Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 231716
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1216 PM CDT THU APR 23 2015

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SYNOPSIS...
ISSUED AT 353 AM CDT THU APR 23 2015

A FAIRLY DRY PATTERN WITH BELOW NORMAL TEMPERATURES THROUGH THE
WEEKEND...THEN WARMER NEXT WEEK.

UPPER PATTERN OVER NERN NOAM WL BECOME VERY BLOCKY AS POSITIVE
UPR HEIGHT ANOMALY CONSOLIDATES OVER THE CANADIAN ARCHIPELAGO THE
NEXT COUPLE DAYS...NORTH OF A DEEP NEGATIVE ANOMALY/UPR TROF
PRESENTLY LOCATED OVER ONTARIO/THE GREAT LAKES REGION. THE UPR
TROF WL BECOME ELONGATED ALONG AN EAST/WEST AXIS...WITH THE CORE OF
THE NEGATIVE ANOMALY SHIFTG TOWARD NEW ENGLAND. THE FCST AREA IS
STILL EXPECTED TO FEEL THE EFFECTS OF THE DEVELOPING NERN NOAM
BLOCK...THOUGH THE BLOCK IS EXPECTED TO BE LOCATED A LITTLE
FARTHER NE THAN FCST BY THE MODELS A FEW DAYS AGO. THAT WL AT
LEAST OPEN THE DOOR FOR SOME LGT PCPN WITH SYSTEMS HEADING IN FM
THE WEST...THOUGH THE BULK OF THE PCPN WITH THOSE SYSTEMS STILL
SEEMS LIKELY TO SHIFT ARND THE FCST AREA TO THE S.

THE PRESENCE OF THE UPR LOW TO OUR NE WL KEEP A COOL PATTERN IN
PLACE FOR MUCH OF THE FCST PERIOD. TEMPERATURES WL START OUT
SIGNIFICANTLY BELOW NORMAL...BUT THE COLDEST TEMPERATURES HAVE
ALREADY OCCURRED...WITH A SLOW MODERATION EXPECTED DURING THE
PERIOD. THE PROSPECTS FOR GETTING AT LEAST SOME LGT PCPN LOOK A
LITTLE BETTER THAN YDA...THOUGH PCPN AMNTS FOR THE NEXT 7 DAYS ARE
STILL LIKELY TO END UP BLO NORMAL.
&&

.SHORT TERM...TODAY...TONIGHT...AND FRIDAY
ISSUED AT 353 AM CDT THU APR 23 2015

CLOUD DECK EMBEDDED WITHIN COLD CYCLONIC NWLY FLOW WAS SHIFTG E
ACRS THE FCST AREA EARLY THIS MORNING. FCST SOUNDINGS SUGGEST SOME
ADDITIONAL CONVECTIVE CLOUDINESS WL FORM AFTER SUNRISE AS THE
GROUND STARTS TO HEAT UP...BUT CONTD DRYING AND WARMING ALOFT WL
LIKELY RESULT IN MOST OF THE CLDS DISSIPATING BY MID-LATE AFTN.
GENERATED SKYCON GRIDS WITH THIS TREND IN MIND...THOUGH SOME
ADJUSTMENT WL PROBABLY END UP BEING NECESSARY. LINGERING SNOW
FLURRIES IN N-C WI SHOULD END THIS MORNING. STAYED CLOSE TO BLEND
OF TOP PERFORMING GUIDANCE PRODUCTS FOR MAX TEMPS. MAXES SHOULD BE
7-10 F DEG WARMER THAN YDA DUE TO MODERATION OF THE AIR MASS AND
MORE SUN.

LOW-LEVEL RIDGE WL SHIFT ACRS THE RGN TNGT. SKIES ARE LIKELY TO BE
CLEAR...AT LEAST EARLY IN THE NGT. SOME CI AND MAYBE EVEN SOME
HIGH AC WL MV IN FM THE W LATER IN THE NGT. WENT WITH BLEND OF THE
COLDER GUIDANCE PRODUCTS. THIS RESULTED IN LOWERING MINS A LITTLE
FM PREV FCST...WHICH SEEMED REASONABLE GIVE THE FAVORABLE SET-UP
FOR TEMPS TO TUMBLE AT THE CLIMATOLOGICAL COOL SPOTS.

THE LATEST RUNS OF MOST OF THE MODELS WERE FASTER BRINGING PCPN
WITH APPROACHING SYSTEM INTO THE FCST AREA...WITH MANY NOW
GETTING PCPN INTO THE W DURING FRI AFTN. BUT THE 00Z ECMWF WAS
STILL DRY...AND THAT MAY NOT BE A BAD IDEA GIVEN THE DRY AIR MASS
THAT WL BE LINGERING IN THE WAKE OF THE DEPARTING LOW-LEVEL RIDGE.
INTRODUCED LOW POPS INTO THE FAR W DURING THE LATE AFTN...BUT
STUCK WITH DRY FCST FOR THE MAJORITY OF THE FCST AREA.

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 353 AM CDT THU APR 23 2015

A 500 MB LOW AND SURFACE LOW PRESSURE SYSTEM WILL BRING A CHANCE
FOR PRECIPITATION TO MAINLY WESTERN AND SOUTHERN WISCONSIN ON
FRIDAY NIGHT/EARLY SATURDAY AS THE SYSTEMS PASS SOUTH OF THE
STATE. THE 00Z ECMWF CONTINUED TO KEPT MOST...IF NOT ALL...OF ITS
QPF OUT OF THE AREA WHILE THE 00Z GFS/NAM/GEM-NH ALL SPREAD QPF
ACROSS MUCH OF THE FORECAST AREA. HAVE GONE CLOSER TO THE EC
SOLUTION BUT STILL HAVE SOME CHANCE POPS FOR A SMALL PART OF THE
AREA...WITH SLIGHT CHANCE POPS EXTENDING FARTHER NORTH AND EAST.

AN UPPER LEVEL RIDGE AND SURFACE HIGH PRESSURE SHOULD RESULT IN A
PERIOD OF DRY WEATHER THROUGH MONDAY NIGHT...AND DAYTIME
TEMPERATURES SHOULD AT LEAST GET WITHIN 5 DEGREES OF NORMAL
DURING THE FIRST HALF OF THE WEEK.

A SIGNIFICANT SHORT WAVE IS EXPECTED TO MOVE INTO THE REGION
TUESDAY INTO WEDNESDAY. MODELS SHOWED SOME TIMING DIFFERENCES BUT
APPEARED TO PRODUCE LITTLE OR NO QPF. CONSIDERING THE STRENGTH OF
THE SYSTEM AND THE POPS THAT WERE IN THE FORECAST FOR TUESDAY INTO
TUESDAY NIGHT FROM THE BLENDED SOLUTION...WAS NOT SURE THAT
REMOVING THE POPS WOULD BE A GOOD IDEA.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1215 PM CDT THU APR 23 2015

DRIER AIR ON NORTHWEST WINDS WILL POUR INTO THE AREA TODAY.
PATCHY MVFR CIGS EARLY TODAY CONTINUE TO DIMINISH AND MOVE TO THE
EAST WHILE VFR CONDITIONS BECOME WIDESPREAD. VFR CONDITIONS WILL
TONIGHT INTO FRIDAY...MID TO HIGH LEVEL CLOUDS WILL BE ON THE
INCREASE FROM THE WEST FRIDAY AFTERNOON.
&&

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

$$

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






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