Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 011830 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1230 PM CST MON FEB 1 2016

.UPDATE...

AREA OF FOG/LOW CEILINGS WITH PATCHY DENSE FOG WAS SLOWLY MOVING
EASTWARD ACROSS THE SOUTHWEST PORTIONS OF THE AREA...THOUGH IT
APPEARS THAT IT IS SLOWING ITS EASTWARD MOVEMENT. THIS MAY BE DUE
TO DAYTIME HEATING. DENSE FOG HAS BEEN NOTED AT THE AIRPORTS IN
THIS AREA...BUT ARE LIKELY LOCALIZED WITH THE ROLLING TERRAIN.
WILL CONTINUE TO MENTION FOG WITH PATCHY DENSE IN THE FAR
SOUTHWEST THROUGH THE AFTERNOON...AND WILL WATCH TRENDS.
OTHERWISE...QUIET WEATHER IS EXPECTED TODAY.

FOR THE WINTER STORM TRENDS TUESDAY INTO WEDNESDAY...THE MODELS
SEEM TO BE LOCKING IN ON A SURFACE LOW TRACK THROUGH FAR SOUTHEAST
WISCONSIN TUESDAY NIGHT. THE GFS CONTINUES TO BE THE FURTHEST
NORTH WITH THE LOW...WITH THE NAM/CANADIAN A BIT FURTHER SOUTH.

IT APPEARS THAT THERE MAY BE MORE WARMTH IN THE SOUTHEAST
PORTIONS OF THE AREA...WITH THE BEST AXIS FOR HEAVY SNOW FROM
SOUTHWEST TO NORTHEAST WISCONSIN. THIS KEEPS THE FAR NORTHWEST
COUNTIES IN THE BEST SPOT FOR HEAVY SNOWFALL...WITH THE MIX AND
RAIN AREAS POSSIBLY SHIFTING FURTHER TO THE NORTHWEST.

IN ADDITION...DRIER AIR IN THE LOW LEVELS MAY DELAY THE ONSET OF
THE PRECIPITATION FOR SEVERAL HOURS IN THE AREA...ESPECIALLY THE
EAST. THUS...AMOUNTS AND TIMING MAY BE CHANGING TO A BIT LATER AND
THE HEAVY SNOW SHIFTING MORE TO THE NORTHWEST ACROSS THE AREA.
WILL CONTINUE TO EVALUATE TRENDS THIS AFTERNOON AND SEE IF ANY
CHANGES TO HEADLINES ARE NEEDED.

&&

.AVIATION/18Z TAFS/...

AREA OF LOW STRATUS AND FOG SHOULD REMAIN SOUTH AND WEST OF
MADISON FOR THE AFTERNOON HOURS. VFR CONDITIONS ARE THEN EXPECTED
THIS AFTERNOON AND MOST OF TONIGHT. THERE IS SOME UNCERTAINTY WITH
SOME 2 TO 5 MILE FOG DEVELOPMENT TONIGHT...AS WINDS REMAIN LIGHT
WITH LOW LEVEL MOISTURE LINGERING. LEFT IT OUT OF TAFS FOR NOW BUT
POSSIBILITY IS THERE FOR IT TO OCCUR. MIDDLE TO HIGH CLOUDS SHOULD
SPREAD IN TONIGHT AND GRADUALLY LOWER.

SOME UNCERTAINTY WITH THE TIMING OF THE PRECIPITATION WITH THE
WINTER STORM INTO TAF SITES ON TUESDAY. DRY AIR IN THE LOW LEVELS
MAY DELAY THE ONSET OF SNOW AT MADISON TUESDAY MORNING FOR SEVERAL
HOURS...AS WELL AS THE EASTERN SITES WITH A MIX OF RAIN AND SNOW.
18Z TAFS LIKELY HAVE TIMING TOO FAST INTO THE AREA...AND MAY BE
DELAYED UNTIL MIDDLE TO LATE MORNING TUESDAY...ESPECIALLY AT THE
EASTERN SITES.

AS FOR PRECIPITATION TYPES AND AMOUNTS...MADISON SHOULD SEE MAINLY
MODERATE TO SOMETIMES HEAVY SNOW LATER TUESDAY MORNING INTO LATE
AFTERNOON. THERE MAY BE SOME SLEET THAT MIXES IN AT TIMES IN THE
AFTERNOON. AMOUNTS LOOK TO REACH 5 TO 7 INCHES FOR TUESDAY...WHEN
THE HEAVIEST SNOWFALL IS ANTICIPATED. HOURLY RATES OF 1/2 TO 1
INCH PER HOUR ARE ANTICIPATED.

MADISON WINDS WILL BE EASTERLY IN THE 10 TO 20 KNOT RANGE...GUSTS
TO 25 KNOTS. THERE MAY BE ANOTHER INCH TUESDAY NIGHT...AS THE SNOW
BECOMES LIGHTER. WINDS WILL VEER TO THE NORTH AND THEN NORTHWEST
BY WEDNESDAY. MORE LIGHT ACCUMULATIONS AROUND AN INCH ARE POSSIBLE
WEDNESDAY...WITH SOME BLOWING SNOW POSSIBLE.

THE EASTERN SITES...ESPECIALLY MILWAUKEE AND KENOSHA...MAY NOT SEE
MUCH SNOW AT ALL GIVEN THE LATEST TRENDS IN THE COMPUTER MODELS.
THERE MAY BE A BRIEF PERIOD OF LIGHT SNOW LATER IN THE
MORNING...BUT IT SHOULD MIX WITH AND THEN CHANGE TO ALL RAIN BY
EARLY TO MIDDLE AFTERNOON. THE RAIN SHOULD LINGER TUESDAY
NIGHT...BEFORE SOME LIGHT SNOW OCCURS WEDNESDAY. GUSTY EAST WINDS
TUESDAY WILL VEER NORTH TO NORTHWEST TUESDAY NIGHT INTO WEDNESDAY.

&&

.MARINE...

GALE WATCH REMAINS IN EFFECT FROM 12Z TUESDAY TO 00Z WEDNESDAY
ACROSS THE NEARSHORE WATERS OF LAKE MICHIGAN. THE STRONG LOW
PRESSURE SYSTEM MOVING NORTHEASTWARD THROUGH THE REGION TUESDAY
INTO TUESDAY EVENING WILL BRING GUSTY ONSHORE WINDS AND HIGH
WAVES. SOME OF THESE WINDS WILL APPROACH GALE FORCE AROUND 35
KNOTS. WILL CONSIDER A GALE WARNING FOR THIS PERIOD WITH AFTERNOON
FORECAST.

THE GUSTY WINDS WILL SHIFT OFFSHORE LATER TUESDAY NIGHT INTO
WEDNESDAY NIGHT...AS THE LOW MOVES NORTHEAST AND AWAY FROM THE
AREA. GUSTS OF 25 TO 30 KNOTS ARE POSSIBLE DURING THIS TIME...WITH
HIGH WAVES SHIFTING TOWARD AND OVER THE OPEN WATERS. A SMALL CRAFT
ADVISORY WILL BE NEEDED FOR MOST OF THIS PERIOD.

&&

.PREV DISCUSSION... /ISSUED 342 AM CST MON FEB 1 2016/

SHORT TERM...

TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM.

THE UPPER FLOW BECOMES MORE WEST SOUTHWEST AS THE UPPER TROUGH OVER
THE ROCKIES PUSHES SLOWLY EAST.  UPPER LEVEL DIVERGENCE INCREASES
AFTER MIDNIGHT ALONG WITH 700 MB UPWARD MOTION.  700 MB UPWARD
MOTION BECOMES QUITE STRONG OVER THE ILLINOIS BORDER AREA OF
SOUTH CENTRAL WISCONSIN TOWARD SUNRISE.

700 MB RH DRIES TODAY...BUT THEN QUICKLY SATURATES LATE TONIGHT.  A
50 KNOT 700 MB JET MOVES INTO THE FAR SOUTH LATE TONIGHT.  THE
RESULTING MOISTURE CONVERGENCE SHOULD SPREAD SNOW INTO THE FAR
SOUTH.  AS SUCH WILL HAVE TO START THE WINTER HEADLINES A LITTLE
QUICKER IN THE FAR SOUTHWEST.

THE MAIN FORECAST PROBLEM THIS MORNING WILL BE FOG/STRATUS
CONCERNS...ESPECIALLY SOUTH CENTRAL AND HOW QUICK THE STRATUS
DISSIPATES.

TUESDAY AND TUESDAY NIGHT... FORECAST CONFIDENCE MEDIUM.

THE 00Z RUNS OF THE GFS AND ECMWF FINALLY CAME INTO AGREEMENT WITH
THE TRACK OF THE SURFACE LOW. THE NAM IS THE OUTLIER. THEY TAKE IT
FROM THE KS/NE/MO BORDER AT 18Z TUE TO THE MO/IA/IL BORDER AT 00Z
WED... AND TO CENTRAL LAKE MICHIGAN AT 06Z WED. THE TRACK OF THE
700MB LOW IS JUST TO THE NW OF THE SFC LOW AND SLIDES ACROSS CENTRAL
IOWA TUE AFTERNOON AND DIAGONALLY THROUGH CENTRAL WI TUE EVENING.
THE 850MB LOW IS RIGHT IN BETWEEN. THE AXIS OF HEAVIEST SNOW WILL BE
ALONG THE 700MB LOW TRACK AND COINCIDENT BAROCLINIC ZONE.

A E-W ORIENTED BAND OF STRONG 700MB FRONTOGENESIS WILL SLIDE
NORTHWARD ACROSS SOUTHERN WI TUE MORNING FROM 09Z TO 18Z. THERMAL
PROFILES SUGGEST ALL SNOW WITH THIS INITIAL BAND... EVEN IN SOUTHEAST
WI. THERE IS A LITTLE DRY AIR TO OVERCOME DURING THE ONSET OF THE
SNOW... BUT IT IS CHARACTERISTIC FOR STRONG FGEN TO WIN IN THESE
SITUATIONS. SNOWFALL RATES COULD BE QUITE HIGH WITHIN THIS BAND DUE
TO THE VERY STRONG UPWARD MOTION WITHIN THE DENDRITE GROWTH ZONE
/DGZ/ THAT COULD BE FAIRLY DEEP FOR A SHORT PERIOD OF TIME. DEBATED
ABOUT INCLUDING THE SOUTHEAST COUNTIES IN THE ADVISORY TO ACCOUNT
FOR THIS BAND. GIVEN TOTAL SNOWFALL AMOUNTS OPTED TO KEEP THEM OUT
FOR NOW... BUT CAUTION IS ADVISED DUE TO IMPACTS ON TUESDAY MORNING
COMMUTE.

THE DRY SLOT WILL MAKE ITS WAY INTO SOUTH CENTRAL WI AROUND 21Z TUE
AND INTO SOUTHEAST/ EAST CENTRAL WI BY 00Z WED. THIS IS GOING TO
DIMINISH THE PRECIP QUITE A BIT. THE ONLY EXCEPTION IS TOWARD
CENTRAL WI NEAR THE CENTER OF THE 700MB LOW. THAT 700MB FGEN BAND
WILL PIVOT OVER CENTRAL WI AND KEEP THE SNOW GOING THROUGH THE DAY
AND INTO THE EVENING. SO OUR MAIN EVENT FOR ALL BUT THE FAR W/NW
COUNTIES IN THE MKX COUNTY WARNING AREA /CWA/ WILL OCCUR DURING THE
DAYLIGHT HOURS FRIDAY.

THIS BRINGS US TO SURFACE TEMPERATURES. I UNDERCUT BLENDED GUIDANCE
FOR TEMPS TO ACCOUNT FOR DYNAMIC COOLING... ESPECIALLY TUE MORNING
AND IN THE WESTERN CWA TUESDAY AFTERNOON. THE GFS IS SHOWING WARM
AIR ALOFT BETWEEN 750 AND 850MB AND A COLD LAYER BENEATH THAT MIDDAY
TUESDAY. THIS WOULD MEAN A DECENT POTENTIAL FOR SLEET ALL THE WAY
INLAND TO MADISON. BY 00Z AFTER THE DRY SLOT GETS IN... TEMPERATURES
BELOW 5000 FT WARM ABOVE FREEZING... INCLUDING MADISON.  THIS MEANS
MUCH OF OUR AREA WILL HAVE RAIN/DRIZZLE EARLY TUE EVENING UNTIL THE
DEFORMATION ZONE CAN SLIDE ACROSS AND SATURATE UP TO THE DGZ TO
BRING SNOW SHOWER CHANCES THROUGH THE REST OF THE NIGHT.

UPGRADED THE WINTER STORM WATCH TO A WARNING AND ADDED SHEBOYGAN
COUNTY TO THAT. MADISON CITY AMOUNTS ARE STILL UNCERTAIN DUE TO THE
WARM AIR WRAPPING INTO SOUTH CENTRAL WI... BUT NORTHWEST OF THERE I
HAVE HIGHER CONFIDENCE IN MEETING WARNING CRITERIA.

LONG TERM...

WEDNESDAY... FORECAST CONFIDENCE MEDIUM.

MOISTURE WILL BE SHALLOW IN THE WAKE OF THIS SYSTEM... ALTHOUGH
ECMWF IS SHOWING JUST A LITTLE MORE QPF THAN GFS ON WED.
TEMPERATURES ALOFT WILL BE COOLING AND WHAT SHALLOW MOISTURE IS LEFT
COULD REACH THE DGZ SO KEPT CHANCE FOR SNOW SHOWERS ACROSS SOUTHERN
WI THROUGH THE DAY. BY WED NIGHT... WEAK SFC RIDGE MOVES IN AND
LIMITS SNOW POTENTIAL. CLEAR SKIES AND LIGHT WINDS SHOULD ALLOW
TEMPS TO DROP INTO THE SINGLE DIGITS AND LOWER TEENS.

THURSDAY AND FRIDAY... FORECAST CONFIDENCE MEDIUM.

FORECAST IS DRY FOR THU IS DRY ALTHOUGH A WEAK TROUGH MOVING THROUGH
COULD BRING MORE CLOUDS. FRIDAY NIGHT IS OUR NEXT TIME FOR LIGHT
SNOW CHANCES WITH POTENT UPPER TROUGH.

SATURDAY THROUGH MONDAY... FORECAST CONFIDENCE MEDIUM.

LIGHT SNOW CHANCES COULD LINGER ALONG A COLD FRONT DRAPED ACROSS
CENTRAL WI. HOWEVER THE ECMWF SUGGESTS A DRIER AND WARMER SOLUTION.

AVIATION/12Z TAFS/...

MVFR/IFR CIGS/VSBYS ALONG WITH SOME LIFR WILL BECOME MORE WIDESPREAD
THIS MORNING...ESPECIALLY OVER SOUTH CENTRAL WISCONSIN.  MUCH OF ANY
STRATUS IS EXPECTED TO SLOWLY LIFT DURING THE AFTERNOON AND EVENING.

THEN EXPECT IFR CIGS/VSBYS TO SPREAD INTO THE SOUTH...ESPECIALLY OVER
SOUTH CENTRAL WISCONSIN LATE TONIGHT AND TOWARDS SUNRISE AS A 50
KNOT 700 MB LOW LEVEL JET PUSHES NORTH AHEAD OF THE APPROACHING LOW
OVER EASTERN KANSAS.

MARINE...

GUSTY ONSHORE WINDS ARE EXPECTED TUESDAY INTO TUESDAY EVENING...AS A
STRONG LOW PRESSURE SYSTEM EXITS EASTERN KANSAS AND MOVES TOWARD
NORTHERN ILLINOIS AND FAR SOUTHEAST WISCONSIN.

THE STRONG WINDS WILL BECOME NORTHWEST LATER TUESDAY NIGHT INTO
WEDNESDAY...AS THE LOW MOVES NORTHEAST AWAY FROM THE AREA.

A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED FOR TUESDAY INTO
WEDNESDAY OR WEDNESDAY NIGHT IN LATER FORECASTS. GALE FORCE GUSTS
MAY OCCUR AT TIMES ON TUESDAY AND LATE TUESDAY NIGHT AS WELL. FOR
NOW WILL GO WITH A GALE WATCH FOR THE EAST WINDS AHEAD OF THE STRONG
LOW.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY FROM 6 AM TO 6 PM CST TUESDAY FOR WIZ059-
     060-064-065-068-069.

     WINTER STORM WARNING FROM 6 AM TUESDAY TO 6 AM CST WEDNESDAY FOR
     WIZ046-047-051-052-056>058-062-063.

     WINTER STORM WARNING FROM 4 AM TUESDAY TO 3 AM CST WEDNESDAY FOR
     WIZ067.

LM...GALE WATCH FROM TUESDAY MORNING THROUGH TUESDAY AFTERNOON FOR
     LMZ643>646.

&&

$$

UPDATE...WOOD
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
TUESDAY THROUGH SUNDAY...MRC


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