Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 300237
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
937 PM CDT FRI MAY 29 2015

.UPDATE...

MID-LEVEL LAPSE RATES HAVE STEEPENED A BIT OVER EAST CENTRAL WI
THIS EVENING...BUT MUCH LESS STEEP OVER THE REST OF SRN WISCONSIN
LIMITING INSTABILITY FOR THUNDERSTORMS. STILL ONLY GETTING BRIEF
PULSE STORMS THAT DO NOT LAST LONG ENOUGH TO PRODUCE MUCH IF ANY
CLOUD TO GROUND LIGHTNING...AND ONLY A SHORT PERIOD OF IN-CLOUDLIGHTNING
WITH THE STRONGEST CELLS. HOWEVER WITH PRECIPITABLE WATER VALUES
OF 1.6 TO 1.7 INCHES...THE STRONGER CELLS ARE PRODUCING RAINFALL
RATES OF 3 TO 4 INCHES PER HOUR...WHICH CAN YIELD UP TO 1 INCH OF
RAINFALL OVER THE 15-20 MINUTES WHEN THEY DROP THEIR PRECIPITATION
CORES.

MOST OF THE FORECAST AREA WILL SEE SHOWERS AND A FEW THUNDERSTORMS
SPREAD ACROSS WITH THE SURFACE TROUGH/COLD FRONT OVERNIGHT TONIGHT
INTO SATURDAY MORNING. WITH THE CURRENT FRONT TIMING...EXPECT
24-HOUR HIGHS FOR SATURDAY TO BE JUST AFTER MIDNIGHT. TAKING INTO
ACCOUNT THE FASTER MOVEMENT DOWN THE LAKESHORE...THE DAYTIME
HIGHS FOR SATURDAY SHOULD BE AROUND 12Z...EXCEPT MAY BE A REBOUND
IN THE FAR WEST LATE IN THE AFTERNOON.

&&

.AVIATION/06Z TAFS/...

LOOK FOR VFR CONDITIONS TO CONTINUE UNTIL SCATTERED TO BROKEN
COVERAGE SHOWERS MOVE IN WITH THE SURFACE TROUGH/COLD
FRONT...REACHING KMSN BY 03Z...KUES AROUND 0530Z AND KMKE AND KENW
AROUND 06Z. WILL MAINLY SEE MVFR VSBYS UNTIL AROUND 09Z...THEN A
SHORT PERIOD OF MVFR CIGS RIGHT BEHIND THE FRONT FALLING TO IFR
LEVELS UNTIL MID-MORNING IN THE WESTERN CWA...BUT REMAINING BELOW
1K FT IN THE EAST WITH THE MOIST COOL ONSHORE FLOW UNTIL LATE
AFTERNOON.

&&

.MARINE...

NO CHANGES TO HEADLINES AT THIS TIME...BUT NEXT SHIFT WILL HAVE TO
ASSESS THE FULL 00Z DATA SET TO SEE IF THERE WILL BE A NEED FOR A
GALE WARNING. 01Z RAP FORECAST SOUNDINGS INDICATE ENOUGH MIXING TO
TAP 33 TO 39 KNOT WINDS AROUND 400 FT FROM THE LATE MORNING
THROUGH THE END OF THE MODEL RUN AT 19Z...WHICH ARE SIMILAR TO THE
18Z GFS WINDS AT THAT HEIGHT THOUGH STRONGER THAN THE 18Z NAM.

&&

.PREV DISCUSSION... /ISSUED 353 PM CDT FRI MAY 29 2015/

TONIGHT AND SATURDAY...FORECAST CONFIDENCE - HIGH.

ON AND OFF SHOWERS WITH A FEW STORMS WILL CONTINUE THIS AFTERNOON
AND OVERNIGHT. CURRENT ACTIVITY MAY WIND DOWN FOR A TIME LATER THIS
AFTERNOON...WITH MORE SHOWERS/STORMS MOVING IN FROM THE WEST IN THE
EVENING AND NIGHT HOURS AND A COLD FRONT DROPS SOUTHEAST INTO THE
AREA. THE COLD FRONT WILL MAKE IT DOWN TO ABOUT THE
MADISON/MILWAUKEE AREAS BY DAYBREAK SATURDAY...CROSSING THE WI/IL
BORDER EARLY MORNING. MORE SHOWERS AND MAYBE A COUPLE STORMS WILL
PERSIST THROUGH THE MORNING ON THE BACK SIDE OF THE SURFACE LOW AS
THE UPPER TROUGH MOVES THROUGH. MODELS HAVE SLOWED DOWN OVERALL...SO
RAISED POPS FOR TOMORROW. SHOULD SEE RAIN WIND DOWN NORTHWEST TO
SOUTHEAST LATE MORNING INTO THE AFTERNOON.

STILL A MARGINAL RISK FOR SEVERE STORMS PER SPC...THOUGH HAVE NOT
SEEN MUCH OF CONCERN SO FAR...AND INSTABILITY WILL GENERALLY
DECREASE THROUGH THE EVENING HOURS. SOMETHING TO KEEP AN EYE ON
THOUGH.

TEMPS WILL CRASH LATE TONIGHT INTO SATURDAY MORNING AS THE COLD
FRONT MOVES THROUGH...WITH A COOL SATURDAY IN STORE FOR SOUTHERN
WISCONSIN...ESPECIALLY NEAR LAKE MICHIGAN. LINGERING CLOUDY SKIES
AND BREEZY NORTH TO NORTHEAST WINDS WILL ADD A BIT MORE OF A CHILL
IN THE AIR AS WELL.

SATURDAY NIGHT THROUGH MONDAY...FORECAST CONFIDENCE - HIGH.

LOW TO MID-LEVEL Q-VECTOR CONVERGENCE EXITS SOUTHEAST WI EARLY
SATURDAY EVENING AS BREEZY NORTHEAST WINDS CONTINUE TO FEED DRIER
AIR ACROSS SOUTHERN WISCONSIN.  LINGERING EVENING CLOUDINESS SHOULD
CLEAR...SUCCUMBING TO DRY AIR ONSLAUGHT.  A COOL NIGHT IS EXPECTED
WITH 925H TEMPS FALLING TO 4-5C. WITH CLEAR SKIES...OVERNIGHT TEMPS
WILL FALL INTO THE UPPER 30S TO LOWER 40S MOST AREAS.  A FEW
SUSCEPTIBLE LOCATIONS WILL FALL INTO THE MIDDLE 30S.  HOWEVER DUE TO
LINGERING BOUNDARY LAYER MIXING...NOT EXPECTING ANY FROST FORMATION
LATE SATURDAY NIGHT.

COOL AIR REMAINS IN PLACE THROUGH SUNDAY INTO SUNDAY NIGHT BEFORE
WARMING TREND COMMENCES.  LIGHTER BOUNDARY LAYER WINDS AND CONTINUED
DRY ATMOSPHERE WILL ALLOW TEMPS TO FALL INTO THE MIDDLE 30S TO LOWER
40S SUNDAY NIGHT.  PENDING AMOUNT OF UPSTREAM HIGH CLOUD COVER THAT
WORKS INTO SOUTHERN WI...MAY BE SOME PATCHY LATE NIGHT FROST IN
SUSCEPTIBLE AREAS SUNDAY NIGHT.

MONDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE - MEDIUM.

NO SURPRISES FROM 24 HOURS AGO. CENTRAL CONUS LARGE-SCALE RIDGING
EXPANDS INTO UPPER MIDWEST EARLY IN THE PERIOD RESULTING IN WARMING
TREND AND QUIET CONDITIONS THROUGH TUE.  SOME CONCERN ABOUT
POTENTIAL SHORT WAVE MOVING EWD ACROSS CONUS/CANADIAN BORDER TUE
NIGHT AND WED. INCREASING SOUTHERLY WINDS WILL ALLOW COLUMN PWAT TO
INCREASE TO OVER 0.50 INCH. MEDIUM RANGE GUIDANCE DIVERGES ON
STRENGTH AND PLACEMENT OF THIS WAVE...WITH MORE CONSISTENT ECMWF
MUCH WEAKER THAN GFS AND GEM.  MEDIUM RANGE GUIDANCE IN BETTER
AGREEMENT ON LARGE SCALE RIDGE RE-EXPANDING INTO THE UPPER MIDWEST
AROUND THURSDAY.  STRONGER MID-LEVEL SHORT WAVE LOOKS TO FLATTEN
RIDGING ACROSS THE UPPER MIDWEST THU NIGHT AND FRI. HENCE THIS
PERIOD LOOKS TO HAVE BEST CHANCE FOR MORE WIDESPREAD CONVECTION.
DAYTIME TEMPERATURES WILL REMAIN ON THE WARM SIDE FOR MUCH OF THE
EXTENDED PERIOD.  HOWEVER LAKESHORE AREAS WILL REMAIN COOLER DUE TO
A PROLONGED PERIOD OF S TO SE WINDS.

GFS 5-DAY 500H MEANS CONTINUE TO SHOW WEST TO SOUTHWEST STEERING
FLOW THROUGH THE FIRST WEEK OF JUNE AND ABOVE NORMAL HEIGHTS.  HENCE
EXPECT WARMER THAN NORMAL TEMPS FOR MUCH OF THE PERIOD WITH GOOD
GROWING CONDITIONS AND LITTLE FROST THREAT.

AVIATION/00Z TAFS/...

CURRENT SHOWERS/STORMS MAY WIND DOWN FOR A TIME LATER THIS
AFTERNOON...WITH MORE CONVECTION MOVING IN FROM THE WEST IN THE
EVENING AND NIGHT HOURS AND A COLD FRONT DROPS SOUTHEAST INTO THE
AREA. THE COLD FRONT WILL MAKE IT DOWN TO ABOUT THE
MADISON/MILWAUKEE AREAS BY DAYBREAK SATURDAY...CROSSING THE WI/IL
BORDER EARLY MORNING. EXPECT A FAIRLY QUICK SHIFT AND INCREASE IN
THE WINDS AS THE FRONT MOVES THROUGH.

MORE SHOWERS AND MAYBE A COUPLE STORMS WILL PERSIST THROUGH THE
MORNING ON THE BACK SIDE OF THE SURFACE LOW AS THE UPPER TROUGH
MOVES THROUGH.

OUTSIDE OF MODERATE TO HEAVY RAINFALL...VFR CONDITIONS WILL LIKELY
PERSIST INTO THIS EVENING. EXPECT LOWER CIGS TO MOVE IN OVERNIGHT AS
THE COLD FRONT MOVES THROUGH. SHOULD SEE RAIN WIND DOWN NORTHWEST TO
SOUTHEAST LATE MORNING INTO THE AFTERNOON...WITH SLOWLY IMPROVING
CIGS AS DRIER AIR WORKS INTO THE AREA.

MARINE...

NORTH TO NORTHEAST WINDS WILL BECOME GUSTY SATURDAY MORNING BEHIND A
DEPARTING COLD FRONT. GUSTS TO 30 KNOTS ARE EXPECTED ON SATURDAY.
WINDS WILL EASE A BIT SATURDAY NIGHT AND SUNDAY...BUT THE PRESSURE
GRADIENT LOOKS TO BE TIGHT ENOUGH TO KEEP GUSTS TO 25 KNOTS GOING
THROUGH THE DAY SUNDAY. A SMALL CRAFT ADVISORY IS THUS BEING ISSUED
THIS AFTERNOON FOR SATURDAY THROUGH THE DAY SUNDAY.

MAY SEEM SOME FOG AT TIMES THIS EVENING INTO TONIGHT GIVEN THE MOIST
AIRMASS OVER THE COOLER WATERS. SO FAR THOUGH...THE NEARSHORE AREAS
SEEM TO BE REMAINING MAINLY FREE OF FOG. SOMETHING TO KEEP AN EYE ON
UNTIL THE COLD FRONT MOVES THROUGH LATE TONIGHT INTO SATURDAY
MORNING.

BEACHES...

HIGH SWIM RISK CONDITIONS ARE EXPECTED ON SATURDAY. STRONG NORTH TO
NORTHEAST WINDS WILL BRING LIFE THREATENING WAVES AND CURRENTS ALONG
THE LAKE MICHIGAN SHORE. A HAZARD IS NOT BEING ISSUED TO DUE COLD
AIR TEMPERATURES...BUT FOR THOSE THAT VENTURE OUT...IT IS ADVISED TO
STAY OUT OF THE WATER SATURDAY AND SATURDAY NIGHT.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY FROM 7 AM SATURDAY TO 7 PM CDT SUNDAY FOR
     LMZ643>646.

&&

$$

UPDATE...REM
TONIGHT/SATURDAY AND AVIATION/MARINE...DDV
SATURDAY NIGHT THROUGH FRIDAY...MBK



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