Area Forecast Discussion
Issued by NWS Denver/Boulder, CO

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
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 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

FXUS65 KBOU 162135

Area Forecast Discussion
National Weather Service Denver/Boulder CO
335 PM MDT Fri Mar 16 2018

.SHORT TERM...(This evening through Saturday)
Issued at 335 PM MDT Fri Mar 16 2018

The pesky precipitation on the back side of the upper low has
finally ended over northeast Colorado. There is a pretty uniform
north-northwesterly wind fields over most of the plains. There are
many boundaries around on the area radars with a couple of weak
convective cells over Weld County right now. There are west-
southwesterlies over the greater Denver area. Models show an upper
ridge push across Colorado tonight. On Saturday...southwesterly
flow aloft is expected as the next upper trough develops west and
northwest of us. There is downward synoptic scale energy for the
CWA tonight, then weak upward QG vertical velocity on Saturday.
For moisture, it is pretty dry over the plains tonight and
Saturday. There is a bit of moisture to increase over the
mountains on Saturday. Will go with a tad of pops over the high
mountains late Saturday afternoon with the approaching moisture
and system. For temperatures, Saturday`s highs will be about 5 C
warmer than today`s highs.

.LONG TERM...(Saturday night through Friday)
Issued at 335 PM MDT Fri Mar 16 2018

Flow aloft over Colorado will be out of the southwest, ahead of an
upper trough moving into the Great Basin. Moisture will be on the
increase over the mountains, but the plains will remain dry with
southerly winds keeping temperatures mild.

By Sunday, the upper trough will be moving over northern Arizona
and developing into a closed upper low near the Four Corners
region. Each of the medium range models show good agreement with
the motion and evolution of this feature. At the same time a
surface low is forecast to develop over southeastern Colorado
which will deepen through Sunday evening. Quasi-geostrophic
diagnosis shows this system will contain strong dynamic forcing
for ascent through Sunday and into Sunday night. The airmass over
eastern Colorado should moisten through the day due to the rising

Model soundings show a modest instability over the plains Sunday
afternoon as cool temperatures aloft approach with the upper low.
Enough instability should be present to mention the chance of
thunderstorms over the mountains and out onto the plains Sunday
afternoon. The convective nature of the showers Sunday aftenroon
and evening may cause locally heavy snow showers to develop in
the mountains. An advisory will probably be necessary when the
time comes.

Rain showers on the plains late Sunday afternoon should change
over to snow Sunday night as the airmass cools down with the
maturing storm system. The upper low will be progressing eastward
through Sunday night which will limit the amount of time that deep
upslope northeasterlies are in place along the foothills and I-25
corridor. These areas could see 6 to 9 hours of precipitation with
accumulations being limited by when the changeover to snow occurs
on the frontside and by the ending of the precipitation during the
pre-dawn hours on Monday. During that time, one to 4 inches of
snow could fall on the plains. There will be some potential for
heavy snow Sunday night south of Denver extending towards the
Limon area based on the current track of the upper level low.

The storm will be clearing out of the state Sunday morning with a
return of drier weather on the plains. Mountain areas will see a
continuation of scattered snow showers as northwesterly flow
develops over the state. The remainder of the week will see a
gradual warming trend as models show upper ridging coming to
dominate the weather picture over the Rocky Mountain west.


.AVIATION...(For the 18Z TAFS through 18Z Saturday afternoon)
Issued at 335 PM MDT Fri Mar 16 2018

The winds are stronger than expected at DIA and due westerly in
direction. Earlier models were a bit off on that. Normal drainage
winds are still expected at DIA by 05Z. Where will be no ceiling




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