Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS63 KMKX 221656 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1156 AM CDT SUN MAR 22 2015

.UPDATE...

DEWPOINT TEMPS IN SOUTHERN WI BEGAN IN THE LOWER/MID 20S THIS
MORNING BUT HAVE BEEN DROPPING SEVERAL DEGREES OVER LAST COUPLE OF
HOURS AS DRY AIR ADVECTS INTO THE AREA ON NORTHEAST WINDS. RADAR HAS
BEEN SHOWING RETURNS OVER SOUTHERN WI ALL MORNING BUT THAT IS ALL
VIRGA... NOT HITTING THE GROUND... DUE TO THE DEEP LOW LEVEL DRY
LAYER.

AN AREA OF HIGHER REFLECTIVITY OVER SOUTHEAST MN AND NORTHEAST IOWA
IS TRACKING SOUTHEAST LATE THIS MORNING. IT SHOULD ARRIVE IN
SOUTHWEST WI AROUND 1 PM. THIS FEATURE IS ASSOCIATED WITH VORTICITY
ADVECTION AND STRONG MID LEVEL FRONTOGENESIS. IT IS REACHING THE
GROUND AS MAINLY SNOW WITH POCKETS OF SLEET UPSTREAM. THERE HAVE
BEEN REPORTS OF LIGHT ACCUMULATION ON THE GROUND ALREADY AND BRIEFLY
REDUCED VISIBILITY DOWN TO A HALF MILE AS WELL.

THE SHORT TERM MODELS CARRY THAT AREA OF HIGHER REFLECTIVITY ALL THE
WAY THROUGH SOUTH CENTRAL WI THIS AFTERNOON. THUS... RAISED POPS AND
HAVE SNOW/SLEET FOR THE WEATHER TYPE.

THERE SHOULD BE A LULL IN PRECIP LATE THIS AFTERNOON INTO THE EARLY
EVENING. THEN THE STRONGER VORTICITY ADVECTION WILL SPREAD INTO
SOUTHWEST WI ALONG WITH THE STRONG 850-700MB FRONTOGENESIS.

FOR TONIGHT... 12Z MODELS ARE COMING IN CONSISTENTLY SLOWER THAN THE
00Z RUNS AND YESTERDAY/S RUNS. THUS... THE BULK OF THE PRECIP WILL
FALL OVERNIGHT TONIGHT AND TAPER OFF MONDAY MORNING. I USED A BLEND
OF THE 12Z GFS AND 12Z CANADIAN FOR QPF AMOUNTS WITH THIS SYSTEM.
HIGHEST SNOWFALL AMOUNTS ARE EXPECTED IN THE 3 TO 5 INCH RANGE
ROUGHLY FROM THE DELLS TO VERONA TO JANESVILLE. WE PLAN TO ISSUE A
WINTER WEATHER ADVISORY FOR THE SOUTHWEST MKX COUNTIES FROM THIS
EVENING THROUGH MONDAY MORNING.

&&

.AVIATION/18Z TAFS/...

MID CLOUDS HAVE SPREAD ACROSS AREAS MAINLY NORTH OF MADISON TO
KENOSHA. DRY AIR FROM THE RETREATING HIGH PRESSURE OVER THE UPPER
GREAT LAKES MEANS MAINLY VFR CONDITIONS THROUGH MUCH OF TODAY EXCEPT
FOR AREAS OF MVFR CIGS OFF LAKE MICHIGAN.

AN AREA OF SNOW AND SLEET SHOWERS WILL SLIDE SOUTHEAST THROUGH
SOUTHWESTERN WI EARLY THIS AFTERNOON. SEE THE MAIN FORECAST
DISCUSSION FOR DETAILS.

THE HEAVIEST SNOW WILL BE STAYING MAINLY TO THE WEST AND SOUTH OF A
DELLS TO MADISON TO JANESVILLE LINE AND OCCUR LATE THIS EVENING
THROUGH 8 AM MONDAY MORNING. SEE THE LATEST SNOWFALL GRAPHICS ON OUR
WEBSITE. FREEZING DRIZZLE IS LOOKING LESS LIKELY FOR MONDAY MORNING
BUT CANNOT RULE IT OUT COMPLETELY.

&&

.PREV DISCUSSION... /ISSUED 300 AM CDT SUN MAR 22 2015/

TODAY AND TONIGHT...FORECAST CONFIDENCE MEDIUM.

THE RIGHT ENTRANCE REGION OF A 110 KNOT 250 MB UPPER JET MOVES
ACROSS SOUTHERN WISCONSIN LATER TODAY AND TONIGHT.  MAINLY WEAK
UPPER DIVERGENCE.  THE ASSOCIATED 500 MB SHORTWAVE AND CYCLONIC
VORTICITY ADVECTION IS RATER WEAK.  THE 850/700 MB BAROCLINIC ZONE
EXTENDS ACROSS SOUTHERN WISCONSIN WITH A WEAK 850 MB LOW MOVING EAST
INTO IOWA LATE TONIGHT.  850 MB TEMPERATURES ARE COLD ENOUGH FOR
SNOW.  MODERATE 700 MB UPWARD MOTION BEGINS THIS EVENING AND
CONTINUES TONIGHT.

WEAK UPWARD MOTION BEGINS BY THIS AFTERNOON OVER SOUTH CENTRAL
WISCONSIN...BUT DRY AIR IN LOW LEVELS WILL DELAY THE START OF
PRECIPITATION REACHING THE GROUND. MOISTURE SHOULD BE ENOUGH TO
OVERCOME THE DRY AIR AT THE GROUND AND BEGIN PRODUCING
PRECIPITATION MAINLY WEST OF MADISON THIS AFTERNOON. SURFACE
TEMPERATURES IN THE UPPER 30S TO LOWER 40S AT THIS TIME WOULD
SUGGEST RAIN...BUT GIVEN THE STRONG FORCING WITHIN THE DENDRIDIC
GROWTH ZONE...IT COULD STILL REACH THE GROUND WITH SOME SNOW MIX.

TIMING OF THE PRECIPITATION IS A LITTLE UNCERTAIN...AS IS THE NARROW
STRIPE OF MORE SIGNIFICANT PRECIPITATION.  SOME MODELS...ESPECIALLY
THE MESO MODELS ARE QUICKER TO BRING IT TO AREAS WEST AND SOUTH OF
MADISON THIS MORNING ALL THE WAY INTO SOUTHEAST WI BY 06Z....WHILE
THE GFS IS STILL DRY ACROSS SOUTHEAST WISCONSIN THROUGH MIDNIGHT.
ISENTROPIC ANALYSIS INDICATES THE MAIN PRECIPITATION WILL OCCUR LATE
TONIGHT. WILL USE THE CONSENSUS PRECIPITATION TOTALS.

GIVEN THE LATE ONSET AND MARGINAL SNOW AMOUNT TOTALS WITH THE
CONSENSUS QPF...WILL NOT ISSUE A WINTER WEATHER ADVISORY AT THIS
TIME.

THE HEAVIEST SNOW WILL BE STAYING MAINLY TO THE WEST AND SOUTH OF A
MADISON TO KENOSHA LINE.  THE MAJORITY OF THE SNOW WILL FALL LATE
TONIGHT. THERE COULD BE A PERIOD OF FREEZING DRIZZLE AS THE
PRECIPITATION COMES TO AN END EARLY MONDAY MORNING.

MONDAY - CONFIDENCE...MEDIUM
SHORTWAVE ACTIVITY ALONG WITH LINGERING ISENTROPIC ASCENT WILL
MAKE FOR ONGOING PRECIPITATION AT THE OUTSET. WITH THE GRADUAL
LOSS OF SATURATION WITHIN THE DENDRIDIC GROWTH ZONE WILL INCLUDE
MENTION OF PATCHY ZL- UNTIL PRECIP SHIELD EXITS TO THE SOUTH. M
PROGGD TO EXIT FAIRLY QUICK MONDAY MORNING SO WILL CONFINE POPS
TO JUST THE MORNING HOURS. LLVL RH PROGS SHOW LESS WESTWARD PUSH
OF CLEARING THAN LAST NIGHTS RUN. HOWEVER KSBM SOUNDINGS SHOW SOME
DRYING IN THE LOW LEVELS SO SOME CLEARING POSSIBLE IN THE NE CWA.

TUESDAY - CONFIDENCE...MEDIUM
MID LEVEL RIDGING PROGGD EARLY ON WITH PRIMARY VORT MAX IN THE
CENTRAL PLAINS. THE NAM SHOWS A MORE PRONOUNCED LEAD SHORTWAVE
RIDING THROUGH THE RIDGE AXIS WITH AN EARLIER ONSET TO PRECIP. THE
GFS AND ECMWF HOLD THIS OFF UNTIL MUCH LATER. PREFER CONSENSUS OF
THE LATTER WITH THEIR RESPECTIVE SOLUTIONS SHOWING WEAKER LESS
PRONOUNCED WAVES. ALSO THE GFS AND ECMWF KEEP LLJ/MOIST INFLUX
MORE TO THE WEST OF HERE THROUGH 00Z. WILL HAVE SMALL POPS IN
WESTERN CWA ESP IN THE AFTERNOON CLOSER TO LLJ AXIS.

TUESDAY NIGHT - CONFIDENCE...HIGH
MAIN SURGE STILL ON TRACK WITH LIKELIHOOD OF WIDESPREAD RAINFALL.
SHORTWAVE TAKES ON A NEGATIVE TILT AND LLJ AXIS ORIENTS QUITE
FAVORABLY INTO THE CWA TO SUPPORT A DECENT INFLUX OF MOISTURE.
BUFKIT SOUNDINGS NOT SUPPORTIVE OF ADDING THUNDER WITH LACK OF
DECENT LAPSE RATES/ELEVATED CAPE.

WEDNESDAY - CONFIDENCE...MEDIUM
SURFACE LOW AND UPPER WAVE WAVE PROGGD TO SHIFT NORTHEAST WITH
850 COLD ADVECTION GRADUALLY TAKING HOLD IN THE WAKE OF THESE
FEATURES. HOWEVER 925 TEMPS ARE NOT AS QUICK TO COOL WITHIN THE
STRONG WESTERLY FLOW SO WENT WITH THE SUPERBLEND TEMPS FOR NOW.
BEST WRAPAROUND PRECIP POTENTIAL WITH LINGERING LOW LEVEL TROUGH
AXIS IS ACROSS THE NORTHERN CWA AND MAINLY IN THE MORNING.

THURSDAY - CONFIDENCE...MEDIUM
MID LEVEL TROUGH AXIS PIVOTS SOUTHEAST INTO SRN WI WITH LOW LEVEL
COLD ADVECTION AND ARRIVAL OF SURFACE TROUGH. SO WILL HAVE SOME
POPS FOR THESE FEATURES. CHILLIER REGIME AS NORTHERLY FLOW TAPS
COLDER 925 TEMPS.

FRIDAY - CONFIDENCE...MEDIUM
MID LEVEL TROUGH AXIS MOVES SOUTHEAST OF SRN WI. SURFACE/850
HIGHS DRAW CLOSER. WILL STICK WITH THE DRY SUPERBLEND POPS FOR
NOW. HOWEVER GEM IS SLOWER AND A BIT STRONGER WITH THE MID LEVELS
SHOWING A CLOSED CIRCULATION ACROSS THE AREA DURING THE MORNING.
GFS/ECMWF MORE PROGRESSIVE.

SATURDAY - CONFIDENCE...MEDIUM
SURFACE HIGH OFF TO THE EAST WITH RETURN SOUTHERLY SETTING UP.
PRECIP ASSOCIATED WITH NEXT SYSTEM LIKELY TO ARRIVE SATURDAY
NIGHT. FAIRLY DECENT AGREEMENT FROM THE GFS/ECMWF THIS FAR OUT.

AVIATION/12Z TAFS/...MID CLOUDS HAVE SPREAD ACROSS AREAS MAINLY
NORTH OF MADISON TO KENOSHA. DRY AIR FROM THE RETREATING HIGH
PRESSURE OVER THE UPPER GREAT LAKES MEANS MAINLY VFR CONDITIONS
THROUGH MUCH OF TODAY EXCEPT FOR AREAS OF MVFR CIGS OFF LAKE
MICHIGAN. EVEN THE POTENTIAL START OF PRECIPITATION...BY 18Z
MAINLY WEST OF MADISON AT KMSN AND AFTER 00Z AT MILWAUKEE AND
KENOSHA...WILL SEE CLOUD BASES IN THE 3500 TO 5K FT RANGE INITIALLY
AND 6 MILE VSBYS BEFORE DIPPING TO IFR WITH THE STEADIER SNOW
TONIGHT.

THE HEAVIEST SNOW WILL BE STAYING MAINLY TO THE WEST AND SOUTH OF A
MADISON TO KENOSHA LINE.  SNOW AMOUNTS BY 12Z MONDAY LOOK TO TOTAL
AROUND 2 INCHES AT KMSN...1 INCH AT KUES...AND BETWEEN 3/4 INCH AND
1 INCH AT KMKE AND KENW. THE MAJORITY OF THE SNOW WILL FALL LATE
TONIGHT. THERE COULD BE A PERIOD OF FREEZING DRIZZLE AS THE
PRECIPITATION COMES TO AN END EARLY MONDAY MORNING.

MARINE...PERSISTENT EAST FLOW OF 10 TO 20 KNOTS WILL CAUSE WAVES
TO APPROACH SMALL CRAFT CRITERIA TODAY.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...WINTER WEATHER ADVISORY FROM 8 PM THIS EVENING TO 8 AM CDT
     MONDAY FOR WIZ056-062-063-067>069.

LM...NONE.
&&

$$

UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
MONDAY THROUGH SATURDAY...COLLAR


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.