Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 310000
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
600 PM CST FRI JAN 30 2015

UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND SATURDAY
ISSUED AT 231 PM CST FRI JAN 30 2015

MAIN FCST ISSUES CENTER AROUND SNOW CHCS TNGT ASSOCIATED WITH A
STRONG SHRTWAVE AND APPROACHING CDFNT...AND POTENTIAL FOR LAKE
EFFECT SNOW SHWRS ACROSS N-CNTRL WI AS TRAJS BECOME FAVORABLE FOR
A TIME.

THE 20Z MSAS SFC ANALYSIS INDICATED AN AREA OF HI PRES THAT
STRETCHED FROM THE SRN PLAINS TO THE WRN GREAT LAKES. A RATHER
DIFFUSE AREA OF LOW PRES WAS SITUATED OVER THE NRN PLAINS WITH A
CDFNT ALSO IN THAT GENERAL VCNTY. THERE ALSO APPEARS TO BE A WEAK
WRMFNT THAT EXTENDED ACROSS NRN MN. VSBL SATL IMAGERY AND SFC OBS
SHOWED MAINLY MID/HI CLOUDS OVER THE WRN GREAT LAKES/UPR MS VALLEY
WITH SOME LOW CLOUDS LOCATED OVER NRN MN. SFC OBS ALSO SHOWED SOME
LIGHT SNOW OR FLURRIES IN THE VCNTY OF THE WRMFNT.

THE STRONG SHORTWAVE IS FCST TO MOVE E-SE ACROSS NRN SECTIONS OF
THE GREAT LAKES TNGT...FOLLOWED BY A CDFNT WHICH IS EXPECTED TO
REACH CNTRL WI BY 12Z SAT. STRONGER FORCING TO BE ALONG AND NORTH
OF THE SHORTWAVE TRACK...THUS HIGHEST POPS TO BE NORTH OF THE WI
BORDER. HAVE KEPT CHC POPS GOING ACROSS NRN WI WITH ACCUMULATIONS
HOLDING AT LESS THAN AN INCH. CNTRL/E-CNTRL WI MAY SEE SOME
FLURRIES...BUT NOTHING MORE. CONTINUED WAA INTO WI AHEAD OF THE
CDFNT...COMBINED WITH THICKENING CLOUD COVER...SHOULD KEEP TEMPS
FAIRLY STEADY THRU THE NGT WITH READINGS HOLDING MAINLY IN THE
TEENS.

MODELS LEVELS OF CAA TAKE OVER FOR SAT WITH WINDS SLOWLY VEERING
FROM W-NW TO N-NE DURING THE DAY. THERE IS A POTENTIAL FOR LAKE
EFFECT SNOW SHWRS OVER N-CNTRL WI SAT MORNING INTO THE EARLY
AFTERNOON HOURS WHEN TRAJS BECOME FAVORABLE. PROBLEM FOR A STEADY
SNOW WL BE THE VEERING WINDS...THUS MAKING IT DIFFICULT FOR A
PERSISTENT SNOW BAND TO DEVELOP. IN ADDITION...THE INVERSION
HEIGHTS ARE RATHER LOW (4K FT). THEREFORE...ADDITIONAL
ACCUMULATIONS WL BE VERY MINOR (AROUND ONE-HALF INCH OR LESS).
THE REST OF THE FCST AREA WL SEE A GOOD AMOUNT OF CLOUD COVER AS A
DEVELOPING STORM ORGANIZNES OVER THE SRN PLAINS AND BEGINS TO PULL
GULF MOISTURE NWD. MAX TEMPS TO RANGE FROM AROUND 20 DEGS
N-CNTRL...TO AROUND 30 DEGS E-CNTRL WI.

.LONG TERM...SATURDAY NIGHT THROUGH FRIDAY
ISSUED AT 231 PM CST FRI JAN 30 2015

SEVERAL CHANCES FOR (MAINLY LIGHT) SNOW AND WELL BELOW NORMAL
TEMPS HIGHLIGHT THE LONG TERM.

ALL EYES WILL BE ON THE STORM SYSTEM PASSING SOUTH OF THE AREA
SATURDAY NIGHT AND SUNDAY. 00Z GUIDANCE SHIFTED THE SYSTEM
SLIGHTLY TO THE NORTH...WITH THE 12Z MODELS NOT SHOWING MUCH
CHANGE. SURFACE LOW LOOKS TO TRACK FROM SOUTHERN IL TOWARD WV
MONDAY NIGHT. MID/UPPER LEVEL TROUGH AND SHORTWAVE ENERGY WILL
TRAIL THE SURFACE LOW BY 6-12 HOURS...CROSSING THE SOUTHERN GREAT
LAKES SUNDAY NIGHT. WITH THE CURRENT TRACK...THE HEAVY SNOW BAND
WILL STAY WELL SOUTH THE OF CWA...WITH LIGHT SNOW LIKELY SOUTH OF
A WAUSAU TO STURGEON BAY LINE ON THE NORTHERN FRINGE OF THE
SYSTEM...WITH ACCUMULATIONS RANGING FROM A DUSTING NEAR THE HWY
29 CORRIDOR...TO UP TO 2 OR 3 INCHES SOUTH OF A MARSHFIELD TO
OSHKOSH LINE. SOME DRY AIR WILL BE EATING AWAY AT THE NORTHERN
FRINGE OF THIS SYSTEM...SO LITTLE TO NO SNOW IS EXPECTED NORTH OF
HWY 29...EXCEPT FOR LIGHT LAKE EFFECT ACTIVITY (SEE BELOW). THERE
REMAINS SOME UNCERTAINTY ON THE TRACK AND STRENGTH OF THIS SYSTEM
AS IT JUST PUSHING ASHORE OVER WESTERN BRITISH COLUMBIA AND NOT
WELL SAMPLED BY THE RADIOSONDE NETWORK...PLUS THERE WILL BE SOME
PHASING ISSUES AS IT CROSSES INTO THE OHIO VALLEY. WITH MODELS
FAIRLY CONSISTENT THE PAST TWO RUNS...WILL UP POPS SOUTH OF HWY
29...WITH THE HIGHEST POPS ACROSS SOUTH OF A MARSHFIELD TO
KEWAUNEE LINE...BUT SOME CHANGE IN TRACK (AND SNOW TOTALS) IS
STILL POSSIBLE WITH THE SYSTEM. ADDED SOME PATCHY BLOWING SNOW FOR
SUNDAY ACROSS EAST- CENTRAL WI AS WINDS COULD GUST TO AROUND 25
MPH.

IN ADDITION TO THE SYNOPTIC SNOW...LAKE EFFECT/ENHANCEMENT SNOW
CHANCES WILL BE INCREASING ACROSS EASTERN WI AS WINDS BECOME NE
LATE SATURDAY NIGHT AND SUNDAY. INVERSION HEIGHTS OF
3000-4000FT...DELTA T/S STARTING AROUND 13 AND INCREASING TO
AROUND 16 AND VIRTUALLY NO WIND SHEAR UP TO THE INVERSION SHOULD
PRODUCE SOME BANDS OF SNOW. NEGATIVES WILL BE ICE COVERAGE ON THE
NORTHERN PART OF THE LAKE AND DRIER AIR FILTERING IN FROM THE
EASTERN UP (NAM SHOWING 925-850MB RH NEAR 30%...BUT GFS SHOWING IS
SHOWING MUCH HIGHER MOISTURE AS FLOW COMES OVER LAKE SUPERIOR).
BEST CHANCE FOR ACCUMULATING SNOW LOOKS TO BE SOUTH OF
KEWAUNEE...PEAKING SOUTH OF MANITOWOC. INCREASED POPS AND SNOW
TOTALS SLIGHTLY OVER EASTERN MANITOWOC AND KEWAUNEE COUNTIES.
NE/NW WINDS OFF OF LAKE SUPERIOR WILL BRING SOME LAKE EFFECT
ACTIVITY OVER FAR NORTH-CENTRAL WI FROM TIME TO TIME SATURDAY
NIGHT INTO EARLY MONDAY AM...BUT ACCUMULATIONS LOOK TO BE ON THE
LIGHT SIDE AS SET UP NOT VERY FAVORABLE FOR OUR SNOWBELT AREA.

A COUPLE SYSTEMS WILL MOVE ACROSS THE AREA THE FIRST HALF OF THE
NEW WEEK. THE FIRST WILL BE MONDAY NIGHT...AS A WEAK SHORTWAVE AND
WARM AIR ADVECTION PUSHES ACROSS WI. NOT MUCH PRECIP EXPECTED WITH
THIS SYSTEM. A BETTER CHANCE FOR ACCUMULATING SNOW COMES IN ON
TUESDAY AFTERNOON INTO WEDNESDAY...AS A DIGGING UPPER
TROUGH...SHORTWAVE ENERGY...AND ARCTIC FRONT APPROACH THE REGION.
STILL QUITE A BIT OF TIMING ISSUES WITH THESE FEATURES...SO WILL
NOT INCREASE POPS PAST CHANCE AT THIS TIME...BUT THINK POPS WILL
NEED TO BE INCREASED AT SOME POINT. STRONG CANADIAN HIGH PRESSURE
BUILDS INTO THE GREAT LAKES WEDNESDAY NIGHT AND THURSDAY...WITH
ONLY SOME LAKE EFFECT SNOW OVER FAR NORTH-CENTRAL WI EXPECTED.

WELL BELOW NORMAL TEMPS WILL DOMINATE THE LONG TERM...WITH SURGES
OF COLD/ARCTIC AIR PUSHING INTO THE AREA BEHIND EACH OF THE
SYSTEMS. COLDEST SURGE WILL BE MID-WEEK...AS 850MB TEMPS PLUNGE TO
AROUND -26C.
&&

.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 600 PM CST FRI JAN 30 2015

VFR SHOULD PREVAIL AT LEAST THROUGH THE EVENING HOURS.
SOME SCATTERED TO BROKEN CLOUDS BETWEEN 2000 AND 3000 FEET SHOULD
ACCOMPANY A FRONT THAT WILL MOVE ACROSS THE AREA LATE TONIGHT AND
EARLY SATURDAY. SOME LIGHT SNOW SHOWERS OR FLURRIES ALSO POSSIBLE.
MVFR CEILINGS EXPECTED IN MOST PLACES SATURDAY THOUGH THEY COULD
RISE TO VFR LATER IN THE DAY.
&&

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

$$

SHORT TERM.....KALLAS
LONG TERM......BERSCH
AVIATION.......RDM






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