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 181746
AFDGRB

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
1246 PM CDT FRI JUL 18 2014

UPDATED AVIATION PORTION FOR 18Z TAF ISSUANCE

.SYNOPSIS...
ISSUED AT 402 AM CDT FRI JUL 18 2014

GENERALLY QUIET WEATHER WITH MID-SUMMER-LIKE TEMPERATURES THROUGH
THE WEEKEND...THOUGH A FEW SHOWERS ARE POSSIBLE ACROSS NORTH-
CENTRAL WISCONSIN AT TIMES.

A FAIRLY LOW AMPLITUDE BELT OF WESTERLIES WAS LOCATED OVER CANADA
AND THE FAR NRN CONUS. SOME REMNANTS OF THE OLD GREAT LAKES UPR
TROF STILL LINGERED IN THE ERN CONUS...RESULTING IN WK WNWLY UPR
FLOW ACRS THE FCST AREA. A NEW LNGWV TROF IS EXPECTED TO DEVELOP
NR THE WEST COAST THE NEXT FEW DAYS. IN RESPONSE...UPR ANTICYCLONE
WL CONSOLIDATE OVER THE DESERT SW...FROM WHICH RIDGING WL BUILD
ENEWD TOWARD THE GREAT LAKES REGION. ANOTHER UPR ANTICYCLONE WL
REMAIN OVER THE WRN ATL. BY THE MIDDLE OF NEXT WK...ONLY WK FLOW
WL EXIST ACRS MOST OF THE CONUS WITH THE MAIN WESTERLIES LOCATED
WELL TO THE N. BUT A WEAKNESS IN THE RIDGE WL EXIST BTWN THE 2 UPR
ANTICYCLONES. THERE CONTINUES TO BE VERY GOOD AGREEMENT AMONG THE
MED RANGE MODELS THAT THE WEAKNESS WL EVENTUALLY GROW INTO A LNGWV
TROF POSN...EVENTUALLY FLIPPING THE PATTERN BACK TO A WRN
RIDGE/GREAT LAKES TROF CONFIGURATION BEYOND THE END OF THE FCST
PERIOD.

TEMPS ARE EXPECTED TO EDGE UPWARD EACH DAY DURING THE FIRST HALF
OF THE FCST PERIOD...TO QUITE WARM LEVELS BY EARLY NEXT WK. TEMPS
WL FALL BACK CLOSE TO SEASONAL NORMALS DURING THE LATTER HALF OF
THE PERIOD AS SHRTWVS BEGIN TO AMPLIFY THE WEAKNESS IN THE UPR
RIDGE ENOUGH TO TILT THE UPR FLOW NW...AND BRING A CANADIAN AIR
MASS BACK INTO THE AREA. A RETURN TO BLO NORMAL TEMPS IS LIKELY
BEYOND THE END OF THE FCST PERIOD AS THE GREAT LAKES TROF DEEPENS.

THERE WL BE SOME OPPORTUNITY FOR PCPN OVER MAINLY THE NW PART OF
THE FCST AREA THROUGH THE WEEKEND AS PCPN FM WX SYSTEMS TO THE W
COULD MAKE IT INTO THE AREA BEFORE DISSIPATING. BUT AMNTS/
CONVERAGE WL BE LIMITED. THE NEXT OPPORTUNITY FOR MORE WIDESPREAD
SIG PCPN WL PROBABLY HOLD OFF UNTIL NEXT WK.
&&

.SHORT TERM...TODAY...TONIGHT...AND SATURDAY
ISSUED AT 402 AM CDT FRI JUL 18 2014

TDA WL BE SIMILAR TO YDA. ONCE AGAIN...EXPECT SFC DWPTS TO MIX
DOWN A BIT IN THE AFTN. THE MODELS PRODUCING SCT LGT PCPN THIS
AFTN WERE THOSE WITH DWPTS THAT LOOKED TOO HIGH...SO LIKE YDA...WL
STICK WITH DRY FCST. TEMPS ALOFT WL BE A BIT WARMER...SO MAXES TDA
SHOULD ALSO BE A DEG OR TWO ABV YDA.

THE QUIET WX WL CONT TNGT. WENT WITH BLEND OF TOP PERFORMING
GUIDANCE FOR MINS.

PREV FCST FOR SAT WAS DRY...BASED ON FCST LOGIC SIMILAR TO
TDA...AND THAT IS STILL OKAY FOR MOST OF THE FCST AREA.
HOWEVER...THINGS HAVE BEGUN TO LOOK A LITTLE DIFFERENT FOR N-C WI.
THE NUMBER OF MODELS GENERATING PCPN IN THAT AREA HAS INCREASED...
AND THE 00Z ECMWF HAS NOW JOINED THAT CAMP. SFC DWPTS WL PROBABLY
EDGE UP TOMORROW AS CONTD SLY FLOW WL ALLOW SOME RETURN OF
MOISTURE. AN INSPECTION OF MODEL FCST SOUNDINGS SUGGESTED WARM
LAYER ARND 650 MB WOULD STILL PROVIDE AN EFFECTIVE CAP TO
CONVECTION. THAT WL PROBABLY STILL HOLD FOR MOST OF THE
AREA...BUT N-C WI WL LIKELY COME UNDER THE INFLUENCE OF THE TAIL
OF UPR SHRTWV SWINGING NEWD TOWARD JAMES BAY. WK ASCENT WITH THE
SHRTWV MIGHT BE SUFFICIENT TO REMOVE THE CAP. STILL NOT VERY
EXCITED ABOUT PCPN CHCS WITH MARGINAL MOISTURE AND BEST DYNAMICS
LIFTG WAY NW OF THE AREA...BUT ALSO NO LONGER COMFORTABLE WITH
KEEPING THE DRY FCST. SO...ADDED LOW POPS FOR N-C WI FOR THE AFTN
AND BLED THEM INTO THE EVENING. TEMPS SHOULD ONCE AGAIN WARM A DEG
OR TWO...WHICH FIT WELL WITH BLEND OF TOP PERFORMING GUIDANCE
PRODUCTS.

.LONG TERM...SATURDAY NIGHT THROUGH THURSDAY
ISSUED AT 402 AM CDT FRI JUL 18 2014

THE MAIN CHALLENGE DURING THE LONG TERM IS DETERMINING WHEN AND
WHERE TO INCLUDE POPS.

UPPER LEVEL FLOW IS FORECAST TO BE MAINLY ZONAL LATE THIS WEEK
INTO THE EARLY PART OF NEXT WEEK. SURFACE HIGH PRESSURE TO THE
EAST WILL BRING WARMER AIR INTO THE REGION AS WELL AS AN INCREASE
IN MOISTURE. PRECIPITATION COULD DEVELOP IN INSENTROPIC LIFT WELL
AHEAD OF AN APPROACHING SURFACE SYSTEM AND POTENT UPPER LEVEL
TROUGH. HAVE OPTED TO LEAVE OUT ANY MENTION OF RAIN LATE SATURDAY
NIGHT AND SUNDAY...THOUGH CONFIDENCE LEVEL IS LOW SINCE THE 00Z
ECMWF AND 00Z GEM WERE TRENDING WETTER AND LOOKING MORE SIMILAR TO
THE 00Z GFS. HAVE A SLIGHT CHANCE FOR THUNDERSTORMS SUNDAY AND
MONDAY BEFORE INCREASING TO CHANCE POPS FOR MONDAY NIGHT THROUGH
WEDNESDAY AS A SURFACE COLD FRONT PUSHES THROUGH WISCONSIN AND AN
INTENSE UPPER LEVEL SHORT WAVE MAKES ITS WAY THROUGH THE STATE.
HOWEVER...THERE IS STILL SOME DOUBT REGARDING THE TIMING OF THESE
FEATURES.

EXPECT A WARMING TREND THROUGH THE EARLY PART OF NEXT WEEK...WITH
ABOVE NORMAL HIGH TEMPERATURES. NEAR OR BELOW NORMAL HIGHS ARE
EXPECTED STARTING ON WEDNESDAY.
&&

.AVIATION...FOR 18Z TAF ISSUANCE
ISSUED AT 1239 PM CDT FRI JUL 18 2014

OVERALL...EXCELLENT FLIGHT CONDITIONS EXPECTED THE NEXT 24 HRS
WITH JUST SOME HIGH BASED CU LATE MORNING AND AFTERNOON. IN
NORTHERN WI...AN ISOLATED SHOWER IS POSSIBLE LATE THIS AFTN ALONG
THE BAY BREEZE AS IT MOVES INLAND. AN UPPER DISTURBANCE MOVING
ALONG THE CANADIAN BORDER MAY BRING A FEW SHOWERS SAT AFTN.

&&

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

$$

SYNOPSIS.......SKOWRONSKI
SHORT TERM.....SKOWRONSKI
LONG TERM......MG
AVIATION.......







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