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

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FXUS64 KFWD 272055

Area Forecast Discussion
National Weather Service Fort Worth TX
355 PM CDT WED JUL 27 2016

The main highlights for this forecast package will be rain
chances over the next several days and into the early portion of
the weekend. For the latter half of the weekend and into next
week, the upper air pattern favors one that should result in hot
and mostly dry conditions.

For the rest of this afternoon, showers and thunderstorms will
continue as daytime heating and additional convection develops
along outflow boundaries. The main culprits for convection this
afternoon are the mid-level deformation axis as seen in water
vapor imagery and RAP H5 fields across North TX with the main
impetus for convection across Central TX being along modified sea-
breeze outflow lifting northward. The very moist regime, slow
storm motion and weak deep layer shear has resulted in efficient
rain producers across North and Central TX this afternoon.

There have been a few strong convective outflows, but generally
the moist environment makes has made it a bit more difficult to
generate a large amount of negative buoyancy within and below the
convective clouds. That being said, we will maintain a risk for
generally sub-severe downbursts as precipitation loading may
result in winds in the 40 to 50 MPH range. One area that we will
watch will be across southeastern zones where sufficient heating
and a bit more in the way of mid-level dry air exists. This may
promote a slightly higher risk for downbursts across this part of
North and Central TX.

Convection for the most part should wane through the evening
hours before subsiding with the loss of daytime heating. I will
maintain slight chance PoPs (with higher chances across NE zones)
as most of the synoptic models show a shift in the upper air
pattern. This shift places much of the forecast area in northerly
to northwest flow aloft. Most models advertise some DCVA in the
north to northwest flow aloft and given the moist regime, this
warrants at least keeping slight chance PoPs across the area.
Convection is expected to continue Thursday morning across much of
the area as shortwave troughs traverse the north/northwest flow
aloft. The airmass is expected to remain rich and moist and as a
result, instances of minor flooding will be the main risk with
showers and thunderstorms. Similar to today, there will be a gusty
downburst wind threat, but poor lapse rates and generally modest
wind shear should limit overall storm organization.

Rain chances will continue into Friday and Saturday as the swift
north/northwest flow pattern continues. 20-30 percent PoPs were
introduced Friday afternoon into Saturday morning given that a
few lobes of mid/upper level vorticity are forecast to sweep
through the area.

Beyond Saturday, near triple digit heat is expected to grip North
and Central TX. Wind speeds are generally expected to be fairly
light through this portion of the forecast. The weak winds should
prevent deep boundary layer mixing. As a result, relative
humidities will continue to range in the mid-30 to 40 percent
range. While this may limit a larger fire weather concern for
areas that miss out on rain over the next several days, heat
index values will likely climb back into the 102 to near 105
degree range.



/ISSUED 1255 PM CDT WED JUL 27 2016/
/18Z TAFS/

As expected, two areas of convection are being monitored. Both the
HRRR and TTU WRF have been good with initiation of isolated-
scattered showers and storms developing within an are of mid level
deformation and high moisture content west-northeast from DFW
currently. The other area I`m watching is outflow coming up into
central TX. Highest concentration of activity is currently
between Gainesville and Bonham, which should eventually push an
outflow boundary southward toward the DFW terminals between now
and 4 pm. Have carried a 3-hr TEMPO group for MVFR -TSRA and
variable gusty winds to 30 kts or so.

We should see outflow come through before 22Z and push better
convective chances south of DFW with better chances focusing on
central TX and Waco from 22Z through sunset. Confidence is good
on some convection around, but timing or length of time of
persistence of convection is not high. Environmentally, south-
southeast winds will prevail 5-10 kts, with the exception of a
brief outflow surge by 20Z-21Z that should wash out by 00Z over
DFW airports. AWW has been issued current for lightning through
20Z/3 pm cdt.

Beyond nightfall into tonight, deformation area shifts south and
could see latent heat release redevelop pre-dawn convection along
and south of I-20 by sunrise. Confidence here is very iffy, but
have a mention of VCTS at Waco where probabilities are higher for
TSRA with just VCSH at DFW airports for now.



Dallas-Ft. Worth    76  94  77  97  78 /  50  40  10  30  20
Waco                77  97  75  99  76 /  30  40  20  20  10
Paris               73  90  73  94  74 /  50  40  20  30  20
Denton              73  93  74  96  74 /  60  40  10  30  20
McKinney            74  93  75  95  75 /  50  40  10  30  20
Dallas              77  94  76  98  79 /  50  40  10  30  20
Terrell             75  93  75  95  76 /  40  40  20  30  20
Corsicana           76  96  75  96  77 /  30  40  20  20  10
Temple              75  96  75  97  75 /  30  40  20  20  10
Mineral Wells       72  94  72  97  73 /  50  40   5  20  10


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