Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 221735
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1235 PM CDT WED APR 22 2015

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SYNOPSIS...
ISSUED AT 322 AM CDT WED APR 22 2015

MOSTLY CLOUDY AND CHILLY AGAIN TODAY WITH SOME LINGERING LIGHT
PRECIPITATION...ESPECIALLY NORTH. RELATIVELY TRANQUIL FOR THE
REST OF THE WEEK AND THE UPCOMING WEEKEND...BUT WITH CONTINUED
BELOW NORMAL TEMPERATURES.

HIGHLY AMPLIFIED LARGE SCALE PATTERN ACRS NOAM WILL EVOLVE INTO A
VERY BLOCKY CONFIGURATION AS POSITIVE UPR HEIGHT ANOMALY BUILDS
OVER THE CANADIAN ARCHIPELAGO...NORTH OF A DEEP NEGATIVE
ANOMALY/UPR TROF OVER ONTARIO/THE GREAT LAKES REGION. THE CORE OF
THE NEGATIVE ANOMALY WILL GRADUALLY SHIFT EAST WITH TIME...
ALLOWING UPR HEIGHTS ACRS THE FCST AREA TO REBOUND SOME FOR THE
WEEKEND AND EARLY NEXT WEEK.

THIS IS A CHILLY WEATHER PATTERN FOR THE FCST AREA...ESPECIALLY
DURING THE EARLY PART OF THE FCST PERIOD. TEMPERATURES TODAY WILL
RUN 15 TO 20 F DEG BELOW NORMAL. THAT WILL MODERATE TO A MORE
MODEST 5 F DEG BELOW NORMAL BY EARLY NEXT WEEK. ALTHOUGH SOME SCT
LGT PCPN IS POSSIBLE AT TIMES...SIG WX PRODUCING SYSTEMS ARE
LIKELY TO BE SHUNTED ARND THE RGN BY THE BLOCK. AS A RESULT...PCPN
AMNTS FOR THE NEXT 7 DAYS ARE LIKELY TO END UP MUCH BLO NORMAL.
&&

.SHORT TERM...TODAY...TONIGHT...AND THURSDAY
ISSUED AT 322 AM CDT WED APR 22 2015

COLD CYCLONIC UPR FLOW WL CONT ACRS THE AREA TODAY. UPR HEIGHTS
START TO REBOUND...THOUGH THE FCST AREA WL REMAIN ON THE CYCLONIC
SIDE OF THE JET. CONVECTIVE CLDS DUE TO DAYTIME HEATING SHOULD
FILL IN ANY HOLES IN THE LARGE CLD DECK ACRS THE RGN. EXPECT AN
UPTICK IN PCPN AGAIN TDA...THOUGH NOT NEARLY TO THE EXTENT WE SAW
YDA. EXCEPT FOR THE N WHERE LAKE-EFFECT SHSN WL CONTINUE...MOST OF
THE REST OF THE PCPN WL PROBABLY BEST BE DESCRIBED AS SPRINKLES/
FLURRIES...SO WENT THAT ROUTE WITH THE FCST.

CLDS WL DECREASE OVERNIGHT...THOUGH WITH THE FCST AREA STILL ON
THE CYCLONIC SIDE OF THE JET AND FLOW OFF LAKE SUPERIOR IT SEEMS
UNLIKELY WE WL TOTALLY CLEAR OUT. IT/S MORE LIKELY WE WL HAVE
PATCHES OF CLDS MOVG ACRS THE AREA. MIN TEMPS WL BE TRICKY DUE TO
LIGHTER WINDS AND THE POTENTIAL FOR AT LEAST PERIODS OF CLR SKIES.
STAYED CLOSE TO BLEND OF GUIDANCE FOR NOW.

SOME CONVECTIVE CLDS WL PROBABLY FORM AGAIN THU..ESP IN THE EAST.
BUT WITH JET AXIS FINALLY SHIFTG EWD DURING THE DAY...MOST OF THE
AREA SHOULD SEE PLENTY OF SUN BY MID-LATE AFTN. THOUGH THE AIR
MASS ACRS THE RGN WL STILL BE QUITE CHILLY...THE SUNSHINE SHOULD
HELP START THE TEMPERTURE REBOUND.

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
ISSUED AT 322 AM CDT WED APR 22 2015

A MID LEVEL CYCLONE OVER THE GREAT LAKES REGION WILL MOVE TO THE NEW
ENGLAND STATES BY THE START OF THE LONG TERM FORECAST. AT THE SAME
TIME...A RIDGE WILL APPROACH THE AREA FROM THE WEST. MODELS WERE
SHOWING DIFFERENCES IN STRENGTH AND TIMING OF SYSTEMS...STARTING
WITH THE ONE THAT WILL EITHER BRING PRECIPITATION INTO THE
FORECAST AREA OR KEEP IT JUST TO OUR SOUTH...DEPENDING ON THE
MODEL OF CHOICE. THE 00Z GFS WAS FARTHER NORTH WITH THE SYSTEM AND
HAD SOME QPF INTO CENTRAL WISCONSIN...WHILE THE 00Z ECMWF WAS A
LITTLE FARTHER TO THE SOUTH AND KEPT THE FORECAST AREA DRY. HAVE
OPTED TO GO WITH MAINLY SLIGHT CHANCES ON FRIDAY NIGHT...WHICH
LINES UP WELL WITH SURROUNDING FORECAST GRIDS. UPPER AND SURFACE
RIDGES SHOULD KEEP THE ENTIRE AREA DRY FOR SATURDAY THROUGH
SUNDAY. AFTER THAT...MAINLY SLIGHT CHANCE POPS SHOW UP FOR THE
REST OF THE FORECAST DUE TO BLENDING OF MODELS WITH TIMING
DIFFERENCES. A SLIGHT WARM UP CAN BE EXPECTED FOR EARLY NEXT WEEK
BUT TEMPERATURES WILL STILL BE SEVERAL DEGREES BELOW NORMAL
THROUGH TUESDAY.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1235 PM CDT WED APR 22 2015

PLENTY OF HI-END MVFR/LOW-END VFR CONDITIONS TO PREVAIL THIS
AFTERNOON INTO THE EVENING HOURS AS MOISTURE CONTS TO WRAP-AROUND
A LARGE...CLOSED AREA OF LOW PRES OVER E-CNTRL ONTARIO. MAINLY SCT
RAIN/SNOW SHWRS WL ALSO PERSIST INTO THE EVENING BEFORE
DIMINISHING WITH THE LOSS OF DAYTIME HEATING. EXCEPTION WOULD BE
THE RHI TAF SITE WHERE LAKE EFFECT SNOW SHWRS/FLURRIES/CLOUDS TO
PERSIST THRU MUCH OF TNGT WITH CIGS IN THE MVFR CATEGORY. A RDG OF
HI PRES IS PROGGED TO GRADUALLY PUSH INTO WI ON THU. FAIR WX CU IN
THE LOW-END VFR RANGE SHOULD DEVELOP IN THE MORNING...THEN TEND TO
DISSIPATE IN THE AFTERNOON AS THE RDG BUILDS EAST. ANTICIPATE
WIDESPREAD VFR CONDITIONS BY THU AFTERNOON.
&&

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

$$

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






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