Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 232317
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
617 PM CDT THU JUL 23 2015

UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND FRIDAY
ISSUED AT 219 PM CDT THU JUL 23 2015

CU CONGESTUS WILL DISSIPATE AROUND SUNSET AND SKIES MAINLY CLEAR
OVERNIGHT. TEMPS A BIT WARMER THAN LAST NIGHT GIVEN INCREASING
MOISTURE AND WEAK WARM AIR ADVECTION.

FIRST OF A PAIR OF SHORTWAVE TROFS APPROACH THE STATE BY 24/12Z.
WEAK WARM AIR ADVECTION ENHANCES LIFT AND TSTORM CHANCES ACROSS
MAINLY WESTERN PART OF FCST AREA DURING THE DAY. HIGHS WILL BE
SIMILAR TO TODAY...EXCEPT A COUPLE DEGS COOLER IN AREAS WITH
EXTENSIVE CLOUDS.

.LONG TERM...FRIDAY AFTERNOON THROUGH THURSDAY
ISSUED AT 219 PM CDT THU JUL 23 2015

FAIRLY ZONAL FLOW EXPECTED INTO EARLY NEXT WEEK...THEN PATTERN
WILL SHIFT TO A NORTHWEST FLOW AS 500MB RIDGE BUILDS ACROSS THE
SOUTHWESTERN UNITED STATES.

MAIN CONCERN FOR THIS PACKAGE WILL BE THE SEVERE THUNDERSTORM
POTENTIAL FRIDAY AFTERNOON AND FRIDAY NIGHT AS A WEAK COLD FRONT
MOVES ACROSS THE REGION. MANY ISSUES TO CONTEND WITH WILL BE
MORNING CONVECTION WEST OF THE AREA THAT IS EXPECTED TO DIVE
SOUTHEAST...WHEN WILL THE CAP WILL BREAK FRIDAY AFTERNOON AND HOW
FAR EAST STRONG OR SEVERE CONVECTION WILL MAKE IT INTO EASTERN
WISCONSIN LATER FRIDAY NIGHT.

MODIFIED SOUNDINGS AT WAUSAU INDICATED SURFACE/MOST UNSTABLE
CAPES OF 1500 TO 2500 J/KG...0-6KM SHEAR VALUES AROUND 40 KNOTS...
AND WET BULB HEIGHTS AROUND ELEVEN THOUSAND FEET TO SUPPORT STRONG
OR SEVERE THUNDERSTORMS ACROSS CENTRAL/NORTH-CENTRAL WISCONSIN
INTO FRIDAY EVENING. A LOT OF DRY AIR ALOFT WHICH MAY HELP TO
LIMIT COVERAGE OF THE CONVECTION. THE DRY AIR WILL ALSO PLAY A
ROLE ON HOW QUICKLY THE STORMS WEAKEN AFTER SUNSET. ON THE
FLIP SIDE...0-6KM SHEAR VALUES MAY SUPPORT STORMS TO LINGER MORE
INTO THE EVENING AND OVERNIGHT HOURS. THE MARGINAL/SLIGHT RISK
OF STORMS WEST OF A MARINETTE TO OSHKOSH LINE SEEMS REASONABLE.
FOR LOCATIONS TO THE EAST...WILL NEED TO MONITOR LATER MODEL
RUNS TO SEE IF THE MARGINAL/SLIGHT RISK MAY NEED TO BE SHIFTED
A LITTLE FURTHER EAST.

SATURDAY SHOULD BE DRY AS HIGH PRESSURE BUILDS INTO THE REGION.
THE RING OF FIRE WILL BE IN PLAY EARLY NEXT WEEK AS WEAK
DISTURBANCES PASS ON THE NORTH SIDE OF THE 500MB RIDGE. TRYING
TO PINPOINT TIMING OF EACH SYSTEM WILL BE DIFFICULT AS THE MODEL
CONTINUE TO SHOW DIFFERING SOLUTIONS AT TIMES EARLY NEXT WEEK.
TEMPERATURES SHOULD REMAIN ABOVE NORMAL THROUGH THE MIDDLE OF
NEXT WEEK.
&&

.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 617 PM CDT THU JUL 23 2015

VFR WEATHER EXPECTED THROUGH MOST OF THE TAF PERIOD.
CLEARING SKIES TONIGHT WITH GROUND FOG POSSIBLE BETWEEN 09Z AND 12Z
FRIDAY. A WEAK COLD FRONT MOVING ACROSS THE AREA FRIDAY AFTERNOON
AND EVENING WILL BRING SHOWERS AND THUNDERSTORMS.  A FEW STORMS MAY
PRODUCE STRONG GUSTY WINDS AND NEAR SEVERE HAIL.
&&

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

$$

SHORT TERM.....JKL
LONG TERM......ECKBERG
AVIATION.......MPC



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