Archive for February, 2016

Winter Storm Warning Now Hoisted by the NWS beginning 7:00PM Wednesday through 12:00PM Friday….Expect a dry…..Partly cloudy and breezy weekend

A WINTER STORM WARNING NOW HOISTED FROM THE NWS Wednesday from 7:00PM to 12:00PM Thursday….

 

SEE:   http://forecast.weather.gov/showsigwx.php?warnzone=CAZ073&warncounty=CAC051&firewxzone=CAZ273&local_place1=13%20Miles%20E%20Lee%20Vining%20CA&product1=Winter+Storm+Warning&lat=37.939&lon=-118.887#.VsNppbQrKig

 

9:00AM Tuesday:

Although the Wed/Thur storm system is on track to bring a good foot to the town at 8000 feet and between 18 and 24 inches over the higher elevations; there is a substantial warm sector that will have plenty of QPF that will fall as rain over the lower elevations. Snowfall Accumulations will be tricky in town as amounts will depend upon how quickly the freezing level comes down. CRFC has the freezing level at Yosemite at 9800. at 10:00am Wed,  and 8300 at 4:00PM Wed.  The snow level is often times as much as 1500 feet below the freezing level; So it may be sticking snow over the upper elevations of town by Sunset.  The *IOP is between 10:00PM Wednesday and 4:00AM Thursday with an inch of QPF predicted for Yosemite.   Additionally, it will be very windy Wednesday ahead of the storm.   Wind advisories or even High Wind Criteria will likely be met by Wednesday afternoon. Because of the nature of the storm, and in that it is progressive through the sierra, there will be much less than the normal shadowing….eastward..

Thursday will be 20 degrees cooler than today with snow or snow showers depending on how fast the system exists.  It looks quite breezy Friday and Saturday then another ridge builds in Sunday into Monday next week.

There looks to be some rather windy systems coming in, prior to the end of the month with amounts in the light to moderate range.

 

Weekend Outlook:

Without any strong ridging and a SW flow aloft, it will be quite breezy early in the weekend with lower wind speeds Sunday into Monday…..

High in the 40s Saturday then low 50s Sunday….Lows in the teens and 20s….

Longer Range:

The El Nino/MJO forced pattern change has been pushed back to the first week of March….

*Intensive Operational Period

Upper ridge to build and progress over California Today and Tuesday…..Warmer days expected…..Midweek Storm a Fickle One…..Now includes a Subtropical Tap…..Snowfall amounts increased for Wednesday Night and Thursday AM……It looks to be a windy one as well…..

 

After a couple of mild days early this week…..The Dweebs have seen more model consensus indicating a substantial subtropical moisture tap, that increases the QPF from moderate to now possibly heavy on Mammoth Mountain Wednesday night and Thursday.  Overall, snowfall amounts will be determined by how quickly the short wave moves through.

Both EC and GFS are showing a nice but brief subtropical tap of about 6 to 12 hours, that will act to prime the pump in advance of strong dynamics that will move through the Sierra Later Wednesday Night and Early Thursday AM.  Additionally, this system is not likely to split. It will move right on through the Sierra with good orographic’s.  

 

The storm will benefit the Central Sierra and Southern Sierra…Southern CA will see little if any precip.  The WPC QPF is between 1.75 and 2.00 of water EQ, enough for a 8  to 15 inches of snow in town and 18 to 24 inches over the higher elevations by Friday AM.  The snow level Wednesday afternoon is above 8,000 feet but will fall to 7000 by 4:00PM Wednesday and down to 5000′ by Thursday mid-morning.    

 

For the folks that are planning on coming up to the Sierra the following weekend, it looks very breezy over the top with temperatures at 10,000 feet in the 30s. Highs over the lower slopes and in town in the 40s. Expect lots of clouds, but  dry.  Expect packed powder conditions as well, So if you liked the snow this past weekend, the snow conditions will be twice as good next weekend.

PS there is a smaller feature showing up Friday night into early Saturday AM that may bring a few more inches of snow to the high country toward the end of this week.

FROM WPC:

THE ENSEMBLE SHOW A FAIRLY STRONG AGREEMENT IN THE EVOLUTION OF THE DEEPENING DEEP LAYERED TROF…THAT IS SEEN WELL BY THE WARMING WITHIN THE WAVE WEST OF THE ATMOSPHERIC RIVER WEDGE BOTH WITHIN THE LARGE SCALE AS WELL AS WITH SOME OF THE SIGNIFICANT INTERNAL FEATURES. THE SHIFT NORTHWARD OF BOTH THE 12Z NAM/GFS FURTHER TIGHTENED THE AGREEMENT IN TIMING/ORIENTATION OF THE TROF AND WITH STRONG AGREEMENT WITH THE 00Z ECENS MEAN AND 06Z GEFS…CONFIDENCE IS SLIGHTLY ABOVE AVERAGE IN THIS SCENARIO GIVEN THERE IS STILL TIME FOR ADJUSTMENT OF SOME OF THE SMALL INTERNAL DIFFERENCES. THE 00Z UKMET/CMC ARE BOTH OUT OF PHASE TO NOT PREFER THEM IN THE BLEND AT THIS TIME.

 

Dr Howard and the Dweebs……………………:-)

 

Upper West Coast Ridge will weaken this weekend then redevelop off shore and build over CA early next week…..Mid Week storm looks to be a moderate one with no Subtropical Tap….

Saturday AM:

Clearing skies were in process this morning and temperatures were running a few degrees cooler. North winds will be on the increase later in the weekend and into early next week as the west coast upper ridge redevelops over the far eastern pacific and builds over California Monday into Tuesday.  As the Dweebs have said many times before, the Town of Mammoth is protected from moderate to strong North Winds because of the Topography. The Sierra Crest and north-south valleys are the exception where north winds can rip through Mono County south thru the Owens Valley.  This looks to be a light to moderate north wind event for later Sunday and Monday.  Holiday Travelers’ heading south down the Owens Valley Monday should get excellent gas mileage with tail wind gusts to 40 mph.

MJO:  Although we have a moderate storm for Wednesday and Thursday, the Dweebs main attention is on the inter-seasonal outlook for the end of the month and 1st week or two of March.  Some things are beginning to happen that are showing support to the MJO on the move.  This morning, the Southern Oscillation Index (SOI) went negative at -14.17.

 

SEE:  https://www.longpaddock.qld.gov.au/seasonalclimateoutlook/southernoscillationindex/index.php

 

This index represents the gradient between Darwin over North Australia and Tahiti. When it is negative the winds are moving from west to east near the Equator in the southern Hemisphere.

In order for that to happen during an EL Nino you need to have convergence aloft or a general sinking motion in the Troposphere. It just so happens that the MJO as it leaves the Maritime continent north of AU, has sinking motion (Upper Convergence) in it rear.  This gives notion that the MJO is progressive and now moving into phase space 6.

SEE: http://www.cpc.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ECMF_phase_MANOM_51m_full.gif

I expect the SOI to continue crashing over several days to come.

The border of Phase Space 7 and 8 is near the dateline and where the MJO, should it remain strong, will constructively interfere with El Nino. It will weaken as it moves towards an area south of the Hawaiian Islands in Phase 8.  By the end of February, the MJO should be very near phase 7/8. This location often times forces the extension of the East Asian Upper Jet to the west coast.

Stay Tuned

Dr Howard and the Dweebs………………………….:-)