Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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704
FXUS65 KBOU 250908
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
308 AM MDT Fri May 25 2018

.SHORT TERM...(Today and tonight)
Issued at 310 AM MDT Fri May 25 2018

Ridge of high pressure aloft will be over Colorado today with a
dry and warming airmass. 700mb temperatures climb to close to
+14c which will result in another 2-4 degrees of warming from
yesterday. This will put high temperatures today close or around
90 degrees across lower elevations. Record high for Denver is 91
so likely be a degree or so shy of the record. Do not expect any
thunderstorms today but a bit of moisture around 500mb and dry
adiabatic lapse rates may result in some clouds at that level
with a bit of virga at best. Skies will become mainly clear
tonight with the ridge remaining over Eastern Colorado.

.LONG TERM...(Saturday through Thursday)
Issued at 310 AM MDT Fri May 25 2018

For the weekend, warm temperatures persist with highs reaching into
the low to mid 90s on the plains and 70s in the high country. This
will be the warmest of the year to date so precautions are urged for
heat safety and to make sure to always `Look before you Lock`.
Conditions look to be too stable and dry for convection Saturday,
however, with the pressure gradient over the plains increasing
due to a deepening surface lee trough, gusty winds on the plains
are expected. At this time speeds look to be sustained at 12 to 18
mph with some gusting from 25 to 30 mph over the eastern plains
and to a slightly lesser extent southern foothills and Park county
by the afternoon hours. This will increase fire weather concerns
over the Park County area for Saturday; more in the Fire Weather
Discussion below. Late Saturday into Sunday the upper closed low
will progress eastward moving into the Great Basin region. This
will increase SW flow aloft as well as bring an embedded shortwave
to the region. The surface low over the eastern plains will push
south helping to pull in more moisture-rich SE flow onto the far
eastern plains by Sunday afternoon. This combined with the
shortwave could be enough for some isolated storms over the far
eastern plains bordering KS. Parameters are not impressive with
cloud cover possibly holding off convective temps until much later
in the day and model deep shear is weak. Will keep pops low at
this time as confidence remains low.

Monday could see more of a stable, stratiform set-up for precipitation
as cooler air pushes out of the NW. The cooler air could run into
some warmer and drier southerly winds that could help to spark an
isolated storm or two over the eastern plains, however ML CAPE
values are not impressive as well as weak deep shear so confidence
is low on this. Temperatures on Monday will drop slightly with
highs expected to be in the low 80s. Tuesday will see isolated
showers and thunderstorms with the base of the upper trough
pushing through the state as it continues to move east.

By mid week, zonal flow and increased ridging along with subsidence
returns helping to dry out conditions and push temperatures back
into the mid to upper 80s.


&&

.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 310 AM MDT Fri May 25 2018

VFR with mainly clear skies today. A bit of moisture will develop
around 500mb late in the day for some possible virga but no
thunderstorms expected. Surface winds expected to maintain normal
diurnal patterns through tonight.

&&

.FIRE WEATHER...
Issued at 149 AM MDT Fri May 25 2018

RH levels will drop and temperatures will increase Saturday under
increased ridging and subsidence. RH levels are expected to drop
to the single digits by the afternoon hours with highs reaching
into the 90s on the plains and 70s in the high country, Park
county and foothills. Fuels are green over much of the region,
with the exception of zone 214 where fire weather conditions
could become critical by Saturday afternoon. There is currently a
Fire Weather Watch for Park County through Saturday evening, but
we held off from upgrading due to borderline winds. Models have
sfc winds 15-18 kts with 700 mb winds in the 25 kt range. With
decent lapse rates, these winds could make it to the surface by
afternoon mixing, but confidence is low this will meet RFW
criteria on timing. Either way, caution is advised for this area
as well as zones 216 and 249 where fuels could support rapid fire
growth and RH values will be low.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Saturday morning through Saturday
evening for COZ214.

&&

$$

SHORT TERM...Entrekin
LONG TERM...Bowen
AVIATION...Entrekin
FIRE WEATHER...Bowen



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