Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 051729
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1229 PM CDT SUN JUL 5 2015

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SYNOPSIS...
ISSUED AT 312 AM CDT SUN JUL 5 2015

WARM TODAY...A ROUND OF SHOWERS AND THUNDERSTORMS MONDAY AND
MONDAY EVENING...THEN MUCH COOLER BY MID-WEEK.

A FAIRLY STG UPR TROF WL CONSOLIDATE OVER CENTRAL CANADA THE NEXT
COUPLE DAYS...THE SRN EXTENT OF WHICH WL INITIALLY EXTEND INTO
THE NRN PLAINS. THAT WL RESULT IN A SEASONABLY STG BAND OF
WESTERLIES ACRS SRN CANADA AND THE NRN CONUS. THEN AS THE
AMPLITUDE OF THE FLOW ACRS CANADA WANES DURING THE REST OF THE
PERIOD...A SEPARATE SRN BRANCH OF THE FLOW WL GRADUALLY EVOLVE FM
THE DESERT SW TO NEW ENGLAND.

TEMPERATURES WL START OF ABOVE NORMAL...COOL TO BELOW NORMAL FOR
THE MIDDLE OF THE WORK WEEK...THEN WARM AGAIN LATE IN THE WEEK.
WITH ONE SYSTEM /MON-MON NGT/ THAT LOOKS LIKE A PRETTY GOOD PRECIP
PRODUCER...AND THE POTENTIAL FOR MORE PCPN EVENTS LATE IN THE
PERIOD WITH THE EVOLVING SRN STREAM...AMNTS SEEM LIKELY TO END UP
AOA NORMAL FOR THE PERIOD.
&&

.SHORT TERM...TODAY...TONIGHT...AND MONDAY
ISSUED AT 312 AM CDT SUN JUL 5 2015

QUIET TODAY AND TNGT. PCPN ACRS NRN MN SEEMS TO HAVE GOTTEN E OF
WHERE THE MODELS WERE FCSTG IT...BUT IT LOOKS TO BE WEAKENING NOW.
WILL KEEP WATCHING IT...BUT GIVEN THE STABLE AIR MASS ACRS THE
AREA IT SEEMS LIKELY IT WL DISSIPATE TO OUR W THIS MORNING.

OTHERWISE...MAIN SHORT-TERM FCST ISSUE IS PCPN WITH THE COLD FRONT
EXPECTED TO CROSS THE RGN MON/MON NGT. STILL SOME DIFFERENCES
AMONG THE MODELS ON THE TIMING OF FROPA. THE NAM WAS THE
FASTEST...WITH THE ECMWF THE SLOWEST. TRENDED THE FCST TOWARD THE
SLOWER EURO...ESPECIALLY SINCE IT NOW SEEMS LIKELY TAIL OF SHRTWV
WRAPPING INTO DEVELOPING CANADIAN UPR TROF WL INDUCE A WAVE ON THE
FRONT. THE SLOWER MVMT OF THE FRONT WL ALLOW THE ERN 1/2 OF THE
FCST AREA MORE OF A CHANCE TO WARM UP...SO BASED MAX TEMPS
PRIMARILY ON BLEND OF EURO AND SREF-BASED PRODUCTS.

SPC INDICATING A MARGINAL RISK OF SVR ACRS THE AREA IN THE DAY 2
CONVECTIVE OUTLOOK...BASICALLY MAINTAINING THE FCST FM THE OLD DAY
3 OUTLOOK. THE BEST SHEAR WL LAG THE FRONT. BUT THE SLOWER ARRIVAL
OF THE FRONT WOULD SUGGEST THE E MAY BE ABLE TO DESTABILIZE BEFORE
CONVECTION FM THE W ARRIVES...PROVIDED MID-HIGH CLDS FM CONVECTION
TO THE W DON/T TOTALLY OVERSPREAD THE AREA BEFORE DAYBREAK. WL
CONT TO MENTION THE LIKELIHOOD OF HVY RAIN AND SOME POTENTIAL FOR
SVR WX IN THE HWO.

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
ISSUED AT 312 AM CDT SUN JUL 5 2015

THE LATEST ENSEMBLE GUIDANCE SUPPORTS A BLEND OF THE ECMWF AND SREF
FOR THE FRONTAL PASSAGE ON MONDAY NIGHT.  THEREAFTER...THE ECMWF
ENSEMBLE MEAN SHOWS A WEAKNESS IN THE 500MB HEIGHT PATTERN NEXT
WEEKEND VERSUS BUILDING HEIGHTS DEPICTED IN THE GFS ENSEMBLE MEAN.
THE OPERATIONAL MODELS SUPPORT THE ECMWF ENSEMBLE MEAN WHICH IS
CLOSER TO THE OPERATIONAL GFS. SO WILL USE THESE MODELS FOR LATER
PERIODS.

MONDAY NIGHT THROUGH TUESDAY NIGHT...LOW PRESSURE WILL BE MOVING NE
OVER LAKE SUPERIOR IN THE EVENING...WHILE IT PUSHES A STRONG FRONT
FROM CENTRAL WI TO NORTHERN LAKE MICHIGAN.  AHEAD OF THE FRONT...ML
CAPES RANGING FROM ABOUT 500 J/KG OVER FAR NE WI TO AROUND 1000 J/KG
OVER EAST-CENTRAL WI...AND 0-6KM BULK SHEAR AROUND 25-30 KTS WILL
SUPPORT A LOW CHANCE OF SEVERE STORMS CONTINUING INTO THE EVENING
OVER EASTERN WI.  DAMAGING WINDS AND LARGE HAIL WILL CONTINUE TO BE
THE MAIN THREATS. PWATS WILL BE APPROACHING 2.0 INCHES WHICH MAKES
LOCALLY HEAVY RAINFALL PERHAPS EVEN A BIGGER THREAT.  PRECIP WILL
EXIT ACROSS FAR EASTERN WI SHORTLY AFTER MIDNIGHT AND NORTHWEST
WINDS WILL ADVECT COOLER AND DRIER AIR INTO THE REGION.  THEN HIGH
PRESSURE MOVES ACROSS THE REGION TUESDAY AND TUESDAY NIGHT WHICH
LOOK MOSTLY CLEAR AND QUIET.

REST OF THE FORECAST...HIGH PRESSURE WILL HANG AROUND FOR WEDNESDAY
TO CONTINUE THE QUIET CONDITIONS.  GUIDANCE HAS BEEN WAFFLING AROUND
A LITTLE ABOUT MOVING WEAK SHORTWAVE ENERGY OVERHEAD FOR THURSDAY.
THE EXTENDED INITIALIZATION INCLUDED A SLIGHT CHANCE OF PRECIP SO
WILL LEAVE IN THE FORECAST.  THOUGH ITS ONE OF THOSE SCENARIOS WHERE
IF THE INITIALIZATION WAS DRY...WOULD HAVE LEFT THE FORECAST AS DRY.
BETTER CHANCES OF PRECIP LOOK TO OCCUR NEXT SAT INTO SUNDAY WHEN
SUBTROPICAL RIDGING TRIES TO BUILD INTO THE WESTERN GREAT LAKES.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1228 PM CDT SUN JUL 5 2015

MAINLY VFR CONDITIONS EXPECTED THIS AFTERNOON INTO THE EVENING
WITH CU FIELD TO BE IN THE 4K-5K FT RANGE. THESE CLOUDS TO
DISSIPATE THIS EVENING BEFORE PATCHY FOG DEVELOPS ONCE AGAIN LATER
TNGT. VSBYS COULD DROP INTO THE MVFR RANGE...BUT NOT ANY LOWER AS
AN INCREASING S-SW WIND DEVELOPS. HAVE INCLUDED LLWS FOR THE
OVRNGT HOURS IN ALL TAF SITES. CONDITIONS ARE FCST TO GRADUALLY
DETERIORATE FROM WEST TO EAST ON MON AS A CDFNT PUSHES INTO WI.
PRE-FRONTAL SHWRS/FEW STORMS MAY REACH CNTRL WI TAF SITES MID-LATE
MORNING...HOWEVER MAIN ACTION TO PRIMARILY BE IN THE AFTERNOON
ONCE THE CDFNT ARRIVES. POTENTIAL FOR HEAVY RAIN COULD LIMIT VSBYS
TO IFR CONDITIONS UNDER ANY TSTMS.
&&

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

$$

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


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