Forecast Discussion:

As the heat cranks up (we’ll talk about that in a moment) – smoke continues to be a problem. There are a number fires out across the southwest and they are making the sky hazy. We are missing the worst of it today (Figure 1).

Moisture is slowly increasing (and largely, it would be happening even if hurricane Bud hadn’t been a ‘thing’). Figure 2 shows the water vapor satellite image and there is Pacific moisture, gulf of California moisture, and Gulf of Mexico moisture finding its way towards us. We had severe thunderstorms out in the eastern Colorado (green arrows) fueled by this moisture.

Figure 3 shows that, before the weather changes this weekend, we approach 100F again. There will be a chance of afternoon thunderstorms around the state, but nothing severe is expected today.

Figure 1: The HRRR model forecast for smoke at all levels for Thursday afternoon. From
Figure 2: the water vapor satellite image from Wednesday PM. Reds/Oranges are dry air, greys/whites are moist air regions.
Figure 3: Forecast temperatures around 6pm Thursday.

The longer range forecast:

Tomorrow, the change begins.  A front pushes into the state.  That, plus the better moisture around, will make marginally severe weather conditions possible for NE Colorado.  This doesn’t include Longmont at this time (Figure 4).

The big news is the moisture from Bud.  Bud’s forecast is not towards southeast AZ (as it was yesterday) but is now towards extreme eastern New Mexico on a path towards Colorado (Figure 5). This is the circulation center. The GFS has the low center further north (northern New Mexico) for Saturday evening, with the bulk of moisture is ahead of the former tropical system’s center up into Colorado (Figure 6).

Figure 7 is a (probably over zealous) estimation of the rainfall for the next week. I’ve added the approximate locations of the four big fires. IF this verifies, this is over an inch of rainfall for all of the hot spots. The extreme rainfall in NE Colorado seems to come from a big thunderstorm complex, along a front, that invades the state on Monday into Tuesday. We’ll keep an eye on all of it. Longmont seems to pick up around 1 1/2 inches of rainfall over the next 8 days, from the GFS.

Figure 4: the day 3 SPC thunderstorm and severe weather forecast made Wednesday (valid Friday ).
Figure 5: The National Hurricane center prediction for the future 5 day position and strength of hurricane Bud. From
Figure 6: The future weather map from the GFS and valid Saturday PM.
Figure 7: total precipitation from the GFS between Wednesday and next Wednesday. and


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John Ensworth works from Longmont as the Principle Investigator for the NASA Science Mission Directorate Earth and space science education product review through the IGES (The Institute for Global Environmental Strategies – . He is in his 14th year running this review. He is an astronomer (from the 2nd grade onward) and became a meteorologist (in the 5th grade) when a thunderstorm in Arizona rained on his telescope when the weather service had only forecasted a 10% chance of rain. He has college degrees in physics and astronomy and climatology and a graduate degree in meteorology and earth science. He lectures at the Little Thompson Observatory in Berthoud, the Estes Park Memorial Observatory in Estes Park, and for a number of online universities. He built and runs a backyard observatory near Pace and 17th in northeast Longmont where he has lived for 8 years with his wife, daughter, son, and two cats. Invitations to open house nights at this observatory, LTO, and EPMO will be posted with future discussions when they are scheduled. Forecasting severe weather and snow amounts via text lead to this column. He began texting friends about the weather right after the September 2013 flood. The readers of this column will, hopefully, keep him honest in what he ‘thought’ he had forecasted for ‘the most recent’ storm.

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