Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 121123 AAA
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
623 AM CDT SAT APR 12 2014

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 343 AM CDT SAT APR 12 2014

RAIN WILL CONTINUE TO DEVELOP AND SPREAD INTO THE STATE THIS
MORNING DUE TO THE WAA RETURN FLOW ON A 50 KNOT LLJ. RADAR SHOWS
THE MAIN BAND OF RAIN ALONG AND NORTH OF THE H850 WARM FRONT
LIFTING SPREADING FROM NORTHWEST WISCONSIN EASTWARD INTO THE REST
OF NORTHERN WISCONSIN. TSTMS NOTED ALONG A SECOND CLUSTER OF
CONVECTION FROM EASTERN SD TO CENTRAL IOWA...WHICH IS NEAR THE
SURFACE WARM FRONT AND LOCATION OF DEEPER MOISTURE. ANTICIPATE
PCPN WILL BE MORE BANDED AND ON THE LIGHT SIDE DUE TO THE DRY
AIRMASS AT THE ONSET. PWATS CLIMB FROM 0.40 EARLY THIS MORNING TO
0.60 ACROSS THE NORTH TO AROUND AN INCH OVER CENTRAL AND EAST
CENTRAL WISCONSIN LATE THIS AFTERNOON SO RAIN RATES WILL
INCREASE. MORNING TEMPS ACROSS THE FAR NORTH AND NORTHEAST IN THE
UPPER 20S TO AROUND 30...WILL CONTINUE THE EARLY MORNING MIX
ACROSS THE NORTH UNTIL THE WAA TURNS TO ALL RAIN. UP TO A HALF
INCH OF RAIN IS POSSIBLE FOR MOST LOCATIONS TODAY WITH THIS
INITIAL PCPN.

ANTICIPATE PCPN TO DIMINISH FROM THE NORTHWEST LATE THIS
AFTERNOON OR EVENING WITH THE END OF THE WAA. BUT SHOWER ACTIVITY
WILL LIKELY LINGER ALONG OR NEAR THE SURFACE AND H8 BOUNDARY
STRETCHING FROM FAR EASTERN WISCONSIN TO EASTERN IOWA. RAINFALL
AMOUNTS ARE EXPECTED TO BE AROUND A HALF INCH FOR AREAS SOUTHEAST
OF A MTW TO OSH LINE BUT THEN GREATLY REDUCED FOR AREAS NORTHWEST
OF THIS LINE.

THE BOUNDARY OVER THE SOUTHEAST THIRD OF THE STATE WILL REMAIN
THE FOCUS OF ADDITIONAL RAINFALL ON SUNDAY AS A BROAD COUPLED
UPPER JET PATTERN DEVELOPS DRIFTS OVER THE AREA AND FGEN FORCING
INCREASES AS COLDER AIR FROM THE NORTHWEST SAGS INTO THE AREA. A
SURFACE WAVE BEGINS TO TRACK OVER NORTHEAST IL OR FAR SOUTHEAST WI
ON SUNDAY.

GUID MAX TEMPS HAVE TRENDED LOWER TODAY OVER PARTS OF THE NORTH
AND NORTHEAST WHICH APPEARS REASONABLE WITH THE LOW SURFACE
DEWPOINTS AND RAIN SPREADING INTO THE AREA.

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 343 AM CDT SAT APR 12 2014

THE MAIN CONCERNS DURING THIS PART OF THE FORECAST ARE WITH PRECIPITATION
DURING THE EARLY PART OF NEXT WEEK...ITS AMOUNT AND TIMING OF THE
CHANGEOVER FROM RAIN TO SNOW BEFORE IT ENDS.

COLD AIR WRAPPING AROUND A SURFACE LOW PASSING SOUTHEAST OF THE
FORECAST AREA WILL CAUSE RAIN TO CHANGE TO SNOW FROM NORTHWEST TO
SOUTHEAST ON SUNDAY NIGHT...BEFORE THE PRECIPITATION DEPARTS.
MODELS HAD HIGHEST QPF ACROSS THE SOUTHEAST PART OF THE FORECAST
AREA WHERE THE CHANGE TO SNOW WILL OCCUR THE LATEST. SNOW TOTALS
SHOULD TOP OUT AT NO MORE THAN 2 INCHES SINCE QPF IS LOWER IN THE
COLDER AIR...AND LOCATIONS WHERE QPF IS HIGHER WILL TAKE THE
LONGEST TO CHANGE TO SNOW. KEPT SOME SNOW ON MONDAY...MAINLY FOR
THE EARLY MORNING HOURS...WITH LITTLE OR NO ADDITIONAL
ACCUMULATION.

LITTLE CONFIDENCE IN WHAT IS GOING TO HAPPEN LATER IN THE WEEK DUE
TO SIGNIFICANT DIFFERENCES AMONG THE MODELS. HAVE KEPT WITH THE BLEND
OF MODEL SOLUTIONS FOR THE REST OF NEXT WEEK. THIS RESULTED IN
SLIGHT CHANCE OR CHANCE POPS FOR PRETTY MUCH EVERY PERIOD DURING
THE LATTER HALF OF THE WEEK.

TEMPERATURES SHOULD BE BELOW NORMAL THROUGHOUT THE
PERIOD...ESPECIALLY ON MONDAY AND TUESDAY. AFTER THAT...THERE SHOULD
BE A BIT OF A WARM UP BUT HIGHS WILL STILL BE 5 TO 10 DEGREES BELOW
NORMAL.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 622 AM CDT SAT APR 12 2014

VFR CONDITIONS EARLY THIS MORNING ARE EXPECTED TO
DETERIORATE TO IFR CRITERIA FROM NORTHWEST TO SOUTHEAST AS A LOW
PRESSURE SYSTEM SLIDES OVER THE STATE. THERE IS A CHANCE FOR
THUNDERSTORMS FIRST OVER CENTRAL WISCONSIN LATE MORNING AND THEN
THE REST OF THE AREA THIS AFTERNOON AND EVENING.
&&

.HYDROLOGY...
ISSUED AT 416 AM CDT SAT APR 12 2014

CURRENT FCST QPF FOR THE PERIOD FROM TODAY THROUGH SUNDAY EVENING
RANGES FROM AROUND A HALF INCH ACROSS NORTH CENTRAL WISCONSIN TO 1
TO 2 INCHES SOUTH OF LINE FROM MARINETTE TO SHAWANO TO WISCONSIN
RAPIDS...WITH THE HIGHER ALMOST 2 INCH AMOUNTS OVER WINNEBAGO TO
CALUMET TO MANITOWOC COUNTIES. THIS REGION OF OF HIGHER FORECAST
RAIN AMOUNTS ALSO OVER AN AREA WHICH LOSS THE SNOW COVER FOR A
WHILE NOW AND RIVERS HAVE DROPPED...WHICH IS SIMILAR TO SOUTHERN
WISCONSIN WHERE EVEN HIGHER RAINFALL IS ANTICIPATED. ACTUALLY
COULD USE SOME RAIN NOW. BUT THIS 1-2 INCHES WILL FALL IN A 36-42
HOUR PERIOD AND MAY HAVE BREAKS IN THE RAIN. FFG NUMBERS ARE
AROUND 2 INCHES FOR A 6 HOUR PERIOD OVER PARTS OF THIS REGION.
CONSIDERED AN AREAL FLOOD WATCH...BUT CONFIDENCE NOT ENOUGH. LATER
SHIFTS MAY NEED TO ADDRESS FLOODING CONCERNS WITH RIVER TYPE
STATEMENTS AND POSSIBLY URBAN SMALL STREAM ADVISORIES IF TRAINING
STORMS BECOME AN ISSUE.

ANTICIPATED RAINFALL OVER THE WISCONSIN RIVER BASIN WILL LIKELY
JUST MAINTAIN CURRENT LEVELS THROUGH THIS WEEKEND AND ALREADY
HANDLING THIS MINOR FLOODING ISSUE WITH VARIOUS HYDRO STATEMENTS.
OVERALL...IF THIS RAINFALL REMAINS SOUTH OF THE LINE MENTIONED
ABOVE...WE SHOULD AVOID ANY SIGNIFICANT FLOODING FOR THE
WISCONSIN RIVER THIS WEEKEND. COLDER TEMPERATURES THEN ARRIVE FOR
THE START OF THE NEW WORK WEEK.
&&

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

$$

SHORT TERM.....TDH
LONG TERM......MG
AVIATION.......TDH
HYDROLOGY......TDH






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