Area Forecast Discussion
Issued by NWS Amarillo, TX

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46

FXUS64 KAMA 051130 AAA

Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
530 AM CST Tue Dec 5 2017

For the 12Z TAFs, VFR conditions will prevail at the terminal
sites through 12Z Wednesday.



.PREV DISCUSSION... /Issued 354 AM CST Tue Dec 5 2017/

No major changes from previous forecast. Latest upper level
analysis places upper trough axis over far eastern Dakotas with
broad cyclonic flow over the northern plains stretching out over
the Great Lakes. Split flow aloft is evident over the southern
plains as an elongated positive tilt trough over southern CA/NV
maintains zonal flow over the southern CONUS with northerly flow
impinging in wake of the northern plains trough. Anticyclonic flow
is becoming more dominant now centered just off the west coast as
a high pressure ridge is amplifying there. At the surface, a cold
Canadian airmass continues to filter into the Panhandles behind
yesterdays cold front as a transient surface ridge approaches the
area. Temperatures are already at or below freezing as of 0900z
and will continue to fall into the 20s as north winds decrease to
around 5-10 knots this morning. Abundant mid and high level clouds
are also showing up on satellite and radar returns and may be the
one limiting factor preventing much colder temperatures this
morning. This pacific moisture is mostly confined above 800mb with
very dry air below 800mb. Thus, keeping mentionable pops out of
grids even though can`t rule out a flurry or two this morning
given weak lift in the 700-500mb region due to right entrance
region of a jet streak and some confluence around 700mb. Clouds
will begin to decrease for all but the far southern Texas
Panhandle this afternoon as temperatures only top out in the 40s.

For this evening and overnight, model guidance has been trending
towards a band of precipitation forming just south of the
Panhandles in response to some increased jet dynamics along the
zonal flow and some moisture convergence around 850-700mb. At this
time it looks like our counties will stay just north of the
precip band with good model to model consistency on location of
best forcing. However, a slight deviation northward with 500mb jet
streak and our southern Texas Panhandle counties could see what
would most likely be light snow given cold thermal profiles
mainly between 03z and 09z tonight. For now, keeping forecast dry,
but will need to monitor for possible updates if models/observations
start trending north.

The rest of the forecast will be dominated by the amplifying ridge
over the west coast and the long wave trough over the eastern
CONUS. The development of this omega block will put the southern
plain in meridional flow from Wednesday though Friday. Cold fronts
will advance through the Panhandles on each of those days keeping
temperatures 5-10 degrees below average with breezy north winds.
The west coast ridge is expected to weaken some and shift east
into the weekend which will help shift the colder air further east
and allow the Panhandles to begin a warming trend.



.AMA Watches/Warnings/Advisories...


$$ is the U.S. government's official web portal to all federal, state and local government web resources and services.