Area Forecast Discussion
Issued by NWS Green Bay, WI

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873
FXUS63 KGRB 180436
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1136 PM CDT SUN MAY 17 2015

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.UPDATE...
ISSUED AT 608 PM CDT SUN MAY 17 2015

STORMS HAVE DIMINISHED IN INTENSITY AND COVERAGE THE
LAST FEW HOURS OVER THE FORECAST AREA. MESO DATA SUGGESTS THE
REGION OF POTENTIAL NEW DEVELOPMENT OF STORMS LIKELY OVER THE
NORTHWEST HALF OF THE STATE...INCLUDING PARTS OF CENTRAL AND
NORTH CENTRAL WISCONSIN WITH THE BEST SHEAR VALUES...AND STEEP
SURFACE LAPSE RATES. ANTICIPATE THE SURFACE LAPSE RATES TO BE ON
THE DECLINE THE NEXT FEW HOURS...SO THE THREAT OF STRONG TO SEVERE
STORMS SHOULD LESSON. SPIRALING BANDS OF CONVECTION OVER EASTERN
MINNESOTA AND FAR WESTERN WISCONSIN CLOSER TO THE LOW PRESSURE
AREA OVER NORTHERN MINNESOTA MAY ROTATE INTO THIS ENVIRONMENT AND
INTENSIFY OVER NORTH CENTRAL WISCONSIN THIS EVENING.
&&

.SHORT TERM...TONIGHT AND MONDAY
ISSUED AT 229 PM CDT SUN MAY 17 2015

THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW AN OCCLUDED
LOW PRESSURE SYSTEM SPINNING OVER THE EASTERN DAKOTAS.  SHORTWAVES
ARE ROTATING NORTHWARD AHEAD OF THIS OCCLUDED CYCLONE...THE
STRONGEST OF WHICH IS LOCATED OVER EASTERN IOWA.  A PWAT AXIS IS
MOVING ACROSS WISCONSIN EARLY THIS AFTERNOON...WHICH COMBINED WITH
MOISTURE CONVERGENCE...IS CONTRIBUTING TO SCATTERED SHOWER
DEVELOPMENT OVER CENTRAL WISCONSIN.  CLOUD COVER HAS SIGNIFICANTLY
SLOWED THE HEATING CURVE SO FAR TODAY...KEEPING ML CAPES BELOW 200
J/KG.  WITH SHOWER COVERAGE EXPECT TO INCREASE THROUGH THE
AFTERNOON...IT WILL BE TOUGH TO SEE MUCH OF AN INCREASE OF
INSTABILITY.  STILL THOUGH...RADAR ECHOES SUGGEST SOME THUNDERSTORMS
WILL BE POSSIBLE...AND ANY STORMS COULD BRING DOWN STRONG WINDS FROM
ALOFT.  WILL HAVE TO KEEP A MENTION OF ISOLATED DAMAGING WINDS
THROUGH EARLY THIS EVENING. OTHERWISE...THE LATEST HRRR CONGEALS THE
SHOWER ACTIVITY INTO BAND AND PROGRESSES IT ACROSS THE FORECAST AREA
FOR THE REST OF THE AFTERNOON.

TONIGHT...LOW PRESSURE WILL MOVE EAST ACROSS NORTHERN
MINNESOTA...WHILE A COLD FRONT WILL PUSH EAST THROUGH ALL BUT FAR
EASTERN WISCONSIN OVERNIGHT.  THOUGH SHORTWAVE ENERGY WILL BE
ROTATING NORTHEAST OVER NORTHWEST WISCONSIN THROUGH THE
EVENING...CONCERNED THAT STRONG DRYING AND INCREASING CAPPING IN THE
MID-LEVELS WILL EVEN FURTHER LIMIT THUNDERSTORM POTENTIAL FOR THE
FIRST COUPLE HOURS IN THE EVENING.  WILL KEEP A MENTION OF ISOLATED
DAMAGING WINDS THROUGH 02Z IN CASE SOME THUNDERSTORMS MAKE A RUN
INTO N-C WISCONSIN FROM MINNESOTA.  ONCE THE THREAT OF STORMS ENDS...MODELS
SHOW CLEARING TAKING PLACE UNTIL LOW CLOUDS FLOOD EAST BEHIND THE
COLD FRONT LATE TONIGHT.  LOW TEMPS NEAR 60 OVER THE EAST...BUT
COOLING TO NEAR 50 OVER THE WEST.

MONDAY...OCCLUDED LOW PRESSURE WILL BE WEAKENING AS IT MOVES TO THE
EAST ACROSS LAKE SUPERIOR.  WEST WINDS ON THE SOUTHERN FLANK OF THE
LOW WILL BE COLD ADVECTING THROUGH THE DAY...WHILE PUSHING IN WRAP
AROUND MOISTURE.  SHOULD SEE AMPLE CLOUD COVER OVER CENTRAL AND
NORTH-CENTRAL WISCONSIN THROUGH THE DAY...BUT EAST-CENTRAL WISCONSIN
WILL LIKELY SEE SOME SUN IN THE MORNING BEFORE CLOUDS INCREASE IN
THE AFTERNOON.  WITH THE SUNSHINE...TEMPS SHOULD WARM TO NEAR 70 IN
THE EAST...BUT ONLY INTO THE MID AND UPPER 50S OVER THE WEST.

.LONG TERM...MONDAY NIGHT THROUGH SUNDAY
ISSUED AT 229 PM CDT SUN MAY 17 2015

MUCH COOLER TEMPERATURES FOR THE FIRST HALF OF THE WORK WEEK...DRY
AND MILDER CONDITIONS FOR THE LATTER HALF...AND A POSSIBLE RETURN
TO WET WEATHER LATER IN THE MEMORIAL DAY WEEKEND...ARE THE MAIN
FCST CONCERNS.

THE REMNANTS OF THE UPPER LOW WILL TRACK ACROSS NORTHERN LAKE SUPERIOR
ON MONDAY NIGHT...FOLLOWED BY A S/W TROF PASSING NORTH OF WI ON TUESDAY.
UNSEASONABLY COLD AIR (H8 TEMPS -8 TO -10 C) WILL FLOW INTO THE REGION
ON NNW WINDS...SETTING THE STAGE FOR SOME LAKE-ENHANCED SHOWERS OVER
NC WI. LOW-LEVEL TEMPS AND THICKNESSES SUPPORT A MIX THEN CHANGEOVER
TO SNOW LATE MONDAY NIGHT INTO TUESDAY MORNING...WITH LITTLE OR NO
ACCUMULATION EXPECTED. ANY LINGERING PCPN SHOULD END TUESDAY AFTERNOON
AS CANADIAN HIGH PRESSURE BUILDS INTO THE REGION.

HIGH PRESSURE WILL COVER THE AREA TUESDAY NIGHT INTO WEDNESDAY. STILL
EXPECTING FROST TUESDAY NIGHT...BUT GETTING A LITTLE CONCERNED ABOUT
THE POSSIBILITY OF THICKER HIGH LEVEL CLOUDS...DUE TO THE PRESENCE
OF A STRONG JET STREAK OVER THE REGION. RIGHT NOW...HAVE JUST
BUMPED UP CLOUD COVER A BIT OVER C/EC WI...BUT KEPT MOSTLY CLEAR
SKIES OVER NORTHERN WI. WILL CONTINUE TO CARRY WIDESPREAD FROST OR
FREEZE CONDITIONS OVER NORTHERN WI...AND PATCHY FROST OVER MOST OF
C/EC WI.

A WEAK BACK DOOR COLD FRONT WILL SAG THROUGH THE FORECAST AREA THURSDAY
INTO THURSDAY NIGHT...BUT WILL NOT HAVE ANY MOISTURE TO WORK WITH...SO
DRY WEATHER WILL PREVAIL. BEHIND THE FRONT...CANADIAN HIGH PRESSURE
WILL REESTABLISH ITSELF OVER THE WESTERN GREAT LAKES...AND IS EXPECTED
TO LINGER INTO SATURDAY. ABUNDANT SUNSHINE SHOULD BRING A RETURN TO
NEAR NORMAL TEMPERATURES FOR THE LATTER HALF OF THE WEEK.

AN UPPER TROF...LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT WILL
IMPACT THE REGION FROM SATURDAY NIGHT INTO SUNDAY. GULF MOISTURE
IS EXPECTED TO FLOW INTO THE REGION AHEAD OF THE FRONT...WITH
PRECIPITABLE WATER VALUES REACHING 1.00-1.25 INCHES. HAVE RAMPED
POPS UP TO LIKELY FOR SUNDAY. THE ECMWF PULLS MOST OF THE PCPN OUT
OF THE REGION SUNDAY EVG...WHILE THE GFS HANGS ONTO SIGNIFICANT
QPF INTO MEMORIAL DAY...SO FCST CONFIDENCE WANES BEYOND SUNDAY.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1135 PM CDT SUN MAY 17 2015

LAST OF THE SHOWERS WERE DEPARTING FAR NORTH CENTRAL
WISCONSIN LATE THIS EVENING. OTHERWISE VFR CONDITIONS TO PREVAIL
OVERNIGHT ALONG WITH LLWS CONDITIONS. LLWS CONDITIONS WILL END
MONDAY MORNING BUT BLUSTERY WEST SURFACE WINDS WILL DEVELOP.
WRAP AROUND MVFR CIGS DUE TO THE DEPARTING UPPER LOW SYSTEM WILL
BEGIN TO WORK INTO CENTRAL AND NORTH CENTRAL WISCONSIN MONDAY
MORNING. CIGS WILL CONTINUE TO WORK INTO EASTERN AREAS BUT WILL
MORE OF THE LOWER END VFR CIGS.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE.........TDH
SHORT TERM.....MPC
LONG TERM......KIECKBUSCH
AVIATION.......TDH






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