Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 132026
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
326 PM CDT SUN APR 13 2014

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND MONDAY
ISSUED AT 325 PM CDT SUN APR 13 2014

FORECAST CONCERNS AGAIN ON PCPN TYPE AND AMOUNTS. SHORT WAVE OVER
CENTRAL PLAINS LIFTING NORTHEAST...TO PASS THROUGH STATE LATE
TONIGHT. SURFACE WARM FRONT OVER NORTHERN IL AT 19Z WITH
TIGHTENING 850 BAROCLINIC ZONE OVER STATE. CONVECTION ATTM TIED TO
SURFACE FRONT AND SOUTH WHERE LLVJ FOCUSED.

LARGE AREA OF PCPN SLOWLY MAKING ITS WAY NORTH THROUGH SOUTHERN
WI...INCREASING RETURNS ALSO SEEN OVER NORTHWEST PORTION OF
STATE WHERE MODELS INDICATE INCREASING FGEN FORCING. SOME QUESTION
ON WHEN PCPN WILL CHANGE OVER. SURFACE TEMPS/DEW POINTS WARMER
THAN WHAT MODELS WOULD INDICATE. HAVE STAYED WITH A 0Z TO 3Z
PERIOD FOR NORTHWEST...AND 6 TO 9Z PERIOD SOUTHEAST. CONCERNS ON
SNOW AMOUNTS...WITH NAM SUGGESTING ADVISORY LEVEL GIVEN STRONG
DYNAMICS...THOUGH SNOW GROWTH REGION IS LIMITED. HAVE GONE WITH A
1 TO 3 INCH AMOUNT OVER THE CWA.  LATER SHIFT WILL NEED TO MONITOR.

MAIN TROF PASSES THROUGH MONDAY...ENDING PCPN FOR THE AFTN...WITH
BREEZY COOL CONDITIONS EXPECTED REMAINDER OF DAY.

.LONG TERM...MONDAY NIGHT THROUGH SUNDAY
ISSUED AT 325 PM CDT SUN APR 13 2014

TRANSITIONAL AND PROGRESSIVE PATTERN NEXT FEW DAYS AS UPPER FLOW
GOES FROM NW TO ZONAL THEN MORE SW AS ENERGY APPROACHES FROM THE
PLAINS. WHAT THIS MEANS IS SEVERAL CHANCES FOR PRECIPITATION.
WITH COLDER THAN NORMAL TEMPS THRU MUCH OF PERIOD...SOME OF THAT
MAY FALL AS SNOW...ESPECIALLY ACROSS THE NORTH.

AT THE START OF THE PERIOD TEMPERATURES ARE EXPECTED TO BE MUCH
BELOW NORMAL FOR THIS TIME OF YEAR IN NORTHWEST FLOW ALOFT. THERE
WILL BE A MODERATION AS UPPER FLOW BACKS AND BECOMES MORE ZONAL
AND THEN SOUTHWEST.

SUBTLE SHORTWV RIDGING AND SURFACE HIGH BRINGS ONE DECENT WEATHER
DAY THIS WEEK ON TUESDAY...THOUGH TEMPS WILL BE AROUND 15 DEG
COLDER THAN NORM.

FIRST ROUND OF PRECIP DURING THIS PERIOD APPROACHES WED AS UPPER
SHORTWV ENERGY AND SURFACE REFLECTION/FRONT MOVES ESE TOWARD
STATE. FORECAST FOR THIS SYSTEM A BLEND OF 13/12Z MODELS WHICH IS
VERY CLOSE TO PREVIOUS FORECAST. HAVE INCREASED POPS GIVEN
SLIGHTLY BETTER MODEL AGREEMENT...WITH BEST CHANCE ACROSS THE
NORTH. COLD ENOUGH FOR SNOW/MIX...ESP AT NIGHT. AN INCH OR TWO NOT
OUT OF THE QUESTION IN THE NORTH.

ASSOCIATED SFC FRONTAL BOUNDARY HANGS UP ACROSS WESTERN GREAT
LAKES AND IS FOCUS FOR ADDITIONAL PRECIP AS SURFACE LOW DEVELOPS
AHEAD OF DEEPER UPPER WAVE MOVING OUT OF PLAINS. CONSIDERABLE
DIFFERENCES BETWEEN 13/12Z GFS AND ECMWF BY THE TIME THE SYSTEM
MOVES ACROSS STATE FRIDAY. WILL CONTINUE WITH HIGHEST POPS ON
FRIDAY WITH THIS SYSTEM AND MIX ACROSS THE NORTH AND MAINLY RAIN
IN THE SOUTH PART OF FORECAST AREA.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1251 PM CDT SUN APR 13 2014

BREAK IN PCPN AND SOME DRIER AIR MOVING IN ON NORTHERLY FLOW
LEADING TO SOME IMPROVEMENT IN CIGS AND VSBYS THIS
MORNING/AFTERNOON. THIS IS TEMPORARY AS NEXT WAVE OF PCPN HEADING
NORTH AND EAST OUT OF MN AND IA. IFR CIGS TO BECOME WIDESPREAD
AGAIN LATER TODAY/TONIGHT AS RAIN REDEVELOPS. IFR CONDITIONS WITH GUSTY
NORTH WINDS WILL DEVELOP TONIGHT WITH THE RAIN CHANGING TO SNOW
FROM NORTHWEST TO SOUTHEAST MID TO LATE EVENING. SNOW EXPECTED TO
EXIT REGION MON MORNING...THOUGH NOT BEFORE LEAVING A 1 TO 3 INCH
ACCUMULATION.
&&

.MARINE...
ISSUED AT 325 PM CDT SUN APR 13 2014

SMALL CRAFT ADVISORY IN EFFECT BUT POTENTIAL FOR SHORT
PERIOD OF GALE FORCE GUSTS POSSIBLE AFTER MIDNIGHT WITH STRONG
NORTH NORTHEAST WINDS AND PRESSURE COUPLET PASSING THROUGH.
LOCALIZED GALE GUSTS ALSO POSSIBLE THROUGH DEATHS DOOR AS WINDS
SHIFT TO NORTHWEST.
&&

.HYDROLOGY...
ISSUED AT 325 PM CDT SUN APR 13 2014

WILL LET FLOOD WATCH CONTINUE...FLASH FLOOD GUIDANCE IS VERY LOW
1 INCH/6 HOURS OVER MOST OF WATCH AREA. PCPN SLOWER IN MAKING
PROGRESS NORTH...SOMEWHAT DUE TO DRIER AIR ALOFT FOLLOWING
YESTERDAYS WAVE. MODELS CONTINUE TO SUGGEST QPF AMOUNTS OF 1 TO
1.5 INCHES WORKING NORTH INTO FLOOD WATCH AREA THIS EVENING AND
TONIGHT. CONVECTION TIED TO FRONT WHICH IS FURTHER SOUTH THAN
YESTERDAY...SO EXPECT HEAVY QPF TO BE MORE WIDESPREAD AND NOT AS
LOCALIZED.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
FLOOD WATCH THROUGH MONDAY MORNING FOR WIZ045-048>050.
&&

$$

SHORT TERM.....TE
LONG TERM......JKL
AVIATION.......TE
MARINE.........TE
HYDROLOGY......TE






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