Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 170900
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
400 AM CDT FRI APR 17 2015

FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 400 AM CDT FRI APR 17 2015

THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW A WEAK COLD
FRONT SLOWLY MOVING TO THE SOUTHEAST OVER FAR NORTHWEST WISCONSIN.
AHEAD OF THE FRONT...AREAS OF BROKEN MID-CLOUDS ARE MOVING TO THE
EAST OVER CENTRAL AND NORTHERN WISCONSIN.  CLEAR SKIES EXIST BEHIND
THIS FRONT OVER THE NORTHERN PLAINS.  MEANWHILE...SHOWERS AND
THUNDERSTORMS ARE OCCURRING OVER THE CENTRAL PLAINS AHEAD OF AN
UPPER LOW SPINNING OVER THE 4 CORNERS REGION.  FORECAST CONCERNS
INCLUDE HIGH TEMPS AND LOW HUMIDITIES FOR SATURDAY.

TODAY...THE COLD FRONT WILL SLOW AS IT WEAKENS OVER THE NORTHWEST
THIRD OF THE STATE.  SCATTERED TO BROKEN MID-LEVEL CLOUD DECK WILL
GRADUALLY DISSIPATE THROUGH THE MORNING AS SUBSIDENCE STRENGTHENS
OVERHEAD.  WILL STILL BE SOME RESIDUAL MOISTURE LEFT AROUND
800MB...HOWEVER...THAT WILL TURN INTO A CU FIELD BY LATE MORNING
OVER CENTRAL TO NORTHEAST WISCONSIN.  FAR NORTHERN WISCONSIN WILL
SEE AN INFLUX OF DRIER AIR DURING THE AFTERNOON...WHICH WILL DROP
HUMIDITIES INTO THE 20 TO 25 PCT RANGE.  HUMIDITIES SHOULD BE ABOVE
CRITICAL CRITERIA ELSEWHERE.  RAISED HIGH TEMPS BASED ON 925MB TEMPS
ON THE BETTER PERFORMING NAM AND ECMWF...AND MAY NOT BE HIGH
ENOUGH.  TEMPS TO MAX OUT TO NEAR 70 NORTH TO THE UPPER 70S IN THE
WARM SPOTS.

TONIGHT...THE WEAKENING FRONT WILL DROP ACROSS CENTRAL AND
NORTHEAST WISCONSIN DURING THE EVENING WHILE A SECONDARY AND MORE
POTENT FRONT QUICKLY MOVES SOUTH ACROSS NORTHERN AND CENTRAL
WISCONSIN AFTER MIDNIGHT.  BEHIND THE SECOND FRONT...WINDS WILL
SHIFT TO THE NORTHEAST AND COULD GUST FOR A COUPLE HOURS TO 20 OR 25
MPH.  TEMPS WILL ALSO COOL OFF QUICKLY BEHIND THE FRONT WITH LOWS
FALLING INTO THE MIDDLE 30S NORTH TO THE MIDDLE 40S SOUTH.

SATURDAY...CANADIAN HIGH PRESSURE WILL BUILD SOUTHEAST ACROSS THE
CENTRAL GREAT LAKES.  THE AIRMASS ASSOCIATED WITH THIS SURFACE HIGH
IS EXCEPTIONALLY DRY (NAM 850-700MB RH FALLS TO 2 PCT!).  THOUGH
HIGH CLOUDS WILL BE ON THE INCREASE DURING THE AFTERNOON AHEAD OF
THE CENTRAL ROCKIES UPPER LOW...SHOULD STILL SEE PLENTY OF SUNSHINE
ALBEIT WITH COOLER TEMPERATURES.  CRITICAL RELATIVE HUMIDITIES
BETWEEN 15 TO 25 PCT WILL STILL OCCUR THOUGH NORTH AND WEST OF THE
FOX VALLEY.  POTENTIAL IS THERE FOR HUMIDITIES TO FALL LOWER THAN
THIS IF TAPPING OCCURS INTO THIS BONE DRY AIR ALOFT.  HIGHS MAINLY
IN THE LOW TO MID 60S AWAY FROM LAKE MICHIGAN.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 400 AM CDT FRI APR 17 2015

500MB OPEN TROUGH WILL EVOLVE INTO A CLOSED LOW OVER THE WESTERN
GREAT LAKES REGION BY EARLY NEXT WEEK. COOL CYCLONIC FLOW WILL
CONTINUE FOR THE REMAINDER OF NEXT WEEK AS THE 500MB LOW MEANDERS
ACROSS THE GREAT LAKES REGION/EASTERN CANADA.

MODELS IN SOMEWHAT BETTER AGREEMENT TONIGHT BRINGING THE BEST
CHANCE FOR RAIN SUNDAY INTO SUNDAY NIGHT. WILL CONTINUE A SMALL
CHANCE OF SHOWERS AFTER MIDNIGHT ON SATURDAY NIGHT TO ACCOUNT FOR
A SLIGHTLY QUICKER ARRIVAL THAT SOME OF THE MODELS ARE DEPICTING.
WILL HAVE LIKELY OR LOW END CATEGORICAL CHANCES FOR RAIN ON SUNDAY.
HIGH TEMPERATURES TRICKY DEPENDING ON QUICK THE STEADIER RAINS
ARRIVE. IF RAIN ARRIVES EARLY IN THE DAY SUNDAY...HIGH TEMPERATURES
WILL NEED TO BE LOWERED. COUNTING ON SOME DRY ON BACKSIDE OF THE
RETREATING HIGH PRESSURE SYSTEM TO SLOW THE ARRIVAL OF THE RAIN
ACROSS EASTERN WISCONSIN.

OTHERWISE...BELOW NORMAL TEMPERATURES ARE EXPECTED FOR MUCH OF THE
WEEK WITH CHANCES OF RAIN INTO THE MIDDLE OF NEXT WEEK. STILL HAVE
A CHANCE OF SNOW LATE AT NIGHT OR EARLY IN THE DAY FOR EACH PERIOD
FROM MONDAY NIGHT THROUGH WEDNESDAY. BY THURSDAY...UPPER LOW MAY BE
FAR ENOUGH AWAY FOR JUST A SMALL CHANCE OF RAIN ACROSS THE FAR NORTH.
PREVIOUS FORECAST TEMPERATURES SEEMED REASONABLE WITH ONLY MINOR CHANGES
MADE IN SOME PERIODS.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1048 PM CDT THU APR 16 2015

VFR CONDITIONS EXPECTED TONIGHT INTO FRIDAY. A FRONTAL BOUNDARY
WILL DROP SOUTHEASTWARD OVER THE STATE TONIGHT INTO FRIDAY
MORNING. SINCE THE AIR MASS IS DRY...EXPECT A BAND OF MID LEVEL
CLOUDS TO BE ASSOCIATED WITH THE FRONT. LIGHT SOUTHWEST WINDS
SHIFTING NORTHWEST WILL MARK THE FRONTS PASSAGE. LATER
FRIDAY MORNING...DEEP MIXING MAY PRODUCE A WEST WIND OF 5 TO 10 MPH
WHILE WINDS TURN NORTHEAST TO EAST ALONG LAKE MICHIGAN FRIDAY
AFTERNOON.
&&

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

$$

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





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