Area Forecast Discussion
Issued by NWS Pueblo, CO

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FXUS65 KPUB 300513
AFDPUB

Area Forecast Discussion
National Weather Service Pueblo CO
1113 PM MDT WED JUN 29 2016

.UPDATE...
Issued at 1110 PM MDT Wed Jun 29 2016

The forecast is being updated to cancel the severe thunderstorm
watch in Kiowa and Prowers counties. The strongest storms have
moved into western Kansas. Otherwise, there is some disagreement
in the models as to where the boundary will set up Thursday. NAM
is farther north, highlighting the northern portions of the CWA
while other models have the boundary well to the south with a good
chance of thunderstorms across much of southeast Colorado. Weak
upper level disturbance moves through the area in the early
afternoon and convection should fire a bit earlier. Low level
upslope flow allows for increasing low level moisture and the
potential for heavy rain with any storms.

&&

.SHORT TERM...(This evening through Thursday)
Issued at 309 PM MDT Wed Jun 29 2016

Convection developing over the mountains again this afternoon as
moisture gradually increases, with a few storms along the I-25
corridor as of 21z. Expect storms to continue over the high terrain
and interior valleys into early evening, and with a few models
suggesting at least isolated -shra/-tsra persisting past midnight,
will keep low pops in place through early Thursday morning. Over the
I-25 corridor and eastern plains, mountain convection will gradually
spread eastward toward lower elevations, with mesoscale models
suggesting some new development out toward the KS border after 22z,
though they have been way overdone with lower elevation storms so
far this afternoon. Plenty of CAPE in place over the plains with
values in the 1500-2500 j/kg range, so an isolated severe storm is
possible, even with rather weak 0-6km shear.  Earlier thinking was
some sort of MCS would roll southward through the plains late
evening and overnight, but latest hi-res models have shifted best
forcing eastward into Neb/Nrn KS, as low level jet is rather slow to
increase over the high plains.

On Thursday, old frontal boundary sags back south through the area,
reaching the NM border by late afternoon. Deepening low level
upslope behind the front and a continued influx of mid-level
moisture from the south will lead to widespread convection across
the area, with storms developing fairly early in the day as
instability increases quickly area-wide. Convection will also be
aided by weak short wave moving through the region and cooling
temps aloft. Marginal severe threat remains in place over the
plains, though again deep layer shear is only around 30 kts, which
may limit storm strength/severity. Threat for heavy rain will ramp
up through the day, especially east of I-25 as 60f plus dewpoint
advect westward behind the front. Clouds and precip will hold max
temps down somewhat, with plains staying below 90f for a change.

.LONG TERM...(Thursday night through Wednesday)
Issued at 309 PM MDT Wed Jun 29 2016

...Active weather Thursday night through Saturday...

Upper level disturbances combined with a fledgling monsoon will keep
the threat of some severe weather and flooding going through at least
the first half of the weekend.

Thursday evening...could be the most critical part of the long-term
forecast. Pattern does not look extreme, but there are enough
ingredients in place to raise some concerns for potential flooding.
At the surface, moderate easterly or upslope flow in place. Winds
aloft will be relatively weak. Flow aloft strengthens a bit through
the evening, which will help move convection to the east, but there
could be several rounds or waves of convection moving through, which
will increase the threat of heavy rain falling on saturated ground.
Instability will be sufficient for moderate to heavy rain, with CAPE
ranging from 1-2K j/kg over the Plains. A couple of short wave
disturbances will help maintain convection through Thu evening and
overnight. Precip H2O values look in the 1.5 inch range for portions
of the plains, or about double the average. Bottom line...potential
for heavy rain is there and will have to keep an eye out for
mesoscale trend through Thu night.

Friday...Still the threat of heavy rain, but severe parameters are
elevated as well. Mid-level flow strengthens ahead of approaching
short wave trough over the 4 Corners region. Severe potential looks
highest over the Palmer dvd and far SE Plains late in the afternoon
and through Fri evening. With CAPE approaching 2000 J/kg over the
Plains and bulk sheers 40-50 kts, depending on evolution of
Convection Thu nite-Fri morning could see a risk of some severe
storms this day. Temps remain a bit below average with widespread
cloud cover and areas of precip along with upslope flow over the
Plains.

By Saturday, the short wave should be passing through Ern CO in the
morning or early afternoon. If the timing is a bit slower, could see
a repeat threat of heavy rain and/or svr wx Sat afternoon, but if
the system moves through quickly we could see a faster cut-off in
the heavy rain and svr threats. Either way, still looks like temps
will remain below average, generally in the 80s for the lowe
elevations and 60s-70s for the high country.

From Sunday and beyond, some poor consistency in the models. Earlier
runs of the GFS had a return to hot and less moist conditions with
the upper high building strongly over NM and the Desert SW. Latest
GFS is starting to trend closer to the EC...which maintains the
current weak monsoonal patter over the SW and Central Rockies. With
the uncertainties, will keep the forecast closest to the Ensemble
blends. Rose

&&

.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1037 PM MDT Wed Jun 29 2016

Thunderstorms will be more widespread across southeast and south
central Colorado aft 30/18z. Thunderstorms may impact KCOS, KALS,
and KPUB into the early evening. A frontal boundary will be the
focus for convective development along with a weak upper level
short wave moving across the state in the afternoon. Low level
upslope flow will allow for increasing low level moisture. Have
included VCTS at all TAF sites.


&&

.PUB Watches/Warnings/Advisories...
NONE.
&&

$$

UPDATE...STARK
SHORT TERM...PETERSEN
LONG TERM...ROSE
AVIATION...STARK



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