Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 012007
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
307 PM CDT FRI AUG 1 2014

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND SATURDAY
ISSUED AT 306 PM CDT FRI AUG 1 2014

BORDERLINE SVR STORMS LATE THIS AFTERNOON/EARLY THIS EVENING...
EXTENT OF FOG TONIGHT AND THEN POTENTIAL FOR ADDITIONAL SHWRS/
TSTMS ON SAT WL BE THE MAIN FCST CONCERNS OVER THE NEXT 24 HOURS.

THE 19Z MSAS SFC ANALYSIS SHOWED A RELATIVELY DIFFUSE PATTERN FROM
THE PLAINS TO THE GREAT LAKES. WEAK HI PRES WAS SITUATED OVER THE
NRN GREAT LAKES...A COUPLE AREAS OF VERY WEAK LOW PRES WERE
SITUATED OVER WI...AND OTHER WEAK HI PRES SYSTEMS WERE LOCATED
OVER ND AND IA. A CLOSER LOOK INTO WI ALSO INDICATED A WEAK SFC
BOUNDARY DRAPED ACROSS CNTRL WI SEPARATING DRIER AIR TO THE NORTH
FROM MORE MOIST AIR TO THE SOUTH. IT IS ALONG THIS BOUNDARY WHERE
TSTMS CONT TO DEVELOP WITH THE HELP OF CAPES PUSHING 2K J/KG AND
STEEP MID-LEVEL LAPSE RATES.

CURRENT SHWR/TSTM ACTIVITY OVER CNTRL/E-CNTRL WI WL GRADUALLY
DIMINISH THIS EVENING AS DAYTIME HEATING WANES. UNTIL THEN...SOME
OF THE STORMS MAY BE STRONG ENUF TO PRODUCE PENNY-SIZE HAIL AND
LOCALLY HEAVY DOWNPOURS. ONCE THE PCPN ENDS...WEAK HI PRES OVER
THE GREAT LAKES WL ALLOW FOR SKIES TO BECOME MOSTLY CLEAR WITH
LIGHT WINDS. THIS SETS THE STAGE FOR FOG FORMATION...ESPECIALLY
WHERE HEAVIER PCPN FELL. NO HEADLINES FOR FOG...BUT ANTICIPATE
LOCALLY DENSE FOG WL BE POSSIBLE LATE TNGT. MIN TEMPS SHOULD BE
COMPARABLE TO LAST NGT WITH MID TO UPR 40S NORTH...MID TO UPR 50S
CNTRL/E-CNTRL WI.

UPR HEIGHTS BEGIN TO BUILD ACROSS WI ON SAT IN RESPONSE TO THE
STUBBORN HUDSON BAY UPR LOW PULLING FARTHER NE. THE AIR MASS OVER
WI WL NOT BE AS COOL ALOFT COMPARED TO THE PREVIOUS FEW DAYS...
HOWEVER MDLS STILL SHOW CAPE VALUES PUSHING 1K J/KG OVER CNTRL WI
BY SAT AFTERNOON. MID-LEVEL LAPSE RATES ARE ALSO NOT AS STEEP AND
THERE IS NOT ANY MID-LEVEL SHORTWAVES DROPPING THRU THE REGION.
THEREFORE...PCPN COVERAGE ON SAT TO BE LESS THAN TODAY AND FOCUSED
PRIMARILY OVER CNTRL WI. MAX TEMPS TO AGAIN BE A FEW DEGS EITHER
SIDE OF 80 DEGS...EXCEPT NEAR LAKE MI WHERE MID 70S ARE EXPECTED.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
ISSUED AT 306 PM CDT FRI AUG 1 2014

WEAK UPPER RIDGING SHOULD KEEP THE REGION MAINLY DRY
SATURDAY NIGHT...THEN AN UPPER TROUGH AND ASSOCIATED SURFACE FRONT
WILL BRING A GOOD CHANCE OF THUNDERSTORMS SUNDAY THROUGH MONDAY AS IT
MOVES SLOWLY SOUTHEAST ACROSS THE AREA.

THE NEWEST MODEL RUNS NOW PUSH THE SURFACE FRONT FAR ENOUGH SOUTH
OF THE FORECAST AREA TO PRODUCE MOSTLY DRY WEATHER MONDAY NIGHT
THROUGH FRIDAY EXCEPT PERHAPS DURING THE MIDDLE OF THE WEAK WHEN A
SYSTEM COMES BY IN THE NORTHWEST UPPER FLOW.

THE TREND THIS SUMMER HAS BEEN TO KEEP A BIG HUDSON BAY TO GREAT
LAKES SURFACE HIGH ACROSS THE REGION WHICH MAKES SENSE GIVEN THE
COOLER THAN NORMAL LAKE TEMPERATURES. SO IT MAY TURN OUT TO BE A
GENERALLY DRY AND COMFORTABLE PERIOD FOR MUCH OF THE NEXT WORK
WORK PROVIDING THE MODELS CONTINUE TO KEEP THE FRONT TO OUR SOUTH.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1231 PM CDT FRI AUG 1 2014

WHILE VFR CONDITIONS WL BE THE PREDOMINANT CATEGORY OVER THE NEXT
24 HOURS...WE WL HAVE TO DEAL WITH SCT SHWRS/TSTMS THIS AFTERNOON/
EVENING AND THEN PATCHY/AREAS OF FOG LATE TNGT. MUCH AS HAS BEEN
THE CASE OVER THE PAST FEW DAYS...DAYTIME HEATING HAD COMBINED
WITH STEEP MID-LEVEL LAPSE RATES...CAPES BETWEEN 1K AND 2K J/JG
AND A SUBTLE SFC BOUNDARY TO GENERATE TSTM ACTIVITY ACROSS NE WI.
SHEAR IS VERY WEAK...THUS DO NOT ANTICIPATE STORMS TO ROTATE.
INSTEAD...WITH THE RELATIVELY LOW WET-BULB ZERO HEIGHTS AND LIGHT
WINDS ALOFT...EXPECT SMALL HAIL AND LOCALLY HEAVY DOWNPOURS TO
ACCOMPANY ANY TSTMS. THE PRECIPITATION WL DISSIPATE MID TO LATE
EVENING AS DAYTIME HEATING WANES...LEAVING DECREASING CLOUDS AND
LIGHT WINDS. LOOK FOR FOG TO REDEVELOP ONCE AGAIN DURING THE
OVERNIGHT HOURS. THERE MAY BE PERIODS OF MVFR CIGS/VSBYS
ASSOCIATED WITH BOTH THE PRECIPITATION AND THE FOG.
&&

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

$$

SHORT TERM.....KALLAS
LONG TERM......RDM
AVIATION.......KALLAS






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