Area Forecast Discussion
Issued by NWS Dallas/Fort Worth, TX

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FXUS64 KFWD 310255 AAB
AFDFWD

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
955 PM CDT MON MAY 30 2016

.UPDATE...
Thunderstorms continue across West Texas this evening but it has
been a much quieter evening across North and Central Texas and it
is expected to stay that way through the night. Will keep a low
chance for rain west of Interstate 35 through the night in case a
rogue shower or storm is able to creep into those counties but the
motion on the storms to our west is erratic without much eastward
movement. The best lift for convection is expected to stay to our
west closer to an upper level trough over southern Arizona.
Otherwise, the current forecast was on track but did adjust sky
cover to account for high level clouds due to anvil debris.

JLDunn

&&

.AVIATION...
/ISSUED 746 PM CDT MON MAY 30 2016/
Minimal aviation weather concerns are expected across North and
Central Texas this evening and overnight with shortwave ridging
aloft and weak flow at the surface. It appears that most of the
thunderstorms this evening and overnight will be on either side of
the upper ridge with the best storm chances across West Texas.
Better storm chances will arrive Tuesday afternoon and evening
when large scale upward forcing increases in response to an upper
low approaching from the southwest. The best storm chances will be
Tuesday evening/overnight when the upper low reaches far West
Texas. These storms will likely begin to impact all North and
Central Texas Terminals just beyond this TAF cycle.

Scattered clouds between 4000 and 6000 ft are expected tonight
through Tuesday afternoon. A 20 to 25 knot low level jet may bring
some brief MVFR ceilings toward sunrise with the best chances
across Central Texas. Any low ceilings that do manage to form
will quickly mix out by mid morning.

79


&&



.PREV DISCUSSION... /ISSUED 345 PM CDT MON MAY 30 2016/
The airmass over the region is pretty worked over from the
overnight and morning convective episode, but afternoon sunshine
has returned and some pockets of enhanced instability have
developed primarily across the far western zones and also eastern
zones. Some isolated slow moving diurnal convection with locally
heavy rainfall will be possible in these areas through early
evening, but would expect this activity to diminish or dissipate
by mid evening with the loss of heating. Otherwise, the synoptic
environment over the region tonight is suggesting that a repeat
round of West Texas storms moving into the region is unlikely.
This is because the mid-upper level westerly winds have weakened
which means cell motions will be much slower, but also the low-mid
level flow has become more westerly which limits the deep layer
shear and ability for convective complexes to organize and track
easterly as well. Most of North and Central Texas will experience
a tranquil evening with temperatures not unpleasant for the time
of the year. However increasing low clouds and low level moisture
by morning will keep lows from falling beyond the upper 60s.

The next upper level shortwave trough will arrive into the Texas
Panhandle and West Texas by midday Tuesday and southerly flow over
our region will once again organize. This will bring rich Gulf
moisture northward and again set the stage for a convectively
active evening and overnight period. While a few showers and
storms may pop up right over the area during the day Tuesday in
the moist and unstable airmass, the main show will develop
northwest of the CWA in the afternoon hours and head southeast
into North Texas during the evening and overnight hours. Instability
will be plentiful and deep layer shear is sufficient for organized
convective modes -- primarily multicell complexes but brief
supercellular structures during the evening hours will be possible
over the NW zones. So a low severe weather threat will occur with
this round of convection, but perhaps more of a concern is the
locally heavy rainfall potential. The topsoils are saturated from
the recent rounds of rain (especially over most of the NW CWA) and
any additional rainfall will be more prone to run off. Average QPF
of 1 to 2 inches appears likely for the northwestern zones and we
may consider a flash flood watch for this area in subsequent
forecast packages. The convection Tuesday night will likely
continue to track southeastward across the region into Wednesday
morning so will continue to show likely PoPs. We may see a
respite in the activity by the afternoon hours, but generally
cloudy conditions will prevail and help to keep high temps around
80 degrees for the first day of June.

The weather pattern will get interesting by Wednesday night as a
cut off upper level low moves into the state from the west. This
low will be vertically stacked, meaning that there will be a low
pressure/height center from the surface to the tropopause in the
same general area. This means the region will be in a persistent
area of upper level lift coincident with a continuous
east/southeast low level feed which will keep precipitable water
values up around 1.9 inches. Meanwhile the temperature gradients
associated with the upper low will weaken which is a sign of a
system transitioning from cold-core to warm-core. These warm-core
lows can sometimes set up a convective feedback loop where
convective episodes serve to enhance the upper level dynamics for
lift which results in more convection...and then more lift...and
so on. This can result in localized regions of very heavy rainfall
particularly during the late night and morning hours. So on the
synoptic scale there is the concern that all of the ingredients
are in place for some excessive rainfall totals somewhere across
Texas for the latter half of the week. Obviously we can`t say
exactly where these areas of heavy rain will set up at this time.
We can say that the due to the lack of baroclinic energy the
severe weather threat will be almost zero, since instability will
be limited and winds will also be fairly light through the
tropospheric column.

For the particulars of the forecast, have indicated good chances
of rain both day and night Wednesday night through Saturday
morning. The cyclone drops southeast into the Gulf during the day
Saturday and allows northerly winds to bring in some drier air
behind a cold front into our region which should gradually end
the rain chances. High temperatures will be below normal -- with
forecast values in the upper 70s to low 80s to start out the first
few days of June.

TR.92



&&


.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    70  87  66  81  67 /  10  30  70  60  50
Waco                68  87  68  80  66 /  10  30  50  60  60
Paris               67  86  68  79  66 /  20  20  60  70  50
Denton              67  86  66  79  65 /  10  40  70  60  50
McKinney            66  86  67  80  66 /  10  30  70  60  50
Dallas              72  87  67  81  67 /  10  30  70  60  50
Terrell             68  87  68  81  66 /  10  30  60  60  50
Corsicana           69  87  68  81  67 /  10  30  50  60  60
Temple              68  85  68  80  67 /  10  30  50  70  60
Mineral Wells       67  84  65  79  65 /  20  40  70  60  50

&&

.FWD Watches/Warnings/Advisories...
None.
&&

$$

79/82


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