Area Forecast Discussion
Issued by NWS Houston/Galveston, TX
FXUS64 KHGX 191156
Area Forecast Discussion
National Weather Service Houston/Galveston TX
556 AM CST Thu Jan 19 2017
Radar shows shower activity and a few isolated thunderstorms
moving into the Houston area from the SW as an upper level trough
axis begins to move through the region. Lift from the trough is
acting to enhance the convection so added VCTS/TSRA to TAFs to
start. Activity appears to be moving faster than what progs
suggest so the activity could be ending earlier than 15Z. This
will also depend upon how far back to the west activity develops.
Ceilings will remain at IFR/LIFR levels and could improve with the
onset of convection. Even then ceilings will be a mix of IFR/MVFR
through much of the morning. Ceilings should improve to MVFR in
the afternoon with maybe some VFR at KCLL.
Light winds tonight with moist grounds should lead to fog
development. Models and SREF probabilities all have a strong
signal for fog so added at least a tempo group for 1/2SM fog and
IFR/LIFR ceilings. Quite possible that ceilings and fog will be
slow to improve Friday morning.
.PREV DISCUSSION... /ISSUED 359 AM CST Thu Jan 19 2017/
Rain and thunderstorms are possible once again today over SE
Texas. Do not expect a repeat of yesterday`s rainfall event give
that the frontal boundary was off of the coast early this morning.
However, the area will again come under the influence of an upper
trough moving overhead and the right-rear quadrant of the upper
level jet maximum which in turn will help generate showers and
thunderstorms once again mainly this morning. A radar mosiac at
3:30 AM showed an area of rain and thunderstorms stretching from
the Rio Grande to just west of Columbus. Another area of showers
were moving over the coastal counties. Model estimates are for
about one-quarter to one-half of an inch of total rainfall today
mainly along and east of a line from Columbus to Houston to
Cleveland. With PWs about 1.5 inches (in the 90th percentile for
this time of year), isolated totals of about one inch could occur.
Over the northern portions of the forecast area, rainfall totals
under a quarter of an inch are expected.
Friday and Saturday will be warmer. An upper level shortwave
ridge will move overhead on Friday with an upper low pressure
trough then moving overhead on Saturday. As this system moves east
of the area, it will wrap up and tighten the surface pressure
gradient over SE Texas and breezy conditions will result on
Sunday. A couple of dry days are then in store before another
upper level low pressure trough moves into the Plains over the mid
week period. Ahead of this system, chances for showers and
thunderstorms will arrive Tuesday night and Wednesday over at
least the eastern portions of the forecast area.
Light NW to W winds should continue this morning but then turn SW
for the afternoon. This should allow for low seas to persist. Winds
light southerly winds continue Friday and Saturday with low seas. A
strong cold front should push off the Upper Texas Coast Saturday
night. Winds shift to the NW and increase dramatically Sunday
morning. Gale force winds will be likely Sunday so will likely need a
gale watch at some point. Small craft advisories may be needed
Sunday night into Monday as winds decrease. Seas should quickly
build in response to the strong northwest winds with 9 to 12 feet
seas by Sunday night. Seas should drop below 7 feet by Monday
Tide levels should remain about a foot above normal but could drop
some with light southerly winds into the weekend. Tide levels should
decrease quickly with the passage of the cold front Saturday night.
Low water advisory may be needed given the NW direction of the winds
and the rapid increase in wind speeds.
Overall rainfall from the last couple of days should keep vegetation
and soils moist. Fuels may dry some as a much drier airmass moves
into SE Texas Sunday behind a cold front Saturday night. But
relative humidity levels may only reach 35 percent Sunday with the
strong winds. Humidity levels may be lower on Monday but winds will
be light to moderate. At this time even elevated fire weather
conditions are not expected.
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 68 55 77 57 74 / 30 0 10 20 20
Houston (IAH) 66 58 78 61 76 / 70 0 10 40 30
Galveston (GLS) 64 62 72 64 73 / 70 0 30 50 30