Forecast Discussion for Dallas/Ft. Worth, Texas

FXUS64 KFWD 071105

Area Forecast Discussion
National Weather Service Fort Worth TX
605 AM CDT Tue Jul 7 2020


Showers and thunderstorms have started to increase in coverage
this morning mainly south of I-20. The main area of concern in the
immediate short term is across parts of Henderson and Anderson
counties where a cluster of slow moving thunderstorms has now
produced over 4" of rain in the last two hours. Multi-sensor radar
reflectivity at the -10C level reveals reflectivity values mainly
in the 35-45 dBZ range indicative of some warm rain processes with
little ice. Lightning data supports this idea with overall
lightning activity not as impressive as some of the more scattered
convection to the west. This cluster will continue to pose a
localized flash flood threat through the morning. Additional cell
mergers and echo training throughout the remainder of today could
also result in some isolated rainfall totals in excess of 4".

For the rest of today, little change was made to the current
forecast other than to tweak PoPs down a little across our
northern counties and really try to confine the highest PoPs to
the strongest theta-e gradient. This gradient is roughly oriented
west to east from Killeen to Waco to Athens, but should every so
slowly spread northward into the afternoon. Higher rain chances
should spread as far north as I-20/30 before tapering off north
and northwest of there through the remainder of the afternoon.
During peak heating, we`ll see another expansion in coverage of
scattered thunderstorms with diminishing coverage into the
evening hours. Rain chances will gradually shift eastward into the
overnight hours and on Wednesday.

We also lowered high temperatures a few degrees today mainly east
of I-35 where more extensive cloud cover will be present along
with the better rain chances. No other significant changes at this



Previous Discussion:
/Overnight through Wednesday/

The large area of precipitation from earlier this evening
continues to diminish in intensity and coverage as it moves into
East Texas. In its wake, a relatively small area of more stable
air is in place just to the south of the Metroplex, but this will
likely recover fairly quickly. Satellite estimates of total
precipitable water continue to indicate >2" PWs extend back as far
west as Mineral Wells with a likely small reduction in the wake of
earlier precipitation.

A rough surface analysis indicates one main outflow boundary that
has pushed to the south of I-20 and is in the vicinity of Waco as
indicated by a tighter theta-e gradient and very subtle wind
shift. Farther to the north, another outflow boundary has pushed
to the northwest of the Metroplex. Our old synoptic front may be
lined up somewhere near the Red River, but this may be grasping
at straws. New convective development will likely be tied to weak
ascent associated with a weakness in the mid level height fields
and convergence along old outflows. This appears most likely from
the Metroplex southward during the remainder of the overnight into
the early morning hours. We`ve nudged PoPs just a touch farther
to the north and a little higher than the latest runs of the
HRRR/RAP and other high res guidance, based on the fact that there
does appear to be an old outflow boundary extending from Mineral
Wells to Fort Worth to Denton. We`ll see if any convection can
develop along this feature overnight.

Otherwise, as we get into some heating of the day on Tuesday, we
should see another expansion of convection generally tied to the
same areas mentioned above. We`ll have the highest PoPs right
along the I-20 corridor into East Texas. A gradual shift eastward
with convection is expected through the late afternoon and evening
hours. By Tuesday night into early Wednesday, the mid level height
weakness will shift to the east taking the plume of higher
moisture content with it. We`ll hang on to some low PoPs overnight
Tuesday night and confine them to our far eastern counties on
Wednesday. Highs today will top out in the upper 80s and lower 90s
while they climb back into the mid 90s for Wednesday.



.LONG TERM... /Issued 332 AM CDT Tue Jul 7 2020/
/Wednesday Night through next Tuesday/

A warming trend, with triple-digit heat by the weekend, is
expected across North and Central Texas as the upper level high
across the Southwest strengthens and expands east. Although model
guidance attempts to send a pair of impulses from the Central
Plains late this week and weekend, the upper level pattern should
keep our region free of precipitation as any convection moves
south/southeast along the periphery of the high.

Afternoon temperatures on Thursday and Friday will warm into the
mid to upper 90s, although our far western counties may reach the
century-mark on Friday. With dewpoints in the low to mid 70s, heat
index values will be near 104-108 degrees in a few locales on
Friday. As we head into the weekend, triple-digit high temperatures
and oppressive summer heat is expected due to the combination of
low-level southwesterly flow and subsidence from the upper level
high. Heat indices will range from the low 100s to near 112
degrees regionwide. A heat advisory will likely be needed for most
of North and Central Texas this weekend and possibly early next
week as the triple-digit heat persists into mid July.



/12Z TAFs/

VFR should prevail outside of thunderstorm areas today at all
sites. Over the last couple of hours, LIFR cigs have developed
mainly to the north and northwest of the Metroplex. These low cigs
appear to be in the slightly cooler air to the north of a
stationary frontal boundary. At this time, we think most of this
will stay north of the boundary and not impact any Metroplex
airports, but Alliance would be the closest.

Otherwise, the main concern will be the potential for
thunderstorms this morning and again this afternoon. We should see
an uptick in thunderstorm development over the next few hours,
although most of this activity may be just south and east of
DFW/DAL/GKY. For now, we`ll continue with a VCTS for a few hours
this morning with another VCTS later this afternoon during peak



Dallas-Ft. Worth    87  75  94  78  96 /  50  20   5   0   0
Waco                88  75  95  76  98 /  50  20   5   0   0
Paris               83  72  89  74  92 /  50  20  30   5   0
Denton              87  74  94  76  95 /  40  20   5   0   0
McKinney            87  74  93  76  95 /  50  20  10   0   0
Dallas              87  76  94  78  96 /  60  20  10   0   0
Terrell             85  74  92  75  95 /  70  20  20   0   0
Corsicana           85  74  92  76  95 /  80  20  10   0   0
Temple              90  75  96  76  98 /  40  20   5   0   0
Mineral Wells       88  73  94  75  96 /  30  20   5   0   0





NWS FWD Office Area Forecast Discussion