Sunday, January 24, 2021

Jan. 24 21

 Area Forecast Discussion

Issued by NWS Houston/Galveston, TX

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000
FXUS64 KHGX 242343
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
543 PM CST Sun Jan 24 2021

.AVIATION...
Expecting a mix of MVFR/IFR cigs overnight and perhaps a few streamer
shra. Winds should remain up enough to mitigate dense fog inland,
but still cannot rule out some low vsbys around the Galveston Bay
area in association with patches of sea fog. Pacific cold front
will be moving into the region from wnw-to-ese during the mid
morning thru late afternoon hours. Will probably see some -ra/shra
ahead of the boundary, but not much of significance in regards to
intensity. Conditions will transition to VFR a few hours after
fropa as drier air begins moving in.  47

&&

.PREV DISCUSSION... /ISSUED 343 PM CST Sun Jan 24 2021/
SHORT TERM [through Monday Night]...
While skies have remained generally overcast this afternoon, the
area experienced a significant improvement in visibility
conditions during the day today with the coast now remaining
almost clear of fog. This rest will only be momentary, however,
with another night of potentially dense fog in store. With surface
pressures deepening over western TX and the gradient tightening
over SE TX, onshore flow has increased in strength this afternoon
which has proved favorable for the development of isolated showers
across the northern half of the area today. This has also allowed
for dew points to reach the upper 60s at most locations. This
ample moisture is expected to favor fog development after sunset
once again as sea surface temperatures in Galveston Bay are
holding at around 60F and southerly flow is persisting. Both SREF
probabilistic guidance and forecast soundings have indicated the
redevelopment of sea fog after sunset, which could be dense at
times. However, the stronger wind speeds overnight tonight may
work to hamper development slightly. With overcast skies
continuing to inhibit radiative cooling overnight, lows are
expected to stay in the mid to upper 60s.

A pattern shift, likely welcomed by many, is anticipated tomorrow as
the developing surface low pushes northeastward while its associated
cold frontal boundary advances through SE Texas during the day. The
boundary should reach the Brazos Valley after sunrise tomorrow, the
Houston metro by late morning, and the coast by late afternoon.
Showers with some isolated thunderstorms are expected along and
ahead of the boundary. As the front departs during the evening hours
and continues to push offshore, a shift to northwest winds in its
wake will allow for a cooler and drier airmass to take hold over the
area. This should put an end to the prolonged fog event in recent
days and produce nighttime lows in the upper 40s to mid 50s tomorrow.

Cady

LONG TERM [Tuesday Through Sunday]...
In the wake of the cold front on Monday, Tuesday`s light
northerly flow brings in cooler temperatures with morning lows
around 50. Highs will still reach the mid 70s with mostly sunny
skies and winds shifting easterly through the day. A cold front
Wednesday morning will make way for high pressure and
northwesterly flow. Profiles show the frontal boundary relatively
dry and PWATs peak at around an inch. POPs are increased during
frontal passage, but only traces amount of rainfall are expected,
if any, and the greatest threat will be along the coastline. The
increase in cloud cover will prevent much cooling, keeping lows in
the low to mid 50s and the highs right around 70.

The end of the week will be dominated by high pressure with a dry
northerly flow turning to a easterly flow on Friday. Highs will
reach the mid 60s and lows in the mid 40s with low 50s along the
coast. During the weekend, a warm front off the gulf will bring warm
southerly flow and increasing cloud coverage. Rain chances increase,
during cold frontal passage, but trends are suggesting another dry
and weak system. Lows will reach low to mid 50s and highs around 70.

35

MARINE...
Stout southerly flow in place and mixing has gotten rid of the
thickest of the sea fog. As temperatures cool down expect some
patchy sea fog to form over the coldest of the shelf/bay waters
late this evening then after midnight may grow in areal coverage
but will be a fine line between becoming dense. Will let the
evening shift make the call on it based on latest obs. Seas-winds
building tonight and SCEC/SCA already hoisted. Cold front surging
southward at 3 pm near Childress and should sweep into the coast
around 1-3 pm Monday and then through the Gulf waters by 5 pm.
Could see some showers with the frontal passage. Winds post
frontal are not very strong and quickly turn from northwest to
northeast. Next upper trough moves closer and a stronger cold
front swings through on Wednesday. This will set up a persistent
offshore flow that will approach 20 knots sustained so long lived
SCA-SCEC conditions on tap through early Friday. Southerlies
return and strengthen Friday night/Saturday morning and this could
spell a brief period of sea fog before the next cold front on
Sunday.

45

&&

.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL)      63  72  46  74  48 /  50  60   0   0   0
Houston (IAH)              67  75  51  73  54 /  40  50   0   0   0
Galveston (GLS)            64  70  57  65  58 /  30  50  10   0  30

&&

.HGX WATCHES/WARNINGS/ADVISORIES...
TX...Dense Fog Advisory until 6 PM CST this evening for the following
     zones: Brazoria Islands...Galveston Island and Bolivar
     Peninsula.

GM...Small Craft Advisory until 1 PM CST Monday for the following
     zones: Waters from Freeport to Matagorda Ship Channel TX
     from 20 to 60 NM...Waters from High Island to Freeport TX
     from 20 to 60 NM.

&&

$$

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