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Tireman4 wrote:Goodness. H. Gracious. I hate to curse on here. I know Porta said this was a family oriented show, but good gosh almighty. This Mountain Cedar is no joke. Two weeks and still struggling. Sigh. Sigh.
.PREV DISCUSSION... /ISSUED 335 AM CST Thu Jan 12 2017/
Another breezy and mild early morning on tap, with a stratus deck
expanding west to a Comanche-Fort Worth-Sherman line. Strong WSW
zonal flow aloft was occurring, while a very shallow arctic
airmass (per LAPS soundings north of the Red River) was sinking
readily south across the southern High Plains and western OK.
Meanwhile, our weekend system can be seen via water vapor imagery
digging southward over CA and toward Baja region of Mexico.
We are starting to see signs that despite the very shallow nature
of the arctic airmass to our NNW, that it`s properties are fairly
dense considering the falls into the lower 30s to mid 20s instantly
behind this cold front. Models, especially those of less resolution
really have a hard time handling such shallow and dense airmasses.
After collaboration with many neighboring offices, it was decided
to use a CONSHORT/HRRR or RAP/ADJMET blend on temperatures, dewpoint
temps, wind shifts, and sky cover. The shallow arctic front will
cross the Red River mid-late morning and continue to ooze readily
southward through the I-20 corridor this afternoon. This is all
occurring despite a lack of upper level support, as the airmass
is obviously very dense as seen by the 4mb/hour pressure rises
occurring across North-Central OK as of 3 am CST. I will show
early daytime highs across the northern tier of counties this
afternoon, with falling temperatures during the afternoon.
Otherwise, a subtle shortwave will induce a few showers and
possibly an isolated storm tonight. Nothing of too much
significance, but column moisture is well-above normal for early-
mid January. That said, rainfall amounts should be light during
this period.
Now it must be stated it`s not certain how much of the arctic
characteristics this shallow airmass will possess as it continues
in Western Central TX tonight into Friday. We did go with the
furthest south solution of the NAM model after collaboration with
neighbors, but have some blend of the HRRR and CONSHORT high
resolution data thrown in. As low rain/convective chances continue
through Friday and Friday night with our main upper low well to
the west, we are not anticipating winter precipitation just yet
with uncertainty on how cold this airmass will actually be across
our NW and Red River counties. Per collaboration, we`ll keep
temperatures across those areas above the freezing mark as of now,
but the thermal properties of this airmass will need to be
monitored and analyzed diligently the next 24 hours.
For now though, just chances for a cold rain, with an occasional
isolated rumble of thunder tonight through Saturday. I do not have
the cold front pushing south out of our Central TX counties right
now, so it`s possible convective showers could modify the front`s
properties due to it`s very shallow nature. There will be a wide
range in temperatures both for overnight lows and daytime highs
from today through Saturday. Highs will range from the lower 40s
NW to the lower 70s in the SE counties.
Come Saturday night into Sunday, the shallow cold airmass should
be modified enough and shoot back north as a warm front in
response to strong height falls approaching from the west with our
upper low tracking east over northern Mexico. Luckily, we should
be well within the warm sector as large-scale ascent arrives into
the area. As a kicker system continues deepening across the
Western U.S., the first upper low will readily lift northeast from
Mexico into KS/MO by Monday afternoon, generally dragging a
pacific cold front into our E/SE counties. With mid to upper
level energy remaining to the west within the main longwave
trough over the Rockies, it appears the Pacific front may hang up
somewhere across far E and SE TX. As such, have left low
convective chances lingering across our eastern counties Monday
night through Tuesday night. Low confidence here folks.
While the all parameters of moisture well above normal levels,
strong ascent with the approach of the upper low and associated
Pacific cold front, and wind shear, it`s the instability that
appears to be murky at this time. There will likely be a stout
elevated mixed layer to overcome by late Saturday into early
Sunday, but eventually it should moisten, lift, and give way to a
progressively linear band of showers and thunderstorms, some with
localized moderate to heavier rainfall. That said however,
multiple calculated storm totals indicate most will receive 1 to 2
inches, with possible isolated amounts to 3 inches across the
northeast counties. Though widespread flash flooding isn`t
expected, there may be a few areas that see some training with a
localized threat. In addition, runoff will be more efficient due
to the cold and dormant soils in place. The main stem Brazos and
Trinity River basins could definitely see rises occurring early
next week. A few strong to maybe a marginally severe storm or two
will be possible within the warm sector later Sunday into Monday.
However, think the overall general lack of instability should
keep convection behaved for the most part.
Drier and seasonably cool or cold weather should return for the
latter half of next week and have kept to a dry forecast after
Tuesday. Lastly, there are many uncertainties regarding the shallow
cold arctic air and how far south it track, along with actual thermal
properties the end of this week into Saturday. This could play a
role on precipitation type. Confidence is somewhat better with the
first strong system moving out late in the weekend into next week.
How much rain lingers back is still in question after Monday, as
is the flood threat. Best to keep tracking later forecasts and
graphics regarding the expected weather changes through the weekend
into early next week.
Active weather pattern to bring stormy conditions to SE TX this weekend into next week.
Temperatures likely to remain well above normal with records possible.
Upper level storm systems that have brought incredible snow and rainfall to CA this week will begin to dig southward into the SW US over the weekend. An arctic cold front currently extends from the TX panhandle to central OK and has continued to drive southward even under unfavorable upper level flow. Main questions going forward is when does the cold front arrive into SE TX along with higher rain chances and how much rainfall.
Global models keep the mean trough across the western US into early next week with SW upper level flow across the region and also keep the arctic boundary stalled across NC TX into OK. Reality is suggesting a different story as the arctic boundary is progressing southward steadily this morning under density considerations of the very cold air mass and the boundary is outrunning most is not all computer guidance. Based on trends expect this boundary to continue southward into TX today and possibly even approach our northern counties on Friday. After that it is hard to say with much certainty just how far south the boundary may move over the weekend.
The boundary position becomes important into the weekend as that is where the axis of rainfall will tend to focus as disturbances ride SW to NE along the front. Moisture levels will certainly be high enough to support some good rainfall rates and the slow moving or stalled nature of a front could allow totals to gradually pile up. This is something that will need to be watched over the next few days…needless to say forecast confidence is low.
Early Next Week:
A strong upper level system will eject across the state late Sunday into Monday which will help push the stalled boundary deeper into SE TX. Strong lift across an unseasonably moist air mass looks to promote widespread showers and thunderstorms some of which could become severe. Some of the guidance wants to then stall the front again over SE TX (maybe near the coast) Tuesday and Wednesday as yet another upper level system approaches from the west. This would result in a prolonged rainfall event over the area as moisture overruns the frontal slope with favorable jet stream positions aloft.
While moisture levels are certainly going to be high the uncertainty on where surface features will align is making for a very difficult rainfall forecast on amounts and location. Areas near the coast may see very little rainfall until Monday while inland areas could see rainfall from late Friday through next Wednesday depending on just how far south the front moves before stalling.
For now will go with widespread 1-2 inches, but it is likely these numbers will need to be pushed upward in the coming days.
As for temperatures…for locations south of the front spring will continue with near record highs each day in the upper 70’s to low 80’s. Lows will generally be in the mid to upper 60’s. As dewpoints rise tonight into tomorrow the chances for a prolonged dense sea fog event is looking more likely and this will continue through the weekend and into next week or until a front can move off the coast.
As for the Houston Marathon on Sunday morning….it looks warm and muggy with temperatures in the 60’s and 70’s and a 20% chance of rain.
TheProfessor wrote:I feel sorry for our NWS Mets up here, Here in Columbus we could get anything from nothing to .4" of freezing rain(well above warning criteria, which is .25"). I find it interesting that .25" of freezing rain is the only criteria that's the same for Ohio and North Texas, which goes with what someone told me that there really isn't a state that can handle an ice storm like some states can handle snow storms better. I've met a lot of the forecasters at the NWS in Wilmington, Ohio, they're really nice but they're probably pretty tense right now, especially since there are parts of their CWA who like me, might not get anything, but might get as much as .75" of ice.
Ntxw wrote:TheProfessor wrote:I feel sorry for our NWS Mets up here, Here in Columbus we could get anything from nothing to .4" of freezing rain(well above warning criteria, which is .25"). I find it interesting that .25" of freezing rain is the only criteria that's the same for Ohio and North Texas, which goes with what someone told me that there really isn't a state that can handle an ice storm like some states can handle snow storms better. I've met a lot of the forecasters at the NWS in Wilmington, Ohio, they're really nice but they're probably pretty tense right now, especially since there are parts of their CWA who like me, might not get anything, but might get as much as .75" of ice.
No one can really handle lots of freezing rain. Even Canadian cities can be crippled pretty bad. The weight that ice adds to the power lines and trees is hard to prevent
Golf7070 wrote:Ntxw, are you still thinking end of Jan / first week of Feb before things change again? I know I have heard mention about things changing in pacific enough to alter the pattern in 2-3 weeks. Is that true? I personally don't want another transient setup, but that's just my thought
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