Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 172049
AFDMKX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
349 PM CDT FRI APR 17 2015

.SHORT TERM...

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

ABOVE NORMAL TEMPERATURES AND CLEARING SKIES WILL PERSIST INTO THE
NIGHT BEFORE A COLD FRONT PUSHES SOUTH THROUGH THE STATE EARLY ON
SATURDAY MORNING. THIS FRONT WILL BRING COOLER TEMPERATURES AND
PERHAPS SOME LOW CLOUDS...ESPECIALLY NEAR LAKE MICHIGAN...BUT NO
PRECIP IS EXPECTED WITH THE FRONTAL PASSAGE. BEHIND THE FRONT...
WINDS WILL BE OUT OF THE EAST AT 15 KTS GUSTING UP TO 20. GUSTS
SHOULD EASE IN THE AFTERNOON. THESE EAST WINDS WILL BRING COOLER
TEMPERATURES THAN WHAT WE HAVE HAD IN THE LAST FEW DAYS.

.SATURDAY NIGHT AND SUNDAY...FORECAST CONFIDENCE MEDIUM

SATURDAY NIGHT LOOKS TO BE QUIET UNTIL AN AREA OF LOW PRESSURE
SWINGS THROUGH THE UPPER MIDWEST STATES. LARGE SCALE JET STREAK OF
120 KTS WILL SUPPORT UPPER LEVEL DIVERGENT FLOW OVER THE REGION.
ALSO...A 500MB SHORTWAVE TROUGH WILL ALSO PROVIDE SUPPORT FOR
PRECIPITATION. 12Z NAM IS GOING DRY FOR OUR FORECAST AREA EXCEPT FOR
OUR WESTERN COUNTIES...FROM MADISON AND POINTS WEST. THE GFS IS
FOLLOWING SUIT FOR PRECIP CHANCES...WHILE THE ECMWF IS STAYING DRY
UNTIL SUNDAY AFTERNOON.

A SECOND AREA OF LOW PRESSURE WILL MOVE INTO THE REGION FROM THE
SOUTHERN PLAINS. A BAND OF FRONTOGENETICAL FORCING ALONG WITH SOME
POSITIVE VORTICITY ADVECTION AT THE 500 MB LEVEL WILL RAMP UP RAIN
CHANCES SUNDAY AFTERNOON...ALONG WITH CHANCES OF THUNDERSTORMS AS
MODEL SOUNDINGS INDICATE ELEVATED INSTABILITY OF NEARLY 150 J/KG.
MODEL FORECAST SOUNDINGS ALSO INDICATE APPRECIABLE MOISTENING OF THE
LOW LEVELS AS THIS SYSTEM MOVES THROUGH.

.LONG TERM...

.MONDAY AND TUESDAY...FORECAST CONFIDENCE MEDIUM

LINGERING MOISTURE WILL CONTINUE RAIN CHANCES THROUGH MONDAY MORNING
UNTIL THE LOW PRESSURE SYSTEM MOVES OFF TO THE NORTHEAST. 12Z NAM
SOUNDINGS INDICATE RAIN CEASING BY MONDAY EVENING...WHILE THE ECMWF
KEEPS PRECIPITATION CHANCES AROUND INTO TUESDAY. THE GFS SEEMS TO
END PRECIPITATION BY MONDAY EVENING AS WELL. I WENT WITH THE MODEL
BLENDS DUE TO THE UNCERTAINTY OF THE ENDING TIME OF THE
PRECIPITATION...AND KEPT CHANCES OF PRECIPITATION THROUGH TUESDAY.

AS THE LOW PRESSURE MOVES OFF TO THE NORTHEAST...WINDS WILL VEER
FROM THE NORTHWEST AND INTENSIFY AS SFC PRESSURE GRADIENT TIGHTENS.
THIS WILL SUPPORT COLD AIR ADVECTION AND BRING IN 925MB TEMPERATURES
BACK TO NEGATIVE SINGLE DIGITS. THESE COOLER TEMPERATURES WILL
PERSIST FOR THE REST OF THE WEEK...AS LOWS WILL BE IN THE LOWER TO
MID 30S TUESDAY THROUGH FRIDAY. SOME PLACES COULD SEE SLIGHTLY BELOW
FREEZING SFC TEMPERATURES...ESPECIALLY IN OUR NORTHWESTERN COUNTIES.
THESE TEMPERATURE PROFILES COULD SUPPORT A RAIN/SNOW MIX TUESDAY.

TUESDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE MEDIUM

SOME UNCERTAINTY EXISTS REGARDING THE MODEL SOLUTIONS FOR TUESDAY
NIGHT THROUGH FRIDAY...AS THE GFS IS SHOWING A CLIPPER SYSTEM
RAPIDLY MOVING THROUGH THE REGION...BRINGING PRECIPITATION CHANCES
WEDNESDAY MORNING. THE 17.12Z ECMWF MODEL RUN IS SHOWING A SIMILAR
CLIPPER SYSTEM...UNLIKE THE PREVIOUS 17.06Z ECMWF MODEL RUN. WITH
THE COLDER TEMPERATURES...PRECIPITATION TYPE WILL DEPEND ON THE
LOCATION OF PRECIPITATION IN OUR FORECAST AREA. TEMPERATURES ACROSS
OUR NORTHERN COUNTIES COULD BE NEAR FREEZING...INDICATING MORE SNOW.
BUT...TEMPERATURES IN OUR SOUTHERN COUNTIES COULD BE ABOVE FREEZING.
SO...CHANCES OF RAIN/SNOW MIX WEDNESDAY MORNING WILL DEPEND ON
LOCATION OF PRECIPITATION AND TEMPERATURES.

THURSDAY LOOKS TO BE DRY...AS BOTH THE ECMWF AND GFS MODELS ARE NOT
PROGGING ANY PRECIPITATION. THIS PATTERN LOOKS TO PERSIST INTO
FRIDAY.

&&

.AVIATION/00Z TAFS/...PRIMARY CONCERN FOR AVIATION IS THE PASSAGE OF
A COLD FRONT EARLY SATURDAY MORNING. AS THE FRONT PASSES...WINDS
WILL SWING FROM THE WEST TO THE NORTH BEFORE SETTLING ENE AROUND 15
KTS. THERE MAY BE SOME LOW CLOUDS ACCOMPANYING THE FRONT...BUT DO
NOT HAVE ENOUGH CONFIDENCE TO PUT IT IN.

&&

.MARINE...SMALL CRAFT CRITERIA WILL BE APPROACHED...AND PERHAPS
BRIEFLY MET...FOR A FEW HOURS SATURDAY MORNING BEHIND A COLD FRONT
THAT WILL PUSH SOUTH THROUGH WISCONSIN. PERSISTENT NE WINDS MAY LEAD
TO SMALL CRAFT CONDITIONS SATURDAY NIGHT AND SUNDAY.

&&

.FIRE WEATHER...

NEAR-CRITICAL FIRE WEATHER CONDITIONS WILL EXIST TOWARD CENTRAL
WISCONSIN ON SATURDAY AFTERNOON. A COLD FRONT WILL PUSH SOUTH
THROUGH THE STATE EARLY ON SATURDAY MORNING. BEHIND THIS FRONT...THE
RELATIVE HUMIDITY WILL DROP INTO THE 20 TO 30 PERCENT RANGE INLAND
WITH EAST WINDS AROUND 14 KTS.

&&

.MKX WATCHES/WARNINGS/ADVISORIES...

WI...NONE.
LM...NONE.

&&

$$

TONIGHT/SATURDAY AND AVIATION/MARINE...BSH
SATURDAY NIGHT THROUGH FRIDAY...JTS



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