Longmont, Colorado 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

220
FXUS65 KBOU 202025
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
225 PM MDT Sun Jul 20 2025

.KEY MESSAGES...

- Slightly warmer with less thunderstorm coverage today.

- Increased moisture and slight cooling expected by midweek.

- Warmer again for next weekend.

&&

.DISCUSSION /Through Sunday/...
Issued at 205 PM MDT Sun Jul 20 2025

Water vapor imagery shows drier conditions in place across the
forecast area this morning compared to Saturday, and the upper-level
high remains centered over OK. A ribbon of higher moisture
associated with a remnant MCC over southern New Mexico is visible
wrapping around the southwesterly flow aloft and approaching SW
Colorado. Some of the hi-res models show this moisture making it
into western CO, bringing late night/early morning shower potential
to our northern mountains. With a trough entering the Pacific
Northwest, there is a chance this moisture gets pushed slightly
more southward, but have increase PoPs slightly over the northern
mountains to account or this potential.

There are no significant changes for today`s forecast as the
drier conditions will result in less shower and storm coverage
this afternoon and evening, with the plains largely remaining dry.
There could be some gusty outflows from passing virga showers,
but generally the moisture will be over the central and southern
mountains and foothills, as well as the Palmer Divide and adjacent
plains. Hi-res guidance show a dryline in place along the eastern
edge of the forecast area that could help initiate storms later
today, with a few stronger ones possible for Lincoln and southern
Washington Counties into the evening.

The synoptic pattern will remain largely dominated by the broad
upper-level ridge over the south central US through the forecast
period, with a few shortwave passages over the northern tier of the
US. Ensembles still show a steady increase in moisture for the
first half of the week, with Wednesday seeing the peak as PWAT
values reach 130-160% of normal. Scattered afternoon showers and
storms are expected Monday and Tuesday with slightly higher
chances for some moisture making it onto the lower elevations.
Slightly cooler 700 mb temperatures are expected on Wednesday and
Thursday associated with a cool front that will give the plains a
brief break from afternoon highs in the 90s. With the increased
moisture and light winds under the ridge, there will be increased
potential for localized flooding under some heavier rainfall.
A warmup still looks to start on Friday making for another hot
weekend, as ensembles continue to show temps nearing triple
digits across the lower elevations.

&&

.AVIATION /18Z TAFS through 18Z Monday/...
Issued at 1123 AM MDT Sun Jul 20 2025

VFR conditions expected through the TAF period. Drier conditions
are in place today with large dewpoint depressions. Afternoon
showers and storms are anticipated to develop mostly west and
south of the TAF sites where instability is greatest, but some
passing high-based virga showers will be possible for all TAF
locations. ACARS soundings show DCAPE surpassing 1000 J/kg this
morning, which is sufficient for gusty winds from passing virga
showers to develop. Guidance suggests easterly winds will make a
westerly shift between 23-0Z at all TAF sites. A few stronger
storms are possible southeast of the TAF sites later tonight that
could produce a few wind shifts as outflows push westward across
the plains.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Bonner
AVIATION...Bonner