Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 260321
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1021 PM CDT MON APR 25 2016

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.UPDATE...
ISSUED AT 239 PM CDT MON APR 25 2016

.MESOSCALE UPDATE...NO CHANGE TO PRECIPITATION TRENDS FOR THIS
AFTERNOON AND EVENING BUT FOCUS OF CONVECTION AND CONCERN TURNING
TO THE WARM FRONT MOVING GRADUALLY TOWARD THE FORECAST AREA. WHILE
SOUTH TO SOUTHWEST WINDS WERE NOTED JUST SOUTH OF WOOD AND PORTAGE
COUNTIES. NORTHEAST WINDS OVER CENTRAL WISCONSIN WERE LIKELY
PRODUCING A HEALTHY REGION OF CONVERGENCE NEAR THE WARM FRONT.
SCATTERED SHOWERS AND STORMS WERE DEVELOPING OVER THIS REGION AND
ITS POSSIBLE A BRIEF SEVERE STORM OR SPIN UP COULD DEVELOP THE
NEXT HOUR OR TWO. SURFACE DEWPOINTS WERE LOWERING SO THE WINDOW OF
OPPORTUNITY IS LESSONING OVER CENTRAL AREAS. THIS BOUNDARY COULD
BE FOCUS OF ACTIVITY FOR THE REST OF THE AFTERNOON AND EARLY
EVENING OVER EAST CENTRAL WISCONSIN...DEPENDING ON LOCATION NEXT
SEVERAL HOURS.
&&

.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 205 PM CDT MON APR 25 2016

BANDS OF CONVECTION CONTINUE TO LIFT NORTH OVER THE AREA THIS
AFTERNOON AS A WEAKENING UPPER LOW SYSTEM SLOWLY DRIFTS INTO THE
STATE. A SURFACE WARM FRONT WAS LOCATED OVER SOUTHERN WISCONSIN
AND WAS GRADUALLY WORKING INTO PARTS OF CENTRAL AND EAST CENTRAL
WISCONSIN. SOUNDINGS SUGGEST THE AIR MASS IS DEALING WITH SOME CIN
INITIALLY...BUT SOME BREAKS IN THE CLOUD COVER WAS OCCURRING OVER
EAST CENTRAL WISCONSIN. ANTICIPATE CONVECTION TO INCREASE ALONG
AND AHEAD OF THE FRONT AND OVER NORTHERN WISCONSIN AS THE UPPER
SYSTEM SLIDES OVER. SOME SEVERE POTENTIAL DUE TO SHEAR AND
INSTABILITY AVAILABLE...BUT QUESTION REMAINS ON HOW UNSTABLE THE
AIR MASS WILL GET WITH CONTINUED NORTHEAST FLOW AT THE SURFACE AND
WARM AIR ADVECTION ALOFT HAS ENDED OR ENDING DUE TO THE WEAKENING
UPPER SYSTEM. BETTER INSTABILITY WAS LOCATED IN THE WARM SECTOR
OVER SOUTHERN WISCONSIN.

AFTER THE SYSTEM PCPN DEPARTS TONIGHT...CLOUDS WILL HANG ON
OVERNIGHT INTO TUESDAY AS PROGS SUGGESTS LOWER LAYERS REMAIN
SATURATED. ADDED A PERIOD OF DRIZZLE FOR THE OVERNIGHT HOURS.

A CLEAR TREND FROM THE NORTHEAST EXPECTED LATER TUESDAY AS THE
DRY COOL FLOW FROM THE HUDSON BAY HIGH BEGINS TO DOMINATE.

.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 205 PM CDT MON APR 25 2016

COOL PATTERN TO CONTINUE INTO NEXT WEEKEND AS HUDSON BAY HIGH WILL
DOMINATE THE PATTERN WITH EAST/NORTHEAST/NORTH FLOW. ONE SYSTEM
WILL PASS SOUTH OF THE AREA WEDNESDAY NIGHT INTO THURSDAY...AND
THEN ANOTHER SYSTEM LATER SATURDAY INTO SUNDAY.

FOR TUESDAY NIGHT...WAS THINKING FROST WILL BE A POSSIBILITY IF
WINDS SLACKEN OFF. LATEST MODEL GUIDANCE NOW SUGGESTING WINDS
WILL STAY UP THROUGH THE NIGHT...MAINLY FROM 5 TO 10 MPH AT MOST
SPOTS. DECIDED NOT TO ADD FROST FOR TUESDAY NIGHT DUE TO THE
WINDS REMAINING UP THROUGH THE NIGHT. ON WEDNESDAY...DRY
CONDITIONS WILL PREVAIL THROUGH MOST OF THE DAY. SOME LIGHT RAIN
COULD MAKE INTO WAUSHARA...WOOD AND PORTAGE COUNTIES AROUND
SUNSET.

THE HUDSON BAY HIGH WILL DOMINATE THE WEATHER PATTERN OVER THE FAR
NORTH WEDNESDAY NIGHT AND THURSDAY. THE QUESTION IS HOW FAR NORTH
TO BRING THE RAIN. PREVIOUS FORECAST SEEMED TO HAVE A GOOD HANDLE
AND ONLY MADE MINOR ADJUSTMENTS TO THE PRECIPITATION GRIDS. BIG
DIFFERENCES NOTED BETWEEN THE GFS AND ECMWF NEXT WEEKEND WITH
CHANCES FOR RAIN LATER SATURDAY INTO SUNDAY. PLENTY OF TIME TO
RESOLVE THE DIFFERENCES BETWEEN THE TWO MODELS.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1019 PM CDT MON APR 25 2016

EXPECT PLENTY OF LOW-LEVEL MOISTURE TO LINGER TNGT...RESULTING IN
IFR/LIFR CIGS. THERE SHOULD BE SOME IMPROVEMENT TOMORROW AS DRIER
AIR WORKS INTO THE AREA FM THE NE. THE MAIN QUESTION IS HOW
QUICKLY THE IMPROVEMENT WL OCCUR. PLAN TO STAY PRETTY CLOSE TO A
CONSENSUS OF THE GUIDANCE PRODUCTS...WHICH INDICATE POOR
CONDITIONS LINGERING INTO THE DAY FOLLOWED BY SIGNIFICANT
IMPROVEMENT IN THE AFTN.
&&

.MARINE...
ISSUED AT 205 PM CDT MON APR 25 2016

PERSISTENT GUSTY ENE WINDS AND BUILDING WAVES WILL CONTINUE TO
PRODUCE HAZARDOUS CONDITIONS FOR SMALL CRAFT OVER THE NORTHERN
MARINE ZONES THROUGH TUESDAY.
&&

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

$$

UPDATE.........TDH
SHORT TERM.....TDH
LONG TERM......ECKBERG
AVIATION.......SKOWRONSKI
MARINE.........TDH


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