Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

Home | Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
000
FXUS65 KBOU 190203
AFDBOU

Area Forecast Discussion
National Weather Service Denver/Boulder CO
803 PM MDT Sat Mar 18 2017

.UPDATE...
Issued at 803 PM MDT Sat Mar 18 2017

It is a quiet and mild evening. Will add more cloud cover to the
forecast. Satellite showing upper level moisture increasing and
this should result in more high clouds. No other changes to the
forecast are expected.

&&

.SHORT TERM...(This evening through Sunday)
Issued at 255 PM MDT Sat Mar 18 2017

Unseasonably warm weather will continue through Sunday with upper
level ridge axis shifting eastward across the state. There is a
weak wave passing to our north Sunday morning which knocks the
ridge down slightly, increasing westerly flow aloft. This will
increase the fire danger...see Fire Weather section below.
Temperatures may cool just a degree or two in the mountains and
right near the Front Range with slight cool advection from the
passing short wave, but farther east on the plains the increased
downslope component probably means another degree or two of
warming there.

Otherwise, there will be a period of low level moisture advection
on the far eastern plains tonight, with only a low threat of
stratus there.

.LONG TERM...(Sunday night through Saturday)
Issued at 255 PM MDT Sat Mar 18 2017

12z run of the various models have come into better agreement,
particularly during the first half of the long term period.
Starting out Sunday night and Monday, models show a flat upper
ridge over the region and a warm and dry zonal flow aloft. At low
levels...models show a weak frontal surge backing into nern
Colorado during the day, ushering in higher sfc dewpts and
slightly cooler temperatures. The most noticeable change will be
felt acrs the northeast corner during the afternoon. Higher Rhs,
lower temps and lighter winds should reduce the wildfire danger at
lower elevations. By late afternoon...steepening mid-level lapse
rates with a passing weak upper air disturbance should be
sufficient to initiate a few showers over higher elevations. Very
warm temps aloft should keep any snowfall in the high country
above timberline. Could see a stray shower or two move off the
Front Range and out over the plains during the evening. Any qpf
should be minimal.

On Tuesday...resident upper ridge flattens further as it shifts east
of the state putting us under a more moist southwest flow aloft.
Weak upslope flow on the plains will prevent much warming but fcst
highs still several degs above average. By mid-afternoon...low-level
wind fields show the formation of a Denver cyclone southeast of the
metro area Low level moisture advected northwest around this sfc low
is progged to generate sfc based CAPES in the 250-350 j/kg range acrs
Ern Elbert and swrn Arapahoe counties. With enough shear could see a
few t-storms fire along this axis. Gusty winds and light rainfall
main products of these isolated cells. Also added low pops over and
along the Front Range during late afternoon and early evening hours.
Overnight...east-southeast upslope flow continues to strengthen which
further moistens the plains airmass possibly resulting in areas of
stratus and fog.

Wednesday-Friday...focus turns to the large upper trough which
models have oscillated on its position and amplitude the past few
days. Models now show the upper trough over the desert southwest
Wednesday night and a warm southwest flow over Colorado. By 18z
Thursday the GFS shows the 500 mb trough over Colorado, while the
European and Canadian models still show it back over Utah and
Arizona. By Friday morning...the GFS shows the trough with a deep
closed upper low over ern Nebraska, while the EC has a deep closed
low over sern CO/nern NM. The Canadian has an open upper level
trough over Colorado. These differences add much uncertainty to the
forecast beyond Wednesday. For now, will trend wetter and cooler
Thursday and Friday.

&&

.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 803 PM MDT Sat Mar 18 2017

VFR conditions will prevail through Sunday with high clouds
streaming across the state. Easterly winds this evening are
expected to turn southerly by 06Z. On Sunday, better mixing will
occur with westerly winds expected to develop and increase to
10-15 knots toward 18Z with a few gusts around 20 knots possible
18Z-00Z.

&&

.FIRE WEATHER...
Issued at 255 PM MDT Sat Mar 18 2017

Fire danger will increase on Sunday. Westerly winds are expected
to increase, while temperatures and humidity levels will be
similar to those observed today. Locations from the northern
Foothills through the northern border area on the plains will see
Red Flag criteria with gusts of 30-35 mph, and RH down to near
10%. Warnings remain in effect there. Farther south from Greeley
and Denver east to around Akron and Deer Trail, winds are expected
to be mostly in the 10-20 mph range, so criteria may not be met.
There is still a moderate low level gradient in place however, so
still some potential for stronger winds. Therefore, we will keep
the Fire Weather Watch in effect in those locations for now.

&&

.BOU WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from noon to 7 PM MDT Sunday for COZ215-238-242-
248-250-251.

Fire Weather Watch from Sunday afternoon through Sunday evening
for COZ239-240-243>245-249.

&&

$$

UPDATE...Meier
SHORT TERM...Barjenbruch
LONG TERM...Baker
AVIATION...Meier
FIRE WEATHER...Barjenbruch



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.