874 
fxus64 klch 070529 
afdlch 


Area forecast discussion 
National Weather Service Lake Charles la 
1129 PM CST Friday Nov 6 2009 


Discussion... 


Radiational cooling will chill the nocturnal boundary layer 
trapping moisture near the surface. Patch fog possible during the 
overnight hours. 


&& 


Previous discussion... /issued 1116 PM CST Friday Nov 6 2009/ 


Update... 
strong high pressure appears to have settled over the East 
Coast...with strong ridging across most of the Gulf states. This 
has allowed for light winds to calm across the region this 
evening...temperatures falling near expected morning lows. Thus...updated 
forecast to bump down temperatures a category across the entire 
region...now expecting middle 40s across c la...upper 40s/near 50 
along the I-10 corridor from lft to lch...and lower 50s across southeast 
Texas. Also...with the added radiational cooling...patchy fog is 
developing...and will likely persist through sunrise. Not expecting a 
widespread dense fog event though. 


With the pressure gradient continuing to increase across the c and 
north Gulf...winds are gradually increasing across this region...although 
below Small Craft Advisory criteria for our coastal waters a the moment. 


However...this large easterly fetch across the Gulf is beginning 
to exhibit water pileup across portions of our region...as tides 
are already running about 1-1.5 feet above predicted astronomical 
tides this evening. This is yielding a total tide near 3 feet at 
Cameron and likely at Sabine Pass (gage inoperative)...and 2.5 
feet at Cypremort Point. With the winds expected to increase 
across the central and northern Gulf on Saturday and Sunday...tides 
could further increase. This could result in tide levels running 
about one and one half feet above the predicted astronomical 
tides...with actual tide levels reaching between 3.5 and 4 feet 
during the high tide cycles Saturday and Sunday evenings...resulting 
in the potential for coastal flooding at these times. 


The biggest question will be the wind direction. If it shifts more 
northeasterly...the potential for coastal flooding will be less. 
However...if it remains easterly as the winds strengthen Saturday...the 
threat for coastal flooding for Vermilion...Cameron...and 
Jefferson/Orange will be greatly enhanced. Thus...issued a coastal 
Flood Watch for Vermilion & Cameron parishes in SW la...and 
Jefferson and Orange counties in southeast Texas. 


Continued coastal flood statement for Iberia and St. Mary parishes 
for tides reaching 2.5 to possibly 3.5 feet Sat. Dont expect as 
much water pileup due to the west-northwest to east-southeast orientation the coastline 
there in relation to the wind direction. 


Dml 


Previous discussion... /issued 530 PM CST Friday Nov 6 2009/ 


Discussion... 


Dome of high pressure across central Louisiana will travel east 
into southern Mississippi by Saturday morning. Patchy radiation 
fog is possible tonight. 


Previous discussion... /issued 406 PM CST Friday Nov 6 2009/ 


Synopsis... 
water vapor imagery and upper air analysis shows flat upper ridge 
migrating east over the area. Over the Gulf of Mexico...a large 
plume of moisture is spreading north in association with a 
developing low pressure area in the Bay of Campeche. At the 
surface...high pressure centered over the southeastern states is ridging over 
the area...providing a nice afternoon with mostly sunny skies and 
temperatures in the middle 70s. 


Discussion... 
one more day of nice weather expected before things deteriorate 
late in the weekend. High pressure will remain in control at the 
surface and aloft for tonight into Saturday. This will allow for 
mostly clear skies with overnight lows near 50 north and the 
lower 50s south tonight...rebounding into the upper 70s or near 
80s by Saturday afternoon. 


Moisture will begin to increase on Sunday as the upper level 
ridge moves east...allowing south to southwest flow aloft. The Bay 
of Campeche low will lift north over the western Gulf of Mexico. At 
this time...it appears that the deepest moisture will remain 
offshore with easterly ll winds over the area. However...precipitable water values 
will increase to between 1.5 and 1.7 inches over southern portions of 
the area...with rain chances increasing from south to north Sunday. 
In addition...the easterly fetch will allow for water to pile up 
along the coast...with the potential for coastal flooding 
Sunday...especially at time of high tide. See the latest coastal 
flood statement for further details. 


Meanwhile...another feature to keep an eye on will be the 
development of Ida...which is prognosticated to strengthen back to a 
tropical storm by Saturday afternoon. Current forecasts take Ida into the 
eastern Gulf and eventually toward the western fla coast by midweek. The 
western Gulf low will gradually merge with Ida on Monday...producing 
a strong offshore flow as the system moves east of the area. At 
this time...the best chances for rain will be Monday into early 
Tuesday...with chances tapering off Tuesday afternoon from west to east 
as an upper trough crosses the region...pushing Ida further east 
and allowing a drier nwrly flow to develop aloft. 


Dry weather and near or slightly above seasonal temperatures are 
expected Wednesday through Friday as high pressure becomes 
re-established. 


Aviation...for 18z taf issuance... 
VFR conditions under generally clear skies should continue for the 
remainder of the afternoon and evening hours as high pressure 
prevails. Expecting another night of restricted visibilities as good 
radiational conditions are on tap yet again with clear skies and 
calm winds. At this time have elected to keep visibilities in the MVFR range 
with worst conditions (tempo 1sm br) at kbpt where low-level 
moisture is highest as southeasterly low-level flow has been in place 
longer. Once the light fog Burns off around middle-morning just a 
little cirrus and increasing southeasterly winds are expected. 


Marine... 
moderate east winds will strengthen this weekend as the pressure 
gradient tightens in response to a developing trough of low 
pressure over the western Gulf. The trough is expected to move 
east...potentially merging with forecast Tropical Storm Ida over 
the east central Gulf. The combination of Ida to the southeast and 
strong high pressure to the north will result in a significant 
offshore flow developing. A Small Craft Advisory will likely be 
needed beginning Sunday and continuing through middle week with winds 
of 20-25 knots and seas building to around 10 feet over the outer 
coastal waters. 


Hydrology... 
significant river flooding continues across the area. Most of the 
rainfall with the upcoming event is forecast to occur over the 
lower portions of the Neches...Sabine and Calcasieu rivers. At 
this time...this is expected to primarily delay the river 
recessions rather than cause an increase in flooding. 


&& 


Preliminary point temps/pops... 
klch 49 79 60 79 62 / 10 10 10 30 60 
kbpt 53 79 61 79 62 / 10 10 10 30 60 
kaex 46 78 55 78 57 / 10 10 10 20 40 
klft 50 79 61 79 62 / 10 10 10 30 60 


&& 


Lch watches/warnings/advisories... 
la...coastal Flood Watch through Sunday evening for the following 
zones: Cameron...Vermilion. 


Texas...coastal Flood Watch through Sunday evening for the following 
zones: Jefferson...Orange. 


GM...none. 
&& 


$$ 

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