Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 250227 CCA
AFDMKX

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
927 PM CDT SUN APR 24 2016

.UPDATE...

18Z GFS AND 23Z HRRR EXPERIMENTAL AND 00Z NAM IS SHOWING A LITTLE
MORE OF A SEVERE WEATHER POTENTIAL FOR MONDAY AFTERNOON AND EARLY
EVENING.

18Z FORECAST SOUNDINGS INDICATE SOME SEVERE HAIL POTENTIAL AND
EVEN A MARGINAL TORNADO POTENTIAL. THE SEVERE WEATHER INDEX CWASP
RISES TO MID TO UPPER 70S. STP VALUES RISE TO AROUND 1 WITH THE
SUPERCELL INDEX AROUND 4. ZERO TO 1 KM MIXED LAYER CAPE RISES TO
AROUND 1400 JOULES/KG. THE GFS INDICATES SOUTHERN WISCONSIN WILL
BE IN THE WARM SECTOR... ALTHOUGH THE SURFACE BOUNDARY HAS BEEN
SAGGING SOUTH OVER THE NORTHEAST 2/3RDS OF THE FORECAST AREA. THIS
WILL BE THE MAIN CONCERN AS THE SURFACE LOW AND WARM FRONT MAY BE
FARTHER SOUTH THAN THE MODELS INDICATE...AS THE MODELS PUSH IT
BACK NORTH LATE TONIGHT AND MONDAY MORNING. MEANWHILE THE 850 MB
LOW TRACK IS ACROSS NORTHERN WISCONSIN...SO THE 850 MB WARM FRONT
WILL BE WELL TO THE NORTH.

IF THE GFS SURFACE TRACK IS CORRECT WITH THE LOW MOVING ACROSS
THE FOND DU LAC AND SHEBOYGAN AREA...THE SETUP WOULD FAVOR A
SEVERE WEATHER POTENTIAL OVER MUCH OF SOUTHERN WISCONSIN AS THE
700 MB SPEED MAX OF 50 KNOTS PUSHES ACROSS SOUTHERN WISCONSIN. THE
SOUTHWEST 850 MB WINDS INCREASE TO 35 KNOTS. MEANWHILE A 50 KNOT
WEST SPEED MAX PUSHES ACROSS BY EVENING WITH THE MAIN MID LEVEL
LOW OVER FAR NORTHERN WISCONSIN.

THE 18Z NAM HAS A MORE SOUTHERN TRACK OF THE SURFACE LOW...WITH
THE SEVERE THREAT THEN LIKELY LIMITED TO THE SOUTHWEST AND FAR
SOUTH.

THE STORM PREDICTION CENTER HAS MUCH OF SOUTHERN WISCONSIN IN A
MARGINAL RISK OF SEVERE THUNDERSTORMS. ANY UPGRADE TO SLIGHT RISK
WOULD LIKELY NEED MORE OF THE MODELS INDICATING THE NORTHERN
TRACK FOR THE SURFACE LOW. EVEN WITH THE HRRR EXPERIMENTALNORTHERLY
TRACK MUCH OF THE STRONG THUNDERSTORMS DEVELOP JUST SOUTH MORE
ACROSS NORTHERN ILLINOIS.

THE 00Z NAM IS STILL PUSHING THE BOUNDARY BACK NORTH MONDAY
MORNING WITH THE WARM FRONT APPRACHING THE DELLS TO JUST SOUTH OF
MILWAUKEE BY 1 PM. THE 00Z NAM ALSO SEEMS TO BE TRENDING TO MORE
OF THE 18Z GFS TRACK...SO STAY TUNED.

&&

.AVIATION/06Z TAFS/...

VFR CONDITIONS TO CONTINUE THIS EVENING AND OVERNIGHT ACROSS THE TAF
SITES. SOUTHWESTERLY WINDS OF 25 TO 35 KTS BETWEEN 1-2 KFT WILL
CREATE MARGINAL CONDITIONS FOR WIND SHEAR LATE THIS EVENING INTO THE
EARLY MORNING HOURS.

SHOWERS AND MAYBE A RUMBLE OF THUNDER ARE POSSIBLE LATE TONIGHT INTO
MONDAY MORNING AS AN UPPER AIR DISTURBANCE TRACKS THROUGH THE AREA.
VFR CIGS EXPECTED TO CONTINUE WITH THIS FEATURE.

A FRONT WILL STALL OVER CENTRAL WI DURING THE DAY MONDAY AND BE THE
FOCUS FOR POSSIBLE SHOWERS AND THUNDERSTORMS...WITH MVFR CONDITIONS
POSSIBLE AT TIMES. ANOTHER FRONT COULD BRING THUNDERSTORMS TO THE
REST OF SOUTHERN WI LATE MONDAY AFTERNOON/EVENING. SOUTH TO
SOUTHWESTERLY WINDS WILL GUST BETWEEN 15 TO 25 KTS LATE MONDAY
MORNING THROUGH THE AFTERNOON.

&&

.MARINE...

EASTERLY WINDS WILL VEER TO THE SOUTHEAST TO SOUTH ON MONDAY AHEAD
OF AN APPROACHING LOW PRESSURE SYSTEM.  ONCE THE LOW PASSES
BY...STRONGER NORTHEAST WINDS WILL PUSH DOWN THE LAKE LATE MONDAY
NIGHT INTO TUESDAY. THIS COULD RESULT IN SMALL CRAFT ADVISORY
CONDITIONS...ESPECIALLY NORTH OF MILWAUKEE. WINDS AND WAVES WILL
DECREASE BY TUESDAY NIGHT AS HIGH PRESSURE WITH AN EASTERLY FLOW
SETTLES ACROSS THE REGION.


&&

.PREV DISCUSSION... /ISSUED 307 PM CDT SUN APR 24 2016/

TONIGHT AND MONDAY... FORECAST CONFIDENCE MEDIUM.

MODELS ARE HAVING A HARD TIME RESOLVING THE SUBTLE FORCING FEATURES
JUTTING OUT AHEAD OF A CLOSED UPPER LOW THAT IS SLOWLY TRAVERSING
ACROSS THE PLAINS. CHANCES FOR LIGHT SHOWERS AND MAYBE A RUMBLE OF
THUNDER TOWARD CENTRAL WI INCLUDING FOND DU LAC AND SHEBOYGAN SHOULD
BE DIMINISHING EARLY THIS EVENING AS UPPER LEVEL RIDGING WORKS
FARTHER INTO SOUTHERN WI. THESE WERE ASSOCIATED WITH STEADY 850-
700MB WARM AIR ADVECTION AND FRONTOGENESIS.

LATER TONIGHT...SHORTWAVE ENERGY FROM THE APPROACHING UPPER LOW WILL
SWING FROM WEST TO EAST ACROSS SOUTHERN WI... PROBABLY BETWEEN 4 AM
AND 10 AM. THIS COULD BE ENOUGH FORCING FOR SOME SHOWERS. THERE WILL
BE SOME ELEVATED INSTABILITY PRESENT WITH THE STEEP UPPER LEVEL
LAPSE RATES AND EXTRA LIFT FROM THE LOW LEVEL JET... SO KEPT SMALL
MENTION OF THUNDER.

WE ARE STILL WAITING FOR THE SURFACE WARM FRONT TO CREEP INTO
SOUTHWEST WI AND BRING TEMPS UP A COUPLE MORE DEGREES INTO THE UPPER
70S LATE THIS AFTERNOON. THIS FRONT WILL CONTINUE TO BATTLE THE
COOLER AIR MASS INFLUENCED BY LAKE MICHIGAN... BUT MODELS AGREE ON
BRINGING IT NORTHWARD UP TO SOUTHERN FOND DU LAC AND SHEBOYGAN
COUNTIES BY LATE TONIGHT. THIS MEANS TEMPERATURES WILL BE WARMER
NEAR LAKE MICHIGAN ON MONDAY.

THIS FRONT WILL SIT OVER CENTRAL WI ON MONDAY AND BE THE FOCUS FOR
SHOWERS AND ISOLATED THUNDERSTORMS ONCE AGAIN. THE SURFACE LOW IS
EXPECTED TO MOVE INTO SOUTH CENTRAL WI SOMETIME ON MONDAY. LOW LEVEL
FRONTOGENESIS WILL SWEEP THROUGH THE AREA DURING THE LATE AFTERNOON.
SOME MODELS GENERATE CONVECTION ALONG THIS FRONT IN SOUTH
CENTRAL/SOUTHEAST WI WHILE OTHERS WAIT FOR IT TO CLEAR WI AND THEN
GENERATE PRECIP ALONG IT TO OUR SOUTHEAST DURING THE EVENING.

THE NAM CONTINUES TO BE ONE OF THE MORE ROBUST MODELS WITH
GENERATING HIGH CAPE UP TO 2000 J/KG WHILE THE GFS IS MORE MODERATE
AROUND 1000 J/KG. NONETHELESS THE SHEAR VALUES OF 30 TO 40 KNOTS
SUPPORT ORGANIZED CONVECTION. SPC KEPT SOUTHERN WI IN THE MARGINAL
RISK FOR SEVERE STORMS FOR THE ISOLATED POTENTIAL.

MONDAY NIGHT...FORECAST CONFIDENCE IS MEDIUM.

ANY ONGOING CONVECTION THAT FIRES LATE IN THE AFTERNOON ON MONDAY
WILL QUICKLY EXIT EAST DURING THE EVENING. THE COLD FRONT
ASSOCIATED WITH THE WEAKENING LOW WILL BE OVER THE SOUTHEAST RIGHT
AROUND 00Z TUESDAY...WITH A TRIPLE POINT ASSOCIATED WITH THE
WARM/OCCLUDED FRONT UP AROUND FOND DU LAC AND SHEBOYGAN. ALL THIS
SHOULD BE PUSHING INTO LOWER MICHIGAN BY 03Z TUESDAY. THERE IS A
VERY MARGINAL THREAT THAT SOME OF THESE STORMS COULD BE SEVERE
GIVEN THE POTENTIAL FOR FAVORABLE INSTABILITY AND DEEP LAYER SHEAR
ON THE ORDER OF 30-40KTS. HOWEVER...TOO MUCH CLOUDINESS MAY BE AN
ISSUE AND WILL LIMIT HOW UNSTABLE WE GET. AREAS WEST OF MADISON
WILL BE DRYING OUT BY THE START OF THIS PERIOD.

TUESDAY INTO TUESDAY NIGHT...FORECAST CONFIDENCE IS HIGH.

SFC HIGH PRESSURE WILL BUILD INTO THE AREA...BRINGING A MUCH
COOLER NORTHEAST THEN EASTERLY FLOW DURING THE PERIOD. COOLEST
READINGS OF COURSE WILL BE FELT ACROSS THE EASTERN HALF OF THE
FORECAST AREA DUE TO THE INFLUENCE OF THE COLD LAKE MICHIGAN
WATERS. BY LATE TUESDAY NIGHT...THE MID LEVEL RIDGE THAT BROUGHT
THE DRY CONDITIONS WILL PUSH EAST...ALLOWING THE ENERGY OF A
DECENT MID LEVEL CIRCULATION TO IMPINGE ON SOUTHWEST WISCONSIN. WE
COULD SEE SOME RAIN CHANCES ENTER THAT AREA AFTER ABOUT 4 AM.

WEDNESDAY THROUGH THURSDAY...FORECAST CONFIDENCE IS MEDIUM.

THAT MID LEVEL WAVE WILL BE VERY SLOW TO MOVE THROUGH THE
REGION DURING THIS PERIOD.  THE UPPER CIRCULATION WILL TRAVEL
FROM NEBRASKA WED MORNING TO NRN IL BY MID DAY ON THURSDAY. THE
ASSOCIATED SURFACE LOW WILL REMAIN SOUTH OF WISCONSIN...KEEPING US
ON THE CHILLY SIDE OF THINGS. RAIN WILL BEGIN SPREADING NORTH ON
WEDNESDAY BUT WILL BE HINDERED BY A VERY DRY EASTERLY FLOW. THIS
CLASSIC SET UP WILL LIKELY MEAN OUR NE FORECAST AREA WILL BE DRY
ON WED...BUT COLD DUE TO THE FLOW OFF THE LAKE. KEPT A SMALL
CHANCE OF RAIN UP THERE JUST IN CASE IT HAS MORE MOMENTUM THAN
EXPECTED. THE RAIN SHOULD EVENTUALLY OVERSPREAD ALL OF THE AREA
WEDNESDAY NIGHT INTO THURSDAY...BEFORE FINALLY ENDING THURSDAY
AFTERNOON. NO THUNDER. JUST A CHILLY RAIN.

THURSDAY NIGHT THROUGH FRIDAY NIGHT...FORECAST CONFIDENCE IS
MEDIUM.

HIGH PRESSURE SHOULD KEEP MUCH OF THE AREA DRY THROUGH THE PERIOD.
MUCH LIKE THE PREVIOUS SYSTEM...MID LEVEL RIDGING WILL BREAK DOWN
LATE FRIDAY NIGHT WITH ANOTHER CIRCULATION APPROACHING...BRINGING A
CHANCE OF RAIN TO THE AREA AFTER MIDNIGHT.

SATURDAY AND SUNDAY...FORECAST CONFIDENCE IS MEDIUM.

ANOTHER MID LEVEL CIRCULATION WILL DRIFT ACROSS THE AREA WITH THE
SURFACE LOW REMAINING TO OUR SOUTH. THIS BRINGS ANOTHER PERIOD OF
POTENTIAL RAIN FOR NEXT WEEKEND...AND GIVEN THE POSITION OF THE
SURFACE LOW...THE COOL EAST TO NORTHEAST WINDS WITH HIGHS IN THE
40S AND 50S WILL CONTINUE.

AVIATION/00Z TAFS/...

VFR CONDITIONS EXPECTED THROUGH THIS EVENING. CHANCE OF LIGHT
RAIN/SPRINKLES TODAY AND THIS EVENING TOWARD FOND DU LAC AND
SHEBOYGAN.

SOUTHWESTERLY WINDS OF 25 TO 35 KT BETWEEN 1000 AND 2000 FEET WILL
CREATE MARGINAL CONDITIONS FOR WIND SHEAR ONCE AGAIN LATE THIS
EVENING INTO THE EARLY MORNING HOURS.

SHOWERS AND MAYBE A RUMBLE OF THUNDER ARE POSSIBLE LATE TONIGHT INTO
MONDAY MORNING AS AN UPPER AIR DISTURBANCE TRACKS THROUGH THE AREA.
VFR CIGS EXPECTED WITH THIS FEATURE.

A FRONT WILL STALL OVER CENTRAL WI DURING THE DAY MONDAY AND BE THE
FOCUS FOR POSSIBLE SHOWERS AND THUNDERSTORMS AND MVFR CONDITIONS AT
TIMES. ANOTHER FRONT COULD BRING THUNDERSTORMS TO THE REST OF
SOUTHERN WI LATE MONDAY AFTERNOON/EVENING.

MARINE...

EASTERLY WINDS WILL VEER TO THE SOUTHEAST TO SOUTH ON MONDAY AHEAD
OF AN APPROACHING LOW PRESSURE SYSTEM.  ONCE THE LOW PASSES
BY...STRONGER NORTHEAST WINDS WILL PUSH DOWN THE LAKE LATE MONDAY
NIGHT INTO TUESDAY. THIS COULD RESULT IN SMALL CRAFT ADVISORY
CONDITIONS...ESPECIALLY NORTH OF MILWAUKEE. WINDS AND WAVES WILL
DECREASE BY TUESDAY NIGHT AS HIGH PRESSURE WITH AN EASTERLY FLOW
SETTLES ACROSS THE REGION.

&&

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

$$

UPDATE...HENTZ
TONIGHT/MONDAY AND AVIATION/MARINE...MRC
MONDAY NIGHT THROUGH SUNDAY...DAVIS



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