Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/18/17
Area Forecast Discussion
National Weather Service Lake Charles LA
825 PM CST Fri Feb 17 2017
.DISCUSSION...
Inflow into approaching surface trof across the NW Gulf off the SE
TX/SW LA coast around 20-25 kts (per platform reports) outside
the thunderstorm area, special marine warning within this line of
thunderstorms. Expecting winds to diminish within the next couple
of hours to 20 knots or below. Not anticipating the need for a 2
hour SCA, but updated forecast to expand Small Craft Exercise
Caution to include 0-20 nm zones. Also, redistributed pops across
the coastal waters for this based on latest HRRR reflectivity
guidance, which still indicates most of this activity diminishing
by 06z or midnight.
DML
&&
.PREV DISCUSSION... /issued 655 PM CST Fri Feb 17 2017/
DISCUSSION...
Wx map shows surface trof and upper level disturbance axis over
East Texas this evening, continuing to move east, with showers
and thunderstorms along and southeast of the axis. Main area of
showers and thunderstorms over lower Acadiana into the eastern
coastal waters, with a secondary cluster of thunderstorms off the
Southeast Texas coast right along the trof axis. Thus, updated
forecast this evening over SE TX/SW LA into the adjacent coastal
waters for higher pops the next few hours, trimming down from NW
to SE towards midnight into the overnight hours.
DML
PREV DISCUSSION... /issued 529 PM CST Fri Feb 17 2017/
AVIATION...Rain will continue to move east across the region for
the next few hours. Lower vis in rain can be expected, however for
the most part the visibility will remain above 3 miles. Lower
ceilings are expected through tonight.
PREV DISCUSSION... /issued 443 PM CST Fri Feb 17 2017/
DISCUSSION...
Upper low over the Red River Valley with a trailing trof quite
evident in water vapor satellite imagery to our west. The trailing
trof axis is TX starting to take on a bit of a negative tilt as
it pivots TWD E TX this afternoon. The upper low is progged to
continue slowly off TWD the ENE tonight, with the with the trof
axis crossing the area this evening. Rain with embedded heavier
convective cells, including isolated thunderstorms, will continue
along/ahead of this axis, ending from west to east during the
evening hours. Low level moisture will linger behind, however,
and there is some potential for patchy fog formation overnight
into SAT morning, but at this time have leaned more toward a very
low cloud deck while maintaining a slight chance of rain.
Deepening westerly flow south of the upper low on SAT will
gradually erode the low level MSTR save for a SFC layer
maintained by southerly onshore winds. Cloud cover will become
more scattered by the afternoon hours, with temperatures climbing
into the upper 70s/near 80. Heights will build SAT night into SUN
as this upper low weakens and accelerates off to the E while a
robust upstream upper trof reaches the Four Corners. Increasing
and deepening moist southerly flow will gradually overspread the
area on SUN as the upper trof slowly moves east of the four
corners, with PWATs climbing to near 2 inches over E TX by early
MON morning, which is plus 2 to 3 standard deviations above the
norm. Fueled by this copious MSTR, despite progged limited
instability, the otherwise broad synoptic lift augmented at times
by a noisy and difluent flow aloft, is expected to yield a
widespread N-S oriented swath of rain and embedded heavier
convective cells/TSTMS developing over E TX late SUN night. There
remains some spread in the global model guidance to contend with
in terms of the timing of the heaviest rain, with the quickest
solution having the onset in my E TX zones after midnight SUN and
the slowest not getting it east of the Atchafalaya until TUE
morning. The overall consensus at this time is for primarily a
Monday event, with the swath of HVY rain entering E TX MON morning
and exiting to the east MON evening. Areawide totals of 1 to 3
inches with locally higher amounts are possible.
Rain chances linger but decrease TUE into WED as the base of the
TROF closes off and tracks SEWD across the GULF. Dry and warm THU
into FRI as a narrow ridge builds in behind the departing upper
low and ahead of another incoming trof.
13
MARINE...
Showers and thunderstorms will continue to affect the Gulf waters
the rest of this afternoon through this evening as an upper trof
over Texas and Oklahoma pivots through the region. This activity
will come to an end after midnight once the trof axis passes,
with the modest southeast winds over the central and eastern Gulf
waters also subsiding. Dry weather and light south winds are
expected on Saturday. Sea fog may become an issued over the
nearshore waters/coastal lakes and bays by Saturday night as very
moist air is transported atop the cooler shelf waters. Winds are
expected to increase Sunday with the approach of another upper
level trof, which is forecast to result in widespread showers and
thunderstorms Monday into Monday night. Rains are expected to
linger but decrease in coverage Tuesday and Wednesday, while winds
become northerly as an area of surface low pressure develops over
the central Gulf.
13
&&
.PRELIMINARY POINT TEMPS/POPS...
AEX 54 76 58 81 / 20 10 10 10
LCH 58 76 63 79 / 30 10 10 10
LFT 58 78 62 81 / 40 10 10 10
BPT 60 79 65 79 / 40 10 10 20
&&
.LCH WATCHES/WARNINGS/ADVISORIES...
LA...None.
TX...None.
GM...SMALL CRAFT EXERCISE CAUTION until midnight CST tonight for
GMZ450-452-455-470-472-475.
&&
$$
PUBLIC...04
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
905 PM CST Fri Feb 17 2017
.UPDATE...
Issued at 905 PM CST Fri Feb 17 2017
Forecast appears to be on track with only minor adjustments made
into Saturday.
Upper level LOW is located over eastern OK this evening with an
area of rain on its downstream flank with the northern extent near
the intersection of MO-KS-OK. The LOW center is expected to track
E-NE thru far southeastern MO around midday Saturday and into the
OH Valley Saturday night.
Scattered WAA showers associated with this LOW are still expected
to move into southeast MO late tonight and continue past daybreak
with a transition at some point toward late morning to an attempt
at getting a deformation zone of stratiform pcpn going in nearly
this same area. It is at this point where a few tweaks to the
forecast were made--expanding the northern coverage a bit into
STL metro and most of the I-70 corridor for some sprinkles
possible late Saturday morning and into the afternoon.
Otherwise, temps left alone for most areas from previous forecast.
TES
&&
.SHORT TERM... (Through Late Saturday Afternoon)
Issued at 234 PM CST Fri Feb 17 2017
The main item of interest over the next 24-30 hours will be the
threat of any rainfall associated with the lifting upper low
currently located over the southern Plains. Model consenus shows
the upper low lifting east-northeast tonight to the vicinity of the
NW AR/SW MO border by 12Z Saturday, and then into the TN Valley by
early Saturday evening. The increase in clouds with this system will
contribute to mild temperatures tonight with most locations only
experiencing lows in the 40s, and some record high mins will be
possible. The unseasonably warm temperatures (+20 to +25 degrees
above average) will continue on Saturday as well, however the
greater cloud cover should temper the max temp readings back a bit
from those experienced the last few days.
Rainfall is a little more iffy. Weak large scale ascent associated
with the upper low spreads into southeast MO and southern IL
overnight and persists to varying degrees on Saturday morning. The
low levels however are quite dry and moisture will be largely
confined to the mid-upper levels. I prefer the RAP depiction of this
and thus some scattered rain showers seem the most probable scenario
across parts of southeast MO and southern IL, with the probability
diminishing and shunting east in the afternoon with the progression
of the upper system.
Glass
.LONG TERM... (Saturday Night through Next Friday)
Issued at 234 PM CST Fri Feb 17 2017
Upper ridge to build into region Saturday night, so will see dry and
above normal temperatures through the rest of weekend and into early
next week. Near record highs Sunday and Monday in the upper 60s to
mid 70s.
By Monday, upper ridge begins to move off to the east as next
weather system approaches. So will see low level moisture on the
increase as well as decent instability for our area. But still have
the issue with split flow aloft, models continue to lift the
northern stream wave out faster through the Great Lakes region,
while southern stream closed low tracks eastward slowly. However,
12z model runs are a bit more optimistic with two streams phasing
together, giving us better chances for rain early Monday morning
through Tuesday morning. Could see scattered/isolated thunderstorms
Monday afternoon/evening, mainly over central/northeast MO, as well
as west central IL, so added thunder mention there.
Weak boundary washes out over region for mid week with zonal flow
aloft, so will see slightly cooler highs in the mid 60s to low 70s.
Next system to approach area on Thursday with strong cold front
moving through Friday. This is when we will have our best chances of
showers and a few thunderstorms. Highs will dip down into the low
50s to mid 60s by Friday, but still above normal for this time of
year.
Byrd
&&
.AVIATION... (For the 00z TAFs through 00z Saturday Evening)
Issued at 545 PM CST Fri Feb 17 2017
VFR conditions and southwesterly surface winds will prevail at the
TAF sites thru the valid period. An upper level storm system will
pass to our south late tonight and Saturday morning, and should
result in some rain shower development, but this currently is
expected to remain to the south of the TAF sites, but if any one
area and time has a greater chance than the others, it is the STL
metro sites around 12z. Will monitor observations and the latest
model data for any adjustments and inclusion of rain mention in
the TAFs this evening.
TES
&&
.CLIMATE...
Record Highs
2/17 2/18 2/19 2/20
STL: 77/1911 74/1971 77/2016 78/2016
COU: 74/2011 71/1930 76/1930 76/2016
UIN: 72/2017 68/1971 71/1930 72/2016
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
704 PM EST Fri Feb 17 2017
.UPDATE...
00Z water vapor and H4 RAP analysis shows a complex upper
level pattern over the CONUS this evening. Very strong
Pacific jet is arriving over the California coast...with
highly diffluent flow. This diffluence is aiding lift and
resulting in significant flooding rainfall across portions
of the western states. The southern half of this flow leads
into a negatively tilted trough/upper low pivoting through
the southern plains/lower MS Valley this evening. WV
imagery/radar and lightning detection show some fairly
vigorous convection ongoing ahead of this energy over the
north-central Gulf of Mexico. The height falls advancing
along the NW Gulf coast today have helped to build the
downstream ridge over our region...and this ridging will
hold overnight and help keep our forecast dry and benign
into early Saturday morning.
At the surface...high pressure centered just east of the FL
peninsula will be slow to give up influence on the region
overnight/Saturday morning. Eventually the approach of the
upper trough and an associated surface reflection/trough
will push this ridge further south/east...but not really
until later Saturday afternoon.
So...the forecast for the overnight hours will remain dry
and seasonable in terms of temperatures. Initial height
falls and associated synoptic lift support aloft associated
with the approach of the upper trough will barely have
enough available column moisture to produce
clouds...nevermind precipitation.
Very slowly through the day on Saturday...the column will
moisten with high clouds becoming middle clouds and so on...
The ensemble guidance as of right now suggest the best
synoptic lift by the time enough moisture is available will
be confined to the northern half of the FL peninsula...and
it will be this area that sees the best potential for
anything more than sct light showers. Even our far northern
zones (while expecting rain)...should not expect significant
amounts of rain. The totals should decrease quickly down
toward the I-4 corridor...and even more further south. Looks
as through the first showers may begin up toward the Nature
Coast perhaps toward midday...and then during the
afternoon/early evening as one heads further south and east.
Overall...this event does not look to be significant in
terms of rainfall for our area...but rather nuisance type
showers for a weekend day. Luckily...the second half of the
weekend looks to be salvaged...as the upper trough axis
moves east of the region by Sunday morning...with synoptic
suppression/drying arriving arriving overhead from the west
and northwest. The forecast for Sunday into the early
portion of the upcoming work week looks dry and increasingly
warm before the next potential for rainfall arrives during
midweek.
Have a great Friday evening and a fun/safe weekend everyone!
&&
.AVIATION...
Significant restrictions are not anticipated through the TAF
period at west-central and southwest Florida terminals.
Prevailing VFR and light winds can be expected through at
least 08/09Z for all terminals...thereafter...a brief
period of MVFR Vis is possible at KPGD. General VFR
conditions are expected for the daylight hours of
Saturday...although ceilings will be lowering (but generally
staying above 3KFT). The potential for sct mainly light
showers will increase for KTPA/KPIE/KLAL/KSRQ after
18-20Z...with only isolated showers expected further south.
&&
.Prev Discussion... /issued 255 PM EST Fri Feb 17 2017/
SHORT TERM (Tonight - Saturday)...
Upper level ridging extends from southern Florida northwest over the
southeast states, through the Mississippi River Valley. This ridge
slides east through the night as an upper low and troughing located
over Texas moves toward the region. Surface high pressure located
over the Florida peninsula slides east by Saturday morning and will
be located north of the Bahamas. A surface low moving east along
the northern gulf coast will produce rainshowers along the Nature
Coast mid morning on Saturday and will progress east-southeast
through the day with rainfall starting late afternoon/early evening
for Tampa Bay northward. The highest POP`s will take place north of
the I-4 corridor and over the northern coastal waters. Overnight
temps tonight are expected to be 8-10 degrees warmer than what we
saw last night. The daytime highs on Saturday will be very similiar
to what we saw today, with highs in the mid 70`s to low 80`s.
MID/LONG TERM (Saturday night through Friday):
The ridge continues to break down as a fast moving
shortwave over the Tennessee Valley quickly pushes off to
the east and moves off the Carolina coast. The associated
upper level energy pivoting around this low will be the
driver for showers and a few thunderstorms Saturday night
with the best chance for rain north of the I-4 corridor. A
second midlevel vorticity max will slide through north
Florida early Sunday morning which will provide enough lift
for a few lingering showers. A strong upper level ridge
builds in the wake of the trough with dry and hot
temperatures through Tuesday.
The progressive pattern continues in the second half of the period
with a stacked cutoff low strengthening in the Gulf of Mexico. The
GEFS and GFS deterministic solution have come into better
agreement with the 12Z European run in the placement and evolution
of the system on Wednesday. The current thinking is a more southerly
track from 24 hours ago which would place the heaviest rain threat
in Southwest Florida on Wednesday. Nevertheless, this system will likely
produce heavy rains and thunderstorms. The exact placement of the low
will be critical for our impacts in West Central Florida.
MARINE...
High pressure has set up over the eastern Gulf of Mexico allowing
for perfect boating conditions this evening. Winds are expected to
be 10 knots or less, becoming light and variable overnight. An area
of low pressure approaches the coastal waters on Saturday and will
produce increasing chances of rain and thunderstorms through the day
on Saturday. Winds will also be on the rise as they shift to the
southeast through southwest around 10-15 knots ahead of the low
pressure system. Conditions improve once again late Saturday into
Sunday as high pressure builds back into the area. The only other
concern will be with red tide along Sarasota County beaches. A Beach
Hazard Statement will be extended until Sunday evening.
FIRE WEATHER...
After seeing relative humidity values in the 20-30 percent range
today, RH values will be on the increase overnight and into the
weekend, which will preclude any need for a Red Flag Warning.
Similiar to what we have seen the past few nights, fog will be
possible in fog prone areas, especially near the wild fires in Polk
County. An area of low pressure moves across the peninsula on
Saturday producing increasing rain chances with the highest chances
along the Nature Coast north of the I-4 corridor. With the
increasing chance of rainshowers on Saturday, it should help to
suppress any remaining smoldering wild fires in Polk County. No
other fire weather concerns expected through the period.
&&
.Preliminary Point Temps/PoPs...
TPA 56 74 64 79 / 0 30 50 10
FMY 56 81 66 84 / 0 10 20 20
GIF 54 80 63 82 / 0 20 50 10
SRQ 54 74 63 78 / 0 20 40 10
BKV 45 76 58 80 / 0 30 60 10
SPG 59 75 65 78 / 0 30 40 10
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...Beach Hazards Statement through Sunday evening for Coastal
Sarasota.
Gulf waters...None.
&&
$$
UPDATE/AVIATION...Mroczka
PREVIOUS DISCUSSION...WYNN/NORMAN
Area Forecast Discussion
National Weather Service Topeka KS
511 PM CST Fri Feb 17 2017
...AVIATION UPDATE...
.SHORT TERM...(This evening through Saturday)
Issued at 322 PM CST Fri Feb 17 2017
Upper low was observed via water vapor imagery rotating through
Oklahoma, lifting mid level moisture into southeast Kansas. Surface
trough axis shifting east towards the Great Lakes region will shift
gusty southerly winds towards the north after sunset. Ahead of this
weak boundary, temperatures have warmed into the lower 70s while
dewpoints mixed down into the lower 30s. Topeka broke the record
high at this hour with a high temperature of 77 degrees. This has
resulted in RH values near the 20 percent range for most of the CWA.
Much of the remained underneath the Extreme fire danger category
given the slightly weaker winds than yesterday, with the exception
of the Emporia area that recorded a peak gust of 34 mph.
For tonight, winds calm, becoming light and variable as a ridge axis
drifts southward into northern KS. Potent, incoming upper trough
across California will shift the upper low northeast and therefore
increase cloud cover towards southeast Kansas Saturday morning.
These clouds should dissipate as the low exits into Missouri during
the afternoon, bringing mostly sunny skies and light winds across
the CWA. Highs may be slightly cooler, given the weaker winds,
however still well above normal in the upper 60s. Increasing
moisture from the departing system lowers the fire danger threat
during the afternoon.
.LONG TERM...(Saturday night through Friday)
Issued at 322 PM CST Fri Feb 17 2017
The mid and long term period continues to look much warmer than
normal with focus on two storm systems Sunday night into Monday
and again Thursday into Friday. While there will be some
fluctuations in airmass temperature with the influx of the
trough-ridge-trough-ridge-trough pattern, the overall high and low
temperatures will remain quite warm at least through the middle of
next week. Normal highs are in the mid to upper 40s this week with
lows in the middle 20s but actual high temperatures will be in the
60s to 70s and lows mainly in the 40s or even low 50s.
The first storm system on Sunday night will see a pretty good
influx of moisture throughout the column but the two main elements
of forcing will split with one short wave trough lifting quickly
north into the main jet stream while the other more significant
chunk of energy will close off into the Gulf of Mexico. The local
forecast area will largely fall in between the two areas of best
forcing but with ample moisture and even some instability, expect
to see at least scattered showers and thunderstorms. Instability
is unlikely to be impressive given rather weak mid level lapse
rates but there are some indications that a few hundred J/kg of
MUCAPE will be expected so have included thunder potential
throughout the period.
The second storm system appears likely to be more impressive with
a strong jet streak forecast to move into the Plains with a
deepening upper low over the Central Plains. The current storm
track is a bit farther north than previous model runs with the
heart of the low tracking over Nebraska and a bit less
precipitation locally. I think the main takeaway point at this
time is that there is a good chance for a strong storm system to
develop at the end of next week, with both winter weather and
thunderstorms possible with this storm, but substantial
uncertainty in the storm track. Much cooler air is likely to
filter in behind this storm...with temperatures becoming near or
below normal.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday)
Issued at 511 PM CST Fri Feb 17 2017
Have a VFR forecast persisting with models showing no real forcing
from the upper low impacting the terminals. However there is some
concern with low level moisture advection progged through the
morning across east central KS. RAP and NAM forecast soundings
show the possibility for some stratus or fog to form by Saturday
morning. It is not out of the question with some 40 degree
dewpoints already moving into south central KS. There could be
some radiational fog if skies remain clear. But confidence is low
since low level winds will be weaker and the surface low
remaining to the southwest. Also the mid and high clouds may
spread north limiting the radiational cooling. Will need to
monitor this potential through the evening and amend accordingly.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Prieto
LONG TERM...Barjenbruch
AVIATION...Wolters