Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/17/19
Area Forecast Discussion
National Weather Service Bismarck ND
1013 PM CDT Fri Aug 16 2019
.UPDATE...
Issued at 1013 PM CDT Fri Aug 16 2019
The thunderstorm over southern Grant County has weakened over the
past hour. However, several recently initialized CAMs assimilated
this storm and maintain it across our far south through 08Z.
Added slight chance PoPs to account for this scenario.
The cold front has entered far northwest North Dakota. Winds
behind the front are around 5 kts higher than any model indicates.
Boosted wind speeds through the middle of the night behind the
expected location of the front, tapering back towards guidance
around 09Z.
00Z high resolution guidance appears much less bullish on
widespread rain chances, which has been consistently suggested by
the last several runs of the HRRR. But given the amount of
forcing and moisture through the column per RAP soundings, think
that these CAMs may be under-producing QPF.
UPDATE Issued at 842 PM CDT Fri Aug 16 2019
Quick update to expand slight chance PoPs across western into
central North Dakota this evening. Isolated showers continue to
develop along a surface trough preceding the cold front that is
about to enter the northwest corner of the state. Some lightning
is now being observed with the strongest shower in southern Grant
County.
UPDATE Issued at 706 PM CDT Fri Aug 16 2019
A few isolated showers have developed along a pre-frontal trough
across western North Dakota. Made some adjustments to PoPs to
account for current trends. Other notable changes to the forecast
include increasing cloud cover over western North Dakota this
evening and decreasing tomorrow`s high temperatures by a few
degrees. The latter was derived from hourly NBM temperature
output.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 211 PM CDT Fri Aug 16 2019
Tonight, a cold front will swing through western and central North
Dakota. The main area of forcing for widespread precipitation
will follow behind the cold front and arrive early Saturday
morning west and mid morning central. There is good agreement
between most models that most of western and central North Dakota
will see widespread showers and isolated thunderstorms tomorrow.
SPC continues to highlight south central and the James River
Valley in a marginal risk for severe storms for Saturday
afternoon/evening. The latest model runs have the front moving
out of this area a bit slower than earlier indications, therefore,
there could be a brief window of a few hours where some isolated
severe storms could form. The main threat area would be along the
front across the far southern James Valley where there are
indications 1,000+ J/KG CAPE and 40 knots of 0-6 KM shear could
reside until the front finally moves out.
Precipitation chances end rather quickly from west to east
Saturday afternoon/evening as subsidence increases in the wake of
the embedded wave.
.LONG TERM...(Saturday night through Friday)
Issued at 211 PM CDT Fri Aug 16 2019
Quasi-zonal flow develops Sunday and remains through the week.
Occasional waves will move through the flow bringing off and on
chances for showers and thunderstorms. Temperatures should also
recover nicely back to near normal readings.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 706 PM CDT Fri Aug 16 2019
All terminals will begin this forecast period with VFR
conditions. A cold front will move across western and central ND
late tonight through Saturday afternoon. Showers and isolated
thunderstorms are expected behind the front, with winds becoming
northwesterly around 10 kts. MVFR ceilings are possible with the
showers, especially at KBIS and KDIK.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Hollan
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...Hollan
Area Forecast Discussion
National Weather Service Boston/Norton MA
958 PM EDT Fri Aug 16 2019
.SYNOPSIS...
Dry, seasonable conditions continue into Saturday, with a
chance for showers and an isolated thunderstorm north and west.
Humid, hot conditions return Sunday, continuing through midweek
when a cold front will sweep through with scattered showers and
thunderstorms. Drier and not as warm late next week.
&&
.NEAR TERM /UNTIL 6 AM SATURDAY MORNING/...
As of 955 pm...
Fairly quiet across the region. Primary weather concern
(especially for aviation and marine interests) is the developing
low clouds and fog that has been slowly moving inland and
expanding across RI & southeast MA. Had a report of 1/8mi
visibility in Nantucket Sound recently. Except for the immediate
south coast, so far it`s been low stratus and not so much fog,
but as temperatures cool and reach the dewpoint, we should see
more fog develop. Some could get a little dense, so may work up
a little statement for the overnight hours to state the obvious
that if it`s foggy, drivers need to slow down.
Otherwise made a few tweaks to the PoPs to trim back the chances
for showers out across western sections of CT and MA. Noted that
global models were showing some light precip amounts after 06z
across that region -- apparently they generate some weak
convection and/or carry convection further to our south & west
into CT/western MA later tonight. Latest HRRR and NAM3 show more
of what appears to be just a few sprinkles/light showers in
that region. Given that current radar trends seem to suggest
things will stay mostly out of the area, I trended down a bit.
Will have to keep an eye on the showers developing across
eastern PA/northwest NJ and see if they are able to maintain
themselves overnight and sneak into the forecast area prior to
dawn.
Otherwise a mostly cloudy but dry overnight, though a bit muggy
as dewpoints are well into the 60s.
&&
.SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/...
Starting off the weekend cloudy...trend will be toward gradually
mixing these clouds out, but it will be slower to happen than
today. Many may have to wait until early to mid afternoon to see
clouds becoming broken/scattered. Mostly dry once again, but the
same pattern as the last few days with the relatively zonal
flow, minor impulses passing through bringing scattered
shower/thunderstorm chances in the afternoon. Again, the best
chance for these looks to be in western MA/CT where the best
instability and mid level forcing resides. If we struggle to
clear out the clouds, that could hamper the instability as well
keeping t storm chances lower. At the moment CAPE values near
2000 J/kg and 0-6 km bulk shear could allow for a thunderstorm
or two to overcome the weak lapse rates and drier air aloft.
Overnight any showers and storms should diminish and low clouds
return on persisting SE flow. Very light surface winds and
dewpoints rising into the upper 60s keeps our low temperatures
warmer (upper 60s) and fog/stratus likely makes a return.
&&
.LONG TERM /SUNDAY THROUGH FRIDAY/...
Big Picture...
Zonal flow across the Northern tier of the USA through the weekend,
then moves north into Canada. Sub-tropical ridge extends across the
Southern USA and starts building north up the East Coast this
weekend. Multiple shortwaves move through the the zonal flow through
midweek next. Any single shortwave could trigger a couple of showers
as it moves overhead.
Contour heights (at 500 mb) build into the upper 580s and near 590
(Dm) over the weekend and early next week, then lower by Thursday.
This indicates a general warming trend through the midweek with
temperatures at or above normal. Cooler temperatures follow late
week.
Confidence is moderate-high through Tuesday. Differences arise in
the mass fields of the various models over Hudsons Bay and Central
Canada Tuesday and translate southeast across the New England by
late week. These differences in the forecast data mean a lower
forecast confidence Wednesday through Friday.
Daily Concerns...
Multiple shortwaves in the zonal flow mean multiple days that may
have scattered showers/thunder. Precipitable water values are 1.5 to
2.0 inches every day through Thursday, and stability parameters are
favorable for convection just about every day. We will forecast
chance POPs for showers/thunderstorms each day through Wednesday,
and in RI/Eastern MA Thursday.
The final shortwave moves through Thursday, moving a cold front
through the region. Expect clearing skies after that. High pressure
will be in place Friday and should provide subsidence/dry weather.
Warm very humid air moves north with the sub-tropical high.
Expect dew points in the upper 60s and lower 70s, so humidity
very-high bordering on oppressive. Lower dew points move in
behind the cold front for part of Thursday into Friday.
Mixing may be a little below 850 mb Sunday, but will be to at least
850 mb Monday through Thursday, and possibly a little higher. This
will tap 16-17C initially and 17-19C Monday to Thursday. Full mixing
in this case would support max sfc temps in the mid and upper 80s
Sunday and the upper 80s to lower 90s the first half of next week.
We used the National Blend grids for temperatures, but added a
couple of degrees for Wednesday.
&&
.AVIATION /02Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Saturday Night/...Moderate confidence.
Tonight...
VFR early in this night, except for IFR cigs along the South
Coast. After nightfall, and especially after midnight, expect
low clouds and fog to develop and expand, bringing widespread
IFR-LIFR to the coastal plain and central hills, most likely
after midnight. Where this doesn`t occur, expect spotty MVFR
conditions for low terrain terminals within valleys. E/SE winds
around 10 kts persisting.
Spot shower early tonight crossing from NY to VT via the NW
corner of MA. Most of the effect will be in Western Franklin Co
MA, far from any of the terminal forecast sites.
Saturday...
Widespread MVFR-LIFR slow to lift, becoming BKN to SCT in the
process towards low-end VFR. Lower conditions expected to linger
along the immediate shoreline. Persistent S wind around 10 kts.
Spot shower activity possible across NW MA and CT.
Saturday night...
Repeat of Friday night however could be more widespread FG issues.
High terrain terminals once again socked in. Continued S winds
and dissipating spot shower activity over NW MA and CT.
KBOS Terminal...Moderate confidence of VFR lowering to IFR-LIFR
CIGs tonight. Most likely time is after 04Z/Midnight, but low
confidence in exact timing. Conditions expected to improve
Saturday mid-late morning.
KBDL Terminal...High confidence in TAF.
Outlook /Sunday through Wednesday/...Moderate confidence.
Sunday: Mainly VFR, with areas MVFR possible. Chance SHRA,
slight chance TSRA.
Sunday Night: MVFR/IFR conditions possible. Chance SHRA, slight
chance TSRA, patchy BR.
Monday: Mainly VFR, with areas MVFR possible. Slight chance
SHRA, isolated TSRA.
Monday Night: Mainly VFR, with local IFR possible. Patchy BR.
Tuesday: Mainly VFR, with areas MVFR possible. Chance SHRA,
slight chance TSRA.
Tuesday Night: MVFR/IFR conditions possible. Chance SHRA,
slight chance TSRA, patchy BR.
Wednesday: Mainly VFR, with areas MVFR possible. Breezy. Chance
SHRA, slight chance TSRA.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Saturday Night/...High confidence.
Seas throughout at or below 4 feet as SE winds persist at around
10 kts. Will see low clouds and possible fog becoming more
widespread overnight and perhaps persisting all the way through
Saturday night as winds become S and humidity builds. Lower
confidence on precise fog conditions, especially along the near-
shore. May be a setup of low clouds with only visibility
reduced down to 6 nautical miles with mist.
Outlook /Sunday through Wednesday/...Moderate confidence.
Sunday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of rain showers, isolated thunderstorms, patchy
fog. Local visibility 1 to 3 nm.
Sunday Night: Winds less than 25 kt. Slight chance of rain
showers, isolated thunderstorms. Local visibility 1 to 3 nm.
Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
Slight chance of rain showers, isolated thunderstorms.
Monday Night: Winds less than 25 kt. Areas of seas approaching
5 ft.
Tuesday: Winds less than 25 kt. Slight chance of rain showers,
isolated thunderstorms.
Tuesday Night: Winds less than 25 kt. Chance of rain showers,
slight chance of thunderstorms.
Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain showers, slight chance of thunderstorms.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.
&&
$$
SYNOPSIS...WTB/BW
NEAR TERM...Nash
SHORT TERM...BW
LONG TERM...WTB
AVIATION...WTB/BW
MARINE...WTB/BW
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
705 PM CDT Fri Aug 16 2019
.AVIATION...
/00Z TAFS/
VFR conditions are expected for area sites through the overnight
hours. MVFR cigs are forecast for KSAT and KSSF to begin at 10Z and
last to 14Z Saturday as low level clouds develop and linger around
through that time. Kept KAUS with VFR SCT015 cigs from 10Z through
14Z as suggested by latest forecast soundings. Otherwise, VFR cigs
return and prevail across the area after 14Z Sat. with winds out of
the southeast and south at 6 to 12 knots with occasionally gusts up
to 18 knots.
&&
.PREV DISCUSSION... /ISSUED 244 PM CDT Fri Aug 16 2019/
SHORT TERM (Tonight through Saturday Night)...
Convective temperatures have been reached and vertical CU depth is
increasing across portions of the Hill Country per latest GOES-East
visible imagery. Isolated showers recently developed across Burnet
and Kerr counties. Additional development of isolated showers and
potentially isolated thunderstorms is expected through the remainder
of the afternoon across portions of South Central Texas, per latest
runs of the HRRR and 12Z HREF. Given the weak deep layer shear,
individual showers and storms shouldn`t last long, as they build
and collapse quickly. However, can`t rule out isolated stronger
downdrafts producing gusty winds, similar to last few afternoons, if
anything deeper develops. This isolated activity should end after
sunset.
The upper level ridge is forecast to expand slightly over the region
through the weekend, and rain chances look too low to mention on
Saturday. Heat index values this afternoon are generally in the
103-107 degrees range, however some locations east of I-35 and I-37
have reached 108-109 degrees. There should be an increase in areal
coverage of locations that reach 108 degrees Saturday afternoon, and
a Heat Advisory could be required.
LONG TERM (Sunday through Friday)...
The heat looks to peak over the weekend and into Monday. Beyond
Monday the center of the upper level ridge looks to shift northwest
of the region and could open up a slight chance for showers across
the Coastal Plains each afternoon Tuesday through Thursday. A slight
slight reduction in the heat is expected over South Central Texas
beyond Monday as well, but still warm.
A tropical wave is expected to move into the west and northwest Gulf
of Mexico Thursday and Friday. 12Z GFS and ECMWF runs have trended
towards keeping the deeper pool of tropical moisture east of South
Central Texas Friday through next weekend, however caution should be
exercised this far out when viewing individual model runs with a
large ensemble spread.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 78 103 79 103 79 / 0 0 0 0 0
Austin Bergstrom Intl Airport 78 100 78 101 77 / 0 0 0 0 0
New Braunfels Muni Airport 76 101 77 102 77 / 0 0 0 0 0
Burnet Muni Airport 76 99 76 100 76 / 0 0 0 0 0
Del Rio Intl Airport 80 106 80 105 79 / 0 0 0 0 0
Georgetown Muni Airport 78 101 78 101 77 / 0 0 0 0 0
Hondo Muni Airport 76 104 76 104 77 / 0 0 0 0 0
San Marcos Muni Airport 77 101 77 101 77 / 0 0 0 0 0
La Grange - Fayette Regional 78 101 79 101 78 / 0 0 0 0 0
San Antonio Intl Airport 78 101 78 101 79 / 0 0 0 0 0
Stinson Muni Airport 78 103 79 104 79 / 0 0 0 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Aviation...17
Short-Term/Long-Term...Huffman
Public Service/Data Collection...EWilliams
Area Forecast Discussion
National Weather Service Hastings NE
933 PM CDT Fri Aug 16 2019
.UPDATE...
Issued at 932 PM CDT Fri Aug 16 2019
Forecast has been updated to include potential for some fog
development overnight primarily across the northwest third of our
cwa per latest HRRR and SREF probs.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 308 PM CDT Fri Aug 16 2019
An upper level wave dropping southeast out of Wyoming will help
spark some late night convection across the local area. Models
have been keying in on this being a late night event focused
primarily south of interstate 80...with the latest NAMnest trying
to develop a line of thunderstorms near the state line just before
midnight and tracking them east overnight...where the low level
jet should help flare up the convection further as it exits the
local area during the very early morning hours Saturday.
While the focus of thunderstorm activity should be across our
Kansas counties late tonight...do see a small potential for at
least a few thunderstorms across the entire forecast area...so
have some isolated thunderstorms chances mentioned for everyone.
That said...the severe focus should remain south of interstate
80...where good shear will combine with modest instability and the
best forcing for at least the potential of quarter sized hail and
60 mph wind gusts. There then should be a notable break in
thunderstorm chances during the daytime hours Saturday with partly
sunny skies and warmer temperatures there will be some adiabatic
compression ahead of the next front which will bring another
chance for severe weather to the local area Saturday night.
.LONG TERM...(Saturday night through Friday)
Issued at 308 PM CDT Fri Aug 16 2019
Expect a cold front to cross northern Nebraska Saturday
night...providing the forcing for showers and thunderstorms across
much of the local area late Saturday night into Sunday morning.
With fairly good forcing from this frontal boundary, 3000+ joules
of CAPE to work with along with modest shear...see the potential
for any storms that do develop to become severe...and
not surprisingly much of the local area is currently advertised
in a slight risk for severe weather tomorrow night. While model
coverage of thunderstorm activity is not extremely high, felt it
was prudent to expanded thunderstorm coverage given the set-up
that will be in place across the local area. As this front then
washes out across the local area Sunday...expect cooler
temperatures along with a transition in the upper level
flow...which will result in a ridge building back over the plains
to start the new work week. What this means is that temperatures
should climb back above normal to start the work week...and with
a sticky airmass in place...expect to see heat index values climb
into the 100 to 110 degree range across much of the local area
especially Monday afternoon...but possibly Tuesday afternoon as
well.
The good news here...however...is that the upper level ridge
responsible for the spike in apparent temperatures and dry weather
both Monday and Tuesday will retreat some by mid-week. This will
allow for a more northwesterly upper level pattern to return
bringing various small thunderstorm chances...along with slightly
cooler...yet seasonable temperatures...to finish out the work
week.
&&
.AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Saturday)
Issued at 554 PM CDT Fri Aug 16 2019
The TAF period will start off with light winds and mainly clear
skies. Storms along the high plains are expected to roll eastward
overnight and could impact the terminals around 06Z or shortly
thereafter, however some models suggest convection may focus
farther south of KEAR and KGRI and will need to monitor trends.
While VFR conditions are forecast for the most part, some models
suggest the potential for a few hour period with MVFR cigs and
possibly reduced visibility in fog toward day break Saturday. Any
fog/low clouds will erode Saturday morning with VFR conditions
returning.
&&
.GID WATCHES/WARNINGS/ADVISORIES...
NE...None.
KS...None.
&&
$$
UPDATE...Fay
SHORT TERM...Rossi
LONG TERM...Rossi
AVIATION...Fay
Area Forecast Discussion
National Weather Service Grand Rapids MI
758 PM EDT Fri Aug 16 2019
LATEST UPDATE...
Mesoscale Discussion/Aviation
.MESOSCALE DISCUSSION...
Issued at 759 PM EDT Fri Aug 16 2019
Instability is gradually pushing into the area from the SW, ahead
of the incoming wave from the west. SPC mesoanalysis page
indicates that the far SW corner of the area toward South Haven
has likely reached 1,000-1,500 J/kg of MU CAPE. This instability
is more related to the wave and moisture coming in, instead of
diurnal instability.
The models indicate that this MU CAPE axis will push east ahead of
the wave. A 25 knot low level jet is likely feeding this
instability. This will continue to provide fuel for the expected
storms. Effective shear is decent around the area with values up
to 40 knots. The storms will be mostly elevated in nature, but
can not rule out a wind gust punching through, or some small hail.
&&
.SYNOPSIS...
Issued at 145 PM EDT Fri Aug 16 2019
- Thunderstorms this evening
- Thunderstorms Sunday morning, stronger storms Sunday afternoon
- Warm and humid this weekend with increasing waves at Lake Michigan
- Next chance for storms Tuesday
&&
.DISCUSSION...(This evening through next Friday)
Issued at 308 PM EDT Fri Aug 16 2019
Most forecast concerns center on this weekend, which for many, will
be the last days of summer. Warm and sunny conditions are expected,
many people will likely be outside and on the beaches, and there
will consequently be greater exposure to any hazardous weather that
occurs.
--Thunderstorms this evening--
The latest SPC outlook and recent runs of the HRRR show a greater
likelihood for strong thunderstorms this evening crossing Lake
Michigan. Another focus area is mainly south of I-96 and
particularly near I-94. The stronger storms will feature frequent
lightning, brief heavy rain, and possible small hail. There is
less certainty regarding the wind threat.
Forecast reasoning: an impressive upper PV max well depicted on
channel 8 W/V imagery is currently moving east into IA. Low level
southwesterly flow/theta-e advection/destabilization should increase
this afternoon with the indirect circulation ahead of this PV max.
This will likely coincide with when the boundary layer decouples and
a diurnally forced Low-Level Jet (LLJ) commences over southern Lower
Michigan in response to the inertial adjustment. However, the
decoupling process and associated LLJ response are difficult to
anticipate exactly. Therefore, it is possible for storms over
southern Lower Michigan to be elevated...or not...which will dictate
the wind threat and overall storm intensity given how low level
theta-e/advection/ destabilization processes are allowed to
proceed.
Meanwhile, regarding the newly identified convective threat area, we
see thunderstorms developing over central Wisconsin along a cold
front and these will likely continue to intensify with diurnal
heating and the aforementioned processes with the approaching PV
max. Given that forcing with the cold front should be more surface
based, these storms have better potential for strong to severe wind
gusts. Thunderstorms across our forecast area in general could
last more than just a few hours if the LLJ manages to interact
favorably with the approaching cold front and/or any convectively
generated cold pool. Locally heavy rain is not out of the
question, but fortunately, our local soundings are comparatively
dry which should help mitigate the threat.
-- Thunderstorms Sunday--
It looks increasingly likely we`ll have a wave of thunderstorms
Sunday morning followed by second round in the afternoon. This
second round of thunderstorms could be severe and would not be
surprised to see the SPC outlook risk upgraded from marginal to
slight.
Forecast reasoning: A morning round of thunderstorms often will
temper or eliminate afternoon convection, and we`ve seen a lot of
that lately. Although this is possible again Sunday, it`s less
likely for a couple reasons. First, we are seeing a consistent
signal for a seasonably strong cold front to displace a warm humid
airmass around peak heating. That alone is hard to escape unscathed.
However, this is also accompanied by a deep, anticyclonically
breaking upper wave crossing our area with anomalously strong zonal
flow in the lower troposphere, particularly below 700 mb. This
pattern favors a stout low level jet during the day, as indicated by
many of the deterministic runs, meaning that we could see
significant daytime destabilization between these two rounds of
storms. Storm organization should be enhanced by effective shear
that is expected to exceed 30 knots.
- Warm/humid this weekend with increasing waves at Lake Michigan --
We expect heat indices to be higher on Sunday with increased
humidity, although maximum values should stay around 90F. Please see
Marine section for details regarding waves.
-- Next chance for storms Tuesday --
No change to previous thinking regarding Tuesday or the latter half
of the coming week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 759 PM EDT Fri Aug 16 2019
Two main points of interest for this set of forecasts. The first
will be the threat of convection through about 06-08z. The second
is fog/low cloud potential late tonight toward daybreak.
We anticipate a sct-bkn line of showers and storms to start
impacting the western terminals by about 02z, and then spreading
east. We believe there is a good enough chance the storms will
impact the terminals to mention a tempo group. Showers and storms
should then clear the eastern terminals toward 07z or so.
If the sites get rain tonight, there is some potential for fog.
The fog threat will be limited due to some wind remaining up. This
would support a better chance of lower stratus possibly
developing. We believe skies should be fairly clear aside from
any stratus in the morning. A cumulus field is likely to form,
especially down south where there should be more moisture.
&&
.MARINE...
Issued at 308 PM EDT Fri Aug 16 2019
Webcams currently show low waves nearly everywhere. However, the
Ludington buoy is up to nearly 3 feet. Waves there will likely
increase a bit more in the next couple hours prior to winds
weakening and turning southwest ahead of a cold front approaching
from Wisconsin.
After this, we are concerned about wind and waves Sunday. South
winds will be stronger than today, raising the concern of longshore
currents and waves topping piers given the high water levels. As
mentioned before, this will be the last day of summer for many and
we expect a heavy turnout at the beaches regardless of morning
thunderstorms. This will continue to be one of our greater hazard
concerns this weekend.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...None.
LM...None.
&&
$$
MESOSCALE...NJJ
SYNOPSIS...TJT
DISCUSSION...TJT
AVIATION...NJJ
MARINE...TJT
Area Forecast Discussion
National Weather Service Wilmington NC
1025 PM EDT Fri Aug 16 2019
.SYNOPSIS...
Unsettled weather will last into the weekend as a stalled front
weakens along the coast. A slight drying trend on Monday will
give way to an active weather pattern with scattered showers and
thunderstorms each day next week while temperatures remain near
normal.
&&
.UPDATE...
I continue to favor the HRRR with convective trends along the
coast late tonight into Saturday. PoPs/Wx/QPF tweaked
accordingly.
&&
.NEAR TERM /THROUGH SATURDAY/...
Main concern for the next 36 hours is the development of
thunderstorms with potentially heavy rain at times.
Stationary front positioned over the Carolinas is expected to change
very little today into Saturday with plenty of atmospheric moisture
present, leading to humid conditions with chances for showers and
thunderstorms mainly east of I-95, with coastal areas along the
highway 17 corridor having an increased chance for precipitation.
Although models have some spatial differences, there is fairly good
agreement and confidence is high for showers and thunderstorms to
produce heavy rain at times with the potential for minor flooding,
especially for low lying or poor drainage locations, if storms
continue to pass over the same areas.
Cloud cover along the stationary boundary will lead to a lack of
sunshine at times with cooler weather. Patchy fog is possible with
abundant moisture and high relative humidities overnight tonight and
into Saturday morning. Afternoon highs through Saturday afternoon
will be near to slightly below average for this time of year in the
mid to upper 80s and just above 90 in some locations.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/...
As of 300 PM Friday...Unsettled weather will continue through the
period though likely with the intensity of the near term. Low
pressure passing by off the coast Saturday night will draw deep
layer frontal moisture closer to the coast. Some guidance is
suggesting that this will be adequate enough to decrease rain chances
and amounts substantially, but have opted at this time to stay close
to previous forecast in showing scattered coverage.
&&
.LONG TERM /MONDAY THROUGH FRIDAY/...
As of 300 AM Friday...Mid level flow remains quite weak through the
period while at the surface and low levels winds will remain
southwesterly. This will advect enough moisture into the area for at
least scattered showers and thunderstorms each day. The nocturnal
hours will offer lower rain chances with the loss of instability but
guidance shows that shallower convection will remain possible.
Daytime highs and nighttime lows will stray little from seasonable
norms.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Cold front continues to sit over our inland areas with tropical
moisture streaming in from the southwest, This will make
aviation forecasts challenging along the Carolina coast on
Saturday. Expect widespread shower activity to wane slightly
over the next few hours as a outflow boundary moves southward
across the area, igniting widespread thunderstorms along its
front edge. Once this moves offshore, there will be a break in
the precip before the marine BL produces overnight TS. Inland
terminals will likely stay dry until tomorrow afternoon as
storms fire along the stalled front, but MVFR/IFR stratus is
likely on Saturday morning, especially if the front passes these
terminals. Periodic MVFR/IFR from passing thunderstorms is
likely on the warm side of the front. There doesn`t seem to be
an organized line or shield of precipitation to help with
forecasting the timing of the flight restrictions. In general,
expect mostly VFR with MVFR in rain showers, IFR in the
strongest cells.
Extended...An active summer period with increased moisture and the
threat for MVFR/IFR conditions from afternoon and evening
thunderstorms each day. Morning low stratus and fog will produce
MVFR/IFR conditions this weekend into next week.
&&
.MARINE...
Waves out of the south at significant heights of 3 to 5 feet at 6
seconds through tonight decreasing to 2 to 4 feet Saturday. Light
swell from the southeast between 6 and 8 seconds. Southwest winds
for the next 36 hours from the southwest between 5 and 15 mph with
gusts approaching 25 kts at times, especially during the afternoon.
Showers and thunderstorms likely as a stationary front inland allows
for unstable weather. Waves and winds could be locally higher in
thunderstorms.
As of 300 PM Friday...Southwesterly winds in the 10-15kt range
Saturday night will settle to 10kt later in the period as
Atlantic high pressure extends a ridge axis into the Carolinas.
For the same reason, early period seas of 3-4ft will settle to
2-3ft late in the period.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...MBB
UPDATE...TRA
NEAR TERM...MCK
SHORT TERM...MBB
LONG TERM...MBB
AVIATION...21
Area Forecast Discussion
National Weather Service Indianapolis IN
1110 PM EDT Fri Aug 16 2019
.UPDATE...
The Aviation section has been updated below.
&&
.SYNOPSIS...
Issued at 359 PM EDT Fri Aug 16 2019
A warm front will lift north through the area on Saturday...bringing
hotter and more humid air back into central Indiana for this weekend
into the middle of next week. Daily threats for a few showers and
thunderstorms are expected as well. Cooler weather will return by
late next week.
&&
.NEAR TERM /Tonight/...
Issued at 359 PM EDT Fri Aug 16 2019
An abundance of mid and high level cloud cover drifting across the
region this afternoon. Have seen a few small light showers or
sprinkles tracking east but in the absence of substantial forcing
and instability...have not been able to generate any convection.
With the greater cloud coverage...temps have been kept down a bit
with 19Z readings generally in the upper 70s and lower 80s.
Low confidence forecast as model guidance once again providing
varying solutions with respect to how convection is likely to evolve
this evening into the overnight along a warm front surging into the
mid Mississippi Valley. To this point...storms have been focused in
southwest Missouri and southeast Kansas in close proximity to the
boundary lifting north and along the theta-e ridge. CAMs appear to
have captured this much better than some of the other models which
are trying to generate convection further north across Missouri into
western Illinois by early this evening. Have some significant doubts
in that solution coming to fruition considering instability is
weaker in those areas and the NAM in particular appears to be
shifting the front north more quickly than what is actually
occurring.
The HRRR and WRF runs do both develop a convective cluster along the
front over northern Missouri but do so about 4 to 6 hours later late
evening into the overnight. Prefer this solution with a later
arrival from the west of showers and storms as the warm front
approaches. Low level forcing develops into the region at the nose
of an increasing jet during the predawn hours...with the greatest
chance for remnant showers and storms from the cluster that develops
to the west to impact portions of the area towards daybreak
Saturday. Will primarily focus pops after the 06-09Z time period as
a result. Not particularly impressed with the potential for more
robust storms late tonight as instability remains marginal and
elevated.
Temps...low level moisture is slowly but steadily advecting into the
region and will continue to do so overnight as the warm front
approaches. Low level thermals generally support lows in the upper
60s which is in line with guidance.
&&
.SHORT TERM /Saturday through Monday/...
Issued at 359 PM EDT Fri Aug 16 2019
Forecast challenges focus on a return to a hotter and more humid
airmass along with continued threats for convection to impact parts
of the forecast area as the warm front lifts north through the area
this weekend.
Dirty upper flow pattern will remain across the Ohio Valley and
lower Great Lakes with ripples of energy traversing through a
progressive quasi-zonal pattern. Heights aloft will rise into early
next week with subtle ridging developing by Monday...shifting the
waves aloft north into the Great Lakes.
Convection is likely to be ongoing across the forecast area Saturday
morning as the cluster that develops late tonight to our west tracks
into the region before weakening and/or diminishing by late morning.
With the warm front over the region Saturday afternoon and
evening...likely to be additional convective development as an
increasingly moist and unstable airmass expands into the region.
Focus for showers and storms will gradually shift north across the
forecast area into Saturday night as the warm front lifts north.
With the boundary north of the region for Sunday and Monday and
little forcing aloft present...hard to justify more than low chance
pops for isolated...diurnally driven storms. While any of these
storms may throw out strong wind gusts as cores aloft collapse...
expect lightning and brief heavy rainfall to be the primary impacts.
The growing story will be the heat and humidity as an oppressive
airmass settles into central Indiana. Peak heat indices will surge
into the mid and upper 90s for Sunday and Monday afternoons.
Temps...leaned at or above guidance for highs through the period
which is supported by low level thermals. After a relatively
pleasant day in the 80s Friday...highs will rise into the lower 90s
for Sunday and Monday. Used a model blend for lows recovering into
the upper 60s and lower 70s.
&&
.LONG TERM /Monday Night through Friday/...
Issued at 256 PM EDT Fri Aug 16 2019
A potentially unsettled beginning half of the extended timeframe
is expected. With elevated heat and humidity across central
Indiana, a series of weak upper level disturbances will push
across the forecast area from the beginning of the period through
Tuesday night...keeping rain chances in the forecast. Above normal
temperatures are expected for Tuesday and Wednesday.
A stronger upper low digs southeast over the Great Lakes on
Wednesday...sending a cold front through the area. This front
looks to bring some relief from the heat...allowing maximum temps
on Thursday and Friday to only rise to the upper 70s to lower 80s
across the forecast area. Dry conditions are also expected after
the frontal passage.
&&
.AVIATION /Discussion for the 17/06Z TAFs/...
Issued at 1110 PM EDT Fri Aug 16 2019
VFR throughout the period at most sites. LAF may have a period of
MVFR Saturday morning in showers and storms. Other sites may have
brief forays into MVFR in precip but too uncertain to include now.
Winds will generally remain west/southwesterly through the period
at 10KT or less.
A few showers may pass near LAF early in the period, and showers and
a few storms may overspread the other sites Saturday morning, but at
this point, these chances have become a bit more uncertain. Will
keep a mention out for now.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SYNOPSIS...Ryan
NEAR TERM...Ryan
SHORT TERM...Ryan
LONG TERM...MRD
AVIATION...Nield
Area Forecast Discussion
National Weather Service Pueblo CO
909 PM MDT Fri Aug 16 2019
.UPDATE...
Issued at 909 PM MDT Fri Aug 16 2019
Updated grid and zone forecasts to cancel Severe Thunderstorm
Watch for Kiowa county and also to refresh meteorological grids.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 222 PM MDT Fri Aug 16 2019
Slightly more convection than yesterday developing over the
higher terrain this afternoon as upper forcing is stronger with
wave moving by to the north. However, sparse low level moisture
over the mountains, valleys and I-25 corridor will produce mainly
high based/windy storms, with only light precipitation. Deep
instability lies along and east of a line from just east of
Colorado Springs to east of Pueblo to near Clayton NM as of 21z,
with CAPE in the 1000-3000 J/KG range as dewpoints have held in
the lower 60s near the KS border. As better forcing moves over
this area late this afternoon into this evening, expect at least
sct strong/severe storms to develop, with HRRR depiction of rather
isolated but intense convection across Kiowa/Bent/Prowers
counties looking reasonable. SWOMCD already out for this area,
with severe watch from Kiowa county northward just issued.
Storms then shift east into KS by midnight, with convective
outflow potentially pushing some lower clouds and fog back into
the ern plains by early Sat morning. On Sat, low level moisture
mixes out all the way to the KS border in the afternoon, leaving
just a very low risk of a weak storm near the Palmer Divide by
late in the day. Max temps look to creep upward a degf or two as
air mass dries out.
.LONG TERM...(Saturday night through Friday)
Issued at 222 PM MDT Fri Aug 16 2019
Sunday and Monday look dry/hot as upper ridge builds slowly
over the southern Rockies. Models suggest air mass will by dry
enough to preclude convection over the entire area Sunday, with
only some very isolated/weak storms back toward the San Juans on
Mon. Much of the area should see their hottest temps of the next
several days on Mon, and most of the southeast plains east of
I-25 will reach the 100f mark. Moisture begins to return to the
region on Tue, with weak frontal boundary on the plains Tue
evening aiding in thunderstorm formation as well. Wed may end up
being the wettest day with weak upslope and mid-level moisture in
place, then rain chances gradually decrease toward the end of the
week as mid level flow takes on a more wly component. Temps will
remain rather hot on Tue, before sinking back toward seasonal
averages from Wed onward.
&&
.AVIATION...(For the 00Z TAFS through 00Z Saturday evening)
Issued at 222 PM MDT Fri Aug 16 2019
Isolated tsra possible at all taf sites through 00z-02z, though
with air mass drying, expect main impact of storms at all
terminals to be gusty/erratic winds of 35-45 kts. Risk of
strong/severe storms with large hail will be farther east on the
plains, close to the KS border. Storms end overnight, with
easterly winds bringing patchy low clouds and fog to areas east of
I-25 early Sat morning. On Sat, VFR all terminals, with only a
minimal chance of a tsra over the higher terrain north and west of
KCOS.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
Area Forecast Discussion
National Weather Service Blacksburg VA
745 PM EDT Fri Aug 16 2019
.SYNOPSIS...
High pressure will cover the central and southern Appalachians
into the Saturday, but isolated to scattered afternoon and
evening thunderstorms are possible each day. Precipitation
chances increase early next week as a frontal boundary enters,
and then stalls over the area.
&&
.NEAR TERM /THROUGH SATURDAY/...
As of 745 PM EDT Friday...Moisture boundary on east-northeast
winds, separating surge of 70+ degree dewpoints east of it to
mixed dewpoint air on west winds across the I-77 corridor into
southeast WV has sparked a few heavier showers near the
Blacksburg/Christiansburg area. These could produce a quick
heavy downpour and a rumble or two of thunder as they sag
southward. An isolated thunderstorm was also shown per composite
radar mosaic imagery moving into western Buckingham County from
southern Nelson County. Recent runs of the HRRR and the 18z
NAM-3km seem to insist on developing additional convection along
the southern Blue Ridge south of Roanoke and shifting it south-
southeastward into the NC foothills and northwest Piedmont of
NC between 00-03z. One or two could reach strong levels with
heavy downpours and brief gusty winds but severe weather isn`t
expected, especially given how late in the day things have
started to pop.
Beyond sunset, forecast challenges then turn to fog coverage and
on potential stratus development in the VA/NC Piedmont. Fog
should again re-develop in the deeper western mountain valleys.
After midnight, while 925-850 mb southeasterlies weaken, several
model sky cover forecasts in this timeframe including the NAM
and the HREF show a large area of low-cloud cover that sets in
and makes it at least as far west as Highway 29. May be more of
an aviation impact, but possibility that lows could be too cool
if cloud cover is thick enough.
Prior discussion from 400 PM follows...
Similar to Thursday best coverage of thunderstorms will be along
and east of the Blue Ridge through the evening. Best CAPES will
be in the North Carolina and Virginia piedmont outside of where
the low clouds were this morning. Thunderstorms will diminish
by late evening.
Expecting fog again in the favored western valleys and over area
rivers and lakes again tonight. Any locations that get rain this
afternoon will have a higher probability of fog tonight.
Thunderstorms will develop again Saturday afternoon but coverage
will be scattered to isolated and again mainly along and east of
the Blue Ridge.
Stayed closed to bias corrected guidance for lows tonight and
highs on Saturday.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
As of 230 PM EDT Friday...
High pressure will head away from the Mid Atlantic during Saturday
night, which will allow a shortwave upper level trough to cross over
the Great Lakes on Sunday. This trough should pass well to our north
during Sunday night. In addition, the latest model runs have picked
up on a weak upper level low developing along the South Carolina
coast. Its energy and vorticity should feel the influence of the
passing shortwave trough to the north. Consequently, the models show
the weak upper level low drifting northward over eastern North
Carolina by Sunday night and over eastern Virginia by Monday and
Monday night.
The above synoptic pattern will be combined with a hot and humid air
mass due to good surface heating and decent moisture flow from the
Gulf and the Atlantic. Moisture convergence combined with
orographical lift should be enough to allow isolated showers and
thunderstorms to pop up in the mountains during Sunday afternoon.
Higher confidence for convection to fire exists on Monday afternoon
as the weak upper level low draws closer to aid in synoptic lift.
Wind shear will be too weak during both days to allow much
convective organization, so expect the storms to be pulsy in nature.
&&
.LONG TERM /TUESDAY THROUGH FRIDAY/...
As of 300 PM EDT Friday...
A weak upper level low will drift over the southern Chesapeake Bay
on Tuesday and depart toward Cape Cod by Wednesday. Meanwhile, a
more vigorous upper level trough will dig southeastward from Canada
to push a potent cold front from the northern Plains toward the Ohio
River Valley. With no discernible changes expected in the air mass,
hot and humid conditions will continue with a daily threat of
scattered afternoon showers and thunderstorms.
Confidence is increasing for more widespread convection during
Wednesday afternoon through Thursday as the cold front approaches.
This front will reach the Appalachian Mountains by Wednesday night
and cross over the Mid Atlantic during Thursday. By Friday, the
models disagree on how far south this cold front will track before
possibly stalling over North Carolina. The ECMWF shows a more potent
surface high behind the cold front than the GFS and is thus more
progressive with drier air arriving from the north.
&&
.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
As of 745 PM EDT Friday...
Heavier showers have just recently developed near Blacksburg,
and it`s this terminal thas has the best chance of seeing
sub-VFR restricted conditions from showers or thunderstorms
through 02z. Best chance for additional SHRA/TSRA development
would be along the southern Blue Ridge south of Roanoke on into
the foothills. After midnight (between 07-08z thru 13z), likely
to see fog re- develop at Lewisburg and Blacksburg TAFs and
along remaining sections of the NRV into the southern Shenandoah
Valley. Guidance also suggests low stratus could advect
westward after 09z to potentially affect Lynchburg and Danville
with MVFR type ceilings, but confidence on coverage of ceilings
is pretty low.
Any fog and stratus that does set in should burn off before 15z.
Most areas should be dry on Saturday, though isolated garden
variety thunderstorms could develop along and east of Highway
29 - the Lynchburg and Danville TAFs mainly. East of the Blue
Ridge, look for southeast winds under 5 kts, with south to
southwest winds west of the Ridge at similar speeds.
.Extended Aviation Discussion...
Moisture increases Sunday into Tuesday with a surface boundary
becoming parked across the region. Look for increasing chance of
showers/storms during this time period with more opportunities
for sub-VFR conditions in addition to the overnight/morning fog.
Confidence in this part of the aviation forecast is moderate.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...AMS/PM
NEAR TERM...AL/AMS
SHORT TERM...PW
LONG TERM...PW
AVIATION...AL/AMS
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
847 PM EDT Fri Aug 16 2019
.UPDATE...
Convection is winding down with some areas of light rain
continuing for the next few hours. Later tonight expect to see
showers and a few thunderstorms redevelop over the eastern Gulf
waters and move onshore, especially along the Nature Coast where
more heavy rainfall is possible. Over the weekend the pattern
change will get underway, but for Saturday and Saturday night the
band of deepest moisture and highest rain chances will remain
across the Nature Coast. On Sunday the northern Nature Coast will
hold on to the deep moisture while elsewhere some drier air will
move in leading to lower rain chances and some more sunshine.
Overall the forecast looks ok with no major changes for evening
update.
&&
.AVIATION...
Some MVFR/local IFR conditions could affect TPA, PIE, SRQ, and
LAL later tonight into Saturday morning as convection redevelops.
Further south the majority of the convection should remain
offshore and not expected to affect PGD, FMY, and RSW until late
morning and afternoon Saturday. Southwest to south winds at 5 to
10 knots will continue overnight into Saturday morning then become
more southwest to west at around 10 knots late Saturday morning
and afternoon.
&&
.MARINE...
High pressure ridging south of Florida will continue to generate
breezy southwesterly winds across the waters tonight with exercise
caution criteria over the northern and central waters. The ridge
will lift north into the waters by Sunday into early next week,
with winds gradually turning to southerly and southeasterly. After
tonight, winds are generally expected to remain below headline
criteria outside of any showers and thunderstorms.
&&
.Prev Discussion... /issued 239 PM EDT Fri Aug 16 2019/
SHORT TERM (Today - Saturday)...
The upper ridge remains suppressed over southern Florida allowing
for troughing over the eastern half of the U.S. to remain the
dominant feature over the next couple of days. A southwest flow will
continue allowing for the rainfall and thunderstorm producing
machine to keep pumping continued showers and storms in from the
gulf coast waters keeping the region very wet. This has warranted
the extension of the Flood Watch for west central and southwest
Florida through Saturday morning. The 12Z morning sounding is
showing a slight decrease in moisture, but still coming in at 2.04
inches PWAT and southwest winds through 20k feet. Moisture will
remain high based on forecasted soundings coming in around 2 inches
PWAT before a slight drying out beginning on Sunday dropping below 2
inches for the first time in a couple of weeks. Latest HRRR guidance
keeps rain chances high with a 50-80% POPs expected across the
region today and tomorrow. With the extensive cloudiness and high
rain chances, daytime high temps will run below average for the next
couple of days.
LONG TERM (Saturday Night - Friday)...
A generally zonal flow pattern is expected in the upper-levels of
the atmosphere through mid- week. This will allow the surface
subtropical high to build back in across the peninsula. With
surface high pressure driving winds anticyclonically (clockwise)
around the high, WSW flow will finally come to an end and easterly
flow will return to the peninsula. Through mid-week, a return to
a more typical summertime pattern is expected. Scattered afternoon
and evening thunderstorms are expected, with highs in the upper
80s near the coast and lower 90s inland.
By late next week, a meridional pattern will return, as a
significant positively tilted trough axis begins to swing south
across the Central CONUS. While the bulk of this system will remain
well to the north, the GFS, ECMWF, and Canadian are suggesting the
trough could dig far enough south to bring WSW flow back into the
equation Thursday into Friday. This would mean that wet conditions
may return by the end of next week.
FIRE WEATHER...
Scattered to numerous showers and storms each day combined with high
humidities will preclude any fire weather concerns through the
period.
&&
.Preliminary Point Temps/PoPs...
TPA 76 89 76 90 / 80 70 30 50
FMY 76 90 75 92 / 40 40 20 50
GIF 75 89 74 92 / 50 50 20 70
SRQ 76 90 75 91 / 60 50 20 50
BKV 74 87 74 91 / 90 70 30 60
SPG 76 89 76 90 / 70 70 30 50
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...High Rip Current Risk through Saturday morning for Coastal
Charlotte-Coastal Hillsborough-Coastal Lee-Coastal Manatee-
Coastal Sarasota-Pinellas.
Flood Watch through Saturday morning for Coastal Charlotte-
Coastal Citrus-Coastal Hernando-Coastal Hillsborough-
Coastal Lee-Coastal Levy-Coastal Manatee-Coastal Pasco-
Coastal Sarasota-DeSoto-Hardee-Highlands-Inland Charlotte-
Inland Citrus-Inland Hernando-Inland Hillsborough-Inland
Lee-Inland Levy-Inland Manatee-Inland Pasco-Inland Sarasota-
Pinellas-Polk-Sumter.
Coastal Flood Advisory until 8 PM EDT Saturday for Coastal Levy.
Gulf waters...None.
&&
$$
UPDATE/AVIATION/MARINE...Close
PREV DISCUSSION...Wynn
UPPER AIR...Norman
DECISION SUPPORT...Oglesby