Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 210812
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
312 AM CDT THU MAY 21 2015

.TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH.

MOST PLACES SHOULD START OUT SUNNY THIS MORNING AS CLOUDS EXIT
THE FAR SOUTHEAST. TEMPS WILL REBOUND INTO THE UPPER 60S TO AROUND
70 THIS AFTERNOON...AS A WARMER AIR MASS PUSHES IN AHEAD OF AN
APPROACHING TROF/COLD FRONT DROPPING IN FROM THE NORTH FOR LATE
THIS AFTERNOON AND EVENING.

THE TROF...OR BACK DOOR COLD FRONT...WILL BE TIMED DURING MAX
DIABATIC HEATING...COUPLED WITH FAIRLY COLD TEMPS ALOFT. NEARLY
ALL THE MODELS DEVELOP SOME SHOWERS...MAYBE EVEN A RUMBLE OF
THUNDER...OVER THE FOX VALLEY OF EAST CENTRAL WISCONSIN VERY LATE
THIS AFTERNOON AND DRIFT IT SOUTH ACROSS THE EASTERN HALF OF THE
FORECAST AREA THIS EVENING.

THE FRONT WILL ACCELERATE DOWN THE LAKE SHORE WHILE THE SHOWERS
GRADUALLY DIMINISH WITH THE LOSS OF HEATING. WILL EXPAND THE POPS
A BIT GIVEN THE CONSENSUS. ALSO EXPECT A COUPLE OF HOURS OF GUSTY
NORTHEAST WINDS NEAR THE LAKE SHORE AFTER THE FRONT HITS. THINGS
WILL THEN CALM DOWN VERY QUICKLY THEREAFTER.

.SHORT TERM...FRIDAY THROUGH SATURDAY NIGHT...FORECAST CONFIDENCE
IS MEDIUM.

MODELS ARE IN GOOD AGREEMENT WITH HIGH PRESSURE SLIDING SOUTHEAST
ACROSS THE WESTERN GREAT LAKES REGION FRIDAY AND FRIDAY NIGHT. THE
HIGH WILL BRING QUIET WEATHER. COOL TEMPERATURES IN THE 50S TO
AROUND 60 ARE EXPECTED NEAR LAKE MICHIGAN FRIDAY...WITH ONSHORE
WINDS. MILDER MID TO UPPER 60S ARE EXPECTED WELL INLAND. LOWS
SHOULD FALL INTO THE 40S FRIDAY NIGHT...WITH LIGHT SOUTH WINDS.

MODELS CONTINUE TO SHOW DIFFERENCES WITH PRECIPITATION TRENDS
SATURDAY AND SATURDAY NIGHT. THE GFS TAKES THE 850 MB JET AND
POINTS IT INTO THE REGION LATER SATURDAY INTO SATURDAY NIGHT. THE
NAM/CANADIAN/ECMWF ALL KEEP THIS FEATURE WEST OF THE AREA DURING
THIS TIME. THE MODELS DO SLIDE A MODEST 500 MB VORTICITY MAXIMUM
EAST NORTHEAST THROUGH THE AREA SATURDAY AFTERNOON...WITH THE
BUILDING 500 MB RIDGE TO THE WEST OF THE REGION. STEADY WARM AIR
ADVECTION DEVELOPS OVER THE REGION SATURDAY INTO SATURDAY
NIGHT...WHICH BRINGS MORE MOISTURE AS WELL.

AREA FORECAST SOUNDINGS RESPOND WITH DEEPER MOISTURE PROFILES
SATURDAY NIGHT...THOUGH LITTLE ELEVATED CAPE EXISTS. FOR
NOW...WILL LEAVE IN LOW POPS IN THE FAR WEST SATURDAY
AFTERNOON...THEN SPREAD THEM INTO THE REST OF THE AREA SATURDAY
NIGHT. COULD SEE THIS PERIOD ENDING UP DRY...IF NAM/ECMWF/CANADIAN
MODELS VERIFY OVER THE AGGRESSIVE GFS.

.LONG TERM...SUNDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE IS
MEDIUM.

GFS/ECMWF CONTINUE TO DIFFER WITH TIMING OF PRECIPITATION SUNDAY.
THE GFS CONTINUES TO BE MORE AGGRESSIVE AND HAS QPF OVER THE AREA
WITH WARM AIR/MOISTURE ADVECTION CONTINUING. THE ECMWF PUSHES THE
FOCUSED WARM AIR ADVECTION INTO THE AREA SUNDAY AFTERNOON. AS
DISCUSSED EARLIER...THE ECMWF MAY BE MORE REALISTIC WITH ITS
SLOWER TIMING INTO THE AREA THAN THE AGGRESSIVE GFS. CONTINUED TO
USE CONSENSUS MODEL POPS FOR NOW ON SUNDAY...HIGHEST IN THE
SOUTHWEST COUNTIES.

THE GFS THEN KEEPS THE WARM FRONT WELL NORTH OF THE AREA SUNDAY
NIGHT INTO MONDAY...WITH THE ECMWF KEEPING IT OVER OR NEAR THE
AREA. BOTH MODELS DO SHOW SOUTHWEST FLOW AT 500 MB...WITH SEVERAL
VORTICITY MAXIMA PUSHING THROUGH. GFS VERY AGGRESSIVE WITH MEAN
LAYER CAPE/DEEP LAYER SHEAR MONDAY INTO MONDAY NIGHT...WHICH IS
PROBABLY OVERDONE. WILL CONTINUE WITH THE CONSENSUS MODEL POPS FOR
THIS PERIOD...AND KEEP THUNDER MENTION GOING. IF THE PRECIPITATION
OCCURS AS THE MODELS ARE SHOWING...WE SHOULD GET SOME BENEFICIAL
RAINFALL OVER THE AREA.

SOUTHWEST FLOW AT 500 MB LINGERS INTO THE MIDDLE OF THE WEEK ON
THE GFS/ECMWF...WITH SOUTH WINDS AT THE SURFACE HELPING KEEP WARM
AND MOIST CONDITIONS OVER THE AREA. WILL CONTINUE CONSENSUS POPS
FOR THIS PERIOD...AND KEPT THUNDER WORDING IN THIS PERIOD AS
WELL. MORE BENEFICIAL RAINFALL MAY OCCUR DURING THIS TIME.

&&

.AVIATION/12Z TAFS/...

VFR CONDITIONS EXPECTED DURING THE TAF PERIOD. THE MAIN
OPERATIONAL CONCERN IS LIKELY THE COLD FRONT THAT WILL BE TRACKING
SOUTH ACROSS THE AREA THIS EVENING. IT WILL BE ACCOMPANIED BY A
COUPLE HOUR PERIOD OF GUSTY NORTHEAST WINDS IN THE WAKE OF THE
FRONT FOR KMKE AND TO A WEAKER EXTENT AT KUES/KENW. A FEW SHOWERS
ARE ALSO POSSIBLE.

WINDS WILL SHIFT FROM WESTERLY TO NORTHEAST VERY ABRUPTLY AS THE
FRONT MOVES THROUGH. SOMETIMES THESE FRONTS WILL HAVE A BRIEF
PERIOD OF MVFR CIGS WITH THEM...BUT THEN CLEAR OUT VERY QUICKLY.
NOT SURE IF THAT WILL OCCUR IN THIS CASE. LOOK FOR THE WINDS TO
GUST TO AROUND 20KTS FOR AN HOUR OR SO...THEN SETTLE DOWN QUICKLY
THEREAFTER.

&&

.MARINE...A COLD FRONT WILL RACE DOWN THE LAKE EARLY THIS
EVENING...REACHING SHEBOYGAN AROUND 7 PM AND KENOSHA BY 9-10PM
THIS EVENING. WINDS WILL SHIFT ABRUPTLY FROM WESTERLY TO NORTHEAST
AND GUST TO AROUND 20KTS FOR A FEW HOURS BEFORE SETTLING BACK
DOWN.

&&

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

$$

TODAY/TONIGHT AND AVIATION/MARINE...DAVIS
FRIDAY THROUGH WEDNESDAY...WOOD


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