It's Third Week In May, But ........

Photo son Jason took while was playing in a golf tournament near Denver yesterday. He was on back nine but tournament called and cancelled right after his photo.

Yesterday's severe thunderstorm reports (above), indicating nasty storms and some tornadoes from west Texas into Missouri. Very unusual Arizona tornado reported northeast of Flagstaff - during thunder-snow storm?

Across metro area there were some reports of 0.04" or bit more in the north part of ALERT network - reports below were for 24-hours ending at 5:00 am MST this morning.

Here at house we had 0.05" from a morning shower. Low here this morning dropped to 44 F!

Windy afternoons continue today and tomorrow. Down at bottom is 06 UTC WRF-GFS forecast of 10 m winds valid at 2:00 pm tomorrow on the 22nd. Note the very pronounced mountain wave pattern from southeastern Arizona and northern Mexico northeastward across much of New Mexico.

Unsettled Week Ahead

Cool and unsettled week ahead as 500 mb trough persists over the West. Some light showers and sprinkles around metro area this morning.

This morning's 500 mb analysis (above from NAM) indicates short-wave trough over southern California. The 12 hour forecast, valid at 00 UTC this evening (below), has the short wave over eastern Arizona and New Mexico, as a trailing short wave digs southeastward.

Plot of CG flash density (above - 12 hours ending at 7:00 am MST this morning - from weather.graphics and Vaisala) indicates some thunderstorm activity occurred north of Catalinas. WRF-GFS forecast from Atmo run at 06 UTC forecasts light showers for our area (forecast below ends at midnight tonight).

The Storm Prediction Center forecasts a major outbreak of severe thunderstorms over the southern Plains today, as the strong short-wave approaches.

Some snow yesterday and last night in northern Arizona - view below from a bit after 7:00 am is at the south entrance to the Grand Canyon.

Windy As Week Ends

Gusty winds in model forecasts for tomorrow afternoon and also Friday afternoon. Winds result from strong system off west coast moving east-southeastward into the Great Basin. Above is 06 UTC WRF-GFS forecast from last night of 10-m winds valid at 1:00 pm MST tomorrow

Took a look at CG flashes from Mexico southward into Central America this morning. Plot of detected CG flashes (below, for 12-hours ending at 06 UTC last night - from Atmo and Vaisala) indicates Mexico quiet west of Continental Divide with most activity far to south over Central America - seems a bit far south, reflecting the persistent western U.S. trough. Will start keeping close tabs on the activity.

Also of interest, the eastern, north Pacific hurricane season begins today.

Quick Weekend Summary

There was a heavy thunderstorm just to east aorund 3:00 pm MST yesterday afternoon - view above and composite radar below. But, as is often the case, it fizzled and weakened. So much thunder here but only 0.13" - making weekend event here only 0.23".

ALERT plot of rainfall for 24-hours ending at 7:00 am this morning is below - fairly moisture-starved event with amounts mainly less than 0.20". Big storm of the entire weekend was the near-severe winds and heavy rain storm at the airport Saturday evening.

  

Heavy Thunderstorm At Airport Last Evening And More

Mammatus at 5:50 am MST looking south from here.

Above is WRF-GFS radar forecast (from 06 UTC on the 11th) valid at 4:00 MST this early morning. Below is composite radar from 4:00 am this morning - reasonably good forecast that was just a bit under-done in coverage and a little fast in our area.

NWS composite radar chart for 5:00 am this morning - May 12th. The airport had a heavy thunderstorm last evening (7:35 pm) that produced wind gusts to 56 mph (just 2 kt shy of severe criteria), along with 1.10" of rain - huge event at TUS. nearby DM reported thunder with gusts to 53 mph, but only 0.06" of rain. Here at 5:00 am there was 0.10 in gauge, and it was raining lightly again - there was a rumble of thunder here last evening around 8:00 pm. Alert network (below for 24-hours ending at 5:00 am shows the generally light character of the precipitation, but with heavier amounts along south edges of metro area out to Three Points.

Finally two plots of CG flash density (from weather.bell and Vaisala) above is for 6-hours ending at 5:00 am, while below is 24-hours ending at 5:00 am. This has certainly been an active storm event for the Southwest, especially for May.

WRF-GFS Forecasts For Tomorrow (Sunday, May 12th)

Clear skies this morning - view above to south from Kitt Peak a bit after 7:00 am MST.

However, upper-level low is currently just west of northern Baja (image below from GOES-17 is upper-level water vapor at 1330 UTC this morning), and is still forecast to move across northern Sonora tomorrow.

The 06 UTC WRF-GFS forecasts from Atmo indicate two bands of showers and thunderstorms moving from the east to affect the metro area - first one around 4:00 am and then a stronger band during early afternoon. The forecast composite radar chart above is valid at 2:00 pm tomorrow. The 10-m wind forecast (below) is valid at 1:00 pm. The forecasts indicate a fairly strong outflow associated with the stronger band - this would move across metro area during early afternoon. The model run's forecast of total precipitation (second below, valid for period ending at 10:00 pm on 12th) reaches around 0.50", or bit more, for parts of metro, with 0.30" forecast for airport. Now it is just wait to see what tomorrow actually brings.

Very Quick Look At Weekend

Middle clouds with some buildups over Catalinas (above), but lots of blue out at Kitt Peak (below - both a bit before 7:30 am MST).

The GEFS plumes for QPF at TUS (above from 06 UTC) indicate best chances for showers and measurable rainfall on Saturday night into Sunday - amounts reach to over 0.30".

Above is WRF-GFS forecast (from 06 UTC last night) for sounding at TWC valid at 6:00 am Sunday morning - some CAPE, with PW values just below an inch. The 500 mb cyclone has gone into northern Sonora by that time, with easterly winds aloft here. Total rainfall forecast from this run below indicates nice precipitation event for southeast Arizona (forecast goes through 5:00 pm Sunday). Model forecasts 0.30" at the airport. So, for May, an interesting weekend ahead.

Unsettled Thru Weekend

Kitt Peak catching a bit of sunlight at 5:40 am MST this morning - (above, view is to the south). It was a beautiful morning to walk at sunrise, with clear and crisp conditions and no wind. The morning low temperature here at house hit 48 F.

The model forecasts are interesting this morning - particularly with their large large variance wrt moisture-related variables. The 06 UTC QPF plumes above from GEFS (above) all forecast light showers thru the weekend. However, timing and amounts are all over the place. The same forecasts of PW (below) exhibit much spaghetti after today and tomorrow. The operational forecast (blue) is actually 180 degrees out-of-phase with some of ensemble members.

The same forecasts for CAPE (above) are much more consistent with a distinct peak on Sunday the 12th (amounts though are pretty low). The GEFS 500 mb spaghetti plots below are distinctly stable through 12 UTC Saturday morning, showing almost no spaghetti on the large scale pattern forecasts. All of this just is reminder about how difficult the details of moisture forecasts are in some settings. 

Bit Dreary Again This Morning

Dreary skies this morning with high overcast - as per  Kitt Peak north view at 7:20 am MST. Yesterday was to a large degree clear, but became cloudy and overcast by late afternoon - campus views of Catalinas at bottom from 9:00 am and 5:00 pm.

Model forecasts are hinting at some chance for light showers by end of week into weekend. Plumes for QPF at TUS (above from 06 UTC forecasts) show this, although average (black) has been skewed some by several higher outliers. Same model plumes below for probability of rainfall at airport. Second below is from 00 UTC WRF-GFS and is forecast for total precipitation (on 5.4 km grid) through 5:00 pm next Monday the 13th. So, some slight hope for something more interesting by end of week.

Week Ahead

From Yosemite this morning, nice view of the falls (from Jack Hales webcam wall).

There is flat ridge over the Southwest currently, which will give us a very warm weekend. A trough sets up in the west early in the week and persists for 10 days or so. The GEFS averages for 500 mb show this  - above is 84-hours and below is 168-hours, both from 06 UTC runs last evening. While this looks like a promising pattern for precipitation, low-level winds stay westerly and dry during the period. Same run, but operational only (second below), shows precipitation through the week with the Southwest staying dry, but with storms mostly over California and the western mountains.

Looking at May precipitation here at house back to 2000, I find only 2 years with 0.25" plus - May 2005 was very unusual and an extreme outlier with 1.05". However, 15 of those years had less than 0.05". For my short period of record, May is far and away the driest month of year, as pre-monsoon, dry heat sets in.