Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

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FXUS65 KBOU 130905

Area Forecast Discussion
National Weather Service Denver/Boulder CO
305 AM MDT Tue Mar 13 2018

.SHORT TERM...(Today and tonight)
Issued at 300 AM MDT Tue Mar 13 2018

Drier, stable air will spread down from Wyoming this morning in
the wake of a weak mid-level shortwave which was now passing over
east central CO/west central KS. As this feature moves away,
should see a gradual reduction in the scattered to broken mid-
level cloud cover through the morning. However, later today the
combination of solar heating and a south-southeast low-level flow
could produce low top convective clouds over the Rampart, Mosquito
and Ten Mile Ranges, and from possibly a brief snow shower to two.
Nothing of consequence. Otherwise, northwest flow aloft will
remain in place until passage of a sharp upper-level ridge on
Wednesday. Temperatures next 24 hours are expected to run near to
slightly above average with highs on the plains in the low to mid
50s, and from the mid 30s to near 50 degrees across the high

.LONG TERM...(Wednesday through Monday)
Issued at 300 AM MDT Tue Mar 13 2018

Main concerns in the long term revolve around an ejecting storm
system which will move across Northern Colorado Late Thursday and
another storm system on  Sunday.

Until then, Wednesday looks to be the warmest and driest day of
the week as the ridge of high pressure will move across Colorado
and 700mb temperatures climb to around +4c over the Front Range.
This will put temperatures close to 70 degrees over the plains.
Changes expected Wednesday night and Thursday as moisture
increases across the mountains ahead of approaching storm system.
Models are in better agreement tonight with the NAM the quickest
in ejecting the low into the central plains, while the GFS/European
solutions are slower and the Euro is furthest south. Appears the
mountain areas and the far northeast plains will benefit the most
from this storm with more moisture and stronger upward forcing. QG
Numbers showing substantial lift Thu afternoon/evening over the
far plains and this is where the highest pops/qpf will be.

Forecast soundings showing about 400-600j/kg of sfc based CAPE
Thursday afternoon as surface dewpoints climb into the 30s so
could even have a few thunderstorms. Interestingly, PW values
ranging from .55-.65 of an inch over the plains and around .45"
over the Front Range. This is near the climatological maxes for PW
for this time of year and bears watching considering the model
QPF of the GFS/NAM are quite high. Will certainly undercut the
high numbers for now but will watch this closely as low level
moisture is being drawn up from the central plains. Behind the
low, mountain top flow will increase from the west and northwest
Thursday night and early Friday with wind gusts in the 40-60 mph
range possible. Given the strong orographic component and cold
advection, certain some modest snow accumulations are possible
with advisories the most likely choice but way too soon.

Improving conditions on Saturday under weak ridging aloft over
Colorado. Another Pacific system will then be poised to move
across the state on late Saturday night and Sunday. The track of
this system looks to eject the low further north into Wyoming so
again best chance for precip will be over mountains and far
northern Colorado.


.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 300 AM MDT Tue Mar 13 2018

VFR conditions will prevail through tonight. Scattered to broken
cloud cover with bases in the 6000 to 8000 feet AGL range early
this morning should gradually lift and move east-southeast away
from the metro area by mid-morning. Precipitation is not likely
from these clouds. Light southerly winds on the south side of the
metro area and north-northwest winds under 10 kts on the north
side, will become predominately south-southeast in direction at
6-12kts by late morning. During the afternoon, winds are expected
to turn east-southeasterly at similar speeds. With nightfall,
plan on a light drainage (south-southwest) wind pattern under a
mostly clear sky.




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