DOW7 Deployed in Huntsville for IOP1

DOW7 is now deployed in Huntsville for OREO IOP1.

The weather is perfect right now.  Radar has shown a quasi-stationary precipitation cell immediately downstream over the Wasatch crest and over our area.  For a while, it was noticeably clearer west of the Wasatch from our vantage point.

This is just the sort of thing that we're looking for and trying to better understand. Very few studies have examined lee-side precipitation processes.

Lake Superior ship tracks

GOES-16

GOES-16 “Red” Visible (0.64 µm, left), Near-Infrared “Snow/Ice” (1.61 µm, center) and Shortwave Infrared (3.9 µm, right) images, with hourly surface wind barbs plotted in yellow [click to play animation]

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm) and Shortwave Infrared (3.9 µm) images (above) revealed the presence of ship tracks across Lake Superior on 16 November 2017. Aerosols from the exhaust of ships cause a “cloud seeding effect”, which results in a higher concentration of smaller cloud droplets compared to the surrounding unperturbed clouds. These smaller cloud droplets are more effective reflectors of sunlight, resulting in a brighter white signature on the Snow/Ice imagery and a warmer (darker gray) signature on the Shortwave Infrared imagery.

A view of the entire lake — using similar Visible, Snow/Ice and Shortwave Infrared images from the Terra MODIS instrument — is shown below. In addition to the ship tracks, plumes from power plants and/or industrial sites can be seen in southern Ontario, streaming southward near Thunder Bay (station identifier CYQT) and southwestward near Upsala (CWDV); another plume was evident in northeastern Wisconsin, to the southeast of Eagle River (KEGV).

Terra MODIS Visible (0.65 µm), Near-Infrared

Terra MODIS Visible (0.65 µm), Near-Infrared “Snow/Ice” (1.61 µm) and Shortwave Infrared (3.7 µm) images [click to enlarge]

OREO IOP1 Is ON!

It's great to finally have some weather again in northern Utah.  I was woken last night by strong southerly winds, and they appear to have transported in a pretty good plume of dust this morning. 

We have a team leaving the University of Utah today at noon to begin operations for the Outreach and Radar Education in Orography (OREO) Intensive Observing Period 1 (IOP1).  Every meteorological field program needs a good acronym (hence OREO) and we usually name each observing period as an "IOP."  IOP0 is typically used for a practice IOP, which we did about 10 days ago on Antelope Island.  Since then we've been waiting on weather.

We plan to operate this evening and tonight from a site just east of Huntsville to examine the spillover of precipitation across the northern Wasatch and into the Ogden Valley.   Already, there's some interesting things happening there.  Radar imagery very clearly shows echoes developing not on the windward side of the Wasatch, but downstream.  Much of this is just sprinkles or virga, but it is a hint that perhaps there is some sort of lee wave present at the moment. 


The HRRR forecast for 1Z (6 PM MST) is optimistic, with band of precipitaiton extending across central Nevada to the northern Wasatch.  The location and movement of that area of precipitation will partly dictate the success or failure of our mission tonight.  We're hoping it is in the right place at the right time. 


Tomorrow, we may be working on post-frontal snowshowers in northwesterly flow.  We have a couple of sites selected to operate out of, but will make final decisions in the morning with updated forecasts in hand.

Keep your fingers crossed!

Low Solar Radiation: Is That Why You are Depressed?

I can't tell you how many folks have emailed me or complained in person about what they perceive as a sudden turn to darkness.  They feel depressed, tired and anxious.  Daytime light helps maintain our circadian rhythms and a number of people suffer from Seasonal Affective Disorder (SAD) when the days grow short and clouds fill the sky.

So what is the truth?  How bad has it gotten?  Let's check. 

Here is the solar radiation reaching the surface in Seattle from the wonderful WSU AgWeaherNet collection of stations over the past six months (check below).   During June and July, some days had nearly 30 MegaJoules per square meter (a Joule is a unit of energy), and even cloudy days had about 15.  But recently, we have had days with 3-4 MegaJoules....way, way lower.   And the last few days, had no real spike upward in radiation to provide relief. 


Folks are right...it HAS been dark.   Part of the problem is, of course, the turn towards more clouds the last few weeks.   But, in addition, the number of hours of daylight has progressively dropped, something shown by the figure below (the vertical white line indicates today).   We have rapidly lost daytime hours the past few months and we are close to hitting bottom.


The recent switch to daylight savings time makes it even worse, with our commute home now in darkness.

The air even feels different, with biting cool, dampness that Seattle residents fear.   Here is the plot of relative humidity for the past 6 months at Seattle.  During the past month, relative humidity has jumped to around 80-90%, resulting in not only a feeling of dampness, but a loss of visibility due to fog and water-absorptive particles in the atmosphere.

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Very dark, clouds, humid, and cool---enough to scare off many Californians, and certainly able to explain the down feelings some folks have experienced during the past week.