Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 151100
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
600 AM CDT WED APR 15 2015

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND THURSDAY
ISSUED AT 349 AM CDT WED APR 15 2015

THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH
PRESSURE STRETCHING FROM HUDSON BAY TO THE OHIO VALLEY.  LOW LEVEL
WINDS ARE BEGINNING TO SHIFT TO THE EAST OR SOUTHEAST AS THE HIGH
DRIFTS ACROSS THE CENTRAL GREAT LAKES.  DEWPOINTS HAVE RECOVERED
SOMEWHAT...BUT EAGLE RIVER AND ARBOR VITAE HAVE RECENTLY DROPPED
BACK INTO THE TEENS...AND PWATS REMAIN AROUND 0.30 INCHES.  THIN
CIRRUS IS SLOWLY WORKING NORTHWARD AHEAD OF WEAK SHORTWAVES OVER THE
CENTRAL PLAINS AND OHIO VALLEY.  WITH THE VERY DRY AIRMASS
RECIRCULATING OVER THE AREA TODAY...TEMPS/WIND GUSTS/HUMIDITIES
REMAIN THE PRIMARY FORECAST CONCERNS.

TODAY...HIGH PRESSURE OVER THE CENTRAL GREAT LAKES WILL DRIFT SLOWLY
EAST TODAY...BUT STILL REMAIN IN FIRM CONTROL ACROSS THE REGION.
WINDS WILL CONTINUE TO SHIFT TO THE EAST OR SOUTHEAST...EMANATING
OUT OF THIS DRY SURFACE HIGH...AND OFFER NO REPRIEVE FROM THE VERY
DRY CONDITIONS AS OF LATE.  ALTHOUGH MIXING HEIGHTS ARE NOT
PROJECTED TO BE AS HIGH AS YESTERDAY...STRONGER WINDS ALOFT SHOULD
BE ABLE TO TAP INTO THE VERY DRY AIR JUST ABOVE THE INVERSION AND
MIX TO THE SURFACE THIS AFTERNOON.  PROGGED SOUNDINGS INDICATE GUSTS
COULD REACH UP TO AROUND 20 KTS.  THESE GUSTS COMBINED WITH TEMPS IN
THE MID 60S AND HUMIDITIES IN THE MID TEENS WILL RESULT IN A
CRITICAL FIRE WEATHER DAY ACROSS THE REGION.  WITH COORDINATION FROM
SURROUNDING OFFICES AND THE DNR...WILL UPGRADE THE FIRE WEATHER
WATCH INTO A RED FLAG WARNING.  OTHERWISE...CIRRUS WILL GRADUALLY
INVADE FROM THE SOUTH TO OFFER FILTERED SUNSHINE AT TIMES.  TEMPS
WILL BE MUCH COOLER NEAR LAKE MICHIGAN.

TONIGHT...WEAK SHORTWAVE ENERGY WILL LIFT INTO THE WESTERN GREAT
LAKES.  WILL CONTINUE TO SEE A VEIL OF THIN CIRRUS OVERHEAD AS MID
AND LOW LEVELS REMAIN VERY DRY.  DEEPER MOISTURE WILL MAKE A RUN
INTO SOUTHERN LAKE MICHIGAN AND LOWER MICHIGAN...BUT LOOKS TOO FAR
SOUTHEAST TO HAVE MUCH OF AN IMPACT OVER NORTHEAST WISCONSIN.  AS A
RESULT...WILL SEE PARTLY CLOUDY SKIES WITH WARMER LOWS RANGING FROM
THE MIDDLE 30S NORTH TO THE LOW 40S SOUTH.

THURSDAY...DEEP MOISTURE CONTINUES TO FLOW NNE ACROSS THE LOWER
PENINSULA OF MICHIGAN AS A WEAK SHORTWAVE SHIFTS TO THE EAST.
MEANWHILE...A WEAK COLD FRONT WILL SAG INTO MINNESOTA DURING THE
AFTERNOON.  WISCONSIN WILL RESIDE BETWEEN THESE FEATURES WITH AN
AREA OF VERY DRY LOW AND MID LEVEL AIR REMAINING IN PLACE.  THOUGH
THE AIR WILL BE MODIFIED...STILL PLENTY OF DRY AIR TO TAP INTO JUST
ABOVE THE INVERSION BUT WILL NOT HAVE THE GOOD MECHANICAL MIXING
LIKE TODAY.  SO WILL HAVE HUMIDITIES FALLING TO AROUND 25 PCT IN THE
AFTERNOON...WHICH WILL APPROACH CRITICAL LEVELS.  WINDS WILL BE
AROUND 5 TO 10 KTS THOUGH SO NOT EXPECTING A REPEAT OF TODAYS
CRITICAL VALUES.  HIGHS IN THE MID TO UPPER 60S.

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
ISSUED AT 349 AM CDT WED APR 15 2015

ZONAL FLOW EXPECTED EARLY IN THE PERIOD OVER THE GREAT LAKES
REGION AS CUT OFF LOW MEANDERS ACROSS THE SOUTHWEST UNITED
STATES. BY EARLY IN THE WEEKEND...THE CLOSED LOW OVER THE
SOUTHWEST UNITED STATES WILL OPEN UP AND BE PICKED UP BY 500MB
TROUGH MOVING ACROSS SOUTHERN CANADA. THE 500MB TROUGH ACROSS
CANADA WILL EVOLVE INTO A CLOSED LOW ACROSS SOUTHERN CANADA
AND THE WESTERN GREAT LAKES...BRINGING COOLER AND MORE UNSETTLED
WEATHER TO THE REGION.

FOR FRIDAY...ALTHOUGH DEW POINTS WILL BE ON THE INCREASE...SO WILL
TEMPERATURES. AFTERNOON RELATIVE HUMIDITY READINGS SHOULD FALL TO
30 TO 45 PERCENT AT MOST PLACES. FRONTAL BOUNDARY WILL MOVE ACROSS
THE REGION DURING THE DAY...BRINGING A CHANCE OF SHOWERS. MODEL
SOUNDINGS DID SHOW ENOUGH MOISTURE TO SQUEEZE OUT SOME SHOWERS.
IF SHOWERS DO DEVELOP...SOME OF THEM COULD PRODUCE GUSTY WINDS.
MODEL SOUNDINGS INDICATED INVERTED V STRUCTURE TO SUPPORT THE GUSTY
WINDS. COOLER TEMPERATURES WILL RETURN ON SATURDAY ON NORTHEAST/EAST
WINDS. INCREASED MAX TEMPERATURE GRADIENT DUE TO WINDS OFF THE COOLER
BAY AND LAKE...WHILE CENTRAL WISCONSIN COULD STILL REACH THE
MIDDLE 60S. AGAIN...RELATIVE HUMIDITY READINGS AWAY FROM THE BAY AND
LAKE COULD FALL TO 25 TO 35 PERCENT AGAIN.

BASED ON THE LATEST MODEL RUNS TONIGHT...SYSTEM FOR SUNDAY/SUNDAY
NIGHT IS QUICKER THAN LAST NIGHT. DID INCREASE RAIN CHANCES FOR
SUNDAY AFTERNOON WHICH SHOULD LINGER INTO MONDAY. COOLER CYCLONIC
FLOW EARLY NEXT WEEK WILL BRING A SMALL CHANCE OF SHOWERS MONDAY
NIGHT AND TUESDAY.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 600 AM CDT WED APR 15 2015

SOUTHEAST WINDS WILL BECOME GUSTY LATE THIS MORNING THROUGH THE
AFTERNOON.  OTHERWISE...GOOD FLYING WEATHER WILL BE PRESENT INTO
THURSDAY.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM NOON TODAY TO 8 PM CDT THIS EVENING FOR
WIZ030-035>037-045.
&&

$$

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






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