Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 260926
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
326 AM MDT Fri May 26 2017

.SHORT TERM...(Today and tonight)
Issued at 315 AM MDT Fri May 26 2017

An upper level trough will extend fm the nrn Rockies into the nrn
Great Basin and will move slowly eastward thru tonight.  In the
lower levels a Denver Cyclone will dvlp by early aftn and the
convergence zone associated with this feature will be a focus for
tstm development. Hi res data has been pretty consistent so far in
showing this bndry mainly to the south and east of Denver with
convection developing by 19z and then moving eastward towards the
Akron and Limon areas by 00Z. Soundings show favorable shear
profile so would expect a svr tstms with large hail and damaging
winds. An isold tornado or two will be possible where helicity is
enhanced along the convergence zone. At this time main threat of
svr appears to be mainly se of a line fm Denver to Akron. Further
north svr threat may be more isold. Across the higher terrain some
drier air will spread across today so showers and storms this
aftn may end up being more widely sct. As for highs this aftn
readings will range fm 65 to 70 north of a Denver to Akron line
with lower to mid 70s elsewhere across the plains.

For tonight showers and storms will continue across the plains thru
the early evening hours.  By mid to late evening a cdfnt will affect
the plains.  The hi res data shows pcpn ending by midnight while
ECMWF and GFS continue to show additional pcpn across the plains
well after midnight behind the fnt.  Across the higher terrain cross-
sections show moisture will increase after midnight with some mid
lvl ascent developing as main upper level trough begins to move into
wrn CO. Thus may see an increase in shower activity especially north
of I-70 after midnight.

.LONG TERM...(Saturday through Thursday)
Issued at 315 AM MDT Fri May 26 2017

Saturday and Saturday night, the upper trough axis in the morning
will stretch from northeast WY into southwesterly UT with a
southwesterly flow over the cwa. Weak mid level qg ascent will be
over the forecast area in the morning, then weak qg descent is
progged to occur in the afternoon and continue into the evening.
The showers will be more widespread through early afternoon then
the focus will shift to along the Palmer Divide by late Saturday
aftn and evening. Low level stability will increase as surface
high pressure increases across the cwa. Showers will be more of
an issue vs thunderstorms with increasing stability developing.
Sunday and Sunday night, it will be drier with a surface high
over the Central Plains and weak mid level qg descent over the
area. Showers and thunderstorms will still be possible but will be
over the higher terrain with the greatest stability over the
northeast plains. The flow aloft will be relatively weak early
next week, transitioning from northwest to westerly. It will be
warmer with enough instability around in the afternoon and
evening for a chance of thunderstorms, again primarily over the
higher terrain with a lesser chance across the plains. The next
Pacific system will start to move into the Great Basin region by
Thursday, which may help to increase the chance of tstms over the
mountains late Thursday into Friday.

&&

.AVIATION...(For the 12Z TAFS through 12Z Saturday morning)
Issued at 315 AM MDT Fri May 26 2017

Another complicated fcst today.  Denver cyclone is fcst to dvlp by
midday sw of DIA with convergence zone staying south and east. If
that`s the case then the threat of stronger storms would stay
mainly south and east as well. However if it ends up being
further north then the threat of stronger storms would increase.
As for winds if the cyclone does stay to the sw then winds would
gradually become more ely by early aftn. However outflow
boundaries fm convection will likely cause chaotic winds
directions by mid to late aftn. By early evening tstm threat
should diminish with winds mainly sely. Around midnight a cdnft
will move across and there will likely be stratus development
thereafter lasting thru Sat morning.

&&

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

$$

SHORT TERM...RPK
LONG TERM...Cooper
AVIATION...RPK


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