Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/17/18
Area Forecast Discussion...UPDATED
National Weather Service Cheyenne WY
653 PM MDT Tue Oct 16 2018
.SHORT TERM...(This evening through Wednesday)
Issued at 158 PM MDT Tue Oct 16 2018
Chamber of Commerce afternoon shaping up with surface ridge of high
pressure and light winds. Temperatures were in the 40s and 50s. VIS
satellite showed a few cirrus clouds spreading southward.
Northwesterly flow aloft will back to southwesterly as a upper low
over the southwest CONUS drifts northward and gradually weakens.
Models keep any moisture with this system to our south, resulting in
a dry forecast. Temperatures will moderate to seasonal normals.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 158 PM MDT Tue Oct 16 2018
Weakening upper low over the central Rockies will be overtaken by
progressive upper trough moving into the northern/central Plains
Friday. A northwest-southeast oriented upper ridge will dominate the
Rockies and Plains into early next week. Above average temperatures
and dry conditions will continue.
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 615 PM MDT Tue Oct 16 2018
minimal aviation impacts as VFR will prevail through the next 24
hours across the region. On caveat to monitor for would be patchy
fog across the Nebraska Panhandle from 10-14Z. GFS and HRRR
indicate high enough dewpoint depression spreads that would
preclude fog development but the NAM has lower spreads that could
support some patchy fog development. Will monitor trends for 06Z
TAFs and if fog wording needs to be incorporated.
Winds will be light and variable through the overnight and then
become more steady from the southwest and south through Wednesday.
Issued at 158 PM MDT Tue Oct 16 2018
Mild temperatures and light winds will limit fire potential
through the period. Melting snow pack will help to keep humidity
high and temperatures below normal.
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
949 PM CDT Tue Oct 16 2018
Quick update to account for latest radar trends. Weak isentropic
ascent persisting across the area will result in periods of light
drizzle or rain overnight with accumulations across the Hill Country
expected to remain under one quarter inch. RAP analysis shows smaller
disturbances lifting out of Mexico and into the Rio Grande Plains
after midnight tonight in the south-southwest flow aloft that may
help generate heavier shower activity across portions of Val Verde
and Edwards, but expect this to remain west of the majority of the
area. Not planning on any changes to the ongoing Flash Flood Watch
In between drizzle/rain tonight, patchy fog development will be
possible as the relaxing surface pressure gradient as resulted in
light winds. Already seeing this development in the Hill Country and
will have to monitor for expansion to the I-35 corridor and into the
coastal plains. Otherwise, expect another chilly night with lows in
the 40s to low 50s.
.PREV DISCUSSION... /ISSUED 725 PM CDT Tue Oct 16 2018/
MVFR conditions are expected this evening as the strong post frontal
inversion lingers across South Central Texas with ceilings lowering
to IFR along the I-35 corridor overnight and rising back to MVFR by
mid-morning Wednesday. Lingering isentropic ascent may be able to
produce some light drizzle or rain at all terminals through the
period with high resolution guidance indicating the best window for
AUS/SAT/SSF overnight and DRT after 14-15Z Wednesday. Expect
northerly winds to persist in the 10-15 knot range.
PREV DISCUSSION... /ISSUED 418 PM CDT Tue Oct 16 2018/
SHORT TERM (Tonight through Wednesday Night)...
Afternoon radar imagery shows persistent rain continuing across
portions of the I-35 corridor, Hill Country and southern Edwards
Plateau. Hourly amounts according to radar and gauge data have been
trending downward this afternoon across the Hill Country and I-35
corridor. However, any additional rainfall falling on saturated
ground will instantly result in runoff.
The latest round of hi-res models suggest the better chance for
precipitation will contract and shift slightly northward this evening
and overnight. This should place the higher rainfall chances along
and north of a Del Rio to Fredericksburg to Burnet line. With models
showing the stronger lift focused along the Rio Grande and southern
Edwards Plateau, we should see the higher rainfall totals through
tonight across Val Verde and Edwards county. However, as mentioned
above, any additional rainfall over the Hill Country into west
central Texas will result in runoff.
On Wednesday, we should see a slight decrease in rainfall chances
across most of the region as the mid-level ridge of high pressure
builds westward across the northern Gulf of Mexico. The exception
will be across portions of the Rio Grande plains and southern Edwards
Plateau where mid-level shortwave activity will move northward from
Coahuila Mexico into the above mentioned areas.
Beginning Wednesday night, an area of higher moisture will begin to
work northward from the western Gulf of Mexico into south Texas. The
latest satellite precipitable water product shows values near 2.5" in
the western Gulf.
LONG TERM (Thursday through Tuesday)...
The above mentioned surge of moisture from the Gulf of Mexico will
continue to spread northward into south central Texas on Thursday.
Models suggest precipitable water values will increase to near 2"
across most of the region. We continue to see a good signal for
rainfall in the model output and have opted to push rain chances much
higher in the forecast for Thursday. Based on the ongoing flooding,
along with another surge of moisture headed our way, we have opted to
extend the Flash Flood Watch through early Thursday evening. If later
model data remains consistent, we will likely have to expand the
coverage of the watch to include counties along the I-35 corridor.
For now, we will forecast an additional 1 to 2 inches with isolated
totals near 4 inches across the watch area.
The active weather pattern is likely to continue Friday and possibly
well into Saturday as another cold front is expected to move in from
the north. We will continue to mention rain chances in the forecast
into early next week, with the better focus likely to remain out west
along the Rio Grande.
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 47 54 51 57 52 / 50 40 50 70 70
Austin Bergstrom Intl Airport 50 55 51 57 52 / 40 40 50 70 60
New Braunfels Muni Airport 47 55 51 58 53 / 30 40 60 70 70
Burnet Muni Airport 44 51 48 56 52 / 70 50 40 90 70
Del Rio Intl Airport 44 54 49 57 52 / 70 70 60 60 50
Georgetown Muni Airport 48 53 51 57 52 / 50 40 40 70 70
Hondo Muni Airport 49 57 52 59 54 / 50 50 70 100 80
San Marcos Muni Airport 48 55 51 57 53 / 40 40 60 70 70
La Grange - Fayette Regional 51 58 53 61 56 / 30 40 40 60 50
San Antonio Intl Airport 47 55 51 58 53 / 40 40 70 90 70
Stinson Muni Airport 49 56 52 59 54 / 30 40 70 90 70
Flash Flood Watch through Thursday evening for Bandera-Blanco-
Area Forecast Discussion
National Weather Service Gray ME
1031 PM EDT Tue Oct 16 2018
After a brief break tonight...the second in a series of strong
cold fronts will arrive on Wednesday with another round of
showers and gusty winds with the coldest air of the fall season
arriving Wednesday night and Thursday with mountain snow showers
continuing. High pressure arrives late Thursday and Thursday
night with slackening winds and moderating temperatures through
the end of the week. The next chance for rain showers will come
Saturday ahead of another frontal system.
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Have updated the forecast based on current observations and
latest mesoscale models. Chilly conditions will continue this
evening with a window of radiation cooling continuing through
about midnight over southern and central sections. In the north,
clouds will continue to spill into the region shortly.
Have dropped overnight low temperature forecast with many
interior areas falling near or below the freezing mark. The
increase in late night clouds may allow temperatures to climb
later tonight. Lastly, the latest HRRR continues to bring the
possibility of very light precipitation to northern areas after
07Z, some of this being snow shower activity over northern
High Impact Weather Potential: Minimal.
Pattern: Active pattern across the eastern United States early this
afternoon with a sprawling longwave trough taking up residence over
the eastern two thirds of NOAM with a longwave ridge centered along
the west coast. For the time being...the NAO remains positive...so
despite the depth of this trough...it will pull east through the
near and short term forecast period. Within this trough are two
significant shortwaves. The first is now departing the region to
the east while the second will arrive on Wednesday. Thus...
through the near term forecast period we find ourselves between
these two features with a weak surface ridge axis building in
from the west with a generally quiet night expected.
Through this evening: Winds will continue to diminish to less than
10 mph this evening with temperatures falling fairly rapidly in the
dry airmass under mostly clear skies...with most spots in the
upper 30s/lower 40s by 8pm.
Tonight: Ridge axis overhead this evening quickly moves east with
flow beginning to back ahead of upstream shortwave that will dive
into the Great Lakes through daybreak. Top down saturation will
commence during the overnight hours with cloudiness gradually
thickening and lowering. At the leading edge of a modest H8
Theta-E surge...recent high resolution HRRR runs have suggested
a blossoming area of very light precipitation in the 9-12Z
timeframe...with some support from the NAM nest and High res ARW
window run. While it would be light...could see some snow in
the mountains...with any precipitation to the south likely
falling as light rain. Temperatures will fall quickly this
evening...then level off and likely begin rising a bit overnight
with lows in the 30s in all areas except southeastern NH and
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
High Impact Weather Potential: Strengthening westerly winds
Wednesday followed by accumulating snow in the mountains and
favored upslope regions to the north Wednesday night.
Pattern: Secondary shortwave arrives during the short term period
with another northern stream...relatively moisture-starved cold
front arriving during the day Wednesday followed by strong cold
advection which will usher in the coldest air of the fall
season thus far. Forecast concerns center largely on winds given
the strength of this system...with attention paid to
precipitation chances as well...particularly in the mountains
where the pattern looks favorable for upslope snow showers.
Wednesday: PWATs ahead of arriving secondary front are fairly
meager /0.5-0.6 inch/...but more impressive will be
along/immediately behind the front as 1000-700 mb lapse rates
steepen with 50-100 J/kg of CAPE...cyclonic flow and support at
the jet level likely supporting a convective line of showers
that decays as it moves off the mountains and towards the
coastal plain. In these situations...you can occasionally bring
graupel to the surface given the cool airmass...however...wet
bulb zero heights are still 3-5kft so this looks like it will be
more of an exception than the rule. It will be a different
story in the mountains where precipitation will increasingly
become frozen towards evening with some light accumulations at
elevation. Highs will reach the 50s along the coast and
foothills...with 40s in the mountains. Temps in all areas will
fall in the afternoon.
Wind: Westerly winds strengthen ahead of the approaching front
with a surge of cold advection immediately behind the front
/combined with good mixing from lapse rates mentioned above/
potentially conspiring to bring 30-35 mph winds to the surface
for a short time /~2 hr/ immediately after frontal passage.
Wednesday Night: Robust cold advection continues through the
night with strong cyclonic flow and residual low level moisture
allowing upslope snow showers to continue in the mountains.
Lift/moisture actually reach into the DGZ as temps fall
overnight...so expect snow showers to increasingly be able to
accumulate overnight /as mentioned by previous forecaster/. Have
painted 1-2 inches over the terrain and in northern Coos and
far northern Oxford and Franklin counties. Further south...
expect a few sprinkles/flurries in the evening...but overnight
activity will increasingly be confined to the mountains /in line
with froude number diagnostics/ as moisture thins and flow
loses it/s cyclonic nature.
Winds: Stronger winds will hold off until daytime mixing
resumes on Thursday but 10-15 mph winds with gusts to around 25
mph will continue through the overnight.
Temps: T8s fall below -10C /-3 sigma/ under strong cold
advection...and despite mixing will push all areas into the 20s
and 30s. Still have a few active zones from a frost/freeze
perspective and while a frost is not likely given the winds...a
hard freeze is not out of the question for these remaining
.LONG TERM /THURSDAY THROUGH TUESDAY/...
A big push of cold air moves into the region on Thursday.
Temperatures aloft drop to well below normal with 700mb temps of
-20C near record cold for this time of year. Accompanying the
cold air will be a strong pressure gradient driving gusty
Winds will begin to increase in the early morning hours of Thursday
and continue through Thursday afternoon; a wind advisory will likely
be needed with more scattered power outages possible. Strongest
winds will be through the morning hours on Thursday when the
mixing begins to allow the higher wind speeds to reach the
surface and the strongest pressure gradient occurs. Have
increased gusts a bit through this narrow time window with a
few gusts to 40kts possible and widespread 25-5kt gusts across
the lower elevations and the summits correspondingly higher.
As the colder air moves into the region high temperatures on
Thursday will hold in the 40s to upper 30s, nearly 15 degrees below
normal. While the core of the cold air aloft will begin to shift
northeastwards on Thursday night the decreasing pressure gradient
will allow the winds to decouple by daybreak opening us up for good
radiational cooling in the mountain valleys. While it may take
until well after midnight to loose the winds, when we do
temperatures will drop rapidly and thus have pushed lows a bit
colder than much of the guidance. Even with a slight breeze this
airmass will be enough to end the growing season for the
remaining portion of the area and a Freeze warning will likely
be needed for the coast.
Friday temperature will moderate slightly as the cold air moves out
of the region, with good agreement amongst various guidance stuck
close to the consensus.
For the weekend the next chance of precipitation moves into the
area. It`s increasingly looking like the northern and southern
stream will not phase allowing a weak disturbance to pass south of
us early in the day on Saturday with a northern stream shortwave
impacting the mountains through the weekend. Will see scattered
showers across the entire region with highest PoP in the mountains.
With temperatures marginal for snow, expect mainly rain for all but
the highest elevations during the day with a transition to some
light snow above 2000ft overnight Saturday into Sunday.
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
Summary: High pressure builds into the region tonight with a
fast moving cold front arriving Wednesday afternoon...and moving
south of the region Wednesday night.
Restrictions: Expect VFR conditions to continue through Wednesday
night. Could see some isolated restrictions in SHRA late Wednesday
at HIE/LEB...and possibly AUG...but not likely south and east of
Winds: Northwesterly winds will continue to gradually weaken through
this evening and tonight as high pressure arrives from the west. On
Wednesday...westerly winds strengthen to 15G25kts ahead of the cold
front before shifting northwesterly Wednesday night and continuing
15G25kts through the night.
LLWS: No LLWS expected through the period as the low levels remain
well-mixed given the strong wind field.
Lightning: No lightning expected through Wednesday night.
Long Term...VFR conditions will continue through most of the
extended. Strong cold advection will bring gusty northwesterly
winds for Wednesday night into Thursday morning. Another system
will bring a chance for showers to the entire area on Saturday
with highest Pop in the mountains where MVFR and overnight snow
showers are likely on Saturday night.
Short Term...Winds/waves have subsided a bit from this
morning...but SCA conditions will continue outside the bays
through tonight before waves strengthen ahead of our next system
late Wednesday with a Gale watch issued beginning late Wednesday
and continuing into the long term forecast period below.
Long Term...Cold air will move into the region overnight Wednesday into
Thursday. The cold air and tight pressure gradient will result in
strong northwesterly winds with gusts to Gale and a Gale Watch has
been issued. Winds will decrease as high pressure builds in on
Friday before again increasing to gusting 25-30kts will SCA likely
KGYX radar outage with parts on order this afternoon. Expect to
be back up around midday Thursday.
MARINE...Gale Watch from Wednesday evening through Thursday afternoon
Area Forecast Discussion
National Weather Service Miami FL
803 PM EDT Tue Oct 16 2018
Showers continue to push ashore from the Atlantic and that
activity is expected to continue overnight into the morning.
Convective coverage should shift as the day goes on inland and to
the west towards APF by afternoon. Easterly flow with some gusts
to 20 kts can be expected again.
.PREV DISCUSSION... /issued 754 PM EDT Tue Oct 16 2018/
Current radar shows isolated shower activity along the Atlantic
coast moving quickly westward due to persistent easterly flow.
The latest observations indicate around 10 mph along the Atlantic
beaches. The HRRR and the WRF prog an increase in shower coverage
over Miami- Dade and Broward counties during the next several
hours. Thus, have increased PoPs in the latest update to reflect
chance of showers and slight chance of thunderstorm in this
general area overnight. Otherwise, all other variables appeared on
PREV DISCUSSION... /issued 416 PM EDT Tue Oct 16 2018/
Latest WPC analysis depicts an elongated 1022 mb surface high
stretching from the mid-Atlantic to near Bermuda. A stationary
front can also be noted from the Carolinas down towards the
western Gulf. Clockwise motion around the aforementioned high has
allowed for persistent breezy easterly flow across Southern
Florida. Observed winds speeds this afternoon have generally been
sustained 10 to 15 mph, gusting occasionally to 20 mph. This flow
regime has led to the highest maximum temperatures to develop
along the western interior, in the low 90s. Mainly upper 80s have
been reported along the east coast where the greatest influence
from the Atlantic waters exist. Satellite derived PWAT indicates
relatively dry air, with values only around 1.6". Showers have
been far and in between today as mostly dry conditions have
prevailed. Tonight, small scale models including the HRRR and Hi-
Res WRF show shower development, mainly over coastal areas of
Miami-Dade and Broward counties as a weak impulse of enhanced
moisture moves over the area from the Bahamas. Minimum
temperatures will range from near 80 degrees along the east coast
metro to mid 70s along the Gulf coast. These values are around 3
to 5 degrees above normal for this time of year.
Wednesday through this weekend: Both the GFS and ECMWF prog a
robust cell of high pressure to migrate west from its current
position and meander over the the Florida peninsula through at
least Friday. This will again lead to deep layer easterly flow,
partly cloudy skies, and mainly dry conditions. Temperatures are
generally forecast in the upper 80s along the east coast metro and
low 90s inland and near the Gulf coast. Record temperatures may
be just a few degrees shy of being tied, esepcailly on Wednesday,
at Naples and West Palm Beach. Long range models begin to drop a
low pressure trough down by this weekend into early next week.
Though it may not make it all the way to our CWA, increasing
moisture and instability ahead of the front will at least help to
enhance our precipitation chances as it nears.
High pressure centered east of the waters will continue to
provide moderate easterly wind through the week, with Atlantic
winds occasionally increasing to around Small Craft Advisory
levels, especially mid to late week. Seas will be 4 feet or less.
Aside from isolated passing showers, mainly in the Atlantic, dry
weather will prevail.
A high risk for rip currents will likely develop early Wednesday
through the rest of the week for the Atlantic beaches due to
persistent easterly winds. Swimmers should exercise extreme
caution given these expected conditions.
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 78 89 77 88 / 20 20 20 20
Fort Lauderdale 80 88 80 87 / 30 20 20 20
Miami 78 89 78 88 / 30 20 20 20
Naples 75 91 74 90 / 10 30 10 10