Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 280136
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
836 PM CDT WED APR 27 2016

NEW INFORMATION ADDED TO UPDATE SECTION

.UPDATE...
ISSUED AT 834 PM CDT WED APR 27 2016

LEAD BAND OF PCPN FALLING APART AS IT ENCOUNTERS VERY DRY AIR AND
GETS STRETCHED IN UPR DEFORMATION ZONE. DON/T THINK WE/LL GET MORE
THAN SPRINKLES TNGT...EXCEPT OVER THE FAR S/SW CORNER OF THE AREA
WHERE SOME PCPN HAS FINALLY MANAGED TO REACH THE GROUND. UPDATED
FCST ADJUSTED ALONG THESE LINES WAS SENT OUT ABOUT 5 MIN AGO.
&&

.SHORT TERM...TONIGHT AND THURSDAY
ISSUED AT 234 PM CDT WED APR 27 2016

THE LATEST RAP ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW OCCLUDED
LOW PRESSURE OVER EASTERN NEBRASKA EARLY THIS AFTERNOON...AND A WARM
FRONT EXTENDING EAST OVER IOWA/SOUTHERN IL/IN/OH.  LIGHT RAIN IS
ARCING NORTHWARD INTO SOUTHWEST WISCONSIN AND NOT SHOWING MANY SIGNS
OF SLOWING DOWN. TO THE NORTH...HUDSON BAY HIGH PRESSURE IS PUSHING
IN VERY DRY AIR ACROSS NORTHERN WISCONSIN...DRIVEN BY GUSTY EAST AND
NORTHEAST WINDS.  AS THE PRECIP ENCOUNTERS THIS VERY DRY
AIRMASS...PRECIP TRENDS ARE THE MAIN FORECAST CONCERN.

TONIGHT...LOW PRESSURE SPINNING OVER NEBRASKA WILL MAKE SLOW
PROGRESS INTO WESTERN IOWA TONIGHT.  AHEAD OF THE LOW...AN ARCING
BAND OF PRECIP WITHIN A THETAE AXIS WILL LIFT NORTH ACROSS SOUTHERN
WI.  BUT AS THIS BAND LIFTS INTO CENTRAL AND EAST-CENTRAL WI...IT
WILL ENCOUNTER INCREASING AMOUNTS OF DRY AIR BELOW 700MB ORIGINATING
FROM A CANADIAN HIGH TO THE NORTH.  THIS AIRMASS WILL BE BONE DRY
OVER THE UPPER PENINSULA AND FAR NORTHERN WI...WITH MODELS SHOWING
RELATIVE HUMIDITIES LESS THAN 10 PCT BETWEEN 925 AND 700MB.  THE 12Z
MESOMODELS THEREFORE INDICATE THAT LEADING PRECIP BAND WILL DIMINISH
LATER THIS AFTERNOON INTO EARLY THIS EVENING AS IT APPROACHES
WOOD/PORTAGE/WAUSHARA COUNTIES.  BUT SOME PRECIP GENERALLY REMAINS
POSSIBLE SOUTH OF ROUTE 29...WITH PRECIP CHANCES SLOWLY EXPANDING TO
THE NORTHEAST THROUGH THE NIGHT.  BEST CHANCES OF PRECIP ACCORDING
TO PROGGED SOUNDINGS WOULD ARRIVE LATE TONIGHT AFTER 09Z.  A COOLING
THERMAL PROFILE SUGGESTS SOME SNOW MAY MIX IN WITH ANY LIGHT RAIN
LATE OVER CENTRAL WI. LITTLE TO NO ACCUMULATIONS ARE EXPECTED
THOUGH.  PRECIP AMOUNTS WILL BE RELATIVELY LIGHT...MOSTLY LESS THAN
A TENTH OF AN INCH.

THURSDAY...THE LOW PRESSURE WILL MOVE EAST OVER NORTHERN IOWA.  THE
DRY AIR WILL LIKELY THWART PRECIP OVER NORTHERN WI...BUT MID-LEVEL
FGEN WILL KEEP A CHANCE OF LIGHT PRECIP OVER CENTRAL AND EAST-
CENTRAL WI THROUGH THE DAY.  BEST CHANCES WILL OCCUR DURING THE
MORNING WHEN SOME SNOWFLAKES COULD MIX IN WITH THE RAIN OVER CENTRAL
THROUGH 15Z.  TEMPERATURES WILL BE COOLER WHERE THERE IS A HIGHER
PRECIP POTENTIAL...AND GENERALLY WARMER OVER NORTHERN WI WHERE TEMPS
WILL TOP OUT IN THE LOWER 50S.

.LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY
ISSUED AT 234 PM CDT WED APR 27 2016

ALTHOUGH AN ACTIVE PATTERN WILL PERSIST ACROSS THE GREAT LAKES
REGION FOR MUCH OF THE EXTENDED...THESE SYSTEMS WILL BE NORTHERN
STREAM SYSTEMS EMBEDDED IN NORTHWEST FLOW WITH LITTLE IN THE WAY
OF MOISTURE TO WORK WITH. THEREFORE ALTHOUGH THESE SYSTEMS WILL
LOOK FAIRLY IMPRESSIVE WITH VIGOROUS MID LEVEL TROUGHS AND PV
ANOMALIES...THE LACK OF MOISTURE WILL KEEP PRECIPITATION CHANCES
FAIRLY LOW WHEN THEY DO TRACK THROUGH. THESE SYSTEMS LOOK TO TRACK
THROUGH FRIDAY EVENING...THEN AGAIN SATURDAY AND SATURDAY
NIGHT...WITH A FINAL ONE TUESDAY AND WEDNESDAY. AS WAS ALLUDED TO
EARLIER THESE SYSTEMS WILL NOT HAVE MUCH MOISTURE TO WORK
WITH...AS MODELS ARE NOT EXACTLY KEYING IN ON A UNANIMOUS SOLUTION
AS SOME SOLUTIONS REMAIN DRY. THEREFORE PRECIPITATION CHANCES WILL
BE TENUOUS DURING THIS TIME PERIOD.

IN BETWEEN THESE SYSTEMS RIDING WILL BRING DRY WEATHER AND
SUNSHINE AT TIMES. SOME COOL AIR COULD BRING FREEZING TEMPERATURES
LATE FRIDAY NIGHT...WHERE SOME FROST IS POSSIBLE ACROSS CENTRAL
WISCONSIN. TEMPERATURES GET ON A SLOW CLIMB FROM THAT POINT
ONWARD...WITH HIGHS GETTING INTO THE 60S BY TUESDAY AND WEDNESDAY.
&&

.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 548 PM CDT WED APR 27 2016

MAIN QUESTION IS HOW FAR N PCPN WL ADVANCE INTO THE FCST AREA
TNGT. THE GLOBAL MODELS...INCLUDING THE ECMWF AND GFS SUGGEST IT
WL MAKE IT AT LEAST TO HWY 29. THE HI-RES AND SHRT RANGE MODELS
ARE ALMOST UNAMIMOUS IN PRETTY MUCH WIPING OUT THE CURRENT BAND OF
RAIN HEADING INTO THE AREA LATER THIS EVENING...WITH JUST SCT
SPRINLKLES LATER TNGT. RADAR TRENDS SEEM TO BETTER SUPPORT THE
LATTER...AS PCPN BAND IS BEGINNING TO NARROW AND WEAKEN AS IT GETS
STRETCHED OUT IN UPR DEFORMATION ZONE. VERY DRY AIR FLOWING SWWD
INTO THE AREA AT LOW-LEVELS ALSO FAVORS THE BAND WEAKENING. SO
WITH PRETTY MUCH JUST SPRINKLES POSSIBLE OVER AN EXTENDED
PERIOD OF TIME...OPTED TO REMOVED THE PCPN FM THE TAFS WITH THIS
ISSUANCE. MAY REINTRODUCE A SHORT PERIOD OF R- IF IT BECOMES
POSSIBLE TO BETTER PINPOINT WHEN THAT WOULD OCCUR.
&&

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

$$

UPDATE.........SKOWRONSKI
SHORT TERM.....MPC
LONG TERM......KURIMSKI
AVIATION.......SKOWRONSKI


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