San Juan Mountains Weather Report ~ 2/29/16 .. Pattern change in the future..

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In our last forecast two days ago, 2/27/16 the absence or late return of el Niño was discussed and I mentioned the second week of March as a possible resumption of moisture flow to the San Juans.  I corresponded with Joe Ramey, NWS forecaster in Grand Junction …  here’s our email exchange.

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On Monday, February 29, 2016 9:37 AM, Jerry Roberts <jerry@mountainweathermasters.com> wrote:

Hey Joe..
Read this morning’s NWS forecast discussion and looked closely at the final line. What indicators are you guys looking at for the 4-corners lows to begin again?
salud
Jerry

“THE CPC FORECASTS WELL AND LOOKS REASONABLE AS WE EXPECT
THE `EL NINO` FOUR CORNERS LOWS TO START UP AGAIN SOON.” NWS

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Hi Jerry,

So since about February 7th, we have had a maleable ridge over the West Coast to Great Basin. Actually the larger pattern is a persistent trough in the Aleutians, ridge western U.S., trough over Hudson Bay-Midwest. Anyway, Pacific storms have been able to move the western ridge but they lose nearly all their energy as they pass here. Thus we are staying nearly fresh-snow free. This is the dry period I promised for January. What’s one month amongst friends? 🙂

What seems to happen on about 7 March, is a shift of the whole big trough-ridge-trough pattern eastward so that the ridge is pushed onto the Plains. This would open the door to more active weather here with the GFS producing a El-Nino-like closed low over New Mexico, Tuesday 8 March. The European model disagrees with that detail but also has us in an active trough. This type of pattern change is also expected during El Nino years, a snowy March-April.

What worries me is both models show a ridge rebuilding along the West Coast on 9-10 March. So I won’t be betting my 401k on the details at this point.

Other climate news, the weekly Nino 3.4 temperature anomaly is down to 2.1 which is the lowest value since October-ish? Strong El Nino is defined as >= 1.5, so we are still plenty strong. The latest outlook is still heading towards Neutral ENSO by early summer and La Nina by next fall.

Best,
Joe

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61976548-3937-4f2d-8eeb-5ef64dd0012d

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Below, 500mb geopotential height analysis, taking us through Tuesday, March 9th.

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500mb Geopotential Height – 12z GFS

A potential pattern shift sometime after the 1st week of March
The obvious feature appears in the March 7/8 time frame, in the form of a longwave trough across the west & closed UL low pressure south of Colorado.     Barlometer

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