Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/19/19
Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
929 PM CDT Thu Jul 18 2019
.UPDATE...
Issued at 928 PM CDT Thu Jul 18 2019
Precipitation looking unlikely for the rest of the evening, so
have removed POPs. No changes made to winds or temperatures at
this time.
&&
.SHORT TERM...(This Evening through Friday Night)
Issued at 251 PM CDT Thu Jul 18 2019
An area of low pressure is situated over south central SD this
afternoon. The airmass associated with the surface low is unstable
with 3-4K J/kg of MLCAPE. Deep layer shear of 40 knots indicates
the environment is conducive for convection through this evening.
With little to no upper level support, or very weak forcing,
storms will probably have a difficult time developing. Increasing
700 mb temps will also limit the convective potential. The past
few runs of the HRRR keeps most of this CWA dry through tonight.
There is a small indication for a storm or two to develop over
north central SD yet this afternoon. This storm would track
southeast into a more unstable environment with hail and winds
possible.
On Friday, a weak upper level shortwave will cross across the
region, with most of the thunderstorm active in North Dakota. Can
not rule out a few storms along the ND/SD during the morning hours
on Friday. If the NAM is correct, accas showers will be possible
east of I29 Friday morning. Left this area dry for now. A stronger
upper level shortwave will push through the region Friday night. At
this time, most of the precipitation should occur post frontal with
limited threat for severe storms.
.LONG TERM...(Saturday through Thursday)
Issued at 251 PM CDT Thu Jul 18 2019
Northwest flow aloft this weekend will help keep temperatures on the
cool side for mid/late July, with highs in the upper 70s to low 80s.
The muggy air will be shunned further south along with the hotter
air as well; relatively dry mid to upper 50 dewpoints are expected.
A dominant ridge of high pressure builds across the High Plains to
start the work-week, and it remains in control through much of the
remainder of the long term. Apart from some lingering shower/storm
activity Saturday morning from an exiting frontal boundary, as a
result, our area will be largely dry through the period. The main
upper-level energy should slide well north of the area, into Canada.
Temperatures will gradually recover during the work-week as well,
from near normal through the first half to above average by the
second.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday Evening)
Issued at 622 PM CDT Thu Jul 18 2019
VFR conditions will prevail across the area tonight and through
the day Friday.
&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&
$$
UPDATE...Parkin
SHORT TERM...SD
LONG TERM...Lueck
AVIATION...Parkin
Area Forecast Discussion
National Weather Service Gaylord MI
1143 PM EDT Thu Jul 18 2019
.UPDATE...
Issued at 932 PM EDT Thu Jul 18 2019
Not a particularly busy evening in this CWA, at least at this
instant. Cu/stratocu field is making inroads from northern Lake MI
into nw lower MI. Some of this is bubbly enough to produce weak
returns on radar, and given relatively low cigs and moist low-
level air, suspect some of this is reaching the ground. Have
introduced some sprinkles to account.
More vigorous showers are just to our nw, in the broader Pictured
Rocks area. Not a lot of lightning here, but every once in a while
TLN is detecting a strike or two. This will bring showers and
perhaps a thunderstorm to central/northern Chippewa Co over the
next several hours.
If there is a main show tonight, it will originate with and ahead
of the broken line of convection now over southern MN. CAMS
develop additional showers/storms on the axis of and ahead of
that line, north of a stalled boundary over northern and e-central
IA. This gradually grows upscale as it presses eastward,
threatening the MBL/Ludington areas perhaps as soon as 1 am.
Clusters of showers/storms will expand a bit into sw and perhaps s
central parts of the forecast area, before weakening with further
eastward extent as storms outrun the low-level jet.
We don`t have a great deal of instability presently, with some nw
lower MI coastal counties and western Chip/Mack Cos with MlCape
values in high triple digits. And SbCape will decrease with loss
of diurnal heating. There is a plume of high MuCape values in
southern WI, and this will make some inroads into sw sections as
low-level sw flow increases. This could be enough to support some
stronger storms overnight in parts of nw lower MI. I would not
totally rule out a stray svr storm or two, but activity will be
disorganized multi-cellular in nature, and SPC has essentially
removed northern MI from the earlier marginal svr risk.
Our moist airmass (PWAT values 1.5-1.6 per 00Z APX/GRB soundings)
will be prone to heavy rainfall. Most recent RAP run keeps that
just south of this forecast area, impacting Ludington/Pentwater
etc. HRRR is wetter further north, even as far as TVC. Some 1-2"
rainfall accums seem entirely possible overnight, near/south of
M-72 and west of US-127.
&&
.NEAR TERM...(Through Tonight)
Issued at 332 PM EDT Thu Jul 18 2019
High Impact Weather Potential: Few thunderstorms possible this
through tonight. Isolated severe thunderstorm remains possible.
Pattern forecast: Current mid-afternoon composite analysis reveals
low pressure across Ontario with a warm front extending southward
through eastern upper into lake Huron...and further southeastward.
Low pressure and attendant surface boundary are expected to continue
to shift northeastward through the remainder of the afternoon into
the overnight hours continuing to leave all of northern Michigan in
the warm/muggy sector.
Attention then shifts to a secondary quasi-stationary boundary/warm
front/dewpoint boundary that`s draped across southern MN/IA through
southern WI...expected to slowly shift a bit northward tonight and
perhaps becoming the focus for additional shower and storm
development, although lots of questions remain.
Primary forecast concerns/challenges: Convective evolution and
resultant PoPs/thunder chances. Isolated severe storm?
Overall, a rather low confidence forecast moving forward this
evening into the overnight hours. Latest trends suggest the ongoing
area of showers and embedded thunderstorms across eastern upper and
Lake Huron continue to shift off to the northeast into Ontario over
the next several hours, coinciding with the continued northeastward
progression of the aforementioned warm front. This will ultimately
leave drier weather to prevail, already evident across much of
northern lower. However, SPC mesoanalysis reveals upwards of 1,500
J/kg of MLCAPE developing in its wake...likely to increase beyond
this through peak daytime heating as temperatures climb into the 80s
behind any precip (TVC at 86, CAD 86, HTL 82 degrees, etc). Main
limiting factor in additional shower/storm developing through the
remainder of the daylight hours is any large scale forcing for
ascent, which is essentially nil. While latest short-term CAMs agree
with the thought of primarily dry weather prevailing through the
evening hours, if an isolated storm is able to develop off of any
small scale forcing, bulk shear values upwards of 40-45 kts nosing
into the region would promote potentially robust/sustained updrafts
and the threat of an isolated severe wind gust. Again, this threat
is low, but the forecast area does remain in a Marginal Risk for
severe storms per SPC`s latest Day 1 Outlook.
Attention shifts to the aforementioned secondary surface reflection
expected to become situated across southern MN into southern/central
WI this evening and overnight. Additional shower/storm development
is possible along this feature later this evening across southern MI
(within SPCs Slight Risk area) - on the nose of stronger wind fields
aloft with little in the way of capping. This development may wind
up growing upscale into another MCS overnight as it shifts east-
southeastward across WI toward central Lake Michigan. Current
expectations are that convective evolution should lend the strongest
cells primarily to the south of the forecast area after 3-4 AM
Friday, although wouldn`t be the surprised if areas south of M-72
(and especially along/south of M-55), get scraped on the northern
edge of showers/storms. Worth monitoring moving forward over the
next 12+ hours, however, as any storms that are able to make it over
the lake toward the forecast area may pose a severe risk given
continued deep layer bulk shear values AOA 35-40 kts.
Mild/muggy low temps tonight in the upper 60s to low 70s for most
will give a kick start to Friday`s expected heat and potentially
dangerous heat indices.
&&
.SHORT TERM...(Friday through Saturday)
Issued at 332 PM EDT Thu Jul 18 2019
...Unsettled very warm and humid into the weekend...
High Impact Weather Potential: Very warm/humid conditions possible
for Friday with high heat indices. Marginal risk for severe storms
Friday into Saturday.
Pattern Synopsis/Forecast: Semi-permanent large scale upper level
ridging spans the southern CONUS with strong westerly flow across
the northern tier of states/southern Canada and into the Great
Lakes. Resurgence of warm/moist air into the region is underway
evidenced by several pockets of showers and thunderstorms spreading
north/eastward through the state/western Great Lakes the most
notable of which is a decaying MCS complex sliding through Lower
Michigan. Parent surface low pressure is over Ontario with some
semblance of warm front pressing eastward across Lake Superior and
Lake Huron and most of michigan now within the warm (and muggy)
sector. Secondary warm front/dewpoint boundary may be draped across
Iowa into the lower Great Lakes.
Northern Michigan and the western Great Lakes will remain entrenched
within this warm and muggy airmass for the next few days until a
cold front finally presses southward through the state on Sunday.
Several more rounds of showers/storms will impact the region. But
exact timing and location of convection is and will remain uncertain.
Primary Forecast Concerns/Challenges: Convective evolution over the
next few days...impact on cloud cover/temps/etc. Risk for severe
storms.
The latest thoughts on convective evolution is that will see renewed
development later tonight back across central Wisconsin and possibly
eastward into central and southern Lower Michigan...as the low level
jet ramps back up along and south of the secondary boundary. Thus,
I`m expecting showers/thunderstorms to be tracking eastward through
mainly Lower Michigan Friday morning and mainly impacting areas
south of M-72 before clearing the area heading into the afternoon.
Assuming we can thin out cloud cover heading into the afternoon,
temperatures should be able to warm into the upper 80s and some
lower 90s with heat indices reaching 95F to 100F, just touching
advisory criteria (100F). But given the overall uncertainty of
convective evolution and cloud cover trends, I`ll hold off on
hoisting any heat related headlines at this juncture and allow later
shifts to see how things unfold.
Pattern remains active Friday night through Saturday with additional
showers and storms likely developing in the region, and potentially
impacting the forecast area. But again, confidence in timing and
location remains low and I`ve tried to not be too cute/specific with
pops/weather at this juncture.
Severe weather potential: Sitting on the edge of strong westerly
flow aloft and within a moisture/instability rich environment, any
storms over the next few days will have the potential to be severe,
not to mention to produce some hefty rainfall amounts with PWAT
values north of 1.5 inches. Both SPC and WPC place the region within
a marginal risk for severe storms and excessive rainfall Friday and
at least Friday night...which makes sense. Will just have to play it
one day at a time.
.LONG TERM...(Saturday night through Thursday)
Issued at 332 PM EDT Thu Jul 18 2019
High Impact Weather Potential: None at this time.
A bit of a pattern shift appears on tap in the long term as large
scale upper level ridging through the southern CONUS shifts and
builds back into the western states...while downstream flow buckles
across the Great Lakes into New England. This signals the end of our
warm/humid stretch with a cold frontal passage on Sunday with
temperatures getting knocked back down into 70s to lower 80s through
next week and (more importantly) dewpoints getting suppressed back
into the 40s and 50s. Sensible weather-wise, probably not much as a
large expanse of high pressure builds and settles into the region
for much of the week. As discussed by overnight long term
forecaster, extended guidance does continue to show some sporadic
spotty precip popping throughout the week...more along the lines of
diurnally driven type showers. But plan for now is to more or less
remove most precip chances through the week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Friday night)
Issued at 1137 PM EDT Thu Jul 18 2019
Humid. Showers/storms possible overnight into early Friday, mainly
MBL and perhaps TVC.
Warm/muggy air remains in place. Pretty quiet with VFR conditions
now. Showers/storms are developing upstream over parts of northern
Lake MI and especially further west in WI. Some of this activity
will poke into nw lower MI, impacting MBL in particular, and to a
lesser degree TVC. Most of this will stay south of PLN/APN. Brief
but sharp cig/vsby restrictions possible overnight into the start
of the day Friday. The rest of Friday will be quiet and VFR,
though could be somewhat hazy.
Sw winds, mostly on the light side.
&&
.MARINE...
Issued at 332 PM EDT Thu Jul 18 2019
An area of low pressure will continue to shift northeastward through
Ontario this afternoon through tonight, pulling a warm front and
attendant tighter pressure gradient across northern Michigan. This
is expected to result in low end small craft advisory wind speeds
across portions of Lake Michigan through this evening. Another warm
front and tightening gradient arrives Friday night into Saturday,
bringing potentially more advisory level winds - although lower
confidence prevails during this time frame. With respect to
precipitation chances, there will be mainly low chances for showers
and storms with heavy rainfall and some severe storms through
Saturday. The main threats will be for damaging winds & large
hail.
&&
.APX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
LH...NONE.
LM...SMALL CRAFT ADVISORY until 2 AM EDT Friday for LMZ344>346.
LS...NONE.
&&
$$
UPDATE...JZ
NEAR TERM...MG
SHORT TERM...BA
LONG TERM...BA
AVIATION...JZ
MARINE...MG
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
328 PM MDT Thu Jul 18 2019
.SYNOPSIS...
Scattered to numerous thunderstorms in the higher terrain, and
isolated thunderstorms in the lowlands, will continue to be the
theme through Saturday. A weak backdoor cold front will push
towards the Continental Divide on Sunday, bringing deeper moisture
into the region from the east. This looks like it will bring an
uptick in thunderstorm activity across the region Sunday and
Monday, with localized heavy rainfall possible. Drier air aloft
looks to diminish thunderstorm activity heading into the middle
part of next week.
&&
.DISCUSSION...
Showers and thunderstorms have been impressively widespread this
afternoon over the higher terrain of the Gila Region and parts of
the Sacramento Mountains (notably N and S of Cloudctoft). Slow
moving storms have led to localized heavy rainfall. So far, it is
quiet in the lowlands, and despite widespread dewpoints in the 60s
this morning, much of southwestern New Mexico has managed to mix
out into the mid-40s, with 50s mostly confined to an area roughly
south and east of an ALM-LRU line. RAP13 analysis shows CAPE
values in the lowlands much higher in this area as well, with
SBCAPE >1000 J/Kg mainly over southern Otero, El Paso and Hudspeth
Counties, and the far SW corner of the Bootheel. However,
significant capping exists with SBCIN generally in the 80-120 J/Kg
range. The lack of cu development also hints at this, and a early
afternoon RAOB from WSMR HQ confirms it.
CAMS models including more recent HRRR runs suggest a few cells
will survive coming off the Sacramento Mountains into parts of El
Paso and Hudspeth County, where there are a few pockets of lower
CIN. Also, the higher terrain of the Bootheel appears to a have a
slightly better chance for late afternoon/evening thunderstorms.
Heading into Friday and Saturday, the subtropical ridge axis looks
to drift slowly northward, through we`ll remain in E to NE flow
aloft, with mostly recycled low-level moisture coming from the
south. This will likely make afternoon dewpoints and available
instability somewhat spotty and inconsistent in the lowlands, much
like today, with some areas mixing out into 40s dewpoints, and
others staying in the lower-50s. Expect good coverage of
thunderstorms in the higher terrain, and isolated coverage in the
lowlands.
On Sunday, a backdoor cold front looks to give us a boost in low
level moisture, mainly east of the Continental Divide. The upper
ridge looks to further drift northward, and NE mid-level flow
appears will be ideal for steering mountain thunderstorms over the
Sacramentos into the Mesilla and El Paso valleys. Continued moist
easterly low level flow on Monday should give us another "uptick"
day, though western areas may be more favored, especially if there
is much rainfall over eastern areas Sunday evening.
Both the ECMWF and the GFS suggest the upper ridge will drift
north of the Four Corners early next week, with NE flow pulling
drier air aloft over the Great Plains into our area, diminishing
precip coverage, especially east of the Divide.
&&
.AVIATION...Valid 19/00Z-20/00Z...
VFR conditions expected to persist with the exception of
temporary visibility restrictions due to possible TSRA. Skies
generally SCT- BKN100-130 BKN250 through period with lower
ceilings (BKN070CB) near thunderstorms. Winds 260-310 at 10-15KT
backing to 210-250 at 05- 10KT after 06Z. Further backing expected
by 18Z tomorrow under southwest flow. Confidence for VCTS is
higher at KTCS and KDMN terminals this evening, with lower
confidence at KELP and KLRU. Temporary VRB25G40KT 3SM possible
near thunderstorms.
&&
.FIRE WEATHER...
A continued monsoonal pattern is expected as we head into the
weekend, with daily thunderstorm chances. Rain chances will be
highest over mountain zones. Temperatures will be slightly above
normal with afternoon min RH in the 20-30% range over the weekend.
Weak afternoon winds will lead to Fair to Good ventilation rates
most days.
A backdoor cold front arrives on Sunday with slightly cooler
temperatures behind it. Winds will turn to the east along with
increased moisture and lift promoting more numerous thunderstorm
coverage Monday and Tuesday, with localized flooding the primary
threat.
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 75 99 76 101 / 20 10 30 10
Sierra Blanca 69 93 70 94 / 30 20 30 10
Las Cruces 71 97 70 98 / 10 20 20 10
Alamogordo 73 98 70 100 / 10 30 20 20
Cloudcroft 57 76 54 78 / 20 60 20 50
Truth or Consequences 73 99 72 99 / 10 30 20 20
Silver City 65 91 65 92 / 10 40 20 40
Deming 70 99 69 99 / 10 20 20 10
Lordsburg 70 97 69 98 / 20 20 20 10
West El Paso Metro 76 99 77 100 / 20 10 30 10
Dell City 72 99 72 101 / 20 10 30 10
Fort Hancock 76 99 77 101 / 20 10 30 10
Loma Linda 71 93 70 94 / 30 10 30 10
Fabens 75 98 76 100 / 20 10 30 10
Santa Teresa 73 98 74 99 / 10 10 30 10
White Sands HQ 74 98 73 99 / 10 20 20 10
Jornada Range 71 99 70 99 / 10 20 30 10
Hatch 71 100 71 101 / 10 20 30 10
Columbus 73 99 72 100 / 20 20 30 10
Orogrande 73 97 72 98 / 10 20 20 10
Mayhill 62 86 59 88 / 20 50 20 50
Mescalero 61 86 59 88 / 10 50 20 50
Timberon 59 82 56 85 / 20 40 20 40
Winston 62 91 61 92 / 10 40 30 50
Hillsboro 68 97 67 98 / 10 40 30 40
Spaceport 69 99 67 99 / 10 30 30 10
Lake Roberts 59 92 57 92 / 10 50 30 50
Hurley 65 94 66 94 / 10 30 20 30
Cliff 62 98 62 100 / 20 30 20 30
Mule Creek 67 94 67 95 / 20 30 20 20
Faywood 67 93 67 94 / 10 40 30 30
Animas 68 98 67 99 / 30 20 30 10
Hachita 68 97 68 98 / 30 10 30 10
Antelope Wells 68 94 68 96 / 40 20 30 10
Cloverdale 65 90 64 91 / 40 30 30 10
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&
$$
25-Hardiman / 30-Dennhardt
Area Forecast Discussion
National Weather Service Wilmington NC
944 PM EDT Thu Jul 18 2019
.SYNOPSIS...
Hot and humid weather with dangerous heat index values will
continue through the weekend and into early next week. A cold
front should push across the Carolinas late Tuesday or early
Wednesday, breaking the string of hot and humid days.
&&
.NEAR TERM /THROUGH FRIDAY NIGHT/...
As of 945 PM Thursday...One last round of convection fired up
over the past hour from just north of Conway to near
Whiteville. As low-level lapse rates continue to diminish with
the loss of daytime heating and continued convective overturning
of the atmosphere, odds are turning against any significant new
convection developing. The 00z HRRR shows current activity
dissipating, with some new showers developing around sunrise.
This late evening update featured adjustments to PoPs and sky
based on current radar and satellite trends, and to temperatures
where significant storm activity around Kingstree has pushed
temps down to 72 on the last observation. Discussion from 700 PM
follows...
Clusters of strong thunderstorms continue to affect the central
and eastern Carolinas this evening as a weak mid level trough
provides enough enough lift to unleash surface-based CAPE of
3000 J/kg. Winds aloft are modest so storm organization has been
limited to loose multicell clusters. Massed cold pools behind
the storms have produced forward-propagating linear features
with strong wind gusts the primary threat. With such warm air
aloft (freezing levels near 14000 feet) it`s unlikely hail will
be a significant threat. HREF ensembles and recent HRRR runs
indicate convection should gradually diminish this evening, with
only an isolated shower or storm possible by midnight along the
coast or offshore. Forecast PoPs have been adjusted accordingly
to focus on the cluster of storms sweeping into Williamsburg
County from the west, and on the line of showers and storms
along the seabreeze/outflow interaction from Myrtle Beach to
Whiteville.
Where heavy rain occurred earlier (like Marion, SC) temperatures
have already popped below forecast lows tonight. Once convection
dissipates, a moderate-strength southwest low level jet should
redevelop and keep the boundary layer reasonably well mixed
overnight. Although not quite as warm overall as last night, I
do think coastal and urban locations near Cape Fear have a good
potential of seeing another night of 80+ degree lows. Wilmington
has already had one such hot night this year (July 12) and may
ring up a second one if temps remain 80 or higher through
midnight tonight. A third may occur tomorrow if big storms avoid
the city.
Inland lows should generally fall to 75-78 degrees.
Other changes to the forecast were generally minor. Discussion
from 300 PM follows...
Heat advisory conditions expected again on Friday as high heat
and humidity combine to produce dangerous heat with heat indices
up over 105. A few places will near Excessive Heat Warning
criteria of 110 or higher. Temps will reach into the mid 90s
most places once again Fri with overnight lows between 75 and 80
both tonight and Fri night. The westerly downslope flow in the
lower levels should add to heat potential on Fri, but should see
more clouds around to help balance it out a bit.
Mid level trough will shift slowly eastward trying to make its
way across the Carolinas tonight through Friday. This trough
approaching from west will help to enhance convective
development in an already unstable atmosphere. All models point
at a late day spike in convection inland with activity
diminishing as it moves toward the coast closer to midnight.
Therefore best chc of greater storm coverage will be I-95
corridor late aftn and shifting toward the coast in a westerly
steering flow, but diminishing later this evening into early
overnight hour as we lose heating.
The mid level trough will remain aligned from SW to NE over the
Carolinas as it eases slightly eastward overnight into Fri. This
should help to maintain greater cloud cover and convective
activity with slightly higher SW winds through Fri. This trough
is coming up against ridge over the Atlantic, though which
should re-exert itself, especially heading into the weekend.
Depending on how quickly, should end up with limited, if any
activity heading into overnight Fri, but another hot and humid
day expected on Fri.
&&
.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/...
As of 300 PM Thursday...The latest guidance has trended drier
for Saturday but looking at model soundings profiles are similar
to previous days so I have maintained the chance pops area
wide. Not a lot of forcing is probably what guidance is keying
on but the sea breeze boundary and outflows should be enough.
Almost impossible to go with a dry forecast this time of year.
HIghs in the lower to middle 90s combined with the dewpoints
well into the 70s will most likely warrant another heat
advisory.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 300 PM Thursday...The main focus of the extended will be
on the events of the latter part of the period as guidance still
points to a decent mid level trough developing and or moving
across the Eastern U.S. Of course there is the usual wobbling of
the front and its final position but it will likely be in the
area enhancing convection. The overall trend of the forecast
remains intact, cooling temperatures with increasing pops.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 00z...Made a quick adjustment to the forecast given radar
trends with the north flank of the line of storms likely to
impact KMYR from 01-02Z. Otherwise expecting convection to
gradually diminish through the mid/late evening hours with the
loss of heating. As a result, VFR CIGs/VSBYs will dominate the
bulk of this TAF period overnight through Friday morning.
Additional convection Friday afternoon could lead to TEMPO MVFR
conditions but not enough confidence at this time to include
other than VCTS.
Extended Outlook...VFR conditions are expected outside any
isolated to widely scattered convection through Monday, with
increased chances of rain Tuesday.
&&
.MARINE...
As of 700 PM Thursday...Thunderstorms late this afternoon
affected the waters north of Wrightsville Beach. Now that the
storms are gone southwest winds are redeveloping across the this
area with speeds similar to that being observed south toward
Cape Fear and the Grand Strand area: 15-20 kt. These winds
should largely continue overnight, maintaining a choppy 5-second
dominant wave period with sea heights in the 4-5 foot range.
This is just shy of Small Craft Advisory thresholds.
Thunderstorms in the Myrtle Beach area now at 7 PM should
weaken as they move across the beaches, but outflow winds from
these storms will create a couple hours of unsteady offshore
wind directions. Models suggest only scattered showers or
thunderstorms may redevelop overnight, perhaps organization late
tonight along any landbreeze fronts that might develop off the
South Carolina coast. Discussion from 300 PM follows...
Gusty SW winds will continue into tonight in tightened gradient
between trough inland and Bermuda High. Gusts up to 20-25 kts
will continue in sea breeze and enhanced troughing through
tonight, but should diminish heading through Fri into the
weekend with a spike up in the aftn sea breeze again. The
southerly push will keep seas up between 3 and 5 ft overnight
but seas should come down to 2 to 4 ft late Fri into Sat.
Winds and seas basically a persistence forecast for the
short term and much of the extended. Southwest winds of 10-15 knots
will continue with significant seas of 2-4 feet. Some uncertainty in
the wind directions show up toward the end of the period as a front
attempts to cross the area. Wind directions become basically erratic
as is typical with a decaying front but speeds with this feature
(also typical) will be very light.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...Heat Advisory from 11 AM to 7 PM EDT Friday for SCZ017-023-024-
032-033-039-054>056-058-059.
Beach Hazards Statement from 8 AM EDT Friday through Friday
evening for SCZ054-056.
NC...Heat Advisory from 11 AM to 7 PM EDT Friday for NCZ087-096-099-
105>110.
Beach Hazards Statement from 8 AM EDT Friday through Friday
evening for NCZ106-108.
MARINE...None.
&&
$$
SYNOPSIS...TRA
NEAR TERM...TRA/RGZ
SHORT TERM...SHK
LONG TERM...SHK
AVIATION...SRP
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
316 PM CDT Thu Jul 18 2019
.SHORT TERM...(This evening through Friday night)
Issued at 315 PM CDT Thu Jul 18 2019
Short term concerns remain convective potential tonight and again
mainly late Friday afternoon/Friday night. Heat concerns remain
through Friday.
Clouds developed in the wake of last nights MCS and contaminated
the eastern portion of the CWA with moisture trapped under
building capping inversion. This kept temepratures in the 80s for
the most part with mid 90s heat indices where sunshine was more
prevalent. Mid level flow continues to stream east across central
CWA with a passing shower from time to time. Will need to mention
a low PoP for this into the evening. Cap across the boundary to
the far south remains, and cumulus is having a tough time
building. If storms intitiate, severe weather is likely with CAPE
values in excess of 4000 J/kg along and south of the MN/IA
border. Latest HRRR continue to initiate scattered convection
north of the boundary into the early evening. This may yet happen
and will continue to mention chance PoPs for this. Again, it would
become severe rapidly with hail and damaging winds the main
threat. Cannot rule out an isolated tornado near the surface
boundary early after initiation. Later this evening, if activity
does fire, expect it to move east and eventually southeast over
southeast MN. It may work into far southern metro into Eau Claire
WI area before midnight.
Morning convection should end early with an outside chance of
some elevated activity into the far north CWA during the day.
Otherwise, southern MN remains well capped with +14c mid level air
over the region south of the front. Will have to wait for forcing
along the front into the late afternoon/early evening for
development. This could be severe as well, mainly across the far
eastern areas.
Depending on overall cloud cover again Friday, heat will remain a
concern with heat indices forecast 100-106F across the heat
advisory area. That looks to be the worst case scenario for now.
With temepratures warming through the lower 90s and dewpoints in
the mid 70s. Will have to continue to monitor overall trends to
see if parts of the advisory need to be upgraded or expanded.
.LONG TERM...(Saturday through Thursday)
Issued at 315 PM CDT Thu Jul 18 2019
Showers and thunderstorms are expected to continue through Saturday
as the front sags south across the area. A pattern shift to cooler
and much drier weather begins on Sunday, and continues into next
week. Expect the heavy rain and strong/severe thunderstorm threat
from Friday night to be pretty much over by Saturday morning, as we
end up on the cool side of the boundary where instability and PW
values will be much lower. Scattered thunderstorms should continue
into saturday afternoon/evening as the rear exit region of the
departing jet lingers overhead and provides sufficient lift north of
the front. This precipitation should depart south of the area by
Saturday night, with Canadian high pressure and drier
conditions building into the region on Sunday.
The upper air pattern changes to one favoring drier and cooler
weather Sunday into next week, as ridging builds over the
intermountain west and results in northwest flow aloft over the
upper midwest. While a few impulses may ripple through the flow and
lead to slight precipitation chances, will continue to keep the
forecast dry next week given the lack of any substantial forcing
mechanisms. Temperatures look to return to more seasonable values
along with drier dewpoints in the upper 50s/low 60s. Some gradual
warming is possible towards the end of the week as the ridge axis
shifts more to the east.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1235 PM CDT Thu Jul 18 2019
Most lower levels from last nights activity continued to
develop/expand MVFR cigs over the western portion of the area.
Expect this to lift further and become VFR through 19z. Remnant
showers remain to the southwest in fast west/east flow aloft. May
continue to work east and affect mainly central MN this afternoon.
Main boundary appears to be redeveloping across far southern MN
and should be the main focus for thunderstorm development late
afternoon/into tonight. May have to include at KMKT and possible
KMSP later if boundary/activity lifts farther north. Did mention
TEMPO thunder at KEAU mainly 03z-07z period. Following this we
may see stratus/fog develop over mainly west central WI tonight
and burn off/lift through 14z FRI.
KMSP...
MVFR cigs should lift through 19z then VFR trend expected.
Thunder that develops to the south may affect the field during
the evening if it lifts farther north. Have opted to use VCTS for
now. Otherwise winds will be in south and rather light becoming
southeast into Friday. Thunder threat increase again late
afternoon/evening with approach of cold front.
/OUTLOOK FOR KMSP/
Fri...VFR night. Chc TSRA. Winds SE 5-10 kts becoming N.
Sat...VFR. Chc TSRA. Wind NE 5 kts.
Sun...VFR. Chc TSRA. Wind N 5 kts.
&&
.MPX WATCHES/WARNINGS/ADVISORIES...
WI...Heat Advisory until 7 PM CDT Friday for WIZ023>028.
MN...Heat Advisory until 7 PM CDT Friday for MNZ060>063-067>070-
074>078-082>085-091>093.
&&
$$
SHORT TERM...DWE
LONG TERM...ETA
AVIATION...DWE