Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 231620 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1120 AM CDT SAT MAY 23 2015

.UPDATE...

ANOTHER NICE DAY IS EXPECTED TODAY...WITH A DRY AIRMASS IN PLACE
ACROSS THE AREA. MID TO HIGH CLOUDS WILL GRADUALLY MOVE INTO THE
AREA FROM THE SOUTHWEST LATER THIS AFTERNOON.

500 MB VORTICITY MAXIMUM AND 700 FRONTOGENESIS RESPONSE
FIELDS...ASSOCIATED WITH SHOWERS IN MINNESOTA...EXTENDS INTO THE
AREA INTO EARLY THIS AFTERNOON. HOWEVER...DRY AIR BELOW 6000 FEET
ABOVE GROUND LEVEL AND MODEST MOISTURE ABOVE IT SHOULD PREVENT ANY
SHOWER ACTIVITY.

BUMPED UP HIGHS A FEW DEGREES...GIVEN CURRENT TRENDS. HIGHS SHOULD
REACH THE UPPER 70S INLAND...WITH LAKE BREEZE DEVELOPING EARLY
THIS AFTERNOON AND COOLING THINGS DOWN NEAR THE LAKE.

&&

.AVIATION/18Z TAFS/...

VFR CONDITIONS ARE EXPECTED THIS AFTERNOON...TONIGHT AND SUNDAY
MORNING ACROSS TAF SITES. MIDDLE TO HIGH CLOUDS WILL GRADUALLY
SPREAD NORTHEAST INTO THE AREA LATER THIS AFTERNOON INTO
TONIGHT...REMAINING CLOUDY ON SUNDAY. LIGHT SOUTH WINDS ARE
EXPECTED AT MADISON...WITH SOUTHEAST LAKE BREEZE DEVELOPING AT
EASTERN SITES EARLY THIS AFTERNOON. WINDS WILL REMAIN SOUTH
TONIGHT AND THEN SOUTHEAST ON SUNDAY...INCREASING DURING THE
AFTERNOON.

MAIN AREA OF SHOWERS SHOULD MOVE NORTHWARD INTO MADISON BY MID TO
LATE MORNING SUNDAY...AND THE EASTERN SITES EARLY SUNDAY
AFTERNOON. THIS ACTIVITY WILL BE MORE SCATTERED TOWARD THE EASTERN
SITES. WILL NOT MENTION THUNDER IN TAFS SUNDAY...AS RISK IS LOW
WITH STABLE AIRMASS IN PLACE. MAY SEE MVFR CATEGORY CEILINGS AND
VISIBILITIES DEVELOP WITH THE SHOWERS AT TIMES.

&&

.PREV DISCUSSION... /ISSUED 350 AM CDT SAT MAY 23 2015/

SHORT TERM...

TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH.

AN UPPER LEVEL RIDGE BUILDS ACROSS THE UPPER MISSISSIPPI VALLEY AS A
JET MAX INCREASES IN THE NORTHWEST FLOW OVER WISCONSIN...LIFTING TO
THE NORTHERN GREAT LAKES LATE TONIGHT. GENERALLY WEAK UPPER LEVEL
DIVERGENCE ACROSS SOUTHERN WISCONSIN.  AN NARROW ELONGATED AREA OF
CYCLONIC VORTICITY LIFTS NORTH TROUGH SOUTHERN WISCONSIN TODAY MID
LEVEL RH INCREASES TODAY AND TONIGHT WITH BANDS OF WEAK UPWARD
MOTION MOVING IN FROM THE SOUTHWEST.  THE 850/700 MB WINDS ARE
FAIRLY WEAK AS THE LOWER AND MID LEVEL RIDGE EXTENDS ACROSS THE
FORECAST AREA.  THE DEVELOPING SOUTH 850 MB FLOW BEGINS TO PUSH
TOWARD SOUTH CENTRAL WISCONSIN BY SUNRISE SUNDAY BUT THE 850/700 MB
MOISTURE CONVERGENCE STAYS SOUTHWEST.  THE NAM/GFS AND ECMWF ARE ALL
DRY THROUGH TONIGHT.  LOW CHANCE OF SHOWERS LATE TONIGHT WITH THE
APPROACHING INCREASE IN 850/700 MB WIND MAXIMA...AND SOME MAINLY MID
LEVEL VIRGA POSSIBLE WITH THE INCREASING MID LEVEL MOISTURE TODAY.

WITH THE WEAK SURFACE RIDGE...A LAKE BREEZE WILL COOL THINGS OFF
NEAR LAKE MICHIGAN IN THE AFTERNOON.

SUNDAY... FORECAST CONFIDENCE MEDIUM.

THE LOW LEVEL JET STRENGTHENS OVER THE MIDWEST AND POINTS INTO
SOUTHERN WI SUNDAY THROUGH MONDAY WHILE SEVERAL ROUNDS OF MID LEVEL
SHORTWAVES MOVE ACROSS WI. THERE IS A SLOWING TREND WITH THE PRECIP
ARRIVING INTO SOUTHERN WI... SO REDUCED POPS FOR THE FIRST PART OF
SUNDAY MORNING. AS IS THE CASE WITH ANY SHORTWAVE AND WARM AIR
ADVECTION- INDUCED PRECIP... TIMING OF THE ROUNDS OF PRECIP IS
UNCERTAIN.

THE FIRST WAVE OF SHOWERS AND A FEW EMBEDDED THUNDERSTORMS SHOULD
LIFT THROUGH SOUTHERN WI LATE SUNDAY MORNING WITH A 500MB SHORTWAVE
AND 850MB-700MB FRONTOGENESIS ON THE NOSE OF A LOW LEVEL JET. THE
MOIST PROFILE WITH HIGH PRECIPITABLE WATER VALUES WILL LEAD TO
LIMITED INSTABILITY. THE NAM IS DRIEST WITH THIS FEATURE AND KEEPS
SOUTHEAST WI MOSTLY DRY.

ANOTHER SHORTWAVE IS EXPECTED TO LIFT THROUGH THE AREA EITHER LATE
SUNDAY AFTERNOON OR SUNDAY EVENING. THE LOWEST CHANCE FOR PRECIP ON
SUNDAY WILL BE IN SOUTHEAST WI. OVERALL... THE HIGHEST CHANCES WILL
BE WEST AND NORTH OF MADISON.

CLOUDS AND PRECIP WILL KEEP TEMPERATURES MODERATED IN THE LOWER 70S
INLAND. INCREASING SOUTHEAST WINDS WILL LEAD TO COOLER LAKESHORE
AREA TEMPERATURES.

BY LATE SUNDAY NIGHT... THE STRONGEST AXIS OF THE LLJ WILL POINT
INTO NORTHEAST IOWA AND SOUTHEAST MN. THIS SHOULD CAUSE A BREAK IN
PRECIP FOR SOUTHEAST WI... SO I REDUCED POPS DOWN TO CHANCE THERE.
MEANWHILE... A LOW LEVEL TROUGH AXIS WILL TRACK FROM NORTHEAST IOWA
AND SOUTHWEST WI INTO SOUTH CENTRAL WI LATE SUNDAY NIGHT. KEPT
LIKELY POPS FOR THIS AREA.

LONG TERM...

MEMORIAL DAY... FORECAST CONFIDENCE MEDIUM.

THAT TROUGH AXIS WILL CONTINUE TO TRACK THROUGH SOUTHEAST WI MONDAY
MORNING. INSTABILITY IS STILL WEAK WITH THIS FEATURE... THUS
KEPT THE LIKELY RAIN SHOWERS WITH A CHANCE FOR THUNDERSTORMS WORDING.

MODELS ARE COMING INTO GREAT AGREEMENT THAT THE DRY SLOT WILL WRAP
INTO SOUTHERN WI MONDAY AFTERNOON. WITH THE WARM SECTOR OVER THE
AREA... INSTABILITY INCREASES SIGNIFICANTLY... ESPECIALLY WITH THE
NAM MODEL. BULK SHEAR BECOMES HIGH AS WELL WITH ANOTHER PUSH OF THE
LOW LEVEL JET INTO THE REGION. THE CWASP VALUES ON THE NAM ARE
AROUND 85 AND LOWER 70S FOR THE GFS. SPC ALSO NOTED THE STRONG
INSTABILITY AND ADDED MOST OF WISCONSIN TO THE MARGINAL... 5
PERCENT... RISK FOR SEVERE WEATHER. THE INGREDIENT LACKING MONDAY
AFTERNOON IN SOUTHERN WI WILL BE A TRIGGER MECHANISM TO GET
THUNDERSTORMS. WE WILL BE CAPPED AROUND 750-800MB DURING THE DAYTIME
HOURS... BUT A SURFACE TROUGH TRACKING INTO SOUTH CENTRAL WI EARLY
MONDAY EVENING MAY BE ENOUGH TO INDUCE A FEW THUNDERSTORMS THAT HAVE
THE POTENTIAL TO BE STRONG. WE WILL CONTINUE TO KEEP AN EYE ON THIS
SCENARIO.

THE DRY WARM SECTOR OVER SOUTHERN WI MONDAY AFTERNOON WILL ALLOW FOR
SOME SUNSHINE AND HIGHS IN THE UPPER 70S TO AROUND 80 INLAND. IT
SHOULD TURN OUT TO BE A VERY NICE MEMORIAL DAY AFTERNOON.

TUESDAY THROUGH FRIDAY... FORECAST CONFIDENCE MEDIUM.

THE MAIN SURFACE TROUGH FROM THAT CLOSED UPPER LOW OVER THE UPPER
MIDWEST WILL FINALLY SLIDE THROUGH SOUTHEAST WI TUESDAY. THE TROUGH
MAY STALL AND LEAD TO LINGERING SHOWER CHANCES TUESDAY NIGHT INTO
WEDNESDAY... ALTHOUGH WEDNESDAY IS LOOKING DRIER WITH THE LATEST
MODEL RUNS.

MODELS DIFFER WITH TIMING OF SHORT WAVE ENERGY IN A SOUTHWESTERLY
FLOW REGIME...LEADING TO A CHANCE FOR SHOWERS AND SLIGHT CHANCE FOR
THUNDERSTORMS THURSDAY INTO THE WEEKEND. NEXT WEEKEND MAY END UP
BEING A WET ONE AGAIN.

TEMPERATURES LOOK TO REMAIN AT OR ABOVE SEASONAL NORMS THROUGH THE
PERIOD.

AVIATION/12Z TAFS/...

VFR CONDITIONS EXPECTED WITH A RIDGE OF HIGH PRESSURE OVER THE GREAT
LAKES.  INCREASING MID LEVEL CLOUDS EXPECTED. SOME MAINLY VIRGA
POSSIBLE.

MARINE...

INCREASING SOUTH WINDS ARE EXPECTED TO OCCUR ON MEMORIAL DAY...AS A
TIGHT PRESSURE GRADIENT DEVELOPS WITH LOW PRESSURE OVER MINNESOTA. A
SMALL CRAFT ADVISORY MAY BE NEEDED FOR LATER SUNDAY NIGHT
AND MEMORIAL DAY.

&&

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

$$

UPDATE...WOOD
TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
SUNDAY THROUGH FRIDAY...MRC



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