Archive for December, 2017

New Years day….12:15PM

Happy New Year everyone….   Hope its a good one….

The 12Z European Ensemble forecast model was still running with the Deterministic run still showing a pattern change in the offering. QPF continues to be scaled back and that means in general that these storms are weakening as they come in, due to the west coast ridge.  Light snowfall is still expected beginning Wednesday at elevations mainly above  8000 to 9000 feet. This does not appear to be a plowable storm for residential driveways for the vast majority of town.  As per this mornings CA Rivers Forecast Center, The Dweebs are not expecting much more than a few inches from this system, even over the higher elevations.  Looking at the 5 day means on the last ensemble run, the mean ridge position over the Central Pacific is between 150E and the dateline. This is not good….

500MB heights fall over time but remain higher than normal.  As mentioned earlier, the European model which is usually better at distance is showing a colder system for about the middle of next week with the chance of another following.  These storms will most likely weaken as they come in. However, they may provide some badly needed snowfall along with temporally colder temperatures.

Later in the week 2 period the new 12Z Jan 1, ECMWF Ensemble which has just finished running,  shows amplification of the Central Pacific ridge between 150E and the dateline. If this model ensembles verify’s, this in turn will ridge us back up again………

Dr Howard and the Dweebs………………….:-)

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I think that on an interseasonal scale of time, this is got to be one of the strongest and persistent Hemispheric Meridional Upper Flow patterns I can remember for a long time. The fact that the midwest and east is setting low temperature records are all part of this pattern, that is similar to the winter of 1917-18 I have read.  I am sure that the -QBO combined with La Nina has something to do with it. All models have done poorly with forecasts of both timing and details of guidance in their week two forecasts.  One only has to look at the non-details of the 5 day ensemble means of the ECMWF to see that a major wet pattern is not in the cards at this time. And…it is possible that we may be transiting to a pattern of one that is marginally wet before we go dry again.  We’ll see how the next 6 to 10 days develop in the week 2+ guidance.

On the bright side, it does look like that we may get one decent colder storm the following week, the week beginning the 8th. That may be enough to greatly improve our spirits!  The forecast for this upcoming week is one of unsettled weather with the chance of light precipitation beginning anytime mid-week (Wed) into the following week. The snow level along with the freezing level will remain fairly high, between (snow level) 8K and 9K. Based upon this mornings CRFC, the guidance suggests about 1/2 inch of water eq over Yosemite through Friday AM.  I will update later New Years Day Morning. However, that does not cover a more significant system later in the weekend or early the following week. Remember, the details are very poor because of both pattern transition and the mean ridge position over the far west. The upper flow mid-week is southerly, so orographics will not be a major player in the beginning of this pattern change.

PS I am still watching the MJO to see how strong it gets and how far east it gets…  That can make a big difference on how the pattern evolves…

More Later…………………….:-)

12-28-17 8:40AM

Quick update this morning shows upper west coast ridge holding strong through New Years Day. However confidence is high for the retrogression of the ridge during the 2nd week of January. A strong interseasonal signal points toward an increase in convection off the coast of Africa and east into the Indian Ocean as the MJO is currently redeveloping in that area as per IR Sat maps. SEE: http://tropic.ssec.wisc.edu/real-time/imagemain.php?&basin=indian&prod=irbbm&sat=m5

Here is another update on the MJO and its forecasted intensity:  This is the RIMM (Phase space) from the European 00z Thursday forecast run from last night. It clearly shows an intensification of the signal and a progression from where it is currently emerging, just over the western Indian Ocean.  http://www.cpc.noaa.gov/products/precip/CWlink/MJO/CLIVAR/ecmf.shtml

MJO’S convective envelope is just moving into the 40E area. Based upon the RIMM forecasts, intensification of tropical convection is expected in the coming days as the MJO either stalls out over the Indian Ocean or is progressive into the Maritime Continent.  This interseasonal signal often times affects the western Northern American PNA teleconnection which in its current phase is positive, to one that may become negative. -(PNA)  The hope is that the west coast ridge associated with the +(PNA) flips negative and a long wave trof sets up.

Note: There is usually a delay in the flip in the PNA signal until the MJO reaches the Maritime Continent or even the western pacific.

(Note the chart below)

The long-range guidance (Week 2) is responding, however, the timing and how the pattern change all unfolds is uncertain at this point. Timing is between the weekend of the 6th and Mid Month.  Although this mornings runs of the global models suggests that the pattern change will be slower, it could be quicker as well.  That is just an unknown.

Other climate signal’s and other thoughts:

For two weeks straight now the SOI has flipped on a daily basis to become negative, meaning that the trades have weakened significantly. This maybe due to an air-sea coupled Kelvin Wave or ??   Its affects are tearing the La Nina apart and will weaken it rapidly as we go into the spring. Once the ENSO signal crosses into LA Nada, if it happens early enough this Winter/Spring, we may begin to see “Atmospheric Rivers” return to the west coast again.

It is interesting or possibly coincidental that the MJO is moving through the Indian ocean and intensifying, while the SOI has become negative for an extended period of time……

Will this MJO or another following this Winter/Spring, be the catalyst for the Next El Nino?…..

The Dweeber………………….:-)

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10:45AM:

The new  12/27/17 12Z GFS is now singing the same tune of a pattern change the end of week 2.  (The Weekend of January 6th into Mid Month)

This is the best MJO signal I have seen this year.

Keep your fingers crossed….:-)

The Dweebs have been watchin and waiting for confirmation of a pattern change forecasted by the European Model for sometime in early to mid January…..The GFS American Models has not been in agreement. So the questions arises, which model is correct?  Although at this point there is no certainty, if the Dweebs use other climate forecasting tools such as the MJO in conjunction with the other global models, such as the Canadian and Japanese models, there appears to be more censuses that a strengthening signal will develop over the Indian Ocean over the RIMM phases 2 and 3:

SEE: * http://www.cpc.noaa.gov/products/precip/CWlink/MJO/CLIVAR/clivar_wh.shtml     One can derive a bit of bias because of global models such as the CMET, JMAN as well as the EMOM. All are pointing toward a strengthening signal over the Indian Ocean.   A strengthening signal in that area foretells a flip in the PNA teleconnection from the current positive mode to negative. A negatives sign PNA is associated with troughing instead of the current ridging we currently have over the far west.

*Dynamical model MJO index forecasts quite consistently show a re-amplification of the MJO signal as it enters the Indian Ocean, moving away from peak destructive interference with the La Nina signal. Should this occur, Indian Ocean MJO events teleconnect well with the North American mid-latitude circulation, and the MJO may therefore help effect a pattern change in the late Week-2 or Week-3/4 period.