December 2014: New Year's Eve Wintry Mix Possible

[snowman65]

Bah-humbugg....!

[djmike]

Wow...seems that the "long-lasting" cold is late for this time of year. Especially if our next really cold shot is'nt until after Christmas....Dec. 4 2009 we had 3-4" of snowfall on this date!

[srainhoutx]

Wow...seems that the "long-lasting" cold is late for this time of year. Especially if our next really cold shot is'nt until after Christmas....Dec. 4 2009 we had 3-4" of snowfall on this date!

After an unusually cold and dreary November that brought record breaking cold across much of North America, I think everyone expected the pattern to relax a bit. As we have talked about over the years, we live in the mid latitudes where extreme cold is a rarity versus wall to wall cold. Give it time. Even the very long range CFS ensemble mean is suggesting that pattern flips back to a 'colder regime' near Christmas.

12042014 00Z CFS cfs-avg_z500a5d_nhem_5.png

[BlueJay]

Even the coldest winters have warm periods courtesy of zonal upper air flow. I have seen it like in 1972-1973, 1976-1977, 1977-1978, and 1983-1984.

Is this an omen for what kind of weather we may have this winter?

Forecasts change. I'm going to try to enjoy each day and deal with whatever weather that we get.

Have a great day everyone!

[srainhoutx]

Morning briefing from Jeff:

Messy morning across the region with sea fog, rain showers, and drizzle.

Surface warm front pushing northward across SE TX this morning allowing a warm humid air mass to return. Surface dewpoints running in the mid to upper 60’s over the upper 50 to lower 60 degree water temperatures along the coast and in the bays is resulting in dense sea fog banks. Nearshore observations have shown 0-.25 mile visibilities overnight with coastal sites bouncing around from .25 -.75 of a mile. Visibilities and ceilings have been all over the place from the coast inland as sea fog banks spread inland from the coast at various times. Additionally showers moving northward in the warm air advection regime have increased visibilities in those areas.

Southerly winds today should help to scatter out the sea fog inland and near the coast and possibly even over the nearshore waters. More ideal sea fog setup is a ESE to E wind versus a south wind. An E wind allows a longer period of time for the warm air to travel over the cold water temperatures creating a more favorable sea fog set up. Short wave over CO helping to produce lift and scattered showers this morning will pass north of the region today. Should see shower activity begin to decrease early this afternoon as lift ends.

Big question for tonight is when will the sea fog return and how far will it spread inland. Weak frontal boundary will approach overnight and cause winds to weaken and even back a little to the ESE and with dewpoints remaining well above water temperatures think sea fog is almost a given. In fact coastal sections may only break out for a few hours this afternoon before they crater again near sunset this evening. Sea fog will likely spread inland at least to I-10 tonight into Saturday morning. Short term guidance has been hitting the fog signal pretty good again for tonight and did very well last night. Additionally, another disturbance aloft will move across SE TX and act with the incoming frontal boundary to produce scattered showers into Saturday morning so this activity may result in widely varying visibilities over the region as gusty winds near the showers help to scatter out the fog banks.

Weak front limps offshore and stalls allowing cooler and drier air to bleed into the area. This will lower rain chances Saturday evening and night, but this looks brief as yet another disturbance rapidly approaches on Sunday and results in moisture overrunning the surface cool dome. GFS is much stronger with this system than the ECMWF and if the GFS is correct much better rain chances will be required on Sunday. Temperatures will cool from the current warm and muggy values into the low to mid 60’s for highs on Sunday.

Not much improvement next week as disturbances aloft and retreating frontal boundary pretty much repeat this week. Sea fog, drizzle, showers and mainly cloudy but warm conditions appear likely at least into the middle of next week.

Longer range pattern shows little change with zonal flow aloft and a fairly dreary pattern in place. Cold air remains locked in Canada with no real delivery pattern southward at least through the next 5-10 days.

Marine:
Thick sea fog banks creating visibility issues near the coast and in the bays. Vessel pilots entering Galveston Bay have been reporting very low visibilities overnight and coastal web cams confirm the very low visibilities. Galveston has shown some improvement in the last hour with increased visibility from .50 of a mile to 3.0 miles however they have been reporting fog now for 12 hours straight. Expecting slow improvement within Galveston Bay today and then back down to low visibilities by late afternoon and likely most of the night. Matagorda Bay will likely see better improvements today with a more southerly wind fetch and not as confident that area will see as thick of sea fog tonight. Frontal boundary arriving early Saturday should help push the sea fog offshore and end the threat at least for a few days.

[srainhoutx]

A quick update on the longer range as we near mid December. The global models are suggesting a fairly significant Southern Rockies/Southern Plains storm system as the pattern begins to transition back to a bit cooler regime. If the guidance is correct, we could see a potent storm that has the potential to bring all sort of weather from severe elements to wintery mischief in the cold sector as the storm wraps up. The Euro long range weekly forecast that extends into the week 3 to 4 range is beginning to suggest a return to below normal temperatures and an active sub tropical jet/Southern tracking storm systems near the Christmas timeframe. Time will tell if those longer range ensemble guidance is correct.

GFS 12Z:

12052014 12Z hour 204 gfs_z500a_namer_34.png

12052014 12Z GFS hour 228 gfs_z500a_namer_36.png

Euro 12Z:

12052014 12Z Euro hour 216 ecmwf_z500a_namer_10.png

12052014 12Z Euro hour 240 ecmwf_z500a_namer_11.png

[Ptarmigan]

Even the coldest winters have warm periods courtesy of zonal upper air flow. I have seen it like in 1972-1973, 1976-1977, 1977-1978, and 1983-1984.

Is this an omen for what kind of weather we may have this winter?

Forecasts change. I'm going to try to enjoy each day and deal with whatever weather that we get.

Have a great day everyone!

Perhaps.........

[srainhoutx]

The GFS and Euro continue to advertise a powerful bowling ball 500mb upper 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.

12082014 00Z GFS 180 gfs_z500_vort_namer_31.png

12082014 00Z GFS 156 gfs_uv250_namer_27.png

12082014 00Z GFS 168 gfs_mslp_pwata_namer_29.png

12082014 00Z GFS 174 gfs_ir_namer_30.png

12082014 00Z Euro 192 ecmwf_z500a_namer_9.png

12082014 00Z Euro 192 ecmwf_T850a_namer_9.png

[srainhoutx]

There is still some spread within the ensemble mean via the Euro and GEFS. While there is some similarities to the November 21-22 event, the pattern is a bit different with less in the way of cold air. That said these pesky 5H lows tend to be a forecasting nightmare at this range and until the system nears California late week into the weekend as it enters the RAOB network, expect changes. It is noteworthy that this is likely the beginning of a very active parade of southern stream storms that will bring us into the Christmas/New Year timeframe with progressive colder air building in with each storm system. This +PDO/+PNA regime is going to be interesting to watch unfold.

12082014 12Z Euro Ensemble mean 168 get_legacy_plot-web249-20141208202509-9611-0789.gif

[Katdaddy]

A chilly morning across SE TX with temps in the 40s. Highs should approach the upper 60s under sunny skies this afternoon. Scattered rain chances return Wednesday afternoon through Friday morning with a series of disturbances. Next storm system to arrive early next week across TX.

[srainhoutx]

Morning briefing from Jeff:

A few days of mainly clear skies will give way to clouds and a slight chance of rain starting on Wednesday. Bigger weather maker possible by the weekend.

Surface high pressure over the region this morning is maintain a weak ENE to NE flow with widespread seasonal temperatures in the 40’s. Satellite images show a short wave disturbance over southern AZ moving eastward with an active sub-tropical jet stream and axis of mid and high level moisture extending from NE MX across Baja and into the Pacific Ocean. This disturbance and its associated mid and high level moisture will move eastward into TX over the next 24-36 hours. Overall trend is for the short wave to dampen or weaken with time. Lift and moisture may be just enough to produce a few spotty rain showers by late Wednesday into Thursday mainly west of I-45 otherwise this system will likely just increase cloud decks over the region. Increased clouds will help keep daytime highs a bit cooler on Wednesday and Thursday (low to mid 60’s) versus the near 70 today.

Strong storm system over the northern Pacific will move onshore the west coast via California late this week and across the SW US early this weekend. Global model guidance is having a difficult time with the track of this system and have been swinging widely between runs. For example the overnight guidance places the core of the upper air system some 300-500 miles north over yesterday morning. An upper air low looks to become cut off in the base of this trough and take on somewhat of a negative tilt orientation as it ejects out of the SW US into the plains. Questions are certainly there with respect to moisture return quality off the Gulf of Mexico. Latest GFS guidance only shows dewpoints in the mid 50’s by Sunday suggesting good quality moisture may be lacking especially for any strong to severe thunderstorms. For now will go with increasing warm air advection starting late Friday into Saturday with mainly just increased low level cloud decks. Will hold off rain chances until Sunday and hopefully models will come into better agreement over the next few days on the track of the upper air system and the resulting impacts across our region for late in this weekend.

[srainhoutx]

The tranquil pattern that we’ve been experiencing will begin to transition to a much stormier and eventually colder pattern as we head toward the Christmas Holidays and the end of the year. A series of southern tracking storm systems will arrive along the West Coast on Thursday and begin what appears to be a very active and stormy pattern across our Region. A very storm Pacific pattern with a powerful jet streak will usher in the change. Add to the mix a noisy sub tropical jet as well as storms crossing the Northern tier of States near the Polar jet and you have a recipe for a very unsettled pattern. The storm system over New Mexico this morning should bring cloudy skies and light showers as it cross the area. Tonight into Thursday.

This weekend a much stronger storm will move E across the Great Basin into the Southern Rockies as a long wave trough that has been offshore of the West Coast begins to slowly move inland. This long wave trough will eventually become established across the Inter Mountain West and the Plains next week with several fast moving storms taking a southern track across Northern Mexico, the Southern Rockies and the Southern Plains. It is expected that these southern storms will become rather persistent into the Christmas timeframe and beyond. There are growing indications that much colder air may begin to push across the North Pole into North America around Christmas into the New Year. Some of the longer range ensemble guidance is advertising below to much below temperature anomalies developing across much of North America as the pattern transitions to a more favorable pattern for delivering colder air well south across the Lower 48 into Mexico.

12102014 10Z 7 Day QPF p168i.gif

12102014 00Z CFS cfs-avg_z500a5d_namer_4.png

12102014 00Z CFS cfs-avg_T2ma5d_namer_5.png

[Ptarmigan]

Looks to be quite cold in all of North America by the time 2015 starts.

[vci_guy2003]

How cold.

[srainhoutx]

No changes in the general theme expected regarding our sensible weather well into the extended range. The Pacific will deliver a lot of southern tracking storms over the next couple of weeks and the sub tropical jet looks to remain rather noisy. That mean disturbances tracking E across the Southern tier of States will continue bringing chances of rain and snow across the higher elevations of the Southern Rockies and the potential for wrap around wintery mischief across the Southern Plains and the Panhandles of Texas and Oklahoma. This sort of pattern looks to continue right into the pre Christmas timeframe.

As we near Christmas and New Years Eve, the longer range Global ensembles remain steadfast suggesting a significant pattern change capable of delivery much colder air across much of N America. There are indications that the Southern jet and Polar Jet may merge bringing a very stormy and colder pattern across the Desert SW, New Mexico, Texas, Oklahoma, Arkansas, Louisiana, Missouri on E. Such a pattern has been expected and actually forecasted by most long range Winter Forecasters and it does look like those forecast are right on schedule. As always, there remains a lot of uncertainty and we cannot not accurately 'predict' the sensible weather beyond the 3-5 day range. That said the various teleconnection indices we look to are strongly suggesting we are well on our way to an interesting and active pattern as we end 2014 and begin 2015.

[BlueJay]

I'm all for "sensible weather"!

[srainhoutx]

Evening briefing from Jeff:

Fairly mild and tranquil pattern since before Thanksgiving will begin to undergo changes over the next 5-10 days.

Zonal upper air pattern of late will begin to undergo amplification as current “intense” western US storm system begins to buckle the upper air pattern. This system will move across the SW US on Friday and eject into the central plains late this weekend sending a Pacific cold front across TX. Main energy and dynamics will pass well north of SE TX, but combination of increasing moisture and incoming cold front will likely result in a round of showers and thunderstorms from midday Sunday into midday Monday. Not looking at severe weather with best dynamics northward toward OK. Will have to watch for winds shifting to the SW in the mid levels which can dry slot this area and really cut back on rainfall potential. Given the best forcing will be well to the north, only expecting modest rainfall amounts of generally less than an inch. This is also a classic case of where the best rain chances tend to be across the northern portions of the region.

Of bigger interest is the apparent change in the storm track following this first “ lead” storm. Southern branch jet stream appears to become the increasingly dominant weather maker leading up toward Christmas and even into early 2015. A secondary storm system will follow the first “late weekend” storm by the mid to end of next week and likely progress much further southward yielding a more active weather event for TX. Additionally, long range model guidance with support from their ensemble means indicate cold air will make a return into the US near/just before Christmas with an active southern storm track continuing. Would like to see a little more support for this pattern change before jumping fully on board with a colder and wetter regime starting next week and lasting into early January 2015, but this would be supported by warm phase ENSO (El Nino) conditions in the Pacific. While current water temperatures in the Nino regions are near or above the required thresholds, other indicators are still not fully suggesting El Nino conditions. There remains a 65% chance of El Nino conditions early in 2015 and while “official” warm phase ENSO may not be in place, the atmospheric response appears to be favoring what one would likely see in such a warm phase.

[srainhoutx]

As Jeff alluded to late yesterday evening, the Global ensembles are in rather good agreement with the expected pattern change around the 20th of December. The ensembles are indicating a very active Southern Storm track with each storm assisting in buckling the jet stream pattern across North America that would tend to suggest that the stormy and progressively colder weather would develop across the Desert SW, Southern Rockies into the Southern Plains and on East. The longer range ensembles develop a West Coast Ridge easing the parade of storms currently affecting the W Coast but allow disturbances in the Eastern Pacific to track across Mexico, Texas and the Gulf Coast States before turning NE. The Polar jet should have embedded disturbances dropping S out of Canada and snow looks to begin building across the Plains lending to less and less airmass modification. This is a typical weak El Nino pattern and it appears we are well on the way to witnessing a big pattern shift that will bring a very active period that will last into the New Year. Below are the 500mb anomalies, or the smoothed jet stream flow pattern expect...

CFS Mean:

12122014 00Z CFS 360 cfs-avg_z500a5d_namer_3.png

12122014 00Z CFS 480 cfs-avg_z500a5d_namer_4.png

12122014 00Z CFS 600 cfs-avg_z500a5d_namer_5.png

Euro Ensemble Mean:

12122014 00Z Euro Mean 240 ecmwf-ens_z500a_namer_11.png

GEFS Mean

12122014 06Z GEFS 240 gfs-ens_z500a_namer_41.png

12122014 06Z GEFS 330 gfs-ens_z500a_namer_56.png

Canadian Ensemble Mean:

12122014 00Z GEM 240 gem-ens_z500a_namer_41.png

12122014 00Z GEM 330 gem-ens_z500a_namer_56.png

[srainhoutx]

The over night ensembles continue to advertise an active Southern storm track with a strong storm signal late this week tracking across N Mexico into Texas and the Southern Plains. This storm looks to begin the process of ushering in a signicant pattern change that continues into the Christmas Holiday period.

The longer range guidance is suggesting the possibility of a NW Gulf Coastal low developing around the 24th +/- a day or two ushering much colder temperatures and additional Southern tracking storms as the polar jet buckles rather far S and a + PDO/+PNA/-EPO/-AO regime develops. The time frame into New Year looks cold and stormy from the Great Basin into the Plains. This sort of pattern change looks to be rather similar to what we witnessed in mid November except possibly colder and stormier as we enter the coldest time of Winter climatology wise for our Region.

[cperk]

Bring it on,i'm ready for some winter weather.