Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Albuquerque nm
1029 am MST Monday Dec 9 2013
18z taf cycle
VFR conditions to persist through the taf period with clearing
this afternoon and evening. Gusty northwest winds to diminish rapidly
this evening...except at ksaf where northerly drainage winds will
tick up again early Tuesday morning.
Previous discussion...429 am MST Monday Dec 9 2013...
scaled back the coverage of the Winter Weather Advisory spatially
and temporally because the upper level trough is coming in drier
and a bit farther north than previously expected. Satellite
imagery and model data suggest much of the moisture with this
system has already ejected to the northeast or will do so by early
afternoon. We essentially kept the advisory in effect for east
central and plains locations that may accumulate additional snow.
This precipitation should come mainly in the morning and right around
rush hour...potentially making travel hazardous. Snow reports
around 1 inch and persistent echoes on radar suggest the Santa Fe
metropolitan area may have the most hazardous commute this morning...so
we are keeping the advisory in effect there too. Precipitation
should end quickly this afternoon as the base of the upper level
trough shifts east of the forecast area leaving very cold
temperatures in its wake. Highs today should range from around 13
degrees below normal in the southwest to as much as 31 degrees
below normal across northeast parts of the forecast area.
Northwest wind gusts today will reach 20 to 30 miles per hour from around
Clines Corners northwestward to The Four Corners...resulting in
very cold wind chills varying from the single digits above zero to
near 30 degrees below zero with the coldest readings in the northwest
mountains. Lows tonight will also be quite cold with readings in
the double digits below zero in parts of the northern and western
mountains and Estancia valley...and from near zero to the teens
above zero elsewhere.
Look for temperatures to warm a few to 20 degrees above todays
readings on Tuesday as the cold upper level trough distances
itself from the forecast area and surface winds begin to shift out
of the southwest. Although the weather will remain dry through
middle week under northwest flow aloft...temperatures should fall again as
much as 9 degrees across the east on Wednesday due to a back door
cold front that will sag into the plains Tuesday night.
Precipitation chances increase again Thursday and may linger into
Friday as an upper level low pressure system weakens into an open
wave while ejecting eastward across nm from the Baja California peninsula.
The European model (ecmwf) shows a better moisture tap off the eastern Pacific than
the GFS does with this system. However...models due generally
agree that western...southern and central areas will be favored
for rain and snow showers. For the first time in well over a
week...temperatures may reach within 5 degrees either side of
normal on Friday as this somewhat warmer weather system crosses.
Look for temperatures to fall again on Saturday as another upper
level trough and surface cold front dive southeastward and south
across nm quickly on the heels of the Baja California system. Models dont
currently depict much quantitative precipitation forecast with this system...but the northern and
western mountains could wring out a few showers.
final disturbance will cross over the forecast area today. The bulk
of the precipitation will have ended by middle morning but residual
light snow showers could continue into the afternoon. This is the
light/high snow ratio variety so not a lot of liquid water. Wind
will be breezy at times middle day through the afternoon across western
and central areas. Due to the trough passage mixing heights actually
look pretty high for this time of year over western and central
areas but will be quite low across the eastern plains. Since
transport winds will be pretty strong across the western two thirds
ventilation will be pretty good there.
A strong middle level dry slot/intrusion will flow in from the west
Monday night and remain entrenched over the area through at least
Wednesday. Went a little lower than model guidance on
dewpoints...especially overnight despite some anticipated melting
snow. Snow melt or sublimation will prove problematic in
areas...especially as the surface heats up some. Despite some
warming high temperatures will range between 10 to 20 degrees below
normal east and 5 to 20 degrees below normal west.
Bottomline...cooler conditions. Tuesday appears to be the lower
humidity day and coincides with the very strong dry slot overhead.
The dry slot will weaken some on Wednesday and allow humidity values
to climb. The inversion will be quite strong Tuesday and Wednesday
with low mixing heights. Transport winds will also generally be on
the low side with dominant high pressure most of the period. Either
way...ventilation rates will drop dramatically Tuesday and remain
pretty low into Wednesday.
A piece of Pacific trough energy is forecasted to break off from the
parent trough the next couple of days and could be a
player...weatherwise...for New Mexico Thursday/Friday. All of the
models show the Baja California low eventually working its way up over Arizona
on Thursday. This means some sort of moisture advection should occur
ahead of it and start to impact southern portions of the forecast
area on Thursday. The low should eventually track over the area
Thursday night and Friday. The GFS isnt showing much in the way of
precipitation. The European model (ecmwf) shows a little bit more coverage but still
not real heavy on liquid water amounts. Either way...expect cloud
cover to increase with temperatures trending up...especially ahead
of the low passage. Mixing heights will most likely increase across
the west and perhaps some higher north Central Mountain terrain Thursday
afternoon and spread eastward on Friday. Transport winds should also
increase during this period...especially favoring the higher ridges
and eastern plains. Ventilation rates will respond by initially
increasing over the west and perhaps sangre Delaware cristos Thursday and
then the improvement should transition across the entire area on
Friday. This will be a tricky forecast due to the closed low nature
to the system. Confidence is moderate at this time.
A drier northwest flow is expected over the weekend.
Winter Weather Advisory until 4 PM MST this afternoon for the