National Weather Service Forecast Discussion

000
FXUS65 KBOU 260308
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
908 PM MDT Sun Jul 25 2021

.UPDATE...
Issued at 858 PM MDT Sun Jul 25 2021

Thunderstorms that produced the heavy rainfall in Boulder and
Jefferson counties earlier this evening the result to colliding
boundaries, and slow storm motions. Some lingering thunderstorms
over Park County this evening with some isolated rain showers over
southern portions of Jefferson, Douglas, Elbert and Lincoln
counties. Otherwise decreasing clouds overnight.

&&

.SHORT TERM...(This evening through Monday)
Issued at 224 PM MDT Sun Jul 25 2021

Convection is firing over Lincoln, Elbert and Washington Counties
at this time. There is also some developing over The best, along
a boundary over northeastern Lincoln County. r the mountains and
high valleys, mainly west of the divide. Dew point readings are
close to 70 degrees F over Phillips and Sedgwick COunties. Over
the rest of the plains and lower foothills, dew point readings are
mostly in the 50s F. On the satellite pictures you can see an
outflow boundary moving westward into the eastern border area of
the CWA right now.

The best CAPE is over the mountains west of the divide and over the
southeastern forecast area this evening,  This is currently where to
best radar echoes are.  Will hit the pops highest there early this
evening  The cells in the mountains are moving slowly southward.  On
the plains, the convection is moving slowly eastward.  There could
be flooding issues over he southeastern plains.  The cells over the
mountains should get as strong.  Monday looks a bit drier with
precipitable water values in the 0.50 to 1.00 range over the CWA.
The CAPE progs are pretty limited over the eastern plains, with
little to no CAPE over the rest of the plains, with the highest
values over the southwestern CWA.  Will hit the pops best there,
with little over the rest of the forecast area.  For temperatures,
Monday`s highs are 0.5 to 2.0 C warmer than today`s

.LONG TERM...(Monday night through Sunday)
Issued at 224 PM MDT Sun Jul 25 2021

Isolated thunderstorms in the central mountains and southern
plains may persist into Monday evening. There is good model
consensus through this week, as a large ridge will continue to
build and move slowly east over the CONUS. Heights will be rising
over Colorado through about mid week, with light subsidence, dry
air and warming aloft. Forecast soundings are showing an inversion
at around 500 mb through Wednesday, with 500 mb temperatures up
to around -2 C across much of the area. Precipitation will be
limited by the warm, dry air aloft but there should be enough
moisture below for some isolated storms and showers, mainly over
the high terrain. A warming trend will begin Monday with
temperatures forecast to reach 100 F across much of the plains by
Wednesday afternoon.

In the latter half of the week, Colorado should be on the west
side of the ridge with mid level moisture gradually returning to
the mountains in more southerly flow aloft. The warming trend
should break Thursday, though only slight cooling of a few degrees
is currently expected Thursday and Friday. Models are still
showing a weak, northeasterly front come across the plains late
Thursday or early Friday which may bring a bit more cooling and
slight increase of moisture, though these factors are uncertain.
Expect cooler temperatures and a significant increase in coverage
and intensity of storms and showers through the weekend.

&&

.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 858 PM MDT Sun Jul 25 2021

Normal drainage pattern overnight as the thunderstorms have
diminished. VFR tonight and Monday.

&&

.HYDROLOGY...
Issued at 858 PM MDT Sun Jul 25 2021

The flash flood threat looks very low on Monday. The showers and
thunderstorms over the plains could produce some heavy rainfall
amounts as they are barely moving.

The coming week looks pretty dry through Wednesday, with only
isolated thunderstorms over the mountains and mainly away from the
new burn areas. Any storms that form will be slow moving, but the
flood potential will be very low through Wednesday. Some increase
in moisture is expected for the weekend, and the environment will
still support slow moving storms with potential for heavy rain.
An elevated risk of burn area flash flooding currently seems
likely for next weekend.

&&

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

$$

UPDATE...Cooper
SHORT TERM...RJK
LONG TERM....EJD
AVIATION...Cooper
HYDROLOGY....RJK/EJD

NWS BOU Office Area Forecast Discussion