Big Wet Storm in process with lots of rain Tonight and Friday…..Big PWAT Plume pointed at Mammoth…Snow in the Town of Mammoth Sunday/Night…
Thursday October 27, 2016
Posted at 5:56 pm by Howard
Storm 1. Just like I said….Models do not handle Subtropical moisture very well. Most of the models had the bulk of the precipitation further north of Mammoth but they have been back peddling south the past two days. 500MB 567DM upper low is west of Pt Conception with both subtropical and weak southern branch of the polar coupled well west of the coast. Seymour has been down graded to TS and is still pumping a lot of heat into the system thus doing the job of Jet stream enhancement. PWAT plume of 1.7 to nearly 2.00 off the South Central CA coast with the trajectory into the Central Sierra. This is +5 to +6 Sigma as far as the anomaly.Thunderstorms a good possibility over the southern and central San Joaquin Valley and into the sierra tonight.
No doubt the QPF Bull’s-eye is over the central sierra on this 1st storm. Get ready for some heavy rain later tonight and possible thunder. Heavy rain will occur after midnight tonight as well into Friday morning. Again this is not and I repeat not an AR event, no matter what the Colloquia’s want to say. This PW plume is wider than long. AR events are fairly narrow rivers of high PWAT that stretch thousands of miles usually West to East or SW to NE. This one is an inverted V. PWAT is not the only definition for an AR.
Storm 2. Sundays storm will drop 12 to 18 inches over the crest and possibly 4 to 7 in the Towns of Mammoth and June.
Storm #3 is minor with lights amounts. “Monday Night” (A trace to an inch)
October 2016 is on the threshold of record rainfall here in the Central Sierra.
Dr Howard and the Dweebs…………………………:-)
Height Rises to provide warmer days and a bit of a break in the wind later today and into Wednesday….Next short wave to tap Bonanza of subtropical moisture from north of ITZ and remains of Hurricane Seymour with potential for another rain event for the high country Thursday into Friday…….Cooler system to move in Late Saturday night with the chance of some snowfall to the Towns of Mammoth and June Sunday AM….
Tuesday October 25, 2016
Posted at 9:31 am by Howard
As the pattern evolves this week, the picture is becoming increasingly clear that another wet storm is in store for the Central and Northern Sierra for Thursday into Friday and a colder system late Saturday night into Sunday with Showers possible Monday. The first system has a big tropical/subtropical tap all the way down to north of the ITZ and no doubt has moisture from Hurricane Seymour. PWAT is forecasted at high as 1.50 to 2.00 inches along the coast of Central CA Thursday AM. A healthy subtropical jet of over 100 knots is associated with it. The freezing level is expected above 11,000 feet and so for the most part, this is going to be another rain event for Mammoth and the Eastern Sierra Thursday and Friday. The forecast models are now showing a colder system for Sunday morning that may bring snowfall into the Towns of Mammoth and June Sunday morning and into the afternoon. Amounts are uncertain depending upon how much moisture remains when the cold air arrives Sunday AM.
Back to the details of Thursdays/Friday’s Storm….
A large deep upper low near 50N/132W will initially steer a very dynamic impulse through a deep area of low pressure into the pacific northwest tonight. Thereafter, strong southern stream energy approaches Southern and Central CA later Wednesday. This will provide an extensive surge of pacific moisture directed at much of California. The fetch appears to have both Subtropical moisture from north of the ITZ, combined with eastern pacific tropical storm Seymour inflow. This is not actually an “AR” but the effects would be similar because of the strong moisture transport ahead of the short wave and the subtropical upper jet reaching deep into the subtropics. The big question this morning is….how quickly will the moisture move out or get cut off? This is because, as the long the fetch remains intact, the faster the rainfall totals will accumulate. Forecast models are not all that good in handling tropical moisture influx in this part of the world. So no doubt they will be playing catch up as time gets closer and the timing becomes more clear.
As a comment……..Burn scar areas along highways 395 dodged a bullet last storm that brought about 4.00 inches of rain to Mammoth Lakes two weekends ago. This coming Thursday into Friday afternoon storm has the potential to bring another 2 to 3 inches of rain at this time. 7 day forecasts of QPF are again in the 4 to 5 inches range again according to WPC’s QPF center.
Another Active 2nd half of the week is expected with the potential of more heavy rain Thursday Night into Friday….October rainfall records look to be in jeopardy….
Monday October 24, 2016
Posted at 10:00 am by Howard
The front left exit region of the subtropical jet is creating the lift this morning to produce some light rainfall in the Town of Mammoth. Once this wave passes we will have lots of clouds the next couple of days but dry weather. A long wave trof has taken up residence over the Eastern Pacific. However, too far west for cold enough air to bring snowfall to the Town of Mammoth. Heights remain in the low 570s DM at 500MB, so we are in the sweet spot for rain and tropical moisture but little in the way of snowfall at the 7000 to 8000 foot level. This large-scale adjustment wave will continue to send several shot of energy into the west coast over the next 6 to 10 days affecting the central sierra periodically. The most significant development is hurricane Seymour off the coast of Central Mexico. This moist system will be moving over colder waters soon…thereby dissipating and releasing its moisture into the surrounding area. With the long wave located at 135 west and a rather sharp short wave progged Thursday AM, no doubt that there will be some heavy rainfall headed for the Sierra Thursday afternoon into Friday AM. The PWAT from that fetch is forecasted to be as high as 2.00 inches Thursday AM just off the central coast. Rainfall amounts may tally similar amounts that occurred weekend before last, tying all time October rainfall records for the Central and Northern Sierra.
As far as snowfall, most of it will be above 9500 to 10,000 feet again. At the moment, the OIP looks to be Thursday night into Friday AM.
+SSTA’s are still warmest in the North Pacific. If they remain their, that would lend bias to some mighty cold weather later in December and January. As mentioned in a past discussion, this is a winter that will be difficult to forecast as the climate models have not done a good job so far. I would not put .02 cents on any long-range forecast at this time. As an example Scripps forecasted a “strong La Nina” last Summer and that goes against most climate models now. The PDO as become neutral the past 2 months and there is only speculation on what it will do this winter. If the Warm Blob backs into the NE Gulf of AK again, there goes our winter. If it remains weak, with anomalous SSTA warmth continuing over the north pacific, that would be more interesting for a normal to wetter than normal winter. The Climate models can forecast all they want but if they do not pan out, they are worthless. Best to stick to the week one and week 2 forecasts and track the MJO for highlighted weather events this winter….
Note; the Dweebs will take a hard look at things later in November to see if there is more consistency in the climate models and at the least, the forecast of the PDO and ENSO.