Area Forecast Discussion
Issued by NWS Green Bay, WI

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000
FXUS63 KGRB 072142
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
442 PM CDT MON JUL 7 2014

UPDATED AVIATION PORTION FOR 00Z TAF ISSUANCE

.SHORT TERM...TONIGHT AND TUESDAY
ISSUED AT 225 PM CDT MON JUL 7 2014

IMMEDIATE CONCERN TO BE SEVERE POTENTIAL LATE THIS
AFTERNOON THRU THE EVENING AS A CDFNT COMBINES WITH A SHORTWAVE
TROF AND JET STREAK ALOFT. LATER CONCERNS TO BE ON EXTENT OF PCPN
AND MAX TEMPS ON TUE AS UNSETTLED WEATHER TO CONT.

THE 19Z MSAS SFC ANALYSIS INDICATED AN AREA OF LOW PRES OVER
ONTARIO WITH A CDFNT EXTENDED SWWD FROM THIS LOW THRU CNTRL MN TO
NE NEBRASKA. ELEVATED TSTMS HAD DEVELOPED THIS AFTERNOON OVER
PARTS OF CNTRL AND WRN WI AS DAYTIME HEATING AND DEW POINTS IN
THE LWR TO MID 60S HAD CREATED ENUF INSTABILITY.

SCATTERED CONVECTION TO SEE A NOTICEABLE INCREASE IN ACTIVITY THRU
THE EVENING AS THE CDFNT INTERACTS WITH AN APPROACHING STRONG
SHORTWAVE TROF AND A 100 KT UPR JET DIVING SE THRU THE MIDWEST.
EVEN THO INSTABILITY IS NOT AS POTENT AS YESTERDAY...THE STRENGTH
OF THE MID-LEVEL FORCING AND THE FAVORABLE LEFT EXIT REGION OF THE
UPR JET SHOULD BRING ANOTHER SWATH OF SHWRS/TSTMS ACROSS NE WI
TNGT. TIMING OF ROUGHLY FROM 22Z-04Z FOR CNTRL WI...00Z-06Z FOR
ERN WI STILL LOOKS GOOD AND HAVE CONTINUED TO HIT THE POPS HARD.
AS FOR THE SEVERE POTENTIAL...CURRENT ACTIVITY ALREADY REACHING
MARGINALLY SEVERE LEVELS AND WITH FORCING/LIFT INCREASING...DO
NOT SEE WHY ACTIVITY WOULD NOT BE ABLE TO MAINTAIN ITS STRONG TO
SEVERE LEVELS THRU THE EVENING. MIN TEMPS TO RANGE FROM THE MID
50S NORTH TO THE LWR 60S SOUTH.

THE BROAD SHORTWAVE TROF TO RESIDE OVER THE GREAT LAKES ON TUE AND
CONTRIBUTE TO STEEP MID-LEVEL LAPSE RATES. THIS COMBINATION OF
CYCLONIC FLOW AND INSTABILITY SHOULD BE SUFFICIENT TO GENERATE AT
LEAST A CHC OF SHWRS/ISOLATED TSTMS ACROSS THE ENTIRE FCST AREA.
MAX TEMPS TO BE A GOOD DEAL COOLER COMPARED TO MON WITH READINGS
ONLY IN THE MID TO UPR 60S FAR NORTH...TO THE MID 70S OVER PARTS
OF CNTRL WI.

.LONG TERM...TUESDAY NIGHT THROUGH MONDAY
ISSUED AT 225 PM CDT MON JUL 7 2014

COOLER TEMPERATURES AT THE BEGINNING OF THE PERIOD AND PCPN TRENDS
FOR NEXT WEEKEND ARE THE MAIN FCST CONCERNS DURING THE EXTENDED
PERIOD.

A STRONG S/W TROF AND THE LFQ OF AN 80 KT JET STREAK WILL IMPACT
THE NE HALF OF THE FORECAST AREA TUESDAY NIGHT...ESPECIALLY DURING
THE LATE EVENING AND EARLY MORNING HOURS. ALTHOUGH INSTABILITY
WILL WANE QUICKLY AFTER SUNSET...STEEP MID-LEVEL LAPSE RATES OF
6-7 C/KM WILL ARRIVE WITH THE S/W TROF...SO WILL KEEP A MENTION
OF ISOLD TSTMS IN THROUGH THE NIGHT. ANY LINGERING SHOWERS SHOULD
EXIT WEDS MORNING...WITH CANADIAN HIGH PRESSURE AND A BUILDING
RIDGE ALOFT EXPECTED DURING THE AFTERNOON. A MUCH COOLER CANADIAN
AIR MASS WILL ARRIVE DURING THE PERIOD...WITH H8 TEMPS DROPPING TO
+4 TO +8 C BY WEDS MORNING...AND ONLY MODERATING SLIGHTLY DURING
THE DAY. HAVE LOWERED MAX TEMPS A FEW DEGREES...WITH READINGS IN
THE MID 60S TO LOWER 70S EXPECTED.

CANADIAN HIGH PRESSURE WILL DOMINATE OUR WEATHER WEDNESDAY NIGHT
THROUGH THURSDAY NIGHT...BRINGING DRY AND PLEASANT WEATHER. CLEAR
SKIES AND LIGHT WINDS ON WEDS NGT WILL RESULT IN COOL TEMPS. HAVE
LOWERED MIN TEMPS BY ABOUT 5 DEGREES...AND WENT WITH LOWER TO
MIDDLE 40S IN THE TYPICAL COLD SPOTS. AN INCREASE IN CLOUD COVER
MAY BE SEEN IN OUR WESTERN COUNTIES LATE THURSDAY NIGHT...BUT PCPN
SHOULD HOLD OFF UNTIL FRIDAY.

MODELS OFFER A VARIETY OF SOLUTIONS WITH REGARD TO PCPN CHANCES
THROUGH THE WEEKEND. THE ECMWF AND GEM BOTH SHOW A WELL-DEFINED
S/W TROF MOVG THROUGH WI ON FRIDAY...ACCOMPANIED BY WIDESPREAD
SHRA/TSRA...WHILE THE GFS HAS THE UPPER LEVEL FORCING SPLITTING
NORTH AND SOUTH OF THE REGION...AND VERY LITTLE QPF. WITH THE
RETURN OF A MORE MOIST AND UNSTABLE AIR MASS...WOULD EXPECT AT
LEAST SCT SHRA/TSRA TO DEVELOP.

A COUPLE COLD FRONTS ARE EXPECTED TO MOVE THROUGH THE FORECAST
AREA OVER THE WEEKEND...THE FIRST ON FRIDAY NIGHT/SATURDAY...AND
THE SECOND ON SUNDAY/SUNDAY NIGHT. MODELS DISAGREE ON THE TIMING
OF THESE FEATURES...SO WILL USE THE BLENDED MODEL GUIDANCE FOR
POPS UNTIL THERE IS A BETTER CONSENSUS.
&&

.AVIATION...FOR 00Z TAF ISSUANCE
ISSUED AT 442 PM CDT MON JUL 7 2014

SHOWERS AND THUNDERSTORMS WILL BE ON THE INCREASE THIS
EVENING AND WILL CONTINUE OVERNIGHT. SCATTERED MVFR CIGS AND VSBYS
CAN BE EXPECTED WITH THE CONVECTION. A STRONG MID-LEVEL SHORTWAVE
TROF WITH COLD FRONT WILL SWEEP OVER THE AREA TONIGHT FOR A FOCUS
FOR THE CONVECTION. IN THE WAKE OF THE CONVECTION OVERNIGHT A
PERIOD OF IFR CIGS COULD DEVELOP LATE TONIGHT AND CONTINUE EARLY
TUESDAY MORNING.  AFTER A PERIOD OF VFR CONDITIONS FOR
TUESDAY...SCATTERED MVFR CIGS POSSIBLY IN THE AFTERNOON WITH
DEVELOPING SHOWERS AND STORMS.
&&

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

$$

SHORT TERM.....AK
LONG TERM......TSK
AVIATION.......TDH






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