Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI

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FXUS63 KMKX 171717 AAA
AFDMKX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
1217 PM CDT FRI APR 17 2015

.UPDATE...

HIGH PRESSURE AND CLEAR SKIES OVER THE STATE WILL MAKE FOR A
BEAUTIFUL AFTERNOON...WITH HIGHS MAKING IT INTO THE UPPER 70S
INLAND...AND PERHAPS TOUCHING 80 IN A FEW SPOTS. HOWEVER LAKE BREEZE
SHOULD MAKE IT WELL INLAND THIS AFTERNOON...LIMITING HIGHS EAST OF
APPROX A FOND DU LAC TO DELEVAN LINE TO THE LOW TO MID 70S. ENDED UP
SPEEDING UP THE LAKE BREEZE...AND HAD TO INCREASE TEMPS A FEW
DEGREES ACROSS THE AREA GIVEN AM TEMP TRENDS.

AFTER A NIGHT OF CLEAR SKIES...EXPECT TO SEE A BACK DOOR COLD FRONT
TO SLIP DOWN THE LAKE ON SATURDAY MORNING. ALONG WITH A DROP IN
TEMPERATURES...CLOUD COVERAGE MAY INCREASE. AT THIS POINT ITS TOUGH
TO SAY HOW WIDESPREAD THE CLOUDS WILL BE. MOST GUIDANCE KEEPS THE RH
FAIRLY LOW TOMORROW MORNING...HOWEVER BACK DOOR COLD FRONTS THIS
TIME OF YEAR CAN BRING LOW CLOUDS WITH THEM.

&&

.AVIATION/18Z TAFS/...

PRIMARY POINTS OF CONCERN ARE THE LAKE BREEZE THIS AFTERNOON AND A
BACK DOOR COLD FRONT THAT WILL SLIP DOWN THE LAKE ON SATURDAY
MORNING. THIS AFTERNOON...MUCH OF THE HIGH RES GUIDANCE HAS THE LAKE
BREEZE MAKING IT WELL INLAND...TO APPROX A FOND DU LAC TO DELEVAN
LINE...BEFORE WASHING OUT AROUND 00Z. HOWEVER...THERE IS SOME
UNCERTAINTY IN HOW FAR THE LAKE BREEZE GETS...AND THEREFORE THE
EXACT TIMING OF WHEN THE LAKE BREEZE REACHES THE TAF SITES IS NOT
CERTAIN. SATURDAY MORNING...THE BACK DOOR COLD FRONT SHOULD SWING
THE WINDS AROUND TO THE NORTH AT THE TAF SITES AROUND 09Z. MOST
GUIDANCE KEEPS THE RH FAIRLY LOW TOMORROW MORNING...HOWEVER BACK
DOOR COLD FRONTS THIS TIME OF YEAR CAN BRING LOW CLOUDS WITH THEM SO
THERE IS A POTENTIAL FOR SOME LOW CIGS AT THE LAKESHORE SITES.
AGAIN...THE EXACT TIMING IS UNCERTAIN...AND AT THIS POINT ITS TOUGH
TO SAY IF WE GET CLOUDS. IF WE DO CLOUD UP...LOW CIGS ARE
POSSIBLE.

&&

.PREV DISCUSSION... /ISSUED 330 PM CDT FRI APR 17 2015/

SHORT TERM...

SATURDAY NIGHT AND SUNDAY...FORECAST CONFIDENCE

SATURDAY NIGHT LOOKS TO BE QUIET UNTIL AN AREA OF LOW PRESSURE
SWINGS THROUGH THE UPPER MIDWEST STATES. LARGE SCALE JET STREAK OF
[] KTS WILL SUPPORT UPPER LEVEL DIVERGENT FLOW OVER THE REGION.
ALSO...A 500MB SHORTWAVE TROUGH WILL WITH ISENTROPIC OMEGA OF []
UBAR/S WILL ALSO SUPPORT PRECIPITATION. 12Z NAM IS GOING DRY FOR OUR
FORECAST AREA EXCEPT FOR OUR WESTERN COUNTIES...FROM MADISON AND
POINTS WEST. WHAT ABOUT THE ECMWF AND GFS?

A SECOND AREA OF LOW PRESSURE WILL MOVE INTO THE REGION FROM THE
SOUTHERN PLAINS. A BAND OF FRONTOGENETICAL FORCING ALONG WITH A
SHEARED RIBBON OF POSIVITVE VORITICITY ADVECTION AT THE 500 MB LEVEL
WILL RAMP UP RAIN CHANCES SUNDAY AFTERNOON...ALONG WITH CHANCES OF
THUNDERSTORMS AS MODEL SOUNDINGS INDICATE ELEVEATED INSTABILITY OF
NEARLY 100 J/KG. MODEL FORECAST SOUNDINGS ALSO INDICATE APPRECIABLE
MOISTENING OF THE LOW LEVELS AS THIS SSYTEM MOVES THROUGH.

LONG TERM...

MONDAY AND TUESDAY...FORECAST CONFIDENCE

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 GFS
AND ECMWF SHOW WHAT?

AS THE LOW PRESSURE MOVES OFF TO THE NORTHEAST...WINDS WILL VEER
FROM THE NORTHWEST AND INTENSIFY. THIS WILL SUPPORT COLD AIR
ADVECTION AND BRING IN 925MB TEMPERATURES OF []. THESE COOLER
TEMPERATURES WILL PERSIST FOR THE REST OF THE WEEK...AS LOWS WILL BE
IN THE [] TUESDAY THROUGH FRIDAY.

CHANCES OF RAIN PERSIST THROUGH TUESDAY?

TUESDAY NIGHT THROUGH FRIDAY...FORECAST CONFIDENCE

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. ON THE OTHER HAND...THE ECMWF IS KEEPING
CONDITIONS DRY FOR WEDNESDAY. CHANCES OF RAIN/SNOW MIX WEDNESDAY
MORNING.

THURSDAY LOOKS TO BE DRY...WHILE THE GFS BRINGS ANOTHER SYSTEM WITH
A BAND OF PRECIPITATION FRIDAY MORNING. THE ECMWF IS GOING DRY
DURING THIS SAME TIME PERIOD.

AVIATION/00Z TAFS/...

&&

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

$$

UPDATE...BSH
TODAY/TONIGHT AND AVIATION/MARINE...99
SATURDAY THROUGH THURSDAY...99


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