Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 020113

Area Forecast Discussion
National Weather Service Denver/Boulder CO
713 PM MDT Sat Oct 1 2022

Issued at 710 PM MDT Sat Oct 1 2022

Updated to decrease PoPs and to remove the mention of showers and
thunderstorms from the forecast along the Front Range. Radar and
satellite show clearing over the area and off to the west. Latest
short term models now showing a quiet night as well. With some
clearing, will need to monitor the chance for fog. Plan on holding
off from mention fog at this time. For the plains, the convection
will continue to shift northeast through the evening and should be
done by midnight. The next wave moves into Colorado overnight and
clouds should return after midnight with showers possible by
Sunday morning.


.SHORT TERM...(This evening through Sunday)
Issued at 232 PM MDT Sat Oct 1 2022

Showers and thunderstorms have gradually increased in coverage
and intensity early this afternoon, and activity should continue
to increase through the early evening hours. Upstream observations
across the mountains suggest that snow levels have dropped as low
as 10-10.5kft with the main convective line, and slushy
accumulations will be possible across some of the higher peaks.
For the plains, guidance has remained fairly consistent with the
ongoing convection, which should spread into the I-25 corridor by
3-5 PM and slowly drift east through the evening. SPC Mesoanalysis
shows as much as 500 MLCAPE along and east of I-25 with 30-35kt
deep layer shear, which should support a few storms with small
hail and gusty winds. There is still some uncertainty in the
overall convective evolution, but I have better confidence in
storms today compared to yesterday. Showers and an isolated storm
will linger overnight, with moist southwesterly flow aloft and
modest QG ascent remaining in place.

The upper level low to our northwest will slowly retreat towards
Montana on Sunday, as we slowly (very, very slowly) begin to trend
towards a drier pattern... though that won`t truly arrive until
next week (see the Long Term below for details). Scattered showers
and storms are forecast again Sunday as moist southwesterly flow
persists. There isn`t as much instability or upper support
tomorrow, so less coverage is anticipated across the plains, but
at least a few showers/storms appear likely. Temperatures should
be similar to today.

.LONG TERM...(Sunday night through Saturday)
Issued at 232 PM MDT Sat Oct 1 2022

A few changes in the long term forecast as an upper level low
continues to slowly hover our the Central Plains. This pattern will
provide ample amounts of moisture and lift to increase
precipitation chances across the CWA. Overall in the long term
forecast, temperatures continue to trend slightly below normal.

Starting Monday afternoon, progressive storm motion should keep the
burn areas at a low limited threat of flash flooding. 700mb vertical
velocity values reaching 30-45 DEA/s should support showers and
storms crossing over to the plains from the higher terrain. Weak
low level winds and moist mid levels of 60-80% RH support small
hail for parts of the foothills, urban corridor and plains. Higher
MUCAPE values near 400-500 J/kg in the northeastern corner will
keep storms lingering Monday evening through the overnight hours
into Tuesday morning.

Drier air begins to enter the 500mb levels across the Front Range
Tuesday afternoon shown on GFS RH cross sections. This may limit
storm development and MLCAPE values are near 100-200 thus decided to
decrease NBM PoPs for the foothills and Palmer Divide. Clouds will
linger into Wednesday morning. Most of the region will likely trend
under partly cloudy skies and dry conditions Wednesday afternoon.

Northwesterly flow will occur Thursday afternoon as upper levels
begin to shift. An upper level ridge will replace the trough axis
starting Wednesday evening into Thursday morning. A few shortwaves
may provide enough moisture Friday into next weekend but chances
remain low especially with drier air entering 500-700mb. There is
model disagreement on precipitation chances but surface
temperatures remain slightly below or near normal through the
weekend for all areas.


.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 603 PM MDT Sat Oct 1 2022

Showers and thunderstorms have moved off to the east of the
Denver area. Radar and satellite not showing much activity off to
the west across central and western Colorado. Expect a quiet night
with sct/bkn mid to high clouds. NAMNest shows low clouds and a
little fog 08-15Z. Can`t be ruled out with some clearing taking
place and the recent rainfall. Though agree with the other models
that increasing clouds after midnight should prevent fog
development. Around round of showers is expected Sunday, which
may begin in the morning. Better chance will be during the
afternoon when the airmass becomes unstable, could see a weak
storm after 20Z as well.


Issued at 232 PM MDT Sat Oct 1 2022

A limited threat of burn area flash flooding will continue into
Sunday with a few rounds of showers and thunderstorms. The overall
threat should decrease a bit Sunday as instability and moisture
decrease slightly.

Scattered showers and storms will develop in the mountains and
valleys Monday afternoon where PWATs are reaching 0.5 inches.
This will bring a limited flash flood threat to the burn area.
Showers become more isolated and weaker Tuesday and Wednesday.




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