Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 241748
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1248 PM CDT THU JUL 24 2014

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND FRIDAY
ISSUED AT 314 AM CDT THU JUL 24 2014

WEAK CONVERGENCE COMBINED WITH SOME SUBTLE POOLING OF MOISTURE
CREATING SOME PATCHY CLOUDS OVER THE REGION THIS MORNING.
ANTICIPATE THESE CLOUDS TO DIMINISH AS LIGHT EAST TO SOUTHEAST
WINDS ADVECT DRIER AIR INTO THE AREA TODAY AND WILL PERSIST
TONIGHT. EXPECT SIMILAR FORECAST HIGH TEMPS TODAY COMPARED TO
WEDNESDAY.

FORECAST ISSUE TURNS TO LATE TONIGHT INTO FRIDAY WITH RETURN WAA
FLOW FROM THE WEST AND ON THE BACK SIDE OF THE SURFACE HIGH. UPPER
RIDGE OVER THE NORTHERN PLAINS TODAY WILL TURN MORE ZONAL AS A
STRONG UPPER SYSTEM DROPS INTO THE SOUTHWEST CANADA THROUGH
FRIDAY. STRONG WAA WITH INCREASING LLJ WILL LIKELY DEVELOP
CONVECTION OVER EASTERN SD...SOUTHERN MINNESOTA AND NORTHERN IOWA
LATE TONIGHT. CONSENSUS OF MODELS IS THE LEADING EDGE OF THIS
CONVECTION OR AT LEAST REMNANTS OF THIS CONVECTION REACHES PARTS
OF CENTRAL WISCONSIN LATE TONIGHT. DRIER FROM THE DEPARTING HIGH
PRESSURE REGION WILL LIKELY PROTECT MUCH OF THE REST OF THE
REGION.

MODELS FOR LATE TONIGHT INTO AT LEAST FRIDAY MORNING THEN FOCUS
THE BRUNT OF THE CONVECTION ALONG AND NORTH OF THE SURFACE
BOUNDARY LOCATED FROM IOWA INTO NORTHERN ILLINOIS. ANTICIPATE
HIGHER POPS WOULD BE LOCATED TO THE SOUTHWEST AND SOUTH OF THE
FORECAST AREA. OTHERWISE WILL TREND WITH SLIGHTLY HIGHER POPS OVER
THE WEST HALF OF THE STATE ON FRIDAY CLOSER TO THE GRADUALLY
ADVANCING SURFACE BOUNDARY. WILL CONTINUE THE SMALLER POPS OVER THE
EAST FRIDAY WITH THE CONTINUED WAA...BUT MODEL SOLUTIONS NOT IN
AGREEMENT IF PCPN WILL REACH THESE AREAS.

AS FAR AS THUNDERSTORM POTENTIAL...BEST INSTABILITY LOCATED TO THE
SOUTHWEST LATE TONIGHT INTO FRIDAY. DEEP LAYER SHEAR MAY BE ON THE
INCREASE AS RETURN SOUTHWEST FLOW IN THE LOWER LEVELS WILL BE
INTERACTING WITH THE NORTHWEST FLOW ALOFT AT THE ONSET BEFORE STRONGER
WESTERLY FLOW DEVELOPS LATER FRIDAY AS THE UPPER FLOW TURNS MORE
ZONAL.

EVEN THOUGH H850 TEMPERATURES WILL BE ON THE INCREASE
FRIDAY...ANTICIPATE MORE CLOUDS.

.LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 314 AM CDT THU JUL 24 2014

ZONAL FLOW EXPECTED AT THE BEGINNING OF THE PERIOD. 500MB TROUGH
WILL SWING ACROSS THE REGION SATURDAY NIGHT AND SUNDAY. PERSISTENT
NORTHWEST FLOW WILL CONTINUE FOR THE REMAINDER OF THE PERIOD AS
UPPER LOW MEANDERS ACROSS ONTARIO/QUEBEC. TEMPERATURES WILL START
OUT NEAR OR SLIGHTLY ABOVE NORMAL SATURDAY...THEN SHOULD TO OR
BELOW NORMAL SUNDAY THROUGH THE REMAINDER OF THE PERIOD.

STILL A LOT OF UNCERTAINTY ON SYSTEM FOR FRIDAY NIGHT AND SATURDAY...
THUS LOWERED CHANCES FOR SHOWERS AND STORMS. THE BEST CHANCE FOR
SHOWERS AND STORMS WILL BE ON SUNDAY AS UPPER TROUGH MOVES ACROSS
THE REGION. SOME LINGERING SHOWERS WILL CONTINUE INTO SUNDAY
EVENING. HIGH PRESSURE SHOULD BUILD INTO THE REGION FOR MONDAY.
NOT COMPLETELY CONVINCED MONDAY WILL BE DRY. CYCLONIC FLOW ALOFT
AND WEAK DISTURBANCE ROTATING AROUND THE UPPER LOW WILL BRING A
CHANCE OF SHOWERS AND STORMS TUESDAY AND WEDNESDAY. BEST CHANCES
WOULD BE DURING THE HEATING OF THE DAY.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1248 PM CDT THU JUL 24 2014

EXPECT VFR CONDITIONS THIS AFTERNOON AND
TONIGHT...WITH CIGS 040-060 FOR MUCH OF THE AFTERNOON. THERE IS A
CHANCE FOR SHOWERS...WITH MVFR VSBYS POSSIBLE...IN CENTRAL
WISCONSIN FRIDAY MORNING. CONFIDENCE IN TIMING OF SHOWERS COULD
BE BETTER BUT MODELS HAD SOME TIMING DIFFERENCES.
&&

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

$$

SHORT TERM.....TDH
LONG TERM......ECKBERG
AVIATION.......MG





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