Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 291018 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
518 AM CDT FRI AUG 29 2014

.TODAY AND TONIGHT...FORECAST CONFIDENCE MEDIUM.

INFLUENCE OF DRY SOUTHEAST FLOW AROUND WESTERN FLANK OF DEPARTING
HIGH PRESSURE EVIDENT IN TIGHT SURFACE DEW POINT GRADIENT THAT
REMAINS ALONG IL/WI BORDER AND THE MS RIVER VALLEY.

SHOWERS ACROSS CENTRAL/NE WI IN REGION OF 850 MB FRONTOGENETIC
RESPONSE TO 20-30 KT WINDS ACROSS EAST-WEST 850 MB BAROCLINIC ZONE
BISECTING THE STATE.

MCV-DRIVEN POCKET OF SHOWERS/THUNDERSTORMS IN NORTHEAST IOWA IS
WEAKENING AS IT LIFTS NE TOWARD SW WI AND INTO THE DRIER...MORE
STABLE AIR...WITH THE MCV SHEARING OUT/ WEAKENING AS IT MOVES INTO
THE MEAN RIDGE POSITION. HOWEVER MOISTURE TRANSPORT INTO STATE ON 30
KT 850 MB WINDS ALONG WITH ADDITIONAL FORCING FOR ASCENT FROM UPPER
LEVEL DIFFLUENCE/DIVERGENCE WILL BE ENOUGH TO SUPPORT THE SHOWERS
ACROSS THE NORTHWEST HALF OF THE FORECAST AREA THIS MORNING...WITH
SOME SCATTERED SHOWERS IN THE SOUTHEAST. A FEW RUMBLES OF THUNDER
ARE POSSIBLE.

MODELS INDICATE A BREAK IN THE PCPN LATE THIS MORNING INTO THIS
AFTERNOON. UPPER RIDGING SLOWLY MOVING EAST WITH APPROACHING TROUGH
OMEGA INCREASES AS LLJ STRENGTHENS LATE THIS AFTERNOON AND EVENING
AS MAIN 500 MB TROUGH MOVES INTO WRN WI BY 12Z SAT.

NORTHWEST HALF OF FORECAST AREA IN FAVORABLE AREA FOR HEAVY RAIN
TONIGHT AS CAPE IS TALL AND SKINNY WITH CORFIDI VECTORS HOVERING
AROUND 10KTS...WITH PRECIP WATER VALUES RISING FROM 1.6 TO 2 INCHES.
WPC HAS LOCATIONS NORTHWEST OF A PORT WASHINGTON...FORT ATKINSON TO
MONROE LINE ARE IN A SLIGHT RISK FOR RAINFALL TO EXCEED FLASH FLOOD
GUIDANCE.

HOWEVER...WITH PREVIOUS 24 HOURS MUCH DRIER THAN ORIGINALLY FORECAST
AND HIGHEST WPC-BASED QPF TOTALS THROUGH SATURDAY MORNING TO THE
NORTH AND WEST OF THE FORECAST AREA...WITH IN-CWA TOTALS BELOW THE
1 TO 6-HOUR FLASH FLOOD GUIDANCE BETWEEN 2 AND 3 INCHES...WILL
KEEP THE ESF STATEMENT GOING FOR LOCALIZED URBAN/SMALL STREAM
FLOODING POTENTIAL BUT NO FLASH FLOOD WATCH AT THIS TIME.

SPC HAS A 5 PCT CHANCE FOR WIND GUSTS WITH STEEP LOW-LEVEL LAPSE
RATES PRODUCING AN INVERTED V DRY ADIABATIC PROFILE UP TO 4K TO 5K
FT ON WESTERN CWA FORECAST SOUNDINGS LATE THIS AFTERNOON/EARLY
EVENING IF FORECAST CAPE VALUES CAN BE REALIZED.

.SATURDAY AND SUNDAY...FORECAST CONFIDENCE...MEDIUM

LATEST MODEL GUIDANCE SUGGEST THAT A SURFACE FRONTAL BOUNDARY AND
UPPER LEVEL SHORTWAVE AXIS WILL BE POSITIONED JUST TO THE WEST OF
THE FORECAST AREA SATURDAY MORNING. SHOWERS AND STORMS ARE LIKELY
AHEAD OF THESE DURING SATURDAY MORNING...WITH A CHANCE CONTINUING
INTO THE AFTERNOON AS THE TROUGH MOVES THROUGH AND THE FRONT
STALLS NEAR THE WI/IL BORDER.

ANOTHER SHORTWAVE WILL MOVE THROUGH SATURDAY EVENING AND
OVERNIGHT...BUT KEPT THE FORECAST DRY DUE TO MUCH DRIER AIR ALOFT.
SUNDAY THEN LOOKS LIKE A PLEASANT DAY IN BETWEEN LOW PRESSURE
SYSTEMS.

HIGH TEMPERATURES SATURDAY SHOULD BE RIGHT AROUND NORMAL...RISING
TO A COUPLE DEGREES ABOVE NORMAL FOR SUNDAY.

.MONDAY THROUGH THURSDAY...FORECAST CONFIDENCE...MEDIUM

SHOWERS AND STORMS ARE LIKELY IN THE WEST BY DAYBREAK MONDAY
MORNING AND THEN ACROSS THE FORECAST AREA DURING THE DAY AS A
COLD FRONT MOVES THROUGH. SOME STRONGER STORMS ARE POSSIBLE
MONDAY...BUT THIS WILL BE DEPENDENT ON THE TIMING OF THE FRONT. IT
LOOKS LIKE A DECENT AMOUNT OF INSTABILITY TO GO ALONG WITH AROUND
40 KNOTS OF 0-6 KM BULK SHEAR. MODELS ARE HINTING AT THE FRONT
MOVING THROUGH EARLIER IN THE DAY THOUGH...WHICH WOULD LIMIT
THE TIME FOR DAYTIME HEATING AND RESULTANT DESTABILIZATION.

IT LOOKS MAINLY DRY TUESDAY AND WEDNESDAY WITH THE FRONTAL
BOUNDARY AND HIGHER MOISTURE/INSTABILITY REMAINING SOUTH.

A RETURN OF MOISTURE UNDER SOUTHERLY LOW LEVEL FLOW MAY BRING
SHOWERS AND STORMS BACK TO THE AREA FOR THURSDAY.

TEMPERATURES FOR THE MONDAY THROUGH THURSDAY TIME PERIOD SHOULD
REMAIN NEAR TO A COUPLE DEGREES ABOVE NORMAL.

.AVIATION/12Z TAFS/...MOISTURE ADVECTION IS BRINGING IN SOME MVFR/IFR
CIGS AND REDUCED VISIBILITIES ALONG AND JUST AHEAD OF THE SURFACE
WARM FRONT. THESE LOWER CIGS/VSBYS SHOULD CLEAR THE TAF SITES BY
LATE MORNING AS THE FRONT LIFTS NORTH THEN STALLS OVER CENTRAL
WISCONSIN. SOME CONCERN FOR KMKE...AND POSSIBLY KENW...THAT IF
WINDS ARE MORE SOUTHEAST THAN SOUTH TODAY THAT THE FRONT MAY NOT
CLEAR TO THE NORTH AND WILL LEAVE THOSE SITES WITH LESS THAN VFR
CONDITIONS THE ENTIRE DAY.

WILL GO WITH THE CONSENSUS OF THE MODEL GUIDANCE AND GO WITH
PREVAILING VFR TODAY...WITH BRIEF MVFR CIGS/VSBYS WITH SCATTERED
SHOWER AND ISOLATED THUNDERSTORMS PASSING THROUGH WITH THE FRONT
THIS MORNING.

LIKELY TO SEE MVFR SHOWERS AND THUNDERSTORMS SPREAD FROM WEST TO
EAST LATER THIS AFTERNOON AND EVENING WITH LOW PRESSURE PASSING
THROUGH THE REGION. AGAIN WILL GO WITH NO LOWER THAN MVFR
CIGS/VSBYS FOR NOW...THOUGH IFR VSBYS IN HEAVY RAIN
POSSIBLE...ESPECIALLY AT KMSN. NAM GUIDANCE HINTING AT IFR/LIFR
CIGS AS THE PCPN TAPERS OFF TOWARDS 12Z SATURDAY...BUT CONSENSUS
TRACK OF THE LOW KEEPS ENOUGH GRADIENT AT TAF SITES TO KEEP LOW
LEVELS MIXED WELL ENOUGH TO PREVENT LOW STRATUS AND FOG...BUT IT
WILL HAVE TO BE WATCHED FOR WITH THE NEXT ROUND OF MODEL DATA.

.MARINE...SOUTHEAST TO SOUTH WINDS WILL GUST TO BETWEEN 20 AND 25
KNOTS AS LOW PRESSURE APPROACHES...BUT NOT FREQUENTLY ENOUGH OR
LONG ENOUGH TO WARRANT A SMALL CRAFT ADVISORY AT THIS TIME.
HOWEVER SMALL VESSEL OPERATORS SHOULD EXERCISE
CAUTION...ESPECIALLY NORTH OF MILWAUKEE WHERE THE LONGER FETCH
WILL BUILD HIGHER WAVES.

.BEACHES...THERE IS A MODERATE SWIM RISK AT THE LAKE MICHIGAN
BEACHES FROM SHEBOYGAN TO KENOSHA THIS MORNING THROUGH THIS
EVENING WHERE SOUTHEAST TO SOUTH WINDS INCREASING TO 10 TO 20
KNOTS WILL BUILD HIGH WAVES AND RESULT IN STRONG CURRENTS ALONG
THE SHORE.

RACINE COUNTY IS LISTED AS HAVING A LOW RISK IN THE SURF ZONE
FORECAST AS SOME SHELTERING DUE TO SHORELINE TOPOGRAPHY RESULTED
IN SLIGHTLY LOWER AVERAGE WAVE HEIGHTS...BUT SWIMMERS SHOULD STILL
BE ALERT FOR STRONG CURRENTS AND HIGHER WAVES AT WINDWARD-FACING
BEACHES.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...NONE.
LM...NONE.
&&

$$

TODAY/TONIGHT AND AVIATION/MARINE...REM
SATURDAY THROUGH THURSDAY...DDV



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