Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 252037
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
337 PM CDT MON MAY 25 2015

.TONIGHT AND TUESDAY...FORECAST CONFIDENCE IS MEDIUM.

A FEW SHOWERS ARE STILL DEVELOPING AND DISSIPATING ACROSS PORTIONS
OF THE AREA THIS AFTERNOON...AS 500 MB VORTICITY MAXIMUM PASSES
THROUGH. THIS FEATURE WILL MOVE NORTHEASTWARD BY SUNSET.

HOWEVER...MORE SHOWERS AND STORMS HAVE FORMED NEAR THE
MINNESOTA/IOWA BORDER REGION THIS AFTERNOON. THESE ARE BEING DRIVEN
BY THE 850 MB LOW LEVEL JET AND ANOTHER WEAKER 500 MB VORTICITY
MAXIMUM. MESOSCALE MODELS ARE MIXED WITH THEIR HANDLING OF THE
CURRENT ACTIVITY. BEST ONES TAKE MOST OF THIS PRECIPITATION EAST
NORTHEAST AND MISS THE AREA.

THESE MODELS TRY TO DEVELOP MORE SHOWERS AND STORMS LATER THIS
EVENING AND OVERNIGHT...AS THE LOW LEVEL JET AXIS AND WARM CONVEYOR
BELT SHIFTS INTO THE AREA. 500 MB SHORTWAVE TROUGH ALSO APPROACHES
THE REGION. BEST SETUP APPEARS TO BE IN THE NORTHWEST PARTS OF THE
AREA. THUS...CONTINUED TO RAMP UP POPS TONIGHT.

SPC HAS PARTS OF AREA IN MARGINAL SEVERE RISK TONIGHT...WITH ENOUGH
ELEVATED CAPE AND EFFECTIVE SHEAR TO BRING A RISK FOR SOME HAIL.
HOWEVER...THIS SHOULD BE ISOLATED IN NATURE...DUE TO LACK OF FOCUSED
UPWARD VERTICAL MOTION. LOWS SHOULD DROP ONLY INTO THE MID 60S.

BETTER UPWARD VERTICAL MOTION COMES INTO THE AREA TUESDAY...AS
SEVERAL 500 MB VORTICITY MAXIMA PUSH NORTHEAST THROUGH THE AREA. THE
SURFACE TROUGH ALSO PUSHES EASTWARD TOWARD THE AREA. GOOD MIXING IN
THE LOW LEVELS ELIMINATES CAP...WITH WEAK MEAN LAYER CAPE WITH GOOD
DEEP LAYER SHEAR. NAM LOOKS OVERDONE WITH CAPE WITH DEW POINTS TOO
HIGH...WITH THE MORE CONSERVATIVE MEAN LAYER CAPE ON THE GFS MORE
REALISTIC. CONTINUED THE LIKELY THUNDER POPS FOR TUESDAY. HIGHS
SHOULD REACH THE UPPER 70S INLAND...WITH A POSSIBLE LAKE BREEZE
IN THE AFTERNOON KEEPING THINGS COOLER NEAR THE LAKE.

.TUESDAY NIGHT - CONFIDENCE...MEDIUM
500 MILLIBAR SHORTWAVE COMBINED WITH SFC/850 TROUGH AXIS EXPECTED
TO KEEP SCT SHRA/TSRA GOING THIS PERIOD. SOME DIURNAL DROPOFF
POSSIBLE BUT ENOUGH FORCING MECHANISMS AT PLAY TO KEEP THE CHANCE
GOING. SOUNDINGS CONTINUE TO SHOW A TALLER AND SKINNIER CAPE
PROFILE. MBE VELOCITIES ARE ALSO LESS THAN 10 KNOTS. SO POTENTIAL
FOR EFFICIENT RAIN MAKERS.

.WEDNESDAY - CONFIDENCE...MEDIUM
MID LEVEL SHORTWAVE AND LOW LEVEL TROUGH AXIS MOVE SLOW ENOUGH TO
KEEP THE CHANCE FOR SHRA/TSRA GOING FOR AT LEAST THE MORNING
HOURS. MAY GET INTO SOME SUBSIDENCE FOR THE AFTERNOON AS SHORTWAVE
MOVES EAST OF THE AREA. BRIEF 925 COOLING ASSOCIATED WITH TROUGH
BUT 925 TEMPS MODIFY BACK TO 18-20C DURING THE AFTERNOON.

.WEDNESDAY NIGHT AND THURSDAY - CONFIDENCE...MEDIUM
WILL GO WITH A QUIET PERIOD IS MID LEVEL RIDGING AND SURFACE HIGH
DOMINATE. RETURN FLOW LLJ SETS UP TO THE WEST OF THE AREA ON
THURSDAY. SOUTHERLY WINDS DO PICK UP A BIT WITH 925 TEMPS
19-21C...SO WARM DAY EXPECTED WITH LAKE BREEZE CIRCULATION
GENERATING AN ONSHORE COMPONENT.

.THURSDAY NIGHT - CONFIDENCE...MEDIUM
LEAD VORT MAXES AND EASTWARD TRANSLATION OF 850 JET SUGGEST
PRECIP DEVELOPMENT MAY OCCUR WITH AN UPTICK IN MOISTURE ADVECTION
AS WELL.

.FRIDAY THROUGH SATURDAY - CONFIDENCE...LOW TO MEDIUM
LOOKS LIKE AN ACTIVE PERIOD WITH SURFACE/850 FRONTS SLOWLY
SAGGING INTO SRN WI. MOISTURE/INSTABILITY LIKELY PLENTIFUL WITH
GRADUALLY INCREASING 500 MILLIBAR DYNAMICS AS WELL. BIGGER MODEL
DISCREPANCY COMES WITH HOW MUCH PRECIP LINGERS IN A POST FRONTAL
FASHION INTO SATURDAY. THE GEM IS THE MOST AGGRESSIVE BU THE ECMWF
IS NOT TOO FAR BEHIND. THE GFS TENDS TO SUPPRESS THIS FURTHER
SOUTH WITH MORE INFLUENCE OF THE COOL HIGH PRESSURE BUILDING IN.
IN FACT A NE WIND REGIME LOOKS LIKELY IN THE WAKE OF THE FRONT
WITH 925 WINDS RAMPING UP TO 35 KNOTS. SO A BIG DOWNTURN IN TEMPS
FROM FRIDAY APPEARS LIKELY.

.SUNDAY AND MONDAY - CONFIDENCE...LOW
MODELS CONTINUE TO DIVERGE WITH THE GFS SHOWING MORE PRECIP WITH
THE NEWD MOVEMENT OF PLAINS UPPER LOW INTO THE GREAT LAKES KEEPING
RAIN CHANCES ALIVE. MEANWHILE THE ECMWF SHOWS THE HIGH DOMINATING
WITH QUIET WX AND THE INFLUENCE OF THE LOW REMAINING SOUTH OF WI.
WILL CARRY SMALL PRECIP CHANCES PER THE SUPERBLEND GUID TO HANDLE
THIS DIFFERENCE.

&&

.AVIATION/00Z TAFS/...A FEW RAIN SHOWERS LINGERING IN THE AREA SHOULD
MOVE OUT BY EVENING. GUSTY SOUTHWEST WINDS ARE EXPECTED INTO EARLY
THIS EVENING...WITH GUSTS TO AROUND 25 KNOTS. SCATTERED CUMULUS
ALSO WILL LINGER UNTIL EARLY EVENING.

SOUTHWEST WINDS AT 1500 TO 2000 FEET ABOVE GROUND LEVEL WILL
APPROACH THE 35 TO 40 KNOT RANGE FOR A TIME LATER THIS EVENING INTO
THE OVERNIGHT HOURS. LEFT OUT OF TAFS DUE TO BORDERLINE NATURE...BUT
MAY NEED TO BE ADDED LATER IF THESE VALUES INCREASE.

SOUTH WINDS WILL WEAKEN SOMEWHAT TONIGHT INTO TUESDAY...AS A SURFACE
TROUGH MOVES TOWARD THE AREA FROM THE WEST. CHANCES FOR SHOWERS AND
STORMS WILL GRADUALLY INCREASE LATER TONIGHT INTO TUESDAY. VICINITY
THUNDERSTORM WORDING WILL BE USED FOR TUESDAY AT MADISON...IN THE
AFTERNOON IN THE EASTERN SITES. THERE IS SOME UNCERTAINTY WITH AREAL
COVERAGE AND TIMING OF ANY OF THESE SHOWERS/STORMS. MVFR
CEILINGS/VISIBILITIES ARE POSSIBLE IN ANY HEAVIER SHOWERS/STORMS.

&&

.MARINE...AS THE DEW POINTS REMAIN REASONABLY ABOVE THE WATER
TEMPERATURES FOR THE NEXT FEW DAYS...FOG MAY DEVELOP AT TIMES.
THIS WOULD BE ESPECIALLY TRUE TOWARD THE OPEN WATERS...MORE UNDER
THE INFLUENCE OF THE MARINE INVERSION. DENSE FOG IS POSSIBLE AT
NIGHT...IF WINDS GET LIGHT ENOUGH.

SMALL CRAFT ADVISORY CONTINUES ACROSS THE NEARSHORE WATERS UNTIL 09Z
TUESDAY...AS A TIGHT PRESSURE GRADIENT CONTINUES ACROSS THE AREA.
GUSTY SOUTHWEST WINDS ARE EXPECTED UNTIL EARLY EVENING...THEN
WEAKENING. GUSTS TO AROUND 25 KNOTS ARE EXPECTED INTO EARLY THIS
EVENING. HIGHEST WAVES WILL BE TOWARD THE OPEN WATERS. THE WINDS AND
WAVES WILL SUBSIDE BY LATER TONIGHT.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...SMALL CRAFT ADVISORY UNTIL 4 AM CDT TUESDAY FOR LMZ643>646.

&&

$$
TONIGHT/TUESDAY AND AVIATION/MARINE...WOOD
TUESDAY NIGHT THROUGH MONDAY...COLLAR


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