Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 212114

Area Forecast Discussion
National Weather Service Denver/Boulder CO
314 PM MDT Mon May 21 2018

.SHORT TERM...(This evening through Tuesday)
Issued at 314 PM MDT Mon May 21 2018

Isolated to scattered afternoon thunderstorm activity over the
mountains is expected to come to an end through the evening with
the loss of daytime heating. Clearing skies will then occur
overnight. Tomorrow should be a repeat of today as the moist
southwest flow aloft continues. An embedded short wave should be
enough to produce another round of thunderstorms through the
afternoon. Once again, most of the activity should be over the
higher terrain. A surface low pressure area over eastern Colorado
tomorrow will produce a bit of a Denver Cyclone over the urban
corridor that will help to keep moisture pooled against the
foothills. Forecast CAPE values further east on the plains
indicate only weak instability, so only isolated probability of
precipitation forecasts will result. With only marginal
instability, strong to severe thunderstorms are not expected.

.LONG TERM...(Tuesday night through Monday)
Issued at 314 PM MDT Mon May 21 2018

...Summer-like weather expected much of this upcoming week...

Weak short wave and associated showers and thunderstorms are
expected to push off to the northeast Tuesday evening. Drier air
works in overnight with gradual clearing expected. Very warm and
drier southwest flow Wednesday will bring warmer temperatures and
probably less thunderstorm coverage by then. The northeastern
plains could still see a couple stronger storms in the afternoon
with better low level moisture holding in place with southeast
winds. CAPE could reach 1500-2000 J/kg, and bulk shear of 30-40
knots would be sufficient for a severe storm threat. However, the
warmer air aloft and lack of short wave will likely keep any storm
coverage limited.

On Thursday and Friday, the flow aloft will turn more westerly and
weaken with flat upper level ridging expected. As a result, we
should see a continuation of warm temperatures but less
thunderstorm coverage. High temperatures should push well into the
mid to upper 80s across the plains.

By Saturday, the upper level ridge will likely amplify over the
state as the next upper level low drops into California. Expect
another very warm and mostly dry day with such sharp upper level
ridging. Would not be surprised if Denver reaches 90F at some
point in the Thursday through Saturday period.

The next upper low is advertised by most medium range models to
open up and lift northeast across the Central Rockies late Sunday
into Monday. Confidence decreases in the timing here, so we`ll go
with a slight chance of thunderstorms and offer a few degrees of
cooling by next Monday.


.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 314 PM MDT Mon May 21 2018

Minimal aviation impacts through tonight and Tuesday as the drier
airmass will remain too stable for thunderstorms to develop on
the plains. Winds this afternoon will be driven by outflow from
decaying showers coming off of the foothills. Drainage southerly
winds are expected overnight. Tomorrow should see east to
southeast flow until shower activity in the afternoon causes
variable and gusty winds.




SHORT TERM...Dankers
LONG TERM...Barjenbruch
AVIATION...Dankers is the U.S. government's official web portal to all federal, state and local government web resources and services.