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Area forecast discussion 
National Weather Service Lubbock Texas
521 am CST Friday Dec 26 2014

Aviation...
breezy southwest winds are expected this afternoon more so at kpvw and
klbb /14-16 kts/. A cold front was moving south across the Texas
Panhandle early this morning and will affect kcds this afternoon...and
a few hours later /early evening/ at klbb and kcds. Winds will
therefore veer to the north at or above 11 kts. MVFR cloud decks have also
developed along the front this morning...and could make run at
kcds later this morning. Have inserted a few MVFR deck for this
possibility. Tonight...there are hints of MVFR cloud deck
development particularly at kpvw and klbb. Not sure how thick the
clouds will get and will maintain a scattered MVFR deck for now. Will of
course amend as necessary.

&&

Previous discussion... /issued 321 am CST Friday Dec 26 2014/

Short term...
the focus in the short term period will be chances for a light
wintry mix this evening-tonight...courtesy of a cutoff low nearing
The Four-Corners region early this morning.

The aforementioned upper air disturbance is prognosticated to split into two
pieces...with the cutoff low ejecting NE to across the Central
Plains this evening and approach the Great Lakes region by late
tonight...whilst its southern periphery extends from across the County Warning Area to
near northwestern old Mexico by the end of the short term period. This
system will aid to push down a cold front currently impinging on the
far northern Texas Panhandle per 08z metars. Wind speeds behind the front
are not particularly strong /15-20 miles per hour/ and in fact is prognosticated to
subside a bit as it approaches the northern fringes of the County Warning Area this
afternoon...due to a relaxing pressure gradient. However...low clouds
accompanying the front could affect portions of the County Warning Area. As
previously mentioned...the front will move across the northern zones late
morning/early this afternoon...affect the central zones by late
afternoon/early evening and clear the County Warning Area at or above midnight. It is interesting
to note that the hrrr...NAM...GFS and European model (ecmwf) all display light quantitative precipitation forecast
signals across the far SW Texas Panhandle this afternoon. Slight middle-level
ascent coupled with moistening sounding profiles and frontogenetical
forcing are likely the reasons behind light precipitation being displayed.
With the atmosphere starting off relatively dry /pwats less than
0.30 inches/ it will take some time for the atmosphere to moisten
up. Thus...very light precipitation in the form of a rain and snow mix
across the SW Texas Panhandle will be favored versus more significant
amounts.

Large scale ascent will be at its peak from 27/00z-12z...as the
cutoff low brushes across the panhandles region and its southern
periphery nears the region during that time. As previously
mentioned...the atmosphere will need time to moisten up and is
possibly the reason for a few forecast solutions showing dismal
precipitation in both coverage and amounts. The favored areas will be
across the southern South Plains and rolling plains hence coinciding with
the best precipitable waters . Snow and a rain and snow mix will be the precipitation type
on The Caprock this evening...followed by all snow on The Caprock
overnight...versus liquid initially off The Caprock which will
transition over to a rain and snow mix overnight. Again...snowfall
accumulations are expected to be light.

Temperatures will be a bit tricky as it will be highly dependent on the
speed of the front. With the front expected to enter the northern South
Plains and northern rolling plains during the afternoon while slightly breezy
S-SW surface winds occurs elsewhere /ahead the front/...temperatures will range
form the lower 40s across the far SW Texas Panhandle to the middle 60s
across the Low Rolling Plains. Overnight lows will be chilly...ranging
from the teens across the SW Texas Panhandle to the lower 30s across
the Low Rolling Plains.

Long term...
focus this morning is on very cold air expected to settle into the
region Monday night. A long wave trough has settled over much of
North America...and upper flow will become even more broadly
cyclonic with time. That will allow cold air over the northwest
territories and north of Alaska to finally break southward. Will
continue previous forecast trends of undercutting MOS guidance and
trending much closer to raw model output for temperatures Tuesday through
Thursday. The approach of a closed low from the west late in the
week will result in incresed low to middle level warm advection which
could begin to lift temperatures toward Thursday...however with abundant
cloud cover expected will keep a narrow diurnal range through the
week. That closed low could bring some precipitation to the forecast
area as early as Thursday with slight chance probability of precipitation enough to cover
for now. Precipitation phase could become a problem if warmer solutions
end up winning out. For now will keep mention only as snow since
favoring colder column.

Closer to the near term...positively tilted shearing upper trough
should weaken enough by Saturday morning to see light precipitation
dissipate. Temperatures to be quite cool behind a cold front Saturday but
warm Sunday toward seasonal norms with breezy westerly low level
winds developing behind the aforementioned trough. Then will be
waiting for the cold air arrival...model timing beginning to home
in on Monday daytime hours likely resulting in a north-south high
temperature gradient. Finally...still cannot discount possibility of some
light precipitation Tuesday behind the front as low levels saturate and
some weak isentropic lift develops over the cold dome of air.

&&

Preliminary point temps/pops...
Friona 41 16 34 17 47 / 20 20 10 0 0
Tulia 47 20 36 19 49 / 10 20 10 0 0
Plainview 53 22 38 20 49 / 10 20 10 0 0
Levelland 57 23 39 22 50 / 10 20 10 0 0
Lubbock 59 23 40 22 50 / 10 20 10 0 0
Denver City 56 26 40 25 49 / 10 20 10 0 0
Brownfield 58 26 40 24 50 / 10 20 10 0 0
Childress 58 27 40 23 52 / 0 20 10 0 0
spur 64 27 41 25 51 / 0 20 10 0 0
Aspermont 66 32 42 27 51 / 0 20 10 0 0

&&

Lub watches/warnings/advisories...
none.
&&

$$

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