Archive for November, 2012

Warming Trend in Progress as a Strong Progressive Anti Cyclone Dominates California WX Through Tuesday…..Big changes on the Horizon During the 2nd Half of Next Week….

Models continue trend of yesterday with upper trof deepening more over Ca and not off shore.

Quick look at the last nights EC QPF percip forecast shows about .5 to .6 over the crest between Thursday and Saturday. This is the upper limits for Dweebs criteria for Light amounts. Snow to Water ratios will be high with 500mb temps below -30 and thickness dropping into the low 530s so 13: to 1 best Est for 6 to 8 inches at 9000.  Will look more closely at any possible orographical effects that may sku precip….

 

The Dweeber…………….:-)

 

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The Dweebs are glad to see November shaping up with some cold weather ahead. Good for the ski area and good for the economy. We still have one more warm up to get through. It will be warm enough for highs to reach the low to mid sixties in Mammoth Tuesday. That is a pretty good feat this time of the year!

Looking at the guidance now, models are coming more into sync showing a very cold trof that makes its way into the area, during the day on Thursday. Along with the Trof will be a fast moving cold front that will most likely give some pretty strong winds to our region as antecedent conditions will be quite warm for this time of the year and thus the surface gradient pretty intense.

Now for the latest on the precip. Although there is still time for an adjustment otherwise, both EC and GFS have come into sink as far as their trajectory over water. It is more to the east now than the past few days. So there will be less over water trajectory for the strong upper jet to work with. The EC has backed off on amounts for the crest to about 7 tenths of an inch. That is a lot less then it was a few days ago when it touted as much as 2 inches. So best guess at this time is that mother nature stands to lay down between 8 inches and a foot. Lets hope the trof digs back a bit west over the next few days, so that amounts swings back wetter again.

Mammoth usually gets about 10:1 for snowfall ratios. However, in a particularly cold storm, the ratios can increase dramatically. This storm will more likely squeeze out a higher ratio then average, as 500mb temps are less then -30 in this trof and a cold 1000-500mb thickness pool of 528dm is associated with it. .  Additionally….Mammoth Mt will be able to really lay it down beginning Friday then through the weekend as snow making will be round the clock!! “Best confidence in “snowfall amounts” will be by mid week”  However, the Dweebs will update daily……

 

Dr Howard and the Dweebs………………………:-)

 

 

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Reference Glossary of Weather Terms
Disclaimer: I have been a hobbyist meteorologist for over 30 years here in the Mammoth area and I do this for my personal enjoyment. The National Weather Service saves lives every day . . . I do not. When making important planning decisions please use information provided by the National Weather Service as they are the most knowledgeable and accurate information source available today.

Warming trend is now expected through early next week as an Anti-Cyclone rolls in from the West…..The Dweebs are still watching a Storm System that may bring decent snowfall beginning next Friday….

Saturday 5:00pm

Just had a look at the latest 12z EC and the 18zGFS.  Both are singing a similar tune. The 12z EC came in drier than lasts nights 00Z run. It showed about an inch over the crest. It seems like each run adjusts a bit more east,a bit more west.  When it adjusts west, the upper jet can develop more QPF,  then when its time over water is more limited during an eastward shift.

The Dweebs feel that no matter how moderate or heavy next weekend’s precip is…there is beginning to be a trend that shows a pattern that is originally split with two storm tracks that finally consolidates beyond 240 hours.

The western pacific portion of the GFS guidance shows both a progressive pattern…..and a series of either cold migratory trofs or cold closed lows moving off the Asian coast. Then beyond 300 hours……in fantasy land, some serious wave crashing west of the dateline that attempts to build a full latt ridge well east of the dateline at about 160W.

 

The Dweeber……………………….:-)

 

Friday Afternoon 4:00pm

Just a quick note to let folks know that the Nov 11th 12Z ECMWF has come in further west, Stronger, and much wetter then earlier runs. Even though the GFS has the same trof that the EC has, it is not nearly as wet/strong.

The EC paints about 2.5 inches of liquid EQ over the crest beginning Wednesday Night through Sunday morning. Although there is plenty of time for things to change, this is beginning to look like Mammoth’s first major storm for the 2nd half of next week.

Being that we are now back to the 7th/8th for the onset, Confidence will rapidly increase by Monday either way.

Stay Tuned>>>>>>>>>>>>>>>>

 

It was a chilly morning this morning here in Mammoth. Temps bottomed out in the upper 20s. A thick frost developed on the roofs of town as moisture left from yesterdays showers….along with strong radiational cooling last night provided for some glistening…..

The next weather feature headed our way is an strong progressive anti-cyclone aloft.  This will have the effect to generate some east wind and general off shore flow for the southern 2/3rds of the state. At 500mb, Sunday nights heights rise up to 588DM with the upper flow N/S over Mammoth. The core of the Anti Cyclone at 125W and 36N is forecasted to be 593DM at the same time. Off shore flow will be well established over most of California, then becoming more easterly with time into Monday/Ngt. The core of the upper cyclone then weakens as it moves onshore with 500mb heights centered over Fresno of 586dm at 10:00am Tuesday. Temperatures will change little between Monday and Tuesday. Expect temps between 10 to 15 degrees above normal for this time of the year.  Expect high temps in the low 60s in Mammoth…..and upper 70s for Bishop)

The ridge weakens rapidly the following Wednesday giving way to a significant Trof Friday/Saturday.  Last night’s 00z GFS and EC both showed a trof that was much more amplified then earlier runs along with an accompanied 140knot upper jet at 300mb. The nose of this upper jet makes its way into the Bay area by Friday.  The EC “was” more amped then the GFS. Then the…..the 06Z run of the GFS came in about with the same amplification as the EC.

Last night’s EC showed between .75 and 1.00 inches over the Central Sierra for the following weekend. Again the 00z run of the EC was much more amplified (deeper) than the 00z GFS. I will say that the ECMWF has been much more consistent. So….even though there were some runs earlier in the week that did some back peddling, it appeared that the EC is doing a better job.

Best confidence usually develops within the 3 to 5 day period before the event, especially if both models come into phase with their operational runs and short term Ensembles.

 

Have a nice weekend!  Looks like we get another warm 3 day period to do some winterizing work outside…..

 

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

 

————————————————-
Reference Glossary of Weather Terms
Disclaimer: I have been a hobbyist meteorologist for over 30 years here in the Mammoth area and I do this for my personal enjoyment. The National Weather Service saves lives every day . . . I do not. When making important planning decisions please use information provided by the National Weather Service as they are the most knowledgeable and accurate information source available today.