Dr. Jeff Masters' WunderBlog

still trying to figure out why the GFS has such a hard time in the Northeast?

Seems it over emphasizes all parameters. Picks up cyclogenisis fairly well far out but the actual qpf, winds, ect seem overdone usually. At least thats what happened on the last 3 systems.

Been leaning to the WRF and MM5 as the better models with NAM and ECM/UKM close behind.

Actually, LOL, I blend things from each. I take bits and pieces from each as they seem to have better resolution for certain things.

No problem Storm. Glad I could help.

Morning 456

Good morning all! Hope you guys are handling the cold well. It was the second straight morning in the 40s here in Cooper City. I'm loving this weather and it looks like Christmas Eve and Christmas Day are going to feel like Christmas (for South Florida standards).

Hey 456, if you have time, could you give me a tutorial on how you derive those Cl numbers and how you recognize certain system types. I have been wanting to do analysis like that on my own for quite a while now. You could just send an email since I will be out from time to time today. It would be greatly appreciated.

morning CCH

test

Good morning Bonedog. How cold is it in your neck of the woods? I see what you and Storm have been discussing about this morning. You guys brought about some very good points. It is tough to throw out the GFS since, in my opinion, it is the most reliable computer model out there.

Test received weathermanwannabe. Good morning to you.

Morning CCH. Woke up to 22* winds light windchill 19* :)

I dont throw out the GFS models as they are pretty accurate but they do over emphasize certain things here in the Northeast.

I was looking up why and came across an interesting fact. This is from the NWS page disscusion of model suites...

The GFS model itself is a global spectral model truncated at total wave number T382 (equivalent to about 35-km horizontal grid spacing) with 64 vertical levels. This resolution is maintained through 180 hours of the forecast. Thereafter, the GFS is truncated to wave number T190 (equivalent to about 80-km grid spacing) with 64 vertical levels out to 384 hours.

Looking at how wide of a grid they use then looking at the Terrain in the Northeast one can infer (at least I did) that due to quickly varing terrain certain synoptic things can be missed.

Still researching though.

159. Bonedog 1:25 PM GMT on December 18, 2007
Morning CCH. Woke up to 22* winds light windchill 19* :)

I dont throw out the GFS models as they are pretty accurate but they do over emphasize certain things here in the Northeast.

I was looking up why and came across an interesting fact. This is from the NWS page disscusion of model suites...

The GFS model itself is a global spectral model truncated at total wave number T382 (equivalent to about 35-km horizontal grid spacing) with 64 vertical levels. This resolution is maintained through 180 hours of the forecast. Thereafter, the GFS is truncated to wave number T190 (equivalent to about 80-km grid spacing) with 64 vertical levels out to 384 hours.

Looking at how wide of a grid they use then looking at the Terrain in the Northeast one can infer (at least I did) that due to quickly varing terrain certain synoptic things can be missed.

Still researching though.

Very good point there Bonedog. You can clearly see the truncation occur when you run the GFS model. I did not factor in the varying terrain in the NE when considering these computer model runs. There is a vast difference between 35km grid spacing and 80km grid spacing, so that could explain some of the outliers produced by the GFS model. Thanks for the info. You come up with some fascinating info.

Hey 456, if you have time, could you give me a tutorial on how you derive those Cl numbers and how you recognize certain system types. I have been wanting to do analysis like that on my own for quite a while now. You could just send an email since I will be out from time to time today. It would be greatly appreciated.

i will send u an email with some info. But I caustion you: the Dvorak tecnique is headache. I have been doing since 2002 and I sill have difficulties, but once ur into it, that shud not be a problem.

wow looking up the diffrent models the NWS says the ECMWF is the most sophisticated they use!

Looks at the atmosphere in 4D and uses terrain following parameters in the boundry layers and puerly isobaric near the tropopause. and spaceing of 25km grided.

Very true Storm. Maybe the GFS foresees a change in the zonal flow. But, I do have to agree that with the current flow pattern based on water vapor imagery, the low should move into NC. I find VA to be a bit far north, but who knows.

Thanks 456. It can't give me a headache worse than learning Calculus and Statistics from a teacher who carries a unique mix of a Russian and Spanish accent arround.

Thanks for the heads up Storm. I havent looked at any imagery yet today. Was puerly going on models.

In my opinion, the metric system is much easier to handle than our English system since the metric system is based on powers of 10.

Yeah, it pretty much nails tropical systems...especially in the Pacific area. I would imagine since it's the European model, it may use metric values for intake and output.

I belive it does. Usually looking at the temp profiles usually in C*

It also appears to pick up the Nor'Easters well too. Right around the time they transfer the Low to the Coast the ECM is pretty accurate on where it forms and tracks.

Time to research more LOL. Guess today during the Lull of systems is a research day.

167. Bonedog 1:36 PM GMT on December 18, 2007
Thanks for the heads up Storm. I havent looked at any imagery yet today. Was puerly going on models.

When I do my forecasting, I tend to rely more on satellite imagery (mainly water vapor) than on computer models, although I do consider them a major factor into my forecasts. Just for fun, I showed some friends (who know very little about weather) the various computer models I study everyday and one actually started drooling since his mouth was wide open. I got a good kick out of that.

169. Bonedog 1:38 PM GMT on December 18, 2007
Yeah, it pretty much nails tropical systems...especially in the Pacific area. I would imagine since it's the European model, it may use metric values for intake and output.

I belive it does. Usually looking at the temp profiles usually in C*

It also appears to pick up the Nor'Easters well too. Right around the time they transfer the Low to the Coast the ECM is pretty accurate on where it forms and tracks.

Time to research more LOL. Guess today during the Lull of systems is a research day.

I never knew there was lull in the systems since the Northwest continues to get hammered this morning by the same system that will hit the Northeast later in the week going into the weekend.

Good morning JFV! How are your finals going thus far? I remember that you have your finals this week.

I do to CCH (look at imagery). Just haven't gotten around to it yet. Being Im at my job I have to take care of that first and usually model runs I can glance at and get an idea of whats going on. Imergy I have to look at a little closer. I get to that during lulls in my job (basically labor brakes).

When I say Lull in systems I mean between model runs. I will be following everything all day but with current information already out and anyalised gives me a few moments to do research.

Im a great multitasker but should clarify my statements better for folks.

Morning JFV

well JFV thanks for asking

This tropical cyclone has two outflow channels - one to the north and one to the south. The one two the south is more define. I define an outflow channel as a region in which outflow emanating from a tropical cyclone is focus. clockwise in the N hemisphere and anticlockwise in the S H.

oo another fun fact LOL

found out why the NGM model works well in the winter with systems....

Major parameters provided by NGM are ice covered water areas (yes/no), snow covered areas (yes/no), terrain height, mean sea level pressure, convective precipitation, total precipitation, exchange coefficient at surface, upward turbulent flux of sensible heat, upward turbulent flux of water, surface pressure, number of mixed layers next to surface, u component of wind, v component of wind, vertical velocity, specific humidity, and temperature

I think alot of models do not take into account snow / ice pack.

Some models seem to make the temps too warm. Like on this weekends system so models are showing the warm sector to reach 55 degrees. With current snow cover and recent cold air I doubt thats possible ( I may be wrong). Also I believe thats why a forcast can bust as far as type of precip. 55* would signify all rain but if the layer near the ground is still cold due to snow/ice cover a mixed precip event would be more probable

GM,all

morning NE

CCW thing with storm heading east out of texas is where does it reform over ocean. Storms approaching the coast always do and transfer their energy as they do.. I'm about to check storm's update to find out where.

Very cold this morning,brrrrrrrr.

Morning everyone. Quiet here in south Louisiana this morning. Lower to mid 40's...partly cloudy...and warming into the mid - upper 60's today. Back in the mid 70's tomorrow. :-(

187. Ivansrvivr 2:18 PM GMT on December 18, 2007
CCW thing with storm heading east out of texas is where does it reform over ocean. Storms approaching the coast always do and transfer their energy as they do.. I'm about to check storm's update to find out where.

I realize that Ivan, but you always want to track the low coming across the country since that could have a great impact on the weather in the Southeast, where we all need rain.

Morning all - a few minutes b/4 I'm off to work. Missed surfing the cold front waves on clean-up Monday - I was just in too much shock from the cold air temps. Gomex by me is 68 degrees. Due to the coming weak trough coming in thursday or Friday, I may get a chance this Friday ---just got to get over the whine and put the rubber suit on.

Bonedog some GREAT cold-front surf pictures from the jetties Venice can be found on gulfster.com and aurasurf.com

Good morning hondaguy. Already warming up that quick?

thanks surfmom. But if I look at them I will start to cry :( I miss those waves down there.

Now with water temps in the lower 40s and air temps in the 20s and lower 30s surfing is over for me till June or July.

The GFSx shows the next storm and another behind it..and another, and another..Link

I had to look :)

man I missed some great swell. Love that break.

yea Pat. talk about training.

My point is thats why we miss out on alot of it. If parent low isn't in GOM or close to it, or new low forming on tail of front, we miss almost everything else.

guess you gave me a reality check - I felt bad chickening out after I looked at the pictures, now hearing your conditions - I should just suck-it-up, just harder to stay warm the older I get ...and there were NO chicka's out - hopefully i'll adjust to the cooler temps, I know you'll are laughing - but once it gets below 60 I am miserable!!! Just can't keep warm.

Well, off to work, got to be sure the furry-four leggeds (horses) have kept their blankets on, and get them exercised. Can't believe last week I was complaining about 80 degree weather, and now I'm whining about the cold 53 degree --just like a woman - so hard to please. Pull out the hats, gloves, thermals --hate riding looking like a insulated snowman

Wednesday and Thursday's storm looks quite interesting for me on the Cape. Cape Cod is under the .5 to 1.0" of QPF combining the GFS and NAM which they both have trended further south with the bulk of the precip in their 6z for the GFS and 12z for the NAM. Looks interesting at best.

Patrap, that GFSx showed something try to form near yucatan then go poof. That would be a good one for Lake O if it popped and went NE.

LOL surfmom.

Yea I used to go out in these conditions but as you said its harder to get warmed up the older we get.

If I was done by you though 60* waters I would be in my spring suit maybe its all realitve though.


Have a good day and hope you catch some of the swells next time around.