Tuesday, March 28, 2017

Early Morning Showers


Guess I was distracted by Al running around at University of Oklahoma yesterday. Turns out that a couple of ensemble member forecasts got the very low POPs event of early this morning. Regional radar above is from 03:00 am MST. Airport and DM had thunderstorms in addition to the light showers. TUS reported 0.21" and DM had 0.11", while we had 0.06" here at house.

The 06 UTC WRF-GFS caught up with what was happening and its forecast for 04:00 am is below - but of course by the time that forecast ran, the showers were moving into the metro area. The atmosphere out-performed the models this time around.



Portion of ALERT network shown above is 6-hour precipitation ending at 06:00 am this morning - rainfall mostly centered over core metro area, with amounts generally less than a tenth of an inch. 

The showers mainly cleaned out most of the dust and pollen, so that it was a beautiful early morning with clean and sparkling skies - below.




Monday, March 27, 2017

Roker Does Football Stadium Weather


Al Roker did his morning US forecast from the University of Oklahoma football stadium. He's preparing above with band members, and then does a weather-run-around with the band providing the background graphics. Guess some could argue that this is a better use of the stadium than are the University's professional football games.


Locally, best chances rest of month are for some windy afternoons. Below is 06 UTC WRF-GFS forecast of total precipitation through 11:00 am MST on March 30th. However, a few ensemble members continue to forecast slight chances for some light showers before April arrives.




Friday, March 24, 2017

Precipitation Here Before End Of Month?


The forecast runs from 00 UTC last evening are holding out a slight bit of hope for some precipitation here before March comes to an end. The GEFS plumes are shown above, while the WRF-GFS forecast of total precipitation (below on the 5.4 km grid) goes out through 05:00 pm MST on the 31st. 

The big centers of action are northern California, Colorado, and the Southern Plains. Down here we're along the fringe of the active pattern and will have to watch how things evolve.




Thursday, March 23, 2017

Cooler Today With Wind And Some Dust


Another event fizzles out with respect to precipitation - this has been the pattern for last three systems or so. Looks pretty good in model forecasts at longer time frames and then gets drier and drier in the shorter range forecasts. The 12 UTC WRF forecast from yesterday for entire "event" proved pretty good. Basically zero POPs observed across the metro area.


Above graphic (from weathergraphics.com and Vaisala) shows CG flash density for past 48 hours. Considerable lightning west to north and one thunderstorm at north end of the Santa Rita Mountains. A station at Corona had 0.07" - pretty much the big event locally. Map below from MesoWest shows 24 hour precip reports of mostly zero in eastern Pima County. Two very slight sprinkles this morning here, but mostly afternoon winds of 30 to 40 mph and some blowing dust. 

There will be a couple of more systems before the month ends but remains to be seen whether one of them will actually bring a rain event.

The cooler temperatures are are a nice change.




Wednesday, March 22, 2017

Another Moisture Starved Weather System


As was the case with the last few systems, the forecast models have trended drier as this event neared in time. The plumes from the SREF system above are from the SPC and are for the 09 UTC run valid for TUS. The mean (black) is only 0.04" (vertical scale shown in increments of 0.025" - thus the second highest airport amount shown by green line is just 0.10").

For unknown reasons the MIMIC PW and the GEFS plumes have not been available since 12 UTC Monday morning this week.

The forecast below shows total precipitation forecast by the WRF-GFS at Atmo for period from 06 UTC last night through 11:00 pm MST tomorrow night. Almost a total miss for southern Arizona in the current model forecast. The forecast soundings still indicate a chance for shallow showers with the cold front, centered around 02:00 am early tomorrow, indicating a bit of hope remaining.

Bottom image shows a bit of early morning color on our placita.






Monday, March 20, 2017

Showers Possible Wednesday Night In Metro Area


Models forecast the possiblity of a moisture-starved event on Wednesday night as a rapidly weakening AR affects southern Arizona. The 00 UTC 20 March QPF plumes for TUS are shown above (from the GEFS). The operational GFS (blue) was one of the wettest forecasts at 00 UTC. The GEFS forecasts 100 % POPs for the airport Wednesday night into Thursday morning - current NWS forecast bit more conservative at 40%. Remember that the grid point forecasts used to extrapolate the GEFS to TUS are a fair ways off and all at higher elevations than the airport. For comparison the plumes from about the same lead time for the February 28th "event" are shown down at the bottom.


The 00 UTC WRF-GFS forecast from Atmo for total precipitation through 05:00 pm MST on Thursday (above) avoids the airport. However, the forecast sounding for TUS below is valid at 02:00 am on Thursday and shows some threat of showers or thunder during the night. The 06 UTC runs have become somewhat drier than were the 00 UTC forecasts.

So another iffy situation for us to watch.





Sunday, March 19, 2017

Wildfire Just West Of Boulder

Another day here with high temperatures above 90 F - enough is enough.


Wildfire burning this afternoon in Sunshine Canyon just to west of Boulder. More than a 1,000 homes have been evacuated today. Much snow in high country but Plains and Foothills very dry with gusty winds.