December 2014: New Year's Eve Wintry Mix Possible

[ticka1]

will our winter temps continue with any hint of frozen precpation?

[snowman65]

I don't see anything even remotely resembling winter anytime soon....

[srainhoutx]

The time frames to watch are December 4th-7th as a Southern Storm tracks across our Region and ushers in a wet period and a shot of cold air. This may be a precursor of a bigger surge of Arctic cold around the 10th -14th. The Arctic Oscillation and Eastern Pacific Oscillation look to begin to go negative to strongly negative while a Western Pacific Ridge builds N into Alaska and a positive Pacific North American teleconnection pattern redevelops. There is also a significant warming of the Stratosphere occurring over Siberia and Eurasia. We witnessed this warming occurring back in October before Typhoon Nuri transitioned to extra tropical near the Bering Sea/Aleutian Islands and transitioned the entire pattern that brought us our Arctic outbreak on November 11th to 18th. Our source regions are getting mighty cold and snow cover is increasing across Canada. We will see.

[sambucol]

The time frames to watch are December 4th-7th as a Southern Storm tracks across our Region and ushers in a wet period and a shot of cold air. This may be a precursor of a bigger surge of Arctic cold around the 10th -14th. The Arctic Oscillation and Eastern Pacific Oscillation look to begin to go negative to strongly negative while a Western Pacific Ridge builds N into Alaska and a positive Pacific North American teleconnection pattern redevelops. There is also a significant warming of the Stratosphere occurring over Siberia and Eurasia. We witnessed this warming occurring back in October before Typhoon Nuri transitioned to extra tropical near the Bering Sea/Aleutian Islands and transitioned the entire pattern that brought us our Arctic outbreak on November 11th to 18th. Our source regions are getting mighty cold and snow cover is increasing across Canada. We will see.

Thanks for posting this great news! Bring on the cold

[srainhoutx]

It looks like El Nino is progressing nicely and the Day 6 to 7 Quantitative Precipitation Forecast (QPF) certainly suggests a pattern we would expected as an El Nino pattern develops. The West Coast has endured a multi year significant drought and it appears the active Pacific will bring heavy higher elevation snow and lower elevation heavy rainfall beginning Sunday into Tuesday. Our rain chances should increase across our Region next week as the Pacific storm moves inland and the return flow of the Gulf becomes established with a noisy sub tropical jet overhead. We may see a rather damp first week of December.

[Ptarmigan]

It looks like El Nino is progressing nicely and the Day 6 to 7 Quantitative Precipitation Forecast (QPF) certainly suggests a pattern we would expected as an El Nino pattern develops. The West Coast has endured a multi year significant drought and it appears the active Pacific will bring heavy higher elevation snow and lower elevation heavy rainfall beginning Sunday into Tuesday. Our rain chances should increase across our Region next week as the Pacific storm moves inland and the return flow of the Gulf becomes established with a noisy sub tropical jet overhead. We may see a rather damp first week of December.

11252014 08Z Day 6 to 7 QPF 97ep48iwbg_fill.gif

The West Coast could use that rain. I would be just as happy if they got the rain. They need it.

[srainhoutx]

The guidance continues to advertise a significant pattern change that would bring heavy precipitation across California/Oregon and Washington into the Great Basin as we start December. As Pacific moisture streams inland, a couple of shortwaves (upper air disturbances) will cross the Northern tier of the Nation as well as Canada ushering in a couple of shots of modified colder air.

The longer range teleconnection indices are trending to a more favorable pattern of delivering a strong Arctic airmass S from Canada as a very strong Ridge develops along the NE Pacific into Alaska. If the longer range ensemble guidance is correct, a deep trough with carve out across the Central United States across the Inter Mountain West and Plains with embedded storms tracking across Mexico and the Southern Plains. This would favor a return to a much colder pattern across our Region around December 12th, +/- a couple of days and may bring significantly colder air that is pooling across the Arctic and our source Regions of Western Canada well S possibly into Mexico, Texas, Louisiana and Oklahoma. We will see.

[srainhoutx]

The 12Z Parallel GFS continues to advertise a big pattern change beyond the Medium Range into the extended Range. There continues to be significant warming of the stratosphere across Eurasia and Siberia that appears to be stronger than the event in October across the areas mentioned that assisted with ushering in the Arctic Outbreak of mid November. It will be interesting to see if the trends continue as we begin December and head into the mid December timeframe.

[srainhoutx]

The global models are suggesting that the Pacific will be the dominate driver of our weather pattern across North America as December begins. There is a quick shot of cold air arriving on Monday as a 1040+ High Pressure cell drops into the Northern Plains and quickly moves E. The cold front may provide some light rain as it drops S across the Plains on Sunday into Monday. Temperatures moderate quickly with the fast zonal flow across the US and another front looks to arrive later next week that may provide a better chance for rain as the Gulf opens up and moisture returns across our Region.

The teleconnection indices continue to suggest a +PDO/+PNA/-AO regime will develop near mid December, but lacks a bit of blocking across the NE Atlantic meaning any cold weather cannot become established across the Central US. Temperatures do not look to far from normal the Pacific pattern driving the sensible weather as mid December nears.

[srainhoutx]

The overnight guidance is come into agreement that a sharp modified Arctic cold front will arrive on Monday ushering in a big cool down once again albeit fairly short lived. The fly in the ointment is whether we will clear out after the front passes and will there be a chance of light rain/drizzle as upglide develops behind the front. The Arctic High pressure is relative strong in the 1044mb range and will enter the Northern Plains Sunday evening. With the lack of snow cover across the Plains, airmass modification will occur, but it is cold across Canada with temperatures running anywhere from 0F to -20F. The coldest air will be to our N and E and will quickly move E as a zonal flow becomes established.

Meanwhile a strong storm system is nearing the Pacific Coast and will bring abundant rain and higher elevation snow across the West into the Great Basin. A true sign that El Nino is becoming more likely as we head further into Winter.

[Ptarmigan]

The overnight guidance is come into agreement that a sharp modified Arctic cold front will arrive on Monday ushering in a big cool down once again albeit fairly short lived. The fly in the ointment is whether we will clear out after the front passes and will there be a chance of light rain/drizzle as upglide develops behind the front. The Arctic High pressure is relative strong in the 1044mb range and will enter the Northern Plains Sunday evening. With the lack of snow cover across the Plains, airmass modification will occur, but it is cold across Canada with temperatures running anywhere from 0F to -20F. The coldest air will be to our N and E and will quickly move E as a zonal flow becomes established.

Meanwhile a strong storm system is nearing the Pacific Coast and will bring abundant rain and higher elevation snow across the West into the Great Basin. A true sign that El Nino is becoming more likely as we head further into Winter.

http://weather.unisys.com/satellite/sat ... oop-12.gif

I can see so many low pressure systems in that satellite over the Pacific. Nice to see the Western US getting rain as they could use all of it.

[srainhoutx]

As we get closer to December, the big long lasting warm up is loosing its legs. The 12Z parallel and old GFS are sniffing several shots of cold air in the medium range, but they are transient. What is intriguing is the tropical forcing developing as a WPAC Typhoon wraps up and the Aleutian low increases in strength which is very common in a +PDO regime. The PNA is still expected to turn strongly positive while the AO drops back into negative territory around the 8th to 10th of December. The GEM is also onboard with this sort of solution. If an amplified MJO pulse develops and swings back into the Western Hemisphere, look for a digging trough across the Inter Mountain West once again and if the NAO becomes negative, a stout blocking regime could develop. There are a lot of moving parts across the Northern Hemisphere right now and add a SSW event into the mix, we may see a stormy and cold later half of December into January. We will see.

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[srainhoutx]

Folks across N Texas mainly north of the Metroplex need to keep on eye out for some light freezing drizzle Monday afternoon into early Tuesday. Travel issues do not look like a big concern, but light icing on metal surfaces and trees may be possible. Ground temperatures are just too warm for any elevated bridge issues as of right now. Light icing may spread further E toward Texarkana early Tuesday as the sharp/shallow very cold airmass allows over running moisture to develop with the up glide. Stay warm. This quick hitting shot of cold air will feel much different than the upper 70's to low 80's we've been experiencing.

[srainhoutx]

The global guidance continues to advertise a changeable pattern in the medium to longer range as we head deeper into December. After our quick cool down Monday night into Tuesday, foggy continues look to be the theme as the sharp Arctic front retreats N rather quickly in the zonal flow off the Pacific. There are indications that another storm system may develop in the Southern jet stream later this week into next weekend as the southern branch system has more energy associated with it than the northern branch due to the fast zonal flow and the coldest air remains bottled up N of the US border.

The fly in the ointment in the longer range will be what becomes of a developing tropical cyclone in the Western Pacific (95W) near New Guinea. It is important to understand that what happens halfway around the world does have an effect on our sensible weather across North America. The Global models are suggesting a powerful Typhoon will develop and skirt near the Philippines and eventual recurve into a powerful cold upper low near the Aleutian Islands and Bering Sea in about 10-12 days. Such a pattern developed with Super Typhoon Nuri as you recall back in early November that reshuffled the entire planetary weather pattern across the Northern Hemisphere and brought our record breaking cold outbreak mid-November. It is also noteworthy that the global models are suggesting the cold pool of water across the Northern Pacific (PDO) will continue to be strongly positive. We have not witnessed a strongly +PDO for many years, so that suggests the colder stormier weather is very possible along and E of the Continental Divide. Other teleconnection indices we monitor are trending toward a pattern that is very capable of delivery cold air very far south. In fact, if the –EPO (East Pacific Oscillation), + PNA (Pacific-North American Pattern) and a – AO (Arctic Oscillation) coincide with a –NAO (North Atlantic Oscillation), then it is very possible the coldest air of the Winter Season may arrive before Christmas. It is also noteworthy that the sub-tropical jet appears to remain very noisy allowing for mid/upper level tropical moisture to stream over any cold airmass at the surface that may be in place later in the month. Typically we need to monitor for areas of low pressure in the upper levels that track across Northern Mexico into the Southern Rockies and the Southern Plains. It is always a wildcard to forecast any surface lows spinning up along the NW Gulf Coast, but usually we see such a pattern in Winter where coastal waves of low pressure develop and sometimes deepen into rather strong Coastal Lows as they move N and E toward the Atlantic. In closing the pattern looks rather volatile, so expect changes as we enter the month of December and deeper into Winter during January.

[dljones33]

So what time will the rain move in tomorrow? I need to fertilize my lawn before it hits!

[srainhoutx]

So what time will the rain move in tomorrow? I need to fertilize my lawn before it hits!

I don't see more than just light showers and perhaps a skinny line of light rain before noon tomorrow. Perhaps some drizzle behind the front which is moving quicker than expected by the way. Tomorrow we will need jackets before sunset as temperatures quickly fall a good 20 to 25 degrees after the front passes. We will be a good 30 to 35 degrees colder by tomorrow night.

[Katdaddy]

Back to work after the Thanksgiving holiday. Dense fog being reported across portions of SE TX with light rain showers moving inland along the Upper TX Coast. Cold front near Waco should move across Houston metro around noon. It has slowed a little which may allow upper 70s to be reached SE of U-59. The front moves off the Upper TX Coast later this afternoon or early evening. A few isolate thunderstorms may be possible. Tuesday will be a cloudy cool day with lows in the 40s and highs 50s. Temps begin to slowly warm into the 60s and 70s later in the week however clouds and periods of drizzle and light rain will remain thanks to a plume of Pacific moisture.

[snowman65]

This one looks to be like one of those fronts you don't even notice. Strange weather pattern so far this fall/winter. One good teaser front then back to typical S.E Tx weather (or warmer) for this time of year....IMO

[srainhoutx]

Morning briefing from Jeff:

Big changes on the way today as a strong cold front moves across the area.

Arctic boundary located along a line from Del Rio to Georgetown at 700am. Temperatures across this boundary show at least a 20 degree drop in an hour or so. College Station is currently 63 and Waco 41 (wind chill of 32). Cold front will advance across SE TX today with rapidly falling temperatures and increasing north winds. Radar shows showers along the coast this morning attempting to spread inland and HRRR short term model shows some additional development especially along US 59 and toward the coast late this morning/afternoon as the shallow arctic boundary moves through. Cold front should reach College Station between 800-900am and metro Houston 1100-noon and then off the coast in the 300-400pm period.

Fairly messy week on tap as arctic front stalls in the nearshore waters late tonight and upglide of warm air over the surface cold dome establishes. This will result in a period of cold and damp conditions on Tuesday with light drizzle, fog, and thick cloud cover preventing much if any temperature recovery. Expect temperatures to remain nearly steady in the 40’s to low 50’s on Tuesday.

Forecast becomes more uncertain on Wednesday with the main question being when does the arctic boundary lift northward as a warm front with warm and muggy conditions returning. I will trend toward the slower northward progression of the boundary with thick cloud cover north of the front helping to mitigate the warming. Upglide will continue and expect light drizzle and foggy conditions into Wednesday. Temperatures will start to slowly rise on Tuesday evening and continue on Wednesday with highs likely back into the 70’s by Thursday.

Warm front should return northward late Wednesday into Thursday with dewpoints recovering into the 60’s. Abundant mid and high level moisture will stream into the region from the Pacific while low level moisture increases at the surface yielding a cloudy and at times wet forecast Thursday-next weekend. Hard to time short waves in the SW flow aloft will determine when the best rain chances will be indicated. Temperatures will return to above normal values for early December as southerly low level flow is established. Will need to keep an eye on potential for near shore/ bays sea fog by Friday as dewpoints rise above the “chilled” waters near the coast.

[BlueJay]

The sky has opened up. We are currently enjoying a healthy rain shower. Already reporting 0.04 inches!