310 
fxus64 kmrx 210903 
afdmrx 


Area forecast discussion 
National Weather Service Morristown Tennessee 
400 am EST Sat Nov 21 2009 


Short term (today and tonight)...high pressure over the region will 
retreat northeast as a weak low pressure system moves slowly along 
the Gulf Coast. Will see high clouds around again today...then some 
light rain may make it into at least southern and southeastern zones 
by late tonight. Will carry chance probability of precipitation south and southeast...but 
will go dry north tonight. Mav temperatures generally look reasonable...so 
just a few tweaks. 


Long term (sunday through friday)...stayed closer to the European model (ecmwf) for 
the early portion of the forecast then tried to use a blend of 
European model (ecmwf)/GFS from middle week on. Tweaked forecast probability of precipitation back a bit in time 
and geographically especially northern and western sections for 
Sunday and Sunday night as Gulf Coast system still prognosticated to be 
rather weak and displaced south and east of the forecast area as low 
level ridging holds on across the northeastern quarter of the 
nation. Also slowed improvement somewhat on Monday as weak system 
slower to progress far enough away from the southern Appalachians 
than previous thinking. Per model suggestion slowed down arrival of 
middle week upper trough and associated cold front pulling probability of precipitation from 
daytime period Tuesday and placing slight chance for a shower 
Tuesday night. Went with a dry Wednesday as region awaits 
amplification of mean upper trough over the north central U.S. With a 
healthy bit of energy dropping into the base of the trough for 
Wednesday night through Thursday night. Used slight chance showers 
with this system for now as we await better model depiction 
concerning timing and strength. Air becomes cold enough for mention 
of snow showers Thursday night into Friday morning. 


&& 


Preliminary point temps/pops... 
Chattanooga Airport, Tennessee 62 43 55 45 58 / 0 50 
60 30 20 Knoxville McGhee Tyson Airport, Tennessee 60 41 55 43 57 
/ 0 20 60 40 20 Oak Ridge, Tennessee 61 40 
55 44 57 / 0 20 60 40 20 Tri Cities Airport, Tennessee 
59 34 54 41 55 / 0 10 50 50 30 


&& 


Mrx watches/warnings/advisories... 
NC...none. 
Tennessee...none. 
Virginia...none. 


&& 


$$