Archive for November, 2009

mid week storm update, new GFS coming!

November 30, 2009

A: 1. The forecast for the week is on the last post. Here’s an update on how i see this Wednesday and thursday storm.

– low pressure tracks from Houston right up the west side of the Appalachians to Pittsburgh.

– heavy rains spread from south to north Wednesday

– rain lasts into the evening and ends as a period of wet snow as cold air rushes into the storm for areas west of I-75 just before rush hour Thursday with minor icy spots and some coatings to maybe under an inch for those folks.

– we all experience periods of snow showers thursday with maybe a coating on the highest se ridgetops Thursday night.

let’s break down the model runs 

00z nam

 

rain is moving into our region around noontime Wednesday with severe thunderstorms in progress across the south, a mix of rain and snow is ongoing across the ozarks.

by midnight periods of rain and even thunderstorms have moved through the region as the low tracks up I-75. however notice a dry slot feature when the cold air comes in this could limit any wrap-around snows just to the west of the track.

by thursday morning a quick hitting period of snow impacts areas from 1-65 west to St.Louis winds will also be increasing from the nw.

00z GFS

not much different than the nam at noontime Wednesday

This shows a track just west of the apps allowing for areas west of lexington to have the changeover to a period of snow early Thursday.

bottom line

– cold rain Wednesday

– rain to snow late Wednesday night from west to east,  

– snow showers thursday

– total accums through friday under 1 inch on grass with any slick spots minor.

B: there is an updated version of the GFS which will replace the current GFS later this month on the 15th.

more details click here

http://www.nco.ncep.noaa.gov/pmb/changes/

reading through i think it is a much needed major overhaul of the model. by the way this version of the model is running online.

link

 http://www.nco.ncep.noaa.gov/pmb/nwpara/analysis/namer/gfs/00/model_s.shtml

I would also suggest if you did not like the long range run of the old gfs you look at this one as past 144 hr it is quite different and more in line with my thinking. If you don’t want to look at it there’s always the 14 day forecast which I will be updating shortly.

 

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forecast for the next few days

November 28, 2009

1. Your weekend is shaping up nicely across the region with southerly flow and plenty of sunshine which will allow highs to get into the low and mid 50’s after morning lows near 30.  apologies for no post last night, I was working on revisions to my thesis proposal, now that the second of likely three revisions is done i have a free weekend for a change!

2. This will be ahead of the next frontal system, our much talked about dec 1 storm. The front should spread clouds into the area Sunday afternoon with a few periods of rain showers late Sunday and Monday. the majority of energy with this system will cut-off in the gulf of mexico leading to the main show later in the week. On the last post several days ago i was skeptical about the cut-off solution however this is now clearly shown by all of the models.  with this frontal passage Monday I don’t expect temps to rise much after falling into the lower 40’s sunday night, winds will pick up out of the nw as well.

3. Tuesday should be a cool sunny day behind the front in nw flow with some wind and highs in the mid 40’s, a typical winter day to start meteorological winter on the 1st.

3. Wednesday is when the cut-off low out of the gulf lifts north spreading rain and overcast skies into the region as morning temps stay in the upper 30’s. Rain should become hvy at times ahead of this low pressure Wednesday afternoon with highs only in the mid 40’s. The next blast of cold air then tries to catch the precip shield. This will likely result in a period of snow or snow showers late Wednesday night into Thursday Morning with strong n winds as temps fall to near 30.

4. Thursday should see some scattered snow showers continuing with quite a few spots picking up a coating.

5. The long range is tripping up the models at this point as some new factors come into play, however they indicate a trend toward a much colder pattern coming.

– the recuriving of typhoon niki, cases such as these can lead to east coast troughs

– the MJO has become more favorable for sustanied cold in the eastern US which can allow the polar vortex to move from sibera to north america.

– the AO and NAO are expected to go strongly negative

– the PNA is expected to stay around nuetral to slightly postive

 

Happy Thanksgiving

November 26, 2009

A Happy Thanksgiving to all of you.

A quick post today

– still expecting scattered rain showers today to flurries late tonight, I’ll update on the comments later today about our flurry chances

– the dec 1 system looked marginal at best even if the best case outcome occurred on those 12z gfs ensembles  if would have been an inch or two.

– a cold front should move through Monday with periods of rain showers possibly ending as flurries Tuesday morning as a week wave of low pressure moves northeast along the boundary and the residual energy is stuck over texas.

– I’m not buying the gfs solution of a secondary low in the gulf that rides north and phases with the next blast of cold air. By the way next week’s cold blast should be much stronger than what we’re experiencing to end this week.

– I’m thinking this energy over the texas and surrounding areas comes northeast toward next weekend dec 6th ish with another storm, with the cold air more established snow becomes an increasing possibility as the dominant precip type.

Holiday travel and Dec 1 storm update

November 25, 2009

1. My two main concerns for holiday travel Today and Thanksgiving continue to be wind and snow showers in the upper midwest and thunderstorms over central and southern florida.

2.  As for the Dec 1 storm the models are in a typical period of model mayhem with this system now.  My advice for you all now is not to take one solution as correct at this point as the models sort out the details. However after an encouraging 12z gfs run including the ensembles for snow lovers the 12z euro and new 00z gfs are warmer but with two different solutions. Both of these have rain as the main precipitation type , the 12z gfs had rain to snow.

00z gfs

12z euro

I’ll issue my first forecast on this storm tomorrow night.

12z GFS Ensembles very intresting

November 24, 2009

Ensembles are different simulations of the 12z gfs, it’s 16 runs of the 12z gfs. They show that the most used GFS version the operational is the furthest west of all of these runs with regards to the storm on Monday, in fact several of them bring the main axis of snow over Central Kentucky. These ensembles can also be an indicator in the trends of  the operational GFS. Also worth mention is the 12z Canadian also came out with a colder solution.

http://raleighwx.easternuswx.com/models/gfsensemble/members/12zf144.html

http://raleighwx.easternuswx.com/models/gfsensemble/members/12zf156.html

http://raleighwx.easternuswx.com/models/gfsensemble/members/12zf168.html