Friday, July 06, 2018

Strange Brew Of Weather - But Rain In Gauge

There has been a bit of many weather things here at house since early afternoon yesterday (see previous post). When I left to walk this morning at 5:30 am MST temperature was still at 88 F, with strong east winds of 30 to 40 mph. The time-series below is of T and Td at the Atmo weather station - note the little blip of rain-cooling around 4:00 pm when there was 0.01" at that site. The storms did not do not much to cool things down - high at airport was 110 F before the convection boiled up. With the east winds continuing through the night the temperature has held constant around 90 F through the night and early morning hours.

The WRF-GFS forecasts for the wind profiles upstream from the Santa Ritas have apparently verified well. The RAWS site at Mt. Hopkins has been measuring gusts of 50 mph or higher since 7:00 pm last evening - latest observation indicated a gust to 80 mph.

The ALERT rainfall (above from Pima County) and the CG flash density (below from and Vaisala) show the north-south band of rain and thunderstorms across the metro area, where there was apparently a nice zone of moisture convergence. Total here remained at 0.13" since yesterday's post. Most reports around 1 to 2 tenths, but two sites north and west of Catalinas reported over half an inch.

The TWC 12 UTC sounding above (from SPC) indicates a bit of mid-level CAPE today, with PW up to 1.25 inches. Note that there are two residual boundary layers this morning - one from surface to 800 mb and the second from 700 to 550 mb - there seems to be a mixing and capping layer between the two.

The 12 UTC 250 mb chart below (from SPC with streamlines) shows the huge extent of the CONUS anticyclone - centered over western Arizona, but extending eastward to Kentucky. The heights at 500 mb over the Southwest this morning are right at 6,000 m!

We are now in a regime where the small day-to-day variations within the anticyclone, as well as moisture intrusions and moisture recycling, will determine the short-term weather, resulting in little predictability beyond days one and two. With that in mind, the only forecast I'm showing this morning (below) is from the 06 UTC WRF-GFS run at Atmo. Forecast is for total rainfall through midnight tomorrow night. Thus, mostly wind and heat in the short term - but yesterday was a nice surprise, at least for parts of the metro area.

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