Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 251650

Area Forecast Discussion
National Weather Service Denver/Boulder CO
1050 AM MDT MON JUL 25 2016

Issued at 1050 AM MDT Mon Jul 25 2016

Precipitable water values have dropped about 0.20 inches in the
past 24 hours. Most of the short term models show convection
staying over the mountains and south of the Denver area.

A convergence line has formed from southwest Elbert county
northeastward into eastern Arapahoe and eastern Adams due to a
Denver Cyclone. This convergence may help thunderstorms form and
will nudge pops up a little here.

Over the eastern plains...expect southeast winds to keep enough
low level moisture to hold temperatures back a little. Will lower
highs a couple of degrees for today.


.SHORT TERM...(Today and tonight)
Issued at 246 AM MDT Mon Jul 25 2016

The features to watch the next 24 hours are the upper ridge building
northward a bit across the Southern Rockies, with northwest flow
over northeast Colorado. The surface high in South Dakota will sink
southward to Kansas by this afternoon. This will bring southeast
flow across northeast Colorado which would be upslope flow into the
Cheyenne Ridge. The models also suggest an upper jet along the
Colorado/ Wyoming border. With the jet and upslope flow, raised POPs
a bit along the border. The mountains will again see the highest POPs
today. There will still be good low level moisture in northeast
Colorado...but the precipitable water in the column will be
slightly dryer than yesterday as a result of the ridging aloft.

Not sure about the NAM 00z it did not initialize the
Kansas convection very well. Today it has much of northeast Colorado
in 2500 to 3000 CAPE. Think the 1000 to 1500 CAPE on the HRRR is
much more reasonable. SPC did not show any severe for today.

Previous forecast had a good handle on things...temps and winds
looked good, only change was slight chance afternoon POPs and a
slightly faster clearing tonight.

.LONG TERM...(Tuesday through Sunday)
Issued at 246 AM MDT Mon Jul 25 2016

The upper level high will still be affecting the area on Tue with
weak flow aloft.  The ECMWF and GFS still show a weak disturbance
possibly affecting the area in the aftn and evening hours so will
continue with chc pops over the mtns.  Across nern CO there will
still be decent CAPE over portions of the plains with lower values
closer to the foothills so should see at least widely sct storms. As
for highs will keep readings in the lower to mid 90s across nern CO.

On Wed the upper level high will retrograde into the Great Basin
with the flow aloft becoming more wnw.  This will force subtropical
moisture south of the area so tstm coverage over the higher terrain
will be rather isold.  Over nern CO there are some differences in
relation to the sfc ptrn as the NAM shows a wk fnt moving across the
plains while the GFS keeps it further north across sern WY into wrn
NE.  The ECMWF had shown this wk fnt moving into nern CO but has
backed off on that scenario tonight.  Overall not real confident
about how things may evolve on Wed.  If this bndry does move across
the plains then temps would be a few degrees cooler along with an
increase in low lvl moisture.  Thus this would lead to a chc of
storms.  If the bndry stays further north then highs would stay in
the 90s across the plains with tstm coverage more isold in nature.
For now will just mention low POPs and keep highs in the lower to
mid 90s.

For Thu and Fri the upper level high will remain over the Great
Basin with increasing wnw flow aloft.  The ECMWF continues to show a
decent cool fnt affecting nern CO on Thu while the GFS has the fnt
closer to the WY-NE border.  At this point would probably favor the
ECMWF solution with highs only in the 80s across the plains versus
the GFS which has readings in the mid to upper 90s across the urban
corridor.  As far as tstms coverage in the mtns will remain rather
isold both days as subtropical moisture stays well south of the
area. Across nern CO CAPEs will be rather high both days along with
favorable shear so expect there will probably be sct stg storms as
activity develops in the foothills and then moves ese across the
plains.  Temperatures on Fri should stay in the 80s across the

By Sat the upper level high will remain over the Great Basin with
wnw flow aloft remaining over the area.  Once again a rather dry
airmass will be over the mtns so tstm activity will stay rather
isold.  Over nern CO the low lvl flow will become more sely which
will allow for deeper low lvl moisture to remain over the plains
with decent CAPE.  Thus will continue to see a threat of stronger
storms. Highs on Sat may rise a few degrees with readings in the
upper 80s to lower 90s across nern CO. For Sun the upper level high
will begin to shift eastward into CO with possibly some subtropical
moisture affecting the mtns which may increase tstm coverage. Across
the plains will keep in a slight chc of storms with highs rising
into the lower to mid 90s.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1050 AM MDT Mon Jul 25 2016

Just a slight chance for a thunderstorms late this afternoon and
evening at the Denver airports with the best chance being south of
the Denver area. With chance for a thunderstorm at the Denver
airports being 20-30 percent today will not have a mention of TS
in the TAFS. Winds are expected to stay east to northeast through
00z. Outflow winds from convection will likely produce a wind
shift or two between 23z and 03z. The winds are then expected to
settle at a southerly direction around 03z.


.BOU Watches/Warnings/Advisories...


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