Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 5

[andyhb]

Snippet from the latest D4-8:

 

SATURDAY /DAY 6/ MODELS HAVE TRENDED TOWARD SIMILAR SOLUTIONS WITH
SPEED AND AMPLITUDE OF A MORE SUBSTANTIAL SHORTWAVE TROUGH THAT WILL
MOVE INTO THE SRN PLAINS SATURDAY AND CONTINUE INTO THE MS VALLEY
LATER SATURDAY NIGHT. GIVEN THE ANTECEDENT FRONT IS NOT EXPECTED TO
PENETRATE THE GULF...MORE SUBSTANTIAL MOISTURE RETURN AND
INSTABILITY SHOULD OCCUR IN ADVANCE OF THIS FEATURE SUPPORTING
POTENTIAL FOR A MORE ROBUST SEVERE THREAT FROM TX INTO A PORTION OF
THE LOWER MS VALLEY. AN ENHANCED SEVERE RISK AREA WILL LIKELY BE
INTRODUCED ON THE NEXT 4-8 UPDATE FOR A PORTION OF THIS REGION IF
MODEL ENSEMBLES CONTINUE TO DEMONSTRATE CONSISTENCY.

[Srain]

Impressive storm shaping up across our Region this weekend.

 

DAY 4-8 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   0400 AM CST TUE NOV 18 2014

   VALID 211200Z - 261200Z

   ...DISCUSSION...
   A PROGRESSIVE FLOW REGIME WILL CHARACTERIZE THE UPPER PATTERN OVER
   THE U.S. DAY 4 INTO DAY 5...BEFORE A RETURN TO A BLOCKING PATTERN
   WITH AMPLIFICATION OF A LARGE-SCALE TROUGH DAYS 6-8.

   DAYS 4-5...PARTIALLY MODIFIED GULF MOISTURE WILL ADVECT NWD THROUGH
   CNTRL/ERN TX IN ADVANCE OF A SRN STREAM SHORTWAVE TROUGH THAT IS
   FORECAST TO REACH THE SRN PLAINS EARLY DAY 5 AND CONTINUE THROUGH TX
   INTO THE LOWER MS VALLEY REGION. MODEST AMPLITUDE AND TIMING
   DIFFERENCES EXISTS AMONG ENSEMBLE MEMBERS. ALSO THE NAM IS SLIGHTLY
   FASTER AND LESS AMPLIFIED THAN THE ECMWF AND GFS WHICH ARE BOTH
   SIMILAR AND HAVE SHOWN RUN TO RUN CONSISTENCY. GENERAL PATTERN WOULD
   SUGGEST A THREAT FOR SEVERE STORMS MAY DEVELOP OVER PORTIONS OF
   CNTRL TX EARLY SATURDAY AND SERN TX INTO THE LOWER MS VALLEY LATER
   SATURDAY INTO SATURDAY NIGHT. STORMS WILL LIKELY GROW UPSCALE INTO
   AN MCS...BUT TENDENCY MIGHT BE FOR THIS ACTIVITY TO DEVELOP EWD MORE
   QUICKLY THAN THE ATMOSPHERE CAN DESTABILIZE SUFFICIENTLY WITH EWD
   EXTEND INTO THE LOWER MS VALLEY.

   DAY 6...SOME SEVERE THREAT WILL LIKELY PERSIST FROM SRN PARTS OF THE
   GULF COASTAL STATES TO THE CAROLINAS. HOWEVER...AT THIS TIME TOO
   MUCH UNCERTAINTY EXISTS REGARDING EXTENT TO WHICH ONGOING CONVECTION
   WILL LIMIT DESTABILIZATION POTENTIAL.

   ..DIAL.. 11/18/2014

 

 

 

 

[1900hurricane]

CIPS analogs for what they're worth paint an interesting picture. I'm also somewhat surprised HGX only just mentioned Saturday with one sentence in this morning's forecast discussion, especially with the entire forecast area in the heart of the SPC Day 5 risk area.

Sent from my iPhone using Tapatalk

[andyhb]

FWD usually doesn't include wording this strong this far out (from afternoon AFD).

 

WE ARE BECOMING CONCERNED FOR SEVERE THUNDERSTORMS SATURDAY
AFTERNOON/EVENING...WHEREVER THE SURFACE WARM SECTOR EXISTS AND
ALONG THE TRACK OF THE COLDEST TEMPERATURES ALOFT. SEVERAL OTHER
FACTORS WHICH WILL ENHANCE THE SEVERE POTENTIAL ARE: STRONG MID
LEVEL LAPSE RATES AROUND 7.5 C/KM...A 90 KNOT UPPER JET...STRONG
ISENTROPIC ASCENT...500MB CORE TEMPS DOWN TO -22C...A
STRATOSPHERIC INTRUSION DOWN INTO THE 500-400MB RANGE...AND 0-6KM
BULK SHEAR UP TO 60 KNOTS. THERE ARE SOME MODEL DISCREPANCIES WITH
THIS SYSTEM. THE CANADIAN DRAGS A COLD FRONT INTO THE CWA
FRIDAY NIGHT WHILE THE GFS/ECMWF PUSHES A PACIFIC FRONT THROUGH ON
SATURDAY. THE ECMWF PUSHES THE MAIN COLD FRONT THROUGH ON SUNDAY
WHILE THE GFS DOES SO LATE SUNDAY NIGHT.

[Srain]

A very informative evening briefing from Jeff:

 

First freeze of the winter season recorded at IAH this morning with the temperature falling to 32. Very interesting pattern of low temperatures outlined the urban sprawling across Harris and surrounding counties this morning defining heat corridors from development patterns. I will touch on this more below.

 

Temperatures have tumbled this evening with excellent radiative conditions in place. IAH fell 13 degrees since the sun has set from 53 to 40. Dewpoints currently in the upper 20’s and low 30’s support another freeze and this is favorable given this is night two after cold frontal passage which tends to be the coldest night. However the axis of the arctic surface high is centered in the Beaumont and Lake Charles area and surface observations show southerly winds across at least the western half of SE TX which suggest the temperature tumble will be halted as warmer air is brought inland from the Gulf of Mexico. With that said, would not be surprised to see temperatures approach freezing around midnight or shortly after along and northeast of US 290 and then rise some toward morning. It is very possible it will be colder at 1000pm tonight than at 600am tomorrow morning.

 

Sustained warming trend will begin on Wednesday after over a week of well below normal temperatures. In fact the gravity of this cold air outbreak can be noted in the record low recorded at Amarillo this morning of 5 degrees and across the nation with nearly 50% of the country with snow cover (33% is average on Christmas Day). The entire state of OK was covered in snow yesterday morning and Dallas recorded a record snow amount of a trace on Monday morning with many locations over N TX having a dusting of snow. Currently November 2014 is running an astounding 8.0 degrees below average for Houston and is currently ranked as the 9^th coldest November on record. While a colder and wetter than normal winter is expected across the southern plains, the current cold air outbreak has little bearing on what the rest of winter may exhibit especially with respect to any sustained severe cold air outbreaks and one should be cautious in drawing any conclusions from the recent cold spell and how the rest of winter may play out.

 

As the large arctic high moves eastward southerly onshore winds will begin to promote moisture return northward. A coastal surface trough will form off the lower TX coast Wednesday and help sling moisture over the top of the surface cold dome. This will result in an increase in cloud cover and can many times slow air mass modification. Chances for rain return by Thursday as a lead short wave in the developing flow aloft moves across TX and interacts with the developing moisture return. Warm front should move inland on Friday with scattered showers continuing to stream northward off the Gulf. Temperatures will warm into the 70’s south of the warm front and dewpoints will rise into the low to mid 60’s. While normally November is not a big sea fog month along the upper TX coast, the recent cold has chilled the bay and nearshore waters into the 50’s. With dewpoints rising into the 60’s or above that of the water temperatures, sea fog will be possible Friday afternoon into Saturday.

 

Saturday:

Strongly dynamic storm system suggested by model guidance for this Saturday with potential threats for both severe weather and heavy rainfall. Powerful short wave will dive into the southern jet and eject rapidly out of New Mexico into TX on Saturday while the system takes on a slight negative tilt or from SE to NW which suggest little to no SW flow in the mid levels to cap off the air mass. Mid level temperatures look very cool with the storm system which will help promote an unstable air mass only with surface temperatures in the 70’s. Low level shear values look favorable for updraft rotation. Main severe limiting factor at  the moment looks to be instability (CAPE of 500-1000 J/kg) across the area. SPC has already highlighted all of SE TX for a severe risk on Saturday with damaging winds and tornadoes likely being the main threats. The far southward placement of the core dynamics with this system suggest a threat is justified. It should be noted that October and November are our secondary severe weather season in SE TX and one of our worst tornado outbreaks ever recorded happened on November 21, 1992 when 4 large supercell thunderstorms produced 6 long tracked tornadoes across Harris County including a devastating ¾ of a mile wide F4 tornado in Channelview. The rest of the week focus will be on the Saturday system and its potential impacts.

 

The Urban Heat Core:

It has been known for a long time that urban sprawl can alter temperature and weather patterns on local scales. This was first studied in Atlanta in the 1990’s when it was noticed that unusually heavy rainfall was occurring in the late night hours during the summer months. Houston has been no exception to urban development especially on its west and northern flanks in the last few decades and is very clearly noted on clear and cold nights such as last night. Technology and the plethora of temperature data now available between official reporting sites gives a glimpse into just how widely varying the temperatures extremes can be over just a few miles. Low temperature data last night showed very interesting patterns of significantly warmer temperatures along I-10W, US 59S, I-45N, and along HWY 6 between US 290 and I-10. Temperatures along these “urban corridors” ranged anywhere from 3-8 degrees warmer than temperatures only a few miles away. What was striking is how closely the temperature patterns mirrored the major freeways and how “warm” western Harris County temperatures were especially in the Hwy 6 corridor. These observations are far from scientific as the various sensors being reported from home temperature gages are surely not all uniform nor likely all installed equally. Additionally, many of these sensors are likely within subdivisions which already create a warmer background temperature effect so the data set is not easily ready for direct comparison. Another consideration last night was the high clouds which crossed the area and what affect that may have had on the low temperature patterns. A better case could probably be made for tonight if winds were not shifting to the south late.

 

What can be drawn from the data is that urbanization is certainly resulting in warmer temperature readings especially under strong raditional cooling conditions. It is also noted that significant temperature differences over a very short distance are almost certainly creating microscale surface temperature boundaries during the warmer season which could help foster thunderstorm development. These boundaries are likely on the order of a few miles long and maybe less than 1/4^th of a mile wide which cannot be detected on Doppler radar nor high resolution model guidance, but given the temperature discontinuity noted in the data on a clear cold night suggest a similar pattern is likely present on a hot summer day. It is likely that the climate record at BUSH IAH is starting to be skewed due to urban development surrounding the airport with Hooks (Tomball) likely a more representative station for the remaining rural areas of Harris County. The urban heat core has loosely been defined as the area within the 610 loop, but it is clear that development has been sustained enough to likely expand that area to include areas inside Beltway 8 and also to include areas near/along the major freeway systems. It is almost certain that construction of the Grand Parkway system and its resultant urban development along that system will expand the urban heat core outward to the far outer reaches of Harris County over the next decade and into surrounding counties. Had I been at my office computer I would have “snagged” the temperature map, but I am sure another clear cold night without cloud cover will happen again in the next 2-3 months.

 

 

[1900hurricane]

From HGX regarding the recent cold:

 

 

CLIMATE... HOUSTON RECORDED A RECORD LOW OF 30 DEGREES WEDNESDAY
MORNING. THE HIGH TEMPERATURE WEDNESDAY AFTERNOON WAS 69 DEGREES.
THE HIGH IS SIGNIFICANT BECAUSE HIGH TEMPERATURES HAVE NOT EXCEEDED
58 DEGREES SINCE NOV 11TH. THE LAST TIME HOUSTON RECORDED 7
CONSECUTIVE DAYS WITH HIGH TEMPS AT OR BELOW 58 DEGREES DURING THE
MONTH OF NOVEMBER WAS BACK IN 1907. THE TEMPERATURE WAS BELOW 58
DEGREES BETWEEN 11/11/1901 AND 11/18/1907. THAT WAS ALSO THE LAST
TIME (UNTIL THIS YEAR) THAT HOUSTON SUFFERED A DAILY AVERAGE
TEMPERATURE DEPARTURE GREATER THAN 10 DEGREES PER DAY FOR EIGHT
CONSECUTIVE DAYS.

1907 2014

DATE TEMP DEP DATE TEMP DEP

NOV 11 45 -18 NOV 12 51 -13
NOV 12 40 -24 NOV 13 41 -22
NOV 13 42 -22 NOV 14 41 -22
NOV 14 43 -20 NOV 15 48 -14
NOV 15 51 -12 NOV 16 50 -12
NOV 16 45 -17 NOV 17 44 -18
NOV 17 50 -12 NOV 18 44 -18
NOV 18 50 -12 NOV 19 50 -11

[bubba hotep]

I know everyone is focused on this weekend but did anyone look out towards Day 10 on the 00z Euro last night?

[Srain]

I know everyone is focused on this weekend but did anyone look out towards Day 10 on the 00z Euro last night?

The is some ensemble support from the Euro and NAEFS mean for that solution. The WPC tossed the GFS/GEFS solutions in their Extended Range Discussion early this morning.

[DFWWeather]

I know everyone is focused on this weekend but did anyone look out towards Day 10 on the 00z Euro last night?

 

Yes, I did take note. It is starting to be some support for another Arctic dump in 6 to 10 days into the center of the nation, which is about that time on the ECMWF. The op model was also showing the cold air yesterday at 0z, not so much a 12z, but no winter precip. Today's is 0z is the first to show that.

[Quixotic1]

12z more progressive.  Speeds up timing and shortens duration of the arctic dump.  Sorta like last winter's episodes.  

[DFWWeather]

12z more progressive.  Speeds up timing and shortens duration of the arctic dump.  Sorta like last winter's episodes.  

 

Yes, but the ECMWF control does not. In fact, its 500mb pattern remains highly amplified well into the first week of December with possible 3 Arctic surges coming our direction. I think this has merit as the mean trough position should be in the center of the CONUS. If the ridge hooks over the top of pole, then blocking does develop. Arctic oscillation is forecasted to go negative during same time period. I've noticed for the last several runs of the ECMWF operational that the 0z and 12z runs seem to be a little out of phase with 12z always being warmer, even during the last Arctic outbreak. It'll be interesting to see what the 0z has on tomorrow. All of the models seem to be in mayhem right now, more than usual. The GFS has been almost pure rubbish the entire month. I noticed that the local NWS AFD this afternoon went with the GFS for the Thanksgiving weekend. That's almost a certain bust. The other area offices are not doing that, they are cautiously acknowledging the ECMWF's solution, Canadian is also lending toward the colder solution.

[canderson]

Tomorrow will be highly interesting. Wishing everyone at the HS and college games safety. Lots of games already moved up many hours, Baylor eyeing a move to Sunday.

[Quixotic1]

Wow. This might be the biggest dud ever. 95% chance of 1" or more. 0.25 in the gauge.

[bubba hotep]

Wow. This might be the biggest dud ever. 95% chance of 1" or more. 0.25 in the gauge.

And the Mid-Atlantic subforum stole our snow storm! Now it looks mild and dry next week....

[DFWWeather]

And the Mid-Atlantic subforum stole our snow storm! Now it looks mild and dry next week....

 

I don't know about that. The 0z ECMWF has an Arctic/Polar front damming in the Texas Panhandle on Friday. I've seen this time and time again and the cold almost always wins out and pushes through. I smell huge bust potential on temperatures for next weekend here in DFW. Think the GFS is out to lunch yet again. Current forecasts are calling for mid to upper 70s. Yikes!

[Quixotic1]

And the Mid-Atlantic subforum stole our snow storm! Now it looks mild and dry next week....

We'll have our chances but I wouldn't look for anything before the 10th. That Aleutian High has been a universal feature on the models. Twiddling thumbs.

[bubba hotep]

We'll have our chances but I wouldn't look for anything before the 10th. That Aleutian High has been a universal feature on the models. Twiddling thumbs.

 

I think the 10th +/- a couple of days is a good time frame to start eyeballing, esp. with the way the MJO is looking.  However, the models seem to want to tease an earlier dump of cold but can never pull everything together.  

[Quixotic1]

I think the 10th +/- a couple of days is a good time frame to start eyeballing, esp. with the way the MJO is looking.  However, the models seem to want to tease an earlier dump of cold but can never pull everything together.  

 

12z upgraded GFS looks promising.  Pops a strong west coast ridge and the Aleutian low starts to reform about day 10.  Also, all the teleconnections look to go our way late.  -AO, -NAO, -EPO and +PNA.  It's a long ways away and I've yet to see the euro but it looks like the flip is starting to show up.  

[DFWWeather]

Looks like the Arctic front pushing down the Plains this weekend, will push on through into DFW, albeit later than I was thinking (now on Monday). Something I've been watching all week (and last). Seems the afternoon update from FWD AFD agrees. Arctic air usually does not bottle up that close to our north.

[bubba hotep]

The 18z ParaGFS has a day 10 look that appears to be supported by a few of the 12z EPS members today.  Maybe the models are starting to pickup on something?  Probably a bit quick on the draw, still think the 10th +/- is the sweet spot.

[bubba hotep]

FWD mentioned a chance of freezing drizzle across the northern areas on Monday.  I'm starting to lose faith in a flip to a colder pattern around the 10th... maybe later in the month?  That would jive with El Nino but things in the atmosphere don't look terribly El Ninoish right now.  The only bright spot I see in the guidance right now is the Euro Weeklies with a colder look towards the end of December. I'm still putting a lot of stock in the evolution of the MJO and thinking it can get into 8/1, maybe?

[DFWWeather]

Arctic cold front racing southward this afternoon. It will reach DFW a little bit sooner than forecasted now between 2 and 3am. Temperatures will be some 35 to 42 degrees colder tomorrow from Today's high temperatures.

[bubba hotep]

There really is nothing to be stoked about at this point, maybe we can squeeze out a thunder shower Thursday night or Friday? I guess there are some signs emerging that we could get back to some winter action later in the month and I still feel good about Jan/Feb. Maybe we need a new thread to shake off this funk the weather has fallen in?

[Quixotic1]

I'm still confident a flip is coming.  I think my December 10th call is early.  Probably 15th - 20th.  1965, 2002 1977 had torch Decembers and the rest of the winters were good to great.  2002 flipped Christmas week and we got light snow on Christmas Eve.          

[1900hurricane]

A potent trough looks like it'll affect us in some fashion about eight days out or so. The ECMWF has been remarkably consistent with it the past four model runs since it entered the model's forecast range. Looks like a possibly stormy next weekend.

[bubba hotep]

A potent trough looks like it'll affect us in some fashion about eight days out or so. The ECMWF has been remarkably consistent with it the past four model runs since it entered the model's forecast range. Looks like a possibly stormy next weekend.

I've been keeping an eye on that, esp since things are pretty much a bore in the meantime. FWD mentioned it this afternoon after a lengthy discussion on a series of mostly dry systems.

That could possibly be the start of things finally getting interesting. I went back and looked at some stuff last night and feel much better about the end of December into February. Of course, someone is trolling Twitter this afternoon with MJO diagrams from December '94 lol

[Quixotic1]

94-95 was a toaster bath winter. Ugh.

Regarding the MJO, if it stays in the COD it'll be alright. If it pops up in 4-5-6 again it might be time to worry. Judah Cohen's blog from today seemed pretty confident. HM from this site seems pretty confident as well. If we're still looking at this scenario 2-3 weeks from now then I will worry......

[bubba hotep]

94-95 was a toaster bath winter. Ugh.

Regarding the MJO, if it stays in the COD it'll be alright. If it pops up in 4-5-6 again it might be time to worry. 

 

I typically don't worry a whole lot about the MJO in the winter, esp if it is low amplitude.  However, I have glanced at some stuff on MJO lag times that looks encouraging but I left the paper on my desk at work.  

 

 

 Judah Cohen's blog from today seemed pretty confident. HM from this site seems pretty confident as well. If we're still looking at this scenario 2-3 weeks from now then I will worry......

 

Yeah, I think things are looking pretty good right now but getting up in the 70's always makes me nervous     But like I said in earlier post, I felt more confident about things after going back over some analogs and what not.  And then Sam posted this on Twitter this afternoon:

 

 

and HM posted this the other day:

 

 

Some interesting stuff for sure. 

[DFWWeather]

I typically don't worry a whole lot about the MJO in the winter, esp if it is low amplitude.  However, I have glanced at some stuff on MJO lag times that looks encouraging but I left the paper on my desk at work.  

 

 

 

Yeah, I think things are looking pretty good right now but getting up in the 70's always makes me nervous     But like I said in earlier post, I felt more confident about things after going back over some analogs and what not.  And then Sam posted this on Twitter this afternoon:

 

 

and HM posted this the other day:

 

 

Some interesting stuff for sure. 

 

Has anyone seriously looked at the 1950-51 winter as an analog. I know it wasn't an El Niño winter that year, but our winter so far has been following it remarkably close. That was the year that we set the all time record cold of 19°F for November at DFW about the same time we had or near record cold blast this year, in almost an identical setup. In December, mild just like this year and this lasted most of the month with exception of Arctic blast around the 5th that year, but we had one five days earlier this year and much quicker and not as cold. The change started happening mid January. As we went into latter part of January, it got brutally cold here into early February, then it started getting mild for February with one more Arctic blast middle of the month. I believe the water temp profile of the Pacific is pretty similar to this year near North America, not so much in the central Pacific. There was warm water off the West Coast into the Gulf of Alaska. I think the PDO was in a colder cycle then as well. To me this seems a tad bit better fit then the winters of the late 70s. I'm thinking there will be a turn around in January leading to colder weather. December being mild is not surprising to me after the record warmth in October (which by the way October was exceptionally warm in 1950 as well).

[Srain]

The GFS and Euro continue to advertise a powerful bowling ball 5H low tracking across the Great Basin/ 4 Corners into Texas next weekend. As this cold core upper low wraps up and the trough axis takes on neutral/ negative characteristics, heavy mountain snows across New Mexico are possible extending into West Texas and the Panhandle as lee side cyclogenesis rapidly develops.

Across the warm sector, heavy elevated storms are possible that may become surface based E of the developing dry line. Moisture off the Western Gulf should further assist with developing a heavy rainfall chance across portions of the eastern half of Texas into Louisiana. If the guidance is correct, PW's near the 99th percentile for December could be possible.