094 
fxus64 kjan 071608 aaa 
afdjan 


Area forecast discussion...updated 
National Weather Service Jackson MS 
1008 am CST Sat Nov 7 2009 


Update...current forecast is on track and the only adjacent that were 
needed were to tweak hourly temperatures/surface dewpoints to match current trends. 
Quiet conditions will remain through sun evening with an increase in 
some high clouds later tonight and especially on sun. /Cme/ 


&& 


Aviation...VFR conditions will prevail at all taf sites over the 
next 24 hours. Look for sustained south to southeasterly winds 
between 5-10 knots at all sites today...with a few gusts around 15 
knots possible across the Delta Region...kglh and kgwo. These winds 
will quickly diminish at sunset with calm to light winds expected 
through the overnight hours...with some patchy ground fog possible 
around day break at most sites...namely kmei and khbg. /19/ 


&& 


Previous discussion... /issued 405 am CST Sat Nov 7 2009/ 


Discussion... 


Heavy rainfall is still possible Monday and Monday night... 
especially southeast of the Natchez trace...as moisture associated 
with Tropical Storm Ida surges north. 


Today through Sunday night... 


High pressure is still in place across the southeastern states with 
a continuation of clear skies and warm daytime temperatures expected today. 
Mav guidance looked good for this afternoon but did bump highs a 
degree or two based on weak warm air advection expected on the back 
side of high pressure to our east. Mostly clear skies can be 
expected again tonight with upper level cloud cover increasing over 
southern zones as the upper high shifts east. Mav lows for Sun 
morning looked good although did lower a couple spots a degree or 
two based on ensemble guidance. Sunday will be another nice day with 
cloud cover continuing to increase as upper level flow gradually 
shifts to the southwest. Highs will stay above normal...generally 
middle 70s. Mav guidance was on the low end of the guidance envelope 
here and did bump afternoon highs a degree or two at most sites. 
Middle/upper level flow will shift south on Sunday night ahead of an 
approaching southern stream shortwave crossing the Rio Grande 
Valley...which will really open The Gate for Gulf moisture to 
increase over the arklamiss. GFS/European model (ecmwf) in good agreement showing 
rain beginning to overtake southern areas after midnight Monday 
morning as the southern stream shortwave interacts with the deep moisture 
moving into the arklamiss ahead of Tropical Storm Ida. The increased 
cloud cover and rain will keep overnight lows much warmer Monday. 
Mav guidance definitely looked low here and bumped lows into the middle 
50s north/upper 50s south in line with ensemble guidance. /Bk/ 


Monday and Monday night... 


All model guidance is in general agreement that the southern stream 
shortwave trough crossing the Southern Plains will approach the 
lower MS valley region about the same time that Tropical Storm Ida 
is moving into the central Gulf of Mexico. The shortwave trough will 
sweep deeper moisture associated with "ida" mainly to the east of the 
forecast area...but there will be enough moisture and lift to bring 
heavy rainfall to the areas southeast of the Natchez trace as has 
been indicated in previous forecasts. The official NHC forecast 
track keeps the center of Ida southeast of the forecast area before 
it loses tropical characteristics. 


The wetter European model (ecmwf) brings the center of "ida" farther north and 
continues to be the most aggressive in bringing deep moisture and 
heavy rainfall to much of the forecast area...while the GFS/gefs 
still keep heavier rain over southeast portions of the area...which fits 
better with the official NHC forecast track of Ida. In the forecast 
grids have raised guidance probability of precipitation...especially southeast half of the area 
for Monday/Monday night given increasing confidence in this upcoming 
rainfall event. Very weak middle level lapse rates/instability will 
keep rainfall from being overly heavy...but a long duration of 
moderate rainfall will allow totals to top the two inch mark... 
especially in areas along the I-59 corridor where flash flood 
guidance values happen to be highest (well above two in/hr). 


Tuesday through Friday... 


Model guidance is in good agreement that a progressive pattern will 
allow the South Atlantic coast ridge to break down quickly Tuesday 
with our shortwave trough and associated rainfall zipping by to the east. 
A building ridge over the arklamiss will bring dry weather for the 
middle to late week with temperatures a little above climatic average. 
There are indications...especially in the latest European model (ecmwf)...that rain 
chances will increase again by next weekend as southwest flow 
redevelops over the area ahead of an approaching trough. Have gone 
with slight chance probability of precipitation for now in the forecast. /Ec/ 


Aviation...VFR conds generally expeceted through the period as high pressure 
dominates the region. Winds will remain light and srly this morning 
with srly winds increasing this afternoon. A few gusts to 15kts may be 
possible in the Delta 18-23z. Light Erly winds expeceted overnight. Low level 
moisture will be on the increase today...and may allow some MVFR/IFR 
fog/ceilings to develop in southern areas tomorrow morning. /Bk/ 


&& 


Preliminary point temps/pops... 
Jackson 77 47 75 57 / 0 0 0 25 
Meridian 76 40 74 56 / 0 0 0 20 
Vicksburg 77 49 76 57 / 0 0 0 24 
Hattiesburg 77 46 76 57 / 0 0 2 31 
Natchez 77 53 75 59 / 0 0 0 35 
Greenville 74 47 75 54 / 0 0 0 13 
Greenwood 74 46 76 55 / 0 0 0 13 


&& 


Jan watches/warnings/advisories... 
MS...none. 
La...none. 
Arkansas...none. 
&& 


$$ 


Jan