Area forecast discussion
National Weather Service Grand Junction Colorado
328 PM MDT Wednesday may 22 2013
Short term...(this evening through Thursday night)
issued at 327 PM MDT Wednesday may 22 2013
500 mb analysis showing a blocky pattern across the northern tier of
states into the high latitudes of noam. This includes a strong ridge
over the Canadian prairies which will keep low pressure spinning in
the vicinity of the Pacific northwest states well into the late week
period. As a result dry and warm southwesterly flow is expected to be
directed toward our County Warning Area and bring a strong warm up including an
extended period of critical fire weather concerns as highlighted
in the fire section below.
Some cumulus forming from the heating of the day with additional uplift
coming from a wave crossing the southern Utah/Colorado border late
this afternoon. Moderate lapse rates are in place under this
ascent and a few showers/isolated T-storms will continue to be possible
through sunset across the eastern mountains. This looks to be the
best chance for any type of precipitation as Bone dry low layers
will be the normal through the weekend. Gradients across the lower
western valleys look similar to last night with surface low pressure
remaining anchored over the high deserts to the west. This should
allow for good downvalley flow wtih forecast lows toward the warm
side of guidance.
Thursday strong heating will again be taking place as the thermal
ridge remains overhead. A stronger core of middle level winds will be
moving over eastern Utah into western Colorado tomorrow. Efficient
mixing will bring the warm air to the surface as temperatures
move into the lower 80s. Persistent drought conditions...with a
recent lack of significant rainfall should combine with the strong
mixed layer to produce well above normal temperatures tomorrow.
Average temperature for 90 degrees in the valley is 31 may...and
we will be approaching this tomorrow...so pushed the forecast maximum
temperatures closer on the high side of guidance. Some of this
guidance still pushing winds toward Wind Advisory criteria over
the eastern Utah valleys and BUFKIT shows a fully mixed profile
bringing gusts near 45 miles per hour down to the surface. Confidence low for
widespread conditions so no headlines at this time. Expect some cumulus/MDT cumulus
developement over the hills tomorrow but little chance of precipitation
hitting the ground. The surface gradient slackens Thursday night which
should lead to lighter terrain driven winds in many areas. Expect
little humidity recovery but winds should be dropping off over all
but the highest terrain. Dry air...clear skies and lighter winds
will also drop lows by a few degrees.
Long term...(friday through wednesday)
issued at 327 PM MDT Wednesday may 22 2013
The large scale pattern remains very consistent through
the long term...with a mean trough near the West Coast and a ridge
on the plains. The models all hint at some slow progression of this
pattern early next week with the ec slowest...the Canadian
fastest...and the GFS in between.
At least through Monday dry and warm and breezy conditions will
continue each afternoon. High clouds may play with temperatures but
afternoons are expected to be 7-10 degrees above normal with morning
lows closer to normal. Long term guidance was modified for more
persistent temperatures and dewpoints. The warm afternoon
temperatures will allow mixing up to 500mb or more which will
produce gusty late-day southwest winds. Critical fire weather
conditions remain a concern well into next week.
As the trough works towards the forecast area sometime next week...
daytime temperatures should modify and chance of showers increase.
Timing of this is uncertain.
&&
Aviation...(for the 00z tafs through 00z Thursday evening)
issued at 327 PM MDT Wednesday may 22 2013
VFR conditions will remain in place across eastern Utah and
western Colorado over the next 24 hours. Unstable conditions and a
bit of moisture over The Divide mountains of Colorado will keep convection
in place through sunset. Gusty winds will be the main threat to
the kege and kase terminals near this convection...however
limited flight criteria are not anticipated at this time.
Southwest winds will be increasing overnight into Thursday and may
bring local low level wind shear in the Thursday morning due to
down valley flow. Frequent wind gusts over 25 miles per hour can be expected
by early Thursday afternoon.
&&
Fire weather...
issued at 327 PM MDT Wednesday may 22 2013
A trough of low pressure will remain anchored near
the West Coast well into next week. This will produce gusty
southwest daytime winds...above normal temperatures...and low
relative humidities each day. Fuels are critical across most of
southwest Colorado...thus red flag warnings are in effect for
Thursday afternoon and early evening. These critical fire weather
conditions are expected to continue into early next week.
&&
Gjt watches/warnings/advisories...
Colorado...red flag warning from noon to 9 PM MDT Thursday for coz207-290-
292-293.
Utah...none.
&&
$$
Short term...15
long term...Joe
aviation...15
fire weather...Joe
