Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/08/20
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
910 PM CDT Sun Jun 7 2020
Issued at 910 PM CDT Sun Jun 7 2020
Showers and thunderstorms, some severe, were lifting northeast
across the cwa this evening. These will be lifting into north
dakota tonight. Made adjustments to pops earlier.
UPDATE Issued at 650 PM CDT Sun Jun 7 2020
00z aviation discussion updated below.
.SHORT TERM...(This Evening through Monday Night)
Issued at 320 PM CDT Sun Jun 7 2020
Main concern in the near term is the potential for strong to severe
thunderstorms late this afternoon and this evening as a cold front
tracks across the area and encounter extreme instability. CAPE
values of 3000-5000 J/kg will be common late this afternoon into the
early evening hours. Bulk shear will increase into the 50 to 65 knot
range along and ahead of the front, along with a low level jet
increasing into the 50 to 70 knot range. This combination of factors
will result in thunderstorm development, which looks to initiate
around 22Z between the Missouri River and the James River Valley.
The biggest question right now is whether these storms will take
more of a northeast track as shown in the HRRR and the ARW, or if
they line out and more more easterly as shown by the high resolution
NAM and the NMM. There will be a bit of a stronger CAP over the
southeastern part of the CWA, so for now, will lean toward the more
northeasterly track solution and keep fairly low POPs across the
east. Where the storms do develop, conditions will be highly
favorable for them to go severe, with gusty winds and large hail the
most likely threats. An isolated tornado or two cannot be ruled out
due to the strong shear as well. May see some lingering showers
across the far northeastern part of the CWA into the overnight
The frontal boundary stalls out over the far eastern CWA on Monday,
but conditions during the day will be mainly dry with little else to
support precipitation. By Monday night however, an upper trough will
approach the region and will begin to meet up with the remnants of
Tropical Storm Cristobal, and the stalled front looks to then become
the focus for rainfall. The uncertain part now is just how far west
this precipitation will reach, with some models keeping it east of
the James River Valley, and others bringing it as far west as the
Leola Hills region. Rainfall amounts in excess of 1 to 1.5 inches
cannot be ruled out.
Low temperatures tonight will range from the upper 50s northwest to
the lower 70s east, with highs on Monday ranging from the mid 70s
northwest to the lower 90s east. Lows Monday night will be in the
.LONG TERM...(Tuesday through Sunday)
Issued at 320 PM CDT Sun Jun 7 2020
The period begins on Tuesday with the remnant tropical system surging
northwards into the Midwest. The storm system, along with a mid
level trough passing through the region will bring showers and
thunderstorms to the eastern half of the CWA. With a more stable
environment, severe weather is not expected on Tuesday.
Cooler, dry air will move into the region on Wednesday with boundary
layer dew points in the mid 40s. The combination of steep low level
lapse rates and some mid level moisture may result in isolated
showers, mainly in the eastern CWA. Buffer soundings support gusty
winds on Wednesday with a max gust of 30 to 35 knots. The rest of
the long term will feature dry conditions with temperatures below,
to near normal. Temperatures will be around normal on Saturday and
Sunday with highs in the upper 70s, to the low 80s.
.AVIATION...(For the 00Z TAFS through 00Z Monday Evening)
Issued at 650 PM CDT Sun Jun 7 2020
Thunderstorms are expected to move from southwest to northeast
across the region into the early morning hours. PIR and ABR are
expected to be affected with possible MVFR vsbys and ceilings.
Otherwise, expect VFR conditions for ATY and MBG for the entire
period and after the storms pass, expect VFR conditions at ABR and
***Construction to improve the taxiway for runway 13 at the KPIR
terminal may cause an occasional temporary visibility reduction due
to blowing dust (bldu), mainly during daytime hours UFN.
Area Forecast Discussion...Updated
National Weather Service Billings MT
839 PM MDT Sun Jun 7 2020
Thunderstorm activity decreasing in intensity across the area and
areas of stratiform precipitation beginning to fill in across
south central Montana. Updated forecast to decrease thunderstorm
Tonight through Monday night...
Early this afternoon have started to see some thunderstorm
development in the western zones. There have been some winds with
these thunderstorms, but nothing of concern at the moment. The
HRRR has not been as aggressive with the 80m winds as it had been
on previous runs. However, still expecting strong winds to be the
main threat. There could also be some hail, have already had a
report of some pea-sized hail in the Beartooth Foothills. These
storms should quickly move off through the evening.
Overnight and through Monday night, still expecting the mountains
to see some accumulating snowfall. Generally this will be above
6000 feet with the highest accumulations of over 6 inches above
8000 feet. This will still impact the Beartooth Pass. The rest of
the area will see showers become scattered through the day.
Temperatures will be cooler than normal for the whole area. Reimer
Tuesday through Sunday...
Weak shortwave in northwest flow aloft should have enough forcing
for light mainly diurnal showers on Tuesday, especially in the
east where coldest air aloft will be in the afternoon, though
otherwise we will see drying on this day with precipitable waters
falling under a half inch. W-NW winds will be well-mixed and
breezy. Look for temps in the 60s.
Building ridge from the west will bring a warmer and mostly dry
day on Wednesday, but there may yet be enough energy for a few
showers over the mountains/foothills. W-NW winds will again be
Expect amplified ridge to bring warmer conditions Thursday through
Saturday, with temps returning to the 80s if not lower 90s by the
end of the week. As the ridge axis shifts east, southwest flow
aloft and increasing high plains moisture will open the door to
thunderstorm potential by the weekend. A deeper trof is possible
by next Sunday or Monday, but plenty of model uncertainty this far
Areas of rain showers across the region with periods of MVFR
along the foothills and mountain obscurations. KLVM and KSHR
terminal sites with best odds of seeing MVFR. A few isolated
thunderstorms possible. borsum
.PRELIMINARY POINT TEMP/POPS...
Mon Tue Wed Thu Fri Sat Sun
BIL 046/060 044/067 049/072 049/080 054/086 058/085 057/079
97/W 32/W 01/B 00/U 00/B 11/B 23/T
LVM 041/055 036/064 045/070 044/079 049/084 053/082 051/073
79/T 40/N 12/T 00/U 01/B 12/T 34/T
HDN 046/062 044/067 047/072 047/080 052/089 058/088 058/082
95/W 32/W 01/B 00/U 00/U 01/B 22/T
MLS 050/063 046/065 047/070 048/078 052/085 060/085 059/082
94/W 32/W 00/N 00/U 00/U 11/B 22/T
4BQ 048/066 045/064 045/070 047/078 050/086 058/088 057/082
83/W 32/W 00/N 00/U 00/U 01/B 22/T
BHK 049/066 044/064 044/069 046/076 048/081 055/082 055/078
72/W 22/W 00/N 00/U 00/U 01/N 22/T
SHR 043/064 041/064 042/071 044/078 049/087 056/088 055/081
84/T 42/W 01/B 00/U 00/U 01/B 22/T
MT...Winter Weather Advisory in effect until noon MDT Monday for
the Beartooth Highway FOR ZONE 67.
AREA FORECAST DISCUSSION
National Weather Service Hastings NE
1012 PM CDT Sun Jun 7 2020
...Short Term Update...
Issued at 1012 PM CDT Sun Jun 7 2020
Will defer to oncoming overnight shift to dig into this much
deeper and make necessary forecast adjustments, but general trend
from some of the latest 00Z models (especially HRRR/NAM12)
suggests that the incoming frontal boundary could be slowing
enough to focus the vast majority of any Monday late afternoon-
evening severe storm potential almost completely to the northwest
of our CWA, with the main focus clearly over the WFO LBF domain.
Other models still show some pre-sunset potential in our western-
northwest counties, so this is not a "sure thing". However, if
this slower trend looks to continue, then our overall severe storm
messaging for Monday in our HWO/graphics etc. may need to undergo
some somewhat-notable changes. Will be interesting to also see if
the upcoming Day 1 SPC outlook perhaps trends northwest a bit
from the current Day 2 configuration.
UPDATE Issued at 556 PM CDT Sun Jun 7 2020
Within the past hour, have updated our routine forecast products
and Hazardous Weather Outlook (HWOGID) mainly to address the
- Strong south winds:
Winds today ended up being a bit stronger than expected
(especially from our forecast of 24 hrs ago), with numerous
official/unofficial stations reporting peak gusts in the 45-55 MPH
range, and even a few sites (including Ord airport) falling BARELY
shy of official High Wind Warning criteria with a 57 MPH gust.
Although we have opted against a formal/short-fuse High Wind
Warning in our western counties given that the likelihood of
anything more than a rogue/isolated 58+ MPH gust seems quite low
from here on out, the HWO text was beefed up to reflect the
potential for "near-severe" gusts up to around 55 MPH. Although it
will remain noticeably breezy/windy right on through the night
with gusts commonly 30+ MPH even past midnight, the potential for
widespread strong gusts of 45+ MPH should drop off near/after
- Patchy blowing dust:
Going hand in hand with the strong winds, we have heard of at
least patchy blowing dust/reduced visibility today within our
coverage area (CWA) this afternoon, especially near open/recently-
worked fields. While very localized areas could certainly be
experiencing greatly-reduced visibility, we have opted against a
formal Blowing Dust Advisory due to the fact that visibility
issues/impacts do not seem very widespread. However, have added
"patchy blowing dust" to the routine forecast CWA-wide through 10
PM, and also introduced a mention of potential visibility
reductions in blowing dust to our HWO.
.SHORT TERM...(This evening through Monday)
Issued at 302 PM CDT Sun Jun 7 2020
Main issue in the short term will be timing of possible precip for
Cirrus stuck around a bit longer during the day today and did seem
to knock temps down a tad. Some ACCAS showing up on satellite, and
I would not be surprised if we got a sprinkle or two from these
high based features. Not much consequence from these.
Another night of warm air advection, with a breeze, with some
For Monday, the cold front approaches slowly from the northwest,
and our temperatures should boost into the 90s once again for
highs. Could be some compressional warming just ahead of the
front, but some mid-level sky cover could help to tamp temps from
full potential. Wide display from models for timing, placement,
and amount of precip. The experimental HRRR is clearly the outlier
for how slow the cold front/precip makes it to the east, and
pretty much holds off on our CWA from getting precip into
overnight Monday night. The rest of the models are more liberal
with eastward progress, and as I think that the experimental HRRR
could be on to something, especially considering Cristobal heading
north from the Gulf, I cannot completely buy into it. I did take a
bit of a compromise there.
.LONG TERM...(Monday night through Sunday)
Issued at 302 PM CDT Sun Jun 7 2020
We could get some training of cells develop by Monday night,
especially our northern CWA where better support will be. It is
actually looking like a better chance of localized flooding may be
toward Tuesday in the post-frontal regime with elevated
convection. I expect quite a bit of wind with strong cold air
advection, socked in with stratus and plenty of rain. Elevated
convection could push the already strong wind gusts to close to 50
mph, perhaps. Temps may struggle to hit 70s for much of the CWA. I
went closer to CONSMOS wind speeds over the initialized NBM with
the anomalously strong cold air advection for this time of year.
As far as severe potential for Saturday afternoon/evening. Severe
parameters certainly support any convection that develops along
and ahead of the front. The limiting factor for us will be timing.
By the time much of the convection reaches our CWA, much of the
severe potential will likely decrease, turning the main hazard
into isolated/localized flooding later into Monday night.
By Wednesday we finally dry out behind the front and upper level
ridging should warm us up by late in the long term, especially
toward the weekend, and perhaps a bit more than our forecast.
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday)
Issued at 721 PM CDT Sun Jun 7 2020
Although there is the slightest chance of thunderstorm activity
trying to get underway toward the extreme end of this valid period
(around 00Z Tuesday), this is actually a fairly high-confidence
forecast regarding expected dry weather/VFR visibility, and
medium-high confidence forecast for VFR ceiling. Overall, the
greatest aviation issue remains strong southerly winds, both at
the surface and slightly above it, with low level wind shear
(LLWS) developing again overnight. Read on for more element-
Winds (including LLWS):
At the surface, especially these first 6-9 hours will be fairly
windy, with southerly sustained speeds commonly 25-30KT/gusts
35-40KT. Although still quite breezy, speeds during the latter
half of the period will tone down a bit, with sustained southerly
speeds averaging closer to 20KT/gusts mainly under 30KT. As for
LLWS tonight, although the actual magnitude of shear will be
somewhat modest (around 30KT) due to the continued gusty surface
winds, a formal LLWS inclusion is certainly justified given that
speeds within roughly the lowest 1,500 ft. will average a solid
50-55KT from the south, especially during the 03-12Z time frame.
Although have maintained VFR throughout (and with high confidence
through at least the first 12 hours), there are hints that a low-
end VFR ceiling (perhaps flirting with high-end MVFR briefly)
could materialize at times especially Monday afternoon, so this
Area Forecast Discussion
National Weather Service North Platte NE
623 PM CDT Sun Jun 7 2020
Issued at 351 PM CDT Sun Jun 7 2020
Wind gusts to around 60 miles per hour have occurred at Imperial,
North Platte and Broken Bow. This is about 10 mph faster than the
HRRR model predicted this morning. Strong gusts should continue to
sunset and a high wind warning is now in effect for parts of
southwest and central Nebraska.
.SHORT TERM...(This evening through Monday night)
Issued at 327 PM CDT Sun Jun 7 2020
A reasonably strong cap is in place this afternoon across wrn and
ncntl Nebraska but a few of the CAMs indicate a brief but intense
period of storm development late this afternoon. With the loss of
daytime heating this evening, the cap will strengthen and the models
show the storms quickly dissipating. SPC asked for a 20z LBF upper
air sounding to determine the strength of the cap which would
dictate the potential for severe weather. If any of the vaulting
towers this afternoon can build down through the cap layer and tap
into the boundary layer moisture, 50kt winds at h500mb and MLCAPE
between 2500 and 3000J/KG would support supercells.
No other convection is expected tonight or Monday morning.
An anomalous upper low featuring -30C temperatures at h500mb has
moved into the Pacific Northwest. The upper low will move east
tonight and drive a Pacific cold front into cntl Nebraska Monday
afternoon. The front and the upper low will be the basis for a
combined severe weather/flood threat late Monday afternoon through
Tuesday morning affecting the eastern Sandhills, southwest and ncntl
Nebraska. Precipitable water in the models increases to between 1.5
and 2.0 inches supporting the heavy rain threat which will occur
along and north of the front. The models show about a 50 mile wide
swath of heavy rain behind the front Monday night with totals around
WPC suggested slow moving storms, warm cloud precipitation
processes, storm training and back building will contribute to the
flood threat Monday night. Along and ahead of the front, SPC
suggested a tornado threat late Monday afternoon and Monday evening.
Wind damage and large hail would be possible west or behind the
front. A flood watch is in place for Custer county Monday night.
Recent heavy rainfall in this area has pushed 3-hr flood guidance
below 2 inches in many areas.
The location of the front, which could be as far east as Norfolk to
McCook or as far west as Imperial to O`Neill, will dictate the
location of the tornado threats and there is about a 50 or 70 mile
spread in the models east and west with the location of the highest
.LONG TERM...(Tuesday through Sunday)
Issued at 327 PM CDT Sun Jun 7 2020
An upper level trof will move across wrn and ncntl Nebraska
Tuesday. Moisture wrapped around a closed h700mb low moving through
Nebraska is the basis for ocassional showers throughout the day. The
h700mb low and the moisture will exit the region Tuesday night. Dry
weather is in place Wednesday through Saturday.
The models are in reasonably good agreement showing another upper
low/trof moving through the wrn U.S. next Sunday. This would be the
next chance for thunderstorm development.
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 623 PM CDT Sun Jun 7 2020
Wind is the primary aviation weather concern for western and north
central Nebraska. Strong southerly winds will continue to gust
frequently around 40 kts through sundown, then slowly decrease
overnight to where most gusts should subside by 08/12z. However,
low level wind shear conditions arise with a 55+ kt southerly jet
at 2kft. A cool front begins to work through the region Monday
morning, resulting in a wind shift to northwesterly and some gusts
above 20 kts again during the afternoon. Another concern,
primarily this evening, is scattered thunderstorms in the
panhandle and western Sandhills. Brief drops in cigs/visby, along
with erratic wind gusts, are possible at KGRN, KVTN, KTIF.
High Wind Warning until 9 PM CDT /8 PM MDT/ this evening for
Flood Watch from Monday evening through Tuesday morning for
Area Forecast Discussion...UPDATED
National Weather Service Miami FL
838 PM EDT Sun Jun 7 2020
High pressure continues to build into the Florida Peninsula from
the Atlantic waters this evening, as Tropical Storm Cristobal
continues to move northward through Louisiana. The high will
continue to build into the Florida Peninsula tonight bringing in
drier air to the region. Therefore, POPs have been removed from
most of South Florida for tonight, except for the east coast areas
where a few showers could work into this region from the Atlantic
waters late tonight on the easterly wind flow.
The threat of rip currents have also decreased along the east
coast beaches of South Florida this evening, as the wind speeds
have fallen below 15 mph. The wind speeds will continue to slowly
decrease through the night hours tonight. Therefore, the High Risk
of Rip Currents along the east coast beaches of South Florida has
been allowed to expire. However, the threat of rip currents will
continue along with the coastal flood statement for the west coast
beaches of South Florida tonight, due to the westerly swells from
Tropical Storm Cristobal.
Rest of the forecast looks good at this time and no other changes
The winds will remain easterly around 5 to 10 mph tonight over all
of the TAF sites with mostly dry conditions. There could be a
shower or two over the east coast taf sites late tonight into
early Monday morning, but the coverage will be few and far between
to put it in the east coast TAF sites at this time. The ceiling
and vis will also remain in VFR conditions over all of the TAF
.Prev Discussion... /issued 327 PM EDT Sun Jun 7 2020/
Short Term (Rest of Today-Monday)...
Previous Mesoscale Discussion for highly conditional convective
potential for this afternoon:
There is a conditional risk of a few strong to locally severe
thunderstorms developing across portions of South Florida this
afternoon into the early evening hours. At this time, it appears
that afternoon convection could initiate somewhere across the
southern Everglades of South Florida by the early to mid afternoon
hours where pockets of cloud clear/thinning are evident in GOES-16
visible imagery loops and horizontal convective rolls (HCRs) are
developing. If convection can initiate and withstand the negative
effects of enhanced dry-air entrainment in association with an
elevated mixed layer (EML) plume across the eastern portions of
South Florida, the storms will likely advect northward or
northeastward with the mean steering flow. This storm motion could
increase residence time of convection within strong surface-based
At this time, areas from the interior/Lake Okeechobee region towards
Palm Beach County may be at the greatest risk of seeing a few strong
to locally severe storms. All convective hazards will be on the
table with the more robust convection that may develop today, to
include strong to isolated damaging wind gusts, funnel clouds/brief
tornados, small hail, and lightning. Once again, these convective
hazards are referring to a reasonable-worst-case scenario and are
conditional upon the magnitude of mesoscale convergence which will
be required to trigger deep moist convection.
In the lower-levels, South Florida is under the influence of the
western periphery of Atlantic subtropical high pressure and the
outer periphery of Tropical Storm Cristobal. This is allowing for
enhanced southerly surface flow and rich boundary-layer moisture
advection (highlighted by dewpoints in the upper 70s across South
Florida). In addition to strengthening surface-based buoyancy
associated with the rich boundary-layer moisture, enhanced southerly
low- level flow is also acting to locally elongate low-level
hodographs, allowing for modest stream-wise vorticity across South
In the mid-levels, dry air has worked into the region (potentially
associated with the aforementioned EML. The EML may have advected
across the eastern portions of South Florida throughout the day
yesterday and has acted to locally steepen maximum mid-level lapse
rates to an impressive 7.7 C/km (per todays 12Z MFL RAOB). While the
dry air aloft will enhance the negative effects of dry-air-
entrainment on convective updrafts, the steep mid-level lapse rates
will allow for enhanced upward parcel accelerations in updrafts,
acting to offset the negative effects of the dry-layer aloft and
precipitation loading. The EML may be associated with a subtle
Saharan Air Layer (SAL) that was evident in GOES-16 True Color
imagery to the SE of South Florida. These mid-level lapse rates may
begin to advect out of the region through the day today, which is
being depicted in current RAP mesoscale analysis. This would greatly
reduce the risk of stronger wind gusts and hail development today.
In the upper-levels, a closed 300-200mb high pressure is situated
over Cuba. The is allowing for enhanced southwesterly to westerly
flow aloft, and helping to provide weak, albeit some synoptic ascent
in the form of differential divergence across South Florida.
Deep-layer shear is currently on the order of 25 to 30 knots, which
will help to organize convection and separate updrafts and
downdrafts. As previously mentioned, low-level shear is also
enhanced today across South Florida, highlighted by 0-3km SRH of 120
m2/s2 from todays 12Z MFL RAOB.
If 0-3 km lapse rates are able to locally steepen in association
with pockets of surface heating today and mesoscale convergence can
become enhanced, this could increase the realization of stronger
convection today. There is plenty of uncertainty regarding the
initiation and maintenance of deep moist convection this afternoon.
Any convection that does develop should diminsh after sunset with a
generally dry overnight period. A warm and muggy night across the
region with cloud cover continuing to allow temps not to cool very
As we move into Monday, mid-upper level ridging with a southeasterly
wind flow. However, overall flow will be lighter as the gradient
decreases with Cristobal weakening after landfall and continuing to
move northward. Therefore, sea breezes will be the main forcing for
convection. There is a moisture tail from TS Cristobal that allows
the mid-levels to moisten compared to todays drier air and the
presence of EML/SAL dissipated. This combination will allow allow
better coverage of storms.
Temperatures will remain in the upper 80s to low 90s, with dew
points in the upper 70s, it will feel like near 100 degrees with the
muggy humid weather continuing.
Long Term (Tuesday through end of the week)...
The aforementioned mid-upper level ridging and building sfc high
will allow flow to become more easterly as we move towards the
middle part of the week. Another surge of tropical moisture moves
into the region on Wednesday with precipitable water levels around 2
inches. Although, still a typical summertime sea breeze convective
pattern better overall coverage is expected on Wednesday, with
highest coverage over the Lake Okeechobee and interior regions given
the flow regime.
As we move towards the end of the work week we get some relief from
with some drier air moving into the mid-upper levels. A upper level
trough almost TUTT like moves in from the western Atlantic helping
to dry out the mid-upper levels as can be seen on model soundings
down to 1.5 inches or less. This will help lower overall coverage
and rain chances across South Florida as we end the work week.
High temperatures throughout the long term will generally range from
the mid to upper 80s, with low 90s across SW Florida. High humidity
will keep max heat indices in the mid to upper 90s to low-mid 100s.
Scattered showers and storms across the area the next
few days. Southerly winds will gradually become easterly as high
pressure builds across the region. Gulf marine conditions will
gradually improve as swell, seas and winds begin to diminish as
TS Cristobal makes landfall and moves north.
Aviation (18Z TAFs)...
Primarily VFR conditions expected through the TAF period.
Lingering MVFR cigs from earlier have mostly lifted. Convective
coverage remains limited so far this afternoon, though isolated
development remains possible across interior South Florida this
afternoon. Expect brief bouts of MVFR to IFR cigs/vis in and
around any of the stronger storms that may develop today.
There is a high risk of rip currents at all South Florida beaches
through this evening. A high risk of rip currents will remain at the
Gulf coast beaches through at least Monday, as swell and surf from
TS Cristobal gradually diminishes.
Coastal Flooding: With the full moon, the concern of minor coastal
flooding continues through the weekend. For the Gulf coast, swell
from Cristobal will combine with the higher-than-normal high tides
to create the potential for minor coastal flooding.
.Preliminary Point Temps/PoPs...
West Palm Beach 77 89 76 88 / 10 20 10 30
Fort Lauderdale 80 87 78 87 / 10 20 10 30
Miami 79 89 77 88 / 10 20 10 30
Naples 78 89 76 89 / 10 20 10 30
FL...High Rip Current Risk through Monday evening for FLZ069.
GM...Small Craft Advisory until 10 AM EDT Monday for GMZ656-657-676.
Area Forecast Discussion
National Weather Service Blacksburg VA
1046 PM EDT Sun Jun 7 2020
High pressure keeps the area drier with lower humidity into
Monday. As the flow turns around Tuesday look for increasing
moisture. A front arrives midweek with our next threat of
showers and storms.
.NEAR TERM /THROUGH MONDAY/...
As of 1045 PM EDT Sunday...
Temperatures still running several degrees cooler than
anticipated, so lowered them again. The overnight lows still
look good, it was mainly the hourly T grids that were just not
trending down quick enough in this currently dry surface air
In the southwest part of the CWA, small light rain showers have
been popping up in the Watauga/Wilkes county area. This has been
consistently shown by the HRRR and the NAMNest simulated radar
progs and also coincides with an area of easterly wind and
surface moisture convergence. Dewpoints transition from the
lower 60s across northern Watauga and Wilkes to the lower 70s
near the southern border of these counties. These same models
show this precipitation expanding northeastward along the Blue
Ridge overnight, but confidence in this occurring is low at this
point, but will need to be watched. Bottomline, clouds were
increased in northwest NC through the night/morning hours and
also pops were brought up to slight change for -SHRA from TNB to
MWK and UKF over the next few hours.
As of 800 PM EDT Sunday...
Only some minor tweaks to the T, Td, Pop, Sky, Wx, and Wind
grids this hour. Temps were running just a bit warmer than
anticipated, but not make any changes to the overnight lows at
this time, only the readings over the next 3-4 hours. Pops
seemed a bit high across the southwest part of the CWA leaning
toward the NAM Nest, which does not seem to be verifying well
per latest radar and satellite. There is a significant dewpoint
discontinuity near the I-40 corridor, just south of our CWA
border, where 70+ dewpoints exist, while dewpoints in our NC
counties are mostly in the lower 60s. The drier air to the north
should continue to spread south into central NC overnight. On
the contrary, easterly flow will set up as high pressure moves
off the New England coast. This could cause an increase in
clouds and possibly sprinkles or light showers in the NW NC
mountains early Monday, but leaning against that idea for now.
As of 133 PM EDT Sunday...
Keeping it dry through tonight, though some higher res models
are trying to develops showers along our southern forecast area
this afternoon into tonight along frontal boundary and lingering
higher pwats. Sprinkles/isolated showers not out of the
question mainly south of U.S. 421 from Watauga to Yadkin county.
Otherwise, expect a drier airmass into Monday though still warm.
An inverted trough/warm front tries to make it to the mountains
of NC/VA Monday. Allowed for isolated showers/storms across the
High Country into southern Wilkes, but at the same time we will
be under the upper ridge, and forecast soundings suggest capping
in place until dusk, so confidence is low on any development.
Should be close to normal for lows tonight, ranging from around
60 in the piedmont, to lower to mid 50s in the mountains, with
even some 40s in the far western valleys.
Monday temperatures still warm with highs in the 80s. Humidity
tries to creep up in the afternoon, especially south of the the
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
As of 230 PM EDT Sunday...
Upper ridge elongated from eastern Ohio Valley to the southeast will
break down through Wednesday as trough digs across the center of the
country, while remnants of Cristobal head north west of the MS River.
Moisture on the backside of the surface high with a warm front
moving north across the TN Valley and southern Appalachians
will increase this period, so after a brief respite from the
muggies, we return to humid airmass by Tuesday. Showers and
storms will be mainly confined to the southern Appalachains
Monday night, then should see an uptick in coverage Tuesday
mainly from southern WV to the NC mountain/foothills ahead of
the warm front.
We will be fully in the warm sector Tuesday night/Wednesday ahead of
the cold front and with flow turning more southwest will see better
threat of showers and storms by Wednesday afternoon at least west of
the foothills into the mountains, then the front edges east to the
piedmont Wed night, though difference in model speeds suggest
keeping at least a good chance of showers/storms around into the
evening/early overnight especially east of the mountains.
Forecast confidence is high early on, then below average for pops
Wednesday-Wed night, as far as timing.
.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 1120 AM EDT Sunday...
Broad upper trough will be situated from southern Canada south into
the TN valley. Models in general agreement that Wednesdays front
should be east of us Thursday, but upper ridge and weaker flow off
the coast may slow it down enough to keep shower chances in for at
least the piedmont.
Overall. mainly a trough along/west of us in the upper levels, into
Friday, but differences in models show up late Friday with the GFS
closing off a low over Michigan, while the ECM keeps the trough
progressive. Hence the GFS showing another front with shower threat
Friday afternoon into Saturday as the closed low sticks around over
the Ohio Valley. The ensemble mean does not show this, and is more
line with the operational Euro. As such will keep it dry Friday, but
even the shortwave per Euro Saturday may be enough to spark showers
in the heating of the day so leaned toward a slight/low chance pops.
By Sunday, both the GFS and Euro have the upper trough axis situated
over our area, with the GFS still showing the closed low over the
mid-Atlantic while the Euro is further north over southwest Quebec.
With trough axis overhead, shower chances are possible with better
chance with the frontal boundary east of our area.
Temperatures this period will be closer to normal and humidity
levels will also be tolerable most of the time, especially in the
Given the discrepancies in the models especially Friday-Saturday,
forecast confidence is average on precip chances.
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
As of 800 PM EDT Sunday...
VFR conditions are expected to prevail through much of the TAF
valid period. The exceptions will be the limited potential for
MVFR in fog at LWB early Monday and MVFR clouds morning and
again late afternoon around TNB and the far southwest part of
the CWA. Otherwise, look for mostly clear skies across the CWA
except the far southwest where developing easterly/northeasterly
flow could result in increasing MVFR clouds late tonight and
Monday, say from TNB to MJK. Otherwise, a dry air mass should
keep skies clear to partly cloudy (few to sct cu) through the
TAF valid period. Winds will be NNW west of the Blue Ridge to NE
east of the Blue Ridge overnight at speeds of 4-8 mph, becoming
NE-SE Monday morning at speeds of 5-10 mph, with low end gusts
possible mainly east of the Blue Ridge by late morning.
/Confidence Levels in Forecast Parameters/
Ceilings - Moderate to High,
Visibility - High,
Winds - Moderate to High.
/Thunderstorm Threat TAF Valid Period/
Extended Aviation Discussion...
MVFR conditions are expected to develop across the NW NC
mountains Monday evening and into far southwest VA around MJK
and toward MWK/HLX. As moist easterly flow continues and the
trail of moisture associated with the remnants of T.S. Cristobal
track through the Midwest, look for increasing amounts of MVFR
ceilings spreading north and northeast through the CWA Tue-Wed.
Scattered showers/thunderstorms return to the west/mountains
Tuesday with showers/thunderstorms likely on Wednesday as a
front moves in from the west combined with moisture from