November 2014: Nice Seanonal Thanksgiving Ahead

[Andrew]

Concerning trends have been developing overnight in respect to this weekend's shortwave. Both the operational GFS and EURO have slowed down overall flow by a good 3-6 hours. This places the strongest mid level winds and vorticity right over SE Texas around 00z Sunday (6pm Saturday). Both models show strong PVA extending across the area with a LLJ streak extending over the Texas/Louisiana border, oriented from the SW to NE. The GFS has the farthest south track on the shortwave while the Euro takes a Central to Southern Texas track. The largest difference besides the slower track is the axis tilt associated with the 00z runs is that both models hint at a neutral or negative tilt, indicating a strengthening wave with strong veering winds across the region. Furthermore, the return in moisture from the gulf should raise dewpoints into the 60s with temps flirting with 70 degrees. If early junk convection can remain minimal, I suspect temperatures could be in the 70s prior to the front and that will really help increase CAPE. Overall trends have pointed towards a strengthening system that will likely lead to severe storms Saturday evening.

Euro 500mb:

ecmwfUS_500_spd_096.gif

Gfs 500mb:

gfsUS_500_spd_096.gif

GFS Skew T (Houston):

00_GFS_093_KIAH_skewt_SB.gif

GFS Skew T (College Station):

00_GFS_093_KCLL_skewt_SB.gif

Take a look at both of these skew-T charts. Take notice of the higher helicity values over Houston compared to College Station. This is due to the southern track of the shortwave along with the closer proximity to the LLJ. With this neutral to negative tilt of the shortwave, there is some pretty impressive bulk shear to go along with the veering. If the small inversion at the surface is just slightly overestimated, the LFC will shift closer to the ground, greatly increasing CAPE. As it stands right now, high winds looks to be the largest threat with supercells/tornadoes coming in second. This will be especially true if early morning convection can hold off.

[Katdaddy]

Very well stated Andrew! The potential continues to increase for a severe weather event across TX beginning across W Central TX Friday and spreading across Central and SE TX Saturday.

[SLM87TX]

Concerning trends have been developing overnight in respect to this weekend's shortwave. Both the operational GFS and EURO have slowed down overall flow by a good 3-6 hours. This places the strongest mid level winds and vorticity right over SE Texas around 00z Sunday (6pm Saturday). Both models show strong PVA extending across the area with a LLJ streak extending over the Texas/Louisiana border, oriented from the SW to NE. The GFS has the farthest south track on the shortwave while the Euro takes a Central to Southern Texas track. The largest difference besides the slower track is the axis tilt associated with the 00z runs is that both models hint at a neutral or negative tilt, indicating a strengthening wave with strong veering winds across the region. Furthermore, the return in moisture from the gulf should raise dewpoints into the 60s with temps flirting with 70 degrees. If early junk convection can remain minimal, I suspect temperatures could be in the 70s prior to the front and that will really help increase CAPE. Overall trends have pointed towards a strengthening system that will likely lead to severe storms Saturday evening.

Euro 500mb:

ecmwfUS_500_spd_096.gif

Gfs 500mb:

gfsUS_500_spd_096.gif

GFS Skew T (Houston):

00_GFS_093_KIAH_skewt_SB.gif

GFS Skew T (College Station):

00_GFS_093_KCLL_skewt_SB.gif

Take a look at both of these skew-T charts. Take notice of the higher helicity values over Houston compared to College Station. This is due to the southern track of the shortwave along with the closer proximity to the LLJ. With this neutral to negative tilt of the shortwave, there is some pretty impressive bulk shear to go along with the veering. If the small inversion at the surface is just slightly overestimated, the LFC will shift closer to the ground, greatly increasing CAPE. As it stands right now, high winds looks to be the largest threat with supercells/tornadoes coming in second. This will be especially true if early morning convection can hold off.

WHAT DOES THAT EURO MODEL EMPLY? WHERE WOULD STORM FORM AND WHAT DOES THAT DARK MAROON AREA MEAN? WHAT THE RAIN POTENTIAL OF THIS STORM?

[srainhoutx]

WHAT DOES THAT EURO MODEL EMPLY? WHERE WOULD STORM FORM AND WHAT DOES THAT DARK MAROON AREA MEAN? WHAT THE RAIN POTENTIAL OF THIS STORM?

First, those are the winds at 500mb or about a mile above the surface. The stronger veering winds are indicated by the brighter colors. Also, please turn off the ALL CAPITOL LETTERS typing... Excellent analysis Andrew. For those that do not know, Andrew is in his Senior year at Texas A & M getting his Meteorology degree. He will be our next Pro Met on our KHOU Weather Board and has grown up in our weather community and is now choosing to make his life long passion a career. This is where the Weather Forecasting Center is expecting the heaviest precipitation to fall. A note of caution, this is highly speculative this far out and is subject to change twice daily as they continue to evaluate the potential big storm system this weekend. The SPC (Storm Prediction Center) has already issued a Slight Risk for Severe Storms in their Day 3 Outlook which is a bit unusual unless they are confident the chances are pretty good for significant weather.

The attachment 11192014 10Z 5 Day QPF p168i.gif is no longer available

[SLM87TX]

Sorry for the Capital letters...and Congrats to Andrew!

[wxman57]

I was just going through my notes on the winter of 1976-1977, a good analog for this coming winter. Back in the mid 70s I was living in Lafayette, LA studying Chemical Engineering at USL (moved to Texas in the fall of 1977 to study meteorology at A&M). I kept a daily log of weather conditions in Lafayette, while commenting on weather events elsewhere across the country. As I looked through my notes from Oct/Nov of 1976 I saw some interesting things, like 8" of snow in Lufkin, TX on the 28th of October. At the top of my Oct/Nov sheets was written "Coldest October on Record" and "Coldest November on Record". Unfortunately the REAL cold was yet to come (January).

With that in mind, I've made a digital copy of my January 1977 records (below). The first page is my daily notes, which may be a bit hard to read as I used a type of shorthand. For example, FT = front through, so "FTEM" means "Front Through Early Morning".

It's the supplemental report on pages 2-4 that gave me the chills when I read it a few minutes ago. "Ohio River frozen solid. Ships breaking up in the ice". Mississippi River ice 20ft thick, including 10ft thick SOUTH of St. Louis. Temperature down to -60F in Wisconsin. Natural gas cut off to north - millions of students out of school. Florida declared a state of emergency. Snow in Miami.

So take a look at my supplemental report (after page 1) and decide if that's what you you cold lovers really want to see this winter. Very scary...

http://home.comcast.net/~cgh57/1976-1977.pdf

[ticka1]

I was just going through my notes on the winter of 1976-1977, a good analog for this coming winter. Back in the mid 70s I was living in Lafayette, LA studying Chemical Engineering at USL (moved to Texas in the fall of 1977 to study meteorology at A&M). I kept a daily log of weather conditions in Lafayette, while commenting on weather events elsewhere across the country. As I looked through my notes from Oct/Nov of 1976 I saw some interesting things, like 8" of snow in Lufkin, TX on the 28th of October. At the top of my Oct/Nov sheets was written "Coldest October on Record" and "Coldest November on Record". Unfortunately the REAL cold was yet to come (January).

With that in mind, I've made a digital copy of my January 1977 records (below). The first page is my daily notes, which may be a bit hard to read as I used a type of shorthand. For example, FT = front through, so "FTEM" means "Front Through Early Morning".

It's the supplemental report on pages 2-4 that gave me the chills when I read it a few minutes ago. "Ohio River frozen solid. Ships breaking up in the ice". Mississippi River ice 20ft thick, including 10ft thick SOUTH of St. Louis. Temperature down to -60F in Wisconsin. Natural gas cut off to north - millions of students out of school. Florida declared a state of emergency. Snow in Miami.

So take a look at my supplemental report (after page 1) and decide if that's what you you cold lovers really want to see this winter. Very scary...

http://home.comcast.net/~cgh57/1976-1977.pdf

Wxman57 - thank you for sharing with us your personal weather journal information. How interesting the information you provided what happened that year.

How many years have you kept weather journals?

[wxman57]

Wxman57 - thank you for sharing with us your personal weather journal information. How interesting the information you provided what happened that year.

How many years have you kept weather journals?

I started keeping a daily record my senior year in high school (1974-75) and ended late summer in 1977 when I left Lafayette for Texas A&M for my last 3 years of college. It's amazing that I've saved the records. I was always known as "weatherman" (wxman) back then. No internet, no computers, no Weather Channel. I watched every local TV station's weather broadcasts for my weather news. I remember trying to correlate the 6pm and 10pm temperatures with the next morning's low temperature. Wish I'd had Excel back then...

[jasons2k]

Thanks for sharing that. That was the first time I ever saw snow. I was living in Tampa, Florida at the time. I was barely 3 but I still remember going outside in my long pajamas to see it.

When I see the images of the Buffalo snow on TV I keep thinking 'this is like the famous '77 blizzards that JB would write about and I saw pictures of growing up'

I hope our January is nothing like that.

[unome]

incredible records you took and kept, thanks for sharing

I remember living through that winter in northern MN, also why I will never live there again...

a great site to view historical weather maps http://www.lib.noaa.gov/collections/img ... _maps.html

NOTE: Viewing the weather maps requires the free DjVu Browser Plug-In.
(available at the site)

[BlueJay]

Very interesting and so scary to read through those old notes wxman57! (nice handwriting, too!).

I am not a cold lover and definitely do not want this to happen again.

[srainhoutx]

Afternoon briefing from Jeff:


***Severe weather outbreak including tornadoes possible Saturday across much of SE TX.***

 

Strong storm system off the west coast currently will dive rapidly SSE and into the AZ/NM region on Friday and then sweep across TX on Saturday. Low level southerly winds have already returned to the region today ushering in much warmer temperatures and starting to increase moisture levels. Stronger moisture advection will begin on Thursday and stronger yet by Friday with increasing rain chances starting Thursday night. Lead short wave ejecting across on Friday with a chances of showers and thunderstorms in the warm air advection regime.

 

Concerning period is starting to key on Saturday afternoon as a powerful upper level system sweeps across central TX. Unstable warm sector air mass will likely have spread far inland by Saturday morning with dewpoints in the mid 60’s as maritime tropical air mass makes a return to the region. Impressive wind energy will come to bear on this unstable atmosphere as the low level jet is overrun by a strong mid level jet streak. This will result in strong low level turning with height and favorable low level shear for updraft rotation. Instability looks a little better today (800-1500 J/kg) which appears possible if not likely given the timing of the system in the mid to late afternoon allowing surface temperatures to rise into the mid to upper 70’s. I am concerned with the forecast low level shear values and long curved forecasted hodographs suggesting significant supercell potential in the warm sector ahead of the main band of thunderstorms. Tornado outbreaks almost always have these leading supercell storms in the warm sector that tend to produce the vast amount of tornadoes and damage. The GFS does attempt to develop warm sector supercells in a convergent band ahead of the main line of storms Saturday afternoon. We are still talking about 72 hours out which is far out in severe weather time frames, but the confidence in the event and model agreement is fairly high at this time range. With that, SPC has already placed a Day 4 slight risk outlook for all SE TX and if parameters continue to look favorable into Thursday and Friday an upgrade to a moderate risk is certainly possible.

 

Main threats appear to be tornadoes and wind damage in the noon to midnight time period on Saturday. I am tempted to favor the tornado threat higher in the southern 2/3rds of the area where instability is forecasted to be strongest, but since we are 72 hours out I think a general widespread threat is best at the moment.

 

This system and its severe weather impacts bears close watch especially on the tornado threat.

 

Note: record low of 30 degrees was established this morning at BUSH IAH breaking the 111 year old record of 31.   

 

SPC Day 4 (Saturday) Severe Weather Outlook:

 

[kennethb]

As a followup to wxman57, I note that I live in Baton Rouge and was here during the 1970's. I kept the daily highs and lows for a few years, though not in as much detail as wxman57. That winter is remembered. I think Buffalo had similar massive lake effect snows in November and December. Here in Baton Rouge we had a sleet storm the afternoon of November 28, with a trace of snow recorded, the earliest ever. And it was sometime in January that we had warm air advection snow. We actually started out as snow and slowly went to sleet and then a cold rain. Usually happens the other way.

[Ptarmigan]

I was just going through my notes on the winter of 1976-1977, a good analog for this coming winter. Back in the mid 70s I was living in Lafayette, LA studying Chemical Engineering at USL (moved to Texas in the fall of 1977 to study meteorology at A&M). I kept a daily log of weather conditions in Lafayette, while commenting on weather events elsewhere across the country. As I looked through my notes from Oct/Nov of 1976 I saw some interesting things, like 8" of snow in Lufkin, TX on the 28th of October. At the top of my Oct/Nov sheets was written "Coldest October on Record" and "Coldest November on Record". Unfortunately the REAL cold was yet to come (January).

With that in mind, I've made a digital copy of my January 1977 records (below). The first page is my daily notes, which may be a bit hard to read as I used a type of shorthand. For example, FT = front through, so "FTEM" means "Front Through Early Morning".

It's the supplemental report on pages 2-4 that gave me the chills when I read it a few minutes ago. "Ohio River frozen solid. Ships breaking up in the ice". Mississippi River ice 20ft thick, including 10ft thick SOUTH of St. Louis. Temperature down to -60F in Wisconsin. Natural gas cut off to north - millions of students out of school. Florida declared a state of emergency. Snow in Miami.

So take a look at my supplemental report (after page 1) and decide if that's what you you cold lovers really want to see this winter. Very scary...

http://home.comcast.net/~cgh57/1976-1977.pdf

Cool. Very interesting. 1976-1977 was a weak El Nino with a warming PDO. Negative NAO, AO, WPO, and EPO and positive PNA. Those contributed to a cold winter.

[cajun]

Sounds like someone else around here was a fan of Dick Faurot?

[Katdaddy]

Models continue to advertise a potentially significant severe weather threat for this weekend across a large portion of TX. I would not be surprised to see a Moderate Risk in later SPC forecasts for S Central and SE TX.
This afternoon's Houston-Galveston NWS Hazardous Weather Outlook sums it up well:

THE POTENTIAL FOR SEVERE WEATHER IS INCREASING AS A WESTERN UPPER LEVEL TROUGH ADVANCES INTO THE STATE SATURDAY. AS OF TODAY…IT APPEARS THAT THE GREATEST LIKELIHOOD FOR SEVERE WEATHER WOULD COME
IN THE FORM OF DISCRETE CELLS FORMING OVER CENTRAL AND EASTERN TEXAS SATURDAY. THESE CELLS COULD EVOLVE INTO A MORE ORGANIZED DOWNSTREAM SQUALL LINE FEATURE THAT WOULD AFFECT THE REGION DURING THE AFTERNOON HOURS. THE PRIMARY THREATS WOULD BE DAMAGING
DOWNBURST WINDS AND TORNADOES WITH THE SECONDARY THREAT OF BRIEF HEAVY RAIN EPISODES LEADING TO TEMPORARILY FLOODING ISSUES. THE PROGRESSIVE EASTERN MOVEMENT OF THE UPPER TROUGH SHOULD HAVE THE
SEVERE WEATHER THREAT ENDING BY EARLY SUNDAY MORNING.
.SPOTTER INFORMATION STATEMENT...
SPOTTERS SHOULD BE AWARE AND BE PREPARED TO MONITOR AND REPORT ANY SEVERE WEATHER OCCURRENCE SATURDAY.

[spadilly]

Travis Herzog posted this on his Facebook today. I found it really interesting. (Mods, I hope it's okay to post since it's from channel 13. If not, please let me know)

https://m.facebook.com/story.php?story_ ... 0656887594

Heads up! Our weather will radically shift from record-breaking arctic cold to a potential severe weather outbreak this Saturday.

One way to forecast the weather is to compare weather patterns predicted by computer models with similar weather patterns from the past. We call these past weather patterns "analogs." If you look at all the severe weather reports from the top 15 "analogs" for Saturday's predicted weather pattern, you get the following maps. One map I saved from yesterday's output, the other is from today's output. Both show a large number of tornadoes stretching from Texas into the Deep South.

Does this mean we're going to have a tornado outbreak on Saturday? No. Several of the analogs show NO severe weather at all.

But does this mean we *could* have a tornado outbreak on Saturday? Yes, it is possible, but only IF the current computer projections verify. The key here is the track and strength of an upper level low that is currently over the north Pacific Ocean where observations are sparse. As it gets closer to our observation network, I would expect the computer forecasts to shift a bit in the days ahead. We will see.

One interesting "analog" I see on both maps is October of 2006. On October 12-13, a major lake effect snow event took place over Buffalo, NY. Four days later, a major tornado outbreak occurred right here over Southeast Texas and Louisiana.

Fast forward to today. A major lake effect snow event just took place near Buffalo, NY. Four days later would be Saturday...will history repeat itself? Time will tell. The final map attached to this post shows the current "Day 4" severe weather outlook for the US, with a risk area drawn right over our part of the state.

[Andrew]

Model consensus continued to increase throughout the day today as the GFS, EURO, and NAM suggest a strong shortwave will cross Texas on Saturday. Currently, the slightly more southern scenario is gaining supporters as both the NAM and EURO show the base of the shortwave extending into South Texas. Overnight, moisture will continue to stream in from the gulf, raising dew-point temperatures and cloud coverage. This will also increase rain chances as gulf moisture advects northward. This trend will continue into Saturday as downstream surface ridging over the eastern part of the United States amplifies ahead of the wave. Expect temperatures to reach the 70 degree mark both Friday and Saturday with dews climbing into the mid 60s. Things get interesting Saturday evening as the shortwave's axis turns neutral/negatively tilted over parts of Central Texas. The exact location of this transition will be key for locating where the strongest storms setup. Latest data from the GFS suggests a slightly weaker low level jet along with a displaced jet streak, but an increase in 500mb winds and associated PVA. Timing of these vertical features has become a little more disorganized, but increased CAPE and overall orientation of the wave still leaves a very nice setup for severe weather. Surface winds will back throughout the day Saturday with a very defined veering profile in the vertical. Furthermore, models are more bullish with clearing skies prior to the shortwave arriving, resulting in more CAPE and steeper lapse rates (stronger updraft). Severe weather parameters look impressive, with CAPE ranging from 1000-1500 J/kg, wide sweeping hodographs, and helicity values ranging from 300-400. I expect thunderstorms to fire off early in the morning Saturday over Northwest Texas and track Southeast throughout the day. This will be supported by the front and a weak surface low over North Texas. High winds will be the largest threat with this MCS, but any storms that develop ahead of the line will have a good shot at going severe quickly. Both wind profiles and CAPE indicate that any cells that do develop have potential to put down a tornado.

There are a couple of things to keep an eye on as we get closer to the event. First off, there has been some disagreements between models on if and how far a weak backdoor front will track across East Texas Saturday morning. I suspect this is being overdone by most models and any impacts to the environment will be minimal. Next, the location and timing of the shortwave will be critical. As it stands right now, both shear and CAPE will be maximized across Southeast Texas but this can easily change with any adjustments in track. Finally, be careful with some of the gfs operational runs as convective feedback remains an issue in its parameterization of thunderstorms and the environment. Remember this event is still a couple of days off, but with that being said, I suspect we could see a moderate risk from the SPC before it is all said and done.

GFS 500mb Height and Wind Speed. Notice the generally neutral tilt on the shortwave and the 50+kt winds across the area:

gfsSGP_500_spd_072.gif

GFS 700mb Height and Wind Speed. Not as strong as previous runs and further displaced to the north.

gfsSGP_700_spd_072.gif

GFS 250mb Height and Wind Speed. Jet streak remains in South Texas, again slightly displaced from the mid level disturbance. You can also see hints at convective feedback in Northeast Texas (white shading)

gfsSGP_250_spd_072.gif

[Katdaddy]

Another excellent analysis by Andrew last night.

A 30% chance of showers today and tomorrow as the SE flow brings warming temps and GOM moisture inland across TX. Saturday continues to point to an active weather day across Central, S Central, and SE TX with the SPC upgrading the Slight Risk area to an Enhanced Risk. Damaging winds, large hail, and few tornadoes will also be possible. The primary threat will looks to be damaging straight line winds as storms possibly consolidate in a mesoscale convective system (MCS) and moves across SE TX from noon until late Saturday.

[srainhoutx]

Another great analysis from Andrew last night. The storm system that is expected to bring our severe weather episode is near the Pacific NW and will drop SE into Texas late Friday night. The short term meso guidance is trending to a very strong cool season severe weather outbreak across our Region with all modes of severe weather possible.