Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 121806
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
106 PM CDT SAT JUL 12 2014

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 359 AM CDT SAT JUL 12 2014

FORECAST CONCERN ON PCPN TRENDS TODAY INTO THIS EVENING. WEAK COLD
FRONT WORKING WAY INTO THE STATE ATTM. FEW FEATURES UPSTREAM TO
FOCUS ON...SHORT WAVE MOVING THROUGH CENTRAL PLAINS AND JET MOVING
ALONG U.S./CANADIAN BORDER. HAVE TRENDED TOWARDS NAM/RUC GIVEN HOW
VERIFYING THIS PAST EVENING. CURRENT RADAR TRENDS SHOWING
INCREASING ACTIVITY OVER NE AND IA AHEAD OF SHORT WAVE. LOOK FOR
INCREASING SHOWER AND THUNDERSTORM ACTIVITY THIS AFTERNOON AS
SFC WAVE SHIFTS NE OUT OF CENTRAL PLAINS. HAVE STAYED WITH LIKELY
POPS SOUTHERN HALF CWA. NAM BRINGS 70 DEW POINTS NORTH INTO THE
CWA LATER THIS MORNING. NOT UNREASONABLE WITH DEWS IN THE 70S
LURKING IN IA. MODELS SHOWING MID LEVEL INSTABILITY ON MARGINAL
SIDE...THOUGH SURFACE BASED CAPES EXPECTED TO BE AROUND 2K. FEW
STORMS THIS AFTERNOON COULD BE STRONG...THOUGH BEST CHANCE FOR
SEVERE APPEARS SOUTH OF AREA WHERE BETTER SHEAR RESIDES.

PCPN TO EXIT EAST LATE EVENING. MODELS ALL TRENDING DRY FOR SECOND
HALF OF SAT NIGHT INTO SUNDAY...AS SECONDARY COLD FRONT/SUBSIDENCE
WORK SOUTH THROUGH AREA.

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 359 AM CDT SAT JUL 12 2014

AN UPPER LEVEL LOW WILL DROP SOUTHEAST INTO THE GREAT LAKES LATE
SUNDAY NIGHT INTO MONDAY. THIS SYSTEM WILL BRING UNSEASONABLY COOL
TEMPERATURES TO THE REGION MONDAY ALONG WITH SHOWERS LIKELY. 500MB
TEMPERATURES EXPECTED TO DROP TO AROUND -24C AND 850MB TEMPERATURES
DOWN TO +4C. MODIFIED SOUNDINGS AT GREEN BAY INDICATED WINDEX
VALUES AROUND 30 KNOTS AND WET BULB HEIGHTS OF FIVE TO SIX
THOUSAND FEET. NOT SURE IF I HAVE SEEN WET BULB HEIGHTS THIS LOW IN
JULY IN A LONG TIME...IF AT ALL. WOULD NOT BE SURPRISED IF SOME OF
THE STRONGER SHOWERS PRODUCE SOME SMALL HAIL. CONSIDERED ADDING
THUNDER BASED ON 45 DEW POINT AND 25 BELOW TEMPERATURE AT 500 MB
RULE. IF WAS CLOSE...BUT PLENTY OF TIME TO ADD THUNDER IF THUNDER
PARAMETERS LOOK BETTER. DID LOWER MAX TEMPERATURES A FEW MORE
DEGREES ON MONDAY...ESPECIALLY ACROSS THE NORTH DUE TO THICKER
CLOUD COVER AND EARLIER ARRIVAL OF THE SHOWERS.

INTERESTING TIDBIT FOR MONDAY NIGHT WILL BE THE WINDS ACROSS
DOOR COUNTY. CENTRAL BAY OF GREEN BAY TEMPERATURES WERE AROUND
18C...GIVING BAY TO 850MB TEMPERATURE DIFFERENCES AROUND 15C.
DEEPER MIXING OVER THE BAY COULD PRODUCE GUSTY WINDS OF 15
TO 25 MPH...ESPECIALLY OVER THE NORTHERN PORTION OF THE COUNTY.
VERY UNUSUAL TO WORRY ABOUT DEEP MIXING OVER THE BAY THIS TIME
OF YEAR...MORE TYPICAL OF THE FALL MONTHS.

CYCLONIC FLOW AND HEATING OF THE DAY SHOULD LEAD TO MORE SHOWER
ACTIVITY ON TUESDAY...BUT NOT AS NUMEROUS AS MONDAY. LINGERED
SHOWERS INTO THE EVENING HOURS.

ALTHOUGH THE FORECAST IS DRY ON WEDNESDAY AND THURSDAY...NOT
COMPLETELY SOLD ON THE DRY FORECAST AS MODELS SHOW WEAK RIPPLES
AT 500MB. WOULD NOT BE SURPRISED IF THERE WERE SOME ISOLATED
SHOWERS ON THESE DAYS...BUT CONFIDENCE WAS NOT THERE IN ADDING
THEM TO THE FORECAST AT THIS TIME. A GRADUAL MODERATING TREND
IS EXPECTED LATER NEXT WEEK.

HIGH TEMPERATURES MONDAY AND TUESDAY COULD APPROACH OR EVEN
BREAK RECORD LOW MAXIMUM TEMPERATURES FOR THE DATE.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 106 PM CDT SAT JUL 12 2014

CIGS WERE MAINLY MVFR ACROSS NORTH CENTRAL AND
NORTHEAST WISCONSIN...IN THE VICINITY OF A COLD FRONT THAT WAS
SLOWLY PUSHING SOUTHEAST. CIGS ACROSS THE REST OF THE AREA WERE
VFR. LEFT OUT MENTION OF THUNDER IN THE RHI TAF AND ONLY HAVE
SHOWERS IN THE VICINITY...THOUGH THE ENTIRE AREA IS IN SPC DAY 1
GENERAL THUNDER. MUCAPE AT RHI WAS IN EXCESS OF 1000J/KG WITH NO
CIN AS OF 17Z...BUT THUNDER HAS BEEB CONFINED TO WESTERN
WISCONSIN AND MINNESOTA. THINK THE POTENTIAL FOR THUNDER SHOULD
DECREASE ONCE THE COLD FRONT PASSES.

HAVE LOWER CLOUDS MOVING INTO CENTRAL AND EAST CENTRAL WISCONSIN
TAF SITES DURING THE LATE AFTERNOON AND EARLY EVENING WITH
SHOWERS IN THE VICINITY...AND TEMPO THUNDER WITH MVFR CIGS AS AN
UPPER LEVEL SHORT WAVE PASSES ACROSS WISCONSIN. GRB AND ARX RADARS
HAD ECHOES OVER CENTRAL WISCONSIN AT 1745Z...AROUND 8-9KFT AGL
BUT SURFACE OBSERVATIONS IN THAT AREA HAD YET TO INDICATE ANY
RAIN.

EXPECT CLOUDS TO DECREASE OVERNIGHT AS THE SHORT WAVE DEPARTS AND
THE FRONT SLOWLY DIES OFF AS IT SLOWLY MOVES SOUTHEAST.
&&

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

$$

SHORT TERM.....TE
LONG TERM......ECKBERG
AVIATION.......MG






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