Update on July 29, 7:45 am - cg
Notes from the morning discussion:
the elongated east-west upper ridge extending
across the Gulf Coast states through the desert SW has effectively
cut-off the deep layer to the south of Utah. The moisture that is
available across southern/cntrl/ern Utah will struggle to generate deep
convection again today. Subsidence associated with the near 700mb
high pressure across central Utah will inhibit convection outside of
the higher terrain where differential heating will come into play.
cg - The above says it all. The axis of the ridge that blocked moisture from yesterday is oriented in a way that will likely block the surge of moisture again today. This with a little high cirrus over the afternoon will likely suppress the triggering of deep convection, so TS will be more isolated and not scattered. Chance of TS is likely on the order of 10% for our region.
Friday Overview: The GFS model is showing considerably more moisture in the valleys surrounding Richfield tomorrow than the NAM does. The same was for Thursday, where conditions were by all means stellar for a task to the north with no overdevelopment within the area. This leads me to wonder about the validity of the moisture within the BL and aloft for Friday afternoon. To error on the conservative side, Friday will likely overdevelop by late afternoon within the region.
Saturday overview: Saturday is proving to be a difficult day to forecast. While NWS forecast discussions are stating that starting this weekend a surge of moisture will flow through southern and central Utah. However, there is indication that this may in fact be timed Sat night. Which leaves the early afternoon as a wild card. When these "pre monsoonal" conditions exist (if that's actually a real term) the spread of moisture aloft in stronger southerly flows, along with the destabilization within that flow, will allow for localized lines of overdevelopment as we have seen over this week, and then very widespread thunderstorms shortly beind. GFS shows strong southerly winds starting at 8am as low as 18k ft over 20 mph. This alone is perhaps enough reason to wright off Saturday as potentially taskable. This is also in line with the NWS discussion for the central Utah region.
** Saturday needs more consideration and review at this moment. **
The NWS synopsis:
Area forecast discussion
National Weather Service Salt Lake City Utah
341 PM MDT Thursday Jul 28 2011
Synopsis...a drier westerly flow will persist through tonight. The
very moist airmass to the south of Utah will begin to move north
through the state tomorrow before becoming well established
statewide this weekend. Deep moisture will remain in place into
middle week of next week.
Over Development & Precip
Friday will bring more moisture into the area as a south westerly flow aloft starts to set in above 500mb. This is not good news for our area in general, but as stated above, we may actually see usable conditions early afternoon before overdevelopment begins. Precipitable water will increase as wel (something on the order of .75 to 1.0) for this area. In a nut shell, this means that heavier rains will accompany and convective cells that drop out.
Winds 11 AM
| Height | Direction | Speed | Notes as the day evolves |
| Surface | S | 0-5 mph | SW throughout the San Pete valley |
| 9000 ft | ESE | 0-5 mph | Changing to light and variable for the afternoon |
| 12000 ft | ESE | 0-5 mph | Changing to light and variable for the afternoon |
| 15000 ft | ESE | 0-5 mph | Changing to light and variable for the afternoon |
| 18000 ft | W | 0-5 mph |
East winds on launch in the morning may delay the start window or provide difficult launches until the west slopes can heat enough to block the morning flow.
Lift Potential & Clouds
- Cumulus clouds: widespread, bases from 15k up to 16k as the day evolves and deep cumulus develop.
- Top of lift: estimated at around 15,000 ft over the higher terrain, with valley climbs up to 12-13k.
- Cloud cover: cumulus with widespread mid stratus are likely for the afternoon. High clouds will increase throughout the day.
XC Skies 3 day Trends
Legend: |  | Red - Top of usable lift (1.2 m/s) Black - Thermal tops (TI~0) | White - Thermal top sensitivity(+2°C) Pink - Cu CCL (dew pt.) |
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