Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/23/17
Area Forecast Discussion
National Weather Service Bismarck ND
934 PM CDT Fri Sep 22 2017
.UPDATE...
Issued at 934 PM CDT Fri Sep 22 2017
Shower activity centered on western SD as of 02 UTC is associated
with the next impulse expected to move northeast into ND tonight.
The forecast is generally on track, but once again we focused on
refining PoPs with this update, particularly relying on iterations
of the HRRR through its 01 UTC cycle since it appears to be doing
the best job assimilating current radar returns in southwest ND.
Lingering steep lapse rates aloft may still support thunderstorms
in the southern James River valley as the impulse reaches there,
but forecast soundings taken across Dickey County from the 00 UTC
NAM and recent RAP cycles suggest MUCAPE will be limited to 200 to
700 J/kg, and that will be driven by parcels originating above 700
mb, with resultant small normalized CAPE supportive of only a low
(though certainly non-zero) probability of a strong storm in that
area.
UPDATE Issued at 645 PM CDT Fri Sep 22 2017
Elevated convection increased in coverage from Stutsman into
Foster Counties late this afternoon, on the nose of the strongest
mid-level warm air advection centered near 850 mb per RAP-based
guidance. That forcing is expected to be the primary driver of
precipitation through the evening and so we refined PoPs slightly
accordingly with this update, focusing on that area northward
toward Rolla. Earlier brief subsidence in the wake of what
appeared to be an eastward-propagating gravity wave per
preliminary, non-operational GOES-16 visible satellite imagery
has shifted eastward. The exit of that mesoscale subsidence also
likely contributed to the convection, but the warm air advection
is also forecast to refocus eastward by mid evening and so that
will cause precipitation chances to dwindle until after 06 UTC,
when another vorticity maximum embedded in southwest flow aloft
will reach southern ND. Some recent HRRR simulations suggest a
strong storm could affect Dickey and LaMoure Counties with that
wave late tonight, where MUCAPE will likely still be sufficient
for isolated stronger, elevated updrafts.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 139 PM CDT Fri Sep 22 2017
Scattered showers and thunderstorms will continue through the
evening hours for most of western and central North Dakota. Later
tonight precipitation shifts south and east as the surface trough
swings into Minnesota. With ample elevated instability, shear and
a low freezing level, several storms could produce marginally
severe hail this afternoon and evening. A very cool night is in
store with northerly winds and temperatures in the 30s and low
40s for most.
.LONG TERM...(Saturday night through Friday)
Issued at 139 PM CDT Fri Sep 22 2017
The main focus for the Long term will be cooler temperatures with
a good chance for showers Saturday and Sunday. The cool weather
will last at least through next Tuesday. Highs during this period
will be in the 50s and lows in the mid 30s to mid 40s. There could
be some patchy frost during this period. Chances for showers will
continue through Tuesday until the upper trough finally moves
through. Then moderating temperatures at least into the 60s are
expected with mainly dry weather for Wednesday and Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 934 PM CDT Fri Sep 22 2017
MVFR ceilings are expected to become widespread across western and
central ND tonight and Saturday morning. Local IFR ceilings are
possible. Showers are possible in southwest and south central ND
tonight, with a few thunderstorms also possible south of KJMS. A
more widespread area of rain is expected to develop in southwest
ND Saturday afternoon as a stronger disturbance approaches.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...CJS
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...CJS
Area Forecast Discussion
National Weather Service Dodge City KS
615 PM CDT Fri Sep 22 2017
...Updated aviation discussion...
.SHORT TERM...(This afternoon through Saturday)
Issued at 1235 PM CDT Fri Sep 22 2017
Atmosphere is more humid and unstable this afternoon compared to
previous days, as the dryline has backed up to the CO/KS border
vicinity. The dryline and its associated convergence will remain
near these western zones through peak heating, where various
models and CAMs including the latest iterations of the HRRR
develop scattered convection by around 4 pm. Most activity is
expected to remain west of US 83 through this evening. SPC 5%
wind/hail probability is plausible, with marginal MLCAPE of
1000-1500 J/kg and marginal bulk shear around 30 kts. East of the
dryline, the south to southeast winds will continue to blow this
afternoon, in response to another round of lee cyclogenesis east
of Denver. S/SE winds will again gust to near 40 mph through
early evening. Temperatures still unseasonably hot, and
approaching record levels again this afternoon, well into the 90s.
Tonight...Breezy and unseasonably warm again. Any evening
convection across the western zones will diminish rapidly with the
loss of heating and convergence. Still, with various disturbances
embedded in the SW flow aloft in proximity to Colorado, kept some
pops going in the western zones all night. Locations east of US 83
expected to remain dry. S/SE winds will remain elevated and gusty
again tonight in response to another low level jet. With winds
keeping the boundary layer mixed and preventing radiational
cooling, another unseasonably warm night is on tap, with
temperatures struggling to get below 70 through sunrise Saturday.
Saturday...Closed low in Nevada remains essentially stationary
through the daylight hours. In other words, forcing for ascent
needed to encourage convection will be in no hurry to come into
SW KS. Still, 12z NAM and other guidance generate a line of
showers and thunderstorms near/west of the CO/KS state line by
6 pm, with this convection making some slow progress eastward to
near the US 83 corridor Saturday evening/night. Areas along and
especially east of US 283 will have to be patient, as those areas
are expected to remain dry through Saturday night. Otherwise, the
persist strong south winds will blow yet again on Saturday,
averaging 20-30 mph with gusts near 40 mph. Temperatures will
begin to cool down, as 850 mb temps drop 2-3C, and models depict
much more cloud cover (especially the western CWA). Afternoon
temperatures will range from the upper 70s along the Colorado
border, to the mid 80s at Dodge City, to near 90 eastern zones.
Just the beginning of a cooling trend that will continue through
the long term.
.LONG TERM...(Saturday night through Friday)
Issued at 208 PM CDT Fri Sep 22 2017
Still on track to pick up some sorely needed rainfall in SW KS
Sunday and Monday. Closed low over Utah Sunday morning finally
ejects slowly NE to southern Wyoming late Sunday. Forcing for
ascent needed to generate precipitation will slowly progress west
to east Sunday through Sunday night, with several rounds of
showers and thunderstorms anticipated. Blended model pop fields
continue in the likely category, and these were accepted.
12z ECMWF solution depicts showers and thunderstorms along and
west of US 83 at sunrise Sunday, progressing west to east across
SW KS daylight Sunday. QPF grids show 1/2 to 1 inch of rain
possible daylight Sunday. With thick clouds and rainfall,
temperatures will cool sharply Sunday, to 70s west and 80s east.
Another round of rain and thunderstorms is expected Sunday night
into Monday, as the associated cold front boundary sags into
Kansas and frontogenetic forcing is enhanced. Another 1/2 to 1
inch of rain is forecast, and much of this rain will fall where it
is needed the most, across the central and eastern counties. Winds
will become northerly by Monday morning.
Monday...Cloudy and much cooler, with afternoon temperatures
holding in the 60s NW to the 70s SE. Frontal boundary will sink
well south of SW KS, but models depict adequate moisture
overrunning north of the boundary to keep rain and isolated
thunder going much of Monday, particularly the SE zones. Another
1/2 to 1 inch of rain is possible daylight Monday. Storm total
QPF grids continue to come up widespread rainfall amounts of
1-2 inches across SW KS. Of course, given the nature of
convection, some areas will receive more than that, some areas
less.
Tuesday...Dry weather returns, as cool/dry high pressure sinks
south into the central plains. Fantastic, crisp fall weather is on
the way next week, with afternoon temperatures within a few
degrees of 70, and lows down into the 40s.
Wednesday through Friday...Dry. Let`s hope we get the rain Sunday
and Monday. Models are consistent showing dry quiet weather late
next week, with a weak cutoff low meandering over the Desert SW
and weak dry flow over SW KS. Pleasant early fall weather on the
way with highs only in the 70s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 615 PM CDT Fri Sep 22 2017
Gusty surface winds will persist into the late evening hours at
all the terminals. Through the overnight hours, LLWS will become
more of an issue as surface winds diminish somewhat and 45-50
knots winds continue a few thousand feet AGL. Isolated to widely
scattered thunderstorms currently forming over far southwest
Kansas into the west Texas Panhandle should stay west of the
Garden City and Liberal terminals this evening before dying out.
There will be a slight chance for thunderstorms over far southwest
Kansas late tonight into Saturday but will forego mentioning in
the TAFs at this time given the sparse coverage.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 70 86 66 80 / 10 20 30 60
GCK 67 84 62 76 / 20 50 70 70
EHA 62 79 58 75 / 40 60 70 60
LBL 68 84 65 76 / 20 40 60 70
HYS 72 87 68 80 / 10 20 30 60
P28 70 89 68 86 / 0 10 0 30
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Turner
LONG TERM...Turner
AVIATION...Gerard
Area Forecast Discussion
National Weather Service Hastings NE
713 PM CDT Fri Sep 22 2017
.SHORT TERM...(This evening through Saturday)
Issued at 313 PM CDT Fri Sep 22 2017
Fire danger will remain near critical early this evening for
western zones especially west of Kearney, to Franklin, to
Osborne. The winds are very strong gusting into the 30 to 40 mph
range. The only thing preventing a red flag warning this afternoon
and evening remains the relative humidity values, which are near
that critical 20 percent, but for the most part just above it.
Am not impressed with thunderstorm chances this evening, but will
allow the slight chances to remain across our far northwestern
zones from Beaver City to Greeley and points west. The HRRR model,
which typically over does convection is showing little to nothing
happening with just a few warm sector heat of the day
thunderstorms early this evening and then dry through the
remainder of the night. The 12Z and 18Z NAM continue to highlight
just a slight convective signature over our far west this
evening. Therefore, will continue to go with our slight
thunderstorm chances in our far west, but believe most folks will
remain dry. There is modest instability and fairly high wind
shear this evening so can not rule out a severe thunderstorm or
two should thunderstorms form in the warm sector, but forcing is
fairly weak in the warm sector.
Saturday...There will be more in the way of cloud cover, which
will knock a solid 5 to 10 degrees off of our highs. However, it
will still be above normal for this time of year with our
forecast area in the warm sector allowing highs to climb into the
80s and perhaps close to 90 in some eastern zones. The best chance
for rain will be later in the afternoon and evening generally
west of a Beaver City, Kearney, Greeley line. Can`t rule out an
isolated shower or thunderstorm in the warm sector around the
Tri-Cities, but likely not to big of a deal. Instability will be
more limited and there is just a small chance of a marginally
severe storm across our northern and northwestern zones.
.LONG TERM...(Saturday night through Friday)
Issued at 313 PM CDT Fri Sep 22 2017
Saturday night...Do not really expect the cold front to advance
into our area until Sunday and thus the better rain chances will
continue to be confined to our far northwestern zones with little
change from Saturday afternoon into Saturday night.
Sunday...The cold front should start to make that push further
east and more into our western forecast area by afternoon and
evening. Most of the rain will come along and behind the cold
front. Expect rain will become more widespread and heavier across
our western zones, generally west of the Hastings/Grand Island
area. There could be a pretty good temperature contrast across our
forecast area with mid to upper 80s in Hebron and Beloit to
perhaps the 60s in Gothenburg.
Sunday night...The front moves into the heart of our forecast area
and this period currently is favored to be the wettest period for
most of our forecast area.
Monday...The cold front will pass to our east and the entire
forecast area will be cooler with highs in the 50s and lower 60s
over most of the area with a good deal of cloud cover and
continued rain. The best bet for rain will now shift into our
eastern zones. 3-day rain totals by the time it is all set and
done will range from 1-3 inches across most of the forecast area.
Tuesday through Friday...Cool and mainly dry with the cold front
now well off to our east.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday)
Issued at 712 PM CDT Fri Sep 22 2017
VFR conditions are expected to prevail. The cold front remains
off to the northwest of the forecast area and south to
southeasterly winds persist at both terminals. Winds are gusting
25 to 30 kts still and will continue until decreasing slightly
overnight. Cloud cover is expected to increase, but with high
clouds until later tomorrow afternoon/evening when mid-high clouds
move in. Southerly wind will again increase during the afternoon
hours Saturday.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
SHORT TERM...Wesely
LONG TERM...Wesely
AVIATION...Billings Wright
Area Forecast Discussion
National Weather Service Jacksonville FL
950 PM EDT Fri Sep 22 2017
.UPDATE...
Isolated to scattered convection primarily driven by afternoon
heating has now dissipated across much of the area. Only driver of
convection overnight will come from low level convergence along the
coastal areas...and current radar shows a few showers dotting the
coastal areas south of Jacksonville and the marine zones. This trend
is likely to continue...and will probably increase a bit toward the
early morning hours after about 2 AM, as convergence increases. In
addition...inverted low level trough noted in RAP guidance is
forecast to push inland over central FL and into srn portions of the
our area. This will usher in richer moisture and additional forcing
for increased shower activity for the southeast zones. Thus have
continued a trend of increasing rain chances again by sunrise on
Saturday morning. Have inserted some patchy fog over inland
southeast GA though probably not as much as what occurred Friday
morning. Lows still forecast around 70 well inland...and closer to
72-76 near the coast.
&&
.AVIATION...
Few-sct cumulus around 1500-3000 ft through tonight for coastal TAFs
though higher chance of sct-bkn cumulus at SGJ. VCSH still possible
through the night...with possible TEMPO SHRA for SGJ. Winds
northeast near 5 kt tonight...with near 8-12 kt at SSI and SGJ.
Winds increasing Saturday to 10-16 kt and gusts around 20-25 kt.
MVFR ceilings of 2000-3000 feet Saturday and good chance of showers
affecting terminals with VCTS possible...except more vicinity shower
activity at SSI.
&&
.MARINE...
Current forecast on track with winds of 10-15 kt...increasing to 15
kt/15-20 kt overnight. SCA continues for all waters. Only minor
edits for initial conditions appear needed at this time.
Rip Currents/High Surf:
Prior discussion...High risk will be needed for all area beaches
this weekend and early next week due to high surf and long period
swells from Maria. A high surf advisory will likely be required for
coastal locations beginning on Saturday for breakers in excess of 7
feet. Beach erosion will become an increasing concern during times
of high tide late this weekend and early next week.
&&
.PRELIMINARY POINT TEMPS/POPS...
AMG 70 87 69 87 / 10 40 0 10
SSI 75 84 74 83 / 20 30 10 10
JAX 72 85 73 85 / 20 50 20 20
SGJ 76 84 75 84 / 30 50 20 20
GNV 71 87 71 87 / 20 50 10 20
OCF 71 87 72 88 / 20 50 10 30
&&
.JAX WATCHES/WARNINGS/ADVISORIES...
FL...Coastal Flood Advisory until 10 PM EDT Saturday for Clay-Coastal
Duval-Flagler-Inland Duval-Putnam-St. Johns.
GA...None.
AM...Small Craft Advisory until 5 AM EDT Tuesday for Coastal waters
from Altamaha Sound to Fernandina Beach FL out 20 NM-
Coastal waters from Fernandina Beach to St. Augustine FL
out 20 NM-Coastal waters from St. Augustine to Flagler
Beach FL out 20 NM-Waters from Altamaha Sound GA to
Fernandina Beach FL from 20 to 60 NM-Waters from Fernandina
Beach to St. Augustine FL from 20 to 60 NM-Waters from St.
Augustine to Flagler Beach FL from 20 to 60 NM.
&&
$$
Shashy/Struble/Corless
Area Forecast Discussion
National Weather Service Marquette MI
757 PM EDT Fri Sep 22 2017
.SHORT TERM...(This evening through Saturday)
Issued at 343 PM EDT FRI SEP 22 2017
Short term forecast complicated by MCS moving through the Upper Mi
today. Latest radar imagery shows an intense line of strong to
severe storms moving into the east half of Upper Mi with generally a
weaker line of storms moving thru south central Upper Mi. Mixed
layer CAPE values up to 2000 j/kg combined with effective shear
values of 35-40 knots have supported isolated severe storms over the
west half of Upper Mi earlier today. Convection and more clouds than
expected have kept temps down cooler than forecast for many places
over the west half so made some necessary adjustments downward. It
will be tricky though if we see any partial clearing late afternoon
behind the MCS over the west as it would not take much mixing to tap
into much warmer air just off the sfc.
Tonight, better performing experimental HRRR model indicates any
remaining convection dissipating over eastern and south central
Upper Mi early this evening as air mass dries and becomes
increasingly capped by very warm 22-25c temps from 950-850 mb. With
models showing the mid-level ridge strengthening and the sfc-850 mb
warm front lifting north of Upper Mi, expect counties across Upper
Mi to be dry tonight. There may be some isolated convection along
the warm front over northern Lake Superior. Southerly gradient winds
between high pressure centered over the eastern CONUS and low
pressure and frontal system over MN will provide enough mixing to
preclude fog development over land areas. Dewpoints in the lower to
mid 60s however could support locally dense fog over marine
areas, especially given the recent rainfall from today`s MCS. Min
temps will stay well above normal given warm airmass and southerly
winds. Expect many record high minimum temps to be set today into
Saturday. Readings tonight will generally be in the upper 60s to
lower 70s.
Saturday, even with a strong subsidence inversion under the 590 DM
ridge over the region, forecast mixing to near 800 mb with temps
around 20C will support record to near record high temps in the
upper 80s and possibly lower 90s over much of the area except
downwind of Lake Michigan. Adding to the discomfort will be
dewpoints into the mid and upper 60s. Capping should be strong to
minimize shower/t-storm chances, per NAM/ECMWF/GEM keeping any
convection to the north and west. However, the frontal zone over
ne MN into western Lake Superior by late Saturday may allow some
showers/t-storms to sneak into the far west from IWD to CMX
toward evening.
.LONG TERM...(Saturday night through Friday)
Issued at 259 PM EDT FRI SEP 22 2017
Nam shows a deep 500 mb trough over the Rockies and a strong 500 mb
ridge over the ern U.S. 00z Sun. Upper air pattern changes very
little through 00z Tue with the ridge slowly moving east to New
England by 00z Tue. What this will mean is warm and humid conditions
will continue with summer like weather. Pops will remain mostly to
the north and west of the cwa with area in the warm sector for this
forecast period and some record highs are possible for this forecast
period.
In the extended, GFS and ECMWF show a 500 mb trough in the Rockies
and northern plains 12z Tue with a ridge over the ern U.S. 12z Tue.
This trough moves into the upper Great Lakes 12z Wed and this trough
remains into 12z Thu. Starting on Wed, a cold front moves through
and brings an end to the summer like temperatures with cooler air
moving into the area. Temperatures will go from above normal on Tue
to below normal for Wed through Fri.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 757 PM EDT FRI SEP 22 2017
VFR conditions are expected at all TAF sites. May see some fog near
or at KCMX and KSAW, but not expected at this time. LLWS will be a
factor at all sites through the night.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 343 PM EDT FRI SEP 22 2017
Low to mid 60s dewpoints sliding across Lake Superior are expected
to linger into early next week bringing patchy to areas of fog for
several days across the lake. Some of the fog could be locally dense
at times, especially tonight considering today`s rainfall over the
lake. Expect winds to generally be below 20 knots through the early
part of next week under a weak pressure gradient.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...07
AVIATION...Titus
MARINE...Voss
Area Forecast Discussion
National Weather Service Omaha/Valley NE
1101 PM CDT Fri Sep 22 2017
.SHORT TERM...(Tonight through Monday)
Issued at 310 PM CDT Fri Sep 22 2017
Precipitation chances, precipitation amounts and temperatures are
the main forecast concerns.
Water vapor satellite imagery in combination with recent RUC model
analysis showed a closed mid tropospheric low near the OR/ID/NV
border area, which was part of a large trough that stretched from
western Canada. A ridge extended from the eastern Great Lakes
region down into northern Mexico. 12 hour height falls at 500 mb
this morning were highest (around 60 meters) over northern AZ.
Winds at 300 mb were strongest (100 knots or higher) from northern
Baja CA up into WY. Thermal ridge at 700 mb (with temps as warm as
12 or 13 degrees C) extended from west TX into western and central
SD. A ribbon of higher 850 mb moisture, with winds at that level
mainly from 30 to 50 knots) was located just east of the mid
level thermal ridge. At the surface, a cold front extended from
low pressure over northeast SD down into southwest NE and
northeast CO. Temperatures east of the front in our area at 3 pm
were in the lower and mid 90s.
Tonight, will maintain some 20-30 percent chance of thunderstorms
in about the northwest half of northeast NE. There is a
conditional threat for severe storms, with damaging winds and
large hail. Chances are a bit higher prior to midnight. Southerly
flow across the area tonight should hold temperatures up, with low
expected to be mainly upper 60s and lower 70s. A few spots may
only drop to the mid 70s.
Frontal boundary will be nearly stationary near our northwest CWA
from Saturday through Saturday night, generally stretching from
southeast SD to southwest NE in that period. The chance for
showers and storms will be highest along and northwest of that
front. Temperatures ahead of the front should remain well above
normal, and went a bit higher than MOS for Saturday afternoon. For
Sunday, went mainly with highs of 85 to 90 ahead of the front and
70s behind the front. Precipitation should become likely Sunday in
the northwest part of northeast NE, then chances increase for the
rest of the area as the front slides to the southeast through
Monday. Expect at least some areas of locally heavy rain, but with
below normal rainfall recently, expect that if any flooding would
develop that it would be minor (at least for now).
Monday will be quite cool in northeast NE, with highs in the upper
50s to lower 60s, but ranging to 70s and lower 80s for the rest of
the area.
.LONG TERM...(Monday night through Friday)
Issued at 245 PM CDT Fri Sep 22 2017
The chance for showers and thunderstorms will remain high for
Monday night, but decrease on Tuesday from northwest to southeast.
That is based on current model timing, which could change.
At the start of this period, models are in good agreement that a
positively tilted trough at 500 mb should extend from Manitoba to
AZ. The northern end of that trough will trough to lift off to the
northeast, while a closed low forms back toward AZ Wednesday and a
ridge builds east from British Columbia. Right now, we will have a
mainly dry forecast from Tuesday night into Thursday, then carry
a low chance for showers around Thursday night.
Temperatures will start out below normal Tuesday, but moderate
back closer to normal by Thursday and Friday.
&&
.AVIATION...(For the 06Z TAFS through 06Z Saturday night)
Issued at 1100 PM CDT Fri Sep 22 2017
VFR conditions will continue through Saturday evening at all
eastern Nebraska TAF sites. Cold front is forecast to remain well
northwest of KOFK, allowing southerly winds near 15kt overnight,
and gusting to 25kt during the afternoon hours, at all sites.
Broken mid level clouds may move over KOFK, but only scattered
high clouds are expected at KLNK and KOMA through the TAF period.
&&
.CLIMATE...
Issued at 616 AM CDT Fri Sep 22 2017
The records for today and Saturday are:
Warm Max Warm Min Warm Max Warm Min
9/22 9/22 9/23 9/23
Omaha 99 (1937) 73 (2016) 96 (1892) 72 (1892)
Lincoln 99 (1937) 75 (1937) 97 (1921) 72 (1930,
1892)
Norfolk 96 (1940) 67 (2016, 92 (1921) 69 (1958,
1937) 1937)
&&
.OAX WATCHES/WARNINGS/ADVISORIES...
NE...None.
IA...None.
&&
$$
SHORT TERM...Miller
LONG TERM...Miller
AVIATION...Dergan
Area Forecast Discussion
National Weather Service Pueblo CO
728 PM MDT Fri Sep 22 2017
.UPDATE...
Issued at 707 PM MDT Fri Sep 22 2017
Updated grids to take down the Red Flag Warning at its natural
7 PM expiration time. There is still a slight chance for a
thunderstorm along the far eastern border...but latest HRRR runs
are keeping most of the convection just east of the area until
around midnight when a new round lifts northward into the area.
Meanwhile best chance for showers overnight will continue along
the Continental Divide with isolated to scattered showers
spreading northeastward into the Sangre De Cristos at times. Snow
levels will remain pretty high tonight...most likely above pass
levels...but a couple inches of sloppy wet snow will be possible
across the higher peaks.
Best chance for showers and thunderstorms across the plains will
spread in Saturday morning as energy lifts northeastward ahead of
the approaching upper trof. Soundings moisten up quickly Saturday
morning with scattered to widespread showers and a few embedded
thunderstorms forming across the plains. Main question for
tomorrow is how much will atmosphere destabilize across the
southeast plains during the afternoon. Mid level lapse rates are
not too impressive though depending on surface heating, there
could be an axis of higher CAPE east of a line from approximately
La Junta to Branson. Deep layer shear will be running around 40-50
kts...which is sufficient for rotating supercells. NAMNest
appears to develop some stronger convection across the far
southeast plains during the afternoon where atmosphere may
destabilize a bit better. Will have to watch how this evolves in
00z runs. Overall grids appear to be in good shape for now. -KT
&&
.SHORT TERM...(This evening through Saturday)
Issued at 251 PM MDT Fri Sep 22 2017
...Precip to return to most, if not all, of the region tomorrow...
Currently...
Breezy to windy over the area at 2 pm. Parts of the southeast plains
are gusting to 40 to 45 mph while most other lower elevations
regions are gusting to 25 to 35 mph. Red Flag conditions are
marginal at best as most areas have RH values in the 15 to 20%
range. Moisture in the midlevels is noted at mtn tops RH values are
quite high, above 70% (most of the higher San Juan mtn areas are 100%),
and quite a bit of mid lvl cloudiness is noted in teh water vapor
imagery. In addition, showers with isold thunder has been going
across the contdvd since earlier this morning. convective bubbles
were starting to develop over far se CO, and SPC mentioned one or
two stronger storms could form later this afternoon per latest
SWOMCD.
Rest of Today & Tonight...
Isolated thunderstorms will be possible over far southeast Colorado
this evening. As per latest discussion. one or two could be strong
to marginally severe. The best chance will be over Baca county as
best instability is located over this region. Later tonight showers
with isold thunder will slowly increase over the far SE Colo plains.
Showers with isold thunder will be possible this afternoon into
tonight across the San Juan mountains. This activity will also
increase at the night progresses. The best chance will be over the
San Juan mtns.
Over the rest of the area, it will remain primarily dry,
Tomorrow...
High amplitude 500 mb trough will continue to progress toward the
region and this system will likely bring a good chance of precip to
the area during this time period.
Guidance is pretty insistent on bring bands of rain with embedded
thunder across most if not all of the area during the day tomorrow.
Two areas of activity will be across the Contdvd region. The 2nd
area will be over the plains, with the overall best chance from
central/eastern Las Animas county NNE up to La Junta/Lamar regions. A
few strong storms could occur tomorrow as dwpts will be in the 50s
and CAPE values will roughly be in the 1000 J/KG range, with deep
shear about 30-40 knots. SPC currently does not have the area
outlooked, but I would not be too surprised if parts of the se CO
plains are outlooked in later SPC forecasts.
As for QPF, several areas on the plains may see 0.50 to 0.75 inches
of rain tomorrow.
Snow will be likely across the higher elevations, with the
accumulating snow mainly above 11000 feet. 1 to 4 inches of new snow
will be possible at the highest elevations. Areas along the contdvd
will have the best chance of snow.
Temps tomorrow will be noticeably cooler than today, with highs
mainly in the m60s to m70s plains, and 50s and 60s valleys. Breezy
southerly winds will occur, especially over the far se plains and
mtns and valleys.
.LONG TERM...(Saturday night through Friday)
Issued at 251 PM MDT Fri Sep 22 2017
Active and cooler weather is expected into early next week. Models
are having a hard time through the middle of next week and there
is a high degree of run to run inconsistency leading to lower
forecast confidence. Ensembles spreads are high as well also
leading to lower confidence in the later half of the extended
period.
Saturday night...the upper level low sitting over Utah will
continue to lift energy northeast across Colorado Saturday night.
Strong to severe weather will be ongoing across the far Eastern
Plains and should push east into Kansas by midnight. Large hail,
gusty winds in excess of 60 mph and heavy rainfall will be
possible. For the rest of the area, showers and thunderstorms will
be continuing over the mountains, spreading east into the Eastern
Plains through the evening hours. Snow levels will lower some
through the overnight hours down to around 10 kft, especially
along the Continental Divide where a couple inches of snow are
possible on area peaks.
Sunday...currently this is where the most change looks to have
occurred in the forecast. Models have the upper level low starting
to track eastward into western Colorado through the afternoon. The
current model runs bring dry air north out of New Mexico and dry
slot southern Colorado. This has mixed the dryline further east,
over western Kansas and would bring our severe weather risk down
to zero through Sunday evening. This would also mean drier
conditions across much of the region, with the exception of the
mountain areas, where near continuous showers and thunderstorms
are expected into Sunday night. Warmer afternoon highs are also
expected with mid to upper 70s across the Plains. Low pressure is
forecast to develop near Pueblo by Sunday afternoon, and move east
to near Lamar overnight. This will send a cold front south across
the CWA by Monday morning. A few model solutions to develop light
precipitation across the Plains with the front late Sunday night.
Snow levels over the mountains will also fall to around 9 kft with
a few more inches of snow possible above that elevations.
Monday and Tuesday...the upper low is forecast to split, with
energy moving into the Northern Plains, and energy moving into
Arizona. This will keep southern Colorado under cool conditions
into early next week. Temperatures will be in the lower to mid
60s across the Plains. As far as precipitation, much will depend
on energy moving across moving around the upper troughs.
Southeasterly upslope flow across the region would favor the
Eastern Mountains, into the I-25 corridor. But this time period is
where uncertainty in the model solutions begins to develop.
Wednesday through Friday...big model differences through the mid
to late week period. The GFS keeps the split trough as such, with
a longwave trough over the Northern Plains, and weak troughing
over the Desert Southwest. Several disturbances would be forecast
to lift north out of New Mexico and produce rounds of
precipitation for the region. The ECMWF has the longwave trough to
the north, but drops a strengthening disturbance south into the
Great Basin through the end of the week. It has much better
chances for precipitation, along with much cooler temperatures
through the back half of the extended period than the GFS. Mozley
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 251 PM MDT Fri Sep 22 2017
VFR conditions likely tonight for all of the TAF sites (KPUB, KALS
and KCOS). Gusty winds this afternoon will weaken by early to mid
evening.
For tomorrow, cigs will lower with a good chance or precipitation
developing at all of the 3 taf sites by late morning or early
afternoon. Some embedded thunder will also be possible. MVFR
conditions will be possible due to low cigs, especially at KCOS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...KT
SHORT TERM...HODANISH
LONG TERM...MOZLEY
AVIATION...HODANISH
Area Forecast Discussion
National Weather Service Shreveport LA
1007 PM CDT Fri Sep 22 2017
.DISCUSSION...
Convection has diminished entirely this evening with mostly clear
skies across the region. Falling temperatures are already nearing
dew points at some sites south of I-20 so have expanded patchy fog
coverage into much of north central Louisiana after midnight with
more extensive coverage farther north of I-20 toward daybreak. The
remainder of the forecast in on track for tonight with temperature
trends in good shape. No other changes are needed at this time.
Updated text products will be out shortly.
/19/
&&
.PREV DISCUSSION... /issued 641 PM CDT Fri Sep 22 2017/
AVIATION...
Isolated showers have dissipated across portions of North Central/
Northeast Louisiana with VFR conditions expected to prevail
through the evening hours. Conditions should begin deteriorating
in the form of patchy dense fog and IFR/LIFR ceilings across area
terminals after midnight through the mid morning hours on Sat. The
worst fog potential will likely be across the MLU/LFK/GGG
terminals with low ceilings likely at those terminal in addition
to the TYR terminal. Otherwise, IFR/MVFR ceilings will be possible
shortly after sunrise at the remaining terminal locations for at
least a couple hours through mid morning before ceilings scatter
out and fog lifts areawide on Saturday by mid to late morning. VFR
conditions should prevail beyond 17z on Sat through the afternoon
hours.
13
PREV DISCUSSION... /issued 314 PM CDT Fri Sep 22 2017/
DISCUSSION...
An UA ridge draped from the Great Lakes region southwest to
across the majority of the Four-State Region has led to sea-breeze
convection having a tough time making it to the region /versus
what we have seen the last several days/. Only a few isolated
showers were nearing/moving across Deep east Texas late this
afternoon. However, a weak shear axis on the eastern periphery of
the aforementioned UA ridge have aided in developing isolated
showers across northeast LA and southwest AR, nearing Monroe LA
and Texarkana AR respectively. Per radar analysis, the precip
activity across all locations were not strong at all /which is not
surprising given lack of UL support/ and per the HRRR solution,
will diminish shortly after sunset. Furthermore, 21Z metars
reported temps in the lower 90s, making it unseasonably warm for
the first day of the Fall season. Tonight, clear skies, light
southerly winds and moist sfc conditions /dewpoints in the 60s
and 70s/ will result in another round of patchy fog mainly along
and south of the Interstate-20 corridor. Portions of east TX and
deep east TX may once again experience patchy dense fog, though
confidence is not high enough to issue a Dense Fog Advisory attm.
Will let later shifts see if dense fog comes into fruition.
Slightly better chances for isolated to scattered showers and
thunderstorms will occur this weekend, courtesy of a westward
drifting weak UA disturbance, originating from the southeast
CONUS. This disturbance providing for a bit of UL support will
interact with a relatively moist low level atmosphere as southerly
sfc winds ensue /PWATs on the order of 1-1.50 inches/. Attm, do
not expect storms to reach strong levels given the that the
disturbance is not overly strong by any means. This general
weakness will remain nearby through Monday, before commencing to
shift east and wane significantly by Tuesday.
The eastward shift of the aforementioned weak disturbance is due to
a longwave UA trough translating east across the Rockies. Long term
solution hint at the longwave trough breaking into two defined
pieces: the northern periphery ejecting quickly northeast to across
the Northern Plains and into Canada by mid-week, whilst the southern
periphery progresses much slower eastward across the Desert
southwest/New Mexico Boot heel by late week. With a cold front
expected to impact the Four-State Region from northwest to
southeast on Wednesday, combined with a slow eastward propagation
disturbance to our west, will result in much better chances for
wetting rains initially across the northwest zones, then spreading
to the remainder of the area throughout the week. This welcomed
pattern change will result in daytime temps dropping from the
lower 90s down into the 70s and 80s, with overnight temps cooling
into the 50s and 60s by late week.
29
&&
.PRELIMINARY POINT TEMPS/POPS...
SHV 73 94 73 92 / 10 20 10 20
MLU 71 93 71 91 / 10 20 10 20
DEQ 69 92 69 91 / 0 10 10 20
TXK 71 92 71 91 / 10 10 10 20
ELD 70 92 70 90 / 10 20 10 20
TYR 72 92 71 92 / 10 20 10 10
GGG 71 93 70 92 / 10 20 10 20
LFK 71 93 71 92 / 10 20 10 20
&&
.SHV WATCHES/WARNINGS/ADVISORIES...
AR...None.
LA...None.
OK...None.
TX...None.
&&
$$
19/13/29