225
FXUS63 KGRB 080842
AFDGRB
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREEN BAY WI
242 AM CST SUN NOV 8 2009
SYNOPSIS
RELATIVELY LOW AMPLITUDE FLOW EXPECTED FOR THE FCST
PERIOD...WITH MEAN TROF POSN TO THE W AND RIDGE TO THE E. SOME
TENDENCY TO SPLIT STILL EXPECTED LATER IN THE PERIOD. THE PATTERN WL
KEEP MILD PACIFIC AIR STREAMING ACRS THE RGN...AND RESULT IN ABV
NORMAL TEMPS. TWO MAIN SYSTEMS WL BRING CHCS OF PCPN TO THE AREA.
THE FIRST WL MV ACRS THE RGN EARLY...BUT WITH VERY LIMITED MOISTURE
PCPN LIKELY TO BE SCT AND AMNTS VERY LGT. SECOND WL ARRIVE LATER IN
THE WEEK AND NEXT WEEKEND.
SHORT TERM
TDA/TNGT/MON. TREND ON THE MODELS CONCERNING THE
INCOMING SYSTEM HAS BEEN TO PULL BACK ON PRECIP...AND TO SOME EXTENT
EVEN CLOUDS. HARD TO ARGUE WITH THAT SINCE THAT/S HOW THE LAST
SYSTEM PLAYED OUT...AND 00Z RAOBS OUT TO THE W AND SW WERE VERY DRY.
SO...PUSHED FCST IN THAT DIRECTION. KEPT JUST CHC OF SPRINKLES OVER
N-C WI TDA...AND WENT WITH JUST SPRINKLES OVER ALL BUT E-C WI TNGT.
MODELS ALSO SUGGESTED FRONTAL CLOUD BAND WL BE SHIFTG SEWD AFTER
MIDNIGHT...SO STARTED DECR CLD TREND OVER THE NW PART OF THE FCST
AREA LATE.
SUPPOSE THERE COULD BE SOME SPRINKLES OVER E-C WI EARLY MON...BUT AT
THIS POINT CHC SO MARGINAL WL JUST LEAVE THEM OUT. WENT WITH MORE
SUN OVER THE NW PART OF THE AREA...BUT THE SE COULD STILL SEE CI ON
THE NW EDGE OF FRONTAL CLOUD BAND.
GUID TEMPS FOR TDA QUITE WARM AND 850 MB TEMPS REALLY DON/T FALL OFF
MUCH FM YDA AFTN. BUT WE WL BE GETTING OFF TO A COLDER START...NOT
GET FULL SUN LIKE YDA...AND HAVE A DEVELOPING SELY FLOW. SO ALTHOUGH
THE BIAS CORRECTED MAV GUID HAS BEEN DOING WELL...IT SEEMED TOO
WARM. INSTEAD WENT WITH A MORE ROBUST BLEND OF THE VARIOUS GUID
PRODUCTS...AND LOWERED TEMPS A LITTLE MORE LAKESIDE WHERE WATER
TEMPS ARE ARND 50. USED BLENDS OF GUID FOR TNGT AND MON AS WELL.
THAT RESULTED IN GOING A LITTLE COOLER IN WRN AREAS TNGT...AND A
LITTLE WARMER MOST AREAS MON. THAT FIT WITH HAVING CLDS DECR IN THE
W LATER TNGT...AND FEWER CLDS ON MON THAN PREVIOUSLY ANTICIPATED.
LONG TERM
MON NGT THRU NXT SAT. MEAN FLOW FOR THE FIRST HALF OF
THE WEEK TO BE DICTATED BY AN ERN PACIFIC/WRN CONUS UPR TROF WITH
A SOMEWHAT FLAT DOWNSTREAM UPR RDG OVR THE CNTRL CONUS. THIS PATN
TO KEEP A DRY AND MILD WEATHER REGIME OVR NE WI. A PIECE OF SHRTWV
ENERGY TO EJECT NEWD FROM THE MAIN TROF AND MOV NE TOWARD THE
GREAT LKS LATE NXT WEEK. THIS WOULD APR TO BE THE FIRST
OPPORTUNITY OF SEEING ANY PCPN...BUT TIMING AND EXTENT STILL UP
FOR DEBATE AMONG THE MDLS. MAIN FCST CHALLENGE IN THE SHORT-TERM
WL BE TEMPS AND PCPN QSTNS THE LONG RANGE ISSUE.
INDICATIONS ARE THAT ANY FRONTOGENETICAL FORCED PCPN WL REMAIN SE
OF THE FCST AREA MON NGT...LEAVING AN INFLUX OF DRIER AIR TO
STEADILY OVERSPREAD WI AHD OF AN AREA OF HI PRES SITUATED OVR THE
MIDWEST. LOOK FOR SKIES TO BECOME MOSTLY CLR OVR NRN AND CNTRL WI
WITH E-CNTRL WI SEEING A GRADUAL DECREASE IN CLDS. THIS DECREASE
IN CLDS...COUPLED WITH DIMINISHING WNDS WL ALLOW TEMPS TO DROP OFF
PRETTY WELL. MIN TEMPS WL RANGE FROM AROUND 30 DEGS NORTH TO THE
UPR 30S NEAR LK MI.
THE HI PRES MOVS EAST AND WL BE LOCATED RIGHT OVR THE HEART OF WI
ON TUE...BRINGING PLENTY OF SUNSHINE TO THE RGN. TEMPS WL BE A BIT
COOLER THAN THE PAST COUPLE OF DAYS WITH 8H TEMPS ONLY AROUND +3C.
NEVERTHELESS...LOOK FOR MAX TEMPS TO REACH THE 50 TO 55 DEG RANGE
WHICH WOULD BE 5 TO 10 DEGS ABV NORMAL.
AS THE HI PRES SLOWLY HEADS EAST ACROSS LWR MI TUE NGT...A RETURN
FLOW WL GRADUALLY DVLP OVR WI. LGT SOUTHERLY WNDS WL NOT BE ENUF
TO STOP TEMPS FROM FALLING WITH SKIES STILL MOSTLY CLR. TUE NGT
STILL APRS TO BE THE COOLEST OF THE EXTENDED PERIOD WITH UPR 20S
OVR THE NORTH TO THE MID 30S NEAR THE LAKE. S-SW WNDS FIRMLY IN
PLACE OVR THE RGN ON WED AS THE RELATIVELY FLAT UPR RDG TO BE
SITUATED OVR THE CNTRL CONUS. MDLS DO SHOW A VERY WEAK SHRTWV
TROF/EMBEDDED SHRTWV TO BE MOVG ALONG THE U.S.-CANADIAN BORDER
WHICH MAY INTERACT WITH SOME ISEN LIFT TO GENERATE A BAND OF CLDS
(ESP OVR THE NORTH). ONLY THE ECMWF DVLPS LGT PCPN WITH THESE
FEATURES...HOWEVER DUE TO THE DRY AIRMASS IN PLACE...HAVE KEPT WED
DRY. ONLY CHG TO WED WL BE TO ADD A FEW MORE CLDS TO THE NORTH
WHICH MAY KEEP TEMPS FROM REACHING 50 DEGS.
A MORE PRONOUNCED SHRTWV TROF IS PROGGED TO MOV INTO THE NRN
PLAINS ON THU AND HELP PUSH A CDFNT INTO THE UPR MIDWEST BY 00Z
FRI. EVEN THO THIS SYSTEM WL AID IN THE INCREASE IN BOTH LOW-LVL
MSTR AND ISEN ASCENT...THE AIRMASS IS STILL RELATIVELY DRY AND
FORCING IS RATHER WEAK. PREFER TO ONLY MENTION A SLGT CHC OF LGT
RAIN FOR N-CNTRL WI WHERE STRONGER ISEN LIFT TO BE PRESENT. MORE
CLDS NORTH...LESS CLDS SE WL PROVIDE A WIDER RANGE IN THE TEMPS
WITH UPR 40S NORTH TO MID 50S SE.
CHC OF PCPN BECOME AN ISSUE FOR THE END OF THE WEEK AS THE MDLS
CONT TO STRUGGLE WITH THE STRENGTH OF OF THE SHRTWV TROF MOVG
ACROSS THE UPR MIDWEST/NRN SECTIONS OF THE GREAT LKS. THE GFS
REMAINS THE MOST RAMBUNCTIOUS...THE ECMWF RATHER FEEBLE...WITH THE
CANADIAN SOMEWHERE IN BETWEEN (AND SLOWER). PRELIM INDICATIONS
WOULD SEEM TO POINT TO A CHC OF LGT RAIN ACROSS N-CNTRL WI THE NGT
AND OVR MOST OF THE FCST AREA ON FRI AS THE CDFNT SLOWLY PUSHES
INTO WI. BETTER CHCS FOR PCPN WOULD THEN SAG SOUTH BY SAT AS THE
FNT GRINDS TO A HALT AS IT BECOMES PARALLEL WITH THE MEAN FLOW
ALOFT.
AVIATION
VFR CONDITIONS EXPECTED TDA. MVFR VSBYS WITH FOG
LIKELY MOST AREAS TNGT. AT THIS POINT MOISTURE LOOKS TOO LIMITED
FOR WIDESPREAD IFR CIGS TNGT.
GRB WATCHES/WARNINGS/ADVISORIES
NONE.
SKOWRONSKI/KALLAS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page