Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 230333 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1033 PM CDT FRI AUG 22 2014

.UPDATE...

DENSE FOG ADVISORY FOR THE LAKE SHORE COUNTIES AS COOL...MOIST
FLOW OFF OF LAKE MICHIGAN BROUGHT DENSE FOG INTO THOSE COUNTIES.
MKE HAS JUST NOW REPORTED 1/4 MILE SFC VSBY. WILL MONITOR INLAND
COUNTIES FOR DENSE FOG POTENTIAL. EXPECT FOG TO FORM JUST ABOUT
EVERYWHERE BUT LOCATION OF WIDESPREAD DENSE FOG IS A QUESTION.
SREF 60-75 PCT OF VSBY LESS THAN 1 MILE ALONG THE LAKE AND THEN PUSHES
ACROSS THE NORTHERN-MOST COUNTIES CWA AFTER 06Z...WHILE NAM HAS
LOWEST VSBYS ACROSS THE SOUTHERN 2/3 AND ALONG THE LAKE.

STALLED LAKE BREEZE/WIND SHIFT LINE IS THE FOCUS FOR ISOLATED PO-
UP SHOWERS OVER SOUTH CENTRAL AND FAR SOUTHEAST WISCONSIN...WITH
HI-RES RAPID UPDATE MODELS SHOWING PCPN CHANCES DIMINISHING WITH
WEAKENING CONVERGENCE AS WINDS LIGHTEN AFTER 06Z.

&&

.AVIATION/06Z TAFS/...
LOOKING MORE CERTAIN IFR CONDITIONS WILL AFFECT ALL TAF SITES
OVERNIGHT...WITH LIFR AT EASTERN SITES. EXPECT SLOW IMPROVEMENT
AFTER 12Z TO MVFR AROUND 15Z TO 16Z. SHOWER CHANCES THE REST OF
TONIGHT ALONG STALLED FRONTAL BOUNDARY LOOK MINIMAL AND WILL NOT
AFFECT TAF SITES AFTER 06Z EXCEPT FOR POSSIBLY KMSN...BUT STILL
TOO LOW TO MENTION IN THE KMSN TAF.

CHANCES FOR THUNDER INCREASE FROM SOUTHWEST TO NORTHEAST SATURDAY
AFTERNOON AND EVENING WITH APPROACHING WARM FRONT...BUT MODELS
KEEP PCPN MAINLY OVER THE SW FORECAST AREA...WITH ONLY KMSN THE
ONLY TAF SITE BEING REACHED BY CURRENT MODEL QPF FIELDS. WILL
AWAIT COMPLETE 00Z DATA TO COME IN BEFORE TAF ISSUANCE...BUT RIGHT
NOW ONLY PLAN TO MENTION VCNTY THUNDER AT KMSN.

&&

.MARINE...

DENSE FOG ADVISORY IN EFFECT FOR ALL MARINE NEARSHORE ZONES UNTIL
10 AM SATURDAY FOR WIDESPREAD FOG WITH VSBYS OF 1 MILE OR LESS.

&&

.PREV DISCUSSION... /ISSUED 333 PM CDT FRI AUG 22 2014/

TONIGHT AND SATURDAY...FORECAST CONFIDENCE - MEDIUM.

COULD SEE A FEW SHOWERS/STORMS LATE AFTERNOON INTO TONIGHT...MAINLY
ACROSS THE WESTERN TWO THIRDS WHERE MODELS ARE FOCUSING CONVECTION
WITHIN SOME WEAK LOW LEVEL CONVERGENCE. OTHERWISE...MAIN CONCERN
TONIGHT WILL BE THE POSSIBILITY OF MORE FOG...POSSIBLY DENSE AGAIN.
CURRENT SKY COVER...WINDS...AND LOW LEVEL MOISTURE SUGGEST
CONDITIONS SIMILAR TO LAST NIGHT.

WILL BE A CHANCE FOR SHOWERS/STORMS TOMORROW...MAINLY ACROSS THE
SOUTHWEST FORECAST AREA IN THE AFTERNOON TOWARD BETTER WARM
ADVECTION ALOFT AND LOW LEVEL CONVERGENCE. 925 MB TEMPS WILL BE A
LITTLE COOLER THAN TODAY...SO EXPECTING HIGH TEMPS A LITTLE LOWER.
REGARDLESS...IT WILL STILL BE ANOTHER WARM AND HUMID DAY.

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

THE FEW THUNDERSTORMS THAT DEVELOP SATURDAY AFTERNOON MAY PERSIST
INTO SATURDAY NIGHT BEFORE DIMINISHING.  MUCH STRONGER FORCING TO
THE WEST WHERE LOW LEVEL JET AXIS WILL ARC FROM THE CENTRAL PLAINS
INTO ERN MN AND FAR WRN WI.  WEAK WARM MOISTURE FLUX CONVERGENCE
DOES SKIM SRN WI OVERNIGHT.  DESPITE UPPER LEVEL RIDGING SPREADING
INTO THE AREA...NOT ENOUGH CAPING ALOFT TO TOTALLY ELIMINATE SMALL
CHANCE FOR CONVECTION.

MID-LEVEL RIDGE SETTLES OVER AREA SUNDAY INTO SUNDAY EVENING BEFORE
BEGINNING TO SUCCUMB TO SRN EXTENSION OF VIGOROUS MID-LEVEL SHORT
WAVE MOVING ACROSS NORTHERN PLAINS/SOUTHERN CANADA AREA LATER SUN
NIGHT AND MON. WILL CONTINUE DRY FORECAST FOR BULK OF THIS PERIOD
DUE TO LACK OF SIGNIFICANT TRIGGER DESPITE LACK OF MID-LEVEL CAPING
AND LINGERING INSTABILITY.

SLIGHT MID-LEVEL COOLING AND SWD EXTENSION OF LOW LEVEL JET AFFECT
SRN WI LATE SUN NGT AND MON.  DESPITE LARGE SCALE BLOCKING HIGH
PRESSURE JUST TO THE SOUTHEAST...PREFER MORE PROGRESSIVE SOLUTION
OFFERED BY ECMWF/GEM W.R.T. SFC FRONT.  HENCE EXPC WEAKENING FRONTAL
BOUNDARY TO SLIDE ACROSS SRN WI ON MON.  WITH STRONGEST FORCING
REMAINING TO THE NORTH AND WEAKER SWLY LOW LEVEL FLOW...WL CONTINUE
MID-RANGE CHANCE POPS FOR CONVECTION AS FRONT MOVES THROUGH.

POTENTIAL FOR MORE FOG SATURDAY NIGHT BUT HELD OFF FROM INCLUDING IT
FOR NOW DUE TO BETTER BOUNDARY LAYER MIXING AND MORE MID-CLOUDS.

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

AS MENTIONED ABOVE...WILL LEAN MORE ON BLEND OF ECMWF/GEM GUIDANCE
FOR EARLY IN THE PERIOD WITH STRONGER WEST WINDS IN THE LOW LEVELS
CARRYING SFC FRONT FARTHER EAST AND SOUTH MONDAY NIGHT INTO TUESDAY.
FOR NOW DUE TO UNCERTAINTY...WL CARRY LOW POPS IN FOR THESE TIME
PERIODS BUT IF TREND CONTINUES...MAY BE ABLE TO REMOVE IN LATER
FORECASTS...ESPECIALLY MON NGT.

MEDIUM RANGE GUIDANCE IN REASONABLE AGREEMENT WITH FRONT BEGINNING
TO WAVER BACK TO THE NORTH MONDAY NIGHT INTO TUESDAY AS SOUTHERN
EXTENSION OF LONG WAVE TROUGH MOVES THROUGH THE CENTRAL AND NRN
PLAINS.  SFC FRONT THEN REMAINS IN THE AREA INTO THURSDAY BEFORE
STRONGER NORTH WINDS NUDGE BOUNDARY AND DEEPER MOISTURE TO THE
SOUTH.  HENCE WL NEED TO KEEP SMALL POPS IN MOST PERIODS WITH DRYING
TREND BEGINNING THU INTO THU NGT.

SUNDAY AND MONDAY STILL LOOK TO BE THE WARMEST DAYS WITH MORE
SEASONAL CONDITIONS THE REST OF THE WEEK...AND SLIGHTLY LESS
HUMIDITY WITH A FURTHER DECREASE IN HUMIDITY LATE IN THE WEEK.

AVIATION/00Z TAFS/...

LOOKS LIKE A DECENT CHANCE FOR MORE WIDESPREAD FOG TONIGHT INTO
SATURDAY MORNING.

COULD SEE A STRAY SHOWER OR STORM THIS AFTERNOON INTO EARLY
EVENING...BUT OTHERWISE IT LOOKS MAINLY DRY THROUGH TONIGHT. THERE
WILL BE A CHANCE FOR SHOWERS AND STORMS SATURDAY...ESPECIALLY FROM
MADISON SOUTHWESTWARD IN THE AFTERNOON.

MARINE...

A VERY MOIST AIRMASS AND OVER THE RELATIVELY COOLER WATERS OF LAKE
MICHIGAN HAS LED TO CONTINUED DENSE FOG OVER THE NEARSHORE WATERS
NORTH OF MILWAUKEE. THERE IS CURRENTLY NO REASON TO BELIEVE THERE
WILL BE MUCH CHANGE IN CONDITIONS TONIGHT INTO SATURDAY MORNING...SO
THE ADVISORY HAS BEEN EXTENDED FOR THESE NORTHERN ZONES.

FARTHER SOUTH...THE FOG HAS CLEARED OUT FOR NOW. THERE IS A GOOD
CHANCE DENSE FOG WILL RETURN BY LATE EVENING...SO ANOTHER ADVISORY
MAY BE EVENTUALLY NEEDED FOR THE SOUTHERN MARINE ZONES.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 10 AM CDT SATURDAY FOR WIZ052-060-066-
     071-072.

LM...DENSE FOG ADVISORY UNTIL 10 AM CDT SATURDAY FOR LMZ643>646.

&&

$$

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


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