Area Forecast Discussion
Issued by NWS Green Bay, WI

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537
FXUS63 KGRB 051047
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
547 AM CDT THU MAY 5 2016

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND FRIDAY
ISSUED AT 304 AM CDT THU MAY 5 2016

AFTER A MORNING WITH COOL TEMPERATURES AND FROST ACROSS CENTRAL
WISCONSIN...TEMPERATURES WILL REBOUND QUICKLY ACROSS NORTHEAST
WISCONSIN UNDER STRONG WARM AIR ADVECTION. HIGHS TODAY ARE
EXPECTED TO SOAR INTO THE LOWER TO MIDDLE 60S AWAY FROM THE
LAKESHORE...WITH MIDDLE TO UPPER 50S NEAR LAKE MICHIGAN AND THE
BAY OF GREEN BAY WITH THE COOLER WATER HOLDING DOWN TEMPERATURES.
FAIRLY LOW SURFACE DEW POINTS WILL CAUSE AFTERNOON RELATIVE
HUMIDITY VALUES TO FALL INTO THE 20 TO 35 PERCENT RANGE ACROSS
CENTRAL AND NORTH CENTRAL WISCONSIN.

MODELS ARE PERSISTENT IN GENERATING QPF TONIGHT DESPITE A RIDGE IN
PLACE ACROSS THE WESTERN GREAT LAKES REGION. CLOSER INSPECTION
SHOWS MID AND LOW LEVEL MOISTURE INCREASING TONIGHT WITH WEAK BUT
NOTICEABLE ISENTROPIC LIFT AS WINDS BECOME PERPENDICULAR TO THE
ISENTROPIC SURFACE DURING THE OVERNIGHT HOURS. THE MOISTURE AND
LIFT BEING MEAGER WILL MEAN POPS WILL STAY SLIGHT CHANCE...IN THE
20 PERCENT RANGE...PER THE PREVIOUS FORECAST.

FRIDAY WILL BE EVEN WARMER THAN TODAY AS CONTINUED WARM AIR
ADVECTION AHEAD OF AN APPROACHING WARM FRONT LIFTS 850 MB
TEMPERATURES INTO THE MIDDLE TEENS. THIS WILL CAUSE AFTERNOON
HIGHS ON FRIDAY TO SOAR TO 80 TO 85 DEGREES AWAY FROM THE
LAKESHORE. DEEP MIXING WILL KEEP DEW POINTS RELATIVELY LOW ON
FRIDAY...AS AFTERNOON RELATIVE HUMIDITY VALUES ONCE AGAIN DROP
INTO THE 20 TO 35 PERCENT RANGE. DESPITE AN APPROACHING COLD FRONT
FRIDAY IS EXPECTED TO BE DRY AS THE FRONT ITSELF WILL ONLY MAKE IT
INTO NORTHWEST WISCONSIN BY LATE AFTERNOON.

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 304 AM CDT THU MAY 5 2016

THE LATEST MEDIUM RANGE MODELS REMAIN IN GOOD AGREEMENT THROUGH THE
WEEKEND...THEN DIVERGE WHEN AN UPPER LEVEL LOW MOVES ACROSS THE
CENTRAL PLAINS EARLY NEXT WEEK.  THE FIRST FORECAST CONCERN FOR THIS
PERIOD IS PRECIP POTENTIAL FRIDAY NIGHT INTO EARLY SATURDAY ALONG A
COLD FRONT.  SOME SLIGHT TIMING DIFFERENCES LINGER IN REGARDS TO
THIS FRONT...AND PREFER A ECMWF/NAM BLEND WHICH HAS MORE SUPPORT
FROM OTHER GUIDANCE.  FOR LATER PERIODS...A ECWMF/GFS ENSEMBLE MEAN
BLEND SHOULD WORK.

FRIDAY NIGHT THRU SATURDAY NIGHT...A STRONG SHORTWAVE WILL BE
DIGGING SOUTHEAST AND PUSHING A COLD FRONT SOUTH ACROSS THE REGION
FRIDAY NIGHT.  MODERATE MID-LEVEL FGEN WILL EXIST BEHIND THE SURFACE
FRONT WHILE MID-LEVEL LAPSE RATES OF 6.5-7.5 C/KM WILL PREVAIL AHEAD
OF THE BOUNDARY.  PROGGED SOUNDINGS REVEAL MORE MID-LEVEL MOISTURE
THAN THE PAST COUPLE NIGHTS...WHICH YIELDS MU CAPES OF AROUND 1000
J/KG. ON THE DOWNSIDE...EFFECTIVE SHEARS ARE LESS THAN 20 KTS AND
THE FRONT WILL RESIDE IN THE RIGHT FRONT QUAD OF A JET STREAK...AN
UNFAVORABLE POSITION FOR UPPER DIVERGENCE.  AS A RESULT...THE
SIGNIFICANT SEVERE PARAMETER PEAKS UPSTREAM OVER NORTHERN
MINNESOTA...THEN DIMINISHES RELATIVELY RAPIDLY FRIDAY EVENING AS THE
FRONT MOVES INTO NORTH-CENTRAL WI.  THEREFORE THINK THAT ANY SEVERE
THREAT REMAINS LOW.  TIMING OF THE FRONT WILL BE BETWEEN 03Z-12Z
SATURDAY...WHEN THE BEST CHANCE OF SHOWERS AND STORMS WILL OCCUR.
CHANCES FOR PRECIP WILL REMAIN IN THE LOW CHANCE RANGE...DUE TO
UNCERTAINTY WITH AVAILABLE INSTABILITY AND MOISTURE.

TEMPERATURES WILL REMAIN MILD AHEAD OF THE FRONT ON FRIDAY
NIGHT...THEN COOL OFF BACK TO SEASONABLE LEVELS BEHIND THE FRONT FOR
SATURDAY.  ANY LINGERING CLOUD COVER/PRECIP SHOULD EXIT EARLY ON
SATURDAY...THEN SHOULD SEE MOSTLY CLEAR SKIES FOR THE REST OF
SATURDAY AND SATURDAY NIGHT.

REST OF THE FORECAST...CONDITIONS WILL REMAIN SEASONABLE AND QUIET
ON SUNDAY.  THEN A SMALL CHANCE OF RAIN WILL RETURN ON MONDAY WHEN
LOW PRESSURE MOVES INTO THE CENTRAL PLAINS.  AS PRECIP MOVES
NORTH...IT WILL RUN INTO AMPLE DRY AIR ACROSS THE REGION...SO BEST
CHANCES WILL RESIDE OVER CENTRAL AND EAST-CENTRAL WI.  THE WEATHER
WILL REMAIN UNSETTLED TUE-THU AS THE UPPER LOW MEANDERS TOWARDS THE
REGION.  DESPITE THE POTENTIAL FOR RAIN...TEMPERATURES WILL REMAIN
SEASONABLE THRU THU.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 547 AM CDT THU MAY 5 2016

SOME MVFR AND LIFR VSBYS ARE POSSIBLE AT RHI FOR THE FIRST FEW
HOURS OF THE TAF CYCLE AS LIGHT WINDS AND CLEAR SKIES HAVE LED TO
SOME GROUND FOG. OTHERWISE VFR CONDITIONS ARE EXPECTED TODAY AND
TONIGHT AS A SURFACE HIGH PRESSURE BUILDS INTO THE WESTERN GREAT
LAKES. SOME MID AND HIGH LEVEL CLOUDS ARE POSSIBLE AT TIMES FROM
UPSTREAM ACTIVITY.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
FROST ADVISORY UNTIL 7 AM CDT THIS MORNING FOR WIZ020-030-031-
035>037-045.
&&

$$

SHORT TERM.....KURIMSKI
LONG TERM......MPC
AVIATION.......KURIMSKI



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