Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 262009
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
309 PM CDT TUE AUG 26 2014

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND WEDNESDAY
ISSUED AT 309 PM CDT TUE AUG 26 2014

UPPER LEVEL FLOW STARTS OUT PRETTY MUCH ZONAL AT THE START OF THE
PERIOD AND THEN BEGINS TO AMPLIFY LATER TONIGHT. THE CONCERN FOR
TONIGHT IS A SHORT WAVE THAT WILL PASS ACROSS NORTHERN
WISCONSIN. MOISTURE IS LIMITED AND HIGH PRESSURE WILL BE THE MAIN
SURFACE FEATURE. HOWEVER...THE 12Z GFS AND 12Z NAM HAD QPF IN
NORTHERN WISCONSIN AND THE 12Z ECMWF HAD QPF THAT WAS EVEN MORE
WIDESPREAD. HAVE A SLIGHT CHANCE FOR SHOWERS AND A CHANCE FOR
SPRINKLES MENTIONED LATE TONIGHT IN THE NORTH TO ACCOUNT FOR THIS.

DEW POINTS IN THE 40S AND 50S...ALONG WITH MOSTLY CLEAR/PARTLY
CLOUDY SKIES DURING THE EVENING SHOULD ALLOW TEMPERATURES TO FALL
TO NEAR NORMAL LOWS FOR THIS TIME OF YEAR. LOOKS LIKE SLIGHTLY
BELOW NORMAL TEMPERATURES ON WEDNESDAY.

.LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY
ISSUED AT 309 PM CDT TUE AUG 26 2014

MEAN FLOW THRU THIS PERIOD TO BE PROGRESSIVE WITH WESTERLIES LYING ALONG
U.S./CANADIAN BORDER. A WEAK CUT-OFF UPPER TROF DRIFTING EAST OUT
OF THE ROCKIES WILL BE EVENTUALLY BROUGHT EAST BY SUCCESSIVE SHORT
WAVES MOVING THROUGH WESTERLIES. PCPN CHANCES MAIN ISSUE THIS
PERIOD WITH MODELS POINTING AT A RATHER WET PERIOD LATER THU INTO
SATURDAY. (SEE HYDROLOGY SECTION) A SHORT BREAK EXPECTED SUNDAY...BEFORE
STRONGER SYSTEM MOVES THROUGH ON MONDAY.

SURFACE HI SHIFTS EAST OF THE AREA WED NIGHT LEADING TO INCREASING MOISTURE
WITH FRONT SLOWLY RETURNING NORTH. PW VALUES TO AGAIN BE UP IN
THE 1.5-2.0" RANGE. HAVE TRENDED TOWARD EC`S MORE CONSISTENT...
SOUTHERLY TRENDS REGARDING PCPN COVERAGE. HIGHEST POPS OVER CENTRAL
AND EAST CENTRAL CWA. DIFFERENCES THIS PERIOD VERSUS EARLIER THIS
WEEK...LESS SURFACE BASED INSTABILITY BUT BETTER DYNAMICS WITH
FRONT/WAVE LIFTING NORTH INTO SOUTHERN CWA AND SUPPORT OF JET ALOFT.
TEMPERATURES TO BE TRICKY DEPENDENT ON CLOUDS AND PCPN...THUS MADE LITTLE
CHANGE TO PREVIOUS FORECAST PACKAGE.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 105 PM CDT TUE AUG 26 2014

SCATTERED TO BROKEN 2000-3000FT AGL CLOUDS COVERED THE NORTHERN
AND EASTERN PARTS OF THE FORECAST AREA AT MIDDAY AND THERE WERE
ALSO SOME MID AND HIGH CLOUDS. ANY MVFR CIGS SHOULD GRADUALLY COME
TO AN END THIS AFTERNOON...WITH MAINLY VFR CONDITIONS LIKELY TO
PREVAIL THROUGH THE END OF THE TAF VALID PERIOD. MODELS WERE
SHOWING SOME PRECIPITATION WITH A SHORT WAVE PASSING ACROSS
NORTHERN WISCONSIN SO THERE WILL PROBABLY BE SOME SHOWERS IN THE
NORTH OVERNIGHT. SOME OF THE HEAVIER SHOWERS COULD REDUCE VSBYS
INTO THE MVFR RANGE. SHOWERS SHOULD BE OUT OF THE AREA BY EARLY
WEDNESDAY.
&&

.HYDROLOGY...
ISSUED AT 309 PM CDT TUE AUG 26 2014

PWATS WILL BE ON THE INCREASE THURSDAY REACHING 1.5
TO 2.0 INCHES OVER WISCONSIN. SIG SOUTHERLY LOW LEVEL FLOW OVER
WARM FRONT LIFTING NORTH THURSDAY WILL BRING A POTENTIAL OF HEAVY
RAIN TO CENTRAL WI THU AFTERNOON. SURFACE WAVE AND WARM FRONT EXPECTED TO
LIFT NORTH INTO PARTS OF CENTRAL AND EAST CENTRAL WI LATER THU
NIGHT INTO FRI CONTINUING HEAVY RAIN POTENTIAL FOR CENTRAL AND
EAST CENTRAL WI. MODELS SUGGEST RRQ REGION OF THE UPPER JET MAY
ADD TO THE SUPPORT FOR HEAVY RAIN EVENT THIS PERIOD. RIVER LEVELS ARE
NEAR NORMAL AND CAN HANDLE A FEW INCHES OF RAIN...FLOODING
CONCERNS WOULD PRIMARILY BE SMALL STREAM AND URBAN AREAS AT THIS
TIME.
&&

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

$$

SHORT TERM.....MG
LONG TERM......TE
AVIATION.......MG
HYDROLOGY......TE






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