Area Forecast Discussion
Issued by NWS Green Bay, WI

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
121
FXUS63 KGRB 291707
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1207 PM CDT FRI APR 29 2016

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 339 AM CDT FRI APR 29 2016

THE UPPER LOW WILL MOVE EAST OF WISCONSIN AROUND
DAYBREAK AND TAKE ANY REMAINING SHOWERS WITH IT. DESPITE THE EXIT
OF THE UPPER SYSTEM CLEARING WILL PROBABLY BE SLOW DUE TO CYCLONIC
UPPER FLOW AND SOME REMAINING UPSTREAM JET ENERGY. HIGHS TODAY
SHOULD BE AROUND FIVE DEGREES BELOW NORMAL.

SOME CLEARING IS LIKELY TONIGHT AND THERE IS SOME POSSIBILITY OF A
FREEZE IN THE NORTH AND A FROST IN THE SOUTH. THERE WILL LIKELY BE
SOME WIND IN THE BOUNDARY LAYER ACROSS THE SOUTH WHICH MAY PREVENT
A FROST SO WILL NOT ISSUE ANY ADVISORIES RIGHT NOW. LOWS TONIGHTWILL
BE AROUND FIVE DEGREES BELOW NORMAL.

SATURDAY WILL START OUT SUNNY BUT CLOUDS WILL INCREASE AS THE NEXT
UPPER SYSTEM APPROACHES FROM THE PLAINS STATES. ANY RAIN
ASSOCIATED WITH IT SHOULD HOLD OFF UNTIL AFTER DARK IF IT DOES
MATERIALIZE. HIGHS WILL BE CLOSE TO NORMAL EXCEPT NEAR THE LAKEAND
BAY WHERE A NORTHEAST WIND WILL KEEP IT COOLER.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 339 AM CDT FRI APR 29 2016

MEAN FLOW IS EXPECTED TO TRANSITION FROM BLOCKY IN NATURE TO AN
INCREASINGLY MORE AMPLIFIED PATTERN CONSISTING OF AN EASTERN
PACIFIC UPPER TROUGH...WESTERN NOAM UPPER RIDGE AND AN EVENTUAL
EAST-CENTRAL NOAM UPPER TROUGH. INITIALLY...WE WILL STILL BE
DEALING WITH A CENTRAL CONUS SYSTEM THAT COULD BRING A FEW SHOWERS
TO PARTS OF NE WI SATURDAY NIGHT. ONCE THIS SYSTEM CLEARS...A
COUPLE OF DRY DAYS ARE EXPECTED BEFORE THE EVENTUAL NW FLOW ALOFT
SENDS A COLD FRONT INTO THE REGION TUESDAY OR TUESDAY NIGHT WITH
THE NEXT CHANCE FOR PRECIPITATION. TEMPERATURES WILL FINALLY WARM
TO AT LEAST NORMAL NEXT WEEK (IF NOT SLIGHTLY ABOVE) WITH MORE
SUN AND A WIND NOT OFF OF COLD LAKE MI.

A BROAD...POSITIVE-TILTED UPPER TROUGH IS EXPECTED TO EXTEND FROM
EASTERN CANADA SW ALL THE WAY TO THE SW CONUS SATURDAY NIGHT.
WITHIN THIS UPPER TROUGH...A CLOSED UPPER LOW WILL BE SITUATED
OVER THE CENTRAL PLAINS AND A WAVY QUASI-STATIONARY FRONT TO
STRETCH FROM THE CENTRAL PLAINS EASTWARD THROUGH THE OHIO RIVER
VALLEY WITH SEVERAL WEAK SURFACE WAVES MOVING ALONG THIS FRONT.
QUESTION FOR SATURDAY NIGHT REMAINS HOW FAR NORTH CAN ANY
PRECIPITATION GET BEFORE RUNNING INTO A PREVAILING DRY NE FLOW
OVER WI. THE ECMWF REMAINS FARTHER NORTH WITH THE PRECIPITATION
(UP TO HWY 29)...WHILE THE GFS MAINTAINS ANY PRECIPITATION WOULD
NOT GET PAST SOUTHERN WI. PREFER TO ONLY MENTION A SLIGHT CHANCE
POP FOR OUR SOUTHERN TIER OF COUNTIES (SOUTH OF A MARSHFIELD TO
KEWAUNEE LINE) AND DRY ELSEWHERE WITH MOSTLY CLEAR SKIES FAR
NORTH. MIN TEMPERATURES TO RANGE FROM THE LOWER TO MIDDLE 30S FAR
NORTH...TO THE UPPER 30S TO AROUND 40 DEGREES SOUTH.

THIS ENTIRE SYSTEM IS FORECAST TO GET PUSHED SOUTH BY A LARGE AREA
OF HIGH PRESSURE BUILDING SOUTHWARD FROM CANADA ON SUNDAY. THIS
SHOULD PROVIDE FOR MOSTLY SUNNY SKIES NORTH AND PARTLY CLOUDY
SKIES SOUTH WITH DRY CONDITIONS THROUGHOUT THE FORECAST AREA. WE
WILL STILL HAVE A NE COMPONENT TO THE WIND...THUS EASTERN WI WILL
CONTINUE TO BE COOLER THAN INLAND LOCATIONS. LOOK FOR MAX
TEMPERATURES TO RANGE FROM THE LOWER TO MIDDLE 50S NEAR LAKE MI...
TO THE LOWER 60S OVER PARTS OF CENTRAL WI.

THIS EXPANSIVE AREA OF HIGH PRESSURE TO EXTEND OVER THE WESTERN
GREAT LAKES SUNDAY NIGHT...PROVIDING FOR MOSTLY CLEAR SKIES...
LIGHT WINDS AND COOL CONDITIONS FOR EARLY MAY. IF THE WINDS CAN
COMPLETELY DECOUPLE...TEMPERATURES OVER CENTRAL/EAST-CENTRAL WI
MAY COOL ENOUGH TO ALLOW PATCHY FROST TO FORM. WE WILL NEED TO
WATCH THIS POTENTIAL IN THE COMING DAYS. OTHERWISE...LOOK FOR MIN
TEMPERATURES TO RANGE FROM AROUND 30 DEGREES FAR NORTH-CENTRAL...
TO THE MID TO UPPER 30S SOUTH. AS THE MEAN FLOW BEGINS TO AMPLIFY
ON MONDAY...THE NET RESULT WILL BE A NW FLOW ALOFT INTO WI. THE
GFS ATTEMPTS TO SEND A WEAK SHORTWAVE TROUGH SOUTHEASTWARD INTO
THE GREAT LAKES WITH A SMALL CHANCE FOR LIGHT RAIN SHOWERS. THIS
IS SOMETHING NEW...THAT NEITHER THE GEM NOR THE ECMWF PICK UP...
THUS HAVE IGNORED THE GFS FOR NOW ON MON AND KEEP OUR FORECAST DRY
WITH THE AREA OF HIGH PRESSURE SITUATED JUST TO OUR SOUTH. OTHER
THAN MAX TEMPERATURES HOLDING IN THE MID 50S NEAR LAKE MI...
EXPECT TO SEE READINGS MAINLY IN THE 60-65 DEGREE RANGE ELSEWHERE.

THE NEXT FORECAST CONCERN ARRIVES ON TUESDAY AS BOTH THE GFS AND
GEM SEND A COLD FRONT SOUTHWARD INTO NORTHERN SECTIONS OF THE
GREAT LAKES. THE ECMWF IS ABOUT 12 HOURS SLOWER AND STILL HAS THE
FRONT NORTH OF LAKE SUPERIOR BY 00Z WEDNESDAY. AT THIS POINT...
CANNOT RULE OUT ANY SOLUTION AND WILL KEEP SLIGHT CHANCE POPS IN
THE FORECAST OVER NORTHERN WI WHERE STRONGER CONVERGENCE/BETTER
LIFT TO BE SITUATED. TUESDAY COULD END UP BEING THE WARMEST DAY OF
THE EXTENDED FORECAST DEPENDING ON THE LOCATION OF THE COLD FRONT.
MAX TEMPERATURES COULD GET INTO THE LOWER 60S NEAR LAKE MI...TO
THE UPPER 60S INLAND...WITH LOWER 70S POSSIBLE OVER THE WARMER
LOCATIONS OF CENTRAL WI.

CHANCES FOR RAIN SHOWERS WOULD THEN CONTINUE THROUGH TUESDAY NIGHT
AS THE COLD FRONT DROPS SOUTH THROUGH THE STATE. BETTER UPPER
SUPPORT WOULD FAVOR EASTERN WI WITH SLIGHTLY HIGHER POPS.
OTHERWISE...COOLER AND SOMEWHAT BREEZY CONDITIONS ARE EXPECTED
OVER THE REGION ON WEDNESDAY AS 8H TEMPERATURES FALL INTO THE ZERO
TO +5C RANGE (BELOW ZERO IF YOU BELIEVE THE GFS). MAX TEMPERATURES
ON WEDNESDAY SHOULD DROP BACK INTO THE MID 50S TO LOWER 60S RANGE.

AN AREA OF HIGH PRESSURE IS FORECAST TO MOVE ACROSS THE GREAT
LAKES BY NEXT WEDNESDAY NIGHT/THURSDAY...KEEPING TEMPERATURES A
BIT BELOW NORMAL. MAY HAVE TO WATCH FOR PATCHY FROST ONCE AGAIN
WEDNESDAY NIGHT AS TEMPERATURES FALL INTO THE 30S.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1207 PM CDT FRI APR 29 2016

SCATTERED TO BROKEN CLOUD COVER WILL CONTINUE ACROSS THE
TAF SITES THROUGH THE AFTERNOON HOURS.  CIGS WILL GRADUALLY RISE
THROUGH THE DAY...ENDING ANY MVFR CIGS OVER CENTRAL WI BY EARLY THIS
AFTERNOON.  CLOUDS ARE ANTICIPATED TO CLEAR AT MOST LOCATIONS THIS
EVENING FOR A TIME...THEN SOME MODELS ARE INDICATING THAT CLOUDS
WILL GET RECYCLED WEST INTO EAST-CENTRAL WI LATE TONIGHT INTO
SATURDAY MORNING.  ANY CLOUDS LOOK TO REMAIN VFR THOUGH SOME
MVFR CIGS NOT OUT OF THE QUESTION.
&&

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

$$

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.