Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 280812
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
312 AM CDT SUN JUN 28 2015

FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND MONDAY
ISSUED AT 312 AM CDT SUN JUN 28 2015

SHOWERS AND THUNDERSTORMS FROM AN APPROACHING LOW CONTINUE TO
SLOWLY TRACK EAST DURING THE EARLY MORNING HOURS. DESPITE THIS
STEADY MARCH EASTWARD THE SHORTWAVE ASSOCIATED WITH THIS ACTIVITY
IS PROGGED TO DIVE SOUTHEAST DURING THE DAY...TRACKING ALONG THE
WESTERN WISCONSIN BORDER TODAY BEFORE TURNING EAST AND TRACKING
THROUGH NORTHERN ILLINOIS TONIGHT. THE TRACK OF THE MID LEVEL
SHORTWAVE IS NOT REALLY CONDUCIVE FOR PRECIPITATION MAKING IT
THAT FAR EAST. IN FACT AREAS EAST OF THE FOX VALLEY MAY NOT SEE
ANY RAIN AT ALL TODAY. THE BEST CHANCE FOR RAIN WILL BE OVER
CENTRAL WISCONSIN CLOSER TO THE SHORTWAVE ENERGY AND FARTHER AWAY
FROM THE FEED OF DRY AIR AFFORDED BY HIGH PRESSURE OFF TO THE
EAST. IN THIS REGARD THE FORECAST REMAINS LARGELY UNCHANGED FROM
THE PREVIOUS SHIFT AS THE FORECAST ALREADY ECHOES THESE THOUGHTS.
HIGHS THIS AFTERNOON WILL RANGE FROM THE LOWER TO MIDDLE 70S OUT
TO THE WEST WITH THE ABUNDANT CLOUD COVER AND RAIN...WITH HIGHS
AROUND 80 OUT TO THE EAST AWAY FROM LAKE MICHIGAN GIVEN THE LONGER
PERIOD OF TIME IN THE SUNSHINE.

AS THE SHORTWAVE TRACKS THROUGH NORTHERN ILLINOIS TONIGHT RAIN
CHANCES WILL DIMINISH PRECIPITOUSLY WITH VERY LITTLE CHANCE FOR
RAIN AFTER MIDNIGHT. ABUNDANT CLOUD COVER SHOULD KEEP LOWS IN THE
MIDDLE TO UPPER 50S. MODEST INSTABILITY VALUES AND UPSTREAM
OBSERVATIONS CERTAINLY WARRANT THE INCLUSION OF THUNDER TODAY AND
TONIGHT...HOWEVER ORGANIZED STORMS ARE NOT EXPECTED GIVEN THE WEAK
SHEAR AND MODEST INSTABILITY.

ANOTHER SHORTWAVE WILL TRACK THROUGH THE WESTERN GREAT LAKES ON
MONDAY...PROVIDING A BETTER CHANCE FOR WIDESPREAD SHOWERS AND
THUNDERSTORMS AS MUCAPE VALUES RISE TO 1000 TO 1500 J/KG DURING
THE AFTERNOON HOURS WITH AFTERNOON HIGHS IN THE MIDDLE TO UPPER
70S. ALTHOUGH SHEAR VALUES WILL STILL BE MODEST...AS EVIDENCED BY
0-6 KM BULK SHEAR VALUES OF 20 TO 25 KNOTS...THE MUCAPE VALUES
SUGGEST A STRONG STORM IS NOT OUT OF THE QUESTION.

.LONG TERM...MONDAY NIGHT THROUGH SATURDAY
ISSUED AT 312 AM CDT SUN JUN 28 2015

AN AMPLIFIED FLOW ALOFT IS FCST TO PERSIST ACROSS THE CONUS THRU
THE END OF THE WEEK. AN UPR RDG IS EXPECTED TO DRIFT WEST TOWARD
WRN NOAM...WHILE A DOWNSTREAM UPR TROF TO PREVAIL ACROSS THE ERN
CONUS. FOR NE WI...THIS LEAVES A NW FLOW ALOFT OVERHEAD WITH A
SERIES OF MID-LEVEL DISTURBANCES HEADED TOWARD THE BASE OF THE UPR
TROF. TEMPS WL BE BELOW NORMAL THRU THE PERIOD WITH SEVERAL
OPPORTUNITIES FOR PCPN WITH THE PASSAGE OF EACH DISTURBANCE.

EVEN WITH THE UPR TROF RESIDING OVER THE GREAT LAKES MON NGT...THE
LOSS OF DAYTIME HEATING WL DIMINISH INSTABILITY...THUS ALLOWING
SHWR/ISOLATED TSTM ACTIVITY TO DECREASE IN COVERAGE THRU THE NGT.
ANTICIPATE MOSTLY CLOUDY SKIES...LIGHT WINDS AND DEW POINTS IN THE
50S. THIS COULD ALLOW FOR PATCHY LATE NGT FOG TO DEVELOP ONCE
AGAIN. LOOK FOR MIN TEMPS TO RANGE FROM THE LWR TO MID 50S
NORTH...55-60 DEG RANGE SOUTH.

THE CORE OF THE UPR TROF SHIFTS EWD ON TUE WITH A WEAKENING
CYCLONIC FLOW OVER THE ERN HALF OF WI. MEANWHILE...A WEAK AREA OF
HI PRES IS FCST TO START BUILDING SWD FROM WRN ONTARIO. TUE`S FCST
WL COME DOWN TO HOW FAST THE TROF PULLS EAST AND HOW FAST THE SFC
HI BUILDS SOUTH. ERN WI REMAINS THE MOST SUSCEPTIBLE TO ADDITIONAL
SHWRS/ISOLATED TSTMS DUE TO ITS PROXIMITY TO THE WEAKENING
CYCLONIC FLOW...THUS HAVE KEPT POPS IN THE FCST THRU THE DAY.
CNTRL WI SHOULD SEE IMPROVING CONDITIONS...ESPECIALLY DURING THE
AFTERNOON AS DRIER AIR BEGINS TO ADVECT INTO THE AREA. NORTH WINDS
WL USHER IN COOLER AIR INTO THE FCST AREA WITH MAX TEMPS ONLY IN
THE UPR 60S TO LWR 70S NORTH/LAKESIDE...MID TO UPR 70S SOUTH.

WHILE A STRAY SHWR MAY LINGER INTO EARLY TUE EVENING IN THE
EAST...EXPECT DRY CONDITIONS OVER NE WI TO PREVAIL AS THE HI PRES
MOVES INTO THE WRN GREAT LAKES. SKY CONDITIONS TO RANGE FROM
MOSTLY CLEAR TO PARTLY CLOUDY OVRNGT AND WHEN COMBINED WITH WEAK
CAA AND RELATIVELY LIGHT NE WINDS...A COOL NGT ON TAP TO START OFF
THE MONTH OF JULY. MIN TEMPS TO DIP INTO THE MID TO UPR 40S
NORTH...LWR TO MID 50S SOUTH.

NW FLOW ALOFT REMAINS IN PLACE AT MID-WEEK WITH A SERIES OF MID-
LEVEL SHORTWAVES DIVING SEWD FROM THE NRN PLAINS TO THE TN VALLEY.
EACH SHORTWAVE WL INTERACT WITH DAYTIME HEATING BOTH WED AND THU
AND ATTEMPT TO PUSH SHWRS/ISOLATED TSTMS TOWARD CNTRL WI. MUCH OF
THIS POTENTIAL PCPN WL NOT REACH THE FCST AREA DUE TO THE WEAK SFC
HI STILL RESIDING OVER THE GREAT LAKES. PREFER TO KEEP THIS TIME
FRAME DRY FOR NOW AND KEEP ANY PCPN TO OUR WEST AND SOUTH. TEMPS
TO CONT RUNNING BELOW NORMAL WITH READINGS ABOUT 5 TO 10 DEGS
BELOW EARLY JULY STANDARDS.

ITS APPEARS THAT THIS HI PRES MAY HOLD ON LONG ENUF (THRU THU NGT)
BEFORE FINALLY RELENTING TO A WEAK SHORTWAVE TROF AND CDFNT ON
FRI. AS ONE WOULD EXPECT...MODEL TIMING VARIES WITH THE LOCATION
OF THIS WEAK DISTURBANCE...SO HAVE BROAD-BRUSHED SMALL CHC POPS
THROUGHOUT THE ENTIRE FCST AREA. WINDS AHEAD OF THIS LITTLE SYSTEM
ARE FCST TO TURN SW...THUS BRINGING A LITTLE WARMER AIR TO NE WI.
LOOK FOR MAX TEMPS TO REACH THE LWR 70S NORTH/NEAR LAKE MI...MID
TO UPR 70S SOUTH.

THE SHORTWAVE TROF AND CDFNT TO DEPART THE AREA FRI NGT...LEAVING
WEAK HI PRES OVER THE GREAT LAKES FOR THE 4TH OF JULY. IF THIS
SCENARIO PLAYS OUT CORRECTLY...WL NEED TO CARRY OVER POP FRI NGT
WITH QUIET CONDITIONS FOR THE START OF NEXT WEEKEND.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1012 PM CDT SAT JUN 27 2015

VFR CONDITIONS ARE EXPECTED TO PREVAIL THROUGH THE TAF PERIOD...
WITH THE POSSIBLE EXCEPTION OF PATCHY REDUCED VSBYS IN FOG
LATE TONIGHT...AND WITH SHOWERS/ISOLD TSTMS OVER CENTRAL WI
SUNDAY AFTERNOON/EARLY EVG.

ONLY SCT ALTOCUMULUS EXPECTED OVERNIGHT. NOT ANTICIPATING ANY
SIGNIFICANT PROBLEM WITH FOG...AS AFTERNOON DEW POINTS MIXED OUT
AND DROPPED INTO THE 40S ACROSS MOST OF THE FORECAST AREA.
ALTHOUGH PATCHY MVFR/IFR VSBYS IN FOG ARE POSSIBLE...CONFIDENCE
IS NOT HIGH ENOUGH TO PUT FOG IN ANY OF THE TAFS AT THIS TIME.
MODEL VSBY FORECASTS AND MOS GUIDANCE SUPPORT THIS THINKING.

AN UPPER LEVEL DISTURBANCE IS EXPECTED TO PIVOT AROUND THE AREA
ON SUNDAY AND SUNDAY EVENING...AFFECTING MAINLY CENTRAL WI. WILL
KEEP A TEMPO GROUP FOR SHOWERS AT AUW/CWA DURING THE LATE
AFTERNOON AND EARLY EVG...AND A PROB30 AT RHI...BUT PLAN TO
KEEP THE EASTERN TAF SITES DRY (THOUGH PCPN MAY GET VERY CLOSE TO
ATW).
&&

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

$$

SHORT TERM.....KURIMSKI
LONG TERM......KALLAS
AVIATION.......KIECKBUSCH


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