Thunderstorms to Redevelop Again today and Wednesday as Upper Cut Off Low Remain West of Santa Barbara Today….Upper Center to begin lifting toward the Bay Area Wednesday…..Drier Air to begin mixing in Wednesday Night…..Fair…Dry Warm Weather expected Thursday Through the Weekend……
Tuesday August 20, 2013
Posted at 10:07 am by Howard
Wednesday AM Update:
Few showers dampened the ground at Snowcreek this AM. More on the way.
Wave loop showed Upper cut off just a tad south of Monterrey Bay. I love the way cut offs wobble! Amazing! It was evident that the upper flow has become more south/North orientated as compared to SE/NW which is more of a divergent pattern more conducive to synoptic as compared to meso scale lift. The showers for this AM have already moved north to about Hawthorn, NV.
At 9:00am….Mesoscale Analysis this morning showed a weak area of convergence over the crest and a sharper Surface thermal trof west of the Crest then yesterday AM. A strong area of Divergence aloft at 300mb was located along the boarder of Mono county and NV. Lifteds are about -1 to -2. PWAT is higher today over KMMH at .85 and a large pool of PWAT of 1.1 along the Inyo County boarder and NV inc DV. Looks like another day of tsrws with terrain driven Convergence from TSRW outflow aiding further development as well.
In that the Upper Cut off is now on the move…today and this evening will likely be the last of the rainfall for Mammoth for a while. Thursday through Tuesday looks Dry and warm with dry and cooler nights due primarily due to lower dew points rather then any synoptic cooling. However, any existing fires will likely become more active due to the dryer air and gusty winds over the coming days…
The only fly in the picture for Sunday will be the northern extent of a Gulf Surge that is expected to be initiated by TS IVO This weekend. Southerly flow looks strong enough to blow up the Gulf of CA where SST are running as warm as 91F and Dewpoints in the high 80s, north into the Southern Deserts of Ca and southern NV east to Western AZ…..Sunday and Monday. This maybe classic Gulf Surge, Flash Flood Pattern for Coachella Valley, Southern NV/Colorado River area. For those in the area, keep weather radios handy and follow NWS advise.
Looking at the SPC Mesoscale Analysis page for the NWS, its apparent that the forcing we had yesterday and the day before is not nearly as strong this morning. Nevertheless, the upper cut off is still churning off the coast of Santa Barbara and the upper flow is still SE. PWAT is a bit lower this morning over Mammoth. But skies are clear and the Sun will heat things up pretty quickly with highs well into the 70s. So the Cu will pop and thunder will occur this afternoon but rains may not be as wetting as yesterday because of the lack of an, 850mb-250mb couplet. Yesterdays storms brought .33 of an inch of rain to MammothWeather.com near the Village.
In that the upper cut off will begin to make its move late tonight or Wednesday, there will be another chance of thunderstorms again tonight and Wednesday. By Thursday into Friday the system heads to its grave yard over the pacific Northwest. Thursdays storms will be mainly north of highway 80 and the Northwest.
Dry southwest flow returns this Thursday through next Wednesday. (Warm and Dry) Thereafter, the upper flow backs to the south again for some moisture, extra warmth and possibly some showers or thunderstorm’s later next week. Worth mentioning….Additionally, with the MJO protruding into Phase 8 tropical storm development will increase in the Eastern Pacific with greater chances for warm or hot humid weather and some rainfall for Southern Ca next week.
Although the longest range guidance is suggesting possibly another cut off 2nd half of next week with moisture advection and air mass modification….another maverick worth keeping an eye on is that the CFS model interseasonally is suggesting another heat spell, late during the first week of September. There are some ensemble members of the GFX that bring in a 594+ DM upper high from the eastern pacific and progress it into CA. Both 06z and 18z runs as of late included. Other runs develop it more as more of a retrograding upper high, with more hot continental air setting up of over the Inter mountain west. I think that with tropical storm development in the western pacific increasing because of the MJO then recurring to the NNE, there will be lots of possibilities…..Stay Tuned…September may be wild!!
The following statements/conclusions are my opinion as a hobbyist only……
1. The interseasonal (week 3) shows quite the heat spell for Ca with the long wave upper ridge set up at about 125W and the upstream Trof at 155W. Several Runs of the GFS has a deep trof between 160W and 155W. Additionally, a Tropical storm recurving up toward Japan amping the pattern from upstream……
2. There is a very large warm body of SSTA between Hawaii and 130West. The only really cold water at the surface is from about just north of the Bay Area south along the coast to most of Baja Ca.
“I think” that this could be a prime set up for significant Hot Dry Santana wind system that may develop several times in September into October. The first may be toward the end of the 1st week of September.
If you live in the foothills of SC, like always, take all precautions! IE Clear brush etc….This looks to me like a rough late Summer and Fall.
At this time there looks to be a lot of amplification over the central pacific early next month, but the models will not have a complete handle on it for quite sometime.
Will update later on the possibility of an offshore wind related heat wave for Southern Ca next week….