Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 250840
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
340 AM CDT MON AUG 25 2014

.TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH.

THE UPPER LEVEL JET MAX PUSHES ACROSS NORTHWEST WISCONSIN TODAY
AND ACROSS THE LAKE SUPERIOR REGION THIS EVENING AND TONIGHT. WITH
RATHER LIGHT SOUTHWEST FLOW ACROSS SOUTHEAST WISCONSIN. WEAK UPPER
DIVERGENCE TODAY WITH STRONGER UPPER DIVERGENCE TONIGHT ACROSS
SOUTHERN WISCONSIN...BUT SOME OF THIS MAY BE CONVECTIVE FEEDBACK.
THE STRONG MID LEVEL SHORTWAVE MOVES FROM THE LAKE WINNIPEG AREA
TO NEAR JAMES BAY CANADA TONIGHT.

WITH WEST/SOUTHWEST FLOW AT 700 MB WE STAY QUITE WARM WHILE THE
50 KNOT 700 MB SPEED MAX IS ACROSS NORTHERN WISCONSIN. THE 850 MB
THERMAL RIDGE WITH TEMPERATURES AROUND 22 CELSIUS EXTENDS ACROSS
SOUTHERN WISCONSIN TODAY AND FOR MUCH OF TONIGHT. 850 MB DEW
POINTS ARE QUITE MOIST...AROUND 14 TO 16 CELSIUS. A 20 KNOT 850 MB
SOUTHWEST WIND MOVES ACROSS SOUTHERN WISCONSIN THIS MORNING...BUT
THEN WE ARE MAINLY IN THE ENTRANCE REGION WITH THE STRONGEST WINDS
TO THE NORTH. 850 MB WINDS INCREASE TO AROUND 30 KNOTS LATE
TONIGHT AS THEY BECOME MORE WEST.

GENERALLY WEAK 700 MB UPWARD MOTION TODAY AND INTO LATE TONIGHT.

THE WIND CONVERGENCE ALONG THE APPROACHING COLD FRONT IS QUITE
WEAK...SO ONCE THE INITIAL BAND OF WEAKENING THUNDERSTORMS
DIMINISH...ADDITION REDEVELOPMENT IS LACKING A STRONG TRIGGER. THE
MOISTURE AND INSTABILITY IS IN PLACE...WITH ZERO TO 1 KM MIXED
LAYER CAPE REACHING 4000 JOULES/KG LATE THIS AFTERNOON. THERE WILL
BE A WEAK CAP IN PLACE BUT THIS WEAKENS DURING THE AFTERNOON. ALSO
ZERO TO 3 KM NAM EHI RISES TO AROUND 4.5.

THE LOCAL SEVERE WEATHER PARAMETER KEEPS THE BEST POTENTIAL OF
SEVERE WEATHER TO NORTHERN AREAS OF THE FORECAST AREA...UP TO 60
PERCENT AND A LITTLE HIGHER ACROSS NORTHEAST WISCONSIN. THE NAM
NSHARP FORECAST SOUNDINGS DO INDICATE A POTENTIAL FOR
SEVERE...ESPECIALLY NORTH TOWARDS FOND DU LAC...INCLUDING A SMALL
TORNADO POTENTIAL. AGAIN THE STRONG TRIGGER IS THE MAIN LIMITING
FACTOR.

A HOT AND HUMID DAY IS EXPECTED TODAY. AS HAS BEEN THE
CASE...MAIN ISSUE WILL BE THE EXTENT OF CLOUDS WITH THE
DIMINISHING AREA OF APPROACHING SHOWERS/THUNDERSTORMS AND ANY
CLOUDS TRAPPED BELOW THE CAP. CURRENT FORECAST TEMPS AND DEWPOINTS
RESULT IN MAX HEAT INDEX VALUES IN THE 95-100 RANGE. WITH
CONDITIONS BORDERLINE AND THE UNCERTAINTY IN CLOUDS/PRECIP...OPTED
TO CONTINUE TO NOT ISSUE A HEAT ADVISORY.

.SHORT TERM...TUESDAY THROUGH WEDNESDAY NIGHT...FORECAST
CONFIDENCE IS MEDIUM.

MODELS NOW ARE TAKING SURFACE COLD FRONT FURTHER SOUTH INTO NORTH
CENTRAL TO CENTRAL ILLINOIS ON TUESDAY...LINGERING THERE INTO
WEDNESDAY NIGHT. THIS SHIFT FURTHER TO THE SOUTH HAS RESULTED IN
THE MODELS KEEPING THE AREA MAINLY DRY ON TUESDAY...WITH SOME QPF
SHIFTING THROUGH THE AREA AT TIMES TUESDAY NIGHT INTO WEDNESDAY
NIGHT. THERE IS STILL SOME 850 MB CONFLUENCE/CONVERGENCE ACROSS
THE AREA DURING THIS TIME...THOUGH NOT MUCH ELSE AS FAR AS
ORGANIZED SYNOPTIC UPWARD VERTICAL MOTION.

AREA FORECAST SOUNDINGS ARE SHOWING MUCH LESS ELEVATED CAPE
DURING THIS PERIOD...WITH ALMOST NONE AT TIMES. FOR NOW...WILL
TRIM BACK POPS SOMEWHAT FROM NORTH TO SOUTH ACROSS THE AREA DURING
THIS PERIOD. WOULD NOT BE SURPRISED IF POPS NEED TO BE LOWERED
EVEN MORE...AS INFLUENCE OF HIGH TO THE NORTHEAST OF THE AREA
TENDS TO BRING MORE DRY AIR INTO THE AREA AND PUSHES PRECIPITATION
FURTHER TO THE SOUTH AND WEST.

CLOUDS FROM CONVECTION AND PRECIPITATION OVER AND/OR TO THE SOUTH
SHOULD KEEP TEMPERATURES COOLER THAN PREVIOUSLY FORECAST...THOUGH
DEW POINTS WILL REMAIN QUITE HUMID ON TUESDAY. MAY HAVE TO LOWER
HIGHS MORE IN LATER FORECASTS IF INFLUENCE OF HIGH HOLDS BACK
PRECIPITATION.

.LONG TERM...THURSDAY THROUGH SUNDAY...FORECAST CONFIDENCE IS
MEDIUM.

GFS AND ECMWF CONTINUE TO SHOW TIMING AND PLACEMENT DIFFERENCES
WITH SYSTEM MOVING THROUGH THE REGION THURSDAY INTO FRIDAY. THE
GFS TAKES SURFACE LOW AND COLD FRONT NORTHEAST THROUGH WISCONSIN
THURSDAY NIGHT...BRINGING A SWATH OF QPF THROUGH THE REGION FROM
THURSDAY INTO FRIDAY. IT THEN SHOWS A RELATIVELY DRY PERIOD WITH
HIGH PRESSURE TO THE NORTHEAST.

THE ECMWF KEEPS THE LOW FURTHER TO THE SOUTHWEST OF THE REGION
THURSDAY INTO FRIDAY...WITH A WARM FRONT BRINGING QPF TO THE AREA.
SURFACE LOW THEN WEAKENS BUT SHIFTS NORTHEAST THROUGH THE AREA
LATER IN THE WEEKEND...BRINGING MORE QPF TO THE AREA.

GIVEN THESE CONTINUED DIFFERENCES...WILL USE CONSENSUS BLEND OF
MODEL POPS AND TEMPERATURES. MORE SEASONABLE TEMPERATURES ARE
EXPECTED DURING THIS PERIOD...THOUGH IT STILL LOOKS SOMEWHAT HUMID
WITH DEW POINTS LINGERING IN THE 60S.

&&

.AVIATION/12Z TAFS/...

AREAS OF MVFR STRATUS TRAPPED BELOW A LOW LEVEL INVERSION EARLY
THIS MORNING. ALSO A LINE OF DIMINISHING THUNDERSTORMS WILL PUSH
INTO SOUTH CENTRAL WISCONSIN EARLY THIS MORNING. A FEW STORMS
COULD HOLD TOGETHER AS THEY PUSH INTO THE SOUTHEAST THIS MORNING.

EXPECT MAINLY VFR CIGS BY AFTERNOON AS THE LOW CLOUDS MIX OUT.
THERE WILL THEN BE A CHANCE OF THUNDERSTORMS REDEVELOPING ALONG A
WEAK COLD FRONT MOVING INTO SOUTH CENTRAL WISCONSIN BY EARLY
EVENING...THEN NEARING THE FAR SOUTHEAST AROUND SUNRISE TUESDAY.

&&

.MARINE...

A VERY MOIST AIR MASS MAY BRING SOME MORE FOG TO LAKE MICHIGAN
TODAY AND THIS EVENING. WINDS WILL BECOME MORE SOUTH...WHICH
SHOULD HELP TO LIMIT FOG IN THE NEARSHORE AREAS.

&&

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

$$

TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
TUESDAY THROUGH SUNDAY...WOOD


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