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Area Forecast Discussion (AFD)

Issued by Houston/Galveston, TX (HGX)

                            
000
FXUS64 KHGX 180518
AFDHGX

Area Forecast Discussion
National Weather Service Houston/Galveston TX
1218 AM CDT Tue Jun 18 2019

.AVIATION [06Z TAF Issuance]...

VFR. Patchy fog still possible but with increase in 4000ft and
cirrus decks threat trending lower near sunrise. Otherwise no
changes.

45

&&

.PREV DISCUSSION /Issued 630 PM CDT Mon Jun 17 2019/...





.SHORT TERM (Tonight through Tuesday afternoon)...
A broad lower level northern Gulf circulation in association with
an eastern- exiting upper tough axis into the upper Midwest has 
kept the region under a mid to upper level northerly flow pattern.
This has advected in relatively drier air from the Plains and mix
down has lowered northern CWA dew points into the upper 60s to 
coastal lower 70s. Very light precipitation is forming east of 
Galveston Bay and points offshore on the backside of an exiting 
northwestern Gulf weak surface low. While partial clearing of 
early day cirrus has allowed areawide temperatures to warm into 
the lower to middle 80s, it appears that eastern Texas falling on 
the backside of this troughing will keep the day mainly dry. A 
pleasant overnight with possible lower overcast over the Brazos 
River Valley and western county weak winds and partially clear 
skies over somewhat damp ground increasing the near sunrise 
possibility of rural patchy fog. Ambient temperatures approaching
the middle 70s and their respective dew points also increasing 
the chance for early Tuesday interior fog development. 

Weak ridging at all levels on Tuesday will make for a slightly
warmer and mainly dry start to the day. A thin low level or high
veil of cirrus should evaporate enough by Noon to allow surface
temperatures to warm into the upper 80s to lower 90s by 2 or 3 
PM. Moisture levels will not be any higher than they are today 
with southeast Texas still under a northwest to north mid to upper
flow pattern. Weak winds may allow for a better establishment of 
the mesobreezes. If we do receive any measurable precipitation 
tomorrow afternoon it will come along or behind a the sea or bay 
breeze. 31


.LONG TERM (Tuesday night through next Monday)...
Weak upper level ridging will reside over Texas Tuesday night. 
Moisture profiles look meager with PW values falling to below 1.50
inches. On Wednesday despite some modest amplification in the 
upper ridge, 500 mb heights changes very little, however 850 mb 
temperatures begin to warm and reach values between 22 C and 24 C.
This should support high temperatures in the middle 90's. Strong 
capping near 850 mb should preclude much in the way of precip on 
Wednesday and convective temps warm to near 100. Peak heat index 
values on Wednesday will reach 105 degrees which is pretty warm 
for this time of year. 850 mb temperatures warm even more on 
Thursday with temps between 23 C and 25 C and this supports 
surface temperatures in the upper 90's. Moisture profile again 
looks rather meager so not expecting much in the way of 
precipitation. On Friday, 850 temps cool slightly and the flow 
aloft begins to transition to the southwest as an upper level 
trough approaches California. This will allow for a series of 
upper level disturbances to traverse the region Friday night 
through Sunday night. A bit more moisture/cloud cover and subtle 
cooling aloft should allow for slightly cooler surface temperatures.
The proximity of the upper level ridge over the Gulf and the weak
disturbances in the upper flow will be competing with each to see
which feature will exert more influence on area weather. At this 
time will lean toward the embedded disturbances dominating and 
isolated/scattered showers and thunderstorms will be possible both
Sat/Sun. By next Monday, the upper trough over CA moves east into
the central plains and this will allow the upper ridge over the 
gulf to expand into SE TX. This should produce enough subsidence 
to end rain chances and allow temperatures to once again warm up 
into the middle 90's. 43


.MARINE...
A couple of quiet days across the local waters as the dominant
wind will be weak onshore through Wednesday afternoon. There may
be periods of overnight Cautions but Advisory level winds will 
not get ramped up until Thursday and over the weekend. 2 to near 
4 foot significant sea heights will lift to around 5-6 feet 
nearshore to 7-8 feet offshore with 7 to 8 second period swell by
Saturday afternoon. Other than periods of stronger rip currents 
there should not be any immediate coastal hazard in the next few 
days. 31



&&

.PRELIMINARY POINT TEMPS/POPS...

College Station (CLL)  93  76  95  78  97 /   0   0  10  10  10 
Houston (IAH)          93  77  95  79  96 /  10   0  10  10  10 
Galveston (GLS)        88  82  90  83  90 /  10   0  10  10  10 

&&

.HGX WATCHES/WARNINGS/ADVISORIES...

TX...None.
GM...None.

&&

$$


AVIATION...45