00Z model discussion

[mitchnick]

Does it matter at all that the GFS is showing an initial pressure of 1009mb for the low pressure near Florida, when it is more like 1005mb (via Cross City, FL current conditions)?

the computers have been behind that curve all afternoon and evening

we sit and we wait

[jrodd321]

Just to be clear, you're not including PHL in that, are you? Because verbatim we make out just fine...

Yea he means south of Philly. We make out fine, man.

[ohleary]

We shall see what nails what come Monday morning. There are other models besides NAM and GFS as someguy has pointed out.

Wwhen you can compare the GFS and NAM precip fields inside 24h and they are locked in, should ya doubt it? Plus, have you looked at radar?

[Terpeast]

Watch for SLP off the coast of georgia at 1 am (6z). 0z GFS run shows sub 1004 there at 6 hrs... compare that with sfc obs at 1 am.

[mitchnick]

elongated 700mb Low is definitely killing us

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/ruc/hr4/index_700_l_loop.shtml

[lsukev]

You'd have to compare it to 00z, which is 7PM. Even though the GFS doesn't start outputting until around 1030, the initialization is showing conditions at 7PM Eastern time.

That makes perfect sense, but I seem to remember from earlier posts that the pressure has been below 1009mb for several hours now. Thanks!

[Srain]

MODEL DIAGNOSTIC DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

1028 PM EST SAT DEC 25 2010

VALID DEC 26/0000 UTC THRU DEC 29/1200 UTC

...SEE NOUS42 KWNO ADMNFD FOR THE STATUS OF THE UPPER AIR

INGEST...

00Z NAM EVALUATION INCLUDING PRELIMINARY MODEL PREFERENCES...

NAM INITIALIZATION ERRORS DO NOT SEEM TO DEGRADE ITS SHORT RANGE

FORECAST.

SHORTWAVE MOVING INTO THE PACIFIC NORTHWEST TUESDAY

NIGHT/WEDNESDAY MORNING...PREFERENCE FOR A NON-12Z UKMET

COMPROMISE

THE NAM HAS TRENDED STRONGER/QUICKER WITH THIS SYSTEM OVER ITS

PAST DAY OF RUNS. THE ECMWF HAS TRENDED STRONGER/SLIGHTLY SLOWER

WITH THIS SYSTEM OVER ITS PAST COUPLE DAYS OF RUNS. WHEN

COMPARING THE GUIDANCE...THE 12Z UKMET IS A SLOW OUTLIER WITH THIS

SYSTEMS PROGRESSION...WHICH HAS MINIMAL ENSEMBLE SUPPORT FROM THE

12Z GEFS MEMBERS...BUT NO CANADIAN OR ECMWF MEMBERS. WHILE ITS

SOLUTION IS POSSIBLE CONSIDERING BUILDING RIDGING UPSTREAM...WILL

FAVOR A NON-12Z UKMET COMPROMISE WITH THIS SYSTEM.

SHORTWAVE MOVING ACROSS NORTHWEST MEXICO AND TEXAS

MONDAY/TUESDAY/EARLY WEDNESDAY...PREFERENCE FOR A GENERAL MODEL

COMPROMISE

THE NAM HAS TRENDED SLIGHTLY QUICKER/EASTWARD WITH THIS SYSTEM

OVER ITS PAST DAY OF RUNS. THE ECMWF IS ON THE QUICK SIDE OF ITS

PAST COUPLE DAYS OF RUNS WITH THIS SYSTEM. THE MODELS SHOW GOOD

AGREEMENT WITH THIS SYSTEM...SO WILL PREFER A GENERAL MODEL

COMPROMISE HERE.

SURFACE LOW APPROACHING VANCOUVER ISLAND MONDAY NIGHT THROUGH

SOUTHERN CANADA...PREFERENCE FOR A QUICKER NON-12Z CANADIAN

COMPROMISE SOLUTION

THE NAM HAS TRENDED NORTH/QUICKER/DEEPER WITH THIS SYSTEM OVER ITS

PAST DAY OF RUNS. THREE OF THE ECMWFS PAST FOUR RUNS SHOWED A

PROGRESSION THIS QUICK...WITH ITS 00Z RUN THE SLOW OUTLIER OVER

ITS PAST COUPLE DAYS OF SOLUTION. WHEN COMPARING THE

GUIDANCE...THE 12Z CANADIAN BECOMES A SLOW OUTLIER WITH ITS

PROGRESSION. THE 12Z GLOBAL ENSEMBLE MEMBER CLUSTERING FAVORS THE

QUICKER NON-12Z CANADIAN CONSENSUS...WHICH MAKES SENSE CONSIDERING

THE ZONAL FLOW REGIME IN WHICH IT IS EMBEDDED...SO IT IS

PREFERRED.

NORTHERN STREAM SYSTEM MOVING ALONG THE US/CANADIAN

BORDER...PREFERENCE FOR A QUICKER NON-12Z CANADIAN COMPROMISE

SOLUTION

THE NAM HAS TRENDED QUICKER WITH THIS SYSTEM OVER ITS PAST DAY OF

RUNS. THE ECMWF IS ON THE MORE NEGATIVELY TILTED...QUICK SIDE OF

ITS PAST COUPLE DAYS OF RUNS. WHEN COMPARING THE GUIDANCE...THE

12Z CANADIAN WAS ON THE SLOW SIDE OF THE GUIDANCE...WITH A QUICKER

NON-12Z CANADIAN CONSENSUS PRESENT. SINCE THE TREND IS QUICKER ON

THE NAM/ECMWF...WILL FAVOR A QUICKER NON-12Z CANADIAN COMPROMISE

SOLUTION HERE.

SOUTHERN STREAM SHORTWAVE MOVING THROUGH THE SOUTHWEST/PLAINS/OHIO

VALLEY...PREFERENCE FOR A COMPROMISE OF THE 18Z GFS AND 12Z ECMWF

THE NAM HAS TRENDED QUICKER WITH THIS SYSTEM OVER ITS PAST DAY OF

RUNS. THE ECMWF IS ON THE QUICK/WEAK SIDE OF ITS PAST COUPLE DAYS

OF RUNS WITH THIS SYSTEM. THERE ARE TIMING DIFFERENCES WITH THIS

SYSTEM...WITH THE 18Z GFS SPLITTING THE DIFFERENCE. THE 12Z

CANADIAN IS THE QUICKEST SOLUTION. AS THE SYSTEM WILL BE MOVING

UNDER THE BASE OF NORTHERN STREAM RIDGING IN SOUTHEAST CANADA...IT

SHOULD REMAIN PROGRESSION...BUT SINCE THE NORTHERN STREAM RIDGE

ITSELF IS PROGRESSIVE...THE SOUTHERN STREAM SHORTWAVES MOVEMENT

SHOULD NOT BE EXCEEDINGLY QUICK...RULING OUT THE 12Z CANADIAN.

THE 00Z NAM IS THE SLOWEST...AND SINCE IT IS TRENDING

QUICKER...THINK ITS SOLUTION REMAINS TOO SLOW AS IT FITS ITS

TRADITIONAL BIAS 2-3 DAYS INTO THE FUTURE. DEPTH ISSUES PERSIST

WITH THE REMAINING GUIDANCE...AS THE 18Z GFS IS STRONGEST AND THE

12Z ECMWF IS WEAKER. WILL DEAL WITH THE UNCERTAINTY BY

COMPROMISING BETWEEN THE 18Z GFS AND 12Z ECMWF.

DEEP CYCLONE/NOREASTER MOVING UP THE EAST COAST...PREFERENCE FOR A

NON-12Z UKMET COMPROMISE SOLUTION

THE NAM HAS TRENDED SLIGHTLY STRONGER WITH THIS SYSTEM OVER ITS

PAST DAY OF RUNS BUT HAS OTHERWISE MAINTAINED GOOD CONTINUITY ON

ITS TRACK. THE ECMWF HAS TRENDED WESTWARD WITH THIS SYSTEM OVER

ITS PAST COUPLE DAYS OF RUNS. THE MODELS SHOW GOOD AGREEMENT WITH

THIS SYSTEM FOR THE MOST PART...INCLUDING THE 21Z SREF

MEAN...EXCEPT FOR THE 12Z UKMET WHICH FLINGS ITS EASTWARD OFF NOVA

SCOTIA RATHER THAN NORTHEAST. WHILE 12 OF THE 90 12Z GLOBAL

ENSEMBLE MEMBERS SUPPORT THIS IDEA...THE 12Z UKMET IS ON THE QUICK

SIDE OF THOSE MEMBERS. WILL FAVOR A NON-12Z UKMET COMPROMISE WITH

THIS SYSTEM. FOR PRECIPITATION/WINTER WEATHER IMPACTS...SEE THE

QPF AND WINTER WEATHER DISCUSSIONS AND GRAPHICS FOR MORE DETAILS.

...MODEL TREND GRAPHICS AT

WWW.HPC.NCEP.NOAA.GOV/HTML/MODEL2.SHTML...

...500 MB FORECASTS AT

WWW.HPC.NCEP.NOAA.GOV/H5PREF/H5PREF.SHTML...

ROTH

[pojrzsho]

Wwhen you can compare the GFS and NAM precip fields inside 24h and they are locked in, should ya doubt it? Plus, have you looked at radar?

OK.....so why does Midlothian, VA ALREADY have 3" of snow according to Midlo? No reason to doubt him, so what would that QPF be at ELEVEN PM12/25 be and what was it progged to be? A serious question, based on NAM and GFS.

[winterymix]

elongated 700mb Low is definitely killing us

http://www.nco.ncep....00_l_loop.shtml

I dunno...the whole storm seems sketchy in our area but the mets. here, almost to a man,

advise patience. A general 2 to 6 should calm the savage beasts here for a few days.

Gonna check it out in the morning. Where is weatherfella?...he should be knocking back some $28 a bottle pinot grigio and waxing his snow shovel and reminiscing about breaking up with the girl that asked him "Which is it gonna be -- me or the snowstorm?"

[lsukev]

Watch for SLP off the coast of georgia at 1 am (6z). 0z GFS run shows sub 1004 there at 6 hrs... compare that with sfc obs at 1 am.

Took your advice and went back to the 12Z GFS. The forecasted strength of the SLP near Cross City, FL was 1008mb, so it has been slightly underestimating its strength.

[Kenny G]

03Z RUC @ 12 hr shows 992 mb low just east of OBX looks like decent precip in VA

[mitchnick]

I dunno...the whole storm seems sketchy in our area but the mets. here, almost to a man,

advise patience. A general 2 to 6 should calm the savage beasts here for a few days.

Gonna check it out in the morning. Where is weatherfella?...he should be knocking back some $28 a bottle pinot grigio and waxing his snow shovel and reminiscing about breaking up with the girl that asked him "Which is it gonna be -- me or the snowstorm?"

if ratios were decent, we could get 6" ala 1/30/10

it was a lot colder though for that storm

[ohleary]

OK.....so why does Midlothian, VA ALREADY have 3" of snow according to Midlo? No reason to doubt him, so what would that QPF be at ELEVEN PM12/25 be and what was it progged to be? A serious question, based on NAM and GFS.

Looks like GFS nailed it, had Richmond at about .15 for the 6-hr period. NAM was a miss. Look at the QPF fields and the actual SE radar at this time. Envision the storm track, the enhancement of the sfc low and you can see (intiuitively) that the GFS and NAM seem to have a handle on it. At least I can. The only wild card is the low deepening and the precip field being enhanced to the west more for the MA to see more snow.

[PhineasC]

I am hugging the SREFs tight tonight.

[mitchnick]

if you click the animate box, you can see that snow should push into DCA/BWI shortly

GFS gave is some measurable precip while NAM kept it just south, so GFS may be the winner here

http://www.marylandw...m/klwxstate.php

on another note, check out the 18 hr precip map on the 3z RUC

sweet!

[TUweathermanDD]

if you click the animate box, you can see that snow should push into DCA/BWI shortly

GFS gave is some measurable precip while NAM kept it just south, so GFS may be the winner here

http://www.marylandw...m/klwxstate.php

on another note, check out the 18 hr precip map on the 3z RUC

sweet!

RUC getting better every run Mitch, hard to deny it, that and SREF's have been sharp as glass. Must hug them like Phin is.

[Amped]

Watch for SLP off the coast of georgia at 1 am (6z). 0z GFS run shows sub 1004 there at 6 hrs... compare that with sfc obs at 1 am.

Already 1004 In Jacksonville and Brunswick.

[Kevin Druff]

MidlothianWX probably has a bit more than .15" liquid. I am only about 10-12 miles due north of him and i only have a bit more than 2" accumulation (banding FTL)

[mitchnick]

RUC getting better every run Mitch, hard to deny it, that and SREF's have been sharp as glass. Must hug them like Phin is.

yes they are

look at the 700 mb at 18hrs

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/namer/ruc/hr4/images/ruc_700_018l.gif

[pojrzsho]

Looks like GFS nailed it, had Richmond at about .15 for the 6-hr period. NAM was a miss. Look at the QPF fields and the actual SE radar at this time. Envision the storm track, the enhancement of the sfc low and you can see (intiuitively) that the GFS and NAM seem to have a handle on it. At least I can. The only wild card is the low deepening and the precip field being enhanced to the west more for the MA to see more snow.

that would be a 20:1 ratio yes?

[Amped]

yes they are

look at the 700 mb at 18hrs

http://www.nco.ncep....uc_700_018l.gif

That tends to be too warm at the mid levels.

[TUweathermanDD]

yes they are

look at the 700 mb at 18hrs

http://www.nco.ncep....uc_700_018l.gif

Like the look of the UVV's and they have been pushed further and further west on that last frame. Well, this is the last post on my 5 limit, so I'll be watching from here out.

[lsukev]

Already 1004 In Jacksonville and Brunswick.

Yup, good call. I can't wait to see what happens when it gets over the Gulf Stream.

[Terpeast]

Looks like RUC/SREF vs GFS/NAM...we shall see who wins.

[lsukev]

I've got a good question regarding the models... thinking about how much trouble the tropical mets have with forecasting the intensity of tropical storms, why do we put so much stock into computer models to accurately forecast the strength of cold core storm systems? Are there less variables at play? Better data input into models?

Sorry if this is inappropriate for this thread.

[PhineasC]

Looks like RUC/SREF vs GFS/NAM...we shall see who wins.

Yeah, it is like night and day. SREFs are as sure as a set of models can be that DCA gets 5-7 inches. The overall model performance on this storm has been putrid. More busts, both good and bad, still to come up the coast, I suspect.

[mitchnick]

Yeah, it is like night and day. SREFs are as sure as a set of models can be that DCA gets 5-7 inches. The overall model performance on this storm has been putrid. More busts, both good and bad, still to come up the coast, I suspect.

IF SREF's are correct, with decent ratios based on -8C 850's, I could get 10"and you could get 12"

its possible, but only if the SREF's are right and a little luck w/ratios

a long shot, but possible

[mitchnick]

hey, GGEM better for MA!

12 hours

24 hours

[mitchnick]

GGEM 36 hrs

[am19psu]

I've got a good question regarding the models... thinking about how much trouble the tropical mets have with forecasting the intensity of tropical storms, why do we put so much stock into computer models to accurately forecast the strength of cold core storm systems? Are there less variables at play? Better data input into models?

Sorry if this is inappropriate for this thread.

Quickly, tropical systems are 10 mi wide, extratropical systems are 100 mi or more wide. It matters a lot at the model level.