I think there would be some snow in the Houston area if the 0z or 6z GFS verified, just by glancing at the forecasted temperatures and thickness values. That map is very low res and uses some "unique" algorithm that isn't official nor is it accurate...wxdata wrote:0z GFS keeping any snowfall well north of here.
Most likely because the GFS has just recently switched around to this wintry solution. And, while the Euro has been hinting at this for several runs, it has now switched back to the warm and dry 12z GFS solution of yesterday. There is mucho model disagreement going on right now, so the forecast for next week, as HGX stated, is very low confidence.snowman65 wrote:Why aren't any local mets talking??? No forecast anywhere is even hinting about this........
If one were to extrapolate the 0z or 6z NAM beyond its 84 hour time frame, it looks to me like the model would favor the GFS more than the Euro. You can see the piece of energy on the NAM already beginning to dig into the SW, while the Euro at the same time shows a much flatter solution and holds the energy back in the Pacific.srainhoutx wrote:We will need to keep an eye on the Pacific NW as well as the W Coast this weekend as the system approaches. The concern has been that the Upper Air Pattern may under cut the W Canadian Ridge and create a more zonal type flow (warmer). While the GFS has certainly trended in the right direction to a wintry pattern, the EC and GGEM have now switched places with the GFS. It is almost time frame where the NAM can start 'sniffing' a pattern that will lend to a sensible weather solution. Also, let's see how strong the feature is this weekend. That will likely give us some big hints as to what we can expect.
00Z GFS Ensemble Members...PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
855 AM EST FRI FEB 19 2010
VALID 12Z TUE FEB 23 2010 - 12Z FRI FEB 26 2010
UPDATED PRELIM PROGS MADE ONLY COSMETIC CHANGES TO THE EARLY
RELEASE. A STRONG BLOCKING 500MB PATTERN AT HIGH
LATITUDES...FEATURING HIGHS OVER WRN CANADA AND THE DAVIS
STRAIT...WILL SLOWLY BEGIN TO WEAKEN OVER WRN NOAM WHILE THE DAVIS
STRAIT BLOCK HOLDS THRU THE END OF THE MEDIUM RANGE PERIOD. WHILE
THERE IS DECENT AGREEMENT ON THE DAY 3 SYS AFFECTING THE OH
VLY/MID ATLANTIC...UNCERTAINTY INCREASES DRAMATICALLY FOR THU/FRI
DAYS 6-7. ENSEMBLE SPAGHETTI PLOTS SUGGEST THAT THE DETERMINISTIC
00Z/19 ECMWF/CANADIAN SOLUTIONS...WHICH SHOW SIGNIFICANT ENERGY
OVER THE SWRN CONUS FOR THU DAY 6....ARE OPPOSED TO THE GFS/UKMET
FAMILY OF SOLUTIONS. THE GFS/UKMET FAMILY OF SOLUTIONS HAS THE
MAIN SRN STREAM SYS CROSSING THE GULF COAST STATES THU....MORE IN
LINE WITH YESTERDAYS ECMWF RUNS...AND PLAYS UP ENERGY DROPPING S
OUT OF A NRN CANADIAN VORTEX. THIS SUGGESTS POSSIBLE PARTIAL
PHASING OF THE SRN STREAM IMPULSE WITH THE NRN STREAM LATER
THU/FRI. THE GFS/UKMET FAMILY OF SOLUTIONS AND ENSEMBLE MEAN
CHARTS FAVORS NRN STREAM DOMINANCE FOR THU/FRI DAYS 6-7...AND
PLACE SOME KIND OF DEEPENING LOW PRES OFF THE MID ATLANTIC OR NEW
ENG COASTS. A MORE PERFECT PHASING OF NRN AND SRN STREAMS WOULD
ALLOW LOW PRES TO DEEPEN FARTHER DOWN THE COAST OFFSHORE...WITH
THE DISTANCE OF THE TRACK OFFSHORE A CRITICAL FACTOR.
A SLIGHTLY RETROGRESSIVE POSITIVE ANOMALY MOVING FROM THE DAVIS
STRAIT INTO NORTHEAST CANADA FAVORS A QUASI-STATIONARY CYCLONE
NEAR THE NORTHEAST...WHICH SHOULD KEEP NEW ENGLAND WET/SNOWY FROM
TUESDAY ONWARD. ANOTHER DEEP CYCLONE IS EXPECTED TO REMAIN
OFFSHORE THE PACIFIC NORTHWEST THROUGH THE MEDIUM RANGE PERIOD.
THE MODELS AGREE ON THESE IDEAS...THOUGH THERE ARE DETAIL ISSUES.
A COMPROMISE/BLEND OF THE 00Z GFS/00Z ECMWF SUFFICED THROUGH
WEDNESDAY NIGHT...BEFORE THE 00Z ECMWF DIVERGED FROM THE ENSEMBLE
ENVELOPE THEREAFTER WITH THE LOWS NEAR NEW ENGLAND AND OFFSHORE
THE PACIFIC NORTHWEST. FROM THURSDAY MORNING ONWARD...USED A
COMPROMISE OF THE 00Z GFS/00Z GEFS MEAN...WHICH MAINTAINED
REASONABLE CONTINUITY. LAKE EFFECT SNOWS ARE EXPECTED FROM
WEDNESDAY ONWARD IN THE CYCLONIC FLOW ON THE BACKSIDE OF THE
NORTHEASTERN VORTEX...WHILE PACIFIC COLD FRONTS WEAKENING AS THEY
APPROACH THE PACIFIC NORTHWEST SHOULD BRING LIGHT TO MODERATE
RAINS/ELEVATED SNOWS INTO THE REGION. THE MAIN THEME OF THIS
WINTER PERSISTS...WITH COLDER THAN NORMAL TEMPERATURES EXPECTED
EAST OF THE ROCKIES AND MILD TO WARM TEMPERATURES EXPECTED ACROSS
CALIFORNIA AND THE SOUTHWEST.
ROTH/FLOOD
After a warming trend this weekend…it will return to cold next week.
Big differences continue in the extended with wide varying forecast solutions between liquid and frozen.
Discussion:
Will tackle the near term issues first and then make some attempt at next week although the theme is very low confidence and the sad fact that any forecast for next week at this point is bound to be wrong to some degree.
Upper level short wave tracking over S TX and the NW Gulf this morning with light to moderate rains from Galveston Island to Victoria and southward. Looking at radar rainfall estimates shows some decent amounts around Matagorda Bay, but ALERT data from LNRA suggests otherwise with max totals noted so far of .16 of an inch at Lake Texanna. Radar is likely overestimating rainfall in this area although a few locations may total up to .5 of an inch this morning from Port Lavaca to Palacios southward. This short wave will be east of the area by late afternoon with all rainfall ending and pushing eastward. Low level warm air advection will continue with no air mass change with this feature. Dewpoints slowly rise toward the mid 50’s overnight and a few models are showing a strong sea fog event. Feel dewpoints will not greatly exceed nearshore water temps. Tonight so sea fog should not be extensive. Warm air advection increases on Saturday with dewpoints rising toward 60. May see a few showers develop with the increasing moisture regime and by this time dewpoints will likely exceed nearshore water temps. Leading to sea fog. Will likely sock in the nearshore waters and bays during the day on Saturday and then spread the thick soup inland Saturday night…although not sure how far inland the fog makes it. Highs will reach 70 on Saturday and the lower 70’s on Sunday.
Sunday still looks to be stormy ahead of the next strong cold front. As suspected yesterday, capping to the SW over the CRP/VCT area may encompass more of SE TX than the models are showing especially since boundary layer winds turn SW ahead of the pre-frontal trough…usually an unfavorable convective profile for SE TX. However models are in decent agreement that the air mass will become increasingly unstable during the day with showers and thunderstorms developing in the warm sector ahead of the pre-frontal trough and along the trough itself. Will put the best chances along and E of I-45 with this area showing the greatest severe threat. Will need to watch trends Saturday and early Sunday as this threat could be expanded as the event draws nearer. Also as mentioned yesterday, the models are likely a little aggressive on the amount of instability with this system, so any severe weather should be isolated.
Next week:
The problems begin with the passage of the strong old front Sunday evening with the GFS now much colder and wetter for early next week and the past consistent ECMWF having flipped 180 from yesterday morning on its 00Z run to a much drier and warmer forecast with the GFS flipping 180 the other way…go figure! UKMET remains stable and in support of the colder/wetter solution along with several of the ensemble members. The problems with the models appear to be in their handling of the energy coming into the US west coast and the developing split flow aloft.
With all this on the table and considering up until last evening the ECMWF was favorable for wet and cold…with trend in that direction and wait for the 12Z runs this morning to go flip flopping all around…reminds me of hurricane season! Following the colder/wetter solution brings rain back into the forecast rapidly by late Monday-Wed of next week. GFS forecast soundings and critical thickness values support P-type issues across much of TX if in fact this event pans out. I am more confident on cutting temperatures than adding frozen precipitation to the forecast. For now will go with highs in the 50’s Monday and then the 40’s Tuesday and Wednesday and they may need to be knocked down even more into the 30’s for Tues/Wed. As for precipitation, will bring rain into the picture overnight Monday and keep it all liquid into Tuesday and then bring RA/SN mix into our NW counties Tuesday afternoon. If the GFS is in fact on the right page and the ECMWF trends back toward its older solutions then RA/SN mix will be pushed southward and all SN will be possible over portions of the area with some accumulations. Needless to say yet again…the forecast for next week is extremely low confidence.
I have to disagree.. No one needs to forecast it yet, but it is worthy of a mention of a possibility. The fact is, we don't know yet. So to say nothing at all is a forecast in itself.wxman57 wrote:I certainly wouldn't mention or forecast snow for Houston based on what I'm seeing in the models. There's little or no agreement in the models and almost no consistency from run-to-run.. The GFS has a moderate disturbance moving across Texas on Tuesday while the Euro shows a very weak shortwave with little or no precip. The Euro has a much more significant system passing on Thursday but the GFS shows just about nothing next Thursday. Remember that a week ago the models were forecasting the BIG EVENT would be today. I don't see any big event out my window.
The only things I'm somewhat confident in is that a couple of disturbances will move across Texas next week, giving us a good chance of some cold rain. I'm not trusting any of the models beyond that at this time. Give it another couple of days and let's see if there's any run-to-run consistency and we can see what kind of airmass overhead we'll be dealing with.
Here's a GFS 06Z meteogram for Houston (IAH). It does show some cold rain Tuesday changing to sleet/snow Tuesday night, but I'm not buying it for the reasons I mentioned above.
Who needs to mention it? We have mentioned the slight possibility of winter weather in Texas in this thread. But there are too many uncertainties to say one thing is more likely to happen than another. If you're saying that the NWS should mention it in the Houston zone forecasts then I'd disagree. Way too much uncertainty for such an extreme event. They may talk about it in their AFD, a text read by no one except weather enthusiasts and other meteorologists. But they're not going to mention it in a zone forecast.biggerbyte wrote: I have to disagree.. No one needs to forecast it yet, but it is worthy of a mention of a possibility. The fact is, we don't know yet. So to say nothing at all is a forecast in itself.
Especially with not one model showing any consistency right now with next week (except maybe for the UKMET), I agree with this!wxman57 wrote: Who needs to mention it? We have mentioned the slight possibility of winter weather in Texas in this thread. But there are too many uncertainties to say one thing is more likely to happen than another. If you're saying that the NWS should mention it in the Houston zone forecasts then I'd disagree. Way too much uncertainty for such an extreme event. They may talk about it in their AFD, a text read by no one except weather enthusiasts and other meteorologists. But they're not going to mention it in a zone forecast.
Yeah, 12z partially in. Shows a MUCH deeper system than 00Z Euro for Tue-Wed over Texas. Still shows temps above freezing here for the most part, though. I'll make a meteogram when the model is fully in. Will also make a 12Z sounding forecast to look at the temps aloft. Even if temps at the surface are forecast to be above freezing, if temps aloft are cold enough then we could get frozen precip.Mr. T wrote:Thankfully, the 12z GFS still looks the same as the 0z and 6z runs...
It's time for the Euro to jump back on board!
I agree, but at least the trend of the GFS is getting a bit better. The supressed solution appears to be taking shape at this time anyway. Portastorm must be a tad excited in Austin right now.wxman57 wrote:Yeah, 12z partially in. Shows a MUCH deeper system than 00Z Euro for Tue-Wed over Texas. Still shows temps above freezing here for the most part, though. I'll make a meteogram when the model is fully in. Will also make a 12Z sounding forecast to look at the temps aloft. Even if temps at the surface are forecast to be above freezing, if temps aloft are cold enough then we could get frozen precip.Mr. T wrote:Thankfully, the 12z GFS still looks the same as the 0z and 6z runs...
It's time for the Euro to jump back on board!
I'm still not sold on this GFS solution, though. I want to see more run-to-run consistency and agreement with other models first (like the Euro).
