Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 242131

Area Forecast Discussion
National Weather Service Pueblo CO
331 PM MDT Wed May 24 2017

.SHORT TERM...(This evening through Thursday)
Issued at 304 PM MDT Wed May 24 2017

Upper ridge migrating across the Rockies today, bringing the warmest
temps in nearly 2 weeks to much of the region. Ridge moves into the
central plains overnight, as wly flow gradually increases across
Colorado in response to upper trough moving across srn Canada.
Increasing winds plus lee surface trough over the plains should keep
mins mild overnight, especially in the lee of the eastern mountains.
On Thursday, fairly deep swly flow develops across srn CO as 90 kt
upper jet lifts eastward through the srn Rockies. Farther north,
cold front will drop into nrn CO, hanging up near the Palmer Divide
by late afternoon. Expect tsra chances Thu afternoon to be rather
limited, as sw flow will keep dry air in place across most of the
region, with best chance over the central mtns where dynamic lift
will be strongest. Over the plains, position of the cold front will
determine tsra chances, as fairly deep instability will lurk over
the nrn fringe of the area, especially along the Palmer Divide and
across Kiowa county. Certainly enough shear for a severe storm or
two if front can dip south, with latest SWODY1 marginal risk grazing
portions of El Paso/Kiowa counties looking reasonable. Expect
another warm day most locations with deep mixing and dry air, and
maxes will push deep into the 80s across much of the eastern

.LONG TERM...(Thursday night through Wednesday)
Issued at 304 PM MDT Wed May 24 2017

Not much change to the forecast thinking through the extended
period. Active weather is expected to persist across Southern
Colorado, and models out beyond seven days indicate the active
weather will persist into late next week.

Thursday night and Friday...strong to severe storms are expected
to be ongoing across the Palmer Divide into northeast Colorado
Thursday evening. Coverage will depend highly on how far south a
cold front will drop south, as the main upper disturbance will
remain well to our north. Current thinking is areas along the
Palmer Divide, southeast into Kiowa County may see one or two
strong to severe storms during the evening hours. Large hail and
strong winds will be the primary threats. Further south, expect
dry conditions to prevail through the overnight hours, into Friday
morning. If the front does push further south than current model
projections indicate, the risk for thunderstorms will also shift
south. This will need to be monitored closely.

A secondary upper disturbance is forecast to track across northern
Colorado on Friday. Lee cyclogenesis will set up a surface low
near Pueblo by Friday afternoon. Models develop another low level
boundary, running from the Palmer Divide, southeast to near
Springfield. Scattered thunderstorms are expected over the Palmer
Divide along the boundary, nearer to the upper disturbance.
Further southeast, high-res models do develop isolated
thunderstorms from Lamar down to Springfield. CAPE values
approaching 2000 j/kg and modest shear around 40 kts should allow
for updraft rotation and storms to become severe. Large hail and
damaging winds will be the primary threats, however, a quick spin
up landspout may be possible along the boundary. Again, how far
south and west convection develops will depend highly on where the
surface low and boundaries set up.

Saturday and Sunday...a much stronger upper disturbance is
forecast to move across Colorado on Saturday. A cold front will
drop south by the early morning hours with moist easterly upslope
flow developing across the Plains. Expect widespread showers and
thunderstorms across the region by Saturday afternoon. Models
indicate areas along the Eastern Mountains, east into the I-25
corridor may see locally heavy rainfall. This may lead to flash
flooding on area burn scars and will need to be monitored closely.
The severe threat looks limited Saturday due to cooler
temperatures and modest instability.

Continued moist upslope flow in the low levels will keep
widespreadshowers and thunderstorms going through the day
Sunday, especially over the mountain areas. The flash flood risk
will remain elevated due to locally heavy rainfall. Temperatures
will remain cool with lower 70s for highs.

Monday through Wednesday...the upper level pattern looks to become
more monsoon-like through next week. High pressure is forecast to
develop and sit over the Great Basin, while a weak upper low is
forecast to move off northern Baja. Broad northwest flow aloft is
expected through midweek due to a storm system over the Great
Lakes. Instability and moisture across the region will lead to
diurnally driven showers and thunderstorms over the mountains,
spreading east into the Plains each evening for Monday and
Tuesday. By Wednesday, disturbances wrapping around the low of
Baja will begin to move north out of the Desert Southwest and
across Colorado leading to more widespread shower and thunderstorm
activity. Flash flooding will remain possible on area burn scars
due to locally heavy rainfall. Another thing to consider as we
move into next week, will be increased rainfall over mountain
areas that still have high snow packs, which could lead to high
flows on area rivers and streams by mid week.  Mozley


.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 304 PM MDT Wed May 24 2017

VFR conditions expected at all terminals the next 24 hrs. Central
mountains north of KMYP will see isolated -tsra return after 18z Thu
as moisture increases, with a low risk of convection over the Palmer
Divide north of KCOS after 21z.




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