18z GFS and 12z EURO but is it right?

[Stormsfury]

Nope...

(This will be rather brief as I'm under the weather with a stomach flu)

The 18z GFS crushes the s/w in the southern stream overdoing the PJ (not the PV, sorry). Tonight's EURO progging a MASSIVE warmup in the Plains by Day 7 ...

Yes the flow is progressive ... however, the 500mb heights do NOT match up with the SFC features at all ...

We're looking at a time of PNA ridging, however, there is NO 50/50 low to lock things down ...

But what bothers me about BOTH the 18z GFS and 12z EURO are their known biases clearly showing up here, with the GFS crushing/shearing s/w(overdoing) the PJ, and the ECMWF's known mishandling of southern stream s/w energy. I am uncertain and don't know at this time what the consequences, but the 12z GFS ENS members (a good degree of them) still support a major storm about 10 days from now. Although an old run now, the 00z CMC ensemble members are hinting at the potential still existing ...

And Im not writing off a little winter weather event just yet (with model support from the 12z GFS/Canadian/UKMET sorta on board) ... yes, this is a very fast flow still but IMHO, I don't see the cold air being scoured out as easily as the models indicate at this time.

If anything, model tendencies lately have been on the cold train for 24-36 hours, followed by a warm train for 24-36 hours, and then back again.

SF

[therock1811]

Sorry to hear bout that stomach flu...you take care of yourself...as for the GFS, let's hope for once it doesn't verify...same for that EURO...

[cycloneye]

Hey Mike get rid of that flu as soon as possible.

[Stormsfury]

The stomach flu came on today and it's been rather ugly to stay the least ... Becky has had it for about 4 days now, and she's still having some issues as well with it, so we decided not to go out tonight, and postpone until Next Saturday. Since she's not too far from me, I may stop over there later if we feel up to it.

Anyways, the 12z GFS (12z ops runs) still makes a little more sense with the potential of the SECS/MECS in the MR. And the potential of a wintry weather mixture in the Carolinas ... something, to my surprise that was mentioned in the AFD's across South Carolina, including Charleston's this afternoon. But the ensembles continue to support a more substantial development after the little southern stream s/w.

SF

[Stormsfury]

Snippets of CHS and CAE AFD's this afternoon.

.LONG TERM...CDFNT WL APPROACH THE AREA ON MON THEN PASS OFFSHORE
MON NGT. DESPITE PWATS OVR 1 INCH...SHEARED VORTICITY ALOFT AND LTL
IN THE WAY OF FORCING ALOFT CONTS TO FAVOR LOWISH CHANCE POPS ALONG
AND JUST AHEAD OF THE FNT. THE FNT SHOULD CLR THE COAST AFT MIDNGT
WITH CONSIDERABLY COLDER AND DRIER CONDS PREVAILING THROUGH THU. A
HARD FREEZE IS ON TAP FOR AREA WED NGT AS LOWS ARE FCST TO PLUMMET
WELL INTO THE 20S EVEN ALONG THE BEACHES. WK COASTAL TROFG PSBL BY
WEEKS END AS BRIEF HYBRID WEDGE DVLPS OVR INLAND AREAS. A WK GULF
SYSTEM IS FCST TO MOVE INTO THE SW ATLC AND MERGE WITH THE COASTAL
TROF FRI-SAT. BEST CHANCES FOR PRECIP WL BE CONFINED TO COASTAL
AREAS. THE OPERATIONAL GFS IS MUCH MORE AGGRESSIVE IN THE DVLPMNT OF
THIS SYSTEM AND ACTUALLY BRINGS SOME MARGINALLY FAVORABLE PARTIAL
THICKNESSES FOR WINTER PCPN INTO THE NRN ZONES BY SAT AFTN AS THE
SYSTEM DEPARTS. FEW OF THE ENSEMBLES MEMBERS SUPPORT SUCH A STRONG
SYSTEM ATTM SO WL DISCOUNT THE OPERATIONAL LOW RESOLUTION GFS ATTM.
WL CONT TO MONITOR. THANKS JAX/ILM/HPC FOR THE COLLABORATION THIS
AFTN.

.LONG TERM...
FRONT WILL BE SOUTH AND EAST OF THE AREA BY TUESDAY. DRY AND COLD
WEATHER BOTH TUESDAY AND WEDNESDAY AS HIGH PRESSURE BUILDS IN. MAX
TEMPS BELOW NORMAL IN THE UPPER 40S TO LOWER 50S. LOWS IN THE 20S.
MUCH UNCERTAINLY EXIST FOR THE WEEK'S END. GFS/ECWMF SHOWING COLD
AIR PLACE WITH LOW PRESSURE OVER THE GULF OF MEX FRIDAY MOVING
ACROSS FLORIDA AND OFF THE SC/GA COAST SATURDAY. THIS COULD SPREAD
WINTRY WX INTO THE AREA FRIDAY DEPENDING ON HOW MUCH MOISTURE THE
SYSTEM CAN PICK UP. FOR NOW WILL GO WITH A CHANCE OF SHOWERS FOR
FRIDAY. DRY WX SATURDAY WITH LOW PULLING NORTHEAST.

[Guest]

Sounds reasonable to me seeing how everything has now missed me in everyother direction. LOL

[Stormsfury]

Day 10 ECMWF 3 day average ... significant threat still there.

EURO 3 day average Days 8-10

[FLguy]

Day 10 ECMWF 3 day average ... significant threat still there.

EURO 3 day average Days 8-10

Yes there is still a threat for a SECS/MECS in the 13-15 time frame as s/w energy undercuts the PNA ridge. DO NOT pay any attention to the operational GFS run from 18z this evening...it is utter BS. the model puts too much emphasis on PJ.

[Stormsfury]

Another case, of why the GFS maybe should only be run at 00z and 12z.

SF

[FLguy]

Another case, of why the GFS maybe should only be run at 00z and 12z.

SF

If the model wanst good for poops and giggles once in awhile it would be for the most part a worthless waste of money to run.

[Stormsfury]

LOL

[FLguy]

but on a more serious note...as many of you can recall...when NCEP decided to combine the MRF and AVN model output in 2002 into one (which you know as the GFS)...these biases were SUPPOSED to have been worked out. though we keep noticing the same thing with the model now.

The the GFS has several biases. the most notable of course (since the operational AVN/MRF output has been combined) is the GFS issue with overdoing the strength and amplitude of the pattern across North America.

the operationally significant implication of the models biases relate to the fact that the model is more likely to overestimate the amount of cold air present... it can also throw off the models precipitation type forecasting Algorithm causing the model to be more aggressive when predicting snowfall. in addition the model is MORE likely to forecast tempereatures significantly colder than most other models in the long range.

most of these biases are seen the clearest BEYOND 84 hours. furthermore the effect of the bias to supress the pattern can lead to the model forecasing many coastal low pressure areas to exit the east coast too far south and east against the overall consensus.

The cause of this bias in the models output is unclear. In the warm season the model has convective feedback problems relating to the models convective paramaterization scheme. This primarly effects the models ability to correctly forecast convective rainfall.

The GFS ensembes are MUCH more reliable though not w/o fault. The ensembles also like to keep the trough in the eastern part of the country in the long range and seem to have a problem with amplified patterns.

the strength of systems as forecasted by the GFS ensembles can seem weaker than what the operational run or the individual members may indicate however since the ensembls are a mean of the outputof the individual members (it diminishes the amplification in the pattern in mass fields) the strength of the system can at times be weaker than the operational model...of course depending on how strong the system is progged by the operational run. also since the EPS (ensemble prediction System) is a compilation of several model solutions...it is LESS likely to accurately depict extremes...especially when there is strong disagreement between the members (normally occuring in the longer range).