Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 010829
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
329 AM CDT SAT AUG 1 2015

.TODAY - CONFIDENCE...MEDIUM.

COMPACT STRONG SURGE OF LOW LEVEL MOISTURE AND WARM AIR ADVECTION
TRIGGERING ISOLATED SHOWERS AND STORMS IN SOUTHEAST MN.  SFC
DEWPOINTS INCREASE FROM THE LOWER 50S ACROSS SRN WI TO THE UPPER 50S
TO LOWER 60S ACROSS NRN IA/SRN WI. STORMS ARE MOVING SOUTHEAST ALONG
DENSITY DISCONTINUITY AND WILL LIKELY AFFECT WESTERN AND SOUTHERN
PORTIONS OF CWA THIS MRNG AS SURGE OF LOW LEVEL MOISTURE FLUX
CONVERGENCE PASSES ACROSS THE AREA.  FOR NOW...WL GO WITH ISOLD
WORDING BUT MAY HAVE TO INCREASE TO MORE SCT IN WEST FOR AN HOUR OR
TWO.  SURGE OF MOISTURE FLUX CONVERGENCE MOVES SOUTH OF BORDER BY
AFTN SO DRY CONDITIONS EXPECTED.  925H TEMPS WARM TO 22-24C SO
DAYTIME TEMPS SHOULD EASILY RETURN TO THE 80S. WINDS NOT EXPECTED TO
BE AS BREEZY TODAY DUE TO SLIGHTLY WEAKER PRESSURE GRADIENT BUT
SHOULD STILL BE IN THE 10 TO 20KT RANGE.  THIS SHOULD BE STRONG
ENOUGH TO PREVENT LAKE BREEZE FROM DEVELOPING...OR ELSE HOLDING IT
CLOSE TO THE SHORE THIS AFTN.

.TONIGHT - CONFIDENCE...MEDIUM.

EXPECTING A QUIET EVENING ACROSS MOST OF THE AREA.  MODERATE MID
LEVEL STEERING FLOW IS EXPECTED TO CARRY AMPLIFYING LOW PRESSURE
TROF INTO THE NORTHERN PLAINS TONIGHT.  STRENGTHENING LOW LEVEL JET
AHEAD OF THIS TROF TO 35 TO 45 KNOTS PIVOTS INTO CENTRAL AND SRN WI
AFT 06Z/SUN. STRONG SURGE OF MOISTURE FLUX CONVERGENCE SPREADS INTO
WESTERN CWA LATE TNGT.  MESO-SCALE CONVECTIVE SYSTEM EXPECTED TO
DEVELOP IN THE NORTHERN PLAINS THIS EVENING AND FOLLOW EXPANDING
INSTABILITY GRADIENT TO THE EAST-SOUTHEAST WHICH MAY CARRY MCS INTO
SRN WI.  NOT ENOUGH CONFIDENCE AT THIS POINT TO BUMP UP POPS TO
LIKELY DUE TO DISAGREEMENT BETWEEN SHORT TERM GUIDANCE ON TRACK OF
MCS.  HOWEVER WITH LLJ SPREADING ACROSS SRN WI LATE TNGT...WL CONT
HIGHER CHANCE POPS AND SWITCH TO SCT WORDING IN WEST.  ELEVATED
CAPES EXCEED 1000 J/KG LATE TNGT IN SOUTH CENTRAL WI WITH 30KTS OF
BULK SHEAR.  HENCE SLT RISK FOR SEVERE FOCUSING ON HAIL AND WIND
SEEMS WARRANTED.

.SUNDAY...FORECAST CONFIDENCE...MEDIUM

STILL QUITE A FEW QUESTIONS WITH THE SUNDAY FORECAST. FIRST...WILL
LIKELY BE DEALING WITH THE EXITING OVERNIGHT THUNDERSTORM COMPLEX AT
DAYBREAK. WILL PROBABLY BE QUITE A BIT OF CONVECTIVE DEBRIS LIMITING
HEATING EARLY IN THE DAY. LOW LEVEL JET WILL SLIDE SOUTHEASTWARD
ACROSS THE FORECAST AREA DURING THE DAY. STRONG LOW LEVEL FLOW WITH
THIS JET AHEAD OF AN APPROACHING COLD FRONT WILL DRAW WARM AND HUMID
CONDITIONS INTO SOUTHERN WISCONSIN. DEPENDING ON HOW QUICKLY CLOUDS
CAN MOVE OUT AND INSTABILITY BUILDS...COULD SEE SOME DEVELOPMENT
AHEAD OF THE FRONT BY EARLY AFTERNOON. BETTER CHANCE WILL COME LATE
AFTERNOON AND EVENING AS THE FRONT PUSHES SOUTHEAST THROUGH THE
FORECAST AREA. EVEN IF 2M DEWPOINTS ARE A BIT OVERDONE...STILL
SHOULD SEE PLENTY OF INSTABILITY GIVEN ENOUGH HEATING. MID LEVEL
LAPSE RATES PROGGED TO BE IN THE 7-8C RANGE BY MID/LATE AFTERNOON.
BULK SHEAR FROM 0-6 KM STILL AROUND 35-40 KNOTS IN MODELS. NOT
SURPRISING SPC HAS THE SOUTHEAST HALF OF THE FORECAST IN A SLIGHT
RISK FOR SEVERE STORMS...WITH THE NORTHWEST IN A MARGINAL RISK.

OTHER CONCERN FOR SUNDAY IS HOW WARM IT GETS. NAM/GFS 925 MB AND 2
METER TEMPS QUITE WARM. LATEST ECMWF HAS TRENDED THAT WAY...BUT IS
NOT QUITE AS WARM AS NAM/GFS SOLUTIONS. OPTED TO WARM TEMPS A BIT
FROM PREVIOUS FORECAST...BUT DID NOT GO AS NEARLY AS WARM AS WARMEST
MODELS WOULD SUGGEST GIVEN A GOOD DEAL OF UNCERTAINTY IN TIMING OF
PRECIP AND CLOUD COVER. POTENTIAL EXISTS FOR EVEN WARMER TEMPS IF
THE SUN DOES COME OUT FOR A SIGNIFICANT AMOUNT OF TIME.

.MONDAY THROUGH FRIDAY...FORECAST CONFIDENCE...MEDIUM

EXPECT DRY WEATHER MONDAY AS HIGH PRESSURE BEGINS TO BUILD IN FROM
THE NORTHWEST AND MODEL PRECIPITABLE WATER VALUES DROP TO AROUND
HALF OF AN INCH. SHOULD BE DRY THEN TUESDAY AND WEDNESDAY UNDER
THE HIGH. HAVE SOME LOW POPS IN THE FORECAST FOR LATER THURSDAY
INTO FRIDAY AS ANOTHER WAVE TRAVERSES THE AREA.

HIGH TEMPS MON/TUE LOOK TO BE WITHIN A COUPLE DEGREES OF
NORMAL...COOLING A FEW DEGREES FOR WED-FRI UNDER PERSISTENT
NORTHWEST FLOW ALOFT.

&&

.AVIATION/12Z TAFS/...EXPECT ISOLD SHOWERS TO AFFECT SOUTH CENTRAL
WI EARLY THIS MORNING.  MAY EVEN BE A RUMBLE OF THUNDER.  MAY NEED
TO USE A VCTY REMARK IN KMSN TAF FOR AN HOUR OR TWO.  OTRW VFR
CONDITIONS FOR THE BULK OF THE TAF PERIOD.  SCT T MAY RESULT IN
LOWER CIGS LATE TONIGHT...ESPECIALLY AT KMSN.

&&

.MARINE...NOT AS BREEZY TODAY ACROSS THE NEARSHORE WATERS DUE TO
WEAKER PRESSURE GRADIENT AND SLIGHTLY WEAKER WINDS IN THE LOW
LEVELS.  STILL MAY HAVE GUSTS TO AROUND 20 KTS LATER THIS MORNING
AND AFTERNOON.

SMALL CRAFT CONDITIONS MAY RETURN LATE TONIGHT BUT MORE LIKELY ON
SUNDAY AHEAD OF A COLD FRONT THAT WILL MOVE ACROSS THE NEAR SHORE
WATERS LATE IN THE AFTERNOON AND EARLY EVENING.  SOME STRONG TSTORMS
MAY ACCOMPANY FRONTAL PASSAGE.

&&

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

$$

TODAY/TONIGHT AND AVIATION/MARINE...MBK
SUNDAY THROUGH FRIDAY...DDV


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