Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 291745
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1245 PM CDT TUE JUL 29 2014

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND WEDNESDAY
ISSUED AT 359 AM CDT TUE JUL 29 2014

PCPN TRENDS THROUGH THE PERIOD...AND THE POTENTIAL FOR A FEW
STRONG TSTMS WITH HAIL THIS AFTERNOON...WILL BE THE MAIN FCST
CONCERNS.

A S/W TROF WAS EXITING THE SOUTHERN PART OF THE FORECAST AREA
EARLY THIS MORNING...AND ANOTHER WAS APPROACHING FROM ONTARIO.
SHOWERS HAD ENDED ACROSS WI...THOUGH REGIONAL RADAR STILL SHOWED
A FEW SHOWERS OVER THE MN ARROWHEAD. SCT-BKN CLOUDS COVERED THE
REGION...AND PATCHY FOG HAD DEVELOPED OVER NC WI.

THE NEXT S/W TROF IS EXPECTED TO MOVE THROUGH THE FORECAST AREA
THIS AFTERNOON (ROUGHLY FROM 18Z-22Z ACCORDING TO EXTRAPOLATION)...
AND SHOULD TRIGGER SCT/NMRS SHRA/TSRA. WILL CARRY HIGH-END CHANCE
OR LIKELY POPS OVER THE ENTIRE CWA. MODIFIED FCST SOUNDINGS (USING
TEMPS IN THE MID TO UPPER 70S AND DEW POINTS IN THE LOWER TO
MIDDLE 50S) SUPPORT SBCAPE OF 1000-1500 J/KG AND LI`S -3 TO -5.
WET BULB ZERO HGTS AROUND 9K FT AND COLD AIR ALOFT (H5 TEMPS -16
TO -18) WILL BE VERY FAVORABLE FOR HAIL. SPC HAS MOST OF GRB CWA
IN A 5% RISK AREA FOR LARGE HAIL...AND THIS LOOKS REASONABLE...SO
WILL MENTION THE POTENTIAL FOR ISOLD SVR TSTMS THIS AFTERNOON AND
EARLY EVG IN THE HAZARDOUS WEATHER OUTLOOK.

ANOTHER S/W TROF WILL MOVE THROUGH THE REGION TONIGHT...ACCOMPANIED
BY A WEAK CANADIAN COLD FRONT. WILL HAVE CHC POPS DURING THE EVG...
AND CARRY SLIGHT CHANCES INTO THE OVERNIGHT HOURS BEFORE ENDING
LATE. WEAK RIDGING OVER NC/FAR NE WI MAY ALLOW PATCHY FOG TO
DEVELOP OVERNIGHT. LOWS TEMPS SHOULD DROP INTO THE MIDDLE TO UPPER
40S AT THE COOL SPOTS IN THE NORTHWOODS...AND LOWER TO MIDDLE
50S ELSEWHERE.

ON WEDNESDAY...ANOTHER IN A STRING OF S/W TROFS SHOULD PASS BY TO
OUR NORTHEAST DURING THE AFTERNOON...WITH THE LFQ OF A 70 KT JET
POSSIBLY IMPACTING FAR NE WI. THE AIR MASS IS NOT EXPECTED TO BE
AS UNSTABLE AS TODAY...SO AFTERNOON CONVECTION SHOULD BE ISOLD/SCT.
MIXING THROUGH 800-750 MB SUPPORTS HIGH TEMPS IN THE LOWER TO
MIDDLE 70S.

.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY
ISSUED AT 359 AM CDT TUE JUL 29 2014

CLOSED UPPER LOW OVER ONTARIO/QUEBEC CANADA WILL MEANDER ACROSS
THE EASTERN PORTION OF CANADA INTO THE WEEKEND. CLOSED LOW WILL
EJECT EASTWARD NEXT SUNDAY INTO MONDAY. PERSISTENT NORTHWEST FLOW
EXPECTED ACROSS THE WESTERN LAKES WITH PERIODIC CHANCES FOR
SHOWERS AND STORMS THROUGH MUCH OF THE PERIOD.

TIMING OF THESE FEATURES THIS FAR OUT DIFFICULT TO PINPOINT...BUT
BEST CHANCES FOR SHOWERS AND STORMS WILL BE DURING THE AFTERNOON
AND EARLY EVENING HOURS WEDNESDAY THROUGH SATURDAY. A LOT OF
UNCERTAINTY ON HOW THE SUNDAY AND MONDAY WILL PLAY OUT...THUS DID
NOT INCLUDE IN THE HAZARDOUS WEATHER OUTLOOK. DID ADJUST MIN
TEMPERATURES DOWN A DEGREE OR TWO ON A FEW NIGHTS. ONLY REAL
CHANGE WAS TO ADD A FEW DEGREES TO OUR TYPICAL WARM SPOTS/SANDY
SOIL REGIONS. LATER SHIFTS MAY NEED TO ADJUST LAKESHORE REGION
DOWN AS WATER TEMPERATURE AT STURGEON BAY THIS EVENING WAS ONLY
50 DEGREES.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1245 PM CDT TUE JUL 29 2014

SHORT WAVE ENERGY IN CYCLONIC UPPER LEVEL FLOW AND AN
APPROACHING SURFACE BOUNDARY WILL BING SHOWERS AND A CHANCE FOR
THUNDERSTORMS TO THE AREA THIS AFTERNOON INTO THE EVENING. LOCAL
MESOANALYSIS INDICATED LITTLE OR NO CIN AT MIDDAY WITH
500-1000J/KG OF CAPE IN MOST LOCATIONS SO DEVELOPMENT CAN BE
EXPECTED AT ANY TIME. THE FREEZING LEVEL AND WET BULB ZERO HEIGHT
FROM THE 12Z GRB SOUNDING WERE BOTH BELOW 10KFT...SO HAIL IS
POSSIBLE WITH THUNDERSTORMS. GENERALLY VFR CONDITIONS EXCEPT IN
SHOWERS AND STORMS TODAY...WHERE THERE MAY BE SOME MVFR CIGS AND MVFR
OR IFR VSBYS. WEAK SURFACE FLOW AND CLEARING SKIES TONIGHT MAY
BRING AREAS OF MVFR VSBYS...AND ISOLATED IFR VSBYS...IN FOG.
&&

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

$$

SHORT TERM.....KIECKBUSCH
LONG TERM......ECKBERG
AVIATION.......MG






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