National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS63 KGRB 011714
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1114 AM CST SAT MAR 1 2014

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SYNOPSIS...
ISSUED AT 340 AM CST SAT MAR 1 2014

VERY COLD THROUGH EARLY NEXT WEEK...THEN MODERATING TEMPERATURES.

SPLIT FLOW BECOMING ESTABLISHED ACRS NOAM...AS WRN RIDGE HAS BEEN
UNDERCUT BY PACIFIC JET. THE EVOLVING SRN STREAM WL BE FAIRLY
ZONAL THROUGH THE WEEK. THEN BY NEXT WEEKEND...THE FLOW WL GAIN
SOME AMPLITUDE AS CONSOLIDATION BEGINS TO OCCUR.

EXPANSIVE ARCTIC AIR MASS COVERS MUCH OF CANADA AND THE NRN
CONUS...THOUGH THE CORE OF THE COLDEST AIR HAS SHIFTED WWD TOWARD
THE CANADIAN PRAIRIE PROVINCES. MASSIVE ANTICYCLONE DROPPING SWD
THROUGH WRN CANADA WL EXPAND ESEWD BENEATH UPR CONFLUENT ZONE
SETTING UP BTWN THE NRN AND SRN STREAMS. THAT WL KEEP ARCTIC AIR
LOCKED IN ACRS THE AREA AND TEMPS WELL BLO NORMAL THROUGH EARLY
NEXT WEEK...THEN READINGS SHOULD FINALLY MODERATE. NUMEROUS WEAK
SYSTEMS WILL BE RIDING EWD IN THE INCREASINGLY ZONAL FLOW ALOFT.
TIMING OF SYSTEMS WL BE DIFFICULT...BUT NONE LOOK CAPABLE OF
PRODUCING ANYTHING BUT LGT PCPN...SO AMNTS WL END UP BLO NORMAL
FOR THE PERIOD.
&&

.SHORT TERM...TODAY...TONIGHT...AND SUNDAY
ISSUED AT 340 AM CST SAT MAR 1 2014

THE FRIGID MORNING TEMPERATURES AND AFTERNOON SNOW YESTERDAY
SERVED AS A NICE CONCISE SUMMARY OF THE NOW-CONCLUDED 3 MONTHS OF
METEOROLGICAL WINTER. VERY COLD AND SNOWY.

SO NOW THAT WE ARE INTO METEOROLOGICAL SPRING WE CAN EXPECT - - -
MORE SNOW AND COLD. SNOW CHANCES TDA WL COME AS UPR JET SHIFTS EWD
DRAGGING RRQ AND AREA OF FRONTOGENETIC FORCING ACRS THE FCST AREA.
STILL PLENTY OF UNCERTAINTY ON THE NRN EXTENT OF THE SNOW BAND...
AND THE REASON IS LIKELY TWO-FOLD. FIRST...EACH MODEL IS A LITTLE
DIFFERENT ON THE EXACT JET STRUCTURE...AND HENCE LCN OF THE RRQ.
SECOND...FORCING IS PRIMARILY/UPPER LEVEL...BUT NLY FLOW AT LOW
LEVELS WL BE FEEDING COLD AND VERY DRY AIR SWD...SO WE END UP WITH
SITN WHERE PCPN IS FALLING FM MID-DECK BUT AT LEAST PARTIALLY
SUBLIMATING BEFORE REACHING THE SFC. USED A BLEND OF THE MODELS AS
A BASIS FOR POPS. THAT FIT PRETTY WELL WITH LCN OF RADAR RETURNS
STREAMING EWD ACRS THE PLAINS EARLY THIS MORNING...THOUGH AS
MENTIONED STILL SOME QUESTION HOW MUCH OF THAT PCPN WL MAKE IT
THROUGH TO THE GROUND. IN ANY CASE...SNOW AMNTS WL BE MUCH LIGHTER
THAN YDA.

ANY PCPN SHOULD PULL OUT OF CENTRAL WI EARLY TNGT...BUT COULD
LINGER ALL NGT IN E-C WI. SOME INDICATIONS ON THE HIGHER RES
MODELS OF A CIRCULATION OVER LAKE MICHIGAN KEEPING SHSN OVER THE
MTW LAKESHORE AREA INTO SUN MORNING. ADJUSTED POPS ACCORDINGLY.

STARTED WITH BLEND OF BEST PERFORMING GUIDANCE FOR TEMPS. TWEAKED
THE N DOWN TNGT AS DON/T THINK GRADIENT WL BE SUFFICIENT TO KEEP
WINDS STIRRING ALL NGT...AND SKYCON WL BE ONLY CI AND MAYBE EVEN
JUST CLR SKIES. TWEAKED E-C WI UP SINCE CLDS LIKELY TO LINGER ALL
NGT.

STILL SOME QUESTIONS ABOUT THE POSSIBLE NEED FOR A WIND CHILL
ADVISORY TNGT. UNCERTAINTY IS WHETHER OR NOT WINDS DIE OFF ACRS
THE N...AND IF TEMPS IN E-C WI WL GET COLD ENOUGH. WL LEAVE IT TO
THE DAY SHIFT TO TAKE ONE MORE LOOK AND MAKE THE FINAL DECISION.

.LONG TERM...SUNDAY NIGHT THROUGH FRIDAY
ISSUED AT 340 AM CST SAT MAR 1 2014

TRANSITION FROM SPLIT FLOW TO NEAR ZONAL TO BE COMPLETE BY THE
MIDDLE OF NEXT WEEK BEFORE THE MEAN FLOW BEGINS TO AMPLIFY LATE
NEXT WEEK WITH ANOTHER WEST COAST UPR RDG AND DOWNSTREAM UPR TROF
OVER THE CNTRL CONUS. THE NEAR ZONAL FLOW WL BRING SEVERAL PACIFIC
SYSTEMS RACING ACROSS THE CONUS WHICH WL MAKE PCPN TIMING
DIFFICULT. THE GOOD NEWS IS THAT TEMPS WL MAKE A GRADUAL RISE WITH
READINGS AT LEAST GETTING A WHIFF OF 30 DEGS BY THU.

A BROAD AREA OF HI PRES IS FCST TO STRETCH FROM THE UPR MS VALLEY
S-SW ALL THE WAY TO CNTRL TX SUNDAY NGT. THE COMBINATION OF MOSTLY
CLEAR SKIES...RELATIVELY LIGHT W-NW WINDS AND AN INFLUX OF DRIER
AIR...SHOULD BRING ANOTHER FRIGID NGT TO NE WI. MAY NEED TO LWR
TEMPS ACROSS THE TYPICALLY COLDER LOCATIONS OF N-CNTRL AND CNTRL
WI WITH SOME LOCATIONS SURPASSING 20 BELOW ZERO ONCE AGAIN. IT
DOES NOT APPEAR THAT WINDS WL COMPLETELY DECOUPLE...THUS
ANTICIPATE THE EVENTUAL NEED FOR A WIND CHILL ADVY WHEN WE GET
CLOSER TO THE EVENT.

THE HI PRES MOVES EWD INTO THE WRN GREAT LAKES/MIDWEST REGIONS ON
MON AND SHOULD BRING A GOOD DEAL OF SUNSHINE TO NE WI FOR MOST OF
THE DAY. THERE MAY BE SOME LATE DAY INCREASE IN HI CLOUDS AS WAA
DEVELOPS WELL TO OUR WEST. DESPITE THE SUNSHINE...MAX TEMPS TO BE
HELD IN CHECK PRIMARILY DUE TO THE BITTERLY COLD START TO THE DAY.
LOOK FOR READINGS TO ONLY REACH THE UPR SINGLE DIGITS TO LWR TEENS.

AS THE MEAN FLOW TRANSITIONS MORE ZONAL BY MON NGT...MDLS BEGIN
TO DIFFER WITH RESPECT TO THE FIRST PACIFIC SYSTEM/WAA TO PUSH
TOWARD WI. THE NAM/ECMWF FAVOR A SLOWER MOVEMENT...WHILE THE
GFS/GEM FAVOR A FASTER MOVEMENT. THIS MEANS THE DIFFERENCE BETWEEN
INCREASING CLOUDS AND LIGHT SNOW OVERSPREADING THE REGION. HAVE
ESSENTIALLY SPLIT THE SOLUTIONS HERE AND WL BRING A CHC OF LIGHT
SNOW TO MOST OF THE FCST AREA AFTER MIDNGT. INCREASING CLOUDS WL
PREVENT TEMPS FROM FALLING NEARLY AS FAR AS SUNDAY NGT WITH MOST
LOCATIONS 5 TO 10 DEGS MILDER. THIS WOULD SEND MIN TEMPS INTO THE
5 BELOW TO 10 BELOW ZERO RANGE N-CNTRL WI...NEAR ZERO LAKESIDE.
THIS WEAK SYSTEM SHOULD PROCEED ACROSS THE GREAT LAKES ON
TUE...THEREFORE WL CONT TO MENTION CHC POPS IN THE FCST. A
SPRAWLING AREA OF HI PRES ACROSS SRN CANADA MAY BE ABLE TO FUNNEL
ENUF DRY AIR INTO NRN TO ONLY BRING FLURRIES INSTEAD OF LIGHT
SNOW. EITHER WAY...THIS LOOKS LIKE A MINOR EVENT WITH MINIMAL
ACCUMULATIONS. MAX TEMPS TO GENERALLY GET INTO THE MID TEENS.

THE LARGE AREA OF HI PRES IS PROGGED TO SETTLE SE INTO ERN ONTARIO/
WRN QUEBEC TUE NGT AND REACH SW QUEBEC ON WED. DRY AIR SHOULD CONT
TO ROTATE AROUND THE SFC HI TOWARD WI ON E-SE WINDS. ONLY CONCERN
WOULD BE POSSIBLE LAKE EFFECT SNOW SHWRS NEAR LAKE MI...BUT AT THIS
POINT IT APPEARS TO SMALL OF A CHC TO INCLUDE IN THE FCST FOR NOW.
THE DEPTH OF THIS HI PRES IS ENUF SUCH THAT POPS MAY BE ABLE TO BE
REMOVED ALTOGETHER. OTHERWISE...THE UPWARD TREND IN TEMPS TO CONT
ON WED WITH READINGS PERHAPS HITTING THE 20 DEG MARK.

THE SECOND PACIFIC SYSTEM HAS SOME OF THE MDLS BRINGING A CHC OF
LIGHT SNOW TO NE WI WED NGT INTO THU. TIMING IS QUITE DIFFICULT
THIS FAR OUT IN TIME...THUS CONFIDENCE IS RATHER LOW. HAVE
FOLLOWED THE CONSENSUS SOLUTION WHICH BRINGS A LOW POP TO THE FCST
AREA DURING THIS TIME FRAME. THE GFS AND ECMWF ARE IN REMARKABLE
AGREEMENT IN SENDING A CDFNT THRU WI ON FRI. THERE DOES APPEAR TO
ENUF MOISTURE TO AT LEAST BRING A CHC OF SNOW TO THE FCST AREA...
BUT THE BIGGER STORY MAY BE THE MAX TEMPS AS SW WINDS AHEAD OF THE
FNT SENDS READINGS INTO THE LWR TO MID 30S.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1113 AM CST SAT MAR 1 2014

ANOTHER ROUND OF LIGHT SNOW WILL SPREAD ACROSS SOUTHERN WISCONSIN
THIS AFTERNOON.  THE NORTHERN EDGE WILL CLIP CENTRAL WISCONSIN BUT
SHOULD REACH INTO EAST-CENTRAL WISCONSIN BY MID TO LATE AFTERNOON.
THE FOX VALLEY AND LAKE SHORE TAF SITES SHOULD SEE VSBYS/CIGS FALL
TO MVFR CONDITIONS...AND POSSIBLY IFR AT MTW FOR A PERIOD.  NOT
EXPECTING MORE THAN AN INCH OF ACCUMULATION THOUGH.  THE MAIN AREA
OF SNOW WILL EXIT BY LATE IN THE EVENING...THEN MODELS ARE DEPICTING
A BAND OF SNOW DEVELOPING OVER LAKE MICHIGAN LATE TONIGHT.  SOME
INDICATIONS THAT THIS BAND WILL BRUSH BY MTW INTO SUNDAY MORNING.
WILL KEEP MVFR CONDITIONS AT MTW THROUGH THEN.
OTHERWISE...CONDITIONS TO TURN VFR ELSEWHERE OVERNIGHT.
&&

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

$$

SYNOPSIS.......SKOWRONSKI
SHORT TERM.....SKOWRONSKI
LONG TERM......KALLAS
AVIATION.......MPC