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Area Forecast Discussion (AFD)

Issued by Brownsville/Rio Grande Valley, TX (BRO)

                            
000
FXUS64 KBRO 160856
AFDBRO

Area Forecast Discussion
National Weather Service Brownsville TX
356 AM CDT Thu May 16 2019

.SHORT TERM (Now through Friday): Mid level trough axis slowly works 
off the coast today, as high pressure begins to build across Texas. 
Continuing the isolated wording for a thunderstorm or two across the 
CWA this afternoon, this time favored slightly more toward the mid 
and lower RGV. Convective models persist with a solution similar to 
yesterday, with small slower moving cells popping during the mid 
afternoon. Better chances for development exist south of the border 
where convergence is best. 

The combination of any outflow boundaries from Mexican convection 
with any seabreeze boundaries across Deep South Texas mid afternoon 
could be enough for the initiation of a small handful of storms. 
PWAT values across the mid and lower valley approach 1.75 inches 
this afternoon, allowing any thunderstorm to potentially contain 
locally heavy rainfall. As we saw with the development in Brooks 
County yesterday, hail would also be a threat with any thunderstorm. 
Again, confidence is still low, and a number of factors must come 
into play, so have kept POPs at 20 percent. More stable conditions 
follow by this evening through Friday as high pressure takes 
control. 

Temperatures warm through the short term period, remaining near to 
slightly above normal, with light to moderate ESE winds. Have kept 
patchy fog wording in this package again tonight and partially 
tomorrow night with higher low level moisture sticking around. 
Narrow beaches are a possibility near high tide early this 
afternoon, with tides running nearly 1.5 feet above normal. Do not 
anticipate the need for a headline or statement at this time, but 
will continue to monitor. 

.LONG TERM (Friday Night through Wednesday): The forecast period 
starts with mid level ridging overhead and surface high pressure 
across the Gulf of Mexico. The 500 mb ridge axis moves east over
the western Gulf of Mexico early Saturday as a deep mid level 
trough swings into the Four Corners region. As the trough pushes 
east, the associated surface cold front moves into West Texas 
toward the dry line on Saturday. Some drier air may move into 
the western portions of the CWA on Saturday. The 500 mb trough to
the north will eject northeast into the Plains Saturday night and
Sunday. 

Surface low pressure will develop across West Texas into the 
Plains Monday through Tuesday. This will allow the pressure gradient
to strengthen across deep south Texas with breezy to windy south 
to southeast winds Monday and Tuesday. As the next upper level 
storm system tracks west to east over north Texas, it looks like 
most of the stronger weather will avoid the region. There is a 
slight chance of thunderstorms across the ranchlands Saturday and 
Saturday night. Otherwise, rain-free conditions should prevail 
across the area through the period. Temperatures will be slightly 
above normal, and may trend further upward a few degrees through 
the period.

&&

.MARINE (Now through Friday): With high pressure beginning to build 
across the lower Texas coast today into tonight, expect seas of 
generally 2 to 3 feet to continue. Southeasterly winds increase 
slightly heading into Friday afternoon, allowing seas to gradually 
build toward 3 to 4 feet. Small Craft Exercise Caution conditions 
are possible across the Laguna Madre and offshore Gulf of Mexico 
waters this afternoon and again on Friday due to increased winds. At 
this time, conditions appear to be just below SCA criteria through 
the short term period, however, will need to be monitored late 
Friday. 

Friday night through Monday night: Moderate winds and seas are 
expected through much of the period as the pressure gradient 
gradually strenghtens. Small craft should exercise caution to 
low end small craft advisory conditions will be possible for the 
Laguna Madre and the Gulf waters Friday night into Saturday. Small
craft advisories are likely on all waters Monday into Tuesday as 
winds increase and seas build.

&&

.PRELIMINARY POINT TEMPS/POPS...
BAYVIEW/PORT ISABEL  84  75  85  76 /  20  10  10  10 
BROWNSVILLE          88  75  90  77 /  20  10  10  10 
HARLINGEN            88  74  91  75 /  20  10  10  10 
MCALLEN              92  75  92  76 /  20  10  10  10 
RIO GRANDE CITY      93  74  93  74 /  10  10  10   0 
SOUTH PADRE ISLAND   82  76  83  77 /  20  10  10  10 

&&

.BRO WATCHES/WARNINGS/ADVISORIES...
TX...None.
GM...None.
&&

$$

This product is also available on the web at:
HTTP://WEATHER.GOV/RGV

Short Term...56
Long Term...63 
Graphicast/Upper Air...67