Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Pueblo Colorado
455 am MDT Monday may 4 2015

Short term...(today and tonight)
issued at 448 am MDT Monday may 4 2015

Currently...the upper low pressure system was moving onshore across
Southern California early this morning...drawing a plume of moisture up
across the desert SW and into the rocky Montana region. A good amount of
lightning was being detected across Arizona this morning...as well as some
strikes over the transpecos region. As for Colorado...spotty light
stratiform rain for the forecast area which was starting to fill
in...and temperatures holding steady in the middle 40s to middle 50s.

Today and tonight...the upper low will move across Arizona and near the 4
corners over the next 24 hours...spreading abundant moisture up across
the County Warning Area through tonight. Shower activity occurring early this
morning seems to be grouping along the Palmer dvd...and hi res
models indicate that the rest of the area should see at the most
isolated activity this morning through about midday.
Then...convection starts to increase once again...and the potential
for moderate to at times heavy bands of rain will be in place across
the eastern plains through tonight. Total quantitative precipitation forecast forecast ranges from
half an inch to near an inch of water for the east mts and plains from
this afternoon through 12z Tuesday...while the slv and Continental Divide may see .2 to
3 inches of rain in the same time frame. There is also the
possibility of a few stronger storms over the far southeast corner this
afternoon and evening...and Storm Prediction Center has included roughly from lhx and eastward in
the marginal area. Thunderstorm potential will continue into the
night...so kept T in the weather grids overnight. As for temperatures...look for
maximum temperatures in the 60s for most areas today...with the far eastern
plains possibly warming into the lower 70s. Moore

Long term...(tuesday through sunday)
issued at 448 am MDT Monday may 4 2015

..forecast concerns will revolve around heavy rain potential and a
marginal severe weather threat for Tuesday...with burn scars most at
risk for flash flooding...

Upper trough over the Desert Southwest lifts to the northeast across
Colorado on Tuesday. Widespread showers and thunderstorms will be ongoing
early Tuesday morning as the upper trough lifts towards the 4 corners
region and lead impulse enters southern Colorado during the early
morning hours. Showers and embedded thunderstorms will be most
numerous across the far southeast plains early Wednesday
morning...with a second area of focus across northern portions of
the southeast plains...and Pikes Peak region to the north of a
northward progressing warm front. In fact...700 mb flow Tuesday morning
is southeasterly...which would provide an added upslope component
for the Pikes Peak region...and parts of Fremont County and
western Pueblo County Tuesday morning. There could be some embedded
moderate rainfall...which will keep all eyes closely monitoring
the burn scars during the early morning hours. Quantitative precipitation forecast totals on the
GFS look overdone though...and likely the result of convective
feedback...but precipitable waters will be running around .75 to
around an inch across the southeast plains...and model soundings
show tall thin cape profiles with low LCLs and good
saturation...certainly fitting the definition of a potential heavy
rain profile.

As the system lifts northward during the day...a surface
low develops across southeast Colorado...and a dry line takes shape
across southern portions of the southeast plains. It is along this
feature that strong to severe convection may have the best chance
of developing during the afternoon and evening as destabilization
takes place. High res nmm and arw runs seem to depict this
potential. Nam12 shows cape values of 1500+ j/kg across portions
of the far southeast plains. Deep southerly flow results in 0-6km
shears within the instability axis of around 20 kts...which is on
the low side...though if low level winds back a bit more from the
east...then this might increase deep layer shears sufficiently.
Main threat for now looks like hail over 1 inch in diameter and
wind gusts over 60 miles per hour and really can't argue with the current day
2 convective outlook depicting a swath of marginal criteria.
Across northern portions of the southeast plains...including the
Pikes Peak region...there is less certainty as to how much
destabilization will occur in the afternoon. NAM keeps rain going
through the early part of the day across Teller and El Paso
counties which may limit convective available potential energy and keep precipitation more
stratiform in nature. However...as stronger forcing moves in
during the afternoon...heavy rain threat increases as lapse rates
aloft steepen some...and as mentioned earlier...tall thin profile
to the cape in model sounding suggests potential for heavy
rainfall with burn scars...particularly Waldo...the most
vulnerable. Not to be left out...the West Fork complex will also
have to be monitored closely Tuesday afternoon as snow levels will
remain quite high (around 11- 11.5kft) through the event. Showers
and thunderstorms will eventually lift off to the north during the
evening hours...and threat for flash flooding should diminish for
the eastern mountain burn scars after 03z if not a little sooner. Even though
snow levels stay fairly high...higher peaks could pick up around
6-10 inches of snow through the event. Given this will be mainly
above pass levels...will hold off on issuing any advisories.

Upper low pulls off to the northeast Tuesday night/early
Wednesday...with residual showers continuing across the mountain
areas. Surface low across east central Colorado on Wednesday should allow
westerly downslope flow to boost temperatures to back above normal
for the southeast plains Wednesday afternoon. Dew points decrease
some...though with more sun...we should see another round of
instability showers and thunderstorms over and near the mountains
during the afternoon.

Weather pattern remains active for the longer term...with yet
another upper trough/closed low dropping southward through California on
Thursday...then lifting to the east and northeast across the Great
Basin Friday night and across Colorado on Saturday. European model (ecmwf) and GFS are fairly
similar with the overall pattern...though ec is a tad farther south
with the track of the upper low across Colorado on Sat. Thus will keep
isolated to scattered showers and thunderstorms in the
forecast...with the best chance for showers and thunderstorms across
the southeast mts/adjacent plains on Friday behind a front. European model (ecmwf)
keeps this front a tad farther north...with focus more across ec and
NE Colorado on Friday. This far out...details are bound to change...but
with the trend towards a slightly farther south track...will keep
scattered probability of precipitation across the Continental Divide and Pikes Peak region Friday
afternoon and evening...then a drying and warming trend returns for
late next weekend as the system lifts off to the northeast. -Kt

&&

Aviation...(for the 12z tafs through 12z Tuesday morning)
issued at 448 am MDT Monday may 4 2015

A wet regime will be in place over the next 24 hours as the upper low
pressure system approached the 4 corners. There should be a brief
lull this morning until around 18z...with VFR conditions in place.
The east mts and plains are expected to see the heaviest bands of rain
and storm activity...so after 18z kcos and kpub will likely vary
between MVFR and IFR conditions. Kals and the slv will see less
intense showers...so intermittent VFR to MVFR conditions there.

&&

Pub watches/warnings/advisories...
none.
&&

$$

Short term...Moore
long term...knots
aviation...Moore

National Weather Service Glossary of Abbreviations