Area Forecast Discussion
Issued by NWS Green Bay, WI

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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

000
FXUS63 KGRB 171803
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1203 PM CST WED DEC 17 2014

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND THURSDAY
ISSUED AT 329 AM CST WED DEC 17 2014

SNOWFALL TRENDS AND AMOUNTS ACROSS FAR NORTHERN WI TODAY...AND CLOUD
TRENDS AND TEMPERATURES THROUGH THE PERIOD...ARE THE MAIN FCST
CONCERNS.

AN UPPER LEVEL LOW WAS SHIFTING EAST THROUGH CENTRAL WI EARLY THIS
MORNING. AN ASSOCIATED DEFORMATION ZONE WAS PIVOTING AND BECOMING
ORIENTED WEST TO EAST ACROSS FAR NORTHERN WI. STEADY SNOW WAS
OCCURRING OVER FAR NE WI...AND WAS GRADUALLY FILLING BACK IN
OVER NC WI...WHERE CONDITIONS WERE ALSO FAVORABLE FOR LAKE
ENHANCEMENT.

UPPER LEVEL FORCING WILL SHIFT EAST THIS MORNING...WITH THE
DEFORMATION ZONE GRADUALLY WEAKENING AS IT SLOWLY SAGS SOUTH.
ANOTHER 1 TO 2 INCHES OF ADDITIONAL SNOW IS POSSIBLE OVER FAR
NORTHERN WI BEFORE IT TAPERS OFF THIS AFTERNOON. SLIGHTLY HIGHER
AMOUNTS ARE POSSIBLE OVER NW VILAS COUNTY DUE TO LAKE EFFECT...SO
WILL KEEP THE WINTER WX ADVSY GOING THERE UNTIL NOON. SNOW WILL
TAPER OFF TO FLURRIES DURING THE LATE AFTERNOON AND EVENING AS THE
WEAKENING DEFORMATION ZONE EXITS AND LAKE EFFECT CONDITIONS BECOME
MORE UNFAVORABLE (WINDS TURN NNE...INSTABILITY WEAKENS DUE TO WAA
AND MUCH DRIER AIR ARRIVES). A SIGNIFICANT SURGE OF DRIER AIR
SHOULD BRING AT LEAST PARTIAL CLEARING FROM NORTH TO SOUTH DURING
THE LATE EVG AND OVERNIGHT. PARTLY CLOUDY SKIES SHOULD PREVAIL ON
THURSDAY AS HIGH PRESSURE BUILDS INTO THE WSTRN GREAT LAKES.

USED A BLEND OF THE BETTER PERFORMING GUIDANCE SETS FOR TEMPS OVER
THE NEXT COUPLE DAYS...WITH SOME DOWNWARD ADJUSTMENTS OVER NORTHERN
WI TONIGHT DUE TO NEW SNOW COVER AND CLEARING.

.LONG TERM...THURSDAY NIGHT THROUGH TUESDAY
ISSUED AT 329 AM CST WED DEC 17 2014

THE LATEST GFS AND ECMWF ENSEMBLE MEAN INDICATES THAT SPLIT FLOW
WILL TRANSITION TO A MORE TYPICAL RIDGE IN THE WEST AND TROUGH IN
THE EAST PATTERN BY EARLY NEXT WEEK.  UNTIL THIS OCCURS...EXPECT
RELATIVELY QUIET AND SEASONABLE WEATHER.  THERE IS SUBSTANTIAL
SPREAD IN THE MEDIUM RANGE MODELS BY 00Z TUESDAY SO WILL HAVE TO
TAKE A GENERAL MODEL COMPROMISE EARLY NEXT WEEK.  OTHERWISE...WILL
RELY ON THE ECMWF.

THURSDAY NIGHT THROUGH FRIDAY NIGHT...HIGH PRESSURE WILL BE MOVING
ACROSS THE REGION THURSDAY NIGHT AND FRIDAY BEFORE MOVING INTO
EASTERN CANADA ON FRIDAY NIGHT.  LIGHT WINDS WITHIN THE HIGH WILL
SUPPORT GOING BELOW GUIDANCE FOR TEMPERATURES THURSDAY NIGHT...BUT
SOME UNCERTAINTY IN REGARDS TO HOW THICK CIRRUS WILL BE.  WILL STAY
CONSERVATIVE AWAY FROM THE COLD SPOTS WHERE DID DROP TEMPS A COUPLE
DEGREES.  THE CIRRUS WILL TEMPORARILY THIN OUT ON FRIDAY WHICH
SHOULD LEAD TO A BRIEF PERIOD OF MOSTLY CLEAR SKIES.  BUT THEN WILL
SEE CLOUDS INCREASE AGAIN LATE FRIDAY AFTERNOON INTO FRIDAY NIGHT
AHEAD OF A PACIFIC SHORTWAVE TROUGH.  PROGGED SOUNDINGS START TO
LOOK SATURATED BY LATE FRIDAY NIGHT...BUT WILL KEEP PRECIP OUT OF
THE FORECAST AS THE MID-LEVEL DRY WEDGE STILL LOOKS SUFFICIENT TO
THWART PRECIP.

REST OF THE FORECAST...THE SHORTWAVE WILL SLOWLY MOVE ACROSS THE
REGION SATURDAY INTO SATURDAY NIGHT. PROGGED SOUNDINGS CONTINUE TO
SATURATE AND WOULD NOT BE SURPRISED TO SEE LIGHT SNOW.  WILL MENTION
TO LATER SHIFTS.  ANY LIGHT SNOW WILL EXIT LATE SATURDAY NIGHT BUT
SOUTHERLY FLOW LOOKS TO KEEP LOW STRATUS AROUND.  BETTER CHANCES OF
PRECIP THEN ARRIVE SUNDAY NIGHT AHEAD OF A DIGGING SHORTWAVE
TROUGH.  PRECIP CHANCES CONTINUE TO IMPROVE INTO MONDAY THOUGH
ENOUGH WARM AIR AROUND COULD LEAD TO A MIX OF RAIN AND SNOW OVER
CENTRAL AND NORTHEAST WISCONSIN. PRECIP TO CONTINUE INTO TUESDAY.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1202 PM CST WED DEC 17 2014

A FEW IFR CIGS/VSBYS ARE POSSIBLE OVER FAR NORTHERN WI (MAINLY
VILAS COUNTY) THROUGH EARLY AFTERNOON AS THE SNOW SHOWERS AND
FLURRIES COME TO AN END AS THE LAKE EFFECT ACTIVITY ENDS. AS THE
SNOW ENDS...CLOUDS WILL BE THE MAIN AVIATION CONCERN FOR LATE THIS
AFTERNOON AND TONIGHT. SCATTERED TO BROKEN CIGS WILL VARY FROM
MVFR TO VFR AS CLOUDS LINGER OVER THE AREA AS AN UPPER LEVEL
DISTURBANCE MOVES INTO LOWER MICHIGAN. KEPT THE IDEA OF SOME
PARTIAL CLEARING OCCURRING OVERNIGHT...ESPECIALLY OVER CENTRAL WI
INTO THE FOX VALLEY. HOWEVER...CONFIDENCE REMAINS LOW ON HOW MUCH
CLEARING WILL OCCUR...AS MODELS CONTINUE TO SHOW QUITE A BIT OF
LOW LEVEL MOISTURE TONIGHT.
&&

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

$$

SHORT TERM.....KIECKBUSCH
LONG TERM......MPC
AVIATION.......BERSCH






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