Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/21/18
Area Forecast Discussion...UPDATED
National Weather Service Brownsville TX
705 PM CST Tue Feb 20 2018
.DISCUSSION...Recent radar trends have indicated some leading
stratiform from convection upstream moving into Starr and Zapata
Counties this evening. In response to this, increased POPs this
evening to better reflect the evolving situation.
The thunderstorm potential looks conditional at the moment. SBCAPE
(~2000 j/kg) and low level backed winds show some potential. The
primary limiting factor is weak low level shear. HRRR has been
bullish with convection across the west, however, as a capping
inversion increases overnight think shear will not be the only
limiting factor. If storms can maintain and move a little east
into less inhibition and away from stratiform contaminated air,
can`t rule out a strong storm or two...again very conditional.
.PREV DISCUSSION... /issued 535 PM CST Tue Feb 20 2018/
..00z Aviation Update...
DISCUSSION...Updated for latest aviation discussion below.
AVIATION...The primary story this TAF cycle will be continued
MVFR/IFR ceilings and brisk southerly winds. Overnight, cloud
bases should remain steady or lower somewhat, perhaps as low as
IFR at times for HRL. Can`t rule out some very light shower
activity for HRL. As of the 00z update we are monitoring
convection across northern Mexico, however, not expecting this to
impact our TAF sites at this time. Southerly winds will pick back
up by mid to late morning on Wednesday. Any IFR ceilings should
bump to MVFR or perhaps even VFR for McAllen, especially by
PREV DISCUSSION... /issued 312 PM CST Tue Feb 20 2018/
SHORT TERM (Now through Wednesday Night): Winds have maintained
their gusty character into early this afternoon, with few gusts
topping 35mph but remaining shy of Wind Advisory criterion.
Earlier, also had to nudge PoP`s up a bit for the remainder of the
afternoon, per radar trends over the eastern counties and near-
term model guidance over the west.
In the larger sense, Texas remains caught in the SSW flow between
the upper-level trough over the western CONUS and the strong high
parked off the SE CONUS; this won`t change drastically in the
short-term. This evening, GFS and HRRR are pretty bullish with
scattered showers and a few thunderstorms over Zapata/Jim
Hogg/Starr counties courtesy of a "ripple" in the H5 flow. NAM is
a bit further north with the ripple, but have leaned away from it
for the near-term. Otherwise, another warm and humid night is in
store with only slight chances of showers for the remainder of the
area. Temps for tonight and Wednesday were changed very little
from the inherited forecast. Regarding Wednesday, flow aloft veers
to more WSW and becomes a bit drier, making the column moisture a
bit more diffuse. Have kept only isolated coverage PoP`s through
Wednesday afternoon. Temps were teased down just a bit, but most
areas will see low-mid 80s with some afternoon breezes (but down a
notch from today with the PGF weakening ahead of an approaching
Speaking of the next cold front, it will be pushing southward
through Texas on Wednesday. 12Z GFS moves it into the
northern/western counties between 00-03Z on Thursday and stalls it
there. 12Z NAM is actually a hare slower but keeps slowly plowing
it forward through the night, essentially bisecting the CWA from
NE-SW by early Thursday morning. Per coordination with other Texas
offices, have leaned into NAM solution for winds/temps/dewpoints
starting Wednesday evening. Some uncertainty here, though. NAM
pushed the last front too far south...but, this time the high
pushing it is stronger (around 1040mb), though still tracks much
more east than south. So, there will be a fairly tight gradient in
min temps from NW to SE Thursday morning, with mid-upper 50s near
APY to around 70 for BRO. Scattered showers and isolated
thunderstorms are expected along and behind the front, with more
isolated activity ahead of it.
LONG TERM (Thursday through Tuesday): Return flow should redevelop
at the coast on Thursday as a West Coast short wave trough pushes
into the Southwest, supporting pressure falls over the southern
High Plains, with rain chances decreasing as a remnant frontal
boundary retreats north. At least that was the original
thinking...per some late-breaking collaboration with other Texas
offices, will lean more toward the colder NAM solution (though
with some uncertainty) for Thursday/Thursday night, which will
leave quite a gradient in temps across the CWA with the boundary
stalled out. Front should finally lift back northward early in the
day on Friday.
The short wave trough will swing deep over the Southwest by
Friday, with continuing southwest flow aloft over the CWA. Thus,
the focus for convection will remain well to the north of the Rio
Grande Valley Friday as the next cold front moves toward south
Texas on Saturday. A surface cold front is forecast to push
through Saturday night, but as mentioned the mid level trough will
be well to the north of the area at that time, and unable to
provide significant supporting upper dynamics. Elevated convection
will develop across the CWA Saturday night with the front.
Moderate north to northeast winds will develop on Sunday behind
the front, with lingering showers. The GFS and the ECMWF differ
slightly on the location/progression and strength of the front,
with the ECMWF slower and weaker than the GFS on Sunday.
Differences seem to decrease somewhat Sunday night, however, with
high pressure settling over the area. High pressure will slide
east on Monday with winds veering to east and southeast by
Tuesday. Mostly cloudy skies will develop and stick around Friday
and beyond, with a chance of rain on Sunday and Monday. The newer
GFS run keeps temperatures lower by 5 to 10 degrees from Sunday
afternoon through Tuesday, though still near to slightly above
MARINE (Now through Wednesday Night): Mainly moderate SE winds
will persist through much of the short-term, with some backing to
more easterly possible ahead of a cold front Wednesday night over
the northern waters. However, persistent SE fetch across the
western Gulf will keep Gulf seas elevated, especially for the
waters 20-60nm out. 6-7 ft. seas will be common, with SCEC likely
to continue and possibly reaching SCA criterion tomorrow night.
Scattered showers and thunderstorms also expected for the northern
waters Wednesday night.
Thursday through Sunday night: Moderate southeast to south winds and
moderate to high seas will prevail through the long term forecast as
high pressure to the east dominates the Gulf. Forecast wave heights
are coming in slightly higher than the short period wind driven
heights one might expect for the predicted wind strength, and it is
possible that some east to southeast longer period fetch component
is being incorporated. Hence, periods of small craft should
exercise caution to low end small craft advisory conditions will
be the rule. A front will move into the area Saturday night into
Sunday, shifting winds to east and then northeast.
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Area Forecast Discussion
National Weather Service Houston/Galveston TX
901 PM CST Tue Feb 20 2018
At 7 PM, a cold front extended from about Paris to Gateville to
Fort Stockton. Scattered showers continue to develop just ahead
and behind the front. Earlier tonight, some moderately heavy rain
fell across Walker, Madison and Houston counties with Wyser Bluff
in Walker county receiving 1.58 between Noon and 7 PM. FWIW, the
radar is underestimating precip and the gages are showing 25-35%
higher totals. At 850 MB, a 45-50 kt low level jet is located
over East TX/West LA with a ribbon of higher moisture across
central LA into central TX. At 300 mb, upper level winds show a
broad split over N-NE Texas. Water vapor imagery shows a well
defined disturbance over northern Mexico. Storms were developing
in advance of this feature and will continue to do so. Both the
GFS/ECMWF show this speed max and this feature will approach the
middle coast placing SE TX in a LFQ. Feel convection will fill in
toward the middle coast tonight and move into SE TX prior to
sunrise. The 00z CRP sounding showed a PW value of 1.81 inches
which is one of the highest values I`ve ever seen in February. The
unseasonably high moisture coupled with the approaching speed max
and a slow moving cold front should set the stage for widespread
showers and thunderstorms early Wednesday. Some of the rain will
be locally heavy. Widespread rainfall of 1 to 3 inches looks
likely over most of the region with some isolated areas receiving
between 3 and 5 inches. Since the 00z models are not all in yet,
will hold off on a Flash Flood Watch but one might be required for
Wednesday morning. Temps are tricky as well and will fall
significantly in the wake of the cold front. Have raised PoPs for
09-12z and bumped up QPF grids. Rest of the forecast is in good
.PREV DISCUSSION... /ISSUED 546 PM CST Tue Feb 20 2018/
AVIATION [00Z TAF Issuance]...
Pretty messy weather expected for the upcoming TAF period.
Ceilings have improved in most areas this afternoon but will
likely fall back down to IFR later this evening and overnight
tonight. The models are suggesting the front and associated
showers and storms may be arriving a little quicker than
previously indicated. Either way, the front will push through CLL
and UTS first with showers and thunderstorms before drifting into
the Houston Metro (IAH, HOU, SGR, CXO) early tomorrow morning and
sticking around for most of the day. Expect rounds of showers and
thunderstorms throughout the day tomorrow, potentially tapering
off to SHRA towards the tail end of the taf period. Ceilings may
improve to MVFR or even VFR briefly before the front arrives, but
should fall back down to IFR in the wake of the front. 11
PREV DISCUSSION... /ISSUED 344 PM CST Tue Feb 20 2018/
NEAR TERM [Through Tonight]...
Radar this afternoon has become more active from Columbus up to
Brenham/College Station to Madisonville. Based on SPC mesoanalysis
data, this activity seems to be rooted within the main moisture
axis of 1.6-1.8 inches of precipitable water. This is also where
the LLJ is the strongest with 850mb wind around 40-50 knots and
850mb dewpoints around 13-14C. This appears to be a more favored
area for convection and training of cells given the deep upper
level flow from the SW.
Upper air analysis shows a deep trough over the western U.S. with
a strong ridge in the western Atlantic. Sandwiched in between is
the Plains where the pattern is supportive of the cold front in
north Texas stalling over the area. However since there are 30-40
degree temperature drops behind the front and the shallow nature
of the front, this front will continue to push south and likely
reach the northern third of the forecast area around 12Z Wed.
Latest HRRR and WRF ARW/NMM all support this idea along with the
NAM. Synoptic models are slower to catch onto this trend. With
this shift in the forecast, temperatures will be falling behind
the front and this means the boundary will be more of a focus for
rainfall. Trends in the NAM and then the last couple of HRRR/RAP13
runs raise some eyebrows with their QPF output. If there is a WRF
model runs that lends support to these trends it might be the 12Z
WRF- ARW from Texas Tech while the NCEP WRF- ARW/NMM show less
precipitation through 12Z Wednesday.
SHORT TERM [Wednesday Through Thursday Night]...
Bottom line: it`s going to rain Wednesday and then begin to taper
off Thursday. From a pattern recognition standpoint, this
forecast for the next couple of days is not that hard. Upper
levels - we have a trough out west with SW jet stream flow and an
approaching jet streak. In fact the beginnings of the divergence
from this jet streak approaches S Texas and SE Texas Wednesday
morning. Deep moisture is in place with high dewpoint air through
the boundary layer. Precipitable water values peak around 1.6 to
1.8 inches which is right at the 30 year climo max for this time
of year. In fact, the 12z CRP sounding from today had a record of
1.61 inches of PW. Now let`s throw in a 30-40 knot LLJ from the
south that lines up normal to an approaching cold front. And
that`s the last ingredient: the cold front is now expected to push
off the coast and stall so there will be lift over the front with
all the deep moisture over the region. So overall, models are in
decent agreement with this pattern going forward. The devil will
be in the details of the mesoscale. That is where the recent
12Z/18Z NAM trends along with the HRRR/RAP may be onto something
that the other models are not resolving. Mesoscale interactions
will be critical as areas of training of storms and favored areas
of convection could shift and likely shift southward from the
original threat area for heavy rainfall. The NAM in particular
shows a meso-low feature forming on the front tied to the
divergence in the jet streak. This meso-low supports heavy
rainfall farther south and a trend to monitor overnight. Of course
the NAM has a history of not performing well in convective
situations, but still a trend to watch.
Heavy rain threat still looks to be for the northern third of the
forecast area from Brenham to Huntsville northward where 2-4
inches of rain look likely through 12Z Friday or a 2 day total for
Wednesday and Thursday. Farther south looks like 1 to 3 inches
are more likely with 1 inch along the coast. This is a little
higher than yesterday`s forecast and on track from the forecast
package from the overnight shift. However there very well could be
a shift southward in the threat area. This means that the
isolated areas of 3 inches could become more common but for now
this will serve as an alternate scenario. Overall confidence
remains in the higher rainfall amounts occurring over the
northern portions of the forecast area. The main impacts will be
still street flooding in urban areas and the usual low lying
areas/underpasses. This includes rural roads in valleys or near
creeks. For more impacts see the hydrology section below.
Thursday the cold front that stalled along or just off the coast
will push back north as a warm front. This will keep rain chances
going in the forecast with mainly elevated convection. PW values
still range from 1.6 to 1.8 inches but should be decreasing
Thursday night into Friday. Upper level forcing also moves off to
the NE which may limit the extent of convection later on Thursday.
There may still be some brief periods of heavy rainfall but not
as many convective clusters moving over the region. Rainfall
amounts look to be more in the tenth to a half inch amounts on
Thursday so the majority of the heavy rainfall threat will be on
LONG TERM [Friday Through Tuesday]...
The warm front that will push through SE TX Thursday, will move
move well north of the region into the NE TX on Friday. Winds will
remain onshore behind this feature, allowing moisture to continue
funneling into the region. Precipitable water (PW)values will
rise back up to 1.3-1.4 inches. Therefore, showers and
thunderstorms will again be possible Friday and Saturday, with the
best coverage north of I-10 Friday into Saturday. Precip coverage
will then shift east by Saturday afternoon, with the best chance
for showers and thunderstorms east of I-45 and south of I-10.
Saturday night into Sunday morning an area of low pressure
associated with a frontal boundary tracks eastward across the
midwest. A Pacific airmass fills in behind this feature, as the
front pushes southward into the region reaching our northern zones
as early as Saturday afternoon. There is some discrepancy between
the global guidance regarding the timing of this front. The GFS
brings the cold front into the region faster than the ECMWF. GFS
also shows cooler temperatures behind the front in comparison to
the ECMWF, as drier air filters into the region. Forecast
soundings show a quick drop in PW values behind the front,
potentially falling as low as 0.4-0.6 inches according to both the
GFS and ECMWF. High temperatures behind the front will range
between the mid 60s-70s, with low temperatures in the low 50s-
Surface high pressure attempts to build back into the region
Monday into Tuesday, and a warming trend will commence.
Temperatures should rise back above normal climatological values
by the beginning of next week. Onshore flow will also return, as
winds turn out of the southeast.
South to southeast flow will continue through Wednesday
afternoon. This will keep the moisture flowing into and across the
coastal waters leading to areas of fog with some dense fog
possible. Have reissued the marine dense fog advisory for the 0-20
nm waters through Noon Wednesday. Improvement will be slow
Wednesday morning. The persistent flow will maintain seas of 5-8
feet well offshore so will extend the SCA through 12z Wednesday.
Winds relaxing as the front stalls which should allow seas to
slowly subside though as the front begins to retreat back
northward from the coastal areas the threat of fog returns
Thursday. The warm moist flow Thursday through Saturday will
likely lead to continued fog issues. Guidance in general shows a
front pushing off the coast early Sunday morning probably ending
the fog threat but with showers and thunderstorms.
Tides will continue to run well above normal though with the
lower amplitude tidal cycle don`t anticipate coastal flooding
In anticipation of heavy rainfall and resulting rises in rivers,
tributaries and bayous, here are some items to consider when
looking at hydrographs and forecasts from the WGRFC. River
forecasts include 24 hours of QPF. Based on the river forecast
output, no basins are expected to reach action stage. WGRFC did
run contingency forecasts with 48 hours of QPF which resulted in
some rises to action and minor flood stages for the Trinity,
Brazos and San Jacinto Rivers. These forecasts hinge on how much
rain ultimately falls upstream and is routed through the river
system so there is still time to monitor conditions and forecasts
for changes. Harris County bayous would need 4 inches of rainfall
or more to generate flooding but this is also dependent upon rain
fall rates and how quickly the rain falls. Bottom line: we will be
monitoring conditions for rises on rivers and bayous but biggest
impact still to be street flooding/flooding of low lying areas and
poor drainage areas.
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 78 54 56 43 59 / 70 90 90 70 60
Houston (IAH) 79 69 74 55 75 / 50 50 90 70 60
Galveston (GLS) 75 65 72 62 73 / 20 30 70 70 50
GM...Dense Fog Advisory until noon CST Wednesday for the following
zones: Coastal waters from Freeport to the Matagorda Ship
Channel out 20 NM...Coastal waters from High Island to
Freeport out 20 NM.
SMALL CRAFT SHOULD EXERCISE CAUTION until 6 AM CST Wednesday for
the following zones: Matagorda Bay.
Small Craft Advisory until 6 AM CST Wednesday for the following
zones: Waters from Freeport to the Matagorda Ship Channel
from 20 to 60 NM...Waters from High Island to Freeport from
20 to 60 NM.
Area Forecast Discussion
National Weather Service Blacksburg VA
954 PM EST Tue Feb 20 2018
A strong ridge of high pressure will remain off the southeast
coast providing much above normal temperatures through the
remainder of the week. Chances for rain increase late Wednesday
into Thursday with a cold front, followed by a better chance of
showers with another front by later in the weekend.
.NEAR TERM /THROUGH WEDNESDAY/...
As of 940 PM EST Tuesday...
Temperatures and dew points are reaching their cross-over point
with fog developing within the next couple of hours, especially
counties along and south of the VA/NC border. Mixing increases
towards sunrise will help remove fog across the mountain
valleys and foothills. The piedmont may carry fog into mid
Not seeing many returns upstream this evening, but models
continue to carry precipitation along the southern Blue Ridge
through the early morning hours. I have lowered PoPs through
midnight, then raised them to 30 percent in the morning. P-type
will be rain or drizzle with very little to measure.
As of 620 PM EST Tuesday...
Updated grids with latest observations. Minor adjustments made
for breezy conditions remaining into this evening. Also made
changes to dew points through the night, especially across
Southside where 60F are being reported (600 PM).
As of 245 PM EST Tuesday...
Much of the area has finally mixed out this afternoon with
residual low clouds stuck across southern sections where a weak
bubble of high pressure persists. Expect these clouds to linger
before again expanding back north and east after sunset when
will also lose most surface mixing. However moisture will remain
quite shallow into the evening so removed any pops early on to
start. Moisture may deepen over far southwest sections later
tonight resulting in some spotty light rain/showers/drizzle
espcly NC mountains per latest HRRR but iffy given little
upslope at this point. Otherwise expanse of low clouds and fog
again the main issues as models show plenty of clouds east of
the Blue Ridge and dense fog where skies stay clear, excluding
the far west where mixing should linger. Does appear that a bit
stronger southwest flow above the surface along with more clouds
early may preclude widespread dense fog, but something to watch
later on. Should be quite a mild overnight given rising
dewpoints and warm temperatures to start most sections. Thus
kept most in the 50s for lows with a few valley 40s.
Weak cold front to the west will be approaching on Wednesday as
the upper ridge attempts to hold tight offshore. Deepening
southwest flow should enhance moisture transport into the area
with forecast Pwats of better than an inch advecting in by
afternoon. Forcing along the front looks quite weak given better
upper support farther west closer to the actual baroclinic zone
in the Midwest. Guidance does show some weak instability
developing as higher dewpoints tend to coincide with heating and
perhaps arrival of a weak pre-frontal type trough/outflow
across the west. Appears enough ridging to hold out east to keep
eastern sections dry so keeping chance pops mainly west for
scattered showers with isolated coverage Blue Ridge. Cant
totally rule out thunder far west but given mostly elevated
instability off soundings will leave out mention for now. Could
be another day of record highs with potential given a warmer
start and similar warm thickness of today to see some upper 70s
if more sunshine is realized out east. Otherwise bumped up highs
mostly into the lower/mid 70s, while leaving areas along the
southern Blue Ridge/foothills cooler per clouds and a late start
due to fog. See the climate section below for details on
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 300 PM EST Tuesday...
A frontal boundary will be sandwiched between high pressure
over the Great Lakes and another high just south of Bermuda.
With this boundary draped over central West Virginia and
northern Virginia by Wednesday night, clouds and showers will be
more likely north of Route 460. Temperatures should remain
considerably mild overnight with 50s and 60s expected for lows.
The upper level ridge responsible for the highly anomalous
warmth should begin to sag southward toward Florida on Thursday.
This change should allow the aforementioned high pressure area
over the Great Lakes to head eastward toward the New England
States and start wedging southward along the eastern slopes of
the Appalachian Mountains. As a result from the influence of
northeasterly flow, the frontal boundary should begin to push
southward as a backdoor cold front east of the Blue Ridge.
Models still disagree on the southward progression of this cold
front during Thursday afternoon through Thursday night, which
adds to the uncertainty for this part of the forecast. In
addition, Friday becomes more questionable due to differences in
how quickly the northeasterly flow retreats once high pressure
heads offshore and the frontal boundary lifts back northward as
a warm front. The latest GFS and NAM solutions continue to show
the backdoor cold front reaching the Virginia and North Carolina
line by Thursday night and not allowing it to leave until
Friday afternoon. The ECMWF, however, sends the cold front just
toward Route 460, which leads to a faster erosion of the wedge
on Friday and significantly warmer and drier conditions.
Confidence is higher that the more significant wedge event will
take place. Thus, a non-diurnal temperature trend with more
clouds and showers affecting most of the Piedmont will be
advertised in this update for Thursday and Friday. Friday night
should stay dry as the aforementioned high pressure area south
of Bermuda nudges westward toward the Mid Atlantic.
.LONG TERM /SATURDAY THROUGH TUESDAY/...
As of 300 PM EST Tuesday...
A low pressure system will organize over the lower Mississippi
River Valley on Saturday and track eastward toward the Mid
Atlantic by Sunday. Model solutions continue to slow the timing
of this frontal passage for our area, which appears to be during
Sunday afternoon based on the GFS. Chances of rain were lowered
a little on Saturday but increased a fair amount for Sunday. It
is worth noting that the ECMWF solution is a little slower with
the cold front than the GFS as it displays a Sunday evening
frontal passage. Therefore, some questions remain on how much
the moisture could linger into Sunday night and Monday morning,
especially in northwest North Carolina. Eventually, high
pressure should build overhead toward Monday afternoon. The
upper level pattern turns more zonal by Tuesday, which looks dry
with plentiful sunshine at this point. Temperatures still will
reside well above normal throughout this period although it
should turn a little cooler by early next week.
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
As of 625 PM EST Tuesday...
Models again show low clouds filling back in beneath the
inversion overnight with low-end MVFR to LIFR across most of the
region by midnight. Fog also likely again late tonight but
widespread IFR vsbys iffy with a bit more pronounced southwest
trajectory just above the surface layer overnight. Latest HREF
has lower vsbys initially this evening before mixing out to
mainly just along the southern Blue Ridge late. Therefore opted
to go with more of a MVFR range in vsbys for now.
The only place that should remain VFR throughout the period is
KBLF although some VFR cigs likely to affect that area late
tonight into Wednesday ahead of the next cold front.
Low clouds will again be slow to exit eastern sections on
Wednesday given only light southwest flow and deeper moisture.
Also a band of pre-frontal moisture likely to affect the far
western sections by midday although appears any showers should
hold off until after the valid TAF period so not including
mention. Otherwise plan to keep most sites under MVFR/IFR cigs
Wednesday morning with most improvement in cigs near the Blue
Ridge where in between trapped moisture to the east and the
frontal moisture to the west. A stronger cold front looks to
arrive on Sunday from the west with a better coverage of showers
including continued periods of sub-VFR.
Extended Aviation Discussion...
May again see widespread sub-VFR develop again Wednesday night
as the front approaches but stalls allowing better pooling of
moisture under weak south/southeast flow.
Lingering MVFR or worse conditions in showers likely Thursday
with the cold front spilling south into the area. This front
lifts back north Friday with continued threat of showers and
potential low clouds. This front will linger nearby into
Saturday with a continued threat of showers, but cigs/vsbys
should a little better south of the front.
As of 330 AM EST Monday...
This afternoon and Wednesday will feature well-above normal
temperatures that may approach or eclipse daily record highs and
daily record high minimum temperatures. It`s also possible that
all- time warmest February minimum temperatures could be
approached or broken in this period.
Following are daily records, as well as the all-time warmest minimum
temperatures recorded in the month of February, for our five
climate sites with long-established periods of record:
Site MaxT Year HiMin Year
BLF 67 2017 48 1994
DAN 74 1971 51 1949
LYH 76 1930 59 1939
ROA 75 1939 54 1971
RNK 69 2017 47 1991
Site MaxT Year HiMin Year
BLF 65 1996 54 1997
DAN 75 2011 55 1953
LYH 75 1930 50 1981
ROA 73 1930 48 1997
RNK 71 1986 49 1953
Warmest HiMin - February:
Site HiMin Date
BLF 57 Feb 5 2008
DAN 60 Feb 18 2008
LYH 59 Feb 20 1939
ROA 57 Feb 12 1932
RNK 52 Feb 16 1990
Area Forecast Discussion
National Weather Service Shreveport LA
915 PM CST Tue Feb 20 2018
Not seeing the bowing/discrete structure in the pre-frontal
storms we saw earlier this evening across portions of Northeast
Texas into Southwest Arkansas with the prefrontal activity quickly
decreasing in coverage and intensity. What is continuing to
blossom is the convection immediately on the front and in the wake
of the frontal boundary with regional radar mosaics showing
convection well west of the I-45 Corridor of Central Texas.
Latest 00z NAM output showing the frontal boundary, which as of
03z was oriented near a DeQueen, Arkansas, Mineola, Texas line,
will continue moving very slowly south and east overnight and
should be just northwest of the Shreveport/Bossier City metro area
by 12z Wed. Thus, convection should continue to build and expand
south and east overnight, encompassing all but our southeast half.
There is good agreement in the latest HRRR and 00z NAM that our
southeast zones should see very little if any precipitation
overnight so have lowered pops across these zones. Otherwise kept
heavy rainfall wording across the Watch area overnight with the
heavier downpours likely not reaching Northwest Louisiana until
near or shortly after sunrise.
Updated hourly grids to mimic current conditions and to account
for the frontal movement into our northwest zones but otherwise,
forecast is in good shape.
Update out shortly...13.
.PREV DISCUSSION... /issued 554 PM CST Tue Feb 20 2018/
For the 21/00z TAFs, convection is likely to affect all TAF sites
this period as a strong cold front gradually move into and across
the area. Flight conditions will vary initially, but IFR/LIFR
ceilings and visibilities are expected at most sites, especially
after 21/06z, as the convection spreads southeast across the
region. The front will become stationary across the area, which
should allow showers and thunderstorms to prevail at most TAF
sites for much of the period.
Note: Amendments are not currently scheduled for KELD because the
ASOS is down, and there are no backup observation facilities.
.PRELIMINARY POINT TEMPS/POPS...
SHV 64 66 54 67 / 90 100 100 60
MLU 67 72 57 72 / 30 100 100 80
DEQ 46 51 46 55 / 100 100 80 70
TXK 53 55 47 57 / 100 100 100 60
ELD 62 64 49 63 / 90 100 100 80
TYR 47 54 47 58 / 100 100 80 70
GGG 54 59 51 65 / 100 100 90 70
LFK 66 69 56 71 / 80 100 90 60
AR...Flash Flood Watch through late Wednesday night for ARZ050-051-
LA...Flash Flood Watch through late Wednesday night for LAZ001>004.
OK...Flash Flood Watch through late Wednesday night for OKZ077.
TX...Flash Flood Watch through late Wednesday night for TXZ096-097-