Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 180832
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
332 AM CDT MON AUG 18 2014

.SHORT TERM...

TODAY AND TONIGHT...FORECAST CONFIDENCE - MEDIUM.

LIGHT WINDS AND CLEAR SKIES ON THE WESTERN PERIPHERY OF THE
INCREASING STRATUS AND FOG SHIELD EXPANDING OVER EASTERN CWA HAS LED
TO DENSE FOG IN THE JANESVILLE AREA EXTENDING EAST TO AROUND
ELKHORN.  EXPECT ST AND FOG SHIELD TO CONTINUE EXPANDING WWD INTO
MORE OF SOUTH CENTRAL WI NEXT SEVERAL HOURS.  WL NEED TO KEEP AN EYE
ON OBS AND WEBCAMS AS PATCHY DENSE FOG CONTINUES TO EXPAND FARTHER
NORTH.  FOR NOW WL ISSUE DENSE FOG ADVY FOR FAR SOUTHERN THREE
COUNTIES AS WALWORTH CO DISPATCH REPORTED AREAS OF DENSE FOG IN THE
COUNTY AS WELL.  EXPECT DENSE FOG TO SPREAD INTO GREEN COUNTY NEXT
SEVERAL HOURS.  WEBCAMS SHOW DENSE FOG MORE PATCHY IN SHEBOYGAN AREA
DESPITE ONE HALF MILE VSBY AT KSBM. VSBYS CONTINUE TO FLUCTUATE AT
KSBM AND KETB.

OTRW...WEAK MID-LEVEL SHORT WAVE OVER SRN WI MAY CAUSE A FEW SHOWERS
OR TSTORMS TO GRAZE NORTHWEST CWA EARLY THIS MRNG.  FOR NOW WL KEEP
POPS SMALL BUT MAY NEED TO BUMP UP TO SCT WORDING IN THIS AREA.
BETTER CHANCE FOR MORE WIDESPREAD CONVECTION THIS AFTERNOON AND
TONIGHT.  THIS AFTN...UPSTREAM STRONGER SHORT WAVE OVER ERN SD MOVES
ACROSS SRN WI THIS AFTN AS DEEPER COLUMN MOISTURE SETTLES IN.
BETTER ISENTROPIC OMEGA ON 310 THETA SURFACE ALONG WITH LOWER
CONDENSATION PRESSURE DEFICITS THIS AFTN AS WELL.  HENCE WL CONTINUE
WITH HIGH CHANCE TO LOW CATEGORICAL POPS IN THE WEST LATE THIS AFTN.
SPREAD CATEGORICAL POPS EWD ACROSS CWA DURING THE NIGHT AS LOW LEVEL
JET PIVOTS ACROSS SRN WI AND INCREASES A BIT AS LOW PRESSURE ALOFT
STRENGTHENS A BIT.  PWAT VALUES INCREASE TO 1.5 TO 1.9 INCHES DURING
THIS PERIOD WITH APPROACHES TWO STANDARD DEVIATIONS AT KGRB FOR MID-
AUGUST.  BESIDES MOISTURE...SEVERAL OTHER FACTORS FAVOR HEAVY
RAINFALL POTENTIAL TONIGHT INCLUDING DEEP WARM CLOUD DEPTH OF 9500
FT AND CORFIDI VECTORS LESS THAN 10 KNOTS UNTIL LATE TONIGHT.  ADDED
HEAVY RAINFALL MENTION TO FORECAST FOR LATE AFTN AND TNGT AND WL
INCLUDE IN HWO.  DRIER AIR ROTATING AROUND DEEPING LOW PRESSURE
SHOULD HELP TO DECREASE CONVECTION LATER TONIGHT.

TUESDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE MEDIUM.

THE 500MB SHORTWAVE TROUGH WILL STALL OVER THE WESTERN GREAT LAKES
THROUGH WEDNESDAY MORNING. ONGOING SHOWERS AND THUNDERSTORMS MONDAY
NIGHT WILL TAPER OFF FROM SOUTHWEST TO NORTHEAST ACROSS THE MKX
FORECAST AREA ON TUESDAY AS DRY AIR WRAPS INTO THE REGION. EVEN
THOUGH MANY MODELS END PRECIP IN SOUTH CENTRAL WI BY TUE
AFTERNOON...OPTED TO KEEP LOW POPS IN. THE UPPER LOW WILL STILL BE
OVERHEAD...LEADING TO STEEP LOW LEVEL LAPSE RATES AND THE POTENTIAL
FOR A FEW SHOWERS OR THUNDERSTORMS DUE TO WEAK VORTICITY MAXIMA
ROTATING IN.

WEAK FLOW AND RECENT RAIN SHOULD LEAD TO PATCHY FOG OR AREAS OF
FOG...OVER SOUTH CENTRAL WI LATER TUE NIGHT. STRATUS CLOUDS COULD BE
A LIMITING FACTOR FOR DENSE FOG.

THE UPPER LOW WILL SHIFT EAST ON WEDNESDAY AND WEAK RIDGING WILL
MOVE IN. MOST OF THE MODELS ARE DRY ACROSS THE MKX FORECAST
AREA...SO FINALLY WENT DRY FOR THE FORECAST. WARMER AIR WILL BE
WORKING ITS WAY INTO SOUTH CENTRAL WI AS WELL.

.LONG TERM...

WEDNESDAY NIGHT THROUGH THURSDAY...FORECAST CONFIDENCE MEDIUM.

AN 850MB BAROCLINIC ZONE OVER THE MIDWEST WILL LIFT NORTHWARD INTO
SOUTHERN WI WEDNESDAY NIGHT. THE NOSE OF THE LOW LEVEL JET WILL BE
POINTING RIGHT INTO NORTHEAST IOWA BY LATE THU NIGHT AT THE SAME
TIME THE RIGHT ENTRANCE REGION OF THE UPPER JET MOVES OVERHEAD.
MODELS ARE SUGGESTING A CONVECTIVE COMPLEX WILL DEVELOP IN THE
MN/IA/WESTERN WI AREA AND SLIDE EAST THROUGH SOUTHERN WI EARLY THU
MORNING. WITH HIGH PRECIPITABLE WATER VALUES OF NEARLY 2 INCHES
SPREADING IN...PERIODS OF HEAVY RAIN WILL BE POSSIBLE. PRECIP SHOULD
TAPER OFF THU AFTERNOON AS THE SYSTEM WEAKENS.

PRECIP WILL HAVE A LARGE IMPACT ON TEMPERATURES. THE FORECAST HIGHS
AROUND 80 ARE ASSUMING SHOWERS AND STORMS.

FRIDAY THROUGH SUNDAY...FORECAST CONFIDENCE LOW.

THAT 850MB BAROCLINIC ZONE WILL WAFFLE OVER SOUTHERN/CENTRAL WI
THROUGH THE WEEKEND. THE 00Z ECMWF CAME INTO BETTER AGREEMENT WITH
THE GFS WITH THE FRONT STALLING OVER SOUTHERN WI. SHOWERS AND
THUNDERSTORMS WILL RE-DEVELOP AT TIMES ALONG THIS FRONT...
ESPECIALLY EACH AFTERNOON/EVENING.

THIS SHOULD BE A WARM AND HUMID PERIOD.

&&

.AVIATION/12Z TAFS/...

MOSTLY STRATUS WITH AREAS OF FOG CONTINUING TO SPREAD WWD ACROSS
EASTERN HALF OF CWA EARLY THIS MRNG.  ON WESTERN PERIPHERY OF ST
FIELD...CLEAR SKIES AND LIGHT WINDS HAS ALLOWED PATCHY DENSE FOG TO
DEVELOP IN KJVL AREA WHICH MAY SPREAD NORTH INTO KMSN NEXT SEVERAL
HOURS.  OTRW...MOIST LOW LEVEL FLOW ALLOWING OTHER AREAS OF MVFR
STRATUS AND FOG TO DEVELOP FARTHER SOUTHWEST.  THINKING LOW CLOUDS
AND FOG WL SLOWLY ERODE LATER THIS MRNG INTO THE AFTN WITH LOW
CLOUDS POTENTIALLY RETURNING TNGT ALONG WITH MORE WIDESPREAD
CONVECTION.

&&

.MARINE...

FOG IS THE MAIN ISSUE FOR NEXT SEVERAL DAYS.  MAY BE SOME PATCHY FOG
AROUND THIS MRNG IN LIGHT MOIST FLOW.  WL NEED TO WATCH FOR FOG
RETURNING TNGT AS SLY SFC WNDS CARRY HIGHER DEWPTS AND MOISTURE
ACROSS LAKE MI NEARSHORE WATERS.  WINDS LOOK TO REMAIN BELOW SMALL
CRAFT ADVY LEVELS FOR THE FORESEEABLE FUTURE.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...DENSE FOG ADVISORY UNTIL 9 AM CDT THIS MORNING FOR WIZ068>070.

LM...NONE.
&&

$$

TODAY/TONIGHT AND AVIATION/MARINE...MBK
TUESDAY THROUGH SUNDAY...MRC


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