5 day has shifted west
Hurricane Frances Discussion Number 24
Statement as of 5:00 PM EDT on August 30, 2004
Reports from a NOAA p-3 hurricane hunter plane indicate that the
central pressure has dropped to 948 mb and there was a flight
level...700 mb...wind of 122 kt just east-southeast of the center.
Based on these data the current intensity is increased to 110 kt.
There is strong upper-level outflow and vertical shear is expected
to remain low. There will probably be some fluctuations in
intensity due to inner core processes...such as the concentric
eyewalls that were observed by the hurricane hunters and also seen
in trmm and SSM/I data. However...additional strengthening is
certainly possible and the official wind speed forecast is probably
conservative.
The wind radii have been adjusted a little based on observations
from the stepped-frequency microwave radiometer...sfmr...on board
the NOAA aircraft.
The hurricane remains on track...275/12. A deep-layer subtropical
ridge is likely to prevail to the north of Frances over the next
several days. Beyond 72 hours...some weakening of this ridge is
indicated by the global models. The bad news for the Bahamas and
Florida Peninsula is that there is no significant mid-latitude
trough in the current model forecasts through 5 days that could
substantially weaken this ridge. The official forecast shows some
slowing and a slight bending of the track toward the northwest
beyond 72 hours...but this forecast has been shifted a little left
in comparison to the previous one. This is in good agreement with
the consensus of the dynamical models.
Once again...it is extremely important not to focus on the exact
track...especially at 96 and 120 hours...because the hurricane is
not a point...especially a hurricane as large as Frances...and
forecasts at these extended time ranges can easily have errors of
several hundred miles.
Forecaster Pasch
forecast positions and Max winds
initial 30/2100z 19.5n 60.0w 110 kt
12hr VT 31/0600z 19.7n 62.1w 115 kt
24hr VT 31/1800z 20.2n 64.8w 115 kt
36hr VT 01/0600z 21.0n 67.4w 115 kt
48hr VT 01/1800z 22.0n 70.0w 115 kt
72hr VT 02/1800z 24.0n 74.0w 120 kt
96hr VT 03/1800z 25.5n 77.0w 120 kt
120hr VT 04/1800z 27.5n 80.0w 120 kt
5pm Frances 125 mph... west shift
Moderator: S2k Moderators
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-
PurdueWx80
- Professional-Met
- Posts: 2720
- Joined: Fri Aug 13, 2004 8:33 pm
- Location: Madison, WI
- Contact:
I think it was a very smart move to shift this thing west. We are getting into the range of a 5-day forecast that includes a potential landfall (well, the cone anyway), and the NHC will only get more accurate. I wouldn't be surprise if it is shifted slightly further west, especially w/o any signfificant midlatitude trough to recurve her. The 18Z Eta still has the edge of the ridge all the way back to the central Gulf, and an extrapolation of the model would show a landfall between Miami and West Palm Beach on Saturday.
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Aquawind
- Category 5
- Posts: 6714
- Age: 62
- Joined: Mon Jun 16, 2003 10:41 pm
- Location: Salisbury, NC
- Contact:
Sorry if this is a repost..Interesting SC call...
This really conflicts with NHC and models data..
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
226 PM EDT MON AUG 30 2004
VALID 12Z THU SEP 02 2004 - 12Z MON SEP 06 2004
FINAL MODEL DISCUSSION...
00Z GFS MEANS INDICATE AMPLIFICATION OF MID LVL FLOW FROM D+3 TO
D+8... WITH THE FCST AT THE END OF THE PERIOD SHOWING A NERN
PAC/AK RIDGE... CNTRL CONUS/SRN CANADA TROF... AND NEW ENG/ERN
CANADA RIDGE. THE ECMWF D+8 SHOWS MUCH FLATTER FLOW ALONG 40-60N
EXCEPT FOR TROFFING FROM GREENLAND SWD IN CONTRAST TO THE GFS MEAN
WHOSE TROF IS MUCH FARTHER EAST. D+8 MEANS FROM ECMWF/NCEP ENS
MEANS RECOMMEND FLATTER FLOW THAT IS CLOSER TO THE ECMWF D+8. OP
RUNS OF THE 06Z/12Z GFS SIDE WITH THE LESS AMPLIFIED PATTERN AS
WELL.
12Z UPDATE...
OVER THE NORTHEAST... THE 12Z GFS/CANADIAN HAVE TRENDED TOWARD
RECENT ECMWF RUNS AND 00Z UKMET WHICH SHOW STG HIGH PRES OVER ERN
CANADA SUPPORTING A REINFORCING PUSH OF COOL AIR INTO NEW ENG
AROUND BY DAY 5 SAT. WHILE FLOW OVER THE ERN PAC/WRN NOAM MAY BE
IN THE PROCESS OF FLATTENING... CNTRL/ERN NOAM PATTERN STILL SEEMS
TO LEAVE ROOM FOR A BACKDOOR FRONT OVER NEW ENG. THUS TRENDED
TOWARD THE 12Z GFS... WHICH IS STILL NOT AS AGGRESSIVE AS ECMWF
RUNS.
WITH HRCN FRANCES... LATEST GFS/GFDL/UKMET RUNS HAVE ALL DISPLAYED
A TREND TO THE LEFT COMPARED TO PRIOR RUNS. THE 12Z CANADIAN IS
EWD OF ITS 00Z RUN WITH A TRACK NOT FAR FROM THE 12Z GFDL AND A
BIT WWD OF THE 06Z GFS. EXTRAPOLATION OF TPC/NHC FCST FROM 1500
UTC ADVISORY BRINGS THE SYSTEM INTO SRN SC BY EARLY NEXT MON.
CONSULT TPC/NHC DISCUSSIONS FOR UPDATED INFO REGARDING FRANCES.
OVER THE WRN/CNTRL CONUS DAYS 5-7... THE 12Z GFS HAS TRENDED
SLIGHTLY WEAKER THAN THE 06Z GFS WITH THE WRN CONUS RIDGE BUT
REMAINS SIMIALAR TO THE 06Z RUN WITH THE ENERGY THAT CUTS OFF OVER
THE CNTRL PLAINS. THE 00Z ECMWF IS A BIT N OF 06Z/12Z GFS RUNS
WITH THIS ENERGY. THERE IS STILL NOT MUCH SUPPORT FOR THE STG SFC
HIGH OVER THE HIGH PLAINS FCST BY THE GFS... SO WILL NOT CHANGE
PRELIM FCST HERE.
UPDATED PRELIM DISCUSSION...
BY LATE IN THE PERIOD THE 06Z GFS AND GFDL TREND A FRACTION TO THE
LEFT... AND THE 06Z GFS A TAD FASTER... WITH HRCN FRANCES. DID
NOT CHANGE EARLY PRELIM DAYS 6-7 SUN-MON POSNS EXTRAPOLATED FROM
TPC/NHC TRACK THRU DAY 5 BASED ON 0900 UTC ADVISORY... PENDING
1500 UTC ADVISORY AND 1600 UTC MEDR COORDINATION FOR DAYS 6-7.
OTHERWISE THE SIGNIFICANT FCST PROBLEM CONTINUES TO BE THE FLOW
OVER THE ERN PAC INTO CNTRL NOAM. ECMWF ENSEMBLE MEMBERS AGREE
WITH THE MAJORITY OF NCEP MEMBERS THAT THE 00Z OP GFS IS TOO
AMPLIFIED WITH THE CNTRL CONUS TROF DAYS 5-7 SAT-MON. WHILE THE
06Z GFS HAS TRENDED FAVORABLY TOWARD HIGHER HGTS IN THIS TIME
FRAME... IT MAY BE OVERDOING WRN CONUS RIDGING WHICH IN TURN
PUSHES CNTRL PLAINS/MS VLY ENERGY TOO FAR S. THE LATTER RESULTS
IN MUCH STRONGER SRN PLAINS HIGH PRES THAN ANY OTHER OP/ENS
GUIDANCE RECOMMENDS. CONSIDERATION OF EXTENDED RANGE MEAN FCSTS
FROM THE LAST DAY OR SO AND HIGHER THAN AVERAGE UNCERTAINTY... THE
NCEP ENS MEAN LOOKS LIKE THE BEST OPTION OVER THE CNTRL/WRN CONUS.
TEMP-WISE OVER THE NRN STATES... SUCH A SOLN OFFERS A COMPROMISE
BETWEEN THE VERY COOL 00Z GFS AND MUCH WARMER 06Z RUN. TEMP/POP
GUIDANCE IS STILL BEING PREPARED... BUT A QUICK GLANCE AT SOME 00Z
MOS GUIDANCE INDICATES THAT CLIMO INFLUENCES MAY ALREADY BE AIDING
THE TREND TOWARD THE PREFERRED COMPROMISE SOLN BY SUN-MON.
EARLY PRELIM MODEL DISCUSSION...
THE MODELS ARE IN REASONABLY GOOD AGREEMENT IN THE MEDIUM RANGE.
CHANGES TO THE EARLIER HPC PROGS WERE MOSTLY SMALL...WITH THE
BIGGEST EXCEPTION BEING WITH THE TRACK OF HRCN FRANCES.
THE 00Z GFS HAS MADE A BIG TURN TO THE N COMPARED TO ITS PREVIOUS
RUNS...BYPASSING FL AND LEAVING THE SYSTEM IN THE ATL THRU THE
MEDR. THE 29/12Z AND 30/00Z NOGAPS AND 00Z GFDL ARE ALSO TURNING
THE SYS NWD IN THE BAHAMAS AND SENDING THE SYS UP THE E COAST.
THE 00Z CAN GLOB TAKES FRANCES THRU THE FL STRAITS INTO THE GOMEX
WHILE THE 29/12Z ECMWF MOVE FRANCES NWWD FROM S FL INTO THE TBW
AREA BY DAY 6/SUN. THE ECMWF AND GFS HAVE BOTH TRENDED TOWARD
BUILDING A STRONGER UPR TROF OVER THE NORTHEAST EARLY IN THE MEDR
PD AND MOVE THE NEXT TROF INTO THE CNTRL CONUS MORE QUICKLY THAN
THEIR EARLIER RUNS. THIS SHUD HELP BREAK DOWN THE RIDGE TO THE N
AND W OF THE SYS...ALLOWING FOR A GREATER POSSIBILITY OF A NWD
TURN...EVEN THOUGH THE ECMWF STILL TAKES THE SYS INTO THE GOMEX. THE 00Z NCEP ENS MEMBS ARE SPLIT BY DAY 6/SUN...WITH HALF OF THE
MEMBS MAKING THE NWD TURN AND KEEPING THE SYS IN THE ATL AND HALF
PUSHING THE SYS INTO THE GOMEX. THIS IS A CHANGE FROM THE RUN
LAST NIGHT WHEN MORE OF THE MEMBS WERE BEING CARRIED WWD TOWARD
THE GOMEX. THE OVERALL TREND IN THE MODELS DOES SEEM TO BE TOWARD
THE RIGHT WITH THE FORECAST TRACK IN THE MEDIUM RANGE...WEAKENING
THE H5 RIDGE TO THE N OF THE SYS THERFORE... EXTRAPOLATED THE NHC
FORECAST WHICH LEANED HEAVILY ON THE 00Z GFS WHICH MAKES THE TURN
IN THE BAHAMAS. SEE THE LATEST NHC BULLETINS FOR THE OFFICIAL
FORECAST FOR FRANCES.
ELSEWHERE OVER THE CONUS...AN UPR TROF IS XPCTD TO SLOWLY PASS EWD
FROM THE NWRN CONUS ON DAY 3/THURS INTO THE CNTRL CONUS. MOST OF
THE RUNS TONIGHT...SANS THE CAN GLOB AND 29/12Z NOGAPS...HAVE
ABANDONED THE IDEA SHARED BY MOST OF THE MODELS YESTERDAY WHICH
HELD MORE ENERGY IN THE BASE OF THE UPR TROF...SLOWING IT
DOWN/MAKING IT MORE POS TILTED. THE TREND IN THE GFS IS TOWARD A
SLIGHTLY MORE EWD UPR TROF AXIS...WHICH HELPS TO ERODE THE UPR
RIDGE TO THE N OF HRCN FRANCES. THE SHORT TERM TRENDS IN THE NCEP
ENS MEAN AND ECMWF HAVE ALSO TRENDED SLIGHTLY MORE ELY WITH THE
TROF AXIS IN THE CNTRL CONUS BY MID PD.
THE MODELS ARE IN REASONABLE AGREEMENT WITH THE TIMING OF THE
PATTERN...WITH THE ECMWF A BIT MORE ON THE SLOW SIDE...THRU DAY
5/SAT. MORE VARIABILITY IN THE SOLNS OVER THE CONUS COMES INTO
PLAY AS THE ENERGY OVER THE GULF OF AK ON DAY 5/SAT DROPS INTO THE
BACKSIDE OF THE BROAD UPR TROF. THE 00Z NCEP MEAN SHOWS A 150M
SPREAD WITH THE RIDGE JUST AHEAD OF THIS TROF. THE ECMWF HAS
TRENDED MORE TOWARD THE OP GFS AND NCEP MEAN...MOVING TOWARD A
FLATTER PATTERN ON THE BACKSIDE OF THE UPR TROF ATTM. THE 00Z GFS
DROPS THE GULF OF AK H5 TROF SEWD...AMPLIFYING THE BROAD TROF OVER
THE CNTRL CONUS MORE VIGOROUSLY THAN THE ECMWF OR NCEP ENS MEAN.
THE UKMET AND CAN GLOB...ALONG WITH THE ECMWF AND NCEP MEAN...SEEM
TO PREFER A BROADER H5 TROF OVER THE...WITH THE GULF OF AK ENERGY
DROPPING INTO THE TROF FROM A MORE WLY PSN THAN THE 00Z GFS.
THEREFORE...ADJUSTED THE SOLN MORE TOWARD THE 00Z NCEP ENS MEAN ON
DAYS 6/SUN AND 7/MON.
THE GFS...UKMET...CAN GLOB...AND ECMWF AGREE ON DEVELOPING A
POTENTIAL TROP CYC IN THE E PAC WHICH ORIGINATES NEAR 13N 103W.
THE CAN GLOB IS THE ONLY ONE OF THESE MODELS NOT TO KEEP THE SYS
CLOSE TO THE BAJA...PREFERRING TO SEND IT ON A MORE WLY TRACK.
THE MANUAL PROGS REFLECT THE ECMWF/GFS WHICH ARE IN GOOD
AGREEMENT. THIS TRACK IS A BIT SLOWER THAN THE PREVIOUS PROGS
LIFTING THE SYS NWD.
REGIONAL HIGHLIGHTS...
...ALASKA...
OP/ENS GUIDANCE ARGUES A STRONG CASE AGAINST BRINGING A DAYS 6-7
SUN-MON SYSTEM INTO SRN AK AS QUICKLY AS THE 00Z OP GFS... IF IT
REACHES THAT FAR N AT ALL. EARLIER IN THE PERIOD... THERE IS
REASONABLE AGREEMENT WITH A FRONTAL SYSTEM PUSHING THRU SERN AREAS
WITH A DRYING/COOLING TREND IMMEDATELY BEHIND THIS SYSTEM. OVER
NRN/WRN LOCATIONS... EXPECT PERIODS OF LGT PCPN AS ENERGY ROTATES
AROUND A CLOSED LOW NE OF THE STATE.
...WRN CONUS/NAME AREA...
SFC HIGH BUILDING INTO THE GRTBASIN AND NRN INTERMTN WEST SHOULD
PROMOTE OFFSHORE FLOW AND ABOVE NORMAL DAYTIME TEMPS OVER CA
DURING THE LATTER HALF OF THE WEEK. SFC HIGH SHOULD WEAKEN DURING
THE WEEKEND... BUT WITH MID LVL HGTS RISING IN THE WAKE OF THE
TROF INITIALLY OVER THE WEST... EXPECT TEMPS TO BE ON THE WARM
SIDE OVER AN INCREASING PORTION OF THE WEST LATE WEEKEND INTO
EARLY NEXT WEEK. PCPN CHANCES OVER THE EXTREME SW ARE CONTINGENT
UPON ERN PAC TROPICAL ACTIVITY... OTHERWISE ONLY PCPN SHOULD BE
LGT/SCT OVER FAVORED TERRAIN EXTREME NORTH.
MODELS ARE SLOWER TO LIFT THE POTENTIAL T.C. IN THE E PAC NWD
ALONG THE BAJA COMPARED TO PREVIOUS DAYS. THE GFS SHED SOME H5
VORT ENERGY NEWD OFF THE SYS...GENERATING AN AREA OF PCPN WHICH
LIFTS NWD THRU THE SRN TO THE CNTRL TIER 1 REGION BY THE END OF
THE PD. THE 00Z GFS IS SIG WETTER THAN THE 12Z RUN HERE. GIVEN
THE TREND FOR A SLOWER SYS...WOULD NOT BANK ON THE HEAVY PCPN OF
THE 00Z GFS. HOWEVER...ASSUMING THE ECMWF/GFS TRACK PANS
OUT...XPCT A SURGE OF MSTR NWD THRU THE GULF OF CA THRU THE MEDR
PD.
...CNTRL/ERN CONUS...
COLD FRONT EXTENDING FROM THE NRN PLAINS SWWD AS OF EARLY THU
SHOULD PUSH EWD THRU THE PERIOD... LIKELY DECELERATING OVER THE
GRTLKS TO S-CNTRL PLAINS BY SUN-MON AS IT RUNS INTO A STG RIDGE
SFC/ALOFT. EXPECT THIS FRONT TO SUPPORT A BAND OF MDT TO LOCALLY
HVY RNFL AS IT PROGRESSES FROM THE NRN PLAINS TO GRTLKS/S-CNTRL
PLAINS DURING THE PERIOD.
BEHIND THE FRONT... PREFER A SOLN CLOSE TO THE NCEP ENS MEAN
LATTER HALF OF THE PERIOD WITH A LESS AMPLIFIED MID LVL TROF THAN
THE 00Z GFS. THIS WOULD LEAD TO WARMER TEMPS THAN SUGGESTED BY A
LITERAL INTERPRETATION OF THE 00Z GFS BY DAYS 5-7. HOWEVER IT
APPEARS CLIMO INFLUENCES HAVE HELPED TO MODERATE 00Z MOS TEMPS
TOWARD THE DESIRED ENS MEAN IDEA.
LATEST GUIDANCE SHOWS A STRONGER CONSENSUS TOWARD AT LEAST NRN NEW
ENG SEEING A REINFORCING PUSH OF COOL AIR FROM ERN CANADA FRI
NIGHT OR SAT... IN CONTRAST TO EARLIER GFS RUNS WHICH KEPT MORE OF
THE REGION UNDER WARM ADVECTION.
REGARDING HRCN FRANCES... MANUAL FCST REFLECTS EXTRAPOLATION OF
TPC/NHC TRACK FROM 1500 UTC ADVISORY. WITH THE SYSTEM FCST TO
REACH THE SE COAST BY THE END OF THE PERIOD... DAYTIME MOS TEMPS
IN ITS VICINITY APPEAR TOO WARM SO THEY WERE ADJUSTED DOWNWARD.
CONSULT TPC/NHC DISCUSSIONS FOR THE LATEST INFO ON FRANCES.
RAUSCH/CLARK
GRAPHICS AVAILABLE AT http://WWW.HPC.NCEP.NOAA.GOV
This really conflicts with NHC and models data..
EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
226 PM EDT MON AUG 30 2004
VALID 12Z THU SEP 02 2004 - 12Z MON SEP 06 2004
FINAL MODEL DISCUSSION...
00Z GFS MEANS INDICATE AMPLIFICATION OF MID LVL FLOW FROM D+3 TO
D+8... WITH THE FCST AT THE END OF THE PERIOD SHOWING A NERN
PAC/AK RIDGE... CNTRL CONUS/SRN CANADA TROF... AND NEW ENG/ERN
CANADA RIDGE. THE ECMWF D+8 SHOWS MUCH FLATTER FLOW ALONG 40-60N
EXCEPT FOR TROFFING FROM GREENLAND SWD IN CONTRAST TO THE GFS MEAN
WHOSE TROF IS MUCH FARTHER EAST. D+8 MEANS FROM ECMWF/NCEP ENS
MEANS RECOMMEND FLATTER FLOW THAT IS CLOSER TO THE ECMWF D+8. OP
RUNS OF THE 06Z/12Z GFS SIDE WITH THE LESS AMPLIFIED PATTERN AS
WELL.
12Z UPDATE...
OVER THE NORTHEAST... THE 12Z GFS/CANADIAN HAVE TRENDED TOWARD
RECENT ECMWF RUNS AND 00Z UKMET WHICH SHOW STG HIGH PRES OVER ERN
CANADA SUPPORTING A REINFORCING PUSH OF COOL AIR INTO NEW ENG
AROUND BY DAY 5 SAT. WHILE FLOW OVER THE ERN PAC/WRN NOAM MAY BE
IN THE PROCESS OF FLATTENING... CNTRL/ERN NOAM PATTERN STILL SEEMS
TO LEAVE ROOM FOR A BACKDOOR FRONT OVER NEW ENG. THUS TRENDED
TOWARD THE 12Z GFS... WHICH IS STILL NOT AS AGGRESSIVE AS ECMWF
RUNS.
WITH HRCN FRANCES... LATEST GFS/GFDL/UKMET RUNS HAVE ALL DISPLAYED
A TREND TO THE LEFT COMPARED TO PRIOR RUNS. THE 12Z CANADIAN IS
EWD OF ITS 00Z RUN WITH A TRACK NOT FAR FROM THE 12Z GFDL AND A
BIT WWD OF THE 06Z GFS. EXTRAPOLATION OF TPC/NHC FCST FROM 1500
UTC ADVISORY BRINGS THE SYSTEM INTO SRN SC BY EARLY NEXT MON.
CONSULT TPC/NHC DISCUSSIONS FOR UPDATED INFO REGARDING FRANCES.
OVER THE WRN/CNTRL CONUS DAYS 5-7... THE 12Z GFS HAS TRENDED
SLIGHTLY WEAKER THAN THE 06Z GFS WITH THE WRN CONUS RIDGE BUT
REMAINS SIMIALAR TO THE 06Z RUN WITH THE ENERGY THAT CUTS OFF OVER
THE CNTRL PLAINS. THE 00Z ECMWF IS A BIT N OF 06Z/12Z GFS RUNS
WITH THIS ENERGY. THERE IS STILL NOT MUCH SUPPORT FOR THE STG SFC
HIGH OVER THE HIGH PLAINS FCST BY THE GFS... SO WILL NOT CHANGE
PRELIM FCST HERE.
UPDATED PRELIM DISCUSSION...
BY LATE IN THE PERIOD THE 06Z GFS AND GFDL TREND A FRACTION TO THE
LEFT... AND THE 06Z GFS A TAD FASTER... WITH HRCN FRANCES. DID
NOT CHANGE EARLY PRELIM DAYS 6-7 SUN-MON POSNS EXTRAPOLATED FROM
TPC/NHC TRACK THRU DAY 5 BASED ON 0900 UTC ADVISORY... PENDING
1500 UTC ADVISORY AND 1600 UTC MEDR COORDINATION FOR DAYS 6-7.
OTHERWISE THE SIGNIFICANT FCST PROBLEM CONTINUES TO BE THE FLOW
OVER THE ERN PAC INTO CNTRL NOAM. ECMWF ENSEMBLE MEMBERS AGREE
WITH THE MAJORITY OF NCEP MEMBERS THAT THE 00Z OP GFS IS TOO
AMPLIFIED WITH THE CNTRL CONUS TROF DAYS 5-7 SAT-MON. WHILE THE
06Z GFS HAS TRENDED FAVORABLY TOWARD HIGHER HGTS IN THIS TIME
FRAME... IT MAY BE OVERDOING WRN CONUS RIDGING WHICH IN TURN
PUSHES CNTRL PLAINS/MS VLY ENERGY TOO FAR S. THE LATTER RESULTS
IN MUCH STRONGER SRN PLAINS HIGH PRES THAN ANY OTHER OP/ENS
GUIDANCE RECOMMENDS. CONSIDERATION OF EXTENDED RANGE MEAN FCSTS
FROM THE LAST DAY OR SO AND HIGHER THAN AVERAGE UNCERTAINTY... THE
NCEP ENS MEAN LOOKS LIKE THE BEST OPTION OVER THE CNTRL/WRN CONUS.
TEMP-WISE OVER THE NRN STATES... SUCH A SOLN OFFERS A COMPROMISE
BETWEEN THE VERY COOL 00Z GFS AND MUCH WARMER 06Z RUN. TEMP/POP
GUIDANCE IS STILL BEING PREPARED... BUT A QUICK GLANCE AT SOME 00Z
MOS GUIDANCE INDICATES THAT CLIMO INFLUENCES MAY ALREADY BE AIDING
THE TREND TOWARD THE PREFERRED COMPROMISE SOLN BY SUN-MON.
EARLY PRELIM MODEL DISCUSSION...
THE MODELS ARE IN REASONABLY GOOD AGREEMENT IN THE MEDIUM RANGE.
CHANGES TO THE EARLIER HPC PROGS WERE MOSTLY SMALL...WITH THE
BIGGEST EXCEPTION BEING WITH THE TRACK OF HRCN FRANCES.
THE 00Z GFS HAS MADE A BIG TURN TO THE N COMPARED TO ITS PREVIOUS
RUNS...BYPASSING FL AND LEAVING THE SYSTEM IN THE ATL THRU THE
MEDR. THE 29/12Z AND 30/00Z NOGAPS AND 00Z GFDL ARE ALSO TURNING
THE SYS NWD IN THE BAHAMAS AND SENDING THE SYS UP THE E COAST.
THE 00Z CAN GLOB TAKES FRANCES THRU THE FL STRAITS INTO THE GOMEX
WHILE THE 29/12Z ECMWF MOVE FRANCES NWWD FROM S FL INTO THE TBW
AREA BY DAY 6/SUN. THE ECMWF AND GFS HAVE BOTH TRENDED TOWARD
BUILDING A STRONGER UPR TROF OVER THE NORTHEAST EARLY IN THE MEDR
PD AND MOVE THE NEXT TROF INTO THE CNTRL CONUS MORE QUICKLY THAN
THEIR EARLIER RUNS. THIS SHUD HELP BREAK DOWN THE RIDGE TO THE N
AND W OF THE SYS...ALLOWING FOR A GREATER POSSIBILITY OF A NWD
TURN...EVEN THOUGH THE ECMWF STILL TAKES THE SYS INTO THE GOMEX. THE 00Z NCEP ENS MEMBS ARE SPLIT BY DAY 6/SUN...WITH HALF OF THE
MEMBS MAKING THE NWD TURN AND KEEPING THE SYS IN THE ATL AND HALF
PUSHING THE SYS INTO THE GOMEX. THIS IS A CHANGE FROM THE RUN
LAST NIGHT WHEN MORE OF THE MEMBS WERE BEING CARRIED WWD TOWARD
THE GOMEX. THE OVERALL TREND IN THE MODELS DOES SEEM TO BE TOWARD
THE RIGHT WITH THE FORECAST TRACK IN THE MEDIUM RANGE...WEAKENING
THE H5 RIDGE TO THE N OF THE SYS THERFORE... EXTRAPOLATED THE NHC
FORECAST WHICH LEANED HEAVILY ON THE 00Z GFS WHICH MAKES THE TURN
IN THE BAHAMAS. SEE THE LATEST NHC BULLETINS FOR THE OFFICIAL
FORECAST FOR FRANCES.
ELSEWHERE OVER THE CONUS...AN UPR TROF IS XPCTD TO SLOWLY PASS EWD
FROM THE NWRN CONUS ON DAY 3/THURS INTO THE CNTRL CONUS. MOST OF
THE RUNS TONIGHT...SANS THE CAN GLOB AND 29/12Z NOGAPS...HAVE
ABANDONED THE IDEA SHARED BY MOST OF THE MODELS YESTERDAY WHICH
HELD MORE ENERGY IN THE BASE OF THE UPR TROF...SLOWING IT
DOWN/MAKING IT MORE POS TILTED. THE TREND IN THE GFS IS TOWARD A
SLIGHTLY MORE EWD UPR TROF AXIS...WHICH HELPS TO ERODE THE UPR
RIDGE TO THE N OF HRCN FRANCES. THE SHORT TERM TRENDS IN THE NCEP
ENS MEAN AND ECMWF HAVE ALSO TRENDED SLIGHTLY MORE ELY WITH THE
TROF AXIS IN THE CNTRL CONUS BY MID PD.
THE MODELS ARE IN REASONABLE AGREEMENT WITH THE TIMING OF THE
PATTERN...WITH THE ECMWF A BIT MORE ON THE SLOW SIDE...THRU DAY
5/SAT. MORE VARIABILITY IN THE SOLNS OVER THE CONUS COMES INTO
PLAY AS THE ENERGY OVER THE GULF OF AK ON DAY 5/SAT DROPS INTO THE
BACKSIDE OF THE BROAD UPR TROF. THE 00Z NCEP MEAN SHOWS A 150M
SPREAD WITH THE RIDGE JUST AHEAD OF THIS TROF. THE ECMWF HAS
TRENDED MORE TOWARD THE OP GFS AND NCEP MEAN...MOVING TOWARD A
FLATTER PATTERN ON THE BACKSIDE OF THE UPR TROF ATTM. THE 00Z GFS
DROPS THE GULF OF AK H5 TROF SEWD...AMPLIFYING THE BROAD TROF OVER
THE CNTRL CONUS MORE VIGOROUSLY THAN THE ECMWF OR NCEP ENS MEAN.
THE UKMET AND CAN GLOB...ALONG WITH THE ECMWF AND NCEP MEAN...SEEM
TO PREFER A BROADER H5 TROF OVER THE...WITH THE GULF OF AK ENERGY
DROPPING INTO THE TROF FROM A MORE WLY PSN THAN THE 00Z GFS.
THEREFORE...ADJUSTED THE SOLN MORE TOWARD THE 00Z NCEP ENS MEAN ON
DAYS 6/SUN AND 7/MON.
THE GFS...UKMET...CAN GLOB...AND ECMWF AGREE ON DEVELOPING A
POTENTIAL TROP CYC IN THE E PAC WHICH ORIGINATES NEAR 13N 103W.
THE CAN GLOB IS THE ONLY ONE OF THESE MODELS NOT TO KEEP THE SYS
CLOSE TO THE BAJA...PREFERRING TO SEND IT ON A MORE WLY TRACK.
THE MANUAL PROGS REFLECT THE ECMWF/GFS WHICH ARE IN GOOD
AGREEMENT. THIS TRACK IS A BIT SLOWER THAN THE PREVIOUS PROGS
LIFTING THE SYS NWD.
REGIONAL HIGHLIGHTS...
...ALASKA...
OP/ENS GUIDANCE ARGUES A STRONG CASE AGAINST BRINGING A DAYS 6-7
SUN-MON SYSTEM INTO SRN AK AS QUICKLY AS THE 00Z OP GFS... IF IT
REACHES THAT FAR N AT ALL. EARLIER IN THE PERIOD... THERE IS
REASONABLE AGREEMENT WITH A FRONTAL SYSTEM PUSHING THRU SERN AREAS
WITH A DRYING/COOLING TREND IMMEDATELY BEHIND THIS SYSTEM. OVER
NRN/WRN LOCATIONS... EXPECT PERIODS OF LGT PCPN AS ENERGY ROTATES
AROUND A CLOSED LOW NE OF THE STATE.
...WRN CONUS/NAME AREA...
SFC HIGH BUILDING INTO THE GRTBASIN AND NRN INTERMTN WEST SHOULD
PROMOTE OFFSHORE FLOW AND ABOVE NORMAL DAYTIME TEMPS OVER CA
DURING THE LATTER HALF OF THE WEEK. SFC HIGH SHOULD WEAKEN DURING
THE WEEKEND... BUT WITH MID LVL HGTS RISING IN THE WAKE OF THE
TROF INITIALLY OVER THE WEST... EXPECT TEMPS TO BE ON THE WARM
SIDE OVER AN INCREASING PORTION OF THE WEST LATE WEEKEND INTO
EARLY NEXT WEEK. PCPN CHANCES OVER THE EXTREME SW ARE CONTINGENT
UPON ERN PAC TROPICAL ACTIVITY... OTHERWISE ONLY PCPN SHOULD BE
LGT/SCT OVER FAVORED TERRAIN EXTREME NORTH.
MODELS ARE SLOWER TO LIFT THE POTENTIAL T.C. IN THE E PAC NWD
ALONG THE BAJA COMPARED TO PREVIOUS DAYS. THE GFS SHED SOME H5
VORT ENERGY NEWD OFF THE SYS...GENERATING AN AREA OF PCPN WHICH
LIFTS NWD THRU THE SRN TO THE CNTRL TIER 1 REGION BY THE END OF
THE PD. THE 00Z GFS IS SIG WETTER THAN THE 12Z RUN HERE. GIVEN
THE TREND FOR A SLOWER SYS...WOULD NOT BANK ON THE HEAVY PCPN OF
THE 00Z GFS. HOWEVER...ASSUMING THE ECMWF/GFS TRACK PANS
OUT...XPCT A SURGE OF MSTR NWD THRU THE GULF OF CA THRU THE MEDR
PD.
...CNTRL/ERN CONUS...
COLD FRONT EXTENDING FROM THE NRN PLAINS SWWD AS OF EARLY THU
SHOULD PUSH EWD THRU THE PERIOD... LIKELY DECELERATING OVER THE
GRTLKS TO S-CNTRL PLAINS BY SUN-MON AS IT RUNS INTO A STG RIDGE
SFC/ALOFT. EXPECT THIS FRONT TO SUPPORT A BAND OF MDT TO LOCALLY
HVY RNFL AS IT PROGRESSES FROM THE NRN PLAINS TO GRTLKS/S-CNTRL
PLAINS DURING THE PERIOD.
BEHIND THE FRONT... PREFER A SOLN CLOSE TO THE NCEP ENS MEAN
LATTER HALF OF THE PERIOD WITH A LESS AMPLIFIED MID LVL TROF THAN
THE 00Z GFS. THIS WOULD LEAD TO WARMER TEMPS THAN SUGGESTED BY A
LITERAL INTERPRETATION OF THE 00Z GFS BY DAYS 5-7. HOWEVER IT
APPEARS CLIMO INFLUENCES HAVE HELPED TO MODERATE 00Z MOS TEMPS
TOWARD THE DESIRED ENS MEAN IDEA.
LATEST GUIDANCE SHOWS A STRONGER CONSENSUS TOWARD AT LEAST NRN NEW
ENG SEEING A REINFORCING PUSH OF COOL AIR FROM ERN CANADA FRI
NIGHT OR SAT... IN CONTRAST TO EARLIER GFS RUNS WHICH KEPT MORE OF
THE REGION UNDER WARM ADVECTION.
REGARDING HRCN FRANCES... MANUAL FCST REFLECTS EXTRAPOLATION OF
TPC/NHC TRACK FROM 1500 UTC ADVISORY. WITH THE SYSTEM FCST TO
REACH THE SE COAST BY THE END OF THE PERIOD... DAYTIME MOS TEMPS
IN ITS VICINITY APPEAR TOO WARM SO THEY WERE ADJUSTED DOWNWARD.
CONSULT TPC/NHC DISCUSSIONS FOR THE LATEST INFO ON FRANCES.
RAUSCH/CLARK
GRAPHICS AVAILABLE AT http://WWW.HPC.NCEP.NOAA.GOV
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