Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 270804
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
304 AM CDT SAT JUN 27 2015

FORECAST DISCUSSION FOR ROUTINE MORNING FORECAST ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 304 AM CDT SAT JUN 27 2015

AFTER SOME PATCHY MORNING FOG OUT TO THE WEST...A RIDGE OF HIGH
PRESSURE WILL KEEP CONDITIONS QUIET TODAY WITH MOSTLY SUNNY SKIES
ACROSS THE AREA. ABUNDANT SUNSHINE AND MODEST WARM AIR ADVECTION
AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM WILL BRING AFTERNOON
HIGHS TO AROUND 80 DEGREES AWAY FROM LAKE MICHIGAN.

THE HIGH WILL KEEP THE AFOREMENTIONED APPROACHING LOW AT BAY A BIT
LONGER THAN PREVIOUSLY FORECAST AS RECENT MODEL RUNS HOLD OFF MUCH
OF THE RAIN UNTIL DURING THE DAY ON SUNDAY. GIVEN THE MODEL TRENDS
ARE IN FAIRLY GOOD AGREEMENT WILL LOWER POPS LATE TONIGHT ACROSS
THE WESTERN CWA TONIGHT AS INCREASING CLOUDS KEEP OVERNIGHT LOWS A
BIT WARMER IN THE LOWER TO MIDDLE 50S.

THE MAIN CONCERN ON SUNDAY WILL BE TIMING OF SHOWERS AND
THUNDERSTORMS AS A LOW PRESSURE SYSTEM APPROACHES FROM THE WEST.
AS WAS PREVIOUSLY MENTIONED THE TIMING OF THE LOW HAS SLOWED DOWN
FROM PREVIOUS RUNS. IN FACT THERE ARE PORTIONS OF THE EASTERN CWA
THAT COULD BE COMPLETELY DRY THROUGH THE DAY ON SUNDAY. WITH THE
MODEL TRENDS IN MIND WILL TIME THE PRECIPITATION LATER THAN THE
PREVIOUS FORECAST. MODEL SOUNDINGS SHOW A HEALTHY AMOUNT OF SBCAPE
ON SUNDAY...WITH VALUES OF 1000 TO 1500 J/KG. THE INCREASED
INSTABILITY SHOULD LEAD TO MORE THUNDERSTORM ACTIVITY THAN
PREVIOUSLY FORECAST. DESPITE THE INSTABILITY SHEAR PROFILES ARE
EXTREMELY WEAK WITH 0-6 KM SHEAR PROFILES OF 15 KNOTS. WITH THE
LONG SKINNY CAPE PROFILES HEAVY RAIN WILL BE THE MAIN THREAT WITH
THE SEVERE THREAT BEING VERY MINIMAL.

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 304 AM CDT SAT JUN 27 2015

HIGHLY-AMPLIFIED FLOW CONSISTING OF A ROCKIES UPR RDG AND ERN
CONUS UPR TROF TO PRETTY MUCH REMAIN INTACT THRU THE END OF NEXT
WEEK...ALTHO THE UPR RDG DOES GRADUALLY RETROGRADE TOWARD THE WEST
COAST AND WEAKEN A BIT. THIS PATTERN WL CONT TO SEND VARIOUS
PIECES OF MID-LEVEL ENERGY SEWD THRU THE GREAT LAKES AND BRING
PERIODIC BOUTS OF SHWRS/ISOLATED TSTMS. TRYING TO TIME THE PASSAGE
OF EACH PIECE OF ENERGY TO BE THE MAIN FCST CHALLENGE. TEMPS
SHOULD END UP AT OR SLIGHTLY BELOW NORMAL THRU THE PERIOD.

AS THE INITIAL SYSTEM CONTS TO TRACK SE INTO IL SUNDAY NGT...
PCPN TRENDS WL GRADUALLY DIMINISH FROM NORTH TO SOUTH ACROSS THE
FCST AREA. WL CONT TO RUN THE HIGHER POPS OVER CNTRL/E-CNTRL WI
DURING THE EVENING HOURS WITH NOT MUCH EXPECTED AFTER MIDNGT AS
BETTER FORCING SHIFTS SOUTH. LOW-LEVEL MOISTURE DOES NOT GET
SCOURED OUT BEHIND THIS SYSTEM...THUS EXPECT A GOOD DEAL OF CLOUDS
TO HANG AROUND THRU THE NGT WITH PATCHY FOG DEVELOPING. MIN TEMPS
TO RANGE FROM THE LWR TO MID 50S NORTH...GENERALLY IN THE 55-60
DEG RANGE SOUTH.

IT STILL APPEARS THAT SHWRS/ISOLATED TSTMS WL POP UP OVER THE
REGION ON MON AS DAYTIME HEATING INTERACTS WITH A CYCLONIC FLOW/
COOL POOL ALOFT. THERE MAY BE ENUF INSTABILITY PRESENT TO ALLOW A
FEW STORMS TO PRODUCE SMALL HAIL (CAPES AROUND 1500 J/KG).
OTHERWISE...BRIEF HEAVY RAIN WOULD BE THE PRIMARY THREAT WITH DEW
POINTS AROUND 60 DEGS AND PW VALUES SURPASSING 1.25". MAX TEMPS TO
RANGE FROM THE LWR 70S NEAR LAKE MI...MID TO UPR 70S CNTRL/E-CNTRL
WI.

PCPN CHCS WL CARRY OVER INTO MON EVENING UNTIL SUNSET...THEN THE
LOSS OF DAYTIME HEATING SHOULD ALLOW ANY SHWRS TO GRADUALLY
DIMINISH OVRNGT. IT IS DEBATABLE WHETHER THERE WL BE ENUF
SUBSIDENCE OR SLIGHTLY DRIER AIR MOVING INTO WI TO ALLOW FOR MUCH
CLEARING...BUT HAVE GONE OPTIMISTIC AND OPTED FOR PARTLY CLDY
SKIES AFTER MIDNGT. MIN TEMPS WL DROP INTO THE LWR TO MID 50S
NORTH...MID TO UPR 50S SOUTH. LITTLE CHANGE IS ANTICIPATED
SYNOPTICALLY HEADED INTO TUE WITH THE PREVAILING NW FLOW IN PLACE
AND WEAK SHORTWAVES DIVING SE THRU THE REGION. THERE DOES APPEAR
TO BE SOME SLIGHT WARMING ALOFT...THUS INSTABILITY IS NOT AS GREAT
AS PREVIOUS DAYS. NONETHELESS...CANNOT RULE OUT AT LEAST A SMALL
THREAT FOR MORE POP-UP SHWRS/ISOLATED STORMS ON TUE. MAX TEMPS
LOOK TO BE CLOSE TO MON`S READINGS...WHICH IS JUST A TOUCH BELOW
NORMAL.

MODELS SEEM TO BE IN AGREEMENT IN SAGGING A WEAK AREA OF HI PRES
SWD INTO THE WRN GREAT LAKES ON WED. THIS WOULD BRING ENUF DRY AIR
INTO NRN SECTIONS OF WI TO ACTUALLY BRING A DRY FCST TO THE ENTIRE
FCST AREA. A N-NE WIND WL KEEP TEMPS IN CHECK DESPITE A GOOD
AMOUNT OF SUNSHINEL. MAX TEMPS TO RANGE FROM NEAR 70 DEGS NEAR
LAKE MI...TO THE MID 70S OVER PARTS OF CNTRL WI.

THIS HI PRES IS FCST TO KEEP OUR WEATHER QUIET WED NGT THRU MOST
OF THU...BUT THERE IS MODEL TIMING ISSUES WITH REGARDS TO THE NEXT
SYSTEM PUSHING ACROSS THE NRN PLAINS. HAVE FOLLOWED MODEL
CONSENSUS HERE WHICH BRINGS A SMALL CHC POP INTO CNTRL WI ON THU.
THAT BEING SAID...MODELS TYPICALLY SLOW ADVANCING SYSTEMS DOWN
WITH TIME...THUS WOULD NOT BE THE LEAST BIT SURPRISED TO SEE THU
REMAIN DRY THRU THE DAYLIGHT HOURS. MAX TEMPS ARE EXPECTED TO BE A
COUPLE OF DEGS WARMER THAN WED (STILL BELOW NORMAL FOR EARLY
JULY).

THIS UNCERTAINTY THEN CARRIES OVER FOR THU NGT/FRI AS SOME MODELS
FAVOR PUSHING THIS SYSTEM THRU THE WRN GREAT LAKES...WHILE OTHERS
STILL HAVE THIS SYSTEM JUST REACHING THE FCST AREA BY 00Z SAT.
JUST TOO MUCH QUESTIONS HERE TO DETERMINE WHICH SOLUTION IS
CORRECT...THUS WL GO WITH A SMALL POP FOR NOW AND HOPE THE MODELS
RESOLVE THIS TIMING ISSUE IN LATER FCSTS. TEMPS WL CONT TO RUN
SLIGHTLY BELOW NORMAL THRU FRI.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1024 PM CDT FRI JUN 26 2015

MOSTLY CLEAR CONDITIONS ARE ANTICIPATED OVERNIGHT. AS WAS THE
CASE LAST NIGHT...SOME FOG IS EXPECTED TO FORM OVER NORTH CENTRAL
AND FAR NORTHEAST WI. HAVE KEPT A TEMPO GROUP FOR VLIFR
CONDITIONS AT THE RHI TAF SITE OVERNIGHT...AS THEY WILL BE
SITUATED BENEATH A WEAK SFC RIDGE AND HAVE VERY LIGHT OR CALM
WINDS. PATCHY FOG MAY ALSO DEVELOP NEAR AUW/CWA. FOG SHOULD MIX
OUT EARLY SATURDAY MORNING...FOLLOWED BY PARTLY CLOUDY SKIES
AND VFR CONDITIONS THROUGH THE AFTERNOON/EVENING.
&&

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

$$

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


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