Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Albuquerque nm
616 am MDT Tuesday Sep 1 2015
12z taf cycle
similar storm coverage...steering flow and aviation impacts
compared to yesterday. Think gup/aeg/abq/saf/lvs have the highest
likelihood of ts impacts. Indicated thunderstorms in the vicinity accordingly. Outflow
wind gusts between 30-40 knots also possible. Brief intrusions into
MVFR category due to heavier cells. Most of the development should
die down by 06z.
Previous discussion...344 am MDT Tuesday Sep 1 2015...
shower and thunderstorm chances should continue to favor central
and western areas through Thursday as monsoon moisture streams
northward and northeastward between a ridge of high pressure over
western Texas and a trough of low pressure on the West Coast.
Precipitation should become more widespread Friday and Saturday
as a low pressure system tracks across the Great Basin and draws
enhanced subtropical northward over New Mexico. A downtick in
precipitation coverage will be possible Sunday...especially across
the north...as somewhat drier air arrives from the west. High
temperatures are expected to remain near normal in the west and
above normal in the east through Wednesday. Readings will fall
with the arrival of better moisture starting in the west on
Thursday...then also across the east on Friday.
models are in pretty good agreement in the upper level pattern
until Friday night...when they begin to diverge on the placement
of the upper low crossing the northern Great Basin and the high
pressure center over Texas or OK. Compared to last nights runs...a
deep tap of subtropical moisture looks to arrive about 24 hours
faster in the latest runs...now arriving Friday rather than
Saturday. Its not clear in the latest runs how much of this
moisture may be associated with a potential tropical storm off
mexicos West Coast. The GFS ejects the Great Basin upper low more
quickly eastward across the northern rockies on Sunday than the
European model (ecmwf)...but the GFS follows it up with a second upper low on the north
California coast that the European model (ecmwf) does not show. This decreases confidence
somewhat on the Prospect of drier air moving in from the west on
Sunday. If low pressure lingers or redevelops over the Great
Basin...the subtropical moisture tap over nm may be able to
persist at decent strength.
not a lot of big changes made to the gridded
forecast. Did hedge surface dewpoints a little higher than model
guidance late week into the weekend. Also noticed that models were
going a little higher for surface dewpoints in the near term compared to
the past few days. This trend jives with what we have been observing
and based on the main monsoonal moisture plume location. This means
slightly higher humidity levels. Also increased surface wind flow across
the eastern plains...just a smidge above guidance. It appears that
the peak wind for the near term would be found during Thursday.
Similar results Friday/Saturday. Ventilation has also trended up
during the middle term period...Friday/Saturday readings look much
higher compared to yesterday morning forecast. Mixing heights lower
due to the influx of moisture but transport wind speeds have been
increased by the GFS model. This jives with the overall pattern with
a longwave trough to the west and the upper high to the east.
As far as the near term...a diffuse monsoonal moisture plume will
remain over the forecast area. Diffuse meaning...it could be more
moist for this time of year but not bad. The moisture plus near to
above average mixing heights will create isolated to scattered
thunderstorms with some numerous storms favoring the mountains at times.
It does appear that storm coverage would decline somewhat Wednesday/Thursday or
better yet...the footprint of wetting rain would decrease slightly.
Thursday is a bit more of a wildcard based on comparing all the
different models. Could be a little more coverage than originally
thought. Friday into the weekend still looks solid for an uptick in
atmospheric moisture thus storm coverage and wetting rain
footprints. During this time...the Pacific trough would draw closer
to the state while the upper high slides to the east. Transport
winds would increase and draw additional moisture from the Baja California
region...Aka Tropical Storm Kevin as well as off the Mexican madre
Confidence is pretty high for the influx of moisture although not
sure how much and for how long. The long range models seem to be
waffling around a bit on the return to some drier conditions. Based
on the European model (ecmwf)/GFS/Canadian models...eastern areas should see the
least amount of rainfall during the Friday/weekend into early next
week period. It should also be pointed out that the GFS remains a
little more of the outlier compared to the operational
European model (ecmwf)/Canadian which tend to provide a quicker drying trend. Still
like the GFS in this scenario and based on the time of year however.
The other wildcard feature is the back door cold front which the GFS
has become weaker during the past few model runs for the Sunday
night/early next week period. That is a bit concerning and doesnt
help the GFS cause. Will continue to monitor. Model uncertainty in
the extended period is to be expected this time of year as we
transition from a Summer to fall type pattern. These transitions
become more complicated due to tropical features.