Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 262042

Area Forecast Discussion
National Weather Service Pueblo CO
242 PM MDT Tue Sep 26 2017

.SHORT TERM...(This evening through Wednesday)
Issued at 241 PM MDT Tue Sep 26 2017

...Another Batch of Moisture Headed this Way...

Satellite pictures this afternoon show circulation around an upper
low pressure area over Arizona, starting to pull moisture into
Colorado from the south.  This moistening trend will continue
overnight as a bit of subtropical moisture gets caught up in the
flow and surges north into the state.  Moisture and precipitation
will increase over the western mountains and San Luis Valley
overnight and then spread eastward across the I-25 corridor
Wednesday morning.  Some of the moisture and precipitation will try
to work east of the I-25 corridor in the afternoon.  However, it
looks like precipitation amounts east of the corridor will be
lighter and much more scattered than areas farther west during the
day Wednesday.

Snow levels will likely remain generally above 10,000 feet through
Wednesday.  Local lowering of the snow level to around 8,000 feet
will be possible at times late tonight and Wednesday in areas of
heavier precipitation.  Wet snow accumulations from 1 to 4 inches
will be possible above 10,000 feet late tonight through Wednesday
with local accumulations generally less than an inch possible down
to about 8,000 feet where the rain manages to change to snow.

.LONG TERM...(Wednesday night through Tuesday)
Issued at 241 PM MDT Tue Sep 26 2017

Wednesday night - Wednesday

Wednesday Night through Friday

A looming upper level low pressure system continues
to spin over Utah and will slowly propagate northwesterly with time.
The upper low will continue to eject shortwave troughs over the
region, enhancing rain chances across southeastern Colorado. Low
level clouds will remain over the plains as surface easterly and
southeasterly winds advect moisture with Gulf of Mexico moisture up
our topography. During this time period, expect below average
temperatures due to the lack of incoming solar radiation.

Saturday and Sunday

The upper-level low that has been stagnant to the west of our region
will be forced northerly as the next low pressure system enters the
contiguous United States. That low pressure system will propagate
over the Montana, Alberta, and Saskatchewan border. The upper level
pattern over southeastern and south central Colorado will transition
to the west and southwest and the surface flow will transition to a
more southerly component. The overall flow regime is combatant of
precipitation and widespread cloud cover. Sunday afternoon, a dry
cold front is expected to develop over the region, which will bring
gusty northerlies for a short period of time over the far eastern
plains. Expect near seasonal temperatures with scattered cloud cover
for the weekend.

Monday through Wednesday

After the dry cold front passage on Sunday evening, temperatures
will drop below average for this time of year, as a slightly cooler
air mass is parked over us. Starting Monday, though, a ridge of high
pressure will build over the south central United States plains,
which will cause upper level southwesterly flow, which is a dry
pattern for SE and SC Colorado. If this pattern verifies, expect a
lack of precipitation and season temperatures for this time of year
Tuesday and Wednesday.


.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 241 PM MDT Tue Sep 26 2017

Tonight and Wednesday, upper low pressure over Arizona will send a
strong surge of moisture northward into southern Colorado. It
will spread into the mountain areas overnight and then across the
I-25 corridor Wednesday morning. Showers and thunderstorms will
increase and become widespread as this moisture spreads north and
eastward overnight through Wednesday morning. Snow levels will
lower from around 10,000 feet this evening down to around 8,000
feet by noon on Wednesday. Widespread IFR/LIFR conditions will
develop above the snow level as precipitation spreads northward
tonight and Wednesday.

The KCOS and KPUB terminals will continue to see MVFR to IFR
conditions through the forecast period, with LIFR conditions
possible at times, especially late tonight and Wednesday morning
as the next round of moisture spreads northward over the area.
The KALS terminal will primarily be VFR today but will likely see
MVFR/IFR/LIFR conditions develop late tonight through Wednesday
morning as precipitation develops and spreads northward over the




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