Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 191800
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
100 PM CDT SAT APR 19 2014

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.UPDATE...
ISSUED AT 1025 AM CDT SAT APR 19 2014

15Z RADAR MOSAIC SHOWED THE LEADING EDGE OF THE RAIN WELL TO THE
WEST OF THE FORECAST AREA. 12Z GRB SOUNDING HAD QUITE A BIT OF DRY
AIR BELOW 700MB AND SURFACE DEW POINT DEPRESSIONS FROM 15Z
OBSERVATIONS WERE MOSTLY IN THE 10 TO 20F DEGREE RANGE. 11Z HRRR
COMPOSITE REFLECTIVITY DID NOT SHOW ECHOES ACROSS NORTH CENTRAL
WISCONSIN UNTIL AROUND 00Z. 12Z NAM WAS PRETTY DRY AS WELL...SO
HAVE PUSHED BACK THE ONSET OF THE RAIN TODAY...KEEPING AT LEAST
THE SOUTHEAST HALF OF THE FORECAST AREA DRY THROUGH 00Z. MAY NEED
TO PUSH THINGS BACK FOR THIS EVENING AS WELL...BUT WILL FURTHER
REVIEW THE LATEST GUIDANCE BEFORE MAKING ANY CHANGES TO THAT
PERIOD.
&&

.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 341 AM CDT SAT APR 19 2014

PCPN TRENDS AND TEMPERATURES WILL BE THE MAIN FCST CONCERNS.

MODELS HAVE SLOWED DOWN THE PROGRESSION OF THE PCPN ASSOCIATED
WITH A WEAK FRONTAL BOUNDARY TODAY AND TONIGHT. RAINFALL SHOULD BE
CONFINED TO OUR FAR NW COUNTIES TODAY...WHERE A 40-50 KT LLJ AND
SOME UPPER LEVEL DIVG WILL BE FOCUSED. THE PCPN WILL GRADUALLY
SHIFT SOUTHEAST TONIGHT...WITH THE HIGHEST POPS OVER FAR NE
WI...WHERE THE LLJ AND UPPER LEVEL DIVG WILL TAKE AIM. THE BEST
PCPN CHANCES WILL BE FOUND OVER C/EC WI ON SUNDAY...WITH RAINFALL
TAPERING OFF OVER OVER NORTHERN WI. HAVE OPTED TO LEAVE THUNDER
OUT OF THE FCST THROUGH THE PERIOD...AS INSTABILITY IS VERY
MARGINAL. HAVE ADDED SOME PATCHY FOG OVER NC/FAR NE WI LATE
TONIGHT INTO EARLY SUNDAY...AS LOW-LEVEL MOISTURE INCREASES OVER
THE DEEP SNOW PACK.

USED A BLEND OF THE BETTER PERFORMING GUIDANCE SETS FOR MAX/MIN
TEMPS THE NEXT COUPLE DAYS. EXPECT A LARGE TEMPERATURE GRADIENT
TODAY...WITH HIGHS RANGING FROM THE MID TO UPPER 40S OVER THE
SNOW COVERED NORTHWOODS TO THE LOWER TO MIDDLE 60S IN CENTRAL WI.
MILDER MIN TEMPS IN THE 40S ARE EXPECTED TONIGHT...WITH HIGHS IN
THE UPPER 50S TO MIDDLE 60S ON EASTER SUNDAY.

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 341 AM CDT SAT APR 19 2014

THE MEDIUM RANGE MODELS REMAIN IN VERY GOOD AGREEMENT WITH THE LARGE
SCALE FEATURES ACROSS NORTH AMERICA DURING THIS PORTION OF THE
FORECAST.  BY THE END OF THE PERIOD...THE ECMWF IS A LITTLE QUICKER
SHIFTING A CLOSED CYCLONE ACROSS THE REGION.  SINCE THE GFS ENSEMBLE
MEAN IS BETWEEN BOTH MODELS WITH THIS SYSTEM...A GENERAL MODEL
COMPROMISE SHOULD SUFFICE.

SUNDAY NIGHT THROUGH MONDAY NIGHT...STILL A QUESTION MARK WHERE A
WEAK COOL FRONT WILL STALL OUT BY THE START OF SUNDAY NIGHT.  THE
INHERITED FORECAST DEPICTS A BOUNDARY RUNNING FROM WEST-CENTRAL TO
NORTHEAST WISCONSIN AND THE LATEST DATA DOES NOT SUPPORT STRAYING
FROM THIS SCENARIO.  AS A RESULT...FOCUS OF PRECIP WILL OCCUR ALONG
THE FRONT OVER CENTRAL TO NORTHEAST WISCONSIN.  AN UPTICK OF
INTENSITY/COVERAGE IS POSSIBLE SUNDAY NIGHT THANKS TO INCOMING
MID-LEVEL HEIGHT FALLS AHEAD OF SEPARATE PIECES OF SHORTWAVE ENERGY
MOVING ACROSS THE PLAINS.  WILL CONTINUE TO SHOW LIKELY POPS IN THAT
CORRIDOR.  THE STRONGEST PIECE OF ENERGY IN THE NORTHERN STREAM
ARRIVES ON MONDAY AND SHOULD GIVE THE FRONT A GENTLE NUDGE TO THE
EAST OVER THE COURSE OF THE DAY.  STILL THOUGH...THE SOUTHEAST HALF
OF THE FORECAST AREA WILL LIKELY SEE WET WEATHER CONTINUE THROUGH
MUCH OF THE DAY.  THINK MOST OF THE PRECIP WILL HAVE EXITED THE
REGION EXCEPT FOR POSSIBLY THE LAKE SHORE AT THE START OF MONDAY
EVENING.  COLD ADVECTION WILL OCCUR BEHIND THE FRONT...WHICH COULD
LEAD TO A STRATUS DECK DROPPING SOUTHEAST ACROSS THE FORECAST AREA.
WILL SIDE MORE PESSIMISTIC WITH CLOUD COVER.  NO SIGNIFICANT CHANGES
TO TEMPS.

REST OF THE FORECAST...AFTER SOME MORNING CLOUDS ON TUESDAY...SHOULD
SEE INCREASING SUNSHINE AS HIGH PRESSURE MOVES INTO THE REGION.
THIS HIGH PRESSURE WILL HANG AROUND THROUGH WEDNESDAY...WHICH IS NOW
LOOKING LIKE A BETTER CHANCE OF BEING DRY THROUGH THE DAY.  AS A
LARGE WESTERN CONUS TROUGH MOVES INTO THE PLAINS...CHANCES OF PRECIP
WILL INCREASE WEDNESDAY NIGHT.  THE WETTEST PERIOD LOOKS TO BE
THURSDAY INTO THURSDAY NIGHT WHEN SOME THUNDERSTORMS ARE POSSIBLE.
TURNING COOLER AND CONTINUED UNSETTLED ON FRIDAY.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1259 PM CDT SAT APR 19 2014

EXPECT VFR CONDITIONS TO PREVAIL THROUGH AT LEAST EARLY THIS
EVENING...THOUGH A BRIEF SHOWER OR TWO WITH MVFR/IFR CIGS/VSBY IS
NOT TOTALLY OUT OF THE QUESTION AFTER ABOUT 00Z. WINDS INCREASING TO
AROUND 40 KNOTS 1000-1500 FEET OFF THE SURFACE WILL RESULT IN LLWS
ACROSS THE AREA OVERNIGHT. CIGS ARE EXPECTED TO LOWER FROM NORTHWEST
TO SOUTHEAST DURING THE NIGHT. MVFR CIGS AND IFR VSBYS ARE
EXPECTED TO DEVELOP IN LIGHT RAIN AND FOG ACROSS NORTH CENTRAL
WISCONSIN. WEAK SURFACE FLOW WILL COMBINE WITH THE RAIN AND
MELTED SNOW OVER THE REMAINING SNOW PACK TO PRODUCE FOG. CONDITIONS
THERE SHOULD IMPROVE A BIT...TO MVFR CIGS/VSBY...DURING THE
MORNING. MVFR CIGS AND VSBYS SHOULD DEVELOP IN CENTRAL WISCONSIN
LATE TONIGHT/EARLY SUNDAY MORNING AND PERSIST THROUGH 18Z.
CONDITIONS SHOULD BE MAINLY VFR WITH SOME MVFR CIGS/VSBYS...IN
EAST CENTRAL WISCONSIN...DURING THE MORNING ON SUNDAY.
&&

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

$$

UPDATE.........MG
SHORT TERM.....KIECKBUSCH
LONG TERM......MPC
AVIATION.......MG






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