Tuesday, March 31, 2020

Warm And Windy

Altocumulus overhead this morning a bit before 7:00 am MST.  At bottom is view of Superstition Mountains from Apache Junction at about 7:30 am.

IR satellite image from about 7:30 am shows thick, high clouds to our west and southwest, and these will be moving across southern Arizona later today and tonight. Forecast highs are in the 80s F through next Monday. But 06 UTC plumes from GEFS for wind speeds at 10m (below) indicate gusty winds most afternoons through first week of April.

Second below (from 00 UTC WRF-GFS) shows forecast of precipitation totals through 5:00 pm April 7th - most of Southwest remains dry through the period. It's been almost two weeks since last rain here at house, and ground is very dried out - time to water some of the yard plants.

Saturday, March 28, 2020

Clear And Very Cool Morning Here

Bright, clear skies above, a bit before sunrise this morning. This is a real contrast to yesterday afternoon (below) when skies were mostly cloudy with virga and some sprinkles. Midday sprinkles gave us a trace here, as per most of metro area. Temperatures in 50s, with winds of 20 to 30 mph made it, for here, a very raw day.

Low temperature this morning here at house reached 31F, making this the first below freezing morning since February 7th. But, we can now look forward to a serious warm up for the next seven or so days, with high temperatures up in the 80s. Second below is from 00 UTC WRF-GFS and is forecast of precipitation on 5.4 km grid through 5:00 pm MST on April 4rth.

Pre-sunrise images from the Mt. Lemmon SkyCenter Observatory - west of Summerhaven at an altitude a bit above 9,000 ft MSL. I particularly like the "unwrapped" version below.

Friday, March 27, 2020

Sprinkles Possible

Clouds this morning but with some bits of sunshine - above at 7:09 am MST.

Strong 500 mb short wave approaching Arizona this morning (12 UTC analysis above), but it remains moisture-starved. There are a few very light sprinkles/showers around this morning, but main impact will be gusty west winds this afternoon. See view from Kitt Peak this morning (bottom) that shows showers approaching from the west.

The 10-m wind plumes above are from the 06 UTC GEFS run. Winds below (from 06 UTC WRF-GFS run on 5.4 km grid) are valid at 2:00 pm this afternoon. Forecast indicates that the strongest winds will impact northern Mexico and New Mexico. Current NWS forecast for metro area indicates gusts as high as 28 mph for airport this afternoon.

Shown here are the WRF-GFS forecasts (on 1.8 km grid) for solar radiation today - both forecasts valid at 2:00 pm this afternoon. Outgoing long wave above shows low/middle clouds over eastern Pima Count, while incoming short wave is quite low. The clouds will diminish by evening, if WRF forecasts verify.

Thursday, March 26, 2020

Cloudy With Slight Chance Showers

High and middle-level clouds overhead this morning.

The 12 UTC forecasts from the WRF-RR indicate chance for light showers/sprinkles here today. Above is forecast for composite radar echoes at 2:00 pm this afternoon. Below shows total precipitation amounts forecast through 5:00 am MST tomorrow morning. Amounts are from a trace to very light totals, except for up in the Catalinas and Chiricahuas, where some amounts of half an inch or bit more are forecast. Looks like a slightly better event over to northeast in the New Mexico mountains.

The model forecast for winds this afternoon at 2:00 pm keeps the strong and gusty winds out of the metro area - which will be nice if forecast verifies.

The 06 UTC QPF forecast from 06 UTC GEFS models (below) show very slight amounts at the airport into April.

Wednesday, March 25, 2020

Chance For Sprinkles Tomorrow/Friday

View of East Mall at the University (from Jim Wyant's office) shows that it's nearly deserted at a bit before 7:30 am MST this morning.

A 500 mb short wave will swing across Arizona late tomorrow and Friday - forecast above from 06 UTC GFS is valid at noon on Friday the 27th. Below is the forecast of 850 mb winds and precipitable water valid at the same time. Narrow band of higher PW has already moved well south and east of our area, making for a very moisture-starved system.

Forecast above is for total precipitation through 5:00 pm on Friday, and below shows 09 UTC plumes for temperature at the airport (from SPC webpage). 

Basically the forecasts indicate periods of gusty winds (no graphics shown), with a chance for sprinkles and cooler temperatures tomorrow and Friday. Final system of month will come by at start of next week, but it will likely be another moisture-starved "event."

Monday, March 23, 2020

March Wind-ing Down

Chaotic skies this morning as we begin last full week of March.

Forecast above is GEFS average for 500 mb valid at 5:00 pm MST on Friday the 27th. Even though 500 mb trough persists over the West, most precipitation is forecast to remain north of our part of Arizona. Forecast below for total precipitation through 5:00 pm next Monday the 30th is from the 00 UTC WRF-GFS run at 00 UTC yesterday evening.

Second panel below (from the 06 UTC WRF-GFS forecast) is for 10m winds valid at 3:00 pm this afternoon.

Finally, two forecast from the GEFS forecasts at 00 UTC last evening. Wind forecast above indicates a windy week, except for tomorrow. Forecast below indicates a spike in PW at midweek, which may bring a chance for sprinkles or light showers.

Thursday, March 19, 2020

Widespread Rain Event Yesterday

Rains across the area yesterday occurred from around 3:00 pm MST into the early nighttime hours. Double rainbow above shot from here about 6:00 pm. At bottom is view of early morning blanket of snow at the Mt. Lemmon General Store (elevation over 7500 ft msl).

Gusty south-southwest winds yesterday afternoon gusted over 30 mph at many observation sites in southeastern Arizona. I noted gusts to about 70 mph at Kitt Peak.

I've broken the ALERT network reports into three sectors this morning, hoping to improve clarity of the data plots. Heaviest amounts fell in the northeast part of network - numerous reports over half an inch. Measured 0.58" here - March is turning out to be very wet month in my 20 years of record. Heaviest amount across ALERT system was 0.91 at the Oro Valley Water Plant.

At 500 mb (12 UTC plot above - note the large number of missing reports this morning) trough continues over the West and is forecast to continue for next week or so.

Even though the trough continues, little precipitation is forecast for the coming week (06 UTC QPF plumes above - temperatures below). After a cool cloudy day today, temperatures rebound quickly in the forecast through the weekend.

Wednesday, March 18, 2020

Clear This Morning - Showers By Afternoon

View at sunrise this morning with just a bit of scattered clouds. At bottom is view to southwest from Ensenada, Mexico (on Pacific Coast of northern Baja).

The 500 mb analysis at 12 UTC this morning (above) is much like the model predictions. Satellite image below (IR from 1205 UTC) shows a potent looking cloud pattern with the feature above - this will be our weather-majer later today.

Forecast of total precipitation (above from 06 UTC WRF-GFS) indicates 0.30" at airport, versus average from GEFS of 0.50". NWS forecast for airport today is at 100 percent POPS.

These two forecasts are also from 06 UTC WRF-GFS. Composite radar echo forecast (above for 3:00 pm MST this afternoon) indicates strong to severe thunderstorms moving across Pima and Santa Cruz Counties. Note that SPC outlook indicates isolated severe thunderstorms possible in our area.

SkewT forecast below indicates the severe storm potential - especially when one considers the vertical wind profile that has very strong southwesterly winds nearly to surface.

Should be an interesting day.