Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 280311
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
911 PM MDT Thu Apr 27 2017

.UPDATE...
Issued at 859 PM MDT Thu Apr 27 2017

Some prelim thoughts on the oncoming storm...

1.) the MCV spinning over the NE/KS/CO region I believe will have
an impact on the PUB and COS areas receiving LESS precip from
this system. This MCV (along with another 700 mb low currently in
WY, will cause an elongated and "flat" 700 mb pattern over the
region and this in turn will initially prevent the 700 mb flow
from "tightening up" over the region tomorrow night. This will
prevent a really favorable upslope pattern from developing over
the PUB and COS area. The PUB and COS area will still receive a
decent amount of snow/rain with this event, but this 700 mb
pattern will likely prevent a very heavy precip event over the
above mentioned areas.

2.) The 00 UTC NAM is slower with the system once it moves just
east of the area. If this verifies, it will keep a prolonged area
of precip over the far eastern plains. Temps with this system will
be cold enough for snow all the way out to the KS border. If the
NAM were to verify, then heavy wet snow would likely occur over
the the far eastern plains. Winds are quite strong (>50 knots) Sat
nite and into early Sun over the plains.

I do not plan to make any updates to the digital forecast as other
models still need to come in, but I wanted to pass my latest
thinking onto you. As we all know, things can change so please
stay tuned regarding this event. /Hodanish

UPDATE Issued at 559 PM MDT Thu Apr 27 2017

Update for expiration of the Winter Weather Advisory for zones 58
and 60, as well as incorporating latest radar/satellite trends
and obs data. Moore

&&

.SHORT TERM...(This evening through Friday)
Issued at 327 PM MDT Thu Apr 27 2017

Upper wave crossing Colorado this afternoon, with axis of
strongest lift emerging from the mountains and pushing across the
plains as of 21z. LAPS/mesoanalysis CAPEs running in the 500-1000
j/kg range along and east of the mountains, with some modest tsra
producing small hail across El Paso county over the past 1-2 hours.
Forecast soundings and mesoscale models continue to suggest
potential for near severe winds over the plains as storms congeal
into a rather disorganized line and push toward the KS border by
early evening. Farther west, convection over the mountains should
diminish quickly as best lift shifts east, and will allow Winter Wx
advisory to expire on schedule, as snow fades to flurries through
the evening along the Continental Divide. I-25 corridor will see
briefly gusty winds behind departing convection, before speeds
diminish this evening. Should be enough wind to keep lower elevation
min temps from falling below freezing, though a few spots along I-25
could see some patchy frost by early Fri morning.

On Fri...should see a lull in precip in the morning, before upper
level low begins to take shape across the 4 corners during the
afternoon, bringing increasing showers to much of the area by late
day as upward motion intensifies. Cold front and deepest cold air
look to stay north of the Palmer until late afternoon, with
steadier/heavier precip holding off until around 00z. Max temps will
be cooler most locations as clouds increase and temps aloft begin to
cool.

.LONG TERM...(Friday night through Thursday)
Issued at 327 PM MDT Thu Apr 27 2017

Friday night through Saturday...The upper low pressure system drops
south across the Four Corners Friday night, then tracks to the east
across New Mexico and into Texas through Saturday. Most of the
models agree with this track, though the EC hangs onto pcpn for the
e plains a bit longer Sun am. However, all the models are indicating
that qpf amounts are much lower than originally anticipated just 24
hrs ago. The best window for activity and accumulating snowfall
still looks like Fri night into Sat aftn for all of the higher
terrain, Palmer Divide, Raton Mesa and southern foothills, but model
confidence has taken a hit. Therefore, will maintain the watch as
surrounding offices have done, and hopefully model runs tonight will
paint a clearer picture. The question will be either to issue a
winter storm warning or winter weather advisory since snowfall
amounts are in doubt, not the fact whether or not it will snow.
Expect a cold Friday night and day on Saturday, with max temps
climbing to right around 40F.

Sunday and Monday...Expect brisk N-NW flow and perhaps some
lingering showers for the plains on the back side of the departing
low Sunday morning, then a more relaxed NW flow aloft for the entire
forecast area Sunday afternoon and through Monday. Due to the
favorable flow, there will be a continued threat of isolated showers
for the central mts and perhaps Pikes Peak sun night through Mon.
Cool max temps in the 40s and 50s on Sun will warm into the 50s to
near 60F for the plains on Mon.

Tuesday through Thursday...A stronger shortwave crosses the Rockies
on Tue, producing a better shot of convection for all of the
forecast area including the plains for Tue afternoon through Wed
afternoon. Dry NW flow then settles in for the state on Thu. Look
for high temps in the 50s to lower 60s both Tue and Wed, then in the
60s to near 70F for Thu. Moore

&&

.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 327 PM MDT Thu Apr 27 2017

Isolated -shra/-tsra moving across the area this afternoon, though
expect most convection to be east of all 3 terminals by 00z as wave
axis is already pushing out onto the plains as of 21z. Expect VFR
conditions at all taf sites tonight and through midday Friday,
before showers begin to increase after 21z. Bulk of precip and IFR
conditions to develop after 03z Fri evening, with widespread
IFR/LIFR in rain and snow overnight Fri and through the day Sat.
Over the mountains, still some patchy IFR cigs along the Continental
Divide into the evening, with at least some partial clearing
overnight and through the first half of the day on Fri. Precip will
increase Fri afternoon, with most higher terrain obscured by
clouds/precip by 00z.


&&

.PUB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Watch from Friday evening through late Saturday
night for COZ058>061-063-066-068-072>076-078>082-084-087-088-094.

&&

$$

UPDATE...HODANISH
SHORT TERM...PETERSEN
LONG TERM...MOORE
AVIATION...PETERSEN



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