000
FXUS65 KBOU 101139
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
539 AM MDT Wed Apr 10 2024

.KEY MESSAGES...

- After a brief pause in warming Wednesday, upward temperature
  trend returns in earnest Thursday into the weekend.

- Friday through Sunday will see well above normal temperatures,
  and could bring periods of fire weather concerns given
  warm/dry/breezy conditions.

- Increased potential for unsettled weather early/mid next week.

&&

.SHORT TERM /Through tonight/...
Issued at 345 AM MDT Wed Apr 10 2024

Water vapor imagery shows a shortwave trough over western Montana
with a jet stream extending from the Pacific Northwest toward
northern Colorado. Our forecast area is under the left exit region
of this jet and QG fields show weak upward motion. Current radar
indicates there are light showers around. The radar returns over
the plains are mostly virga but a few drops may be hitting the
ground from time to time. The radar returns in the mountains
indicate there are decent snow showers ongoing over the
Continental Divide. These snow showers should persist throughout a
good portion of the day so PoPs were increased in the mountains.
Some of the higher slopes could receive up to 2 inches of snow and
minimal impacts are expected from this.

Daytime heating across the plains will create steep low level
lapse rates and some instability by the early afternoon. High
resolution model data is in decent agreement that showers and a
couple thunderstorms will form across the plains with a focus on
Weld County. The coverage of measurable rainfall will be around
30-40 percent so PoPs were increased to these levels. It will
generally be a breezy day across the plains with gusts up to 25-30
mph out of the north. These thunderstorms could create wind gusts
in the 35-40 mph range if one were to go directly overhead.
Otherwise, highs will be a few degrees below normal and will top
out in the upper 50s across the plains.

Tonight, instability will quickly weaken and clouds will clear.
Low temperatures will be around normal values.

&&

.LONG TERM /Thursday through Tuesday/...
Issued at 345 AM MDT Wed Apr 10 2024

Northeast Colorado will begin to be influenced by the eastern
flank of an amplifying ridge Thursday, with modest warming at the
700mb level and general subsidence helping to boost temperatures
area-wide between 5 to locally up to 10 degrees relative to
Wednesday`s values. Abundant sun and light winds can be expected.

The thermal ridge will continue to deepen Friday, generally
remaining over the region through the weekend and guaranteeing
well-above-normal temperatures as well as very dry conditions for
the lower elevations. Guidance is flip-flopping a fair amount as
far as which of these days would be the warmest, and ultimately
the answer may depend on the extent of cloud cover, but highs in
the mid to upper 70`s appear a sure bet for the urban corridor,
with a higher potential of some low 80`s for the rural plains.
Other than a slight chance (20-30%) of a few stray showers Friday
afternoon in the high country (owing to elevated moisture aloft
and marginal instability), the only real forecast concern for this
period would be the potential for some periods of critical fire
weather conditions in the plains, but winds could be a limiting
factor on some of those days - see Fire Weather Discussion below
for more details on that.

Ensemble guidance remains in quite good agreement in terms of the
development of an upper-level trough over the Intermountain West
to finish off the weekend, with reasonable consensus in timing and
location of this feature as it lifts into eastern Colorado
Monday. WPC clusters indicate the greatest variance (~50%) lies by
far with the system amplitude.

In any case, the current ensemble mean solutions generally keep
the bulk of the moisture to our north over Wyoming and Nebraska,
but with the southern fringe clipping our forecast area.
Considering healthy cooling aloft which could provide for some
instability, and our region being progged to be under the jet`s
favorable left exit region, precipitation potential will ramp up
for all areas. Some solutions point to fairly robust westerly flow
at the 700-500mb level, which would translate into favorable
orographics for our mountains, especially the northern ones
closest to the moisture maxima. Overall, this system should be
quite warm, so winter weather concerns are largely limited to the
mountains whilst rain will be favored for the lower elevations.
Depending on the exact timing of the associated surface front,
there may be some lingering fire weather concerns for parts of the
plains given strengthening winds and the possibility that low
humidity may linger into the afternoon hours.

The synoptic pattern supports additional troughing across the
western US through the middle of the week, so potential for cooler
conditions and continued unsettled weather will remain in the
books, with details to be ironed out as we get closer.

&&

.AVIATION /12Z TAFS through 12Z Thursday/...
Issued at 528 AM MDT Wed Apr 10 2024

VFR conditions expected throughout the TAF period. Light and
variable winds will continue until winds increase out of the
north later this morning. A cold front will move through in the
afternoon. Gusts could briefly reach 30 knots directly behind the
cold front. Winds will then weaken substantially after sunset but
will not likely return to drainage until well after midnight.

A passing jet streak will provide weak QG ascent for clouds and
showers to form along with a stray thunderstorm or two. The most
likely time for these showers to move across the terminals would
be during the mid afternoon. These showers or storms may produce
gusts up to 30-35 knots if one were to directly move over a
terminal. Ceilings will likely be in the 7-10 kft range tonight
through much of the day today.

&&

.FIRE WEATHER...
Issued at 142 AM MDT Wed Apr 10 2024

A steady and pronounced warming and drying trend will take hold
Thursday and Friday, with very warm and dry conditions expected
from Friday through Sunday. Relative humidity values in the upper
single digits to mid teens will likely be widespread for the lower
elevations during this period.

Ultimately, the extent of fire weather concerns for the plains
will be driven by the winds. Synoptic forcing will be limited
during this period, with winds being largely driven by diurnal
mixing. Currently, mixing appears most efficient Saturday, and
thus the forecasts reflects the breeziest conditions on this day.
Even they, they should not be particularly strong, but may be
sufficient to meet Red Flag criteria. Locally critical conditions
can`t be ruled out for parts of the plains Friday or Sunday
either, but should be patchier in nature.

Monday is tricky as far the fire weather threat goes, as there`s
uncertainty in the timing/extent of a cold front that would bring
increased moisture and precipitation chances. The farther
southeast in our forecast area, the greater the likelihood of
renewed fire weather concerns Monday.

&&

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

&&

$$

SHORT TERM...Danielson
LONG TERM...Rodriguez
AVIATION...Danielson
FIRE WEATHER...Rodriguez