Area forecast discussion
National Weather Service Pueblo Colorado
1125 PM MDT Tuesday Jun 18 2013
Update...
issued at 903 PM MDT Tuesday Jun 18 2013
Updated for expirations of Severe Thunderstorm Watch 325 and to
reflect current and forecast short term precipitation trends.
Update issued at 733 PM MDT Tuesday Jun 18 2013
Updated to remove a portion of Severe Thunderstorm Watch 325 and
to reflect current precipitation trends.
&&
Short term...(this evening through wednesday)
issued at 253 PM MDT Tuesday Jun 18 2013
..high impact weather to affect the area through the short term...
Severe weather through this evening...shifting to fire weather for
Wednesday...
Severe thunderstorm threat still looks high through this evening.
Thunderstorms are already firing along the southeast mountains
(southern sangres) as southern jet stream approaches The Four
Corners region. Thunderstorms also firing across northern/cen Colorado
ahead of shortwave moving up the western side of the upper ridge.
Combined with plenty of surface based heating...expect these
thunderstorms to continue to drift to the east southeast across the
plains...interacting with high surface dew points (generally in the
50s)...and deep layer shears of around 40-50 kts. Cape values will
probably range around 1000-2000 j/kg...producing a high probability
for supercells...with large hail and damaging winds. LCLs are low
enough to justify threat for an isolated tornado...especially where
surface winds pull more easterly up the Arkansas River valley. Latest
hrrr (11z due to system upgrades and lack of updates) and 4km NSSL
WRF...all peg northern El Paso County with potential for supercell
development...which then drops south southeastward through the
evening. This raises concerns for potential flash
flooding...especially on the Black Forest burn scar...as well as the
Waldo...though models seem to peg Black Forest with the highest
probability. Best threat for this area will range from the 3 PM to
5 PM time frame.
Convection should spread eastward across the plains this evening
with threat for severe weather winding down after 9 PM...and threat
for thunderstorms shifting to the east of the area shortly after
midnight.
Concerns shift towards critical fire weather conditions for
Wednesday as dry airmass moves in from the west with increasing
southwest flow. Current red flag warning still looks on target.
Quick call around to local land management agencies indicates that
fuels along the southern I-25 corridor...Pueblo...Huerfano...and
western Las Animas will carry fire...so have included those zones
into the red flag warning.
Meanwhile...new model runs have backed the dry line westward and
keeps it across the far eastern counties during the afternoon. Quite
a bit of cape out that way with around 2000+j/kg and nam12
indicating 0-6km shears around 40-50 kts...so there will be a
chance for supercells with damaging winds and large hail should a
thunderstorms fire up. Threat looks pretty isolated at this point
as trigger may be missing...but soundings appear to lose the cap
towards afternoon...so convergence and surface heating may be
sufficient to pop a thunderstorm. -Kt
Long term...(wednesday night through tuesday)
issued at 253 PM MDT Tuesday Jun 18 2013
..dangerous fire weather conditions through the extended...
Models agree quite well into and through the weekend. Pattern is
a slow moving upper low over the Pacific northwest and a ridge
across the central US. Our County Warning Area will be under a broad...dry
southwesterly flow with consequent dangerous fire weather
conditions.
Wednesday night...latest model runs show a ribbon of high cape
values across our Kansas border counties early evening...so
reintroduce isolated probability of precipitation. Thereafter...dry conditions will prevail
across the entire County Warning Area.
Thursday and Friday...the upper low over the northwest US will drift
east. Swift southwesterly flow will continue across the central
rockies...producing dangerous fire weather conditions...especially
over the mountains...high valleys...and adjacent plains where mixing
will be greatest and fuels critical. A Fire Weather Watch continues
to be in effect for the mountains...high valleys...and El Paso
County for Thursday. We will likely need fire weather highlights
during Friday. Afternoon high temperatures will be in the upper 90s
to lower 100s expected across the plains. Very dry air will prevent
and moist convection to develop.
The pattern begins to be more progressive this weekend...as the
upper low lifts northeast into south central Canada. Southwesterly
flow will continue...however moisture will begin to move north into the
far southeastern plains. There will be a continued fire weather
threat over the mountains and high valleys through the weekend into
early next week. The long range models develop diurnal convection
across northern New Mexico and move them northeast into the far
southeastern plains. We have low probability of precipitation generally along the New Mexico
border through the weekend as the thunderstorms move into the
Central Plains and clip our far southeast counties. Temperatures will
remain warm with 90s across the lower elevations into early next
week. -Tlm-
&&
Aviation...(for the 06z tafs through 06z Wednesday night)
issued at 1122 PM MDT Tuesday Jun 18 2013
VFR conditions are expected at kcos...kpub and kals tonight and
Wednesday. South to southwest winds are expected to increase by
afternoon with gusts of 20 to 30 kts.
&&
Pub watches/warnings/advisories...
red flag warning from 11 am to 8 PM MDT Wednesday for coz220>230.
Fire Weather Watch from Thursday morning through Thursday
evening for coz220>230.
&&
$$
Update...28
short term...knots
long term...tm
aviation...28
