Wednesday PM: 10-14-15

As we wait for the subtropical upper low to move on shore and spread precip north into the Sierra over the next few days….I have taken another look at the CFS vs 2. It looks pretty dry for the rest of the month of OCT. However, some of the long-range ensembles (Week 2) try to bring in a cool trof from the Eastern Pacific into CA.  The only comment I will make is that, this time of the year, (October) is the worst month for model accuracy. So they may be saying one thing and doing another.  Best to stick with the week at hand for best results. Climo wise, the weather does begin to change that last week of October so we’ll see.

ENSO:

Todays SOI shows tanking at -44!  So atmospheric coupling still well underway with EL Nino!

MJO: A strong signal is developing over the Indian Ocean the last week of October.  This might be why there is a weather system suggested by the GFS and EC.

However, the guys a CPC are not all that sure of the signal being a MJO.

 

Read from their latest discussion…

During Week-2, above-average rainfall is likely over the Central Pacific while below average rainfall is likely over Southeast Asia and the Maritime Continent. Both of those forecast regions are linked to the ongoing El Nino.

“Some models are indicating a strengthening MJO anywhere from Africa to the eastern Indian Ocean. Recent observation based analyses indicate a “Kelvin Wave” over the Central Pacific now, and typical propagation speeds would have the Kelvin wave located over the Indian Ocean, so at this time, uncertainty is too high to depict any large-scale, MJO-related impacts to that region”  

Note: I will update on the idea of either a MJO or KV Next Tuesday or Wednesday for that following week.

PS, if that emerging signal is a MJO, that would most likely bring a major pattern change to the eastern pacific that last week of October by flipping the PNA to Negative.  That would quite possibly mean “SNOW” for Mammoth

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Tuesday AM Update:

Today should be the last of record or near record highs as increasing cloud cover Wednesday will keep temps below any past records. From Southern CA inland, to the Central Sierra, Meteorologist’s are keeping an eye on the cut off low that’s been over the west,  for close to two weeks now. Latest IR Satellite loops are showing good upper divergence in NE quad. The upper low is expected to move into Southern CA Wednesday night with the location of the center of the low over the Channel Islands at 18Z Thursday morning.  It get the boot east into southern NV very late Saturday night….by an upstream Trof.   That next upstream trof is being handled differently by both the EC and the GFS with the GFS splitting it and the EC forming a coastal closed low. Thus the ECMWF is the wetter solution with the GFS about half as wet.  Will update again Wednesday to see how the models are syncing….

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Excitement in the weather about record heat followed by a Boomerang upper low later this week has folks scratching their heads wondering what is going on with the weather?  Yes there is an El Nino and the warmer than normal SSTs along the CA coast will supply additional moisture for another unusual weather event beginning Wednesday into the weekend. Snow levels will be very high until they come down enough to dust Mammoth Mt this weekend.  The Southern Sierra and even the mountains around the LA basin will get bulk of the precip with some areas like the past subtropical systems dropping over 2 inches of rain over favored terrain.  The waters are so warm off Baja and Southern CA that the models are going to underestimate the QPF.

 

So what is the history of this system: (At least from Memory); those that know more exact timing feel free to comment.

  1. It began as an upper trough that dropped south from the BC coast October 1st and 2nd as an inside slider inland over Washington and Oregon .  It dug back and closed off along the Northern CA coast early that weekend. The track took it all the way SSE to near Paso Robles/Santa Barbara, then ESE across Kern the Mojave desert.  Through the process, there were areas of heavy rain  and high elevation snow over the Southern Sierra, White Mts and mountains along the CA/NV boarder. The Southern Sierra east to Western NV got the bulk of the precip. However, there were reports of heavy rain showers in the LA area as well.
  2. The track of the upper center moved as far east as New Mexico before it dropped south over the Sonoran Desert of Mexico before last weekend.  As high pressure built into CA from the SW, the upper flow sent the upper low across the Sea of Cortez and off the coast of Baja early last weekend.
  3. Today the upper low is west of central Baja.  Although it may still be considered a cold core low. It has tapped into a lot of tropical moisture to its SW. As the upper high breaks down over the far west, the upper level system will lift into Southern CA Wednesday into Thursday.  Although the precipitation guidance shows moderate amounts of precip with this old low, looking at the latest satellite IR, you have to ask yourself if they are underplaying the QPF for later this week.  Nevertheless, it looks like primarily a Southern CA, Southern Sierra system east into South West Nevada storm. However, precip will spread well north into the Central Sierra. Amounts will be between .5 to 1.00 in favored mountain areas of Southern Mono County and the White Mts.

Just a quick update for the change in the weather for the end of the month. The CFS v2 still has cooler then normal temps with a long wave trof, south over the Great Basin, This is typically a dry pattern with light precip. The Dweebs will take another look at it next week….

 

Dr Howard and the Dweebs………………:-)