Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 162046
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
346 PM CDT SAT AUG 16 2014

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 346 PM CDT SAT AUG 16 2014

MAIN CONCERNS IN THE SHORT TERM ARE SHOWERS AND THUNDERSTORMS AND
FOG POTENTIAL LATER TONIGHT.

SHOWERS INCREASED AND THUNDERSTORMS DEVELOPED DURING THE DAY AS
MUCAPE VALUES INCREASED TO MORE THAN 1000J/KG OVER MUCH OF THE
AREA BY MID AFTERNOON. ACTIVITY WAS SOUTH OF A COLD FRONT THAT WAS
MOVING VERY SLOWLY TO THE SOUTH TODAY. EXPECT SHOWERS AND STORMS
TO EXIT THE FORECAST AREA DURING THE NIGHT AS THE FRONT CONTINUES
SOUTHWARD. STRATUS CLEARED OUT ACROSS WESTERN ONTARIO DURING THE
DAY SO AMOUNT OF CLEARING TONIGHT IS IN QUESTION. THE NORTHERN
PART OF THE FORECAST AREA WOULD BE THE MOST LIKELY LOCATION FOR
CLEARING...AND THERE WAS SOME SIGNIFICANT RAINFALL THERE TOO.
THESE FACTORS COMBINED WITH LIGHT WINDS SHOULD BE FAVORABLE FOR
FOG FORMATION...WITH AT LEAST PATCHY DENSE FOG.

EXPECT LOWS IN THE MIDDLE AND UPPER 40S ACROSS MUCH OF NORTHERN
WISCONSIN...EVEN THOUGH DEW POINTS WERE IN THE 60S AT 20Z. LOWS
SHOULD BE IN THE MIDDLE AND UPPER 50S IN CENTRAL AND EAST CENTRAL
WISCONSIN. HIGHS ON SUNDAY ARE EXPECTED TO BE AROUND OR SLIGHTLY
BELOW NORMAL FOR THIS TIME OF YEAR. EAST WINDS WILL KEEP IT RATHER
COOL NEAR LAKE MICHIGAN.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 346 PM CDT SAT AUG 16 2014

MEDIUM RANGE MODELS FORECAST AN UPPER TROUGH TO MOVE
FROM LAKE WINNIPEG INTO MINNESOTA MONDAY AND THEN FOR THE TROUGH
TO CLOSE OFF AS AN UPPER LOW OVER WISCONSIN TUESDAY. UPPER
DIFFLUENCE COMBINED WITH LOW LEVEL WARM ADVECTION AND CONVERGENCE
SHOULD PROVIDE AMPLE SUPPORT FOR SHOWERS AND THUNDERSTORMS. THE
QUESTION IS WHEHER THERE MIGHT BE ANY SEVERE STORMS. FOR THE LAST
COUPLE OF DAYS THE SAINT LOUIS UNIVERSITY METEOROLOGY DEPARTMENTS
CASE STUDIES COMPARISON PAGE HAS SUGGESTED THAT TUESDAYS SURFACE
AND UPPER AIR PATTERN CORRELATES TO PAST SEVERE WEATHER OUTBREAKS
BUT HAS BACKED OFF SOMEWHAT TODAY. THERE DOES NOT SEEM TO BE
ENOUGH WIND SHEAR WITH THE UPPER LOW PASSING RIGHT OVER WISCONSIN
AND INSTABILITY MAY BE LACKING DUE TO CLOUD COVER AND PRECIPITATION.
SLOW MOVING STORMS COULD PRODUCE TORRENTIAL RAINS THOUGH.

THERE SHOULD BE SOME DRYING DURING THE MIDDLE OF THE WEEK AS WEAK
UPPER RIDGING ARRIVES BUT WE WILL PROBABLY BE CLOSE TO A SURFACE
BOUNDARY MUCH OF THE TIME.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 108 PM CDT SAT AUG 16 2014

SHOWERS WERE INCREASING AHEAD OF A COLD FRONT THAT WAS SLOWLY
MOVING TO THE SOUTH OUT OF UPPER MICHIGAN. MESOANALYSIS INDICATED
INCREASING INSTABILITY ACROSS THE AREA AND RADAR TIME LAPSE SHOWED
AN INCREASE IN SHOWERS...WITH SOME OF THE STRONGER ECHOES PROBABLY
CONTAINING AT LEAST ICCC LIGHTNING IF NOT CG. RHI HAS HAD SHOWERS
BUT MOST OF THE ACTIVITY HAS BEEN NORTH OF THE REMAINDER OF THE
TAF SITES...WITH ONLY SOME SPRINKLES OR BRIEF LIGHT SHOWERS AT
GRB. MVFR CIGS WERE FAIRLY WIDESPREAD AND THERE WERE ALSO SOME IFR
CIGS ACROSS NORTHERN WISCONSIN. SHOWERS AND THUNDERSTORMS SHOULD
CONTINUE ALONG AND AHEAD OF THE FRONT AS IT MOVES SOUTH...WITH
MAINLY MVFR CIGS. VSBYS WITH SHOWERS AND STORMS WILL BE MAINLY
MVFR AND OCCASIONALLY IFR IN HEAVIER RAINFALL. THINK LOW CLOUDS
AND FOG WILL BE AN ISSUE OVERNIGHT...WITH CONDITIONS IMPROVING
DURING THE MORNING.
&&

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

$$

SHORT TERM.....MG
LONG TERM......RDM
AVIATION.......MG





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