Thursday, May 30, 2019

More Re CG Lightning Flashes

Above shows detected CG flashes for 12-hours ending at 06 UTZ last night 9 (from and Vaisala). I noticed that there were a couple of flashes in northern Baja. Couldn't help wondering if the strikes occurred at the large wind farm near Tecate, Mexico (below).

Wednesday, May 29, 2019

Lightning Flash Density Past Week

May is going to come to a quiet end - although unusual cool has continued. Since the 21st six mornings brought low temperatures here at house down in the 40s. However, it looks like temperatures will be warming up as we begin June - NWS forecast indicates temperatures flirting with 100 F early next week here in Tucson.

The never-ending severe weather from the Plains to the East Coast has been the main story on national news for days now. I took a look at the CG flash density (from and Vaisala) for the past week ending at 7:00 am MST this morning. Plot above speaks for itself and is quite amazing.

Sunday, May 26, 2019

Gusty Winds Today - Red Flag Warning

This morning's wind profile for TWC (above, right side) indicates strong winds of 30 to 50 kts from just above surface to above 600 mb. The BL will be well-mixed to around 700 mb by mid-day, bringing another afternoon with gusty winds.

Once again, the NWS webpage shows conflicting graphics (I know I'm mostly wasting my time on this, since it appears that neither Region or Headquarters care about this problem). The two graphics above indicate that the Tucson metro area is under a red flag warning today (this means that conditions are critical should a wildfire develop). But the weather story cartoon below shows the real details, with the red flag area entirely to our east and south.

The rainfall outlook for rest of May remains dismal, as per 00 UTC WRF-GFS forecast for precipitation through 5:00 am MST on June 1st (below, on 5.4 km grid).

Saturday, May 25, 2019

More Wind For Last Week Of May

Nice view to west across Denver this morning, showing snow covered Rockies in distance (from Jack Hales webcam wall).

The 500 mb trough remains stuck over the West - above is this morning's 12 UTC forecast for 500 mb valid tomorrow morning at 12 UTC.  The trough continues to keep the subtropical ridge suppressed far to south over Mexico. Another dry short wave swings across Arizona tomorrow.

With the trough come more winds - just below is 06 UTC WRF-GFS forecast for 10-m winds valid at noon tomorrow. Second below is this morning's fire weather outlook from SPC, forecasting critical wildfire conditions over southeast Arizona and much of New Mexico for tomorrow. 

Will be good to get this unusual May behind us.

Thursday, May 23, 2019

Trough Persists In West Through End Of Month

Stratus hanging to Kitt Peak this morning.

A line of weak, sprinkle showers did cross metro area early this am - radar above from 3:00 am MST.

Only amounts of 0.04" in ALERT network (below for 24-hours ending at 7:00 am) were in and near the mountains. In the city DM had a trace; nothing here that I could detect.

Mean 500 mn trough persists across West for rest of month as per model forecasts. Above is valid at 5:00 am this morning and below valid at 5:00 pm on Saturday June 1st. May will definitely come in cooler than normal.

Wednesday, May 22, 2019

Strong 500 mb Short Wave Over Arizona Tonight

California 500 mb low this morning is forecast to move southeastward and sharpen-up considerably. The very moisture-starved system will move slowly across Arizona tonight. The 12 UTC NAM forecast above is for 500 mb, valid at 06 UTC tonight. The forecast models do hint that there might be just enough middle-level moisture ahead of the short wave to support some sprinkle showers this evening into the night; but basically a very marginal system, except for strong winds ahead of it. Wind forecasts from nighttime WRF forecasts remain similar to forecasts I posted yesterday.

David Blanchard sent two links to videos taken mid-morning Monday the 20th of a weak tornado (some refer to tornadoes of this character as "landspouts" because of their similarities to waterspouts, e.g. spinning up along a weak convergence line). This appears to have been the case with this brief tornado, southwest of Tuba City and north-northeast of Flagstaff along Highway 89. Image above by Shawn Williams and below from Matthew Harrison.

Tuesday, May 21, 2019

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.

Monday, May 20, 2019

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 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.

Wednesday, May 15, 2019

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.

Monday, May 13, 2019

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.


Sunday, May 12, 2019

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.

Saturday, May 11, 2019

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.