Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 111136 CCA

Area Forecast Discussion...CORRECTED
National Weather Service Amarillo TX
636 AM CDT Tue May 11 2021


For the 12z TAFs:

Somewhat tricky TAF cycle as we fluctuate between categorical
flight rules. We should be mostly in IFR to even LIFR conditions
through most of this cycle as plenty of boundary layer saturation
is present. Wind speeds will generally be out of the east, but
will have a northerly component by tonight. Light precipitation is
expected to be on and off today, with better chances for
accumulating rainfall tonight for mainly KAMA.



.PREV DISCUSSION... /Issued 331 AM CDT Tue May 11 2021/

SHORT TERM (Today through Wednesday night)...

Focus for the short term will be the first 36 hours as this
covers the potential hazardous weather through Wednesday. This
includes the chance for thunderstorms and patchy fog. Light
rainfall can also be expected with well below normal temperatures;
however, we do not have any threats from potential frost/freeze.
The well below normal highs today could lead to some record
coldest high temperatures (see below for further details).

In the upper levels, we have mostly zonal flow aloft over the
Panhandles, but there are two notable features that may come into
play during the short term. The first of which is a shortwave
located over the Desert Southwest/northern Mexico ahead of the
main H5 low (second feature) over northern Utah. Mid level water
vapor imagery reveals this energy starting to develop showers
ahead of the shortwave across west Texas. We expect this shower
development to continue through the overnight hours and into
tomorrow eventually pushing into the Panhandles. For the most
part, we are lacking forcing and instability, so thunderstorms may
be hard to come by today. While some instability can be seen in
forecast soundings aloft, it may be difficult to actually tap into
this energy with the amount of CIN in place. In fact, the stable
layer within the boundary layer would suggest this would be rather
difficult, but there is around 500 J/kg of CAPE aloft. Better
forcing and instability will be south and east of the forecast
area. Additionally, we have a cold airmass in place over the
Panhandles with ongoing light rain/drizzle as of writing this, and
this looks like a good trend through the day as we expect a cold and
cloudy day with light rain to persist. Perhaps a few isolated
thunderstorms may occur, but severe weather looks pretty unlikely
today. Easterly upslope flow at the surface in addition to isentropic
lift should lead to light rainfall/drizzle all morning. We should
see a break this afternoon, but then the main H5 low kicks out over
the Central Plains, and we will have another shot at rainfall tonight
as the surface high spreads farther south and east along with the
colder air. We have 700mb theta-e advecting in over the cold dome of
air at the surface, and this may lead to better rainfall amounts
tonight into Wednesday morning, especially the southern TX Panhandle
where we have 700mb frontogenesis as well. Again, we are lacking
instability, so we may end up with mostly rain showers through
Wednesday morning.

Lastly, highs are going to be 20+ degrees below normal today which
could lead to some record cold high temperatures (see below), but
fortunately the cold air sinking in with the surface high doesn`t
indicate any frost or freeze potential. Some areas in the
northwest are going to be close though with upper 30s forecast for
a low tonight.

Record Lowest High Temperatures for May 11th:

Amarillo.........51 set in 1954 (Current forecast - 53)
Dalhart..........49 set in 1968 (Current forecast - 50)
Borger...........50 set in 1954 (Current forecast - 55)


LONG TERM...Thursday through Monday

A very active pattern shaping up late this week into the weekend
and early next week. Northwesterly flow aloft Thursday across the
Panhandles will allow for perturbations over the central Rockies
to track southeast Thursday night. Convection may develop Thursday
night across portions of the northern, central and eastern
Panhandles. Upper ridge builds in across the southern and central
Rockies Friday with a shortwave trough moving east out of the
central Rockies by late Friday. Convection possible Friday
afternoon across the northwest Panhandles and then spreading east
across the eastern half of the forecast area Friday evening.

Another upper trough to track east out of the central and
southern Rockies late Saturday which should allow for convection
across the Panhandles Saturday afternoon through Saturday night.
Still another upper trough will track south and east out of the
central Rockies and central Plains states Sunday into Sunday night
allowing for additional convection chances across the forecast
area. A closed upper low is forecast to track east out of southern
California Sunday and across the southwestern states and the Four
Corners region Sunday night into Monday morning. This closed
upper low will bring additional chances for convection early next

The cool surface ridge will finally dislodge and push off to the
east Thursday which will allow for the surface flow to transition
from upslope to downslope as winds become south and southwesterly.
Warmer conditions expected starting Thursday and continuing
through Sunday as surface low pressure develops to the lee of the
Rockies late this week into the weekend. The pressure gradient
will tighten up as the surface low pressure deepens and winds
increase and become breezy. Surface trough or dryline to track
south and east into the Panhandles Friday and Friday night before
retreating back to the west and north Saturday. Surface low over
the southern Rockies Sunday with associated trough or dryline to
push into the northern Panhandles Sunday afternoon and evening
followed by the passage of a cold front Sunday night. Surface
ridge to build down into the forecast area from the north and east
allowing for cooler and moist upslope surface flow once again
early next week.



.AMA Watches/Warnings/Advisories...


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