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Area Forecast Discussion (AFD)

Issued by Houston/Galveston, TX (HGX)

                            
000
FXUS64 KHGX 161159
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
559 AM CST Sat Feb 16 2019

.DISCUSSION [12Z TAF ISSUANCE]...

Areas of patchy to dense fog continues to prevail across portions
of the forecast area, particularly across the southern counties 
and coastal regions of the CWA. Expect LIFR to IFR conditions to 
prevail across KGLS, KLBX, KSGR and KHOU through at least 15Z and 
MVFR to VFR across the rest of the TAF sites. A weak front will 
stall across the region today resulting in N winds through this 
afternoon across all TAF sites, expect KLBX and KGLS where NE to E
winds are expected. Winds will then become more SW to W tonight 
as a cold front approaches the region. Mostly MVFR ceilings are 
expected today...lowering to LIFR/IFR this afternoon and evening 
with areas of fog re-developing across the forecast area. Areas of
dense fog is possible across KGLS and KLBX due to sea fog 
formation.

&&

.PREV DISCUSSION... /ISSUED 449 AM CST Sat Feb 16 2019/ 

DISCUSSION...
SHort term issues...fog and dense fog along and south of the
front. At 4 am the front was near a Columbus to Conroe to
Livingston line creeping southward. Have the Dense Fog Advisory
staggered so the northern areas clear out around 5 am then the
coastal counties 9 am and immediate coast around 11 am but the
immediate coastal areas are going to need some tender loving care
today as the models differ in the limit of the southward
progression of the front. Currently thinking it is going to slow
dramatically around sunrise and won't push off the coast but stall
over Galveston Bay and probably waffle around near Pearland-
Wharton line. As such this could lead to an extension of the dense
fog advisory for the marine areas and coast if it doesn't warm up
and mix out the fog for 3-5 hours late this morning and this 
afternoon. Surface low in South Texas start to retreat northwest
late this afternoon/evening in the wake of the s/w passing by this
afternoon to the north/northeast. This should set the stage for
the front to drift back north this evening but it is short lived
with the next s/w in the fast nearly zonal flow aloft. This next
shortwave will push the cold front south and through the northern 
areas after midnight and probably all the way into the Houston
Metro by 6 am Sunday. Instability looks slim and will probably get
some patchy light rain/showers as well as fog south of the frontal
boundary. The front should push off the coast between 6 and 9 am
Sunday ending the fog at the coast ushering in light northerly
winds with drying. Cloud cover though which is widespread this
morning will likely remain a fixture through Sunday even though 
the lower levels dry out the mid and upper level moisture will 
continue to stream over the area. The broad upper troughing over 
the SW U.S. will maintain the very moist Pacific upper flow over 
SETX and as it slowly shifts eastward pressures in West TX/Mexico 
fall which will help to pull the stationary front over the Gulf 
back north and will lead to increasing rain chances late Monday 
through Tuesday with a coastal trough (probably some 
thunderstorms mixed in with the elevated instability). The front 
will probably waffle about over the Gulf and not make it back 
well inland but could over the coastal areas yielding a very 
favorable environment for isentropic upglide...or another way of 
saying gray, cloudy, damp and rainy weather...Tuesday through 
Friday. Temperatures will run on the cool side of normal for this 
time of year. At this point it looks as though next Saturday could
be more active with the trough shifting east and into the 
state...with showers and thunderstorms in the warm sector arcing 
up through the region drying out Sunday in the wake of a Pacific 
cold front. 
45

MARINE...
Sea fog will continue to affect the bays and nearshore waters early 
this morning. The dense fog advisory continues in effect through 11 
AM CST this morning. Fog is expected to improve during the morning 
hours but could re-develop again in the evening/night hours. Fog 
will dissipate as a cold front moves across the region Sunday. Also, 
an increase in winds and as a result building seas, is expected in 
the wake of the cold front as pressure gradient tightens across the 
Gulf waters. This will result in hazardous marine conditions and 
SCEC/SCA flags will likely be issued late Sunday night through 
Tuesday morning. On Tuesday, onshore wind flow returns and a coastal 
low moves from the lower TX coast into the local waters increasing 
shower and thunderstorm activity Tuesday. Thereafter, an upper level 
trough will move across the region resulting in moderate to fresh 
north to northwest winds Tuesday night and Wednesday. Moderate 
northeast winds are expected to settle in Thursday and Friday. 24

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      56  53  67  43  61 /   0  10   0   0  10 
Houston (IAH)              67  61  71  48  63 /  10  20  10  10  20 
Galveston (GLS)            65  62  68  53  58 /  20  20  30  10  40 

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Dense Fog Advisory until 11 AM CST this morning for the 
     following zones: Brazoria Islands...Coastal Brazoria...
     Coastal Galveston...Coastal Jackson...Coastal Matagorda...
     Galveston Island and Bolivar Peninsula...Matagorda Islands.

     Dense Fog Advisory until 9 AM CST this morning for the following 
     zones: Chambers...Fort Bend...Inland Brazoria...Inland 
     Galveston...Inland Jackson...Inland Matagorda...Wharton.

GM...Dense Fog Advisory until 11 AM CST this morning for the 
     following zones: Coastal waters from Freeport to Matagorda 
     Ship Channel TX out 20 NM...Coastal waters from High Island 
     to Freeport TX out 20 NM...Galveston Bay...Matagorda Bay.

&&

$$

Discussion...45
Aviation/Marine...24