Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 261638
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1138 AM CDT FRI JUN 26 2015

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 247 AM CDT FRI JUN 26 2015

RAIN SHOWERS FROM YESTERDAY...COMBINED WITH LIGHT WINDS AND MOSTLY
CLEAR SKIES...HAS LED TO FOG ACROSS PORTIONS OF THE CWA EARLY THIS
MORNING. AT THIS TIME THE AREAS THAT HAVE BEEN MOST AFFECTED HAVE
BEEN NORTH CENTRAL WISCONSIN...WHERE VISIBILITIES HAVE FLIRTED
WITH THE 1 SM MARK. AT THIS TIME IT DOES NOT APPEAR THAT THIS WILL
BE A LONG LIVED WIDESPREAD DENSE FOG EVENT AS VISIBILITIES HAVE
BOUNCED AROUND QUITE A BIT EARLY THIS MORNING. THEREFORE WILL
HANDLE THE FOG WITH SPS STATEMENTS UNLESS IT BECOMES MUCH WORSE AS
THE NIGHT TIME HOURS ARE CURRENTLY THE SHORTEST THEY CAN BE DURING
THE YEAR.

INSTABILITY SHOWERS AND THUNDERSTORMS ARE AGAIN EXPECTED TODAY AS
A 500HPA TROUGH AND MID LEVEL SHORTWAVE TRACK THROUGH THE WESTERN
GREAT LAKES. MUCAPE VALUES DURING THE AFTERNOON HOURS SOAR TO
AROUND 500 J/KG...HOWEVER MODELS SHOW THE MAIN SHORTWAVE ENERGY
TRACKING TO OUR SOUTH THEREFORE WILL KEEP POP VALUES IN THE
SLIGHT CHANCE CATEGORY. DESPITE ABUNDANT SUNSHINE TODAY...COOL
NORTHEASTERLY FLOW WILL LIMIT HIGH TEMPERATURES TO THE MIDDLE 70S
ACROSS MUCH OF THE REGION...WITH HIGHS AROUND 70 NEAR THE
LAKESHORE.

SOME SHOWERS AND THUNDERSTORMS ARE POSSIBLE DURING THE EVENING
HOURS...HOWEVER ANY LINGERING CONVECTION IS EXPECTED TO END
QUICKLY THE THE LOSS OF DAYTIME HEATING GIVEN THE DIURNAL NATURE
OF THIS ACTIVITY. A SURFACE RIDGE IS EXPECTED TO PROVIDE DRY
CONDITIONS THE REST OF THE OVERNIGHT HOURS AND INTO SATURDAY.

MOSTLY CLEAR SKIES TONIGHT WILL MEAN OVERNIGHT LOWS WILL BE
SIMILAR TO THIS MORNING...WITH AFTERNOON HIGHS ON SATURDAY
EXPECTED TO BE A DEGREE OR TWO HIGHER THAN TODAY AS MODEST WARM
AIR ADVECTION BEGINS FROM THE WEST AHEAD OF AN APPROACHING LOW
PRESSURE SYSTEM.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 247 AM CDT FRI JUN 26 2015

HIGHLY AMPLIFIED FLOW CONSISTING OF A WRN CONUS UPR RDG AND ERN
CONUS UPR TROF TO PERSIST INTO EARLY NEXT WEEK BEFORE THE RDG
RETROGRADES INTO THE ERN PACIFIC AND WEAKENS A LITTLE TOWARD MID-
WEEK. THE GREAT LAKES REGION WL REMAIN UNDER THE INFLUENCE OF THE
UPR TROF WITH A NW FLOW BRINGING A PARADE OF SHORTWAVES THRU WI.
THIS SCENARIO WL PROVIDE FOR NEAR NORMAL TEMPS...BUT AN UNSETTLED
PATTERN WITH SEVERAL OPPORTUNITIES FOR PCPN. TRYING TO TIME THESE
PCPN EVENTS REMAINS THE BIGGEST FCST HURDLE.

THE NEXT SYSTEM TO AFFECT NE WI...IN THE FORM OF A SFC LOW...
CDFNT...MID-LEVEL SHORTWAVE TROF AND SEVERAL EMBEDDED
SHORTWAVES...IS FCST TO DROP SE INTO THE UPR MS VALLEY SAT NGT.
EXPECT TO SEE CLOUDS BEGIN TO OVERSPREAD NE WI AFTER MIDNGT...
HOWEVER THE BULK OF ANY PCPN WL REMAIN TO OUR WEST. MIN TEMPS TO
RANGE FROM THE LWR TO MID 50S NORTH/LAKESIDE...MID TO UPR 50S
SOUTH.

THIS SYSTEM WL CONT TO MOVE SE AND IMPACT THE WRN GREAT LAKES/
MIDWEST ON SUNDAY WITH A GOOD CHC OF SHWRS/TSTMS AFFECTING NE WI.
THE HIGHEST POPS REMAIN OVER CNTRL WI (LIKELY) CLOSER TO THE
STRONGER INSTABILITY...SFC LOW AND CDFNT. CAPES APPROACH 1500 J/KG
OVER CNTRL WI WITH LI`S AS LOW AS -4. WL HAVE TO WATCH THE STORMS
AS SOME MAY BECOME STRONG WITH SMALL HAIL POSSIBLE. FARTHER TO THE
EAST...THERE CONTS TO BE SOME MODEL DISAGREEMENT ON HOW FAR EAST
THE PCPN WL GET DURING THE AFTERNOON. PREVIOUS SHIFT PROVIDED A
GRADUAL TREND DOWN IN THE POPS TOWARD THE LAKESHORE AND THIS
CERTAINLY LOOKS PLAUSIBLE. MAX TEMPS TO RANGE FROM THE LWR 70S
N-CNTRL WI...TO THE UPR 70S OVER E-CNTRL WI.

PCPN CHCS WOULD CARRY OVER THRU MOST OF SUNDAY NGT AS THE SYSTEM
TRACKS TOWARD SRN SECTIONS OF THE GREAT LAKES. THE EVENUAL LOSS OF
DAYTIME HEATING WL LIMIT INSTABILITY TO A DEGREE...THUS POPS ONLY
IN THE CHC CATEGORY THRU THE NGT. MOSTLY CLOUDY SKIES WL HELP TO
HOLD TEMPS UP A BIT WITH READINGS GENERALLY IN THE MID TO UPR 50S.
NE WI TO RESIDE ON THE CYCLONIC SIDE OF THE SLOWLY DEPARTING
SYSTEM ON MON AND WHEN COMBINED WITH DAYTIME HEATING AND
ADDITIONAL SHORTWAVE ENERGY DROPPING SE THRU WI...EXPECT TO SEE
ANOTHER ROUND OF SCATTERED SHWRS/TSTMS DOT THE LANDSCAPE. WHILE
THE RISK OF SEVERE STORMS APPEARS TO BE MINIMAL AT THIS POINT ON
MON...DEW POINTS AROUND 60 DEGS COULD BRING A QUICK BURST OF HEAVY
RAIN. MAX TEMPS BEGINNING TO SOUTH LIKE A BROKEN RECORD WITH LWR
70S NORTH/LAKESIDE...MID TO UPR 70S SOUTH.

MUCH OF THIS PCPN WL DISSIPATE MON EVENING UPON SUNSET AS THE
ATMOSPHERE ATTEMPTS TO STABILIZE. BY TUE...THE WRN UPR RDG TO HAVE
WEAKENED A BIT AND BEGUN TO SHIFT TO THE WEST. UNFORTUNATELY...NE
WI TO REMAIN LOCKED IN A NW FLOW ALOFT WHICH WL CONT TO TRANSPORT
SHORTWAVE ENERGY THRU THE REGION. ANTICIPATE AT LEAST A CHC FOR
SHWRS/TSTMS TO POP UP ONCE AGAIN WITH MAX TEMPS HOLDING IN THE LWR
70S NORTH/NEAR LAKE MI AND MID TO UPR 70S SOUTH.

MAIN FOCUS HEADED TOWARD THE MIDDLE OF NEXT WEEK TO BE THE
HANDLING OF THE NEXT SUBSTANTIAL SYSTEM MOVING SE FROM THE NRN
PLAINS THRU THE MIDWEST. THE EXACT TRACK OF THIS SYSTEM WL BE
CRITICAL AS SOME OF THE MODELS KEEP THE SYSTEM FAR ENUF TO OUR
WEST SUCH THAT NE WI REMAINS COMPLETELY DRY FOR BOTH WED AND THU.
CONVERSELY...OTHER MODELS SEND THIS SYSTEM FARTHER EAST...THUS
BRINGING SHWRS/TSTMS TO NE WI WED/WED NGT. HAVE FOLLOWED THE
CONSENSUS SOLUTION FOR NOW DUE TO ALL THE UNCERTAINTY INVOLVED
WHICH ESSENTIALLY KEEPS SMALL POPS IN THE FCST FOR BOTH DAYS.
TEMPS TO REMAIN AT OR SLIGHTLY BELOW NORMAL WED AND THU.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1108 AM CDT FRI JUN 26 2015

SCT VFR CLOUD COVER IS EXPECTED THIS AFTERNOON. THERE IS A SMALL CHANCE
FOR SHOWERS AND THUNDERSTORMS LATE THIS AFTERNOON AND INTO THE
EARLY EVENING...WITH ISOLATED COVERAGE AT BEST. CLEAR SKIES AND
LIGHT WINDS COULD LEAD TO FOG ONCE AGAIN TONIGHT...WITH THE BEST
CHANCE AT RHI. LIFR VSBY DEVELOPED IN RHI LAST NIGHT AND GIVEN NOT
MUCH WILL CHANGE IN THE OVERALL WEATHER PATTERN...REPEATED LAST
NIGHTS CONDITIONS IN TONIGHT TAFS...WHICH WOULD INCLUDE THE LIFR
FOG AT RHI. CENTRAL AND EASTERN WISCONSIN TAF SITES ARE LESS
LIKELY TO SEE FOG...WITH ONLY A BRIEF TIME PERIOD WHERE MTW MAY
SEE MVFR VSBYS EARLY SATURDAY MORNING. ONCE ANY FOG LIFTS SATURDAYMORNING...VFR
CONDITIONS WILL RETURN TO NE WISCONSIN.

&&

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

$$

SHORT TERM.....KURIMSKI
LONG TERM......KALLAS
AVIATION.......ALLEN


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