Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 222124
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
324 PM CST THU JAN 22 2015

FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND FRIDAY
ISSUED AT 324 PM CST THU JAN 22 2015

PRECIPITATION TYPE AND AMOUNTS ARE THE PRIMARY CONCERNS DURING
THIS PART OF THE FORECAST. A MID LEVEL SHORT WAVE...A SURFACE
TROUGH ASSOCIATED WITH A LOW PRESSURE SYSTEM PASSING NORTH OF THE
REGION...AND UPPER DIVERGENCE IN THE RIGHT ENTRANCE REGION OF A
DEPARTING UPPER LEVEL JET MAX WILL ALL AID IN THE DEVELOPMENT OF
PRECIPITATION ACROSS WISCONSIN LATE TONIGHT THROUGH FRIDAY. MODELS
WERE IN FAIRLY CLOSE AGREEMENT ON KEEPING THE AREA DRY THROUGH 12Z
FRIDAY. HAVE SOME SLIGHT CHANCE AND LOW END CHANCE POPS IN THE
FORECAST TOWARD MORNING...WHICH BLENDS PRETTY WELL WITH
SURROUNDING FORECAST GRIDS.

MODEL SOUNDINGS FROM BUFKIT INDICATED A DRY LAYER AT RHINELANDER
WHEN PRECIPITATION BEGINS...THOUGH THERE COULD BE BETTER AGREEMENT
ON THE DEPTH OF THE DRY AIR AND AMOUNT OF LIFT. A DEEP DRY LAYER
COULD RESULT IN ICE CRYSTAL SUBLIMATION BEFORE THEY FALL INTO THE
MOIST AND COLD AIR NEAR THE SURFACE. THIS WOULD LEAD ONE TO BELIEVE
THAT FREEZING RAIN WOULD BE THE PRECIPITATION TYPE IF THERE IS
ENOUGH LIFT. HAVE KEPT A MENTION OF SNOW ALONG WITH THE FREEZING
RAIN CHANCES. PRECIPITATION SPREADS ACROSS THE REST OF THE AREA
DURING THE DAY AND SHOULD BE PRETTY MUCH GONE BY 00Z
SATURDAY...WITH THE EXCEPTION OF SOME SLIGHT CHANCE POPS FOR NORTH
CENTRAL WISCONSIN DUE TO POTENTIAL LAKE EFFECT. THE 12Z NAM AND
GFS HAD QPF IN THE NORTH BUT WIND DIRECTION AND DELTA T VALUES DO
NOT SEEM FAVORABLE. EXPECT MOSTLY SNOW FOR CENTRAL...FAR NORTHEAST
AND EAST CENTRAL WISCONSIN DURING THE DAY ON FRIDAY WITH
PRECIPITATION WINDING DOWN IN THE NORTH DURING THE AFTERNOON.
SO...HAVE FREEZING DRIZZLE AND SLIGHT CHANCES FOR SNOW THERE.

.LONG TERM...FRIDAY NIGHT THROUGH THURSDAY
ISSUED AT 324 PM CST THU JAN 22 2015

A LOW PRESSURE SYSTEM WILL DROP SOUTHEAST OUT OF MANITOBA AND DRAG
A COLD FRONT INTO NORTH-CENTRAL AND NORTHEAST WISC ON FRIDAY NIGHT.
THE FRONT WILL DELIVER A LIGHT WINTRY MIX OF PRECIPITATION TO THE
REGION FRIDAY NIGHT. PERIODS OF LIGHT FREEZING DRIZZLE ARE LIKELY
STARTING FRIDAY EVENING AROUND 00Z AS TEMPERATURES DROP TO THE
FREEZING LEVEL AT THAT TIME. THE PRECIPITATION WILL TAPER OFF BY
SATURDAY MORNING EXCEPT IN NORTHERN WISC WHERE LAKE EFFECT PRECIP
COULD LINGER INTO THE DAY ON NORTHWEST WINDS.

AS THE CANADIAN LOW MOVES EAST AND CONSOLIDATES WITH A RAPIDLY
DEVELOPING LOW ALONG THE U.S. EAST COAST ON SATURDAY...A SECOND
CANADIAN LOW WILL DIVE DOWN INTO THE NORTHERN MIDWEST AND BRING A
DECENT CHANCE OF ACCUMULATING SNOW TO THE REGION ON SUNDAY. SNOW
WILL END BY MONDAY MORNING FOR MOST AREAS WITH A CHANCE OF LINGERING
LAKE EFFECT SNOW ALONG THE SHORE OF LAKE MICHIGAN. HIGH PRESSURE
WILL THEN GRADUALLY BUILD OVER THE REGION BY WEDNESDAY...BUT THERE
WILL BE A SLIGHT CHANCE OF LIGHT SNOW FOR MOST AREAS UNTIL THEN.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1203 PM CST THU JAN 22 2015

PLENTY OF UNCERTAINTY DURING THE TAF VALID PERIOD. BASED ON
UPSTREAM INVERSIONS AND LOW LEVEL MOISTURE IT WAS QUESTIONABLE
WHETHER THERE WOULD BE MUCH/ANY CLEARING TODAY...BUT MOST OF
NORTHEAST WISCONSIN WAS VFR WITH NO CIGS BY 17Z. SOME OF THE
MODELS KEPT THE CLOUDS WHILE OTHERS HAD SKIES BECOMING CLR OR SCT.
CLOUDS SHOULD RETURN AS A CLIPPER SYSTEM APPROACHES. PRECIPITATION
SHOULD HOLD OFF UNTIL AROUND 12Z IN NORTH CENTRAL WISCONSIN BUT
TYPE IS A BIT OF A PROBLEM. BUFKIT SOUNDINGS AT RHI FROM THE 09Z
SREF/12Z NAM/12Z GFS ALL SHOWED A DRY LAYER AT LEAST 2000FT DEEP
THAT WILL PROBABLY RESULT IN MELTING OF ANY ICE CRYSTALS THAT FORM
ABOVE IT. MODELS SHOWED SOME DIFFERENCES REGARDING LOW LEVEL
MOISTURE AND AMOUNT OF LIFT...BUT WITH A SUBFREEZING MOIST LAYER
OFF THE SURFACE THERE COULD BE SOME FREEZING DRIZZLE WITH WEAK
LIFT. SINCE THERE IS NOT GREAT AGREEMENT ON THIS...HAVE ALSO
MENTIONED SNOW THERE. DEEPER MOISTURE AND STRONGER LIFT SHOULD
KEEP PRECIPITATION MAINLY AS SNOW IN EAST CENTRAL WISCONSIN. CIGS
AND VSBY SHOULD BE MVFR WITH ISOLATED IFR IN PRECIPITATION AND
CLOUDS.

WIND SHEAR IS LIKELY TO BECOME AN ISSUE TONIGHT AND PERSIST INTO
AT LEAST THE MORNING HOURS ON FRIDAY. WINDS AROUND 1500-2000FT AGL
ARE EXPECTED TO BE IN THE 35 TO 45 KNOT RANGE AND THERE IS SOME
DIRECTIONAL SHEAR AS WELL.
&&

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

$$

SHORT TERM.....MG
LONG TERM......ML
AVIATION.......MG





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