEM STILL DIGGING 500 MB TROUGH
DEEPER THAN GFS TUESDAY NIGHT AND WEDNESDAY...BUT ALL KEEP SURFACE
LOW AND ASSOCIATED PCPN WELL TO THE NORTH THROUGH WEDNESDAY
MORNING...THEN HOLD OFF DEVELOPING PRECIP ALONG TRAILING SURFACE
TROUGH UNTIL GULF MOISTURE WICKS UP BEHIND DEPARTING HIGH...WELL TO
THE EAST OF THE STATE. GFS IS NOW CLOSER TO THE ECMWF IN KEEPING A
WEAKER SRN STREAM WAVE MOVING THROUGH IN NEAR ZONAL FLOW THURSDAY
NIGHT AND FRIDAY...THOUGH IT IS FASTER AND FOCUSING PCPN ALL SOUTH
OF STATE. WILL KEEP LOW POPS IN FOR NOW AND AWAIT MORE CONSISTENT
SIGNAL FROM MODELS. TEMPERATURES WORK BACK TOWARD SEASONAL
NORMALS.

&&

.AVIATION/00Z TAFS/...

THERMAL PROFILES SUGGEST THAT ANY PRECIPITATION DURING THE LATE
AFTERNOON AND EVENING WOULD BE FREEZING RAIN OR SLEET.  THE LOW
CEILINGS OVER MSN ARE GRADUALLY EXPANDING ACROSS SOUTHEAST WI LATE
THIS AFTERNOON. THESE LOW CIGS WILL PAVE THE WAY FOR THIS LIGHT MIXY
PRECIP THROUGH EARLY EVENING.

SOUTHERLY WINDS AHEAD OF A COLD FRONT OVERNIGHT WILL PULL IN WARMER
AND SOMEWHAT MORE MOIST AIR OVER SNOWPACK. PROBABILITIES OF IFR
CEILINGS INCREASE...ESPECIALLY INTO MSN. NOT CONFIDENT THAT THE
REALLY LOW IFR CIGS THAT THE NAM AND HRRR SUGGEST WILL PAN OUT.
EXPECTING AREAS OF LIGHT FOG... PROBABLY NOT WIDESPREAD DENSE FOG.

&&

.MARINE...

SOUTHERLY WIND GUSTS AND WAVES ARE REACHING SMALL CRAFT ADVISORY
LATE THIS AFTERNOON AND WILL LIKELY PERSIST THROUGH SATURDAY
EVENING. THUS... ISSUED A SMALL CRAFT ADVISORY.

BRISK NORTHWEST WINDS SUNDAY EVENING AND MONDAY WILL ALSO APPROACH
SMALL CRAFT ADVISORY LEVELS IN THE WAKE OF A COLD FRONT.

BRISK SOUTH WINDS ON TUESDAY AND TUESDAY NIGHT WILL ALSO GENERATE
RATHER HIGH WAVES

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM CST SATURDAY FOR LMZ643>646.

&&

$$

TONIGHT/SATURDAY AND AVIATION/MARINE...MRC
SATURDAY NIGHT THROUGH FRIDAY...REM


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