Thursday, January 31, 2019

Quick Look At Shower Situation

Northwest view from LAX this morning - dreary, dark with light rain.

Below shows NCAR RAP 500 mb analysis for 12 UTC this morning. The small cyclone west of California continues to move south-southeastward along the coast. Associated rainfall has been expanding and now now extends fro LA Basin northward into central Valley.

The WRF model forecasts have tended toward a slightly more damp event (amounts here and there in Pimas County of Trace to a tenth of an inch). The timing of the short event has also been forecast to shift more into the day tomorrow. Forecast QPF plumes for TUS from the 15 UTC run of the SREF models are shown above. Amounts remain small and timing is spread through day tomorrow.

The satellite image below (from GOES 17) is for middle level WV (band 9) at 17 UTC. The very dry air wrapping around the low may well play a role in keeping amounts light here.

Still watching.

Wednesday, January 30, 2019

Showers Tomorrow Night?

Still snowing in Kalamazoo, Michigan this morning, and still Christmas in Alpine, Wyoming (north of Star Valley Ranch).

This morning there is a weak, and small, mid-upper level closed low well west-northwest of San Francisco (captured above in 14 UTC IR image from GOES-17). This system is forecast to weaken further as it moves across Arizona late tomorrow. 

Models have some disagreement among them. The plumes from the 06 UTC GEFS forecasts indicate some chances of showers tomorrow night at airport, with amounts from Trace to about a tenth of an inch. Meanwhile, the various WRF, high-resolution forecasts available this morning from Atmo keep this system moisture-starved with no precipitation for southern Arizona through mid-day Saturday (below is GFS version from 06 UTC).

Will keep watching.

Tuesday, January 29, 2019

Quick Update Tuesday 29 January

Western Michigan University (Kalamazoo)  looks about the same this morning as it did yesterday - though snowfall appears a bit lighter today.

Below is this morning's forecast for Madison, Wisconsin - very ugly forecast; glad we're in Arizona!

As national news emphasizes, the major portion of the 500 mb polar vortex has slipped southward toward the Great Lakes. This morning's 12 UTC analysis above from SPC - note the very cold temperatures in core of cyclone are -45 C and colder.

Below is this morning's 06 UTC GEFS plumes for TUS QPF. The ensemble members are fairly consistent, forecasting light rainfall at the airport Thursday night. After that there is much variance among the various members, with main consensus being a continuing chance for showers during the first week of February.

Monday, January 28, 2019

Chance For Precipitation Event(s) To Begin February

First - cold low temperatures here for last seven days (including this morning). Each morning has been 32F or colder during past week, with four mornings down into mid-upper 20s F.

Snow storm moves across Great Lakes region today, prior to mid-week plunge of very cold arctic air into north-central U.S. View above shows moderate snow falling at Western Michigan University.

The 06 UTC GEFS average 500 mb height forecasts (above valid at 12 UTC this morning and below valid  00 UTC 3 February show a substantial pattern change by end of month. The intense 500 mb ridge along west coast shifts westward and southward, as a trough breaks through and under ridge. This shift brings troughing to west coast - at least for a few days.

This pattern change brings chances of precipitation to the Southwest - last significant precipitation here at house was 0.85" on January 6th. Plumes from the 06 UTC GEFS forecasts show: above chances for two rain events at TUS on the 1st and again around the 3rd; and below plumes for PW indicate gradual increase through the week and then a plunge back to dry conditions on the 3rd. Finally something to watch!

Tuesday, January 22, 2019

Cold Mornings And Warming Afternoons This Week

Quick recap of yesterday's winds: Most ASOS stations in northern Arizona reported gusts over 40 mph yesterday, with Winslow the highest at 64 mph. In southeastern Arizona the only ASOS observation of over 40 mph I found was at Pioneer Airfield (gusts to 41 mph). The RAWS sites at Guthrie (48 mph) and at Hachita Valley (62 mph) were only sites I found over 40 mph. Hachita Valley is in the New Mexico Bootheel.

The forecasts here the GEFS mean 500 mb charts: above is 84-h valid at 12 UTC on 25 January, while below is for 168-h valid at 00 UTC on 25 January. Strong ridge continues along the West Coast on North America north to Alaska, while cold trough persists over the eastern U.S.

Forecast at bottom is total precipitation forecast through 00 UTC on 30 January from the 00 UTC WRF-GFS run at Atmo. Dryness here in Southwest continues, perhaps through end of month.

Monday, January 21, 2019

Wind Main Weather Event For Southeast Arizona This Week

First, a drone photo (from November 10th) of his place in Ash Canyon south of Sierra Vista. View is looking basically toward the west - I think top right is Miller Peak at 9470 ft MSL.

This morning there is a strong, 500 mb short wave over the Great Basin that is moving rapidly eastward (analysis above for 12 UTC from SPC - note, whose staff are working without pay during this miserable, government shutdown). The 06 UTC WRF-GFS 500 mb forecast (below) is valid at midnight tonight and indicates by that time the short wave will be be strung out from central South Dakota back south-southwestward to eastern Arizona. Very cold middle-level temperatures will be moving across the state with this system (-20 to -30 C).

The GEFS plumes from 06 YTC for TUS (above for T and below for wind) forecast marked cooling for tonight and tomorrow, followed by a rapid warm-up for rest of week. The wind forecast indicates indicates strong winds today with the system. At bottom is 06 UTC WRF-GFS forecast of winds valid at 3:00 pm MST this afternoon. 

So it looks like the system coming rapidly by will be the main weather event for the week.

Saturday, January 19, 2019

Very Cold Upper Midwest

Not much change locally. But as large storm heads toward the Northeast, very frigid arctic air has intruded into north-central U.S.

View above is from Duluth, Minnesota, this morning. Below is 1323 UTC surface plot for North Central U.S. Note the very cold temperatures west and north of Lake Superior. Temperatures down to below -30 F in northern Minnesota, and in southern Canada some stations were reporting colder than -40 F. Coldest outbreak that I can remember in quite some time.

Wednesday, January 16, 2019

Fast-Moving 500 mb Short Waves Much Of Coming Week

Skies have cleared in our area at sunrise today - north view from Kitt Peak above at 7:00 am MST.

I have grabbed three forecasts (500 mb and Surface) from the 00 UTC run of the ECMWF. The valid times of the charts shown here are: 00 UTC 19 January; 00 UTC 21 January (middle); and 00 UTC 25 January (bottom). The West Coast ridge intensifies, then weakens as a short wave breaks through, and then becomes very strong by end of next week. Significant storms occur during this 216-hour period for the Northwest (early), then two significant snow storms are forecast for Plains, Midwest, and East Coast for rest of period. We are brushed by the the western portions of two short waves - bringing perhaps more chances for sprinkle-showers in eastern Pima County.

Monday, January 14, 2019

Continued Bit Unsettled For Coming Week

Trough in southern stream continues along California coast (IR image above from 1330 UTC), as new week begins. Another weak piece breaks off into Southwest, bring a slight chance of light showers tomorrow and tomorrow night (only 0.02" here from yesterday's "event"). Perhaps another chance toward the weekend. Note the streams of high clouds over Arizona from low latitudes - cloudiness kept lows this morning quite mild (42 F here).

Some images here from Jack Hales' webcam wall. Coming up the Pacific coast near sunrise this morning. Below - really humongous cruise ship squeezing through Panama Canal (note the really ugly black smoke - haven't seen black smoke for very long time!); middle - sunrise from Cabo San Lucas; - and LAX this early am.

Sunday, January 13, 2019

Mystery At Arch Solved

In a previous post, I thought this looked like a man sitting on bench looking across the river at the Gateway Arch. Decided it was a "structure" since it was still there the next morning. He's still there and looks more like a person at noon today.

Katie did a bit of sleuthing and discovered that he's a statue, as per below. 

Quick Update Sunday Morning

Light showers are moving across metro area early this morning (radar above from 6:30 am MST).

Some ALERT sites have received more than 0.04" during six hours ending at 6:00 am (just below). While there has been light snow up on Mt. Lemmon - at bottom is General Store parking lot in Summerhaven also at 6:00 am.

Saturday, January 12, 2019

Chance For More Sprinkle Showers

Storm over central U.S. is slowly moving toward the east this morning. Views here are of the Gateway Arch in St. Louis from east side of Mississippi River. Yesterday afternoon there was moderate snow, while this morning (below) clouds have lifted, some showing a significant amount of new snow. While it appears to be man sitting in the enclosure, it is apparently a structural feature.

This morning's 500 mb analysis (from SPC above) shows a trough along the California coast this morning. The southern portion is forecast to break off and come east under the very strong blocking high over northern Idaho. This feature is forecast to weaken rapidly as it comes across Arizona tonight. The forecast 500 mb chart below is valid at midnight tonight (from the 06 UTC WRF-GFS forecast at Atmo). At bottom is same model run's forecast of total precipitation through noon tomorrow - certainly nothing like last weekend's event.

Friday, January 11, 2019

Minimal Event Yesterday Morning

Light showers left 0.04" here and at several sites in northern metro yesterday morning. Was mostly a cloudy and mild day.

Large scale patterns continue to have little predictability beyond a couple of days - as illustrated by 11 January 06 UTC GEFS plumes for QPF above and below PW at TUS.

Most weather interest will continue to be focused on central and eastern U.S. for at least the next week. Warmer and more sunshine here locally, with bit of chance for more light showers tomorrow night.

Thursday, January 10, 2019

More Light Showers

I have an appointment on east side in just a bit, but here's a quick update.

View from campus above is at 8:41 am MST, just after light showers moved past here. Radar below is from 7:25 am. Showers this morning are actually producing some measurable amounts, as opposed to yesterday's light sprinkles (Trace here yesterday). This morning there is 0.03" in gauge, and I see TUS reported 0.02".