Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/31/21
AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
951 PM EDT Tue Mar 30 2021
Low pressure approaches from the west on Wednesday with a
strong cold front crossing the area Wednesday night, bringing
widespread showers and possibly thunderstorms. Canadian high
pressure builds in for the end of the week.
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 950 PM EDT Tuesday...
High pressure remains centered well offshore this evening. Low
pressure is centered over Hudson Bay, with a cold front
extending SSW through the Great Lakes and Mississippi Valley.
Meanwhile, an upper trough is located over central Canada and
the Northern Plains. Mainly clear this evening with some thin
high clouds. Temperatures are mainly in the mid 50s to low 60s
with a light SSE wind.
Surface high pressure will push farther offshore overnight. High
clouds are expected to increase from west to east, with some
mid clouds arriving toward morning. PW values steadily increase
through the night, with a slight chc of sprinkles or widely
scattered showers prior to sunrise Wednesday, mainly across
southern VA and interior NE NC. Milder tonight with ongoing
WAA, with lows mainly in the low/mid 50s, with some upper 40s
near the Atlantic coast of the MD Ern Shore.
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
As of 340 PM EDT Tuesday...
An upper-level trough swings east on Wednesday, taking on a neutral
to slightly negative tilt with time late Wed into Wed night.
Meanwhile, a sfc low pressure system is expected to develop across
the Deep South and track northeast along the Appalachian Mountains.
Overall, 12z models are still varied with timing and evolution of
the rain Wed. The HRRR tries to bring the heaviest precip in the
late afternoon/early evening associated with a prefrontal trough
whereas the NAM tries to bring the heaviest precip overnight along
the cold front. Therefore, have gone with a blend of CAMs for the
timing and QPF. Expect showers to increase in coverage through the
morning with the first round of precip before a break for midday.
CAMs are still split with respect to exact location of the warm
front into late Wed, but expect Hampton Roads area to stand the best
chance at breaks in the overcast in the pseudo warm-sector, and
hence some modest destabilization. However, for the most part, still
expect widespread cloud cover to significantly mitigate
destabilization potential for the area. That said, GEFS and 12z/30
EPS still showing precipitable waters in the 1.25"-1.50" range. This
should lead to at least a couple of bands producing moderate to
locally heavy showers Wed afternoon into Wed night with the second
and third rounds of precip with the prefrontal trough in the late
afternoon/early evening and the cold front overnight. CAMs have also
begun to show a light to moderate stratiform rain developing behind
the cold front and lingering into Thurs morning and perhaps a few
isolated showers Thurs afternoon if enough moisture remains. Given
rains of the past weekend, localized/urban flooding will need to be
monitored Wed evening into Thu morning for the entire CWA. WPC has
placed nearly all of the CWA in a marginal risk of excessive
rainfall to account for this possibility. Isolated thunder in the
heaviest bands will also be possible.
The aforementioned questionable destabilization (odds are still in
favor of lower destabilization as opposed to higher) and nocturnal
approach of the front should act to minimize any potential severe
wind threat with the line of showers/storms that develops, although
gusty showers are likely with and behind the strong front, with
gusts of 25-40 MPH possible Wed night. QPF generally 1" to 1.5" but
locally higher amounts possible in central VA and the VA northern
neck where banding is more likely to occur.
Showers move offshore Thu morning apart from a stray afternoon
shower, with a gradually clearing sky (still partly cloudy) Thursday
as cool Canadian high pressure begins to build in from the west. Dry
and cool weather lingers through the end of the week.
Highs Thursday ranging from the upper 40s to around 50F NW to the
mid-upper 50s SE. Highs Friday in the upper 40s to around 50F. Lows
Wed night ranging from around 40F NW to the mid 40s SE. Much colder
Thurs and Fri nights with a hard freeze likely for most of the FA.
Lows Thurs night in the mid to upper 20s NW to the upper 20s to
lower 30s SE. Lows Fri night in the upper 20s NW to the lower 30s
SE. Climatologically, btwn April 1st-8th, only zones that would need
a frost/freeze headline are across sern VA/ne NC (basically s/e of a
ORF-SFQ-RZZ line). Frost/freeze headlines not needed NW of this line
until after April 8th.
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
As of 315 PM EDT Tuesday...
Continued cold but dry Fri night into early Sat as the model
consensus remains good for ~1030mb+ sfc high pressure to build E
from the TN Valley into the Carolinas and Virginia. With less
wind than Thu night/Fri morning, temperatures Fri night into Sat will
be similar (or in some cases slightly colder) with another
fairly widespread freeze expected with lows in the mid-upper 20s
to lower 30s. The sfc high is progged to become centered over
the SE CONUS from late Sat into at least the early portion of
next week as the flow aloft will be from the NW in a confluent
zone between a mean trough off the NE or New England coast and
a mean ridge over the MS Valley. This pattern will bring a
warmup back to climo normals along with dry conditions. Highs in
the upper 50s to lower 60s on Saturday, with lows in the 30s to
lower 40s Sat night. Easter Sunday looks dry and mild with
highs in the mid 60s to low 70s. Models do differ a bit with
respect to the potential for a secondary cold front dropping
south into the region late Sunday into Mon, as another area of
high pressure builds S over eastern Canada. For now it still
looks dry regardless, with a bit more uncertainty regarding
temperatures. Following the blends for now with highs mainly in
the 60s to around 70F near the coast to 70-75F well inland Mon-
.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
As of 755 PM EDT Tuesday...
High pressure is centered well offshore as of 00z, with a cold
front well to the W of the area across the Mississippi Valley.
Mostly clear this evening, with a SSE wind generally 5-10kt for
most areas, with some occasional gusts to 15-20kt at ORF/PHF.
Clouds will increase overnight as the cold front approaches from
the W. However, VFR conditions are expected to prevail through
12z Wednesday for most of the area, although some MVFR cigs are
possible SW of RIC prior to 12z. MVFR cigs are expected to
develop at RIC after 12z, with most other sites prevailing VFR
through 18z. Some pre-frontal scattered showers are possible
between 12-18z, and these could produce brief MVFR vsby if they
were to affect a TAF site. Showers and some embedded tstms
increase in coverage after 18z. MVFR cigs become more
widespread, with IFR cigs possible from RIC-SBY late in the
forecast period (20-00z). Additionally, any showers/tstms could
produce brief IFR/LIFR vsby in heavy rain.
The cold front pushes through the area Wednesday night into
Thursday morning with additional rain and degraded flight
conditions. A NNW wind has the potential to gust to 25-30kt
early Thursday, especially toward the coast. Remaining breezy
Thursday as Canadian high pressure builds in from the NW. This
area of high pressure then prevails Friday into next weekend.
As of 340 PM EDT Tuesday...
This afternoon, high pressure continues to move further offshore
with S to SE winds over the waters. Wind speeds are generally 10 to
15 knots. Winds are locally higher, 15 to 18 knots with gusts to
around 20 knots, across the Lower Chesapeake Bay. Seas and waves
in the Bay are generally around 2 feet.
Winds may continue to gust to around 20 knots for portions of the
Chesapeake Bay, especially elevated sensors, into this evening
before relaxing tonight. SE winds will generally range from 10 to 15
knots tonight into Wednesday morning. Seas build to 2 to 4 feet,
while waves in the Bay build to 2 to 3 feet this evening into
tonight. A strong cold front approaches the region through the day
on Wednesday before crossing the waters Wednesday night into early
Thursday. Behind the front, winds become NW and increase to 25 to 30
knots. Local wind probs still show the potential for a brief period
of Gales Thursday morning, but probabilities still remain in the 30-
50% range. Will continue to hold off on any Gale Watches at this
time due to the short lived nature of these gusts and lower
confidence. Gusty NW flow will continue through the day Thursday
into Friday and Small Craft Advisories will be needed for this
period. Winds slowly decrease Friday and become sub-SCA by Friday
night or early Saturday. The offshore nature of the winds should
keep seas from building substantially, generally have seas building
to 5 to 6 feet (up to 7 feet out 20 nm) Thursday and lingering into
Friday. Waves in the Bay will range from 3 to 5 feet Thursday and
subside to 2-3 feet later Friday into Saturday morning. Calmer
marine conditions return for the weekend as high pressure builds
back over the region.
Area Forecast Discussion
National Weather Service Birmingham AL
705 PM CDT Tue Mar 30 2021
For 00Z Aviation.
/Updated at 148 PM CDT Tue Mar 30 2021/
Today through Wednesday.
A positive tilted longwave trough extended from Southern Canada
southwest over the Four Corners States while toward the surface a
warm front extended from Texas to Florida along the Northern Gulf
Coast while a strong cold front extended from an occluded low over
Southern Canada that extended southwest across the Midwest into
the Southern Plains.
Expect the trough to approach the area by the end of the short-
term forecast period while the warm front will lift northward
across the area this afternoon and evening while the cold front
approaches the Mid South region. The entire warm sector will be
warm sectored after midnight tonight as the cold front nears the
Mississippi River from the northwest. The cold front will move
into our northwest counties toward daybreak and continue advancing
southeast through the day on Wednesday.
Showers with a few thunderstorms will develop along and ahead of
the warm front this afternoon and evening with the better chances
initially southwest, expanding north and east with time overnight.
Showers and storms will remain possible across the northwest
overnight ahead of the approaching cold front.
Convection is expected to gradually decrease in intensity as
storms move into our northwest counties early tomorrow morning due
to minimal instability with the time of the day. Some convective-
allowing models are depicting more vigorous convection across
Northeast Mississippi into the Tennessee Valley region during this
time as better dynamics are modeled across this area.
We expect showers and thunderstorms to move southeast along and
develop ahead of the front as it advances southeast across the
forecast area during the day on Wednesday. We continue to
advertise severe weather potential across much of our forecast
area with higher chances generally along and south of the
Interstate 20 corridor as low-level instability values will
increase with time as the front moves further southeast. There
will be sufficient wind shear and the presence of a strengthening
low-level jet aloft for organized severe thunderstorms posing a
risk for damaging winds and large hail, especially across the
central and southern counties with the increasing unstable airmass
expected by the afternoon hours.
Another hazard introduced today is the potential for localized
flooding, generally near and north of Interstate 20 as
precipitable water values exceed 1.7 inches from late tonight
through Wednesday morning. Some of these areas are already
impacted by river flooding, which would further be amplified by
runoff from already moist soils in this area. A flash flood watch
has been issued for this area starting 7 pm tonight through 7 pm
Southeasterly winds will be breezy 10-15 mph today with gusts to
20 mph possible today and tonight followed by winds shifting out
of the northwest 10-20 mph with strong cold air advection behind
the front as it moves southeast across the area.
/Updated at 433 PM CDT Tue Mar 30 2021/
Wednesday night through Monday.
Extended grids were freshened up with the latest data. After the
convection exits Wednesday evening a large surface ridge will
build over Eastern Conus. A welcome rain free weather period will
commence as a result. However, with a 1032-1035mb ridge center
setting up over this area and lots of cold air advection into
Central Alabama around the ridge, colder than normal temperatures
are expected. Freezing temperatures and maybe a little frost are
possible in the far northern counties for early Thursday. Winds
will remain elevated for much of the night, so frost should be
patchy at best. Friday should be the coldest morning this week
with freezing temperatures possible across much of Central
Alabama. With clear skies and light to near calm winds expected,
more frost is likely. Finally, Saturday will have freezing
temperatures once again but for less of the area than Friday and
for not as many hours. Frost will be possible once again across
much of the area. Daytime temperatures will moderate through the
extended with ample sunshine.
Previous long-term discussion:
/Updated at 332 AM CDT Tue Mar 30 2021/
Wednesday through Monday.
Shower and thunderstorm activity will be concentrated along and
north of I-59 through noon Wednesday near and just ahead of an
advancing cold front. Pressure falls will take place along the
front Wednesday afternoon as a strong vort max pivots through the
base of a larger trough. With dewpoints in the mid to upper 60s,
SBCAPE of 1500-2000 J/kg should develop in the warm sector by
early afternoon as temperatures rise into the 70s to lower 80s
south of I-59. As surface convergence increases and height falls
overspread the area, thunderstorms will form in the vicinity of
the front in the presence of deep-layer shear of 40-50 kt.
Initially, storms may be in the form of a broken line and
supercells, with a potential for quarter size hail and damaging
winds. Fairly rapid upscale growth seems likely with an increasing
damaging wind threat. Both the GFS and HRRR explicitly show a
rear inflow jet of 50-55 kt developing behind bowing segments
across our central and southeastern counties. This is quite a
strong indication of damaging wind potential and supportive of a
local upgrade to Slight Risk. An upgrade to an Enhanced Risk for
damaging winds could become necessary.
Strong cold advection is expected behind the front Wednesday night,
and the cool conditions will continue through Friday. Winds early
Thursday morning may remain too strong for frost to form, but a
fairly widespread frost may occur Friday morning. Many locations
could see temperatures dip below freezing as well. Another frost is
expected Saturday morning due to strong radiational cooling. High
pressure and dry conditions will remain in place through Monday with
a warming trend expected for Saturday through Monday.
00Z TAF Discussion.
A warm front was moving northward over Central Alabama at this
writing. The front will usher in surface dew points in the middle
to upper 60s. A line of mainly showers was located near the front
and will affect MGM/TOI for the next hour or so and the rest of
the terminals through 04-06z or so. Thereafter, the most numerous
convection will be west and north. Ceilings will drop to MVFR and
then some IFR after 06z, with south winds remaining 5-10kts with
a few gusts.
By 12z, scattered showers and some thunderstorms will be present
near all the northern terminals. A cold front will move into the
area around 18z spreading showers and thunderstorm chances to all
terminals. Northern terminals may experience a brief rise in
ceilings, then back down. Southern terminals will jump to VFR and
back down as front approaches. The best chance for any fog will be
near TOI , where LIVFR conditions are briefly mentioned.
Winds shift to the north northwest around 10kts and gusts to near
20-25kts after 19z starting in the north.
Southerly flow will bring an increase in winds, moisture, and
rain chances through Wednesday. Much cooler and drier weather is
expected behind a cold front with afternoon RH values of 25 to 30
percent on Thursday and Friday.
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 63 71 33 52 28 / 80 100 30 0 0
Anniston 63 75 35 54 30 / 60 100 40 0 0
Birmingham 65 71 36 53 31 / 70 100 20 0 0
Tuscaloosa 66 73 36 56 31 / 70 100 20 0 0
Calera 64 74 35 54 31 / 60 100 30 0 0
Auburn 62 78 39 55 32 / 30 100 80 0 0
Montgomery 63 81 41 58 33 / 30 100 80 0 0
Troy 64 81 41 58 33 / 20 90 80 0 0
Flash Flood Watch through Wednesday evening for the following
Area Forecast Discussion
National Weather Service Quad Cities IA IL
612 PM CDT Tue Mar 30 2021
Issued at 245 PM CDT Tue Mar 30 2021
A cold front passed through the area today which has led to gusty
NW winds of 20 to 35 mph. The post-frontal air mass is very dry
with dewpoints in the 20s. Temperatures as of 230 PM ranged from
59 F in Macomb and Sterling to 45 F in Independence
There is an elevated grassland fire danger through this afternoon,
especially west of the Mississippi River, where the strongest
winds are anticipated.
.SHORT TERM...(This Evening through Wednesday)
ISSUED AT 245 PM CDT Tue Mar 30 2021
Winds will subside this evening into tonight, but remain steady
around 10 mph. Increasing pressure gradient on Wednesday will
result in another gusty day with NW winds reaching around 30 mph.
Therefore outdoor burning is discouraged once again due to an
elevated grassland fire danger. Forecast temps are 10 to 15
degrees below average with upper 30s far north to mid 40s far
Large inverted-V profile on forecast soundings and presence of low
SBCAPE, suggest not only gusty winds, but also shallow convective
cloud development during the afternoon. Very low confidence on
whether any precip will reach the ground because the sub-cloud
layer will be very dry. If anything forms, it may be mostly virga
with precip quickly evaporating below the cloud bases. The HRRR
and RAP are aggressive with snow showers during the afternoon but
seem overdone right now. Did not mention precip in the forecast
with this update, but it`s something will have to watch for.
.LONG TERM...(Wednesday Night through Tuesday)
ISSUED AT 220 PM CDT Tue Mar 30 2021
Initially quiet and very cold followed by a warming trend. Then a
progression of more fronts through the area.
Assessment...high confidence on freezing temperatures.
Quiet and cold conditions will be seen across the area Wednesday
night as high pressure moves through the area. Low temperatures look
to be around 10 degrees below normal which would place readings in
the 20 to 25 degree range.
Thursday through Sunday
Assessment...high confidence on temperatures trending above normal
Quiet and dry conditions will be seen Thursday through Sunday with a
warming trend as southerly flow develops across the area. Windy
conditions still look on tap for Friday and potentially Friday night
across the area. Temperatures by Sunday look to be in the 70s.
Sunday night through Tuesday
The global models vary on their solutions but suggest the potential
for one or more fronts to move through the Midwest. Although the
warmer temperatures will increase moisture, it will still remain
Given the timing and position differences among the models, the
model consensus has mainly dry conditions Sunday night and Monday
followed by slight chance pops Monday night and Tuesday. Depending
upon the position of the fronts, temperatures will either be well
above normal or near normal.
.AVIATION...(For the 00Z TAFS through 00Z Wednesday Evening)
ISSUED AT 609 PM CDT Tue Mar 30 2021
VFR conditions will prevail through the TAF period. Gusty
northwest winds seen today will continue through part of the
evening, dying down to around 10-15 KTs. Tomorrow, gusty northwest
winds will return. Winds around 15-20 KTs can be expected, with
gusts up to 25-30 KTs.
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1034 PM EDT Tue Mar 30 2021
Moisture increases tonight ahead of an approaching cold front. This
strong cold front pushes across our region from the northwest on
Wednesday, bringing a round of showers and thunderstorms. After that
cold front moves through Wednesday night, expect some unseasonably
cold weather for the end of the week. Expect an upper level ridge to
build over the region from Sunday into next week with warmer
.NEAR TERM /THROUGH WEDNESDAY/...
As of 1030 PM: Low clouds are continuing their slow northward trek
across the area. Radar remains PPINE for now, with the main area of
precip to our southwest. Have slowed precip timing in line with this
trend and latest mesoscale guidance. When precip does develop, it
will remain generally light until near or shortly after daybreak
when coverage and intensity ramps up. Winds have shown a diminishing
trend as well. Overnight lows still look on track.
Tonight, the dominant feature in our pattern will be
the deep sfc ridge over the western Atlantic. Continuing warm
upglide over the airmass will bring stratocu in increasing numbers
this afternoon from south to north, and a shallow stratus deck over
the CWA by tonight. This upglide will precede the eventual arrival
of a strong cold front tomorrow night. Overnight QPF response from
the hi-res models is paltry in areas not subject to terrain
enhancement in southerly flow; the setup is looking pretty
unremarkable at that time in that regard, but moisture will deepen
and dynamic lift will arrive in the morning nearer the cold front.
The most certain aspect thereof is the upper divergence in RR quad
of the jet streak in exit region of approaching trough, for which
there is a decent consensus among guidance and has been consistent
from run to run. The latest avbl GFS and WRF-NMM appear to be
kicking off some convection tonight over the TN Valley, which
arrives in our area soon after daybreak. This leads the models to
sharply increase QPF earlier than the other models would suggest.
Can`t say this is out of the question given position of sfc front
and aforementioned jet, but also can`t say this isn`t convective
feedback or a similar model artifact. At any rate, most likely
there will be a peak in precip coverage/rates between around
daybreak and noon as the best moisture/forcing traverse the
mountains. Deep quasi-unidirectional flow, roughly oriented along
the approaching front, still looks to be associated with anomalously
high PWAT values of +2.5 to +3 SD. Rates are expected to be most
significant 12-18z, but additional heavy rain likely will redevelop
with prefrontal convection late in the day. Flash Flood Watch being
issued for SW NC, the SC mountain zones, and Rabun/Habersham
Counties GA. Categorical PoP will follow the best forcing from the
mtns into the NW NC Piedmont, timed morning to early afternoon.
Otherwise, low stratus is expected to have developed by daybreak
over the Piedmont, and guidance signal is strong for this to linger
thru midday, possibly into the afternoon; weak midlevel lapse
rates may serve as a cap, so the day may take on characteristics
of in-situ CAD. This accordingly suggests a stabilizing effect
over much of the CWA. Furthermore we will we lose some of the
dynamic forcing by peak heating and after enough time has passed
to expect some lifting/scattering of the clouds near the effective
wedge boundary. Thus, expecting PoPs to drop off for a time in the
aftn over the mtns/NW Piedmont, and remain steady in the chance
range for much of the day away from the terrain, mainly to reflect
possibility of elevated convection. LCLs will be fairly low, and
deep layer shear already strong, so can`t rule out some discrete
cells or loosely linear clusters posing some risk of damaging
wind. CAPE profiles likely skinny so hail risk not looking that
high. A line of convection is expected to take shape ahead of
the cold front during the aftn, progressing across the CWA into
evening. The primary severe threat is expected to unfold with
this line; 0-1km shear will continue to be a limiting factor for
tornado threat, though damaging wind risk may increase.
.SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 115 PM Tuesday: Based on the SPC HREF handling of the timing
and magnitude of deep convection rippling acrs the piedmont late in
the day and into Wednesday evening, categorical coverage of showers
and storms will be progressively maintained into the I-77 corridor
until about midnight. With ensemble mean SBCAPE values approaching
1000 j/kg near CLT metro by 22z and marginally notable bulk shear
values there will remain the possibility of isolated storms stout
enough for damaging wind gusts and perhaps a spin-up. In addition
to the piedmont svr storm threat Wednesday afternoon and evening, a
round of heavy and perhaps marginally excessive rainfall is probable.
Flash Flood guidance is still low, with river/stream levels elevated
from recent heavy rain in the mountains. A strong SWLY LLJ will pump
in PWATS over 1.5" and in conjunction with strong upper level
divergence within a RRQ of the associated upper jet, and upslope
enhancement, rain rates may exceed FFG.
In the wake of the sharp cold fropa Wednesday night, 85H 0 deg C
isotherm is expected to plunge into the cwfa. Period of NW flow
snow showers remains likely to be supported within the brisk and
chilly post frontal airmass. It is still probable that a couple of
inches of fresh snow accumulation will occur in the typically
favored NW flow snow areas of those NC counties bordering Tenn.
Based on the progged pressure gradient and degree of CAA, stout wind
gusts are possible into Thursday morning setting us for a winter
like day featuring maximum temperatures 15-20 deg F below normal.
The cold high pressure system will reach the Ohio and Tennessee
valleys Thursday night, allowing winds to weaken over the area. But
a lingering wind/lack of decoupling is expected. CAA should still
bring temps down into the teens to mid 20s in the mountains and mid
20s to lower 30s across the Piedmont. These temps will probably
warrant a Freeze Warning the areas that will be turned on April 1st.
Will continue to mention in the HWO. The current forecast lows for
April 2nd approach or break record lows (see Climate section below
for more info).
Sfc ridging axis will continue to build toward the Southern
Appalachians on Friday loosening the pressure gradient, but even
under abundant early April sunshine, maximum temps may only warm to
about 5 deg F from the cool Thursday`s readings.
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 130 PM Tuesday: We may be dealing with a Frosty morning on
Saturday, but expect a quick warmup back to only a category below
climo for maxes. As the upper pattern continues to deamplify through
the weekend, quiet wx conds will linger through Easter Sunday and
with the warming trend continuing, we should be back into the lower
70s across the Piedmont. The suppressed atmosphere should continue
into the start of the workweek with ongoing warming Monday afternoon
with persistence temperatures fcst for the new day 7, Tuesday.
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
At KCLT and elsewhere: Low VFR clouds moving in from the south
nearly on schedule. These clouds will continue to spread north
through the evening. S to SW wind with occasional low end gusts
expected to continue as well. Cigs drop to MVFR then IFR to LIFR
overnight as moisture and isentropic lift increase. MVFR to possibly
even IFR vsby develops as showers increase in coverage. Winds
diminish but remain S to SE. KAVL will see the potential for LLWS
between midnight and daybreak with some stronger low level winds.
Shower chances briefly diminish late in the morning with improving
vsby. Cigs increase to MVFR. Showers and scattered TSRA develop for
the afternoon, have PROB30 in place for those. SW winds will low end
gusts expected for the afternoon.
Outlook: A strong cold front will blast across the region Wednesday
night, ushering in VFR for the rest of the week. Expect gusty N to
NW winds Wednesday night and Thursday morning.
02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 90% High 95% Med 68% Med 78%
KGSP High 88% Med 78% High 95% High 84%
KAVL High 97% High 83% High 87% High 87%
KHKY High 94% High 84% Med 73% High 88%
KGMU High 90% High 81% High 97% High 84%
KAND High 90% Med 77% High 93% High 81%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables are available at
the following link:
RECORDS FOR 04-02
MAX TEMPERATURE MIN TEMPERATURE
STATION HIGH LOW HIGH LOW
------- ---------- ---------- ---------- ----------
KAVL 87 1946 41 1915 58 1945 25 1924
KCLT 86 2014 42 1901 64 1945 28 1881
KGSP 88 2012 49 1901 62 1979 26 1902
GA...Flash Flood Watch from 8 AM EDT Wednesday through Wednesday
evening for GAZ010-017.
NC...Flash Flood Watch from 8 AM EDT Wednesday through Wednesday
evening for NCZ051-052-058-059-062>065.
SC...Flash Flood Watch from 8 AM EDT Wednesday through Wednesday
evening for SCZ001>003.
Area Forecast Discussion
National Weather Service Lake Charles LA
1015 PM CDT Tue Mar 30 2021
Current forecast is largely on target, with warm and moist air
continuing to stream northward out of the Gulf, and earlier
shower/TSTM activity lifting well off to the north. Made some
minor adjustments to first period grids to nudge them toward
observational trends, namely to bring patchy fog to the coastal
waters sooner, and to slightly bump up dewpoints and temperatures,
which also resulted in a bit of a raise to forecast lows. This
warm and muggy weather will stick around into tomorrow morning,
with most areas seeing their high temperatures for the day prior
to noon as a strong cold front pushes through the region.
Wind related watches/advisories left as is, with the Gale Watch
likely to be updated to a warning by the next crew. Wind
advisories will also need to be considered, especially along/S of
.PREV DISCUSSION... /issued 649 PM CDT Tue Mar 30 2021/
00Z 31MAR21 TAFs
With exception to a few showers and isolated tstorms (mainly in
the northern part of the area), activity has been relatively calm.
Current VFR to MVFR cigs to drop tonight ahead / along of a cold
front set to sweep through starting early tomorrow. Before the
front, patchy fog at the southern terminals will cause reduced
vis. A combination of the fog and lower cigs will have the TAF
sites experiencing IFR conditions, but a few sites are flirting
with LIFR conditions around the time of frontal passage. Behind
the front, gusty northerly winds will develop and extend into the
evening hours. Near the end of the this TAF period, conditions
will begin to improve at KAEX with further improvements for the
southern terminals at the end of the next TAF period.
PREV DISCUSSION... /issued 340 PM CDT Tue Mar 30 2021/
Warm frontal boundary has quickly lifted north, ushering abundant
moisture into the region once more along with somewhat gusty
southerly winds. Additionally, radar showing scattered showers
sliding through... No lightning noted yet, but enough instability
is present that a few thunderstorms certainly cannot be ruled out
before activity exits the area late this evening. Winds relax a
bit overnight, and given the very moist airmass, some patchy fog
development will be possible after midnight.
After a relative lull in precipitation overnight, chances increase
from daybreak onward as a cold front approaches from the north. In
regards to timing, the front will push into central LA / east TX
by around daybreak to mid-morning, and then into southeast TX /
southwest LA / south-central LA by late morning to early
afternoon. Some pre-frontal showers and thunderstorms will be
possible, but the best chances look to manifest with the frontal
passage itself. Hi-res CAMs suggest the formation of a convective
line along the front, with some lingering post-frontal showers
continuing into the afternoon and early evening. The convective
line will at least pose a lower end (categorical 1/5) Marginal
Risk of severe weather. 18z HRRR analysis of the environment
shows MUCAPE on the order of 1500-2500 J/kg with modest low and
mid level lapse rates, as well as effective shear around 30 kts or
so. As such, damaging wind gusts in stronger sustained convective
cells along the line would be the primary threat, along with
potentially some scattered large hail. While the main severe
threat will end following the passage of the cold front, a tight
pressure gradient and fairly rapid pressure rises will result in
quite gusty post-frontal northerly winds. While holding off in
this forecast package, a Wind Advisory may be needed for a portion
of the forecast area to account for this. Additionally, the
strong CAA will lead to temperatures tumbling quickly downward
Any remaining precipitation is expected to taper off, and winds
will begin to relax slightly overnight into Thursday. Along with
clearing skies, forecast lows by Thursday morning range from the
mid to low 40s along and south of the I-10 corridor to as low as
the mid to upper 30s in portions of central LA. If winds do manage
to relax enough, some patchy frost will be possible in the cooler
Cooler and drier weather sticks around for the end of the work
week, with a moderating trend over the weekend and into the start
of next week. Fairly large differences in the global models to
start next week though, with the ECMWF remaining dry, and GFS
reintroducing higher PoPs as a shortwave slides through. For now,
leaned more on the drier ECMWF/NBM solutions.
A few isolated showers possible today with onshore flow around 10
to 15 kts. Onshore flow becomes lighter overnight into early
Wednesday as a cold front advances towards the Gulf. Showers and
thunderstorm coverage will increase as the front passes with
strong northerly flow developing behind it. Precipitation clears
up by Wednesday evening, but strong sustained winds with frequent
gusts to Gale Force are expected in the coastal and outer waters
through at least Thursday morning. The strong offshore flow will
also be present in Calcasieu Lake and Sabine Lake, but with winds
and gusts more likely to remain in Small Craft Advisory criteria.
A lighter but still moderate offshore flow persists thereafter
Thursday into Friday, finally relaxing and becoming more easterly
by Friday afternoon and into the weekend.
.PRELIMINARY POINT TEMPS/POPS...
AEX 69 74 37 62 / 30 80 10 0
LCH 70 76 43 64 / 20 80 10 0
LFT 71 78 43 61 / 20 80 10 0
BPT 70 76 42 66 / 20 80 10 0
GM...Gale Watch from Wednesday afternoon through Thursday morning for
Small Craft Advisory from 3 PM Wednesday to 5 AM CDT Thursday
Area Forecast Discussion
National Weather Service Louisville KY
855 PM EDT Tue Mar 30 2021
Updated at 855 PM EDT Tue Mar 31 2021
Evening surface analysis showed a cold front extending from near
Chicago IL down through St. Louis to just east of Springfield, MO.
Cloudy skies were noted across the region and area radars showed the
front edge of rain shower activity pushing east of the I-65
corridor. Temperatures this evening ranged from the upper 60s east
of I-65 in the rain free areas. West of I-65, temps have cooled off
into the upper 50s to around 60.
In the short term, we expect this rain shield to continue to push
eastward. It should get into the Lexington metro area between 10-11
PM or so. Have not seen much in the way of lightning with this
activity. This isn`t surprising after looking at the HRRR model
soundings which show very little in the way of instability at the
surface or aloft across the region.
As the surface front makes its way eastward tonight, we believe
convective coverage will expand a bit more and become a little
heavier given the low-level jet pushing into the region and
associated frontal forcing. Model soundings do show a gradient of
elevated instability across southern KY and current thinking is that
best chances of any thunder would be south of the Western KY and
Bluegrass Parkways. Cold front will slice through the region
overnight and bring an end to the precipitation from west to east.
After the frontal passage, winds will pick up out of the northwest
and are expected to be quite gusty in the post frontal wake. These
gusty northwest winds will continue into the morning hours on
Wednesday. Lows overnight will cool into the lower 40s over our
northwest sections, with 45-50 degree readings for areas east of I-
Current forecast has all this in hand, but will do a quick refresh
of the short term grids to blend current obs into the forecast
package. Updates available shortly.
.Short Term...(This evening through Wednesday)
Issued at 245 PM EDT Tue Mar 30 2021
...Warm and Breezy This Afternoon...
...Rainy Tonight and Cooler Wednesday...
Strong SSW flow in place this afternoon ahead of a low pressure
system just off to the west. The column remains dry for now, so
plenty of sunshine teaming up with the southerly wind component to
push temps into the 70s. A plume of deep moisture is making its way
up the Mississippi River Valley, currently nosing into the Memphis
metro. This warm conveyor belt/LLJ axis currently has 850 mb winds
around 35-40 kts.
Large upper level trough will continue eastward across the Upper
Midwest tonight into tomorrow. The area of deep moisture and nose of
the strongest moisture transport off to the southwest will reach the
western CWA by 00z this evening. Narrow LLJ core does increase to
around 50 kts over central KY between 04-06z, coinciding with the
strongest integrated water vapor transport. A plume of 1.2 to 1.5 PW
values will spread eastward into the area just ahead of the sfc cold
front, but the front is generally progressive in nature. Flash
flooding looks unlikely, but minor nuisance flooding and typical
ponding/pooling of water in low spots can be expected.
A band of showers and isolated storms will then work east across the
area between 00-12z Wed, with thunder chances mainly in central KY
with the best chance for a storm in southern KY. Gusty showers look
possible, but the severe weather threat is limited due to weak (and
mainly elevated) instability.
The front pushes through between 06-12z, and winds abruptly veer NW
behind the front and cooler air floods the region. Temps will be
dropping through the 40s and 50s Wed morning, and breezy/wet
conditions will make for an unpleasant day. Scattered post-frontal
light rain showers will remain possible into the afternoon,
especially east of I-65. Total rainfall amounts through Wednesday
will range from 0.30-1.25 inches, with the higher 1+ inch totals
likely in south-central KY.
.Long Term...(Wednesday night through Tuesday)
Issued at 237 PM EDT Tue Mar 30 2021
...Hard Freeze Expected Thursday and Friday Morning...
Few showers may linger behind the departing system across the
Bluegrass and our eastern CWA Wednesday evening as an upper level
trough moves across the Ohio Valley. As the flow turns more
northwest aloft, drier and and colder air will advect in across the
region as a strong 1035mb surface high builds in and expands across
the Central Plains and Ohio Valley Thursday into Friday. This will
bring unseasonably cold temperatures to the region for the end of
the week. With this cold regime in place, we will be going with a
freeze warning for Thursday morning and a freeze watch for Friday
morning. Both mornings feature many hours below freezing (25 to 30F
Thursday morning and 20-25F Friday) with Friday featuring a hard
freeze with several hours at or below 25F. Friday morning lows could
possibly be record-breaking and the coldest morning as the surface
high will be sitting directly over us. As for afternoon highs,
temperatures will range 15 to 20 degrees below normal on Thursday
(40-45F) and 10 to 15 degrees below normal on Friday (46-51F).
The rest of the period features lots of dry conditions, sunshine and
warming temperatures. With surface high pressure anchored off the
southeastern US and ridging aloft. Highs will be back in the 70s
Sunday through the start of next week.
.Aviation...(00Z TAF Issuance)
Issued at 658 PM EDT Tue Mar 30 2021
IMPACTS: Gusty southwest winds will continue this evening. Line of
showers to impact the TAF sites through the period. Thunderstorm
chances highest at KBWG, likely no thunderstorms at KHNB/KSDF/KLEX.
Wind shift behind frontal boundary expected overnight with gusty
winds in the wake of the front.
DISCUSSION: Gusty southwest winds will continue this evening at the
terminals, though not as windy as this afternoon. Line of showers
will move into KBWG/KSDF/KHNB shortly after 31/00Z with MVFR to VFR
vsbys and VFR cigs. More convective development is expected after
31/03Z though rain showers are expected at KHNB/KSDF/KLEX but will
carry VCTS for a period down at KBWG where better elevated
instability is progged to be. Frontal boundary comes through
overnight with wind shifts at KHNB around 31/06-07Z, KSDF/KBWG 31/08-
10Z, and KLEX 31/11-12Z. We expect a period of gusty winds, perhaps
20-25kt gusts right behind the front and lasting a few hours. We
expect stiff northwest winds to continue through the day on
CONFIDENCE: Medium-High confidence forecast on all elements.
IN...Freeze Watch from Thursday evening through Friday morning for
Freeze Warning from 2 AM EDT /1 AM CDT/ to 11 AM EDT /10 AM CDT/
Thursday for INZ076>079-083-084-089>092.
KY...Freeze Watch from Thursday evening through Friday morning for
Freeze Warning from 2 AM EDT /1 AM CDT/ to 11 AM EDT /10 AM CDT/
Thursday for KYZ023>043-045>049-053>057-061>067-070>078-081-
Area Forecast Discussion
National Weather Service Memphis TN
1017 PM CDT Tue Mar 30 2021
Showers and thunderstorms continue to move through West Tennessee
and North Mississippi. The line that has developed is ahead of
pre-frontal trough. The main cold front has pushed through West
Plains, Missouri and Mountain Home, Arkansas. The front should be
pushing into Northeast Arkansas by midnight. The 00Z HRRR shows
some redevelopment of showers ahead of the front as it pushes into
Northeast Arkansas. Thunderstorms will likely occur along the
front as it approaches the Mississippi River. Can`t rule out a few
storms becoming strong to severe, but main threat will be from
flash flooding especially east of the Mississippi River. Current
forecast has a good handle. No updates are expected.
.DISCUSSION.../issued 345 PM CDT Tue Mar 30 2021/
Water vapor analysis indicates an upper-level jet streak moving
across the Ozarks this afternoon. This jet is located just
downstream of a deep trough over the central CONUS. Southerly
winds have increased across the CWA with dewpoints mainly in the
40s and 50s. However, the juicier air is right on the doorstep
with dewpoints in the mid/upper 60s just to our south. Large scale
ascent will continue to increase across the Mid-South overnight
as this trough approaches. Deep warm advection will promote the
development of additional showers and thunderstorms across the
Instability is beginning to nose into the Mid-South across the
delta with MUCAPE near 500 J/kg. We did see a few lightning
strikes in the Memphis area over the past hour to corroborate the
mesoanalysis. Short-term model progs continue to increase
instability this evening into the early morning hours, albeit
only into the 500-1000 J/kg range. Deep-layer shear is weaker than
we have seen in recent events but is still likely strong enough
to help maintain organized storms throughout the night.
Precipitable water is approaching 1.5" across the area and there
is a potential for some training convection overnight. Given this
threat and the antecedent soil conditions, a Flash Flood Watch was
issued for areas mainly south of I-40 and east of I-55.
Widespread amounts of 1-2" are expected with localized higher
amounts. HREF probability matched mean fields suggest pockets of
3-4" are possible.
A cold front will move across the area overnight, pushing the
moist, unstable air back to the south. Storms are expected to
line up along this boundary but shear vectors are largely parallel
to the boundary and should limit the intensity of this line. That
said, some damaging wind gust are possible, as is a brief spin-up
should any kinks develop within the line. Some elevated shower
activity will continue through the morning hours as the trough
axis moves across the area, but additional rainfall by this time
will remain generally light.
Dry weather is expected Wednesday night through early next week as
a ridge translates across the central CONUS. Temperatures will
be well below normal for early April and frost/freeze conditions
are likely. A light freeze (and widespread frost) is expected
Thursday morning with a more widespread freeze expected Friday
morning. Some areas will likely experience a hard freeze during
this time. A Freeze Watch or Warning will likely be issued
tonight. Otherwise, expect moderating temperatures over the
weekend with 70s returning by early next week. The next chance of
rain doesn`t look to come into play until perhaps Tuesday.
SHRAs and a few TSRAs will push through the region tonight. Flying
conds will continue to deteriorate with widespread MVFR ocnl IFR
overnight. Most of the SHRA/TSRA will stay SE of KJBR. Best
chances of TSRA at KMEM/KMKL will occur over the next few hours
and perhaps as late as 08z. KTUP will run a little later...mainly
from 06z-10z. Expect LLWS in advance of the front this evening. South
winds around 10 kts will shift to NW at 10-15 kts with the cold
frontal passage overnight and become gusty. Expect conds to start
improving from the NW then N late tonight into Wednesday with VFR
conds returning by mid morning. Expect some SHRAs to move across
the area on Wednesday as an upper level disturbance moves through.
MS...Flash Flood Watch through Wednesday morning for Alcorn-Benton MS-
TN...Flash Flood Watch through Wednesday morning for Benton TN-
Area Forecast Discussion
National Weather Service Pueblo CO
707 PM MDT Tue Mar 30 2021
Issued at 701 PM MDT Tue Mar 30 2021
Updated to expire the Red Flag Warning at 7 PM as winds are
subsiding and humidity values recovering across the San Luis
UPDATE Issued at 550 PM MDT Tue Mar 30 2021
Updated to adjust precipitation chances for this evening across
the Plains based on the latest model guidance. This included
trending down pops by midnight. Rain and snow is spotty, mainly
over the Palmer Divide, and a couple of bands along Highway 50
across Otero, Bent and Prowers Counties. Elsewhere, light
precipitation is possible, but will not amount to much. Mozley
.SHORT TERM...(This evening through Wednesday)
Issued at 259 PM MDT Tue Mar 30 2021
There generally have been minimal impacts today in areas where snow
has been falling, with areas that have seen accumulation, mainly
just seeing it on grassy areas. In general, the low levels of the
atmosphere remain fairly dry, and there have been a lot of virga
over portions of the I-25 corridor south of Colorado Springs. In the
San Luis Valley winds have been very strong this afternoon and the
humidity is very low, creating high fire danger. Will keep the Red
Flag Warning for the San Luis Valley in effect through 7 PM.
Tonight an upper trof over the area will be slowly working its way
eastward. The NAM and HRRR show little in the way of precip over
the area, while the GFS had a bit more. Will keep isolated to
scattered showers, mainly over the eastern mtns and plains through
the evening and maybe a little past midnight in some area, but it
doesn`t look like they should amount to much. Over eastern areas,
clearing skies area expected later tonight, and temps over southern
CO are expected to be below average, with teens and lower 20s over
most of the lower elevations, including the high valleys.
On Wed, dry northwest flow aloft will be in place over the region as
the upper trof moves east of CO. Temps on Wed will be warmer over
the plains, with highs in the upper 40s to mid 50s. In the San Luis
Valley and Upper Arkansas River Valley highs should be in the upper
40s and lower 50s.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 259 PM MDT Tue Mar 30 2021
Wednesday night through Thursday...
The ridge is going to continue to strengthen with warmer
temperatures over all of the CWA by Thursday afternoon. Much drier
conditions can be expected over the plains in general. For the
southeastern plains, especially for Baca County, will need to be
monitored for possible critical fire weather conditions as RH values
get down below 15% during the afternoon and winds pick up to become
strong and gusty out of the southwest. Low temperatures will also
return to more seasonal values for this time of year.
Thursday night through Saturday...
Ridge will even further strengthen with very warm temperatures over
the plains. There will be an upper level disturbance moving in from
the southwestern US which will help to destabilize the mid and upper
levels and possibly provide a chance of showers and thunderstorms,
and even some high elevation show showers over the southern
mountains and possibly over the Raton Mesa region as well later in
the night on Thursday. This U/L low will propagate out of the CWA by
later in the day on Saturday with possibly only a few remaining
showers and/or thunderstorms developing over the San Juans and
southern Sangres Saturday afternoon. The ensembles have a general
consensus of the timing of this, while the deterministic models
differ a little more, with the ECMWF having the propagation of
this U/L trough to be a little slower than the GFS. The long wave
ridge will still be building in over the entire region and
allowing for very warm temperatures to set in over the plains for
Saturday, well above the seasonal average.
Saturday night through Sunday night...
The ridge is going to be at its strongest over the region on Sunday,
with possibly record-breaking temperatures for the plains. Some mid
to upper level moisture moving in from the southwest ahead of the
next trough, along with minor instability, could allow for some
thunderstorms to develop during the afternoon over the central
mountains, while the rest of the CWA remains dry. Also for Sunday
afternoon, the southeastern plains will again need to be monitored
for possible critical fire weather conditions due to strong and
gusty southeasterly winds, coupled with dry and very warm
Monday through Tuesday...
The ridge is going to break down as an approaching major shortwave
trough begins to impact the region. There will be some moisture
ahead of this trough which could allow for even the plains to be
able to finally get some precipitation as well, mainly in the form
of rain. Snow will be likely over the higher elevations on Tuesday,
although models due tend to differ with the exact timing and amount
of QPF due to the fact that it is still very far out and the models
are not very reliable at this moment. However, there is a general
agreement that there will be a low pressure system affecting the
region around this time in the forecast period.
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 259 PM MDT Tue Mar 30 2021
It looks like VFR conditions can be expected at KCOS, KPUB and KALS
the next 24 hrs. There could be some showers at or in the vicinity
of KCOS and KPUB through the evening, then decreasing clouds are
expected late tonight. KALS is expected to have gusty westerly
winds into the early evening and then they should decrease.
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
1107 PM EDT Tue Mar 30 2021
1 Hour RAP forecast valid at 03Z shows a broad swath of lingering
0-1km MLCAPE of around 650 J/kg across Hillsborough/Polk and near
800-1000 J/kg towards Sarasota/Charlotte counties. A subtle piece
of mid-level vorticity moving across the Peninsula is aiding to
some nocturnal showers across the area. Have bumped up PoPs to
reflect this as coverage may continue to increase through the
.Preliminary Point Temps/PoPs...
TPA 72 86 69 76 / 40 20 10 20
FMY 70 89 70 83 / 40 30 20 20
GIF 70 89 68 78 / 50 40 60 30
SRQ 70 85 68 77 / 40 10 10 20
BKV 65 89 61 75 / 40 30 10 10
SPG 72 84 70 75 / 40 10 10 20