Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 031750
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1250 PM CDT FRI JUL 3 2015

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SYNOPSIS...
ISSUED AT 317 AM CDT FRI JUL 3 2015

SEASONABLY WARM TEMPERATURES FOR THE INDEPENDENCE DAY
WEEKEND. SOME ISOLATED OR SCATTERED THUNDERSTORMS ARE POSSIBLE
AT TIMES...BUT THE BULK OF THE HOLIDAY WEEKEND WILL BE RAIN FREE.

THE CURRENT WNWLY UPR FLOW REGIME WL COME TO AN END AS THE UPR
RIDGE OVER WRN NOAM CONTS SHIFTG WWD INTO THE GULF OF ALASKA.
THAT WL RESULT IN CONSOLIDATION OF DOWNSTREAM SHRTWV ENERGY INTO A
LARGE SCALE UPR TROF OVER CENTRAL CANADA...SOUTH OF WHICH A WLY
UPR FLOW WL DEVELOP ACRS THE NORTH-CENTRAL CONUS. THE MAIN
WESTERLIES WL GRADUALLY REFORM S OF THE GULF OF AK RIDGE DURING
THE LATTER PART OF THE PERIOD. AS THAT HAPPENS...AN UPR TROF WL
DEVELOP NR THE WEST...WITH CONTD GENERALLY WESTERLY FLOW
DOWNSTREAM OVER THE NRN CONUS.

TEMPERATURES WILL EDGE UPWARD THE NEXT COUPLE DAYS...TO SEVERAL
DEGREES ABOVE NORMAL BY SUNDAY...DROP BACK TO BELOW NORMAL FOR A
COUPLE DAYS DURING THE MIDDLE OF NEXT WEEK...THEN WARM AGAIN LATE
IN THE WEEK. ALTHOUGH SOME PRECIPITATION IS POSSIBLE DURING THE
WEEKEND...THE MAIN RAIN MAKER WILL BE THE COLD FRONT CROSSING THE
AREA EARLY NEXT WEEK. THAT IS STARTING TO LOOK LIKE A GOOD
PRECIPITATION PRODUCER...SO PCPN AMNTS FOR THE PERIOD WL PROBABLY
END UP AOA NORMAL.
&&

.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 317 AM CDT FRI JUL 3 2015

PREV FCST SEEMED TO BE RIGHT ON TRACK. FEW CHGS WERE
NECESSARY...EVEN TO MOST DETAILS.

WK BOUNDARY WL SAG SWD INTO NRN WI BY EARLY EVENING. MEANWHILE
ALOFT...TAIL OF SHRTWV TRACKING ACRS ONTARIO WL BRUSH ACRS
NRN/NERN WI. THE BEST UPR SUPPORT WL ARRIVE BEFORE THE SFC
BOUNDARY...AND BE PULLING OFF TO THE NE AS THE BOUNDARY ARRIVES.
THIS SCENARIO SUGGESTS PCPN COVERAGE WL PROBABLY REMAIN SCT..SO
STUCK WITH CHC POPS. BULK SHEAR PROGGED TO BE ARND 20-25 KTS...
AND MID-LVL LAPSE RATES ONLY ARND 5 K/KM. GIVEN THE LIMITED
INSTABILITY AND SHEAR...SVR WX SEEMS UNLIKELY.

BOUNDARY SLOWLY SAGGING SWD THROUGH THE AREA OVERNIGHT LOOKS LIKE
ONE OF THOSE SITNS WHERE CONVECTION WANES DURING THE MID-LATE
EVENING...BUT TAKES ALONG TIME TO GO AWAY COMPLETELY. CARRIED SLGT
CHC POPS PAST MIDNIGHT.

THERE IS SOME DISAGREEMENT BETWEEN THE MODELS ON WHERE BOUNDARY
WL BE LOCATED SATURDAY. THOUGH NOT STG...UPR FLOW DOES TURN NW FOR
A WHILE. IT SEEMS MOST LIKELY THE FRONT WL EITHER BE ACRS THE SW
PART OF THE FCST AREA...OR IN SRN/WRN WI. AS SUCH...BEST CHC FOR
ANY AFTERNOON REDEVELOPMENT WL BE OVER THE SRN/SWRN PART OF THE
AREA. SOMEWHAT DRIER AIR MAY BE ABLE TO WORK INTO THE N/NE BY
AFTN...AND SHOULD KEEP THOSE AREAS RAIN-FREE.

TEMP FCST FOR MOST AREAS BASED ON A BLEND OF THE TOP PERFORMING
GUIDANCE PRODUCTS...AND SIMILAR TO PREV FCST. BUT AS
USUAL...ADJUSTMENTS WERE NEEDED NEAR THE LAKE AND BAY.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 317 AM CDT FRI JUL 3 2015

THE LATEST MEDIUM RANGE GUIDANCE IS IN DECENT AGREEMENT WITH A
STRONG FRONT MOVING THROUGH THE REGION EARLY NEXT WEEK.  THE GFS
REMAINS SLIGHTLY FASTER THAN THE ECMWF AND GEM...WHILE MOST
OPERATIONAL MODEL RUNS ARE FASTER THAN THE GFS ENSEMBLE MEAN.
THOUGH TIMING MIGHT STILL SHIFT SUBTLY...BELIEVE A GFS/ECMWF BLEND
IS THE WAY TO GO.  THEREAFTER...FLATTENED TROUGHING WILL EXIST OVER
THE NORTHERN CONUS BUT THERE ARE SOME INDICATIONS THAT A DISTURBANCE
WILL BE APPROACHING THE REGION BY NEXT THU OR FRI.  THE GFS IS MORE
CLOSELY ALIGNED WITH THE ENSEMBLE MEANS FOR LATER PERIODS.

SATURDAY NIGHT THROUGH SUNDAY NIGHT...THE STALLED FRONT ON SATURDAY
WILL RETURN NORTHWARD ON SATURDAY NIGHT...BUT LOSE DEFINITION IN THE
PROCESS.  AS A RESULT...WILL STICK WITH A DRY FORECAST AND SHOW
CLEARING SKIES.  SUNDAY LOOKS QUIET AND WARM WITH A LIGHT SOUTHERLY
BREEZE.  TEMPERATURES CONTINUE TO BECOME WARMER IN THE
GUIDANCE...AND NOW SUGGEST MID 80S FOR HIGHS.  WILL RAISE TEMPS A
DEGREE OR TWO.  CLOUDS WILL BE ON THE INCREASE ON SUNDAY NIGHT WHEN
THE STRONG FRONT MOVES INTO THE NORTHERN MISSISSIPPI VALLEY.  A
CHANCE OF PRECIP WILL ARRIVE OVER N-C WI LATE.  LOWS IN THE MID 60S.

REST OF THE FORECAST...THE FRONT WILL MOVE INTO CENTRAL WI DURING
THE MORNING...AND EASTERN WI DURING THE AFTERNOON.  THOUGH THERE
WILL BE PLENTY OF QG AND FGEN FORCING...ML CAPES PROJECTED BY THE
GFS OVER THE FOX VALLEY ONLY YIELDS ABOUT 500 J/KG.  0-6KM BULK
SHEAR DOES INCREASE RIGHT ALONG THE FRONT TO ABOUT 30 KTS AND PWATS
WILL BE APPROACHING 2.0 INCHES. SO APPEARS TO BE LOW RISK OF SEVERE
WEATHER AT THIS TIME...MAINLY ACROSS EASTERN WI WHERE THERE IS
POTENTIAL FOR GREATER SURFACE HEATING.  HEAVY RAINFALL MAY BE A
GREATER THREAT THAN SEVERE WEATHER GIVEN THE FORCING AND MOISTURE
AVAILABILITY.  THE FRONT WILL EXIT EASTERN WISCONSIN MONDAY
EVENING...AND HIGH PRESSURE WILL BUILD INTO THE REGION FOR THE REST
OF THE NIGHT AND INTO TUESDAY.  THE HIGH WILL BRING IN COOLER AND
DRIER CONDITIONS.  THE NEXT CHANCE OF RAIN THEN LOOKS TO OCCUR NEXT
THU OR FRI.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1249 PM CDT FRI JUL 3 2015

CDFNT OVER NRN SECTIONS OF THE GREAT LAKES THIS AFTERNOON IS FCST
TO SAG SOUTH AND REACH CNTRL SECTIONS OF MN AND WI TNGT BEFORE
PULLING UP STATIONARY. INCREASED INSTABILITY AHEAD OF THE FNT IS
FCST TO ALLOW ISOLATED/SCATTERED SHWR/TSTM ACTIVITY TO DEVELOP
OVER NRN WI LATER THIS AFTERNOON AND MOVE SE INTO CNTRL SECTIONS
OF WI THIS EVENING BEFORE DISSIPATING AS WE LOSE DAYTIME HEATING.
VFR CONDITIONS SHOULD DOMINATE...HOWEVER MVFR CIGS/VSBYS ARE
POSSIBLE UNDER ANY TSTM ACTIVITY. IN ADDITION...SOME PATCHY FOG IS
POSSIBLE LATE TNGT AS LOW-LEVEL MOISTURE CONTS TO INCREASE. THE
STALLED FNT IS FCST TO SLOWLY LIFT NORTH BY SAT AFTERNOON AND MAY
BE THE FOCUS FOR ADDITIONAL CHC OF SHWRS AND TSTMS. FINALLY...VSBL
SATL IMAGERY CONTS TO SHOW SMOKE FROM CANADIAN WILDFIRES DRIFTING
SEWD OVER THE NRN TIER OF STATES. HAVE NOT REDUCED VSBYS DUE TO
THIS SMOKE JUST YET IN THE TAFS...HOWEVER THIS WL NEED TO BE
MONITORED FOR POSSIBLE INCLUSION IN LATER FCSTS.
&&

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

$$

SYNOPSIS.......SKOWRONSKI
SHORT TERM.....SKOWRONSKI
LONG TERM......MPC
AVIATION.......AK


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