Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 032218
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
518 PM CDT THU SEP 3 2015

UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE

.SYNOPSIS...
ISSUED AT 220 PM CDT THU SEP 3 2015

REMAINING HUMID AND TURNING VERY WARM AGAIN BY THE WEEKEND...THEN
COOLER AND DRIER NEXT WEEK.

THE LARGE SCALE PATTERN INVOF NOAM IS CURRENTLY DOMINATED BY A
TROF OVER ALBERTA...AND BROAD DOWNSTREAM RIDGING ACRS THE CENTRAL
AND ERN CONUS. AS THE WRN TROF SHARPENS/DEEPENS SWD DOWN THE WEST
COAST THE NEXT COUPLE DAYS...DOWNSTREAM RIDGE WL BUILD NEWD INTO
ONTARIO. THE PATTERN WL DEAMPLIFY AND BECOME PROGRESSIVE NEXT WEEK
AS THE ENERGY FM THE WRN TROF EJECTS/SHEARS ENEWD INTO THE
DOWNSTREAM RIDGE. THE END RESULT WILL LIKELY BE A TRANSITION BACK
TO A PATTERN WITH RIDGING NR THE COASTS AND A BROAD TROF OVER
CENTRAL NOAM BY THE END OF THE PERIOD.

THE UPR PATTERN WL KEEP HUMID AIR ACRS THE AREA THROUGH MOST OF
THE UPCOMING HOLIDAY WEEKEND. TEMPERATURES WILL RISE BACK TO VERY
WARM LEVELS BY THE WEEKEND...THEN TEMPERATURES AND HUMIDITIES WL
FALL BACK CLOSER TO SEASONAL NORMALS NEXT WEEK. DESPITE THE
ABUNDANT MOISTURE ACRS THE AREA...FORCING WL BE SUBTLE UNTIL LATE
IN THE HOLIDAY WEEKEND. PCPN AMNTS WL FOR THE MOST PART DEPEND ON
HOW MUCH RAIN OCCURS WITH THE FRONTAL SYSTEM CROSSING THE AREA
LATE SUN NGT/MONDAY.
&&

.SHORT TERM...TONIGHT AND FRIDAY
ISSUED AT 220 PM CDT THU SEP 3 2015

MAIN WEATHER FOCUS THROUGH FRIDAY WILL BE THE FOG POTENTIAL
TONIGHT...AND PRECIP CHANCES FRIDAY AFTERNOON. OVERALL
THOUGH...NO MAJOR IMPACTS EXPECTED TO THE CWA.

MESOANALYSIS THIS AFTERNOON SHOWED A WEAK FRONTAL BOUNDARY SLOWLY
SAGGING SOUTH TOWARDS SOUTHERN WISCONSIN. THIS FRONT IS OUTSIDE OF
OUR CWA...HOWEVER ITS EFFECTS CAN STILL BE FELT AS TEMPERATURES
AND DEWPOINTS ARE COOLER THAN THEY HAVE BEEN THE PAST FEW DAYS.
PERSISTENT CLOUD COVER UNDER A STRONG LOW LEVEL INVERSION HAS NOT
HELPED OUR TEMPERATURES EITHER...WITH ONLY NORTH CENTRAL WISCONSIN
SEEING PEAKS OF SUN BASED ON THE TREND ON THE VISIBLE SATELLITE
TODAY.

CLOUDS SHOULD GRADUALLY DISSIPATE FROM WEST TO EAST THIS EVENING
AND EARLY TONIGHT AS DRIER AIR AND STRONGER SUBSIDENCE PUSHES
INTO NORTHEAST WISCONSIN. A SHORTWAVE WILL BE STUCK JUST TO OUR
EAST...SO CLOUDS SHOULD LINGER THROUGH THE NIGHT OVER EASTERN
PORTIONS OF WISCONSIN...WITH PARTLY CLOUDY SKIES ELSEWHERE. WITH
BREAKS IN THE CLOUDS AND LIGHT WINDS...ANOTHER NIGHT OF FOG IS
ANTICIPATED. HESITATED TO PUT IN ANY WIDESPREAD DENSE FOG AS WE
DID NOT RECEIVE ANY PRECIP TODAY...BUT IN GENERALLY THE LOWEST
VISIBILITIES SHOULD BE OVER NORTH CENTRAL WISCONSIN WHERE CLOUDS
WILL CLEAR OUT THE MOST. DECREASED OVERNIGHT LOWS ACROSS THE AREA
TO REFLECT THE FACT THAT WE DID NOT WARM UP AS MUCH AS ANTICIPATED
THIS AFTERNOON. THIS MATCHED UP WELL WITH THE BEST PERFORMING
GUIDANCE TRENDS.

OTHER THAN OVER THE NEARSHORE WATERS...FOG SHOULD LIFT FRIDAY
MORNING. AFTER THAT...SKIES SHOULD GRADUALLY BECOME PARTLY CLOUDY
TO MOSTLY SUNNY BY EARLY AFTERNOON AS THE LOW LEVEL INVERSION
ERODES. THE UPPER LEVEL DISTURBANCE WILL CONTINUE TO SPIN
OVER LOWER MICHIGAN...SO EXPECT THE EAST TO SEE MORE CLOUDS THAN
SUN.

THE QUESTION THEN TURNS TO WHETHER OR NOT SHOWERS AND
THUNDERSTORMS WILL DEVELOP FRIDAY AFTERNOON. NONE OF THE HI- RES
MODELS HAD ANY PRECIP ON FRIDAY...AND THESE MODELS DID THE BEST
WITH HANDLING TODAYS LACK OF PRECIPITATION. HOWEVER...BOTH THE NAM
AND GFS SHOW A PIECE OF ENERGY AND MODERATE FORCING MOVING OVER
CENTRAL AND EAST CENTRAL WISCONSIN AFTER 18Z FRIDAY. GIVEN THE
AIRMASS IS SO MOIST...IT WONT TAKE A LOT TO SQUEEZE OUT SOME RAIN.
ADD IN SOME WEAK MID- LEVEL INSTABILITY AS SHOWN ON BUFKIT
SOUNDINGS...FELT IT WAS WORTH KEEPING POPS IN THE FCST FOR FRIDAY
AFTERNOON DESPITE A DRIER TREND ON SOME OF THE HI- RES MODELS.
OTHERWISE...ANOTHER WARM AND HUMID DAY IS EXPECTED...THOUGH TOOK
HIGH TEMPS ON FRIDAY DOWN A BIT PER GUIDANCE TRENDS.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY
ISSUED AT 220 PM CDT THU SEP 3 2015

FCST AREA WL REMAIN WITHIN UPR RIDGE POSN. BUT WITH WK UPPER
CIRCULATION/SHEAR AXIS HANGING BACK INTO THE FCST ARE FM THE
E...IT/S IMPOSSIBLE TO ABSOLUTELY RULE OUT PCPN DURING THE END OF
THE WORK WEEK AND FOR MUCH OF THE WEEKEND...AND ANY STORMS THAT
FORM COULD PRODUCE LOCALLY HEAVY RAIN. GIVEN THE UNCERTAINTY/
DIFFICULTY IN PINNING DOWN PCPN CHCS IN THIS PATTERN...TRIED TO
MAINTAIN SOME CONTINUITY WITH PREVIOUS FCST FRI NGT-SAT NGT. BY
SUN...BEST PCPN CHCS SHOULD GET FOCUSED BACK W NEAR THE ADVANCING
FRONT...THOUGH WHETHER OR NOT THAT PCPN MAKES IT FAR ENOUGH E TO
AFFECT THE FCST AREA IS ANOTHER QUESTION. FEELING IS THAT FRONT WL
PROBABLY SLOW AS IT ADVANCES TOWARD AMPLIFIED UPR RIDGE. PULLED
PCPN FM THE SE PART OF THE FCST AREA FOR NOW...AND WOULD NOT BE
SURPRISED IF WE EVENTUALLY NEED TO DELAY PCPN FURTHER.

FOG WL CONT TO BE AN ISSUE AT NGT...ESP FRI NGT WHEN WINDS WL BE
LIGHTER. STUCK CLOSE TO A BLEND OF THE TOP PERFORMING GUIDANCE
PRODUCTS FOR TEMPERATURES.

NO SIG CHANGES WERE NECESSARY TO EXTENDED FORECAST INITIALIZATION
GRIDS GENERATED FROM A BROAD-BASED BLEND OF GUIDANCE PRODUCTS.
&&

.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 518 PM CDT THU SEP 3 2015

SATELLITE TRENDS LATE THIS AFTERNOON CONTINUE TO SHOW A GRADUAL
EROSION OF THE MVFR CIGS EXTENDING OVER CENTRAL AND EAST CENTRAL
WISCONSIN. OBSERVATIONS ACROSS NORTHERN WISCONSIN INDICATE
MAINLY VFR CIGS. WHILE SOME IMPROVEMENT CAN BE EXPECTED THIS
EVENING...CLEARING SKIES AND LIGHT EAST WINDS WILL COMBINE WITH
THE SURFACE DEWPOINTS IN THE 60S TO PRODUCE ARES OF MVFR/IFR
CIGS/VSBYS OVERNIGHT. AS HAS BEEN THE CASE THE LAST FEW
MORNINGS...WILL TAKE MUCH OF THE MORNING IF NOT ALL TO IMPROVE
CONDITIONS TO VFR LEVELS.
&&

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

$$

SYNOPSIS.......SKOWRONSKI
SHORT TERM.....ALLEN
LONG TERM......SKOWRONSKI
AVIATION.......TDH



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