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fxus64 klix 070941 
afdlix 


Area forecast discussion 
National Weather Service New Orleans la 
341 am CST Sat Nov 7 2009 


Short term... 
Sat 00z lix sounding was one of the driest seen since likely last 
winter with a precipitable water of 0.22 inches. There was an 
extremely dry low layer and significantly dry middle into upper layer. A 
shift from nerly to more due east in column winds should help 
alleviate this somewhat today. Surface ridge to the east and upper high 
overhead will continue eastward today. Not too much in the way of 
clouds and no rain expected across the County Warning Area. Highs should be a couple 
degrees warmer than yesterday and dew point/S are expected to rise into middle 
50s to lower 60s by this evening. Basically the same story tonight. 
Increasing moisture should keep lows from dipping down into the 40s 
as they have been for the last few days. 


Long term... 
generally speaking...Haven/T made many significant changes to the 
previous forecast due to good model run to run consistency over the 
last few days. Mainly just slight shifts in location of highest probability of precipitation 
and an increase to the definite category for Monday as confidence 
has been increasing. Upper low that will be the main cause for 
upcoming unsettled weather is currently over Baja California California and 
quickly moving eastward. It is prognosticated to stay on this trajectory 
across the southern Continental U.S.. meanwhile...an upper trough will dig 
south across the north central US and send a cold front towards the 
County Warning Area. A weak area of low pressure in the Bay of Campeche will be 
shifting northeastward towards the la coast Sunday night. At the 
same time...it appears that Ida will be moving towards our coast as 
well and should be in a transitioning stage into an extra tropical 
feature as the two lows merge. Needless to say...there will be 
plenty of moisture on tap as the southern open upper trough moves 
through. Model soundings indicate precipitable waters  reaching 2 inches by Monday 
morning. Rain chances should start ramping up in the southwestern parishes 
late Sunday night and peak Monday. On Monday night...a shift to a 
more gradient pop arrangement from east to west with higher in 
coastal miss as the system tracks eastward. Rain will be tapering 
off significantly by Tuesday but could still have some residual 
showers on the backside. Wednesday through the rest of the week should be 
dry as high pressure quickly builds in. 


Meffer 
&& 


Aviation... 
some river fog appears to have developed along the red and 
Mississippi rivers where nearby ASOS observations are detecting 
intermittent IFR fog and ceilings scattered v broken 001. These affects should be 
localized and have amended to reflect this at kbtr. Otherwise...VFR 
conditions are expected through at least 08z then patchy MVFR to IFR 
visibility in br/fog due to river fog once again after 08z through about 14z 
Sunday. 


&& 


Marine... 
easterly gradient is established at moderate wind levels initially 
but anticipated to strengthen throughout the day and Monday. 
Tropical Storm Ida is forecast to move north into the east-central 
Gulf and will really sharpen the gradient for a period of gale 
conditions...particularly farther from shore. Will Post a gale watch 
on this package for the beyond 20nm waters with conditions 
commencing around 06z Monday and continuing through 18z Monday due 
to ida's closest approach...some 220 miles southeast of kmsy and 
about 140 nm south of the mouth of the river. Per coordination with 
surrounding coastal offices and National Hurricane Center...will not 
mention any tropical related probabilistic statements as consensus 
agreement that affects should be most attributable to gradient wind 
components and not the circulation of Ida. Strong winds are 
expected to continue in an offshore component once cold front moves 
through Tuesday...so Small Craft Advisory conditions may last for several days before 
improvements are noted. 


Regarding coastal flooding...confidence continues to remain high 
that coastal flooding of a moderate magnitude will result with some 
minor inundation possible today...increasing in height with each 
subsequent tide cycle Sunday through Tuesday. Coastal Flood Watch 
will be maintained status quo at this time. Coastal flood warnings 
may still be warranted at a later time but would like to see some 
onset of runup at some of the tidal gages before issuance. 
Currently...most gages are showing 0.5 to 0.8 foot anomalies above 
predicted astronomical tide traces. As easterly winds 
increase...tidal runup should become more evidenced later today or 
by tonight. 24/rr 


&& 


Preliminary point temps/pops... 
mcb 77 50 75 58 / 0 0 10 30 
btr 78 55 76 61 / 0 0 10 50 
msy 79 60 76 65 / 0 10 10 50 
gpt 76 53 75 61 / 0 0 10 30 


&& 


Lix watches/warnings/advisories... 
la...coastal Flood Watch until noon Tuesday for the following zones: 
Livingston...lower Jefferson...lower Lafourche...lower 
Plaquemines...lower St. Bernard...lower 
Terrebonne...Orleans...St. Charles...St. John The 
Baptist...St. Tammany...Tangipahoa...upper Jefferson...and 
upper St. Bernard. 


GM...Small Craft Advisory until 6 PM Tuesday for the following zones: 
coastal waters from Pascagoula MS to the Southwest Pass of 
the Mississippi River out 20 nm...and coastal waters from 
the Southwest Pass of the Mississippi River to lower 
Atchafalaya River la out 20 nm. 


Small Craft Advisory until midnight Monday for the following 
zones: coastal waters from Pascagoula MS to the Southwest 
Pass of the Mississippi River from 20 to 60 nm...and 
coastal waters from the Southwest Pass of the Mississippi 
River to lower Atchafalaya River la from 20 to 60 nm. 


Small Craft Advisory from noon Monday to 6 PM Tuesday for the 
following zones: coastal waters from Pascagoula MS to the 
Southwest Pass of the Mississippi River from 20 to 60 
nm...and coastal waters from the Southwest Pass of the 
Mississippi River to lower Atchafalaya River la from 20 to 
60 nm. 


MS...coastal Flood Watch until noon Tuesday for the following zones: 
Hancock...Harrison...and Jackson. 


GM...Small Craft Advisory until 6 PM Tuesday for the following zones: 
coastal waters from Pascagoula MS to the Southwest Pass of 
the Mississippi River out 20 nm...and coastal waters from 
the Southwest Pass of the Mississippi River to lower 
Atchafalaya River la out 20 nm. 


Small Craft Advisory until midnight Monday for the following 
zones: coastal waters from Pascagoula MS to the Southwest 
Pass of the Mississippi River from 20 to 60 nm...and 
coastal waters from the Southwest Pass of the Mississippi 
River to lower Atchafalaya River la from 20 to 60 nm. 


Small Craft Advisory from noon Monday to 6 PM Tuesday for the 
following zones: coastal waters from Pascagoula MS to the 
Southwest Pass of the Mississippi River from 20 to 60 
nm...and coastal waters from the Southwest Pass of the 
Mississippi River to lower Atchafalaya River la from 20 to 
60 nm. 


&& 


$$ 

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