1-Minute Satellite Imagery Where Radar Data is Poor

We are watching the Pendleton, Oregon (PDT) CWA this afternoon waiting for more thunderstorms to develop. I am finding that the 1-minute satellite imagery is useful where radar data coverage is poor, especially out west.

Watching for convection on the 1-minute satellite data out west

Our CWA outlined in white with the radar coverage mapping. Shows a void in radar data across the southern part of our CWA.

-BW

CI Even With Thin Middle To High Clouds - CI Is Occurring!

The CI and GOES-15 visible image in the upper right shows a cursor readout with a 15% CI probability at 2030 UTC just southwest of the Pendleton, OR CWA. This was occurring, despite some relatively thin middle to high clouds moving through the area. This would suggest that the CI value would be much higher, if the middle to high clouds were not present.

Below is the 1-minute SRSOR imagery with this developing cell at 2030 UTC. The imagery clearly showed a robust updraft developing.

The MRMS 0.5km MSL Composite Reflectivity radar image below (upper left image) at 2030 UTC showed this cell indeed had risen above the 35 dBZ threshold (46.5 dBZ in the composite reflectivity). Thus, this cell would likely have had a higher CI without the thinner middle to high clouds present. JJW

Sierra Nevada MCV

GOES SRSOR vapor channel showing distinct twist over the central Sierra's this afternoon as shown in the image animation below.

GOES 14 SRSOR Water Vapor Animation

Image below shows convection associated with this feature over the central Sierra's and just east of Lake Tahoe.

2054Z Composite Reflectivity

Tornadotod

CI Product Stuggling With Thicker Middle To High Clouds Over Area.

The Pendleton, OR radar image below shows cells developing across the northwestern part of their CWA. The cursor readout shows a developing cell in north central Klickitat County at 2035 UTC.

The CI and GOES-15 visible imagery in the upper left shows little to no CI probabilities in that area. Interestingly, the cursor readout below shows a small pink area in the same spot as the developing cell above. The pink depicts the snow mask, so I'm not sure why the CI product thinks it is part of the snow mask. Overall, the CI product is struggling to locate these developing cells, likely due to the thick middle to high clouds moving through the area. JJW

Radar Coverage is a Challenging Problem Out West

Due to the varying terrain in the western U.S. there are many data gaps in radar coverage. Luckily...1-minute SRSOR Visible imagery is available and will add great value in situational awareness this afternoon.

Base Reflectivity (LEFT) and MRMS Radar Quality Index (1.0 - Best, 0.0 - Worst) (RIGHT)

1-minute SRSOR Visible Imagery with CI algorithm and ENI Total Lightning overlaid.

~Lilly Miller~

Mesoscale update 2 BOI

19Z GOES LAP shows instability building through the Snake River Valley and northward into the Salmon mountains.  20Z GOES SRSOR visible imagery shows an area of expanding cumulus moving northward out of north central Nevada and expect high based convection will develop by 21Z.  Broad based surface dewpoint depressions suggest more vigorous convection will pose a dry microburst wind threat and potential hail threat over northern counties where low level moisture is maximized.  Will continue to monitor...

19Z GOES LAP/20Z GOES Vis

Tornadotod

GOES SRSOR cloud tracer

18Z GOES derived winds denote a lack of low level winds through north central NV.  However GOES SRSOR visible imagery aides in tracking cumulus clouds through northern NV and gives a sense of the speed and direction of the flow in an otherwise data void area.

18Z GOES Satellite Derived Winds

1838-1927Z GOES SRSOR Loop
(note the movement of developing cumulus over north central Nevada)

Tornadotod

LAP Layer PW Showing Gradient Over Pendleton, OR CWA.

The 4 panel LAP layer PW product below is showing a gradient of PW at all layers. The upper left image shows the total PW, with the cursor readout within the Pendleton, OR CWA. This gradient of PW runs from northeast to southwest across a good portion of the area. This may be an area to watch for convective development this afternoon. In addition, the upper right image shows the 700 mb to 300 mb layer PW. This will need to be watched as well, to see if the drier air to the southeast shifts into the area. This would indicate drying aloft and possibly steeper lapse rates and increased instability. JJW

LAP CAPE Showing Spots Of Data Within GFS-Dominated Sampling Area.

The upper left image below shows LAP CAPE values in spots across the Pendleton, OR CWA at 1700 UTC. The cursor readout shows spotty values ranging from about 300 J/kg to 750 J/kg. The LI values ranged from -1 to -3 as well in these spots. These were in spots that mainly had cloudy sky sampling. The GFS sampling did not show any CAPE and positive LI values, which seems to be underestimating (again).

The modified 1200 UTC sounding below from Boise, ID shows CAPE values around 860 J/kg. This was adjusted for surface and low level temperature and dew point temperature profiles around 1800 UTC in north central portions of the Pendleton, OR CWA. The 860 J/kg may be overdone somewhat, as the low levels of the sounding may need further refinement as the afternoon progresses. Still, the LAP CAPEs of 300 J/kg to 750 J/kg in the small points across the area seem reasonable, compared to the 1200 UTC Boise ID modified sounding. I would be more confident to assume that the LAP CAPE values were located across a good portion of the forecast area. JJW

Environment for Thunderstorm Development (PDT CWA)

Checking the environment today, it does look like we will see some scattered afternoon and evening thunderstorms.

We are seeing a lot of GFS panels in the LAP product today, but with some satellite inferred as well.

There is a swath of enhanced CAPE, LI, and PW stretching from the southwest part of the CWA around the Cascade Mountains up to the northeast corner.

It will be interesting to watch how things pan out today and if anything turns severe.

-BW