Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/18/20
Area Forecast Discussion...UPDATED
National Weather Service Corpus Christi TX
1047 PM CDT Tue Mar 17 2020
Satellite, NDLN, and surrounding radar output depict convection
approaching the CWA from Mexico, consistent with upper jet
dynamics, and sufficient moisture/instability. The most recent
HRRR initialization/first few hours of this cycle depict the
position of the convection fairly well. The HRRR predict this
convection to enter the CWA around 06z Wednesday, then move across
the WRN CWA before effectively dissipating by 09z Wednesday.
Concur with this dissipation given movement away from the upper
jet forcing and increasing CIN. Adjusted the ZFP accordingly.
.PREV DISCUSSION... /Issued 729 PM CDT Tue Mar 17 2020/
Note Aviation Discussion below corresponding to the 00z TAFs.
A transition from VFR conditions/moderate onshore flow this
evening to MVFR ceilings/light wind overnight/early Wednesday
morning, along with isolated showers and thunderstorms generally
west of U.S. 281. Expect a transition to a mixture of MVFR/VFR
conditions Wednesday afternoon, along with increasing onshore
flow to moderate/breezy.
PREV DISCUSSION... /Issued 255 PM CDT Tue Mar 17 2020/
SHORT TERM (Tonight through Wednesday night)...
A slow-moving midlevel trough off the California coast will
continue to drift eastward through the short term. Ripples in the
flow around that trough will support increasing rain chances out
west tonight, as models hint at another thunderstorm complex
developing out over west Texas and northern Mexico and drifting
over the western brush country before fading out Wednesday
morning. After a lull during the day Wednesday, rain chances
increase yet again Wednesday night.
Temperatures will remain above normal through the short term as
onshore flow maintains low level moisture.
LONG TERM (Thursday through Monday)...
A mid-level trough with associated shortwave troughs will continue
to enter the region from the west Wednesday night into Thursday
before the passage of the cold front. These shortwaves will aid in
the development of shower activity moving in from Mexico and moving
towards the northeast. Rain chances will decrease Thursday night
before the passage of the cold front Friday afternoon or early
evening. With the front, upper level dynamics will support the
development of thunderstorms, mainly over the western areas of the
CWA. The cold front is expected to stall just offshore, maintaining
higher rain chances through the weekend before lifting back
northward late in the weekend. Rain chances should decrease Monday
as a weak to moderate onshore flow settles back in.
Warm temperatures Thursday in the mid 80s to low 90s will cool into
the 70s Friday and dip into the 60s Saturday due to a persistent
northeast flow under mostly cloudy skies with rain. Temperatures
will then slowly warm through early next week as onshore flow
Onshore flow will continue through Thursday. A cold front is
expected to sweep across the area on Friday with a moderate to
occasionally strong northeast wind behind it through Saturday
before becoming easterly by Sunday. Showers with isolated
thunderstorms are expected with this frontal passage, and will
continue through the weekend as the front is expected to stall
just off the coast before lifting back north early next week
resulting in a weak to moderate onshore flow.
.PRELIMINARY POINT TEMPS/POPS...
Corpus Christi 70 81 70 84 69 / 10 10 20 0 20
Victoria 69 81 70 82 67 / 10 10 20 20 40
Laredo 70 90 68 91 69 / 30 10 20 0 40
Alice 70 85 69 90 68 / 10 10 20 0 30
Rockport 71 77 70 78 68 / 10 10 10 10 30
Cotulla 69 88 68 90 64 / 40 10 40 0 60
Kingsville 71 84 69 90 69 / 10 10 20 0 20
Navy Corpus 69 77 69 78 69 / 10 10 10 10 20
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
626 PM CDT Tue Mar 17 2020
VFR conditions are in place across the region early this evening.
Earlier shower/storm activity near the I-35 sites has weakened.
Expecting the diurnal return to lower cigs with MVFR at all sites by
04-07Z and IFR likely in the 09-12Z time frame. At DRT, a strong
thunderstorm located 30-40 miles to the WSW as of 2330Z may move
close enough for VCTS in the next few hours, with additional storm
activity likely to impact the region in the 03-06Z timeframe. That
complex of showers and thunderstorms should decay as it approaches
the I-35 corridor between 08z and 12z Wednesday morning and may
produce VCSH at AUS and VCTS at SAT/SSF. Ceilings tomorrow will rise
to MVFR but should remain there through much of the afternoon along
the I-35 corridor, with VFR conditions not expected to return until
late afternoon or early evening.
.PREV DISCUSSION... /ISSUED 237 PM CDT Tue Mar 17 2020/
SHORT TERM (Tonight through Wednesday Night)...
Of note for this afternoon and evening the HRRR suggests a few
isolated showers and storms developing along and east of the I-35
corridor and moving north in the moist environment. While no other
model suggests this the radar trends along the Coastal Plains of
isolated storms developing support this solution. Have added slight
chance PoPs through the late afternoon to account for this.
As the main upper low continues to spin to the Southwest of
California a pair of shortwave disturbances will move across Texas
tonight and tomorrow night in the southwest flow aloft. Both of
these shortwaves are expected to interact with the West Texas
dryline and juicy atmospheric conditions to spark off complexes of
showers and storms along the Rio Grande Plains this evening and
overnight, and then again tomorrow evening and overnight. These
complexes will be strongest across the Rio Grande Plains and Edwards
Plateau producing a risk of strong to severe storms in addition to
some brief heavy rainfall potentially leading to some flooding
issues. The complexes will gradually weaken as they move to the east
towards the I-35 corridor both days. Isolated showers, and maybe a
few (non-severe) storms are possible Wednesday and Thursday morning
during the commute across the I-35 corridor. Wednesday day proper
should be cloudy but mostly dry with highs once again around 80
degrees. Overnight lows tonight and tomorrow night will remain in
the mid to upper 60s.
Diving a bit more into the thunderstorm threat the complex of storms
should begin impacting Val Verde County around and after about 9pm
this evening and then push eastward through the overnight and early
morning hours. Dewpoints in the 60s, and model soundings that show
CAPE (instability) of 1500-2000 J/kg along with 30-50 knots of bulk
shear will mean that the atmosphere is primed for storms as the lift
from the shortwave arrives. This will initially lead to the
development of isolated storms that should quickly organize into a
line as the mid-level jet kicks in overnight. The main threat will
be damaging thunderstorm winds and some hail. Brief heavy rainfall
could also result in some minor flooding.
Wednesday evening and overnight will be a repeat of tonight, with a
few important differences. The warm air inversion (or CAP) should
hold longer tomorrow, so the onset of storms appears later tomorrow
night with the second shortwave. In addition there appears to be
more shear tomorrow night and slightly less CAPE per model soundings
which would lend it more to damaging wind threat. The main energy
from the upper low will be pivoting across North Texas into the
Central Plains late tomorrow night so the strongest storms should
remain to our northwest. Regardless, the Storm Prediction Center has
our western areas in a Slight Risk both tonight and tomorrow night,
with a marginal risk extending close to the I-35 corridor.
LONG TERM (Thursday through Tuesday)...
A cold front will move through our CWA during the day Thursday. This
front will stall across South Texas and a second cold front will move
into Central Texas. This will lead to an extended period of chances
for showers and thunderstorms. Thursday rain chances will be best
over the eastern half of our CWA. Thursday night this area will shift
to the southern half of the area closest to the stalling front.
Chances will increase across nearly all of the CWA Friday with the
second front in Central Texas. Saturday the low level flow will turn
around to the southeast and bring the boundary back as a warm front.
This will continue the high chances for showers and isolated
thunderstorms Saturday and Sunday. Monday an upper level ridge will
move in from the west bringing an end to the wet pattern.
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 66 79 67 80 57 / 30 20 40 50 60
Austin Bergstrom Intl Airport 66 79 67 80 57 / 30 20 40 50 60
New Braunfels Muni Airport 66 79 66 81 59 / 30 10 40 30 60
Burnet Muni Airport 65 76 65 79 53 / 50 20 60 50 50
Del Rio Intl Airport 66 78 66 84 58 / 80 20 60 0 40
Georgetown Muni Airport 66 78 66 79 54 / 30 20 50 60 50
Hondo Muni Airport 68 80 67 84 57 / 60 10 50 10 60
San Marcos Muni Airport 66 79 67 81 57 / 30 10 40 40 60
La Grange - Fayette Regional 69 80 69 82 63 / 10 10 20 50 60
San Antonio Intl Airport 67 80 67 81 60 / 40 10 40 20 60
Stinson Muni Airport 69 81 68 83 61 / 40 10 40 20 60
Area Forecast Discussion
National Weather Service Green Bay WI
1045 PM CDT Tue Mar 17 2020
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Wednesday
Issued at 306 PM CDT Tue Mar 17 2020
The latest RAP analysis and satellite/radar imagery show high
pressure centered over southeast Iowa and central Illinois early
this afternoon. West-northwest winds north of this surface high
brought in a few clouds near the U.P. border, but otherwise, skies
have been clear across northern Wisconsin so far today. Looking
upstream, return flow is ramping up over the Plains as evident by
a surging low stratus deck into South Dakota. As the high shifts
east of the area, and increasing amounts of moisture move into the
western Great Lakes, light precip chances are the main forecast
concern through Wednesday afternoon.
Tonight...Skies look to start out mostly clear in the evening with
high pressure in close proximity to the region. With clear skies
and light winds, temps could very well tank across the snow-
covered northwoods in the evening, and lowered temps accordingly
(and still may not be enough). Clouds are expected to return and
lower late in the evening into overnight as winds shift to the
southwest aloft and draw in increasing amounts of moisture in the
mid-levels. Many of the mesomodels indicate precip developing
southwest of the region, and pushing towards central/east-central
Wisconsin by 12z Wed. Dry air wedges in the mid-levels suggest a
wintry mix of snow and freezing/rain drizzle is possible as precip
arrives, though little to no accumulations are expected prior to
Wednesday...Warm/moisture advection in the mid-levels will
continue to overspread the region during the morning, thereby
increasing chances of precipitation. With temps below freezing,
primarily before 15z, minor amounts of snow and ice will be
possible, which could impact the morning commute. Will continue to
highlight the possibility in the Hazardous Weather Outlook. Most
of the meso-models now have the heavier precip remaining south of
the area through the day, however. As temps warm and mid- level
moisture strips out, mainly looking at light spotty showers and
areas of drizzle for the afternoon. Under overcast conditions,
temps will only warm from the upper 30s to low 40s.
.LONG TERM...Wednesday Night Through Tuesday
Issued at 306 PM CDT Tue Mar 17 2020
Main focus in the long term is on precipitation amounts and types
Thursday and Friday.
Wednesday night...Will continue to see some lingering, light
precipitation across the area from Wednesday`s system. This will
mainly be rain, although some freezing rain or drizzle is
possible across north- central WI as surface temperatures will be
below zero. Moisture is little to none in the DGZ so do not expect
any snow. Precip Wednesday night will remain light, with only a
couple hundreths of QPF.
Thursday...Focus shifts to a more significant system moving out of
the southwest while a shortwave also approaches from the
northwest. Models currently to not phase these systems across the
area, with two main rounds of precipitation occurring. Strong WAA
ahead of the southern system will increase rain potential
throughout the morning, with rain likely area-wide by Thursday
afternoon. The forecast area is also in the favorable RRQ of the
upper jet, which will aid in lift during this time. Rain, likely
heavy at times, will continue through the afternoon, with
accumulation around 0.50 inches by 00Z Friday. Also of note, mid-
level lapse rates of 7.0 to 7.5 C/km could result in some isolated
Thursday evening...Southern stream shortwave continues to pass
through the area, while the northern stream shortwave also
approaches. We will continue to see upper support, now located in
the LFQ of an upper jet, along with frontogenetic forcing. This
will combine to produce up to another 0.50 inches of precip by 12Z
Friday. Not all precip will fall as rain during this time, as
boundary layer temperatures cool expect to see a changeover from
rain to snow from northwest to southeast. Current forecast calls
for 1 to 3 inches of snow across north- central WI, will less than
one inch elsewhere. Snow amounts in the Fox Valley and east-
central WI are only a tenth or two at most, but this may still be
enough to create some slippery roads.
Friday...Precipitation will end throughout the morning. With
rainfall totals from the past day anywhere from 0.75 to 1.00
inches, this could result in river rises and localized flooding
on Friday through the weekend.
Meanwhile, strong high pressure builds into the area on Friday
through the weekend which will act to keep the area dry and
cooler. This will also create gusty north to northwest winds on
Friday which could result in ice shoves on the Bay and Lake
Next week...There is a chance of lighter precip early next week,
but models diverge at this point, so confidence in exact timing is
low. Temperatures return closer to normal on Monday.
.AVIATION...for 06Z TAF Issuance
Issued at 1045 PM CDT Tue Mar 17 2020
VFR conditions will continue overnight, with middle and
high clouds increasing.
Warm air overrunning colder air near the ground will produce
ceilings lowering to MVFR from west to east Wednesday. There also
could be some very light snow or rain showers in the morning and
light rain showers in the afternoon.
MVFR/IFR conditions are expected Wednesday night with some light
Area Forecast Discussion
National Weather Service Gray ME
910 PM EDT Tue Mar 17 2020
Low pressure exits to the east this evening. High pressure
builds in Wednesday followed by additional chances of
precipitation the second half of the week. High pressure builds
in from the west this weekend.
.NEAR TERM /TONIGHT/...
Some areas of fog have developed and have included this in the
forecast wording. Dry air moving in from the west should help to
erode this fog later this evening from west to east.
Made a few adjustments to the forecast this evening. The bulk of
the rain has exited with only a few patchy spots of drizzle left
and a few snow flurries in the mountains. With winds shifting to
the west and cold/dry advection beginning, expect clouds to
clear out fairly quickly this evening. This will help dry things
12Z models remain in good agreement continuing with rain and
snow showers, with also patchy drizzle and fog through the
remainder of the afternoon. The HRRR appears to have a good
handle on the timing of the precipitation exiting the region. As
low pressure exits through the Gulf of Maine this evening,
drier air will enter the region on westerly winds. Clearing will
take place from southwest to northeast this evening. The
exception will be the mountains which will hold on to a few
scattered upslope snow showers.
The clearing skies overnight will combine with westerly breezes.
This will keep temperatures mainly in the 20s for overnight
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
High pressure will quickly crest over the region on Wednesday.
Weak cold air advection is expected during the day. However,
with sunshine, temperatures will top out over 50 degrees over
southern New Hampshire. The rest of the region can expect
temperatures in the 35 to 45 degree range. There will likely be
some mid and high level clouds crossing the region during the
As high pressure exits off the coast Wednesday evening, a short
wave will quickly approach from the west. A broad area of warm
air advection will ride up the East Coast. As this occurs, a
weak wave of low pressure will develop along or near the New
Jersey coastline. This will allow for precipitation to enter
much of the forecast area before sunrise. Temperature profiles
suggest the precipitation will mainly be in the form of snow,
possibly mixing with rain along and near the coastline.
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Subtropical ridging positioned over the southeast CONUS/Gulf of
Mexico breaks down through the end of this work week as the
northern and southern streams phase and sweep a long wave trough
across. High pressure gradually builds back into the region by
early next week with a period of quiet weather.
Continuing from the short term...a compact shortwave crosses
during the first half of Thursday and delivers a quick hit of
precipitation, on the order of about 0.3-0.6" QPF focused
across the south into the Whites with some SE-facing upslope
flow. As has been discussed with WPC this afternoon, peak
intensity could align with the Thursday morning commute, so
although snowfall accumulations will be rather minor before the
mid-morning switch to rain there could be impacts to commuters
in southern NH and ME.
Meanwhile upstream, a southern stream shortwave ejects from the
southern Rockies NEward into the Plains and begins to phase
with a northern stream wave coming down from the Canadian
Rockies. This feature produces convection along a cold front
extending from the southern Plains up into the Ohio Valley by
Thursday night. At the same time, deep southwest flow sends a
warm front into the northeast CONUS. Warm frontal forcing and
increasing baroclinicity keeps generally showery conditions
Thursday night into Friday as temperatures gradually warm. High
temperatures on Friday reach into the 50s to near 70 across the
area with dew points reaching well into the 50s. Temperatures
aloft rise well above freezing as well so wintry precipitation
becomes a non-issue as well.
During the second half of Friday, the long wave trough
approaches from the west with one or two cold fronts depending
on the degree of phasing and mesoscale forcing. An early look at
ingredients suggests thunder is on the table as the cold
front(s) crosses, but will depend on convective initiation
upstream. Ensembles are hardly convinced with only about a third
of members of the EURO and GFS ensembles including elevated
instability/CAPE, so confidence doesn`t quite exist yet to
include thunder in the forecast, especially with somewhat
fickle mesoscale components on day 4. Although any convection
wouldn`t be particularly strong, PWAT increasing to 3-4 SD above
normal does leave some concern for locally heavy rainfall.
Friday evening into the overnight, the main cold front
associated with the northern stream crosses with a strong dry
trend to follow. Expect a period of upslope showers and clouds
to linger into Saturday morning, but thereafter high pressure
returns with temperatures returning to around normal this
weekend. Quiet weather continues into the next work week with
the next chance of precipitation coming sometime in the Monday
to Tuesday time frame, however model agreement is low for that
portion of the forecast.
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Short Term...Conditions rapidly improving to VFR this evening
and continue through Wednesday.
IFR in snow is likely Thursday morning across southern terminals
in particular with MVFR to IFR ceilings. Snow gradually switches
to rain Thursday and Thursday night, becoming showery, so while
MVFR (locally IFR) will likely occur in some places some of the
time it won`t be the rule except for perhaps over the mountains.
A cold front with possible convection crosses late Friday, then
high pressure and VFR conditions return for the weekend.
Short Term...SCAs will continue until 6 pm in the Bays before
winds and seas subside. Thereafter, expect SCAs to continue in
the outer waters until early Wednesday as it will take several
hours for the seas to subside.
Long Term...A compact, quick-hitting wave crosses Thursday with
a period of SCAs possible over the waters. After a brief break,
a cold front crosses late Friday with another period of SCAs
possible over the waters, switching offshore after the front.
MARINE...Small Craft Advisory until 10 AM EDT Wednesday for ANZ150-152-
NEAR TERM UPDATE...Kimble
Area Forecast Discussion
National Weather Service Louisville KY
955 PM EDT Tue Mar 17 2020
Issued at 955 PM EDT Tue Mar 17 2020
Most areas have cleared out this evening, with the exception of the
Lake Cumberland region. Refined sky cover trends overnight into Wed
morning to feature a somewhat briefer period of "mostly clear." By
03-06z tonight, stratus is expected to begin pushing back north over
southern KY. Sfc high pressure is currently centered over southern
OH, and developing southerly low level flow on the backside of that
system will bring clouds back north.
Temperatures will drop slightly under mainly clear skies, but not
much, from this point forward. Look for lows to settle in the upper
30s to mid 40s.
Still looking at a marginal/low end severe threat on Wednesday. The
past several HRRR runs have been notably hot, but its sfc dewpoints
look a little high compared to the rest of the HREF members. The
severe risk does appear to be slightly higher over the southern half
of KY, where instability is greatest. More widespread precip with
embedded convection appears more likely over southern IN and
northern KY in a very marginal thermodynamic environment.
.Short Term...(This evening through Wednesday)
Issued at 255 PM EDT Tue Mar 17 2020
Bubble of sfc high pressure over the Great Lakes is nosing southward
into the Ohio Valley, and is finally clearing our skies from north
to south. Expect that trend to continue at least into this evening.
Temps could flatline after midnight as weak SE return flow starts to
develop. Next weather system is a sneaky mid-level wave
currently along the NM/TX border.
That wave aloft will lift fairly quickly to the ENE on Wednesday,
with precip quickly spreading into southern Indiana and central
Kentucky in the late morning/early afternoon. As the warm front
lifts through a compact mid-level jet will translate NE across
Kentucky, providing just enough dynamics to support a marginal SVR
threat. Damaging winds will be the main hazard, but with a warm
front in play we can`t rule out a stray tornado. Most of our
Kentucky counties are highlighted in the SPC risk, but if severe wx
actually does occur it will be more concentrated than that due to
the compact and transient nature of this feature. Main limiting
factor will be instability, as profiles are nearly moist-adiabatic
and any CAPE will be (relatively) tall and skinny. North of the warm
front it will be more of a steady rain, thus quashing all SVR
threat, and QPF during the day should be just over a half inch.
.Long Term...(Wednesday night through Tuesday)
Issued at 300 PM EDT Tue Mar 17 2020
Overview...West Coast troughing and East Coast ridging will set up W
to WSW zonal flow over the eastern half of the US. A few shortwaves
will eject eastward bringing rounds of rain and possible storms to
the Ohio Valley.
Wednesday night through Friday...The weaker of two shortwaves will
be over the Upper Great Lakes and Ohio Valley Wednesday night as
showers and possible storms continue through Thursday early morning.
SW flow will provide copious Gulf moisture while theta-e ridging
will result in PWAT values over 1.50" at times. Cells appear to be
more efficient rainers than thunder producers given the long, skinny
yet meager CAPE profiles, but celeritous mid and low level jetting
with respectable shear profiles suggests the possibility of
thunderstorms, some of which could be severe. As a result, SPC has
placed most of central Kentucky within a Day 2 Marginal risk with
damaging winds being the main hazard of concern. A brief lull in
rainfall intensities will be seen Thursday morning before the second
and stronger shortwave approaches from the west.
Thursday through Friday...The surface low will advance from the
Central Plains Thursday afternoon and past the Great Lakes by Friday
morning as its attendant cold front sweeps through the Ohio Valley
bringing another round of moderate to heavy rain and a better chance
of thunderstorms. Thermodynamic and kinematic profiles are beginning
to look better, especially across our southern counties. Damaging
winds are a possibility as a strong LLJ of 55-60KT overspreads the
region Thursday evening. Low LCLs with strong low level shear and
CAPE also suggest potential for isolated tornadoes. Storms and heavy
rainfall should begin to wane by Friday morning as the bulk of the
energy moves east of the area.
Heavy Rain and Flooding...These two systems are projected to result
in approximately 1.50 to 3.00 inches of total rainfall accumulation
with higher amounts across the northern half of our counties. OHRFC
Flash Flood Guidance is currently at 2 to 3 inches across the CWA,
Therefore, humectant soils and stressed rivers could pose flood
concerns by Friday. Will continue to monitor this potential closely.
Saturday and Beyond...Canadian high pressure builds across the
region resulting in colder temperatures this weekend with mornings
lows in the 30s for Saturday and in the 20s for most on Sunday.
Highs Saturday will be in the mid to upper 40s and Sunday in the
upper 40s to lower 50s. Next chance of rain comes late Sunday night
.Aviation...(00Z TAF Issuance)
Issued at 739 PM EDT Tue Mar 17 2020
A period of VFR with mainly clear skies is expected late this
evening into the first half of the overnight period. Beyond 06-08z,
BKN stratus is expected to begin lifting back north across the area
along and north of a surface warm front. Winds will be generally
light and variable overnight, but with a gradual veering trend. A
light wind out of the east is expected around 12z Wednesday. Winds
will then quickly veer out of the southeast Tue morning and out of
the south by Tue afternoon. Also look for increasing winds Tue
afternoon as well. Went ahead and included LLWS at HNB in particular
due to a strong low level jet that will be focused over Indiana by
As the warm front lifts north tomorrow morning, MVFR ceilings will
become more common with still some VFR mixed in east of I-65.
Ceilings will deteriorate faster at HNB and SDF through the midday
hours. Widespread showers and scattered thunderstorms are expected
to move across HNB/SDF/LEX after 18-19z and continuing through the
end of the period. Scattered showers and storms will also be
possible at BWG by mid to late afternoon.