Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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000
FXUS63 KMKX 212059
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
400 PM CDT THU JUL 17 2014

.TONIGHT AND TUESDAY...FORECAST CONFIDENCE - MEDIUM.

QUIET WEATHER IS EXPECTED FOR THIS EVENING ACROSS THE AREA...AS WARM
AIR ADVECTION CONTINUES TO BRING A VERY WARM AND HUMID AIRMASS INTO
THE REGION. NAM AND 4KM WRF/NMM MODELS BRINGING A SWATH OF QPF
ACROSS WESTERN PORTIONS OF THE AREA LATER TONIGHT INTO EARLY TUESDAY
MORNING...ASSOCIATED WITH 850 MB LOW LEVEL JET AXIS. GFS/00Z ECMWF
WERE MORE SPOTTY DURING THIS TIME.

THIS WILL HAVE TO BATTLE STRONG CAP THAT WILL DEVELOP DURING THIS
TIME PER GFS FORECAST SOUNDINGS. NAM SOUNDINGS ARE MORE MOIST AND
DOES NOT SHOW IT...THOUGH LIKELY INFLUENCED BY SOME FEEDBACK ISSUES.
LEANING TOWARD THE DRIER SOLUTION...AS MAIN CONVECTION REMAINS WELL
NORTHWEST AND NORTH OF THE AREA. KEPT LOWER END POPS GOING IN THE
NORTHWEST HALF OF THE AREA. LOWS SHOULD REMAIN IN THE UPPER 60S TO
LOWER 70S WITH RISING DEW POINTS. WINDS SHOULD BE UP ENOUGH TO LIMIT
ANY FOG TO LOW LYING AREAS AT WORST.

925 MB TEMPERATURE FIELDS SUGGEST UPPER 80S TO AROUND 90 FOR HIGHS
ON TUESDAY...LOWER 90S IN THE WISCONSIN RIVER VALLEY. DEW POINTS
RISING INTO THE LOWER TO MID 70S WILL RESULT IN HEAT INDEX VALUES OF
95 TO 100 ACROSS MOST OF THE AREA. AFTER COORDINATION WITH
NEIGHBORING OFFICES...WILL HOLD OFF ON A HEAT ADVISORY. CONDITIONS
WILL BE CLOSE AND NEEDS FURTHER ANALYSIS BY NEXT SHIFTS. A SPECIAL
WEATHER STATEMENT WILL HIGHLIGHT THIS FOR NOW.

MODELS BRING COLD FRONT SOUTHEAST INTO THE AREA LATE TUESDAY
AFTERNOON. THEY ALL HAVE SOME QPF WITH THE FRONT. HOWEVER...CAP WILL
BE STRONG UNTIL LATE IN THE AFTERNOON...SO SOME UNCERTAINTY WITH HOW
WIDESPREAD ANY CONVECTION WILL BE. WENT WITH CHANCE/SCATTERED POPS
FOR NOW ON TUESDAY. SLIGHT RISK FOR SEVERE STORMS IN SPC DAY 2
OUTLOOK LOOKS GOOD. LARGE MEAN LAYER CAPES OF 3000 TO 4000 J/KG AND
25 TO 30 KNOTS OF DEEP LAYER SHEAR SHOULD SUPPORT MULTICELL
DEVELOPMENT...WITH DAMAGING WINDS AND LARGE HAIL THE MAIN HAZARDS.

.TUESDAY NIGHT...FORECAST CONFIDENCE - MEDIUM.

PULLED BACK POPS SLIGHTLY TO HIGH CHANCE IN THE EARLY
EVENING...MOSTLY DUE TO SLIGHTLY FASTER MOVEMENT OF COLD FRONT AND
SOUTHWEST LOW LEVEL WINDS.  FORCING FROM LOW LEVEL JET WILLBE
FARTHER EAST OVER THE CENTRAL GTLAKES BY 00Z.  HENCE EXPECT LESS
OVERALL COVERAGE OF CONVECTION.

NEVER THE LESS...SLIGHT RISK STILL VALID AS BULK SHEAR OF 35 TO
40KTS LIKELY WITH HIGH CAPE VALUES EXCEEDING 3000 J/KG.  SLIGHT
COOLING OF MID-LEVEL HEIGHTS WILL ERODE CAPPING INVERSION IN THE
LATE AFTN WHICH WILL HELP REALIZE STRONG INSTABILITY ALONG FRONT.
HENCE EXPECT SCT CONVECTION WITH THE POTENTIAL FOR LARGE HAIL AND
DAMAGING WINDS.

CDFNT MOVES THROUGH DURING THE EVENING ENDING THUNDERSTORMS BY LATE
EVENING WITH COOLER AND DRIER AIR SETTLING IN LATE IN THE NIGHT.

.WEDNESDAY THROUGH THURSDAY...FORECAST CONFIDENCE - HIGH.

A QUIET PERIOD AS NORTHWEST LOW LEVEL WINDS AND UPSTREAM RIDGING
HOLD SWAY THROUGH THE PERIOD.  MAY BE SOME PATCHY FOG LATER
WEDNESDAY NIGHT.

.THURSDAY NIGHT THROUGH MONDAY - FORECAST CONFIDENCE - MEDIUM
TRENDING TOWARD LOW.

LARGE UPSTREAM HIGH PRESSURE RIDGE CONTINUES TO PINCH OFF DEEPER
MOISTURE WELL TO THE SOUTH AND WEST OF THE AREA THROUGH THURSDAY
NIGHT.  UPSTREAM RIDGE BEGINS TO FLATTEN ON FRIDAY AS LOW PRESSURE
MOVES ACROSS SOUTHERN CANADA WITH WEAKER TROF EXTENDING SWD.
INCREASING SOUTHERLY WINDS THEN USHER WARMER...MORE HUMID AIR INTO
THE REGION FRIDAY NIGHT AND SATURDAY AHEAD OF APPROACHING TROUGH.
HOWEVER BOTH GFS AND ECMWF SHOW STRONGEST LOW LEVEL FORCING AND
ADVECTION REMAINING SOUTH OF WI DURING THIS PERIOD VCNTY OF SFC
WMFNT. FOR NOW WL CONTINUE CHANCE POPS FRI NGT AND SAT.  CONFIDENCE
FOR LATER PERIODS TRENDS DOWNWARD.  GFS CARRIES UPPER LOW OVER SRN
CANADA SLOWLY SOUTHEAST ACROSS WRN GTLAKES LATER IN THE WEEKEND AS
IT PHASES WITH LONG WAVE TROUGH NEAR HUDSON BAY.  ECMWF HAD BEEN
SHOWING THIS SCENARIO WITH EARLIER RUNS BUT HAS NOW TRENDED TOWARD
FLATTER NW STEERING FLOW SETTING UP OVER WI INTO EARLY NEXT WEEK
WITH MUCH WEAKER LOW PRESSURE TROUGH LINGERING OVER CENTRAL GTLAKES.
MAY NEED TO CARRY SOME LOW POPS IN ERN CWA IN LATER PERIODS DUE TO
PROXIMITY OF THIS TROUGH.  AFTER TUESDAY...THE HEAT AND HUMIDITY
SHOULD REMAIN WELL SOUTH OF THE AREA WITH TEMPERATURES AVERAGING
NEAR OR SLIGHTLY BELOW NORMAL FOR LATE JULY.

&&

.AVIATION/00Z TAFS/...

VFR CONDITIONS ARE EXPECTED FOR MOST OF TONIGHT AND TUESDAY. SOUTH
TO SOUTHWEST WINDS WILL CONTINUE TO BRING WARM AND HUMID CONDITIONS
INTO THE AREA DURING THIS TIME. MOST LINGERING DIURNAL CUMULUS
SHOULD LINGER UNTIL AROUND SUNSET.

SOUTH WINDS MAY WEAKEN ENOUGH BETWEEN 09Z AND 13Z TUESDAY TO ALLOW
FOR MVFR FOG TO DEVELOP AT KENOSHA AND PERHAPS MADISON AND WAUKESHA.
UNCERTAIN WITH THIS...SO ONLY KEPT VFR FOG IN KENOSHA TAF FOR NOW.
GUSTY SOUTH TO SOUTHWEST WINDS SHOULD DEVELOP TUESDAY...WITH GUSTS
TO AROUND 20 KNOTS AT TIMES.

OUTSIDE CHANCE FOR SHOWERS OR STORMS LATE TONIGHT INTO EARLY TUESDAY
MORNING AT MADISON...BUT LEFT OUT OF TAFS DUE TO LOW CONFIDENCE IN
IT HAPPENING.

COLD FRONT WITH SCATTERED THUNDERSTORMS SHOULD MOVE SOUTHEAST
THROUGH TAF SITES BETWEEN 22Z TUESDAY AND 06Z WEDNESDAY. MAY SEE
GUSTY WINDS AND HAIL WITH ANY STORMS...ALONG WITH IFR VISIBILITIES.
USED VICINITY THUNDER WORDING IN MILWAUKEE TAF FOR NOW.

&&

.MARINE...

SOUTH WINDS OF 15 TO 20 KNOTS ARE EXPECTED THIS AFTERNOON NORTH OF
PORT WASHINGTON. A FEW GUSTS TO 22 KNOTS ARE EXPECTED...BUT NOT
FREQUENT ENOUGH FOR A SMALL CRAFT ADVISORY. WAVES SHOULD BUILD TO 2
TO 4 FEET BY LATE AFTERNOON...THEN SUBSIDE TONIGHT WITH WEAKENING
WINDS.

MAY SEE FOG DEVELOP TONIGHT AND LINGER TUESDAY...WITH DEW POINTS
INCREASING ACROSS THE AREA. DENSE FOG MAY AN ISSUE...THOUGH NOT
CONVINCED YET GIVEN THE WINDS REMAINING AT LEAST IN THE 5 TO 10 KNOT
RANGE OVERNIGHT...MAINLY HIGHER. WILL CONTINUE TO MENTION IN
HAZARDOUS WEATHER OUTLOOK.

SMALL CRAFT ADVISORY IN EFFECT FOR TUESDAY INTO EARLY TUESDAY
EVENING FOR GUSTY SOUTH TO SOUTHWEST WINDS AND SOME HIGH WAVES.
TIGHT PRESSURE GRADIENT AHEAD OF COLD FRONT WILL LEAD TO THE GUSTY
WINDS.

ANOTHER SMALL CRAFT ADVISORY WILL BE NEEDED FOR LATER TUESDAY NIGHT
INTO WEDNESDAY NIGHT...AS A TIGHT PRESSURE GRADIENT DEVELOPS OVER
THE AREA. HIGH WAVES WILL OCCUR AS WELL DURING THIS TIME.

&&

.BEACHES...

MODERATE SWIM RISK WILL CONTINUE UNTIL EARLY EVENING AT SHEBOYGAN
COUNTY BEACHES DUE TO GUSTY WINDS AND WAVES. SHOULD SEE HIGH SWIM
RISK WEDNESDAY INTO WEDNESDAY NIGHT WITH GUSTY NORTH TO NORTHEAST
WINDS AND HIGH WAVES.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...

WI...NONE.
LM...SMALL CRAFT ADVY LMZ643>646 FROM 15Z/22 TO 02Z/23.

&&

$$

TONIGHT/TUESDAY AND AVIATION/MARINE/BEACHES...WOOD
TUESDAY NIGHT THROUGH MONDAY...MBK


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