Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 190349
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1049 PM CDT SAT APR 18 2015

UPDATED AVIATION PORTION FOR 06Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND SUNDAY
ISSUED AT 256 PM CDT SAT APR 18 2015

MAIN FOCUS IN THE SHORT TERM WILL BE PRECIP CHANCES ON SUNDAY.

TONIGHTS FORECAST IS FAIRLY STRAIGHT FORWARD AND WILL REMAIN DRY
AND QUIET. THE STRONG SFC HIGH THAT HAS BEEN SITTING OVER THE
GREAT LAKES REGION THE PAST FEW DAYS WILL SIT JUST TO OUR
EAST...LEAVING WISCONSIN IN A TRANSITION ZONE BETWEEN WEATHER
PATTERNS THROUGH THE NIGHT. THE QUESTION AFTER TONIGHT WILL BE
WHICH FEATURE WILL DOMINATE...THE LOW PRESSURE COMPLEX BEING
EJECTED OUT OF THE SOUTHERN PLAINS OR THY DRY AREA OF HIGH
PRESSURE SLOWLY MEANDERING INTO THE NORTHEAST CONUS. GIVEN MODEL
TRENDS AND AMOUNT OF DRY AIR THAT IS ROOTED IN PLACE OVER THE
REGION...LEANED TOWARDS HIGH PRESSURE WINNING THE BATTLE AND THUS
THE DRIER AND SLOWER SOLUTIONS FOR SUNDAYS PRECIP CHANCES. THIS
LINED UP WELL WITH A MAJORITY OF THE MODELS NEWEST
FORECASTS...WITH THE 12Z GFS BEING THE MORE PROGRESSIVE OUTLIER
BUT STILL SHOWING THE WEAKER TREND FROM PREVIOUS RUNS.

CLOUDS WILL INCREASE TONIGHT AS A WEAK WAA REGIMEN TAKES OVER AND
THE DISTURBANCE STRETCHING FROM MINNESOTA TO THE SOUTHERN PLAINS
SHIFTS TOWARDS THE REGION. KEPT THINGS DRY UNTIL 12Z SUNDAY...AS
WEAK FORCING AND VERY DRY LOW LEVELS WILL PERSIST. AFTER 12Z
SUNDAY...THE FIRST DISTURBANCE IN MINNESOTA MOVES INTO NW WISCONSIN
AND POPS INCREASE. SLOWED DOWN PROGRESSION OF PRECIP CHANCES
SIGNIFICANTLY THROUGH 18Z...WITH THE NORTHWOODS BEING THE BETTER
SPOT OF ANY SHOWERY ACTIVITY AS THEY WILL BE CLOSEST TO THE SFC LOW.
IT WAS HARD TO PUT DETAIL OR CONFIDENCE IN THE FORECAST AFTER 18Z
SUNDAY. MODELS SHOW DIFFERENCES ON HOW WIDESPREAD PRECIP WILL
BECOME...AS ANOTHER SFC LOW OUT OF THE SOUTHERN PLAINS MOVES
TOWARDS LOWER MICHIGAN AND INTERACTS WITH THE LOW SHIFTING
NORTHEAST OUT OF MINNESOTA. STILL COME DRIER AIR TO OVERCOME OVER
THE REGION SUNDAY AFTERNOON...AND BETTER FORCING DOESNT ARRIVE
UNTIL 00Z MONDAY...SO BACKED OFF POPS SLIGHTLY BEFORE RAMPING THEM
UP TOWARDS SUNDAY NIGHT.

GIVEN THE SLOWER PROGRESS OF PRECIP CHANCES SUNDAY
AFTERNOON...RAISED HIGH TEMPERATURES FOR SUNDAY AFTERNOON...MAINLY
OVER THE EAST. WINDS OFF THE LAKE AND BAY WILL STILL KEEP IT
COOLER THAN IT COULD BE...MUCH LIKE WHAT HAPPENED TODAY.

.LONG TERM...SUNDAY NIGHT THROUGH SATURDAY
ISSUED AT 256 PM CDT SAT APR 18 2015

A CLOSED UPPER LOW WILL MOVE SLOWLY FROM LAKE WINNIPEG
TO LAKE SUPERIOR AND THEN STALL OVER THE NORTHERN GREAT LAKES FOR
MUCH OF THE WEEK. JET ENERGY LIFTING NORTH FROM THE CENTRAL PLAINS
SHOULD BRING A DECENT AREA OF RAIN TO THE AREA SUNDAY NIGHT BUT
OTHERWISE EXPECT ONLY SHOWERY PRECIPITATION IN THE CYCLONIC
NORTHWEST FLOW MONDAY THROUGH FRIDAY. TEMPERATURES ALOFT SHOULD BE
COLD ENOUGH FOR SNOW SHOWERS IN THE NORTH AND MAY BE COLD ENOUGH
OVER THE REMAINDER OF THE AREA AT NIGHT. WIND IS TOO WESTERLY FOR
MUCH LAKE EFFECT SNOW IN FAR NORTHCENTRAL WISCONSIN WITH THE
POSSIBLE EXCEPTION OF WEDNESDAY NIGHT. TEMPERATURES WILL BE 5 TO
10 DEGREES BELOW NORMAL FOR MUCH OF THE WEEK.
&&

.AVIATION...FOR 06Z TAF ISSUANCE
ISSUED AT 1014 PM CDT SAT APR 18 2015

CLOUDS WILL CONTINUE TO THICKEN AND LOWER THROUGH THE
NIGHT AND EARLY SUNDAY MORNING AS LOW PRESSURE SYSTEMS APPROACH
FROM THE WEST AND SOUTH. RAIN IS EXPECTED TO BEGIN LATER SUNDAY
MORNING ACROSS THE WEST AND SUNDAY AFTERNOON ACROSS THE EASTERN
TAF SITES. TIMING OF THE RAIN SHOWERS IS A BIT TENUOUS AS THERE
REMAINS SIGNIFICANT DIFFERENCES BETWEEN THE NWP MODELS.
&&

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

$$

SHORT TERM.....ALLEN
LONG TERM......RDM
AVIATION.......KURIMSKI






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