Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 260001
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
701 PM CDT MON AUG 25 2014

UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 242 PM CDT MON AUG 25 2014

THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW AN OCCLUDED
LOW PRESSURE OVER LAKE WINNIPEG AND A COLD FRONT SLICING ACROSS
WESTERN LAKE SUPERIOR AND WISCONSIN FROM ABOUT HAYWARD TO LA
CROSSE.  AHEAD OF THE FRONT...THE ATMOSPHERE HAS BEEN VERY SLOW TO
DESTABILIZE AS TEMPERATURES REMAIN IN THE UPPER 70S TO LOWER 80S.
STARTING TO SEE SOME MIDDLE 80S POP UP OVER WEST-CENTRAL WISCONSIN
WHERE ML CAPES ARE RISING TO ABOUT 1200 J/KG.  STILL SEVERAL MORE
HOURS OF HEATING TO GO THOUGH ESPECIALLY OVER CENTRAL AND EASTERN
WISCONSIN WHERE CONVECTIVE DEBRIS CONTINUES TO HOVER OVERHEAD.
BECAUSE OF THE SLOWER HEATING SO FAR...HAVE REDUCED THE CHANCES OF
SHOWERS AND THUNDERSTORMS FOR THE REST OF THE AFTERNOON INTO THE
ISOLATED RANGE AFTER 21Z.  AS THE FRONT MOVES THROUGH...SHOWER AND
THUNDERSTORM CHANCES ARE THE MAIN FORECAST CONCERN.

TONIGHT...THE COLD FRONT WILL SLOWLY SLIDE SOUTHEAST ACROSS
NORTHEAST AND EAST-CENTRAL WISCONSIN DURING THE EVENING BEFORE
EXITING THE LAKE MICHIGAN SHORELINE AROUND 06-08Z.  AHEAD OF THE
FRONT...WILL LEAVE AN ISOLATED MENTION OF SHOWERS AND THUNDERSTORMS
OVER NORTHEAST AND EAST-CENTRAL WISCONSIN UNTIL THE FRONT CLEARS THE
AREA.  IF TEMPS CAN RISE INTO MIDDLE 80S AHEAD OF THE FRONT...WHICH
SEEMS REASONABLE...ANY STORMS THAT DEVELOP COULD BECOME STRONG AND
PRODUCE STRONG GUSTY WINDS AND HAIL.  HOWEVER...THE MESO MODELS ARE
EXTREMELY BEARISH IN PREDICTING THUNDERSTORMS THIS AFTERNOON.  AND
WITH THE SLOW DESTABILIZATION SO FAR TODAY...HAVE LOWERED THE
CHANCES OF STORMS.  AS INSTABILITY IS LOST THIS EVENING...INTENSITY
OF ANY STORMS SHOULD WANE QUICKLY BY MID-EVENING.  COOLER AND DRIER
AIR WILL GRADUALLY MAKE INROADS ACROSS THE FORECAST AREA BEHIND THE
FRONT...BUT WARM AND MUGGY CONDITIONS SHOULD HANG ON FOR MUCH OF THE
NIGHT ACROSS THE EAST.  LOWS RANGING FROM THE MIDDLE 50S NORTH TO
MIDDLE 60S SOUTHEAST.

TUESDAY...THE COLD FRONT WILL CONTINUE TO MOVE SOUTH OVER SOUTHEAST
WISCONSIN AND NORTHERN ILLINOIS WHILE CANADIAN HIGH PRESSURE MOVES
INTO THE NORTHWEST GREAT LAKES.  MOST AREAS WILL SEE A GOOD DEAL OF
SUNSHINE...THOUGH CU MAY BE A LITTLE MORE PREVALENT OVER N-C
WISCONSIN WHILE HIGH CLOUDS WILL LIKELY REMAIN OVERHEAD OVER CENTRAL
AND EAST-CENTRAL WISCONSIN.  TEMPS AND HUMIDITY LEVELS WILL BE
SIGNIFICANTLY LOWER THAN TODAYS READINGS...AND WILL GO WITH HIGHS IN
THE LOWER 70S NORTH TO THE UPPER 70S SOUTH.

.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 242 PM CDT MON AUG 25 2014

CONTINUED WITH SAME TRENDS OF FORECAST AS MODELS CONTINUE TO SHOW
A PROGRESSIVE NORTHERN STREAM ALONG THE U.S. AND CANADIAN BORDER
THRU THE END OF THE WEEK. WILL BE DEALING WITH ENERGY MOVING
THROUGH THE NORTHERN STREAM AND WEAK CUT OFF TROF MEANDERING OUT
OF THE WEST...THROUGH THE CENTRAL PLAINS.

TUE NIGHT THROUGH THU...EARLY IN PERIOD...SHORT WAVE TO MOVE OUT
OF NORTHERN PLAINS INTO WESTERN LAKES. AT THE SURFACE DRIER AIR
WITH SURFACE HIGH IN PLACE OVER NORTHERN HALF OF WI WITH FRONT SHOVED
SOUTH INTO NORTHERN IL. HAVE CONTINUED DRY FORECAST FROM PREVIOUS
SHIFT...BUT PAST TWO RUNS OF EC SHOWING LIGHT PCPN BREAKING OUT
OVER THE NORTH ALONG 850 FRONT. LATER SHIFT CAN REVIEW BUT FOR NOW
KEPT DRY. MEANDERING TROF BEGINS TO MOVE INTO CENTRAL PLAINS BY THU.
OLD FRONT TO BEGIN TO MAKE WAY NORTH. MODELS SUGGEST CONVECTIVE
COMPLEX DEVELOPING MN/WESTERN WI AS 850 FLOW INCREASES OVER FRONT.
GFS AND NAM FURTHER NORTH WITH COMPLEX THAN CANADIAN AND EC. SREF
TENDING TO SUPPORT FURTHER SOUTH LOOK. HAVE STAYED CLOSE TO
PREVIOUS FORECAST WITH CHANCE POPS DURING DAY ON THU.

UNSETTLED WEATHER TO THEN PERSIST THROUGH THE END OF THE FORECAST
AS MORE ENERGY MOVES THROUGH CANADA.

TEMPERATURES EXPECTED TO RUN NEAR OR A BIT BELOW NORMAL THROUGH
MUCH OF THE PERIOD.
&&

.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 657 PM CDT MON AUG 25 2014

VFR CONDITIONS WILL PREVAIL TONIGHT AND TUESDAY ACROSS THE REGION AS
HIGH PRESSURE DOMINATES THE REGION. SOUTH/SOUTHWEST WINDS WILL VEER
WEST AND THEN WEST OR NORTHWEST OVERNIGHT THROUGH MUCH OF TUESDAY.
MAIN QUESTION AT THE KMTW SITE IS WHEN A LAKE BREEZE WILL KICK IN.
HAVE FIGURED 22Z FOR NOW THINKING GRADIENT WINDS MAY DELAY SHIFT
TO THE SOUTHEAST...HOWEVER CONFIDENCE IS LOW ON THE TIMING OF THIS
EVENING.

&&

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

$$

SHORT TERM.....MPC
LONG TERM......TE
AVIATION.......ECKBERG






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