Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 290332
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1032 PM CDT THU APR 28 2016

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND FRIDAY
ISSUED AT 231 PM CDT THU APR 28 2016

THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW UPPER LEVEL
LOW PRESSURE SPINNING OVER THE IOWA/MINNESOTA BORDER EARLY THIS
AFTERNOON.  WEAK SHORTWAVE ROTATING AROUND THE UPPER LOW BROUGHT AN
AREA OF LIGHT RAIN TO MUCH OF CENTRAL AND EAST-CENTRAL WI TODAY.
ALSO RECEIVED A FEW REPORTS OF SLEET MIXING IN WITH THE SHOWER
ACTIVITY.  MEANWHILE...NORTHERN WI HAS REMAINED DRY SO FAR DUE TO
ITS CLOSER PROXIMITY TO A VERY DRY HUDSON BAY HIGH PRESSURE SYSTEM.
AS THE UPPER LOW MOVES EAST ACROSS THE STATE TONIGHT...RAIN TRENDS
ARE THE MAIN FORECAST CONCERN.

TONIGHT...THE UPPER LOW PRESSURE WILL BE MOVING ACROSS THE STATE OF
WISCONSIN TONIGHT.  THE CHANCE OF SHOWERS WILL THEREFORE CONTINUE
OVER MAINLY CENTRAL AND EAST-CENTRAL WISCONSIN WHERE MID-LEVEL
CONVERGENCE WILL BE OCCURRING.  ACROSS NORTHERN WISCONSIN...EAST
WINDS WILL CONTINUE TO FUNNEL IN VERY DRY AIR PER APX 12Z SOUNDING.
ALTHOUGH SOME MESO MODELS TRY TO DEVELOP PRECIP OVER N-C
WISCONSIN...THIS LOOKS OVERLY AMBITIOUS AND WILL MAINTAIN A DRY
FORECAST.  CHANCES OF PRECIP LOOK TO END LATE TONIGHT WHEN THE UPPER
LOW MOVES INTO CENTRAL LAKE MICHIGAN. LOWS MAINLY IN THE 30S.

FRIDAY...DESPITE THE UPPER LOW PULLING AWAY FROM THE REGION TO THE
EAST...AMPLE CLOUD COVER SHOULD LINGER THROUGH THE MORNING HOURS
OVER CENTRAL TO NORTHEAST WISCONSIN.  ONLY NORTH-CENTRAL WI WILL
HAVE A CHANCE TO START OUT WITH SOME SUNSHINE.  CLOUDS LOOK TO
PARTIALLY CLEAR OVER CENTRAL AND NORTHEAST WI FROM LATE MORNING INTO
THE MID-AFTERNOON HOURS.  BUT CU IS LIKELY TO REDEVELOP WITH ANY
HEATING.  HIGHS RETURNING INTO THE MIDDLE 50S.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY
ISSUED AT 231 PM CDT THU APR 28 2016

SHORTWAVE RIDGING TO START THE EXTENDED PERIOD FRIDAY NIGHT WILL
EVENTUALLY PINCH OFF AS A MID LEVEL LOW PRESSURE SYSTEM ACROSS THE
PLAINS AND SHORTWAVE TROUGH TRACKING THROUGH SOUTHERN CANADA
COMBINE INTO ONE LARGE TROUGH WITH A SURFACE LOW TRACKING THROUGH
THE OHIO VALLEY DURING THE WEEKEND. DRY NORTHERLY FLOW FROM CANADA
WILL HELP TO KEEP MUCH OF THE RAIN FROM THIS SYSTEM SOUTH OF THE
AREA...HOWEVER SOME RAIN COULD GET INTO THE SOUTHERN CWA SATURDAY
AFTERNOON AND SATURDAY NIGHT. MODEL SOUNDINGS SHOW MOISTURE IS
FAIRLY LIMITED WITH WEAK ISENTROPIC LIFT AS THIS SYSTEM TRACKS TO
OUR SOUTH...THEREFORE POPS WILL REMAIN FAIRLY LOW DURING THIS
EVENT. THE CLOUDS AND NORTHERLY FLOW WILL KEEP TEMPERATURES RIGHT
AROUND OR BELOW NORMAL FOR THIS TIME OF YEAR DURING THE WEEKEND.

AFTER THE WEEKEND THE FORECAST PICTURE BECOMES A BIT MORE MUDDLED.
THE AREA REMAINS IN A LARGE SCALE TROUGH...WITH SEVERAL PV
ANOMALIES ROUNDING THE TROUGH AT TIMES AND TRACKING THROUGH THE
WESTERN GREAT LAKES. THE TIMING OF THESE FEATURES HAS PROVEN
PROBLEMATIC...AS THE NWP MODELS DIFFER ON THE TIMING AND STRENGTH
OF THESE FEATURES AS THE TRACK THROUGH THE AREA. THEREFORE
PRECIPITATION TIMING IN THE EARLY TO MIDDLE PART OF NEXT WEEK
REMAINS TENUOUS AT BEST...WITH LOW CONFIDENCE IN ANY PERIOD OF
RAIN FALLING. HOWEVER THERE IS MEDIUM CONFIDENCE THAT THESE
TROUGHS WILL PRODUCE RAIN AT TIMES NEXT WEEK...BUT THE TIMING IS
UNCERTAIN. THEREFORE WITHOUT ANY CLEAR SIGNAL THAT FAR OUT WILL GO
WITH THE MODEL BLEND FOR POPS AND ADJUST ACCORDINGLY IN FUTURE
FORECASTS.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1031 PM CDT THU APR 28 2016

SPRINKLES/INTERMITTENT LGT RAIN CONTD ACRS THE SRN PART OF THE
AREA. CIGS WERE GENERALLY STILL IN THE VFR CATEGORY...THOUGH HAD
EDGED DOWN A BIT IN CENTRAL WI. THE PCPN WL GRADUALLY DECR AND
END AS THE SYSTEM PRODUCING THE RAIN SHIFTS OFF TO THE E. CIGS WL
GRADUALLY LIFT TOMORROW...AND CLEARING WL WORK SWWD ACRS THE AREA.
&&

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

$$

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



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