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Area forecast discussion 
National Weather Service Albuquerque nm
1111 PM MST Friday Feb 27 2015

Aviation...
06z taf cycle
widespread MVFR to IFR ceilings/visibilities in snow and fog across forecast area rest
of night and into at least Sat morning...although less snow and
higher ceilings and visibility mainly south of a line from roughly Ruidoso to
Fence Lake. Mts continuously obscured through at least Sat morning.
Generally lowest ceilings likely at saf...lvs and fmn. Snow expected
to diminish somewhat or become more spotty between midnight and
dawn except may increase a bit north of a roughly saf to gup line.
Most or all of the SW half of the forecast area should improve to VFR
conditions by late morning or early afternoon with temperatures rising above
freezing. Some Montana obscurations may continue even into the afternoon.
These general conditions likely into Sat evening.

43

&&

Previous discussion...332 PM MST Friday Feb 27 2015...
synopsis...

An unsettled weather pattern continues over northern and central
New Mexico as a series of storm systems push over the region. As
one upper level disturbance departed the state to the east this
morning...another one is currently arriving from the west.
Additional snow accumulations are expected this evening and
overnight...primarily in northwestern to central and north central
parts of New Mexico. Into Saturday and Sunday...another potent
disturbance will dive into California before slowly spreading over
New Mexico. A prolonged period of high elevation snow is expected
over north central to northwestern New Mexico
Saturday...Sunday...and into Monday and Tuesday. The highest snow
totals will be found in the San Juan or Tusas Mountains near the
Colorado border where an additional one to two feet of snow could
accumulate...primarily in the higher elevations above eight
thousand feet. Rain will fall in lower elevations during this
weekend to early next week period.

&&

Discussion...
the middle of a barrage of upper level disturbances. Not much of a
respite or lull in the precipitation was observed this morning
before the next upstream system started spreading more batches of
snow into wetsern nm. This latter disturbance is a bit more subtle
looking on water vapor imagery compared to its
predecessor...however jet dynamics are underway and strengthening
with lots of divergence aloft being depicted by forecast models.
This seems to be quickly coming to fruition given light snow that
has already ensued and started again in central to western zones.
Forecast models keep this divergence aloft pegged over the
northwestern quadrant of nm tonight...and quantitative precipitation forecast is generously
painted beneath. Hrrr model is also quite generous with this trend
with a few mesoscale bands of snow being depicted. Thus...felt
prudent to spatially and temporally extend advisories/warning
westward and longer respectively. These amendments were made at
noon and will hold for now.

Into Saturday the divergence slowly decreases in intensity over nm
and the flow aloft begins backing more southwesterly as a low
takes shape and dives into California. This should begin a reduction in
the coverage of precipitation in some lower elevation
areas...reduction being relative...while orographics become the
more dominant forcing mechanism for the higher terrain. Elevations
below 7000 feet would also observe a quick warming trend as warm
air advection begins in the southwesterly flow. The forecast
models may be a bit too high with maximum temperature guidance on this
though...as the cloud cover may be slow to erode...stunting the
warming more than what is advertised by models. Have built in a
quick changeover to rain in these lower elevations by late morning
and into the afternoon...but this could be a bit premature and
will need to be closely monitored. Precipitation could also begin
to take on a showery or convective nature to it as models have
lifted indices of 0 to -1c prognosticated over some north central to
northwestern zones Saturday afternoon. This would only add to snow
rates in the higher terrain. The winter highlights/statements in
the northwestern zones drop off Saturday morning...but may need to
be extended for aforementioned reasonings.

The precipitation really focuses toward the northwestern third of
the forecast area into Saturday night and Sunday with flow
continuing to back slightly more while speeds aloft increase. This
will keep steady orographic forcing over the north central to
northwestern mountains with some pronounced precipitation shadows
downwind or northeast of chuskas and other topographical barriers.
The southwesterly flow aloft and rising pressure heights will also
keep the warmer air advecting this way...and Saturday night's low
temperatures will be 10 to 15 degrees warmer than tonight's
readings while sunday's highs rise another 5 to 15 degrees above
saturday's highs. This warming trend will shift snowfall
accumulations upward to 7500 to 8500 feet Sunday afternoon. While
this will limit the spatial area of snowfall accumulations...the
peaks above this threshold will still see remarkable snow
amounts...likely one to three feet on many peaks above 8500 feet
and closer to four feet near the Colorado/nm border above 10000 feet.
Runoff and snow melt at lower elevations will also need to be
monitored closely on Sunday...perhaps creating hydrology issues.

And the threat for accumulation still won't end through Monday as
the upper low rounds Southern California and drives a Pacific front closer
to nm...eventually crossing into our forecast area Monday night.
This frontogenetical forcing in itself will also induce a healthy
slug of precipitation...possibly enhanced by a subtropical
moisture tap. Then a kicker short wave trough will dig on the back
side of this before turning into old Mexico Tuesday and early
Wednesday. Finally the caboose in the train of storm spills
southward in strong meridional flow on Wednesday...unlocking the
door to some very cold Continental polar air. Once this system
passes...a welcome drier pattern should follow into Thursday of
next week.

52

&&

Fire weather...

An active weather pattern will persist through the middle of next
week. Moist westerly flow will continue over northern and central
New Mexico tonight and Saturday...allowing west facing higher
terrain locations...especially from the west central to the north
central...to continue picking up snow. The winds aloft transition to
southwest Sunday into Monday as an upper low/trough dig into socal
and Arizona. Temperatures will warm in advance of the low...allowing
snow levels to gradually rise from what they are this afternoon.

Some cooler air may enter the eastern plains Sunday...both European model (ecmwf) and
GFS agree...but looks like it merely retards warming in the plains
for another day rather than brings another surge of much colder air.
A split flow pattern dominates early to middle next week...permitting a
much colder and drier air mass to surge into the eastern plains
Tuesday night/Wednesday. This looks to be the last gasp for the
active weather at least for the rest of next week.

Through early next week...heavy snow accumulations are likely for
the northern mountains. Although snow levels are forecast to rise
Sunday into Monday...some of the higher northern/western terrain
will continue to receive snow...and snow levels overall fall again
Tuesday as the upper low/trough move overhead and to our south.

High temperatures through the middle of next week will remain below
average. Vent rates will be poor in the east Saturday and Sunday but
good to excellent over most of the west central and southwest due to
increasing winds and mixing heights. Vent rates overall next Monday
and Tuesday will be excellent then worsen somewhat Wednesday.
Excellent relative humidity recoveries expected through the period although min relative humidity
values trend much lower Wednesday into Thursday.

&&

Abq watches/warnings/advisories...
Winter Storm Warning until 8 am MST Saturday for the following
zones...nmz502>504-516-518-519-521.

Winter Weather Advisory until 8 am MST Saturday for the following
zones...nmz501-505>507-517.

Winter Storm Warning until 4 PM MST Sunday for the following
zones...nmz510>515-527.

&&

$$

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