Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 051755
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1255 PM CDT TUE MAY 5 2015

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND WEDNESDAY
ISSUED AT 327 AM CDT TUE MAY 5 2015

VERY LOW RELATIVE HUMIDITY AND ELEVATED FIRE WEATHER CONDITIONS OVER
FAR NORTHERN WI TODAY...AND PCPN AND TEMPERATURE TRENDS THROUGH THE
ENTIRE PERIOD...ARE THE MAIN FCST CONCERNS.

SHOWERS AND ISOLD TSTMS WERE LIFTING NORTH TOWARD THE FCST AREA EARLY
THIS MORNING. THIS PCPN WAS ASSOCIATED WITH A H8 WARM FRONT...A SHORT-
WAVE TROF AND THE RRQ OF A JET STREAK. WITH HIGH PRESSURE RIDGED ACROSS
NORTHERN WI AND DRY NE FLOW INTO THE FORECAST AREA...DO NOT EXPECT
THIS PCPN TO MAKE MUCH...IF ANY...HEADWAY INTO OUR SOUTHERN COUNTIES
THIS MORNING. SOME THICKER CLOUD COVER WILL IMPACT C/EC WI THOUGH.
EXPECT PLENTY OF SUNSHINE OVER THE FAR NORTH...WHERE DEEP MIXING WILL
CAUSE DEW POINTS TO FALL INTO THE LOWER TO MIDDLE 20S. RELATIVE HUMIDITY
IS EXPECTED TO DROP INTO THE TEENS OVER THE FAR NORTH...WHICH WILL LEAD
TO SOME FIRE WEATHER CONCERNS.

THE H8 WARM FRONT IS EXPECT TO LIFT NORTH THROUGH THE FORECAST AREA
TONIGHT INTO WEDNESDAY MORNING...AND BRING SCT SHOWERS AND ISOLD TSTMS
TO THE REGION. THE ECMWF CONTINUES TO BE MORE AGGRESSIVE WITH QPF
AMOUNTS TONIGHT...BUT CONFIDENCE IS NOT HIGH ENOUGH TO FOLLOW THIS
SOLUTION RIGHT NOW. THE ELEVATED FRONT SHOULD LIFT NORTH OF THE
REGION WEDNESDAY AFTERNOON...BUT INCREASING INSTABILITY AND THE
APPROACH OF THE SFC WARM FRONT SHOULD CAUSE ADDITIONAL STORMS TO
DEVELOP IN OUR SW COUNTIES LATER WEDNESDAY AFTERNOON. INSTABILITY
AND SHEAR WILL BE FAIRLY WEAK...SO TSTMS SHOULD REMAIN WELL BELOW
SEVERE LIMITS.

USED A BLEND OF THE BETTER PERFORMING GUIDANCE SETS FOR TEMPS THE
NEXT COUPLE DAYS. EXPECT MAINLY 60S FOR HIGH TEMPS TODAY...WITH
50S NEAR LAKE MICHIGAN AND SOME LOWER 70S OVER FAR NORTHERN WI.
ON WEDNESDAY...HIGH TEMPS SHOULD REACH THE UPPER 60S TO MIDDLE
70S...EXCEPT 50S NEAR LAKE MICHIGAN.

.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY
ISSUED AT 327 AM CDT TUE MAY 5 2015

SPLIT FLOW ALOFT WILL TRANSITION TO A MORE AMPLIFIED WEATHER
PATTERN THIS WEEKEND INTO THE BEGINNING OF NEXT WEEK...WITH
SEVERAL CHANCES BUT LITTLE MODEL AGREEMENT ON TIMING AND COVERAGE
OF PCPN.

MODELS HAVE BACKED OFF PCPN CHANCES SOMEWHAT WEDNESDAY NIGHT.
WITH A SIGNIFICANT AMOUNT OF DRY AIR AND A LACK OF FORCING OVER
THE STATE...TRENDED TOWARDS THIS DRIER SOLUTION AND DECREASED POPS
WEDNESDAY NIGHT. WOULDNT BE SURPRISED IF IT TURNED OUT TO BE DRY
WEDNESDAY NIGHT.

THURSDAY SHOULD START OUT DRY...WITH GUSTY WINDS POSSIBLE AS DEEP
MIXING DEVELOPS EARLY THURSDAY AFTERNOON. BUMPED UP WIND GUSTS
THURSDAY AFTERNOON FROM PREVIOUS FCST.

A COLD FRONT WILL THEN CROSS THE GREAT LAKES REGION THURSDAY
AFTERNOON INTO FRIDAY. MODEL TIMING AND PCPN COVERAGE AHEAD OF THIS
FEATURE CONTINUES TO REMAIN INCONSISTENT THURSDAY
AFTERNOON...THOUGH MANY OF THE MODELS HAVE SPED UP THE ARRIVAL
OF THE FRONT AND DEVELOPMENT OF PCPN. APPLIED THIS TREND TO
FCST...WITH WEIGHT GIVEN TO THE 00Z ECMWF WHICH SHOWED SOME RUN TO
RUN CONSISTENCY AND WAS A POSSIBLE COMPROMISE OF ALL THE
SOLUTIONS. SHOWERS AND THUNDERSTORMS SHOULD DEVELOP AHEAD OF THE
FRONT LATE THURSDAY AFTERNOON...THEN OVERSPREAD THE REGION THROUGH
THURSDAY NIGHT INTO FRIDAY MORNING WITH THE AID OF THE FRONTAL PASSAGE.
THURSDAY AFTERNOON THUNDERSTORMS COULD BE ON STRONG SIDE IF THEY
DO DEVELOP AS SOME MODELS ADVERTISE INCREASING INSTABILITY AND
MODERATE SHEAR...THOUGH A WIDESPREAD SEVERE THREAT DOESNT LOOK
LIKELY AT THIS TIME.

AFTER THE COLD FRONT EXITS THE CWA FRIDAY
MORNING...THE WEATHER PATTERN BECOMES MORE ACTIVE STARTING THIS
WEEKEND INTO THE BEGINNING OF NEXT WEEK. SEVERAL ROUNDS OF
WIDESPREAD PCPN ARE POSSIBLE...WITH NOT MUCH MODEL AGREEMENT AND
THEREFORE NO REAL DETAIL ADDED TO THE FCST. SUNDAY LOOKS TO BE THE
BETTER CHANCE THROUGH THIS PERIOD...WITH MODELS SHOWING BETTER
FORCING AND SUBSTANTIAL/WIDESPREAD RAINFALL DEVELOPING SUNDAY INTO
MONDAY.

TEMPERATURES SHOULD BE WELL ABOVE NORMAL THURSDAY AND FRIDAY AS A
WARM FRONT LIFT NORTHS AND UPPER LEVEL RIDGING ALLOWS VERY WARM
AIR TO SURGE INTO AREA. TEMPS WILL THEN DROP BACK CLOSER TO NORMAL
BEHIND THE COLD FRONT FOR THE WEEKEND INTO NEXT WEEK.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1254 PM CDT TUE MAY 5 2015

FORECAST CONFIDENCE DROPS THROUGHOUT THIS TAF VALID PERIOD. HIGH
CONFIDENCE THAT VFR CONDITIONS WILL PREVAIL ACROSS MOST OF THE
AREA TODAY. PRECIPITATION AND MAINLY MVFR CIGS WIDESPREAD ACROSS
SOUTHERN WISCONSIN EARLY THIS MORNING REMAINED IN THAT PART OF
THE STATE TODAY AS THE FRONTAL BOUNDARY ACROSS ILLINOIS REMAINS
NEARLY STATIONARY. SO FAR ONLY MID/HIGH CLOUDS HAVE BEEN MOVING
ACROSS THE SOUTHERN ONE-THIRD OF THE FORECAST AREA.

THE WESTERN PART OF THE FRONT IS EXPECTED TO MOVE NORTH AS SOME
MID LEVEL SHORT WAVE ENERGY PASSES...SO HAVE SOME RAIN CHANCES IN
FOR LATE TONIGHT INTO WEDNESDAY MORNING FOR THE AREA. STILL QUITE
A BIT OF DRY AIR IN PLACE SO THERE WILL PROBABLY BE MVFR CIGS BUT
NOT SURE ABOUT TIMING OF PRECIPITATION OR IF IT WILL END UP
REDUCING VSBYS.
&&

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

$$

SHORT TERM.....KIECKBUSCH
LONG TERM......ALLEN
AVIATION.......MG






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