Scientific Forecaster Discussion
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Area forecast discussion...updated
National Weather Service Fort Worth Texas
1147 PM CDT sun Apr 20 2014
Shortwave continues to rotate east-northeast across the High Plains
of the Texas Panhandle and Oklahoma and should drive convective
complex mainly across the Red River into southern OK through
sunrise Monday morning. Meanwhile...warm air advection regime shower activity
will continue from the dfw metropolitan through the Red River valley as
well through 1-2 am. Challenges will continue to be timing of
convection throughout the taf forecast and ceilings varying from
VFR...to MVFR...then back to VFR by midday Monday.
Will continue similar trends on all events from 00z issuance. Will
carry some chances for rain through 07-08z at dfw airports...then
only carry vcsh at all airports through middle morning with MVFR
ceilings. Still appears weak outflow will trigger storms between middle-
late afternoon across the region...with a weak cold front/outflow
arriving by middle evening across the dfw area...then at Waco likely
by midnight Tuesday or shortly thereafter. Main window for storms
should be between 21z Monday and 03z Tuesday.
Otherwise...light east-southeast winds 5-10 miles per hour...should become S 10-13 kts
by midday Monday...then veer southwesterly just ahead of the front by 00z
Tuesday...then northwest 7-10 kts behind the cold front Tuesday night.
numerous showers and isolated thunderstorms will continue to move
northeast across North Texas through late evening as a short wave
ejects out ahead of a strong upper low. Showers and storms will
temporarily end from west to east late this evening/overnight.
However...an additional complex of thunderstorms currently moving
across the Low Rolling Plains and southwest Oklahoma will move
east/southeast with the main upper low. The high res models agree for
the most part that these storms will weaken as they move into the
northwest zones of North Texas overnight. However...they should
not dissipate completely since large scale lift will be on the
increase. Therefore...we will leave likely probability of precipitation across the
northern counties overnight.
For this update we will make some minor adjustments to the hourly
wind grids as well as the temperature/dewpoint grids.
Previous discussion... /issued 333 PM CDT sun Apr 20 2014/
a nearly solid area of elevated showers and thunderstorms has
developed this afternoon across parts of northwest Texas. At 3
PM...the activity was bounded roughly by Wichita Falls...
Bridgeport and Abilene. Additional showers and storms were
developing near Coleman and Brownwood. All activity was moving
northeast at around 40 miles per hour. The forecast for tonight will feature
the highest probability of precipitation across the northern areas...with likely category
near the Red River...with only a slight chance in the far south.
Some of these elevated storms could produce small hail along with
frequent lightning...but pose a minimal severe threat. We will
continue to watch for surface-based storm development near the
dryline in West Texas...but chances are that any such strong to
severe storms will diminish drastically before reaching as far
east as Graham or Breckenridge late this evening.
Models are in good agreement that the strong upper forcing for
ascent...associated with the current convective activity...will
begin moving east of the area after midnight. There may be a
minimum in convective activity across the area from 3 am to noon
on Monday. However...we cant rule out at least isolated
development in any area during this time frame given proximity of
upper trough across West Texas and continued ascent from low level
warm air advection.
Breaks in the clouds will lead to moderate to strong instability
developing over much of north and central Texas on Monday
afternoon. With temperatures around 80 and dew points in the low
to middle 60s...surface based cape values should reach 2000 j/kg
locally. Expect scattered to numerous thunderstorms to develop by
early afternoon as mesoscale lift from cold front/wind-shift
crosses the Red River. The strong instability and moderate deep
layer shear of 30 knots will lead to multicell clusters of strong
to severe storms...with a threat for damaging winds and large hail.
Weak low level shear...cell mergers...and relatively strong storm
outflow should limit the tornado threat to the first few hours
after initiation in the early afternoon. The storms will likely
spread east and southeast with the cold front...and gradually
weaken as they concentrate in the east and southeast areas by
Lingering showers in the extreme south will end early Tuesday.
Clearing skies and above normal temperatures are forecast Tuesday
afternoon in the subsident air behind the departing shortwave. Dry
weather will continue through Wednesday afternoon...with lower and
middle 80s forecast for highs in all areas.
Next chances for showers and storms will arrive for the periods
Wednesday night through Thursday night and Friday night through
Sunday. Will keep probability of precipitation on the low side for the middle week system
given only modest forcing at best from a fast moving plains
shortwave. There is more uncertainty with regard to next weekends
system...as medium range models depict a much deeper trough
developing into the southern rockies by late in the weekend. Will
forecast the highest probability of precipitation for North Texas on Sunday Apr 27...but
will go no higher than 30 percent at this time given uncertainties
with timing this far out.
Preliminary point temps/pops...
Dallas-ft. Worth, Texas 62 81 62 82 61 / 50 50 40 5 5
Waco, Texas 60 80 61 82 60 / 20 40 50 5 5
Paris, Texas 59 77 59 79 56 / 60 50 60 5 5
Denton, Texas 60 79 59 82 58 / 50 50 40 5 5
McKinney, Texas 60 77 58 80 57 / 60 50 50 5 5
Dallas, Texas 63 80 62 82 61 / 50 50 50 5 5
Terrell, Texas 60 79 60 81 58 / 40 50 60 5 5
Corsicana, Texas 60 79 61 81 60 / 30 40 60 5 5
Temple, Texas 59 82 61 83 60 / 20 30 50 10 5
Mineral Wells, Texas 61 81 58 82 58 / 40 50 30 5 5