Area Forecast Discussion
Issued by NWS Green Bay, WI

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FXUS63 KGRB 311141
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
641 AM CDT TUE MAR 31 2015

UPDATED AVIATION PORTION FOR 12Z TAF ISSUANCE

.SHORT TERM...TODAY...TONIGHT...AND WEDNESDAY
ISSUED AT 326 AM CDT TUE MAR 31 2015

FOG POTENTIAL THIS MORNING...AND PCPN TRENDS THROUGH THE PERIOD...
WILL BE THE MAIN FCST CONCERNS.

THE FIRST ROUND OF PCPN HAD SHIFTED EAST OF THE REGION EARLY THIS
MORNING...BUT THE REGIONAL RADAR MOSAIC SHOWED ANOTHER BATCH OF
SCT SHOWERS OVER THE MN ARROWHEAD...IN ASSOCIATION WITH THE NEXT
SHORT-WAVE TROF. BETWEEN THE TWO SYSTEMS...PARTIAL CLEARING...LIGHT
WINDS...AND ABUNDANT LOW-LEVEL MOISTURE FROM EARLIER RAIN HAS RESULTED
IN AREAS OF FOG...LOCALLY DENSE OVER WESTERN WI.

OFFICES TO OUR WEST HAVE ISSUED DENSE FOG ADVISORIES...BUT PLAN TO
HOLD OFF FOR GRB CWA FOR NOW...AS FOG IS JUST STARTING TO DEVELOP
IN OUR WESTERN COUNTIES...CLEARING IS SPOTTY...AND MORE CLOUDS
OVER NW WI ARE RAPIDLY SPREADING TOWARD THE FORECAST AREA. SUSPECT
THAT BRIEF 1/4-1/2SM VSBYS WILL OCCUR AT SEVERAL LOCATIONS...BUT
MAY NOT BE WIDESPREAD OR PERSISTENT ENOUGH FOR AN ADVISORY. WILL
MONITOR OVER THE NEXT COUPLE HOURS...AND IF NEEDED THERE WILL
STILL BE TIME TO GET A HEADLINE OUT BEFORE THE MORNING COMMUTE.

NEXT S/W TROF OVER FAR SW ONTARIO WILL BRUSH THROUGH NE WI TODAY.
A FEW RAIN OR SNOW SHOWERS MAY AFFECT NC WI EARLY IN THE DAY...
WITH SCT SHOWERS OVER FAR NE WI FROM LATE MORNING THROUGH MID-
AFTERNOON.

A LLJ WILL DEVELOP TONIGHT...AND BECOME FOCUSED OVER EASTERN MN
AND NW WI OVERNIGHT. THERE MAY BE ENOUGH WAA TO GENERATE ISOLD
RAIN/SNOW SHOWERS OVER NC WI LATE. THE LLJ WILL INCREASE TO 45 TO
55 KTS AND BE SITUATED OVER GRB CWA ON WEDNESDAY. THOUGH DEEP
SATURATION IS NOT EXPECTED...ENOUGH FORCING...MOISTURE AND MID-LEVEL
INSTABILITY (H7-H5 LAPSE RATES OF 7-7.5 C/KM) SHOULD BE PRESENT TO
PRODUCE SCT SHOWERS OVER NORTHERN WI. CANNOT RULE OUT ISOLD TSTMS...
BUT CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE RIGHT NOW. A MUCH
BETTER CHANCE OF THUNDER IS ANTICIPATED WITH THE COLD FRONTAL
PASSAGE WED NGT.

USED A BLEND OF THE BETTER PERFORMING GUIDANCE SETS FOR TEMPS THE
NEXT COUPLE DAYS. LOOKING FOR HIGHS IN THE UPPER 40S TO MID 50S
TODAY...AND 50S TO MIDDLE 60S ON WEDS (COOLER NEAR LAKE MICH).
LOW TEMPS TONIGHT SHOULD RANGE FROM THE MIDDLE TO UPPER 20S
NORTH...TO THE LOW TO MID 30S SOUTH.

.LONG TERM...WEDNESDAY NIGHT THROUGH MONDAY
ISSUED AT 326 AM CDT TUE MAR 31 2015

A PROGRESSIVE MEAN FLOW IS EXPECTED ACROSS THE CONUS THRU THE
UPCOMING WEEKEND WHICH TRANSLATES TO A RATHER ACTIVE PATTERN
IMPACTING NE WI. SEVERAL WEATHER SYSTEMS OF VARIOUS STRENGTHS TO
BRING PCPN CHCS TO THE REGION WITH THE WED NGT/THU SYSTEM BEING
THE STRONGEST. MAIN FCST CHALLENGE TO BE TIMING OF THESE SYSTEMS
THRU THE FAST FLOW ALOFT. TEMPS ARE EXPECTED TO RISE AHEAD OF EACH
SYSTEM...THEN COOL DOWN BEHIND EACH SYSTEM. OVERALL...TEMPS WL
LIKELY END UP SLIGHTLY ABOVE NORMAL DURING THE EXTENDED PERIOD.

AN ACTIVE 18-HOUR PERIOD BEGINS WED EVENING AS A CDFNT BEGINS TO
MARCH ACROSS WI. A BROAD SW WIND TO BE IN PLACE AHEAD OF THE FNT
WITH THE MODELS INDICATING A 50-60 KT LOW-LEVEL JET AIMED AT THE
GREAT LAKES. GULF MOISTURE WL HAVE NO TROUBLE REACHING WI WITH
MODELS SHOWING PW VALUES GREATER THAN 1". PLENTY OF LIFT EVIDENT
BETWEEN THE FNT ITSELF AND THE RIGHT ENTRANCE REGION OF THE UPR
JET. ALL INDICATIONS POINT TO AN INCREASING CHC OF RAIN SHWRS
WHICH IS MUCH NEEDED CONSIDERING HOW DRY MARCH HAS BEEN. AS FOR
THUNDER POTENTIAL...THERE ARE STEEP MID-LEVEL LAPSE RATES AND 8H
LI`S DO DROP TO AROUND ZERO. HAVE KEPT A SMALL CHC OF THUNDER IN
THE FCST FOR NOW. A MILD NGT TO SAY THE LEAST WITH MIN TEMPS ONLY
FALLING INTO THE LWR TO MID 40S NORTH...MID TO UPR 40S SOUTH.

CDFNT STILL IN PROCESS OF MOVING THRU ERN WI THU MORNING...THUS
LIKELY POPS NECESSARY IN THE EAST. POPS TAIL OFF TOWARD CNTRL WI
AS THE MODELS SHOW A DRY SLOT/SUBSIDENCE PUSHING INTO WI. RETURN
OF SUNSHINE FROM WEST TO EAST IN THE AFTERNOON SHOULD STILL ALLOW
TEMPS TO WARM...ESPECIALLY AFTER THE MILD START TO THE DAY. LOOK
FOR MAX TEMPS TO RANGE FROM THE MID 50S NEAR LAKE MI...TO THE UPR
50S TO LWR 60S ELSEWHERE.

THE PASSAGE OF A SECONDARY CDFNT AND A MID-LEVEL SHORTWAVE TROF WL
BRING AN END TO THE MILD TEMPS AS 8H TEMPS FALL INTO THE 5 BELOW
TO 10 BELOW ZERO RANGE BY 12Z FRI. SINCE ALL THE LOW-LEVEL
MOISTURE HAD BEEN STRIPPED AWAY BY THE FIRST CDFNT...DO NOT EXPECT
ANY PCPN TO FALL WITH THESE WEATHER FEATURES. HOWEVER...WL HAVE TO
WATCH VILAS CNTY AS WINDS TURN NW AND A FEW LAKE EFFECT SNOW SHWRS
OR FLURRIES CANNOT COMPLETELY BE RULED OUT. MIN TEMPS TO RANGE
FROM THE UPR 20S OVER N-CNTRL WI...TO THE MID 30S ACROSS E-CNTRL
WI.

AS A BROAD AREA OF HI PRES BUILDS INTO THE WRN GREAT LAKES ON FRI...
THIS SHOULD KEEP ANY PCPN TO OUR SOUTH AS A SFC WAVE MOVES ALONG THE
ORIGINAL CDFNT ACROSS THE OHIO RIVER VALLEY/ERN GREAT LAKES. ANY
LINGERING LAKE EFFECT THREAT FOR VILAS CNTY WL END AS THE HI PRES
APPROACHES AND DRIER AIR ADVECTS INTO THE REGION. MAX TEMPS TO BE
BELOW NORMAL ON FRI WITH READINGS ONLY REACHING THE UPR 30S TO LWR
40S NORTH/NEAR LAKE MI...MID TO UPR 40S SOUTH.

MODELS THEN FCST A WEAK...BUT FAST-MOVING CLIPPER SYSTEM TO APPROACH
THE WRN GREAT LAKES LATE FRI NGT AND RACE ACROSS NRN SECTIONS OF THE
GREAT LAKES ON SAT. AS ONE WOULD EXPECT...THE MODELS HAVE SERIOUS
TIMING ISSUES WITH THE LOCATION OF THIS CLIPPER WHICH IMPACT PCPN
CHCS. GULF MOISTURE IS PRACTICALLY NON-EXISTENT WITH THIS SYSTEM...
THUS ANY PCPN THAT DOES FALL WL BE VERY LIGHT. HAVE FOCUSED A
MINIMAL POP ON SAT FOR NOW...BUT THIS WL LIKELY BE UPDATED AS WE
GET CLOSER TO SAT. THE ARRIVAL OF SLIGHT WARMER AIR ALOFT SHOULD
ALLOW MAX TEMPS TO REACH THE LWR 40S FAR NORTH...LWR 50S OVER
PARTS OF CNTRL WI.

THE GRADUAL DEVELOPMENT OF A WEST COAST UPR TROF LATE THIS WEEKEND
INTO EARLY NEXT WEEK COULD BRING AN ACTIVE PERIOD OF WEATHER TO NE
WI. MUCH OF THE FOCUS WL DEPEND ON THE LOCATION OF A QUASI-STNRY
FNT THAT WL STRETCH FROM THE NRN/CNTRL PLAINS E-SE THRU SRN
SECTIONS OF THE GREAT LAKES. INCREASING SW WINDS WL BRING UP GULF
MOISTURE WITH A BAND OF RAIN OR EVEN A RAIN/SNOW MIX SETTING UP
ALONG/JUST NORTH OF THIS FRONTAL BOUNDARY. HAVE FOLLOWED THE
CONSENSUS SOLUTION FOR THE TIME BEING AND MENTION A CHC POP
EVERYWHERE FOR SUNDAY NGT AND MON.
&&

.AVIATION...FOR 12Z TAF ISSUANCE
ISSUED AT 634 AM CDT TUE MAR 31 2015

PARTIAL CLEARING...LIGHT WINDS AND ABUNDANT LOW-LEVEL MOISTURE FROM
LAST NIGHTS RAIN HAS RESULTED IN AREAS OF FOG IN NC/C WI. PATCHY
LIFR/VLIFR CONDITIONS WILL LIKELY LINGER FOR A FEW HOURS AT THE
RHI/AUW/CWA TAF SITES...FOLLOWED BY QUICK IMPROVEMENT. OTHERWISE...
A CLIPPER LOW PRESSURE SYSTEM AND ASSOCIATED UPPER LEVEL DISTURBANCE
AND COLD FRONT...WILL BRING SCT SHOWERS TO NE WI THROUGH THE
AFTERNOON.
&&

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

$$

SHORT TERM.....KIECKBUSCH
LONG TERM......KALLAS
AVIATION.......KIECKBUSCH





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