Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/21/20
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
757 PM CST Thu Feb 20 2020
.UPDATE... /LESS CLOUDS, WARMER MINS HILL COUNTRY/
MOS guidance trends, and the last several runs of the HRRR suggest
temps over northern counties may have a tougher time falling to the
freezing mark tonight. This is despite a more agressive clearing
trend in the skies to the north this evening. The influences on min
temps in the model data is likely responding to soil saturation and
slightly higher winds through the night. Impacts on the forecast are
subtle, with upward min temp adjustments made by only a degree or
two. Given that we are late in the season for freezing temps, felt
the subtle evening update was worthwhile.
.PREV DISCUSSION... /ISSUED 548 PM CST Thu Feb 20 2020/
With the end of precipitation having occurred at all TAF sites and
early evening gusty winds of 15 to 30 knots, slowly improving
ceilings will reach AUS any time now, and should reach the SAT/SSF
areas by around 03Z or 04Z. Winds should drop much of the extra gusts
by this time and light N/NEly winds mainly below 12 knots are
expected for daytime Friday. VFR level stratus should continue well
into daytime Friday over the Rio Grande Plains and DRT while
occasional cigs of around 10 KFT or higher will linger over the SAT
area. AUS should see a mostly sunny sky for most of Friday.
PREV DISCUSSION... /ISSUED 218 PM CST Thu Feb 20 2020/
SHORT TERM (Tonight through Friday Night)...
Gusty north winds will continue through the mid-evening hours across
south central Texas. Wind gusts will tend to ease after sunset, but
northerly winds and generally overcast skies will continue. We could
see some decrease in cloud cover after midnight into early Friday
morning for areas generally along and north of a Llano to La Grange
line. Overnight lows will range from near freezing in the Hill
Country and southern Edwards Plateau to the lower 40s along the Rio
Grande and into the coastal plains. Northeast winds continue for
most areas tomorrow. The exception being along the Rio Grande
tomorrow afternoon, where winds will transition to a more
southeasterly direction. Below normal temperatures continue on
Friday with highs generally in the 50s. We do expect some clearing
of skies tomorrow for the Hill Country and areas generally along and
east of the I-35 corridor. Cloudy skies will likely remain intact
farther west along the Rio Grande and southern Edwards Plateau.
Below normal temperatures continue for Friday night with lows near
freezing in the Hill Country to the lower 40s along the Rio Grande.
LONG TERM (Saturday through Thursday)...
Saturday will be slightly warmer than Friday, with highs in the low
60s. By Saturday night, winds turn back out of the southeast and
increase moisture. These southeasterly winds keep the overnight lows
for Saturday night and Sunday morning mild in the mid 40s to low 50s.
Meanwhile, an upper from the northwest moves into the Plains Sunday.
This upper low drags a cold front across the area Monday with little
to no effect on temperatures. Models still showing a mostly dry
passage with only slight chances for showers along the Coastal
Plains. By Tuesday, another cold front crosses the area bringing a
cooler airmass. High temperatures respond by dropping into the low
60s for both Wednesday and Thursday, with a very chilly Wednesday
night and Thursday morning, with freezing temperatures in the Hill
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 35 53 37 60 47 / 0 0 0 0 0
Austin Bergstrom Intl Airport 36 53 35 61 46 / 0 0 0 0 0
New Braunfels Muni Airport 37 54 36 61 48 / 0 0 0 0 0
Burnet Muni Airport 33 50 35 58 45 / 0 0 0 0 0
Del Rio Intl Airport 41 57 42 66 50 / 10 0 0 0 0
Georgetown Muni Airport 34 51 35 58 45 / 0 0 0 0 0
Hondo Muni Airport 37 56 37 64 48 / 0 0 0 0 0
San Marcos Muni Airport 36 53 35 61 46 / 0 0 0 0 0
La Grange - Fayette Regional 38 54 35 61 47 / - 0 0 0 0
San Antonio Intl Airport 37 55 39 61 50 / 0 0 0 0 -
Stinson Muni Airport 39 55 39 63 50 / 0 0 0 0 -
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
945 PM EST Thu Feb 20 2020
Low pressure off of the southeast coast will deepen and lift
northeast well offshore tonight and Friday. Cold high pressure
will rebuild over the area for the weekend, before another area
of low pressure impacts the area early to mid next week.
.NEAR TERM /Rest of Tonight/...
As of 945 PM Thu...Main change was to lower snow amounts a bit,
but forecast remains the same with warning criteria snow
expected in the WSW. RA/SN line slowly sinking south of a
Kenansville to New Bern to Swan Quarter line per Dual Pol radar
analysis. Sfc temps even where it is snowing are slow to drop to
below freezing, so snow is not accumulting all that rapidly
despite moderate rates. Have mentioned 3-5 inch accums where WSW
is in effect, and a trace to around an inch closer to the coast
where temps will be warmer in the WSY.
Prev discussion... As of 710 PM Thu...Update to add Duplin
county to WSW, as mesoscale banding of heavy snow forecast to
affect much of the county, with totals reaching 2 to 4 inches.
Fcst mainly on track, and only tweaked to transition to snow
earlier, as column has cooled to below freezing for most of the
nrn coastal plain counties, and will transition from a wintry
mix to mostly snow from west to east from there.
Prev discussion... As of 400 PM Thu...Precip shield has
encompassed much of the CWA with a few scattered reports of
sleet along the Hwy 264 corridor. Mesoanalysis continues to show
a bullseye area for frontogenesis parked over that area. The
deformation zone will work to concentrate areas of the heaviest
precip throughout the event. The HRRR is initializing well,
showing the deformation zone with the associated concentrated
precip area over the northern counties and pivoting overnight to
a more north-south orientation, likely positioning itself along
Hwy 17. Highest snow amounts will likely occur north of Hwy 70
with 4-6 inches. Southern counties will still see some
accumulations of 2-4 inches and less than 2 inches along the
As the event unfolds, we expect rain to begin changing over to
mixed precip late afternoon/early evening NW along the Hwy 264
corridor, spreading SE to N. Craven, N. Onslow, and S. Beaufort
counties by 03z. The transition time from rain to snow is
expected to take place rather gradually, threatening a few
hours of robust wintry mix that may cause hazardous travel. Snow
will then begin taking over in our NW counties and pushing SE
through midnight, afterward which snow will become the dominant
ptype along Hwy 17 and west. Snowfall rates are expected to be
relatively high, up to 0.5"/hr in and around the deformation
zone, which will provide a moderate dendrite growth zone for a
few hours. Snow will likely be heavy and wet when it reaches the
surface, creating concerns for power outages, reduced
visibilities, and slippery roads, particularly within mesoscale
bands. As the coastal low moves out to sea, we can see snowfall
beginning to taper off NW around 10-12z, eventually clearing
out of much of the forecast area by 15z, with any lingering
precip SE being predominantly rain.
.SHORT TERM /FRIDAY/...
As of 300 PM Thurs... Behind this system Friday skies will
clear from west to east, but strong winds will continue. Strong
CAA and snow cover will limit surface heating, and temperatures
will struggle to reach past the upper 30s, with wind chills in
the 20s all day.
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
As of 300 PM Thu...Fri night through Sunday...High pres will
build in Fri night thru the weekend with dry weather. With
expected snow pack and clear skies Fri night expect very cold
temps with the normally colder inland areas dropping to around
20. Beaches will be a bit milder with upr 20s to lower 30s.
Temps remain cold Sat with highs in the 40s to around 50 with
plentiful sunshine. Temps moderate on Sunday as the high builds
overhead and hgts aloft increase. Highs shld reach the upr 50s
to lower 60s most spots.
Mon through Wednesday...Looks mild and unsettled this period as
a complex frontal system approaches Mon and slowly pushes thru
Tue night into Wed before dissipating. Plenty of moisture will
spread N in advance of the front with likely pops Mon/Mon night
and chc Tue and Wed. The front should cross the coast and
dissipate Wed. Highs Mon will be mainly in the lower 60s with
mid/upr 60s Tue and Wed.
Late next week. High pressure will build into the area behind
the front with cooler highs in the 50s Thursday.
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
Short Term /through Friday morning/...
As of 7 PM Thu...Coastal low continues to strengthen this
afternoon. Cigs have mainly dropped to IFR as change over to a
wintry mix, bringing with it IFR conditions. Tonight into the
overnight hours, precip will transition to all snow beginning NW
and pushing SE, dropping visibilities down to 1 mile, or
potentially less. Ceilings and visibilities will improve once
the snow tapers off W to E Friday morning. Strong NNE winds will
persist throughout the TAF period.
Long Term /Fri night Through Tuesday/...
As of 300 PM Thu...VFR conditions expected to prevail through
the weekend as high pres builds across. Shra threat increases
Mon and Tue ahead of approaching cold front with occasional sub
Short Term /Tonight and Friday/...
As of 300 PM Thu...Dangerous boating expected through Fri as
strong NNE winds develop today and cont tonight as low pres
develops and deepens well to the SE. Cont Gale Warning for all
but Pamlico River where we have SCA. Winds will increase to 30
to 40 kt with gusts to 45-50 kt over the warmer water tonight
into Friday. These winds will lead to seas reaching to 9 to 14
ft tonight into Fri.
Long Term /Fri night through Tue/...
As of 300 PM Thu...Winds will slowly begin to decrease early
Fri evening to sub Gale and especially Fri night to below 25 kt
late as the low moves further offshore. Seas will remain
dangerous early 8-14 ft subsiding to 5-9 ft early Sat. Winds
become light Sat as the high builds close with seas subsiding to
4 to 6 ft late. Light winds cont Sunday with the high
overhead...seas finally drop below SCA lvls Sun at 3 to 5 ft.
The high moves off the coast Mon with front slowly approaching
from the W. SSW winds will increase from 10 kt Mon to 15 to 20
kts Mon night and 20-25 kt Tue with seas 2-4 ft Mon building
back to 4 to 7 ft Tue.
As of 300 PM Thu...NNE gale force winds are expected tonight
into Friday, as an area of low pressure lifts east to
northeastward well off the Carolina coast. These strong winds
will lead to minor soundside water level rises for areas
adjacent to the Southern Pamlico Sound, mainly Eastern Carteret
including the Core Sound area, and areas along the lower Neuse
River, as well as Ocracoke and Hatteras Island south of Buxton.
Minor inundation 1-2 ft (agl) are expected with local amounts up
to 3 ft possible Down-east Carteret, and a Coastal Flood
Advisory conts for these areas. A High Surf Advisory was issued
for the OBX from Cape Hatteras North this evening thru late Fri
night for 8 ft+ waves in the surf zone.
NC...Winter Weather Advisory until 10 AM EST Friday for NCZ195-196-
Winter Weather Advisory until 10 AM EST Friday for NCZ198.
Winter Storm Warning until 10 AM EST Friday for NCZ029-044>047-
Wind Advisory until 4 PM EST Friday for NCZ196-203>205.
Coastal Flood Advisory until 7 PM EST Friday for NCZ194-196-
High Surf Advisory until 1 AM EST Saturday for NCZ203-205.
MARINE...Small Craft Advisory until 5 PM EST Friday for AMZ136.
Gale Warning until 10 AM EST Friday for AMZ137.
Gale Warning until 7 PM EST Friday for AMZ135-150-152-154-156-
Gale Warning until 5 PM EST Friday for AMZ131-230-231.
Area Forecast Discussion
National Weather Service Marquette MI
642 PM EST Thu Feb 20 2020
.SHORT TERM...(This evening through Friday)
Issued at 401 PM EST THU FEB 20 2020
Clear skies and windy, warmer conditions are on the way. Water vapor
imagery and RAP analysis show a trof over eastern Canada and the
northeastern U.S. Upstream, a ridge is progressing across western N
America though a shortwave is cutting thru it over Alberta and the
NW Territories. Associated with this ridge, a 1045mb sfc high pres
is centered over the Central Plains. With winds backing wsw today,
waa underway and a very dry air mass advecting into the area in an
absolute and relative sense per upstream 12z KINL/KMPX soundings,
lake effect off Lake Superior has shifted offshore of Upper MI with
cloud streamers beginning at increasing distances from the upstream
shorelines. As a result, sunny skies are the rule across the fcst
area attm. Winds are already increasing on Lake Superior and nw
Upper MI as pres gradient begins to tighten btwn the strong high to
the s and a deep low pres way to the nw, dropping se along the
border of the NW Territories and Nunavut.
Although the aforementioned shortwave trof will reach northern
Ontario on Fri, the very dry air mass upstream will prevent any pcpn
concerns. In fact, there will be very little, if any, cloudiness
tonight/Fri given the dry air depicted on fcst soundings. So, will
be looking at clear skies tonight and sunny skies on Fri. Main fcst
issue will be wind as pres gradient continues to tighten over the
area btwn the Central Plains high pres drifting se and deep low pres
tracking se to Hudson Bay. Low-level jet will translate nw to se
across the fcst area late very late tonight thru Fri. Fcst soundings
show 50kt winds as low as 2kft. We`re now getting into the time of
year where the increasing sun angle begins to work on the lower
albedo forested terrain of Upper MI, increasing mixing heights and
the potential to mix to higher wind speeds. Wind gusts of 30-35mph
seem likely for much of the fcst area on Fri with some gusts to 35-
40mph across the the nw and n central. Would not be surprised to see
a few gusts to around 45mph during the time when the axis of max
pres falls shifts across the area. Min temps tonight will be a bit
of a challenge as very dry air mass that supports strong cooling
counters increasing winds. As is typical, winds over the interior s
central will be most decoupled. Temps should fall to around 5F above
there. Min temps should increase to 10 to 15F across the far w and
n, warmest over the Keweenaw. Max temps on Fri will range from
around freezing downwind of Lake MI to 35 to 40F elsewhere.
.LONG TERM...(Friday night through Thursday)
Issued at 146 PM EST THU FEB 20 2020
Upper air pattern consists of a 500 mb ridge across the Rockies with
a trough off the east coast and a closed low off the CA coast 00z
Sat. The closed low off the CA coast slowly moves east into the
central plains by 00z Mon. Quiet weather for this forecast period.
In the extended, the GFS and ECMWF continue to show a storm track
well to the south of the area across the Ohio River valley and the
southeast with one storm on Tue and another on Wed. We are on the
far northern periphery of both storms and will see some lake effect
out of them. Temperatures go from above normal for this forecast
period to below normal.
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 640 PM EST THU FEB 20 2020
With drier/warmer air advecting into the area, expect VFR
conditions to prevail thru this fcst period at KIWD/KCMX/KSAW.
Main concern will be winds. With strong high pres across the
Central/Southern Plains to the Ohio Valley and strong low pres
tracking se toward Hudson Bay, winds will be increasing during the
fcst period. Although sfc winds will become gusty (already at
KCMX and late tonight/early Fri morning at KIWD/KSAW), inversion
will remain, resulting in LLWS developing late tonight. Sfc winds
will likely gust to 25-35kt during Fri morning and higher gusts
near 35 kt may linger into the afternoon at KSAW.
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 401 PM EST THU FEB 20 2020
Tightening pres gradient btwn strong high pres ridge to the s and
deep low pres dropping se to Hudson Bay will result in 35-40kt gales
across mainly the w half of Lake Superior thru Fri aftn. Would not
be surprised to see gusts to around 45kt at times from around Isle
Royale toward the Keweenaw. Although temps are moderating, the
strong winds will still support hvy freezing spray thru early Fri
morning for much of the same area with the gales. Winds will fall
back to 20-30kt Fri night, to 15-25kt on Sat, and then to blo 20kt
for Sun/Mon. Arrival of colder air on Tue along with low pres
developing well to the s should lead to some increase of winds at
Heavy Freezing Spray Warning until 7 PM EST this evening for
Gale Warning until 7 PM EST /6 PM CST/ Friday for LSZ162-240>244-
Heavy Freezing Spray Warning until 9 AM EST /8 AM CST/ Friday
Heavy Freezing Spray Warning until 11 AM EST Friday for LMZ248-
Gale Warning from noon to 7 PM EST Friday for LMZ248-250.