Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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758
FXUS63 KMKX 161716 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1216 PM CDT SAT MAY 16 2015

.UPDATE...

SHOWERS ASSOCIATED WITH 850MB WARM AIR ADVECTION AND MOISTURE
CONVERGENCE ARE DISSIPATING ACROSS SOUTHERN WI LATE THIS MORNING.
THERE ARE BREAKS IN THE CLOUDS AND TEMPERATURES SHOULD GET UP TO
AROUND 80 INLAND TODAY. A PERSISTENT LAKE BREEZE WILL KEEP LAKESHORE
TEMPS DOWN AROUND 60 TO 65 TODAY.

WIDELY SCATTERED THUNDERSTORMS ARE EXPECTED THIS AFTERNOON AS A WEAK
MID LEVEL SHORTWAVE APPROACHES FROM IA/IL. MODELS ARE SHOWING TALL
SKINNY CAPE VALUES OF 1000 TO 1500 J/KG INLAND FROM THE LAKESHORE
THIS AFTERNOON. THERE IS NOT MUCH SHEAR... SO ONLY BRIEF SMALL HAIL
WOULD BE POSSIBLE IN ANY STRONGER STORMS WEST OF MADISON IN THE
HIGHER CAPE AREA. THE MAIN THREAT WILL BE BRIEF HEAVY RAIN SINCE
PRECIPITABLE WATER VALUES ARE AROUND 1.2 INCHES TODAY.

&&

.AVIATION/18Z TAFS/...

DENSE MARINE FOG MAY SPREAD INLAND TO KMKE AND KRAC EARLY THIS
AFTERNOON. WILL NOT ADD INTO THE MKE TAF YET... BUT BE AWARE FOR THE
POTENTIAL. DENSE FOG WILL BE A POSSIBILITY ONCE AGAIN AT KSBM...
KMKE... KRAC AND KENW TONIGHT.

SHOWERS DISSIPATED THIS MORNING. MVFR CUMULUS CLOUDS ARE DEVELOPING
FROM SOUTH TO NORTH EARLY THIS AFTERNOON. A FEW WIDELY SCATTERED
THUNDERSTORMS WILL BE POSSIBLE ACROSS SOUTHERN WI THIS AFTERNOON.
SMALL HAIL IS POSSIBLE FROM MADISON AND WEST... BUT BRIEF PERIODS OF
HEAVY RAIN IS THE MAIN THREAT.

&&

.MARINE...

EXPANDED THE MARINE DENSE FOG ADVISORY TO INCLUDE ALL OF THE NSH
ZONES UNTIL 15Z SUNDAY. NOT ANTICIPATING MUCH CHANGE IN CONDITIONS
HERE TODAY INTO EARLY SUNDAY...WITH LIGHT WINDS ALLOWING FOR DENSE
FOG TO CONTINUE OVER THE COOL LAKE WATERS.

&&

.PREV DISCUSSION... /ISSUED 330 AM CDT SAT MAY 16 2015/

TODAY AND TONIGHT...FORECAST CONFIDENCE IS MEDIUM.

CONTINUED DENSE FOG ADVISORY FOR SHEBOYGAN AND OZAUKEE COUNTIES
UNTIL 15Z TODAY...AS KSBM IS STILL REPORTING 1/4 MILE VISIBILITIES
WITH A GOOD AMOUNT OF FOG ON AREA WEB CAMERAS. DENSE FOG TO THE
NORTH OF SHBOYGAN COUNTY IMPROVED QUITE A BIT IN THE PAST FEW
HOURS. HAVING SOME DIFFICULTY WITH GRASPING TRENDS WITH THIS DENSE
FOG...SO WILL CONTINUE TO MONITOR CONDITIONS. MAY CANCEL
ADVISORY EARLY IF VISIBILITIES IMPROVE.

KEPT FOG OVER LAKE MICHIGAN AND REMOVED FROM REST OF LAKESHORE
COUNTIES THIS MORNING...AS FOG HAS NOT DEVELOPED AS QUICKLY AS
PREVIOUSLY ANTICIPATED. MAY STILL SEE LIGHT FOG IN THIS AREA...BUT
THINK THAT MIDDLE TO HIGH CLOUDS HAS LIMITED TEMPERATURE FALL AND
KEPT ENOUGH OF A DEW POINT DEPRESSION TO LIMIT FOG DEVELOPMENT.

SCATTERED TO NUMEROUS RAIN SHOWERS ARE EXPECTED TO SHIFT NORTHEAST
THROUGH PARTS OF THE AREA INTO THE EARLY MORNING HOURS TODAY. THIS
WAS BEING DRIVEN BY A PASSING 500 MB VORTICITY MAXIMUM AND MODEST
850 MB WARM AIR ADVECTION REGIME. HIGH RESOLUTION MODELS SHOW THIS
ACTIVITY DIMINISHING SOMEWHAT AS THE MORNING GOES ON.

MODELS IN DECENT AGREEMENT WITH SURFACE WARM FRONT SHIFTING
NORTHWARD THROUGH THE AREA TODAY...THEN NORTH OF THE AREA TONIGHT.
UPWARD VERTICAL MOTION FIELDS WITH THE FRONT ARE WEAK TO MODEST AT
BEST...WITH THE LOW LEVEL JET FOCUSING WEST OF THE AREA TODAY INTO
TONIGHT. AREA FORECAST SOUNDINGS DO SHOW LOW LEVELS MIXING OUT WITH
500 TO 1000 J/KG TALL AND SKINNY MEAN LAYER CAPES...WITH WEAK DEEP
LAYER SHEAR.

THINK ANY SHOWER/STORM ACTIVITY LATER TODAY INTO THIS EVENING WILL
BE SCATTERED IN NATURE...DESPITE LITTLE TO NO CIN. ANY STORMS WILL
BE CAPABLE OF HEAVY RAINFALL WITH SLOW STORM MOTIONS AND DECENT
PRECIPITABLE WATER VALUES. CHANCES FOR POPS WILL BE BEST IN THE FAR
WEST TONIGHT...CLOSER TO THE LOW LEVEL JET AXIS. COULD BE DRY FOR
MOST OF TONIGHT GIVEN LACK OF DECENT UPWARD VERTICAL MOTION FIELDS.

ONSHORE WINDS WILL KEEP LAKESHORE AREAS TODAY IN THE UPPER 50S TO
60S...WITH INLAND AREAS REACHING TO AROUND 80 DEGREES. THIS SHOULD
OCCUR AS LONG AS CLOUDS THIN OUT AS EXPECTED LATER TODAY. MILD LOWS
IN THE 60S INLAND WITH 50S LAKESIDE ARE FORECAST.

SUNDAY AND SUNDAY NIGHT - CONFIDENCE...MEDIUM
CONCERN FOCUSES ON POTENTIAL FOR SVR WX. IMPRESSIVELY DYNAMIC
NEGATIVE TILT MID LEVEL LOW WILL ROTATE NEWD FROM NEB/SD AREA TO
MN ARROWHEAD. GREATEST INFLUENCE OF THIS FEATURE WILL BE IN THE
18-06Z TIME FRAME DUE FIRST FROM INITIAL DCVA WITH WEAKER WAVE
THEN A BIT MORE INFLUENCE OF THE PRIMARY SYSTEM COMBINED WITH
INCREASING 850 JET AND 250 MILLIBAR JET LATER IN THE AFTERNOON
INTO THE EVENING HOURS. SURFACE FLOW PROGGD TO REMAIN SOUTHERLY
INTO THE EVENING WHEN PRE-FRONTAL TROUGH ARRIVES AND SHIFTS WINDS
MORE TO THE SW. ANY BREAKS FROM EARLY CONVECTION WILL SEND CAPE
VALUES OVER 1000 J/KG AS THE WARM AND MOIST AIRMASS BUILDS. 0-6 KM
SHEAR AND 0-1KM SHEAR VALUES REACH THE FAVORED 40/20 KNOT
THRESHOLDS DURING THIS TIME. CWASP VALUES ARE ALL IN THE 70S AND
SOME VERY IMPRESSIVE CIPS PERCENTAGES BEING GENERATED. SOME CWASP
VALUES REACH 80 NEAR AND WEST OF KMSN WHICH DOES HAVE SOME BETTER
PROXIMITY TO LLJ AXIS AND SLIGHTLY BETTER DYNAMICS FROM 250 JET
CORE. SITUATION BEARS WATCHING AS CONVECTIVE SEVERITY WILL BE
DRIVEN BY DEGREE OF CLEARING AND SUBSEQUENT INSTAB THAT EVOLVES
AFTER EARLIER CONVECTION. SPC HAS MAINTAINED THE SLIGHT RISK FOR
ENTIRE CWA...NO SURPRISE THERE.

MONDAY - CONFIDENCE...MEDIUM
SURFACE LOW LIFTS NE OF LAKE SUPERIOR WITH A MUCH DRIER AIRMASS
TAKING HOLD. 925/850 THERMAL RIDGING COLLAPSES. GUSTY WESTERLY
WIND WITH DECENT MIXING. TEMPS SHOULD REACH THE LOW 70S ESP IN SE
WI WITH LINGERING WARMER 925 TEMPS THERE. OVERALL BREEZY AND STILL
MILD THOUGH DRIER DEW POINTS REPLACE THE MOIST AIRMASS.

TUESDAY - CONFIDENCE...MEDIUM
LOW LEVEL THERMAL TROUGH SETTLES ACROSS THE STATE WITH 850 TEMPS
A COUPLE DEGREES CELSIUS EITHER SIDE OF ZERO 0C. VORT ACTION
REMAINS ACROSS LAKE SUPERIOR REGION WITH FAIRLY TRANQUIL WNW 500
FLOW ACROSS SRN WI.

WEDNESDAY THROUGH FRIDAY - CONFIDENCE...MEDIUM
SURFACE/850 ANTICYCLONE LOOKS TO BE THE DOMINANT FEATURE THIS
PERIOD WITH GRADUAL WARMING TEMPERATURES. HOWEVER ONSHORE FLOW
WILL KEEP EASTERN AREAS COOLER. MID LEVEL SHORTWAVE LIFTS OUT OF
THE ROCKIES THOUGH THIS OPENS UP TO A RATHER FLAT WAVE WITH EVEN
THE MORE STRONGER SOLUTIONS SHOWING MOISTURE WITH THIS FEATURE
STAYING LARGELY SOUTH OF WI. PER COLLAB WITH SURROUNDING OFFICES
WILL LEAVE DRY FORECAST INTACT THIS PERIOD.

AVIATION/12Z TAFS/...FOG MAY NOT BE AS MUCH OF AN ISSUE AT THE
EASTERN SITES AS PREVIOUSLY FORECAST...AND WILL IMPROVE VISIBILITIES
TO MVFR/VFR CATEGORY BY 12Z TAF ISSUANCES. SOME UNCERTAINTY HERE
..BUT LEANING TOWARD THE IMPROVEMENT OCCURRING AND LINGERING THROUGH
THE MORNING. LIGHT EAST SOUTHEAST WINDS ARE EXPECTED TODAY...WITH
LIGHT SOUTHEAST WINDS TONIGHT.

SOME DIURNAL CUMUMULS DEVELOPMENT IS EXPECTED AT MADISON AND THE
EASTERN SITES THIS AFTERNOON...AS MIDDLE TO HIGH CLOUDS MOVE OUT OF
THE AREA. KEPT VICINITY THUNDER WORDING IN TAFS FOR THIS AFTERNOON
AND EARLY EVENING...WITH SCATTERED SHOWERS AND STORMS POSSIBLE.
HEAVY RAINFALL MAY OCCUR WITH THE STORMS...WITH REDUCED VISIBILITIES.

MARINE...CONTINUED MARINE DENSE FOG ADVISORY FOR THE NORTHERN
MOST MARINE ZONE UNTIL 15Z SUNDAY. NOT ANTICIPATING MUCH CHANGE
IN CONDITIONS HERE TODAY INTO EARLY SUNDAY...WITH LIGHT WINDS
ALLOWING FOR DENSE FOG TO CONTINUE OVER THE COOL LAKE WATERS. THE
REST OF THE NEARSHORE WATERS SHOULD SEE JUST PATCHY FOG DURING
THIS TIME...THOUGH SOME UNCERTAINTY HERE SO WILL CONTINUE TO
MONITOR CONDITIONS.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...DENSE FOG ADVISORY UNTIL 10 AM CDT SUNDAY FOR LMZ643>646.

&&

$$

UPDATE...MRC
TODAY/TONIGHT AND AVIATION/MARINE...WOOD
SUNDAY THROUGH FRIDAY...COLLAR



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