Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Albuquerque nm
1150 PM MDT Friday Oct 31 2014
06z taf cycle
focus for -shra/thunderstorms and rain is currently shifting quickly NE over central
nm and that will continue through the overnight. Ceilings and visibilities will
remain VFR except for beneath heavier cores. Montana obscurations are
likely along the central Montana chain. Several profiles indicate MVFR
ceilings between 020 and 030 at ksaf by early morning which is much lower
than previously prognosticated. Models are also spreading better moisture
and dynamics east onto the plains overnight so increased coverage
of rain showers and lower ceilings into klvs and krow late tonight. Winds will
be the predominant concern Saturday with stiff southerly breezes in
place. A few -tsra still cannot be ruled out near the high terrain.
Previous discussion...1006 PM MDT Friday Oct 31 2014...
made some relatively minor changes in probability of precipitation...down the most across
the northwest mountains and Highlands...down a bit mainly west of Divide and
up a bit middle Rio Grande Valley NE to the general vicinity of sangre
Delaware cristos. Minor adjustments to 1st period minimum temperatures...mainly
higher...portions of roughly the northwest third. Minor cloud cover
adjustments as well.
Previous discussion...321 PM MDT Friday Oct 31 2014...
unsettled weather will impact northern and central New Mexico
through the weekend and into the earlier portion of next week. A
vigorous Pacific trough will be the culprit for the changing
weather. Wind speeds will increase ahead of the trough and provide
breezy to windy conditions during the weekend. Showers and
thunderstorms will initially start out on the drier side but trend
wetter as the weekend progresses. Sunday looks to be the favored
day for precipitation. Temperatures will eventually cool from west
too east later Sunday into Monday as the main portion of the trough
and corresponding cold front sweep over the area. This is when snow
levels will gradually lower. Expect some higher mountain
accumulations later Sunday into Monday.
current visible satellite imagery showing some convective/bubbling
cumulus over the western quarter of the forecast area. Models seem
to be in agreement with the best lift dynamics and corresponding
upslope moisture development over the northwest third tonight.
Increased probability of precipitation to reflect this tendency. Not a lot of precipitation
but should wet the ground. Higher surface dewpoints are poised to
infiltrate western/central areas from the south based on the
latest analysis charts. Especially during the overnight once
significant mixing ceases. Looking at gustier conditions with
passing showers rest of today due to high dcape values and
marginally low relative humidity values near the surface along and east of the
Arizona state line. Temperatures should warm overall tonight
thanks to increasing winds aloft...higher dewpoints and variable
Models are consistent in showing the best chance of precipitation
across the northwest third Saturday morning before lessening
precipitation chances during the afternoon. This is due to the trend
and movement of the first wave passage.
Decided to increase probability of precipitation for Sunday. Models have jumped around a
little bit in terms of highest quantitative precipitation forecast/pop areas past few runs.
However...decided that confidence was increasing to put out some
likely probability of precipitation for Sunday/Sunday night. It appears that two bands of
precipitation would develop over portions of the forecast area.
One band associated with the main trough dynamics would favor the
northwest third to half. Another band associated with a rich
subtropical moisture fetch would favor south central and
southeast areas. The 12z GFS has backed off on its quantitative precipitation forecast for this
period but decided that the more aggressive NAM looks to be a
little more reasonable based tpw satellite imagery over the Baja California.
Think the NAM has a better handle on the subtropical moisture
advection ahead of the Pacific trough. So trended quantitative precipitation forecast/probability of precipitation toward
the NAM but not all the way. Snow levels would gradually lower
later Sunday into Sunday night based on 0 degree c isotherm
forecast at 10000 feet mean sea level. Looking at the possibility of 3 to 6
inches above 8500 feet across the northern mountains so mainly high
country impacts. Hunters should be aware of this.
Models consistent with dragging the main Pacific trough over the state
on Monday/Monday night. Temperatures would cool considerably.
Looking at another round of widespread freezing Monday night.
Unsure wildcard would be residual cloud cover/low level higher dewpoints
across east central/southeast areas so unsure about freezing temperatures
there. Drier air would decrease precipitation chances and amounts during
this period. Models differ slightly on the exit of the subtropical
fetch across the southeast during Monday.
European model (ecmwf) remains the outlier in terms of breaking off a piece of the
Pacific trough Tuesday through Thursday and impacting the state.
GFS/dgex remain aggressive with the next drier and warmer ridge.
Canadian model hints at the European model (ecmwf) solution but breaks off the
piece of energy further west than the European model (ecmwf). Still way to early to
say which solution group will win out. Thus low confidence for
Tuesday and beyond.
forecast models have lacked continuity over the past several
runs...and some members continue to hold differing solutions
regarding the medium range.
Upper level ridge has quickly begun to break down as a Pacific
trough makes landfall on the West Coast. Southwesterly breezes aloft
will continue to increase into the weekend as disturbances
associated with the greater trough approach. Some middle level moisture
will continue to be transported toward nm while a weak tap into some
better subtropical moisture also becomes drawn into parts of the
state...although the latter tap should be mostly south and east of
the fire weather forecast area. Light to moderate south southwest
breezes late this afternoon will back at times...becoming
southeasterly in some valleys and central upslope areas. Better
boundary layer to middle level moisture will also ignite a few
high-based showers and storms in western nm that will produce very
little if any rainfall but some erratic downburst winds. These may
survive into central areas tonight...but the north central to
northwestern high terrain zones appear to be the most favorable for
receiving any virga or showers overnight.
Into Saturday the south southwest flow aloft will be quite strong
with winds at 10kft showing speeds of 25 to 40 miles per hour...but variable
cloudiness and middle level inversions could hamper mixing.
Also...there will not be a favorable Lee side surface cyclone...and
this will keep the surface gradient relatively weak. Thus wind
speeds at surface/20ft are not expected to meet their full
potential. So the Saturday forecast has been left with light to
moderate breezes with some locally windy spots in the higher terrain
where easier mixing can be attained. This will keep ventilation
elevated in most areas. Increasing dewpoints will continue to take a
roundabout path into nm...leading to much higher minimum humidity in
the afternoon. A few showers and storms will be possible as
well...mostly in the northern mountains.
The southwesterly flow aloft will increase a bit more into Sunday as
the Pacific trough breaks into two distinct pieces of energy...the
southernmost trough working eastward over Arizona. The winds at 10kft
approach 45 to 50 miles per hour briefly around noon Sunday...and a weak Lee
side surface low will help strengthen winds at surface/20ft level.
The strongest speeds are expected in the northeast Highlands near
Las Vegas/Roy/Raton. Better coverage of wetting rain with showers
and a few thunderstorms is expected Sunday due to better lift from
the approaching trough.
The remnants of the aforementioned Arizona trough will rapidly lift
northeastward across nm on Monday with precipitation also shifting
eastward along with the speed maximum aloft. Breezy conditions have
been left in the Monday forecast with speeds tapering off from west
to east throughout the day. The colder air will then arrive Monday
night into Tuesday morning with some freezing temperatures likely
invading some spots that have not yet froze this season.
Forecast confidence drops off from this point on...as models
continue to be at odds on evolution of additional pressure falls
upstream to the west. The European model continues to create a Deep
Cut-off low pressure system that spins west southwest of
nm...gaining subtropical moisture before tracking up into the state
and releasing copious precipitation. This seems to be an outlier and
a least likely scenario...but it has advertised this for
back-to-back model runs now.