South Lake Tahoe Weather Update-2/5/09
The snow is back! The Lake Tahoe basin is seeing significant snow this morning with road controls up and the resorts receiving fresh powder with more on the way. The storm door appears to be wide open albeit with no huge storms on the horizon but the number of impulses should build the snow pack in small increments. The forecast calls for 6-12 inches on new snow through Saturday morning before another storm from the Gulf of Alaska moves into the region. This storm appears to be much colder and with ample moisture in place Lake Tahoe may see another round of significant snow Sunday night through Monday. Looking ahead into next week and the big Presidents weekend midweek looks snowy and after that the models get murky. My gut feeling is that there will be snow over the big weekend because we are in a very progressive pattern with impulses moving off the Pacific every 36-48 hours or so. Keep you fingers crossed and thank for burning the old skis and boards! Maybe we really do have another shot at winter!
The weather remains tranquil and warm for early February but changes may be on the horizon. Long range models show a pattern change beginning late in the week and precipitation in the form of low elevation rain and high elevation snow may fall beginning in earnest next weekend. Beyond the next seven days all bets are off but this much is certain-there will be a change from the current stagnant and very dry conditions. Enjoy the beautiful weather now and hope for new snow for the big Presidents Day weekend!
Model GFS Weather Map 2/6/09
Ok. I know I was pessimistic in the last post for Lake Tahoe weather but things may be changing for the better ( if you like weather) a bit sooner than even the models were indicating yesterday. For some reason the ensemble weather models are all showing some sort of low dropping out of the Gulf of Alaska and forming a cutoff low off the California coast early to mid next week. How much precipitation this brings to the Lake Tahoe region remains to be seen but at least the models are now in complete disarray over what will be happening and NOT holding the persistent north Pacific high in place for much longer. This is good news if you want to see a major pattern shift! I know many of you will be traveling to Lake Tahoe this month and especially over the big Presidents weekend so I will try and up-date this post on a daily level from here on out through late March or early April. It does appear and this is tough 14 days out that it may be an active pattern during the Presidents weekend. Make sure you stay tuned to weather before driving up to your South Lake Tahoe Vacation Rental.
Map for Mid-Week Early February
Lake Tahoe Snow!
Finally it looks like we have a couple of decent storms brewing in the Pacific which may affect the Lake Tahoe basin and the High Sierra. At 6500 feet (my home) it is currently raining with a mix of heavy wet snow but it is snowing at the resorts and we should see 4-6 inches today through early tomorrow. Then a much more potent system appears to be forming and will possibly bring significant snow Friday night into Saturday mid-day. How much will fall from this system is in question but after each model run it looks more and more impressive! Right on the heels of that storm is another which may be much colder and more impressive dumping possibly 1-2 feet of snow at the resorts and 10-14 inches at lake level. This event could last from Sunday- Tuesday. It then looks like Lake Tahoe will dry out but the active pattern should continue through the next 15 days with the most impressive storms looking like day 10-15 on the extended. Stay tuned!
Here is the NWS forecast statement for 1/22/09:
Area forecast discussion
National Weather Service Reno Nevada
350 am PST Thursday Jan 22 2009
a relatively narrow but heavy band of rain is moving slowly across
northern and central California this morning as an upper trough makes its
way onshore. This band of heavy precipitation is being fed by a juicy
subtropical connection off the Baja California coast. Snow levels are currently
around 8500 feet or so...which is pretty normal for this type of
subtropical tap. Only the highest mountains in our area will
see any snowfall with this storm...and even then it should be pretty
wet and heavy. Snow levels are expected to remain high...generally
above 8000 feet through Friday...before finally coming down by
Friday night as we get into some colder air. No winter statements
expected at this time...due to the high snow levels.
The elongated trough coming into California this morning has split into two
main vorticity maxima...with the shortwave currently northwest of the Bay
area being the one of our concern. This wave will lift through
northern California and into the far northwest corner of Nevada by this evening.
As this wave pushes inland...the stream of heavy precipitation we are
seeing on the cal radars will push east across the higher elevations
through the day and scattered showers across western Nevada.
There is some good diffluence aloft lifting the deep moisture... and
models are indicating a band of 700mb frontogenesis from Truckee to
Lovelock later this afternoon and evening. This low level forcing
will create a nice band of showers across the Interstate 80
corridor...with periods of moderate to heavy rain possible. Both GFS
and European model (ecmwf) indicating this band of heavier precipitation setting up across the
forecast area...so bumped up probability of precipitation and quantitative precipitation forecast for this afternoon and
evening in the western Nevada valleys.
Late tonight and into early Sat morning we will see a Little Break
in the action as we get some weak shortwave ridging...but with the
abundant moisture still streaming off the Pacific and into our
area...scattered showers are not out of the question.
By Friday...another upper level low will drop in right behind...with
the nose of a 100kt jet pushing across central California and into the
Sierra. On top of that...a very nice looking diffluent left exit
region will setup right over the Tahoe area. Latest models are
coming up with some impressive quantitative precipitation forecast values for the time period
between Friday night and early Sat morning as we get a shortwave
lifting through norcal...interacting with the dynamic jet. This is
plausible to happen with this deep subtropical moisture tap setup.
So...upped up quantitative precipitation forecast and probability of precipitation for Friday night and Sat as we get this jet
maximum moving into our area. If models continue to show this period of
enhanced precipitation...the forecast may need to go up even more. By
Friday night...snow levels will begin to lower from 8000 feet down
to near lake level by early Saturday morning...which could cause
some travel concerns for the Sierra passes Friday night and
Long term...Sunday through Wednesday...
models continue to drop energy down along the West Coast for Sunday
and Monday developing a deep positively tilted trough/closed low from
the northern rockies back across California. The GFS...Canadian...
and ec continue to differ in details with respect to location of the
upper low and timing.
Generally for Sunday and Sunday night the upper low should extend
across northern California with the GFS further west...rotating the low
system off the coast... and the ec inland. At any rate snow will
increase across the Sierra Sunday and continue through Monday. By
Tuesday models cut this deep low off from the northerly branch of
the jet sagging the primary feature west of Southern California. This would
decrease precipitation across the Sierra Tuesday to scattered
showers. By Wednesday although again the details differ...northern
California and western Nevada should be under northerly flow aloft as the system
Overall expect snow in the Sierra Sunday diminishing to scattered
showers by Tuesday with Wednesday and later in the week generally
dry. Snow levels will start out around 5000 feet so Sierra
precipitation should be all snow. Over the period from Sunday
through Monday night there could be 6 to 10 inches or so of snow at
lake level with a foot or 2 at higher elevations of the Sierra. Will
have to keep an eye on storm organization to determine whether any
watches or warnings will be needed. At this time it looks like the
best chance for heavier snow would be Sunday associated with the
cold front...with generally light snow for the the remainder of the
early week period.
For western Nevada valleys...snow levels will start at around 4000
feet up toward the Oregon border to 5200 feet or so in the
Reno-Carson areas to 5500 feet further east. The best chance for
valley snow will be associated with the cold front passage. The ec
drops the cold front through western Nevada late Sunday and Sunday
night. The GFS brings it through a little earlier...Sunday afternoon
and early Sunday night. Except for Surprise Valley would not expect
more than a dusting to an inch or less for the valleys.
The coldest day of the week should be Monday but temperatures will
just be 5-10 degrees below normal in most areas before moderating
back close to normal later in the week. Jah
Lake Tahoe Snow Conditions-Reports
The skiing and riding at Lake Tahoe should improve later in the week as the weather pattern changes for Lake Tahoe and the High Sierra. It appears that there may be 6-12 inches of new snow between Wednesday and Thursday and more over the weekend. Looking out into the future the weather pattern appears to stay active. What is really needed is a big dump of wet snow tapering off to a top base of dry fluffy snow. Here are the current resort reports for January 20, 2009:
Here is the model map for February 1, 2009:
The following is the Scientific forecast discussion for the next several days from the NWS:
Area forecast discussion
National Weather Service Reno Nevada
323 am PST Tuesday Jan 20 2009
the persistent upper level ridge over the western states will
finally get pushed east by Wednesday as we get into a more active
weather pattern. An approaching trough is currently off the California coast
near 135w…bringing up increased clouds and moisture some the south
into the western Great Basin for today.
As the trough moves closer to the coast on Wednesday…its expected
to pick up a slug of subtropical moisture. AMSU satellite precipitable water is
showing a deep moisture area off the coast of Baja California California at 25n
125w…with values of over 1.5 inches precipitable water. This will get pulled up
ahead of the approaching trough into California. It will be critical
to see how much moisture gets pulled north before the trough swings
through Wednesday night and Thursday morning.
This is not looking like a very significant precipitation event…although
certainly well needed. The main focus of precipitation will be in the High
Sierra…where quantitative precipitation forecast totals along the crest may reach up to around 0.5
inches Wed-Thu. Even though there is going to be a decent moisture
tap…this system moves through the region rather quickly…limiting
the precipitation amounts. The last few runs of GFS have been showing
greater precipitation down in Mono County…splitting the main chunk of
vorticity south of Tahoe. Comparing to the 00z GFS ens and ec…this
did not match up well…indicating that the 00z GFS was an outlier.
Trended the forecast toward Euro solution bringing a more consolidated
vorticity maximum into CA/NV. Increased probability of precipitation and quantitative precipitation forecast along the Sierra
crest…Cat for Mono County…likely pop up into the Lake Tahoe
basin for Wednesday night. Quick look at the 06z GFS…just coming
in…looks to be a good match to 00z Euro with low center tracking
over northern California instead of Southern California like previous runs.
Snow levels will be remain high…which is very common when we get
these subtropical moisture taps. 700mb temperatures will only get down to
around -2c in Tahoe and around freezing in Mono County…meaning snow
levels will start out near 8000 feet falling to 7000-7500 feet by
Thursday. This will keep snowfall to the higher elevations and
passes…with 3 to 6 inches expected above 8000 feet in Mono County
and south of Lake Tahoe. Not expecting any winter statements at this
time…due to the high snow levels and limited snow amounts.
Not much quantitative precipitation forecast expected for the leeside basin and valleys…including
Reno. May see a short period of spillover rain on Wednesday night…but
only a chance for now. A chance of convective showers expected for
Thursday as the trough moves directly overhead creating some instability
Long term…Friday through Monday…
models continue to have trouble with the overall pattern for this
upcoming weekend and beyond. A shortwave ridge is expected to build
into the Sierra Friday in the wake of the departing sheared out
trough. There may be some light showers still around but nothing
significant and kept low end chance/slight chance probability of precipitation.
Big spread in model solutions over the weekend and into early next
week provide little confidence in the pattern. There will likely be
a cut off low off the California coast with a secondary wave moving toward
northern California/Nevada out of northwest flow. The combination of these features should
produce some precipitation Saturday over the area…mainly over the mountains
but amounts do not look substantial at this time. By Sunday…the
low off the California coast looks to drop south and even slightly to the
west with a faster northwest/southeast flow into the Pacific northwest/northern California. There does
look to be a push of cold air out of the northern rockies and into the
Great Basin. How far west and south the cold air gets is uncertain
and will determine the amount of precipitation for the forecast area. The
most likely scenario…based on the greatest number of similar GFS
and Canadian ensemble members…would bring the heaviest precipitation over the
Pacific northwest with some showers over the forecast area as the colder air
drops south. Again how far west the cold air gets will determine
precipitation amounts. Will keep at least some mention of probability of precipitation all area
into Monday with this scenario.