Scientific Forecaster Discussion
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Area forecast discussion...updated
National Weather Service Fort Worth Texas
100 PM CDT Thu may 25 2017
VFR conditions will prevail this afternoon and evening with gusty
south winds. Some cirrus will invade from the west, but no clouds
are expected within the boundary layer until early Friday morning.
A powerful low-level jet may reach 50kts at 925mb, and MVFR stratus
will race north. A strong cap will limit mixing Friday, but the
late may sun will eventually lift and erode the layer, and
scattered cumulus will prevail from late morning through the afternoon
hours. A dryline may come within 100nm of the metroplex terminals,
which should somewhat reduce the speed and vigor of the winds on
Friday, but there should still be enough momentum from the
decaying low level jet to assure some gusts, particularly as the stratus
thins. The stratus will return again Friday night, likely a couple
hours earlier than the preceding night.
Previous discussion... /issued 346 am CDT Thu may 25 2017/
a rapid warmup will begin today with building upper level high
pressure and the return of Gulf moisture. The pressure gradient
will tighten this afternoon in response to surface Lee troughing
across eastern Colorado. As a result, southerly winds will
increase across north and central Texas between 15 and 25 mph
along with gusts in excess of 30 mph. These speeds are just below
Wind Advisory criteria, so we will forgo issuing one at this
time. There will be plenty of sun today, which when coupled with
the warm air advection, should send temperatures into the middle
80s to the middle 90s.
Moisture recovery today will be the slowest across the western
zones and relative humidities will fall below 30 percent this
afternoon. The hot and dry conditions do raise some fire concerns.
However, recent rainfall has kept the vegetation growing, so the
fire threat should remain relatively low.
The upper ridge will translate east tonight as an upper trough
moves across the western Continental U.S.. the approaching upper trough
will deepen the Central High plains surface trough which will
keep the Gulf wide open. Therefore, tonight will be breezy and
mild with lows in the 70s. Low clouds will also stream northward
from south Texas and The Hill Country overnight and reach North
Texas early Friday morning.
Summer like conditions will return just in time for Memorial
weekend with afternoon highs Friday generally in the 90s. Some
triple digits are also likely across the western zones as the
dryline mixes in and surface winds turn to the southwest. East of
the dryline, dewpoints will remain in the upper 60s and lower 70s
Friday afternoon,so afternoon heat index values will be around
100 in most areas. We don't expect any storms to develop Friday
afternoon due to a Stout cap of warm air between 850 mb and 700 mb
and a lack of large scale forcing.
Saturday will be very similar to Friday with one exception, large
scale lift will increase due to the approaching upper system. The
increasing lift will work to lift and weaken the cap. Therefore,
the mesoscale lift on the dryline may be enough for storms to
develop Saturday afternoon. If any storms do manage to form they
will likely become severe due to high instability (cape on the
order of 5000+ j/kg) and favorable shear. We will still keep pops
low for now since the cap may be difficult to overcome.
Thunderstorm chances will increase Saturday night as the upper
trough moves across the Central Plains and a cold front moves
into North Texas. The best storm chances will be across the
northeast zones in the region of the most favorable upper
dynamics. We have kept pops on the low side (20-30) elsewhere
since the cap may still be a limiting factor.
The front will move slowly through the entire forecast area on
Sunday which will increase precipitation chances. The storms
Sunday will have an added boost from a shortwave approaching from
the Desert Southwest. The front should clear the County Warning Area Sunday
night, but precipitation chances will linger across the southern
zones through Monday as the shortwave translates across the region
and moisture is forced up over the front.
Precipitation chances will decrease Monday night once the
shortwave moves to the east and brief large scale subsidence sets
up. However, shower and thunderstorm chances will increase from
south to north Tuesday through Thursday as the front lifts
northward in response to another low pressure system approaching
from near baja. Energy and moisture associated with this system
have the potential to bring precipitation chances to much of the
region the second half of next week through the weekend.
Preliminary point temps/pops...
Dallas-ft. Worth 90 74 94 77 94 / 0 10 0 5 20
Waco 90 74 93 76 93 / 0 10 0 5 10
Paris 84 69 88 73 88 / 0 10 0 5 20
Denton 90 74 95 76 95 / 0 10 0 5 20
McKinney 87 73 92 76 92 / 0 10 0 5 20
Dallas 90 75 93 78 93 / 0 10 0 5 20
Terrell 87 72 90 76 91 / 0 10 0 5 20
Corsicana 88 73 91 75 91 / 0 10 0 5 10
Temple 90 73 92 75 92 / 0 10 0 5 10
Mineral Wells 94 72 99 75 96 / 0 10 0 5 20