Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 310843
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
343 AM CDT THU JUL 31 2014

FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND FRIDAY
ISSUED AT 343 AM CDT THU JUL 31 2014

PCPN TRENDS...FOG TRENDS AND TEMPERATURES ARE THE MAIN FCST
CONCERNS.

SHOWERS HAD ENDED OVER CENTRAL WI...AND MID-LEVEL CLOUDS WERE
GRADUALLY ERODING OVER THE SW PART OF THE FCST AREA. AREAS OF
FOG HAD DEVELOPED OVER NC WI...WITH PATCHY FOG REPORTED
ELSEWHERE. DENSE FOG WAS OCCURRING OVER PARTS OF VILAS...
ONEIDA AND LINCOLN COUNTIES.

VSBYS HAD ALREADY DROPPED TO 1/4SM-3/4SM OVER VILAS...ONEIDA AND
LINCOLN COUNTIES EARLY THIS MORNING...AND WILL LIKELY LOWER
SOME MORE OVER THE NEXT FEW HOURS. THIS SAME AREA HAD DENSE FOG
YESTERDAY MORNING. GIVEN THE POTENTIAL FOR HAZARDOUS DRIVING
CONDITIONS FOR THE MORNING COMMUTE...HAVE DECIDED TO ISSUE A
DENSE FOG ADVISORY THROUGH 8 AM.

ALTHOUGH SOME WEAK SHORT-WAVE ENERGY MAY MOVE THROUGH THE RGN
TODAY...NO SIGNIFICANT FORCING IS EXPECTED. DRIER CANADIAN
AIR...WITH PWATS AROUND 0.75 INCH...WILL MOVE INTO NORTHERN WI
TODAY...SO ANY CONVECTION THAT DEVELOPS SHOULD BE ISOLD/SCT.
MODIFIED FCST SOUNDINGS SUPPORT CAPE OF 500-1000 J/KG...WITH THE
BEST INSTABILITY OCCURRING OVER THE SW HALF OF THE CWA. LLVL
CONVERGENCE IS EXPECTED TO BE STRONGEST OVER FAR NE WI. WILL
CARRY SLGT CHC OR CHC POPS OVER MOST OF THE CWA THIS AFTERNOON
AND EVENING...WITH THE HIGHEST POPS OVER CENTRAL AND FAR NE WI.
DRY CONDITIONS ARE EXPECTED OVERNIGHT...WITH PATCHY FOG EXPECTED
TO REDEVELOP. USED A BLEND OF THE TOP-PERFORMING GUIDANCE SETS
(WHICH HAVE BEEN TOUGH TO BEAT LATELY) FOR TEMPERATURES TODAY AND
TONIGHT. THEY SUPPORT HIGHS IN THE MIDDLE 70S TO LOWER 80S...
EXCEPT UPPER 60S AND LOWER 70S LAKESIDE...WITH LOWS IN THE MIDDLE
40S TO LOWER 50S NORTH...TO 55 TO 60 SOUTH.

ON FRIDAY...MOISTURE AND INSTABILITY IS EXPECTED TO INCREASE A
BIT DURING THE DAY. MODIFIED FCST SOUNDINGS SUPPORT CAPE OF
1500-2000 J/KG...WITH LI`S OF -5 TO -7. AN UPPER LEVEL TROF
WILL MOVE INTO THE REGION LATE IN THE DAY...AND SHOULD HELP
TRIGGER TSTM DEVELOPMENT. ALTHOUGH DEEP LAYER SHEAR IS FAIRLY
WEAK (10-20 KTS)...THE DEGREE OF INSTABILITY AND FAVORABLE WET
BULB ZERO HGTS AROUND 10K FT SUPPORT A THREAT OF ISOLD SVR TSTMS
WITH LARGE HAIL AND DAMAGING WINDS. HIGH TEMPERATURES SHOULD BE
QUITE SIMILAR TO TODAY...GENERALLY IN THE UPPER 70S AND LOWER
80S.

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 343 AM CDT THU JUL 31 2014

MEDIUM RANGE MODELS SHOW THAT SOME DEAMPLIFICATION WILL OCCUR TO THE
RIDGE TROUGH PATTERN ACROSS NORTH AMERICA BY EARLY THIS WEEKEND.
WILL STILL HAVE TO DEAL WITH FLATTENED TROUGHING OVER THE GREAT
LAKES...HOWEVER...THAT WILL PROVIDE PERIODIC PRECIP CHANCES.  THE
ECMWF AND GFS REMAIN IN GOOD AGREEMENT SO WILL CONTINUE TO BLEND
THESE MODELS.

FRIDAY NIGHT THROUGH SATURDAY NIGHT...THE DEEP UPPER TROUGH WILL
BEGIN TO LIFT TO THE NORTHEAST FRIDAY NIGHT...BUT WILL CONTINUE TO
PROVIDE SCT SHOWERS AND ISOLATED TSTORMS INTO THE EVENING BEFORE
DIMINISHING OVERNIGHT.  THEN AS THE TROUGH EXITS...WEAK SHORTWAVE
RIDGING BUILDS ACROSS THE REGION ON SATURDAY.  THE PREVIOUS SHIFT
FAVORED A DRY FORECAST...AND CANNOT ARGUE WITH THIS REASONING THOUGH
THE ECMWF CONTINUES TO SPIT OUT LIGHT QPF OVER NORTHEAST WISCONSIN.
THINK THIS IS OVERDONE THOUGH.  THEN A SHORTWAVE WILL MOVE INTO
ONTARIO AND DRAG A WEAK FRONT INTO NORTHWEST WISCONSIN LATE SATURDAY
NIGHT.  WILL INCREASE SKY COVER LATE BUT KEEP THE AREA DRY.

REST OF THE FORECAST...THE SHORTWAVE WILL PUSH THE FRONT ACROSS THE
REGION ON SUNDAY WHICH WILL GIVE THE REGION THE NEXT SIGNIFICANT
CHANCE OF SHOWERS AND THUNDERSTORMS.  THEN THE MODELS SHOW THE FRONT
STALLING ACROSS CENTRAL WISCONSIN SUNDAY NIGHT INTO TUESDAY...THOUGH
ITS NOT EXACTLY CLEAR WHERE THE FRONT ENDS UP BY TUESDAY.  SEEMS
THAT SUNDAY NIGHT AND MONDAY OFFER BETTER CHANCES OF PRECIP RATHER
THAN TUESDAY.  THEN ANOTHER SHORTWAVE ARRIVES BY THE MIDDLE OF NEXT
WEEK.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1040 PM CDT WED JUL 30 2014

SHOWERS WILL BE EXITING FOX VALLEY...LINGERING A BIT LONGER OVER
CENTRAL WHERE AIR MASS REMAINS UNSTABLE. LIGHT WINDS...DECREASING
CLOUDS...AND AVAILABLE MOISTURE FROM EVENING RAINS TO ALLOW AREAS
OF FOG TO DEVELOP ONCE AGAIN WITH VISIBILITY SIMILAR TO LOWER THAN
LAST NIGHT. LESS SHOWER ACTIVITY EXPECTED ON THU...THUS HAVE
STAYED DRY AT ALL TAF SITES.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
DENSE FOG ADVISORY UNTIL 8 AM CDT THIS MORNING FOR WIZ005-010-
018.
&&

$$

SHORT TERM.....KIECKBUSCH
LONG TERM......MPC
AVIATION.......TE






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