Boulder, Colorado Weather: 7/26/18

Yesterday was rainy and stormy off and on all afternoon and evening. I got rained on heavily when walking back to the apartment at 2:00 AM.

This morning has been mostly sunny, warm and still.

The NWS in Boulder, CO, forecasts a mostly sunny day, with a 60% chance of showers and thunderstorms, and a high temperature of 79 F.  The winds will be light and variable, becoming east at 6 mph in the afternoon.  This evening will be mostly cloudy, with a 50% chance of showers and thunderstorms, and a low temperature of 57 F.  The winds will be from the east at 6 mph, becoming light and variable.

The NWS has issued a Hazardous Weather Outlook concerning scattered showers and thunderstorms this afternoon.  Storms could become severe, with heavy downpours, ping pong ball sized hail, and gusts to 70 mph.

The Storm Prediction Center (SPC) has issued a Slight Risk for severe weather today.  The primary threats will be hail and severe wind gusts. The Marginal Risk area includes the Denver Metro area.

Associated with the Slight Risk is a 2% Tornado Threat Ring.

The visible satellite image shows light cloud streaks over the mountains, and a cumulus field in the eastern part of the state.

The 12 Z upper air sounding from Boulder shows a nearly-saturated atmosphere, all the way to 200 mb.  There was 1.08 inches of precipitable water present in the column.  There was 910 J/kg of Convective Available Potential Energy (CAPE) and -25 J/kg of Convective Inhibition (CINH).  The Lifted Condensation Level (LCL) was 101 m.  There was a tiny thermal inversion near the surface, and the 0-3 km average lapse rate was 5.5 C/km.

The hodograph shows that there was 5 kts low-level shear (due mostly to directional changes) and 36 kts deep-layer shear (due mostly to speed changes).


The surface observations (from the SPC Mesoscale Analysis Map) show warm temperatures and moderate humidity, based on the dewpoints.   The skies are clear and sunny over most of the state.  The winds are still over most of the state.

The surface pressure chart shows that there is high pressure over southern Colorado today, but that there are no strong pressure gradients over the state this morning.   The RAP shows that the pressure will drop with diurnal heating, and a light west to east pressure gradient will form in the next six hours.

The NAM 250 mb chart shows moderate, zonal flow over the state today.

The HRRR simulated reflectivity shows a few pockets of precipitation by 21 Z.  One of them has a helicity track and is very near Boulder.  I will be watching to see if this verifies.

The HRRR predicts that the high temperatures for Boulder will peak in the upper 80’s F by 22 Z.

The HRRR dewpoints will remain high all day, reaching the mid 50’s F near Denver.

The HRRR shows no significant gusts.  This image has been excluded from today’s post.

The HRRR supercell parameter shows a non-zero value over Boulder by 21 Z.

The NAM shows skies will show a few clouds, but perhaps not enough to block this evening’s telescope observations.  The clouds will clear through the observation window.



The HRRR actually shows a few more clouds, but probably not enough to block observations tonight.


I am watching the supercell potential closely today.  I have quite a few things to do today, so I won’t be able to chase, though there may be a cell develop nearby.

Thank you for reading my post.

The forecasts from the National Weather Service are from The NWS Homepage
The upper air soundings and mesoscale analysis plots are from the Storm Prediction Center website.
The satellite data, model data, and forecasted soundings are from College of DuPage – SATRAD

About highplainschasing

This blog is about my tales in storm chasing. My name is Seth Price and I am an instrumentation instructor at New Mexico Tech. My amateur radio call sign is N3MRA.
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