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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI
317 AM CDT SUN APR 26 2015

.SHORT TERM...

TODAY AND TONIGHT...FORECAST CONFIDENCE IS HIGH. 

AN UPPER LEVEL TROUGH ACROSS FAR SOUTHEAST CANADA EXTENDS BACK INTO 
THE UPPER GREAT LAKES.  THIS TROUGH DROPS SOUTH A LITTLE AND BUILDS 
BACK INTO WISCONSIN THIS EVENING. LITTLE IN THE WAY OF UPPER 
DIVERGENCE OR 700 MB UPWARD MOTION.  THERE IS SOME INCREASE IN 700 
MB RH THIS AFTERNOON FROM THE EAST THAT REACHES THE LAKE MICHIGAN 
COUNTIES.  850 MB RH ALSO INCREASES...BUT MAINLY LATER TONIGHT. 
HOWEVER IT IS NOT SATURATED...SO DO NOT EXPECT ANY EXTENSIVE CLOUD 
SHIELD.  

THE MAIN CONCERN IS THE INCREASE IN 700 MB WINDS THIS AFTERNOON... 
AND THE 850 MB WINDS MAINLY TONIGHT.  WHILE THE 700 MB WIND INCREASE 
OCCURS ACROSS SOUTHERN WISCONSIN THE 850 MB WIND INCREASE IS MAINLY 
NEAR LAKE MICHIGAN.  WITH SURFACE HEATING WIND GUSTS...WHILE NOT 
STRONG...WILL LIKELY BE STRONGER THAN THE WEAK SURFACE PRESSURE 
GRADIENT SUGGESTS. 
 
WITH THE NORTHEAST WINDS OFF LAKE MICHIGAN...EXPECT TYPICAL 
SPRINGTIME COOLING NEAR LAKE MICHIGAN...WITH MILD TEMPERATURES WELL 
INLAND. 

.LONG TERM...

MONDAY THROUGH THURSDAY... FORECAST CONFIDENCE HIGH.

DRY AIR AND MID LEVEL RIDGING WILL NOSE INTO THE WESTERN GREAT LAKES 
EARLY THIS WEEK AS A SPRAWLING CLOSED UPPER LOW OVER NEW ENGLAND 
SHIFTS EAST. SURFACE HIGH PRESSURE WILL TAKE HOLD OF THE UPPER 
MIDWEST AND GREAT LAKES THROUGH THURSDAY AND BRING A PLEASANT 
STRETCH OF WEATHER TO SOUTHERN WI. THERE WILL BE A STEADY BREEZE OUT 
OF THE NORTH THROUGH THIS PERIOD... BUT WITH THE WEAK PRESSURE 
GRADIENT WE CAN EXPECT A LAKE BREEZE TO DEVELOP EACH DAY. INLAND 
TEMPS WILL BE IN THE 60S FOR THIS PERIOD WHILE LAKESHORE TEMPS WILL 
BE STUCK IN THE 50S. 

A MID LEVEL SHORTWAVE WILL DROP DOWN THROUGH WI TUE AFTERNOON/ 
EVENING. BOTH THE ECMWF AND GFS MODELS NOW HAVE A DRY FORECAST FOR 
TUE NIGHT AND WEDNESDAY. THIS UPPER TROUGH WILL BRING AT LEAST A MID 
LEVEL CLOUD DECK... WITH THE POSSIBILITY OF SOME SPRINKLES.

FRIDAY THROUGH SUNDAY... FORECAST CONFIDENCE MEDIUM.

ANOTHER SHORTWAVE TROUGH CROSSING THE NORTHERN PLAINS WILL BRING OUR 
NEXT CHANCE FOR RAIN FRIDAY NIGHT. THUNDER IS DEBATABLE. THERE MAY 
BE SOME WEAK ELEVATED INSTABILITY TO SUPPORT ISOLATED THUNDER. LEFT 
IT OUT OF THE FORECAST UNTIL THERE IS MORE CERTAINTY.

THE GFS AND ECMWF TAKE ON SLIGHTLY DIFFERENT UPPER LEVEL WEATHER 
PATTERNS LATER NEXT WEEKEND... BUT BOTH RESULT IN PRECIP CHANCES 
SATURDAY NIGHT INTO SUNDAY. THE GFS KEEPS TEMPERATURES SLIGHTLY 
COOLER THAN THE ECMWF DUE TO A NORTHWEST FLOW PATTERN.

&&

.AVIATION/12Z TAFS/...

EXPECTING VFR CONDITIONS THROUGH THE FORECAST. COULD SEE SOME 
DIURNAL CUMULUS THIS AFTERNOON...ESPECIALLY OVER EASTERN PORTIONS OF 
THE FORECAST AREA AWAY FROM THE MORE STABLE EFFECTS NEAR LAKE 
MICHIGAN.  SOME CLOUDS IN THE 5 TO 8 THSD FT RANGE MAY AFFECT THE 
SOUTHEAST LATER THIS AFTERNOON AND TONIGHT FROM A WEAK TROUGH AXIS 
ROTATING AROUND THE BACK SIDE OF ELONGATED UPPER TROUGH CENTERED 
OVER THE CANADIAN MARITIMES.  DRY AIR IN PLACE SHOULD LIMIT COVERAGE 
TO MAINLY SCATTERED.

NORTHEAST WIND GUSTS WILL INCREASE AGAIN WITH MIXING BUT WITHOUT THE 
GUSTS LIKE SATURDAY. 

&&

.MARINE...

WINDS ARE EASING TO BELOW SMALL CRAFT ADVISORY CRITERIA THIS 
MORNING. A SURGE IN STRONGER NORTH/NORTHEAST WINDS LATER THIS 
AFTERNOON AND TONIGHT COULD PUSH WINDS AND WAVES BACK TOWARDS SMALL 
CRAFT LEVELS. 

&&

.FIRE WEATHER...

MIN RH VALUES WILL DROP TO AROUND 25 PCT WELL INLAND AND ESPECIALLY 
OVER SOUTH CENTRAL WISCONSIN...MAYBE DOWN TOWARDS 20 PCT.   

THE MAIN CONCERN IS THE INCREASE IN 700 MB WINDS THIS AFTERNOON... 
AND THE 850 MB WINDS MAINLY TONIGHT.  WHILE THE 700 MB WIND INCREASE 
OCCURS ACROSS SOUTHERN WISCONSIN THE 850 MB WIND INCREASE IS MAINLY 
NEAR LAKE MICHIGAN.  WITH SURFACE HEATING WIND GUSTS...WHILE NOT 
STRONG...WILL LIKELY BE STRONGER THAN THE WEAK SURFACE PRESSURE 
GRADIENT SUGGESTS. 

&&

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

$$

TODAY/TONIGHT AND AVIATION/MARINE...HENTZ
MONDAY THROUGH SATURDAY...MRC

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