Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/25/17
Area Forecast Discussion
National Weather Service State College PA
1026 PM EDT Thu Aug 24 2017
.SYNOPSIS...
A large area of Canadian high pressure will build southeast and
bring us a several day string of mainly dry and comfortably
cool weather with low humidity right into early next week.
The lone exception to these dry conditions will be late this
afternoon through the first half of tonight. Scattered showers
will develop this afternoon across the Alleghenies of northern
and western Pennsylvania, and last into early tonight across
much of central and northwestern pennsylvania as a potent upper
disturbance, represented by colder than normal air aloft passes
overhead.
&&
.NEAR TERM /THROUGH FRIDAY/...
Adjusted POPS up some, mainly to the east. Showers holding
together, given cold air aloft and rather strong dynamics.
Earlier discussion below.
Mid afternoon visible imagery shows heating of the higher
terrain of northern and western PA helping to expand a dual
bkn-ovc layer of cu and higher based strato/altocu.
As temps aloft gradually cool isolated to scattered
-shra are expected in the 21Z Thu through 04Z Friday period as
far SE as a KMRB to KSEG and KAVP line.
The primary feature that we`re focusing on that will help to
focus afternoon and evening convection and greatest
concentration of bkn-ovc ceilings will be a distinct NW/SE
tongue of higher theta-e air at 850-700 mb that was wrapping
around a low-mid level mesoscale trough across Eastern Ohio,
and extended from near KPBZ to KLBE and KCBE at 1830Z.
Latest RAP and HRRR continues to show the highest Sfc based
cape of a few to svrl hundred J/kg of cape in this area and some
light qpf-locally 1-2 tenths of rainfall from an organized area
of light to moderate showers and possibly a few low-topped tsra
as the left exit region of an 80 kt 300 mb jetlet approaches
from central/southern Ohio.
The relatively cold cloud tops could lead to some small hail
pellets in the possible/taller storms - especially across
Cambria and Somerset counties.
Collaborated with WFOs LWX and PBZ to raise previous chc pops
to likely and even categorical late today through 04Z Friday
across our southwest zones near KJST/KAOO...with high chc-low
likely in the band from near KBFD to KUNV and just west of KTHV.
Little more than some sprinkles or perhaps a brief shower
should fall east of a KMDT to KIPT line.
Current temps in the mid-upper 60s across the northern and
western mtns, and mainly low to mid 70s in the central and
southern valleys are within a deg F or two either side of
forecast highs, and are about 5 to 10F below normal over
most of the area.
Areas of bkn strato cu and alto cu lingering into the early-mid
morning hours Friday as another upper trough arrives will keep
temps tonight a few to several deg F milder than last night.
Some clearing before daybreak across the NW mtns combine with
very light winds and a large air/water delta T will support
areas of 1/2-2SM valley fog across northern PA.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH 6 PM FRIDAY/...
Friday may start out mostly cloudy in the east as the
aforementioned second upper vort max crosses that region.
However, clearing will spread in from the west and the remainder
of the CWA should see just scattered clouds through much of the
day as high pressure builds in. There could be a few short
periods of bkn high based cu/strato cu across the nrn and
western mtns in the afternoon as anomalously cool air aloft
lingers over the state.
Max temps on Fri will be very similar to today (Thursday).
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
An extended period of refreshingly cool, pleasant and dry
weather will continue through the upcoming weekend as high
pressure remains in control of the weather pattern over the
northeast quarter of the CONUS. It will feel more like early
fall than late summer. A few spots in north-central PA could
see morning lows dip into the upper 30s over the weekend.
Global models suggest isolated, terrain-induced convection may
be possible within return flow along the spine of the central
Appalachians over the weekend. However, ensemble means favor a
continuation of the mainly dry and seasonably cool pattern
through early next week, as upper level ridging out West the
supports mean troughing downstream over the Northeast.
Recent medium range model and ensemble runs depict a more
unsettled pattern developing by the end of the month. An upper
level low is projected to drop into the OH Valley, with a
frontal boundary and plume of deep moisture situated off the
Southeast coast. Latest NHC 5-day outlook has increased the
probability of tropical/subtropical cyclone formation to 40%
with a trough of low pressure currently near the Florida
peninsula - projected to drift north-northeast over the western
Atlantic and merge with the aforementioned frontal zone. The
enhanced moisture return/influx ahead of the upper low may favor
an increase in POPs late in the period.
For now, model guidance keeps the remnants of Harvey over the
Lower MS Valley to start the month of September. Beyond that,
will need to monitor the system as it should begin to lift
northeast but it`s still way to early to speculate on any
potential impacts.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Showers continue to stream through central PA this evening. The
highest concentration of showers at 01Z is along the southern
half. As such have included TEMPO groups at JST and AOO between
00Z to 02Z. Latest HRRR shows these showers should continue
through the first half of the overnight periods. With decent
instability provided by the approaching trough and moist
unstable air through the low levels, these showers should
continue as they move to the east. Weak flow through the low and
mid levels will keep these showers slow moving. As there is a
cap aloft along with dry air, am not to concerned with thunder.
As these showers move to the east along with dropping
temperatures MVFR cigs and vsbys at MDT and LNS are possible. As
such have added TEMPO groups and restrictions accordingly.
These showers should move through between 06Z to 09Z. The
cloudiness overnight could preclude the return of any fog
overnight though it should return to the usual valley locations
up north late tonight through shortly after sunrise Friday, as
some clearing occurs with light wind and very cool temps with
large air/water temp spreads.
Any borderline MVFR strato cu early Friday across the eastern
half of the state will improve to SCT-bkn035-050 by late
morning.
.OUTLOOK...
Fri-Tue...Patchy AM fog possible, mainly across northern Pa.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Lambert
NEAR TERM...Lambert/Martin
SHORT TERM...Lambert
LONG TERM...Steinbugl
AVIATION...Lambert/Ceru
Area Forecast Discussion
National Weather Service Cheyenne WY
933 PM MDT Thu Aug 24 2017
.UPDATE...
Issued at 933 PM MDT Thu Aug 24 2017
A quick update to the forecast this evening to refine late evening
precip chances based on current trends. Latest radar images show
the only area of convection that remains is near the Torrington
and Scottsbluff areas. HRRR output shows convection lingering
until 3 AM for areas in the Panhandle, so have adjusted
precipitation accordingly. No additional changes were necessary.
&&
.SHORT TERM...(This evening through Saturday)
Issued at 307 PM MDT Thu Aug 24 2017
Some showers and a few storms noted over parts of the CWA early
this afternoon, most concentrated over Kimball county and the
Snowy range area. Movement is generally east rather slowly. Expect
this to persist into this evening over these area with other
activity expected to develop over east-central Wy into the
Panhandle as a weak impulse nears the area. Convection may persist
into the night over parts of the Panhandle as some WAA develops
so have kept some pops going in that area. Good instability exists
but shear weak so a few stronger storms possible for brief
periods of time into this evening.
No significant changes seen Friday through Saturday with warm
afternoons both days. An upper high will build over the 4 corners
region Friday and hold into the weekend. Mainly dry Friday with
less instability seen though a bit of convection may develop as
another weak impulse traverses the area. Better instability
should return to mainly the Panhandle Saturday as some lee
troughing develops and allows for some moisture return and another
weak impulse drops southeast over the high plains at that time.
.LONG TERM...(Saturday night through Thursday)
Issued at 307 PM MDT Thu Aug 24 2017
Convection in the Nebraska Panhandle should quickly dissipate going
into Saturday evening, then we will probably see a fairly extended
dry pattern through midweek next week as upper ridging builds in
from the southwest pushing the shortwave track north of our area
with dry northwesterly flow pushing down across eastern Wyoming
and western Nebraska.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 638 PM MDT Thu Aug 24 2017
Only concern to aviation ops tonight will be evening convection.
Coverage has been very limited across the region, so expect little
if any impact. That said did include VCTS at KCYS, KAIA, KSNY, and
a TEMPO TS group at KCDR. Although these storms will be possible
over the next few hours, expect them to dissipate by 03z or so.
Otherwise, expect VFR conditions overnight.
&&
.FIRE WEATHER...
Issued at 307 PM MDT Thu Aug 24 2017
Mainly dry and warm weather will be over the area through the
weekend with high pressure in the upper atmosphere being the main
controlling factor. Some isolated convection possible from time to
time mainly around the mtns but other weather factors expected to
be non-critical.
&&
.CYS WATCHES/WARNINGS/ADVISORIES...
WY...None.
NE...None.
&&
$$
UPDATE...CAH
SHORT TERM...RE
LONG TERM...JG
AVIATION...CAH
FIRE WEATHER...RE
Area Forecast Discussion
National Weather Service Green Bay WI
1044 PM CDT Thu Aug 24 2017
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Friday
Issued at 240 PM CDT Thu Aug 24 2017
The latest RAP analysis and satellite/radar imagery show high
pressure stretching from northwest Ontario to the western Great
Lakes early this afternoon. Behind a departing shortwave, diurnal
cu popped up by late morning over eastern WI aided by weak moisture
fluxes off Lake Michigan and Green Bay. Though return flow continues
over the Plains, forecast concerns revolve around temps tonight as
high pressure remains over the area.
Tonight and Friday...High pressure will be centered directly over
the region tonight, leading to clear skies and light winds. Pwats
will be on par with todays 12z readings, and will not have the cloud
cover to hold up temps at all. As a result, think temps will be a
degree or two colder over northern WI, so will issue a frost
advisory for Vilas, Forest, and Florence counties. The surface high
will shift slightly to the east on Friday and allow for deeper
moisture to shift north across Minnesota and western Wisconsin. The
eastern edge of this deeper moisture will likely reach into central
WI during the afternoon, which should lead to a higher coverage of
cu. Any precip chances should remain to the west of the region,
however. Highs will be a couple degrees warmer than todays readings.
.LONG TERM...Friday Night Through Thursday
Issued at 240 PM CDT Thu Aug 24 2017
Focus in the long term will be on precipitation timing Friday
evening through the weekend, along with lingering chances early
next week.
Showers should be confined to western Wisconsin late Friday
afternoon. There are some model timing difference on when/if
precipitation will reach the western forecast area (Vilas County
south through Waushara County) Friday evening, but overall trends
show low level moisture and WAA and the RRQ of a weak upper jet
passing by Friday evening through Friday night. Therefore, kept a
chance of showers in the far west. High pressure influence will
still keep the eastern forecast area dry during this time.
Rain chances slowly spread east Saturday afternoon and evening as
the main low pressure system moves closer. Rain becomes more
likely Saturday night into Sunday as the mid-level shortwave
approaches northern Wisconsin. Medium range models are in general
agreement that this energy stalls out over Wisconsin Sunday into
Monday, and then dives south later Monday. This will result in
periodic shower chances through Monday. PWats are around 1.50
inches at times Sunday, which is about half an inch above
climatology normals. Did raise QPF values slightly on Saturday
night/Sunday morning as some heavier rain is possible at times.
Thunderstorm potential looks minimal as instability is not overly
impressive. MUCAPES are mainly around 200 to 500 J/kg Sunday
afternoon, so a few isolated thunderstorms are not out of the
question. On Monday, any thunder would likely be confined to
east- central Wisconsin as a small amount of instability lingers
around there.
Beyond Monday, the rest of the week looks quieter. Some
afternoon showers are possible Tuesday, and a quick moving
shortwave will bring a chance of showers Wednesday afternoon and
evening, but the majority of the time will be dry.
High temperatures will be cooler than normal through Monday, and
then near normal for the rest of the period. Lows will be
slightly below normal on Saturday morning, then fairly mild for
late August.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1034 PM CDT Thu Aug 24 2017
Canadian high pressure will bring VFR flight conditions to most
of the region through the TAF period, with the possible exception
of patchy ground fog late tonight over north central WI. Mostly
clear skies and light winds are expected through the period.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Frost Advisory until 7 AM CDT Friday for WIZ005-011-012.
&&
$$
SHORT TERM.....MPC
LONG TERM......KLB
AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service Wilmington NC
1004 PM EDT Thu Aug 24 2017
.SYNOPSIS...
A stalled front will bring scattered showers and storms tonight,
but canadian high pressure will bring cool temperatures and dry
weather this weekend on increasing northeast winds. We will be
watching the tropics for possible development of low pressure
off the Southeast coast early next week which could bring
rainfall back into the forecast as early as Monday and Tuesday.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 1000 PM Thursday...Mainly due to convection across the Pee
Dee Region, the front has been pushed well south of Marion and
Florence, SC and is moving into Williamsburg county now. East to
northeast winds now reported at FLO and MAO are proof of this.
Along the coast we haven`t had any impetus (yet) to get the
front moving and it remains stalled across southern New Hanover
and Brunswick counties in North Carolina. A broad swath of
northeasterly winds across the Outer Banks and the Crystal Coast
should begin to push the boundary southward within the next
couple of hours, with no significant changes to the previous
wind forecast needed.
Showers and t-storms are concentrated in an impressive cluster
near the Florence-Williamsburg border now. These should move
southward to the Santee River over the next few hours. Plenty of
elevated instability within a humid airmass behind the front is
creating scattered slow-moving showers all across SE North
Carolina and Horry County, SC. It`s possible these clusters
could grow into locally heavy rainmakers over the next few hours
as they meander within slow, generally convergent low-level
winds surrounding the front. Although my areal QPF across this
region is a one-quarter to one-third of an inch, undoubtedly
there will be a few spots that pick up 2 inches or more in the
next few hours.
Discussion from 730 PM follows...
The surface front extends from roughly Southport, NC across
northern Horry County, SC to near Marion and Florence, then
southwestward into a weak surface low near Augusta, GA along the
Savannah River. A rather impressive area of convection that
developed earlier this afternoon near and north of Fayetteville,
NC is probably associated with convergence along the frontal
surface at 850 mb which is sliding southward. Mid-level winds
are stronger than one might expect in August which has increased
0-6 km bulk shear values to around 30 knots. With modest CAPE
values of 1000-2000 J/kg latest mesoanalysis is showing some
bullseyes of Bulk Richardson numbers of 40-60 which may explain
some of the brief supercellular signs one cell displayed earlier
in Dillon County, SC.
The HRRR has been performing quite well the past few days,
(certainly better than the 18Z NAM today) and appears to have
initialized well on its past few runs. The latest run shows the
current convective cluster sagging southward into the Myrtle
Beach area between 930-1100 PM. Forecast PoPs were raised to
60-100 percent near and along the path of this cluster through
late evening.
The surface front should pick up some southward momentum
overnight and move offshore and south of the Santee River. This
won`t clear us out as the shallow slope of the frontal
surface will maintain mass convergence and unstable conditions
aloft, particularly across coastal South Carolina and near Cape
Fear. Scattered showers could continue across these areas
through late tonight.
No significant changes were made to forecast lows: 70 to lower
70s for most areas, except some upper 60s across interior SE
North Carolina.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 300 PM Thursday...Temperatures will run a bit below climo
through the period as high pressure wedges in from the northeast
behind an offshore stalled frontal boundary. Sky cover is probably
the trickiest part of the forecast. These wedges can be quite cloudy
even though mid levels should dry adequately. There will be an
inland/coastal gradient in moisture, highest along the coast due to
the offshore boundary. Similarly it`ll be tough to rule out a
sprinkle in those areas but measurable rainfall seems very
unlikely.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 300 PM Thursday...A stationary front will be located
well offshore and S of the area Sun with an area of low pressure
positioned on the front, but well offshore. High pressure will
be ridging across the Carolinas from New England. A broad area
of disturbed weather to our S continues to be monitored and a
tropical system may begin to take shape early next week. The
longer range models that do try to develop the system, do not
indicate much in the way of vertical depth. Much too early to
say what impacts, if any, will be felt on land across the
eastern Carolinas. Will show dry weather continuing into Sun and
then show increasing POPs Mon and Tue, highest along and near
the coast. The rainfall forecast does hinge to a large degree on
low pressure development, or not, off the Southeast coast and
the interaction of this low with the front. Otherwise, high
pressure to our N will take on a wedge configuration for a time,
keeping temps near or below normal. Highs will be in the mid
80s with some locations only in the lower 80s early in the week,
especially along the coast. Lows will be in the mid 60s to near
70 for much of the week, trending higher at the end of the
period.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
As of 00Z...The surface front lies in between ILM and CRE along
the coast of the Carolinas and extends westward to very near
FLO. A line of showers and thunderstorms extending from LBT to
FLO should move southward over the next couple of hours,
affecting the CRE and MYR airports as soon as 02Z. MVFR
conditions may drop briefly to IFR, especially at LBT where the
heaviest storms are currently located at 00Z.
Although the surface front should move southward late tonight,
the shallow slope of the frontal surface aloft should maintain
an environment suitable for the redevelopment of scattered
convective showers across coastal South Carolina and perhaps
coastal North Carolina through most of the night.
Drier air building southward after daybreak Friday should lessen
the potential we`ll see convective showers or storms develop.
VFR conditions should prevail.
Extended Outlook...MVFR ceilings could linger, especially near
the coast Friday evening. VFR through the weekend. Showers may
increase beginning Monday as a coastal low passes well offshore.
&&
.MARINE...
NEAR TERM /THROUGH FRIDAY/...
As of 1000 PM Thursday...The front has moved very little over
the next few hours, however the appearance of a broad swath of
northeasterly winds over the Outer Banks and the Crystal Coast
region means the front should begin to move southward within
the next couple of hours. Radar reveals scattered showers
developing near and just north of this front, and I see no
reason why more showers and perhaps thunderstorms won`t develop
through the night as the front dips southward. High moisture
content of the atmosphere means these showers and storms will
drop heavy rainfall with significant visibility restrictions
expected for mariners.
Discussion from 730 PM follows...
The surface front has actually returned northward over the past
several hours, roughly extending across Kure Beach, NC just
north of Cape Fear. Virtually all model guidance indicates this
northward drift should end shortly with the front returning
southward overnight, passing through the coastal waters and
south of the Santee River by daybreak Friday. This should turn
the southerly winds in place across most of our forecast area
northerly to northeasterly, but wind speeds should remain
generally 10 knots.
A line of showers with some gusty winds across the Interstate
95 corridor is sagging southeastward and should make it into the
Myrtle Beach area around 1000 PM this evening. Model show this
convective activity will likely be joined by new showers and
embedded thunderstorms throughout the night, especially south of
Cape Fear.
SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 300 PM Thursday...Some pretty unsettled weather on tap for not
only the short term but well beyond as well. Northeasterly gradient
winds in place as high pressure noses in behind the offshore stalled
frontal boundary. The strength of the gradient will be affected by
the highly uncertain fate of low pressure that will develop over
Florida and start moving northeast. This low may be tropical,
baroclinic, or a hybrid, its thermal structure but one thing lending
to the uncertainty. Currently its development seemingly hindered by
the outflow from the rapidly intensifying Harvey. Regardless the
system will lead to Advisory-worthy wind and seas from Saturday
on.
LONG TERM /SUNDAY THROUGH TUESDAY/...
As of 300 PM Thursday...Persistent and brisk NE winds will
likely require a Small Craft Advisory for a good portion if not
all of the period. The rather tight pressure gradient will be
the result of strong high pressure ridging down into the
Carolinas from the N and an offshore front and area of low
pressure. Will be watching the tropics early next week for the
possible development of tropical low pressure off the Southeast
U.S. coastal waters. NE winds will be around 25 kt Sun into Mon
and may linger longer or even strengthen depending on any future
tropical development. Seas will be 5 to 7 ft and perhaps up to
8 ft. Seas too may build higher depending on any future tropical
development.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...RJD
NEAR TERM...TRA
SHORT TERM...MBB
LONG TERM...RJD
AVIATION...TRA
Area Forecast Discussion
National Weather Service Wilmington OH
936 PM EDT Thu Aug 24 2017
.SYNOPSIS...
High pressure and a seasonably cool airmass will be in place
across the region through Friday, before it works off to the
east over the weekend.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
The only real forecast concern for tonight is with the broken
area of 7kft-9kft clouds moving through the northern half of the
ILN CWA. Roughly corresponding to around 750mb-700mb, most of
the models have tried to dissipate this moisture a little too
quickly, though recent HRRR runs have allowed a little more
persistence. Overall, still thinking that this will eventually
break up and/or dissipate to some extent over the next several
hours, but mostly cloudy conditions are expected for a while
longer.
After looking at several recent model runs for T/Td and
comparing to current conditions, the best course of action
appeared to be leaving the current forecast essentially
unchanged. Surface dewpoints are a little higher in the south,
so some river valley fog can be expected on the Ohio / lower
Scioto etc. Still expecting lower to middle 50s for min temps,
with an outside shot at some upper 40s in the northern CWA if
the clouds break up.
Previous discussion >
H5 s/w will affect the region for the first part of tonight,
before it swings east into the Appalachians aft 03Z. This will
provide pva and upper lift, which might cause the clouds to
linger a little longer than a normal diurnal pattern would
suggest. Therefore held onto a little more cloud cover from 00Z-
03Z than previous forecasts. After 00Z, went with mostly clear
skies.
With the airmass modification and the lingering cloud cover,
went with lows in the lower to mid 50s tonight.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
On Friday, the region remains under nw H5 flow, but there
doesn`t appear to be any definitive s/w, so while some diurnal
cu is expected tomorrow, it shouldn`t be as much as today. The
clouds should dissipate tomorrow evening leaving mostly clear
skies again.
Highs on Friday, should be in the upper 70s to lower 80s. Lows
Friday night will be a few degrees warmer, in the upper 50s to
lower 60s.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
The center of high pressure over the Great Lakes will move off to
the east over the weekend, but it will continue to extend/influence
our weather with dry conditions. Highs in the 70s on Saturday will
warm slightly by Sunday into the upper 70s to the lower 80s.
The upper level flow will become amplified across the CONUS as we
head into next week. A mean mid level ridge will develop over the
western U.S. as an upper level trough digs into the Great Lakes and
Ohio Valley, moving very slowly east through mid to late week. This
setup will increase the chances for precipitation Monday into
Tuesday with the threat lingering into at least Thursday. The threat
for thunderstorms will be tied more to the diurnal cycle, especially
by Wednesday/Thursday. Temperatures will be slightly below normal
for highs and close to normal for lows.
Given the amplified pattern, much remains to be seen as to whether
the remains of Harvey move northeast into the Ohio Valley region by
next weekend. We will continue to monitor.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Though diurnal cumulus will generally dissipate this evening,
some larger stratocumulus patches will likely hold together over
the DAY/CMH/LCK TAF sites going into the next 4-8 hours. Winds
will become light, but should remain generally out of the north.
River valley fog is expected overnight, including IFR conditions
at LUK.
No significant weather is expected on Friday, with diurnal
cumulus and NNE flow at 10 knots or less.
OUTLOOK...Thunderstorms are possible Monday into Tuesday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...JGL/Sites
NEAR TERM...Hatzos/Sites
SHORT TERM...Sites
LONG TERM...Hickman
AVIATION...Hatzos
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1044 PM EDT Thu Aug 24 2017
.UPDATE...
Issued at 1044 PM EDT THU AUG 24 2017
GOES 16 products showcasing high clouds moving east toward the
Lake Cumberland region this hour. Otherwise clear skies are the
story tonight, as we remain under the control of surface high
pressure to the north. Overall temperatures in the valleys have
been cooling quickly with temperatures in the upper 50s and here
at JKL we remain at 64 degrees at 0240Z. Models are struggling
with temperature trends as usual but the hires ARW had the best
trend albeit too low. Only minor changes needed for high clouds
and temperature trends.
UPDATE Issued at 726 PM EDT THU AUG 24 2017
Minor update to deal with latest obs and trends. Otherwise
forecast is on track.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 355 PM EDT THU AUG 24 2017
19z sfc analysis shows high pressure over the region. For eastern
Kentucky, this has kept temperatures on the cool side of normal
today with comfortable humidity levels. Currently, temperatures
are running in the mid 70s most places with dewpoints in the mid
50s. Winds have been generally from the northeast at 5 to 10 kts
with occasional higher gusts.
The models are in good agreement aloft with the longwave pattern
affecting the region through the short term. They all agree that
the core of the eastern trough through the Great Lakes will shift
east and away from the area tonight with heights rebounding and
the mid level northwest flow relaxing. This trend continues into
Saturday morning as the area will be in between a developing
trough to the northwest and the upper levels of `Harvey` well off
to the southwest. Given the agreement will favor a general model
blend with a lean toward the HRRR and NAM12 for details.
Sensible weather will feature capital weather days with plenty of
sunshine and cool conditions for mid to late summer. The lower RH
will be noted as well in the afternoon. Each night we can expect
mostly clear skies and a good radiational cooling environment
allowing for moderate ridge to valley temperature splits. Also,
look for valley fog to develop and become dense near the rivers
toward dawn each morning.
Have used the CONSShort as the starting point for most grids with
the most significant adjustments made to temps at night to
account for the terrain distinctions. As for PoPs, basically
zeroed them out in the short term - in line with all guidance.
.LONG TERM...(Saturday through Thursday)
Issued at 308 PM EDT THU AUG 24 2017
The high pressure ridge will stay across the region through
Sunday, keeping eastern Kentucky dry. The weather will turn more
unsettled heading into next week although quite a bit of
uncertainty remains on what happens with the remnants of Hurricane
Harvey. At this point it does looks like a mid level trough will
push east across the great lakes Monday and Tuesday, bringing an
increased threat of showers and storms to eastern Kentucky. As we
head into mid week, models really diverge on scenarios. If the
tropical moisture spreads north, then we may keep rain around
through much of the week. However, the 12z GFS has the system
remain over the Gulf coast states until it weakens and dissipates
and never brings that moisture northward. Right now, just too much
uncertainty involved to get lost in the details, and will just
keep the pops broad brushed through much of the week until
confidence can improve.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 717 PM EDT THU AUG 24 2017
An area of surface high pressure to our north will remain the
controlling factor in the weather through the TAF period. Most of
the afternoon CU has dissipated and we are seeing mostly clear
skies. These clears skies and high pressure will set the stage for
valley fog overnight. The overall affect on TAF sites will be
less given the drier air that is advecting into the region,
However, did put a MVFR VIS in for SJS/SYM where fog could move
into these sites toward dawn from the valley. There will also be
some high clouds moving east into the region based on GOES 16 SAT
data, but these will remain in the VFR range. Then model soundings
suggest a few diurnal CU are possible by Friday afternoon, but
the coverage is expected to be lass than today and remain at
around 5 kft. The winds will be light out of the NE for the
period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...DJ
SHORT TERM...GREIF
LONG TERM...KAS
AVIATION...DJ
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
627 PM CDT Thu Aug 24 2017
.SYNOPSIS...
Issued at 321 PM CDT Thu Aug 24 2017
H5 analysis this morning had high pressure over the
Bahamas, as well as Baja California. In between these highs,
hurricane Harvey was beginning to show up on the latest H5 chart and
was centered about 300 miles southeast of Corpus Christi Texas.
Further north, a trough of low pressure extended from Quebec south
into the Mid Atlantic. Upstream of this trough, a shortwave trough
of low pressure was present over western Wisconsin with a secondary
wave noted over nern Missouri. Ridging was west of the trough, and
extended from Montana north into Nunavut Canada. Across the
intermountain west, very weak mid level flow was present with
numerous weak shortwaves noted. As of 12z this morning, shortwaves
were noted over northern Utah, eastern Utah, western New Mexico and
Idaho. Across western and north central Nebraska, a weak disturbance
was lifting across the area and has led to abundant mid level
cloudiness this afternoon. Some light rain showers and evening an
embedded thunderstorm or two has occurred this morning and into the
early afternoon hours.
&&
.SHORT TERM...(This evening through Friday)
Issued at 321 PM CDT Thu Aug 24 2017
Precipitation chances over the next 24 hours are the
main forecasting concern. Low level moisture has definitely
increased across the area over the last 24 hours as dew points were
in the upper 50s and 60s across western and north central Nebraska.
Fcst cape this afternoon is expected to reach 2000 to 3000 J/KG from
southwest into central and northeastern Nebraska. At the surface, a
weak convergent zone was present from near O`Neill, to Broken Bow to
north of North Platte, to the sern Nebraska Panhandle. As the upper
level wave, currently over western Colorado, crosses the Rockies
this afternoon, am expecting thunderstorms to fire across the high
plains of Colorado and Sern Wyoming late this afternoon. As this
feature lifts into eastern Colorado, there will be an increased
threat for showers and thunderstorms this evening. At this time, am
expecting the best chances for thunderstorms INVOF the low level
convergence zone from swrn into northeastern portions of the
forecast area. In these areas, the inherited forecast had the
highest pops left the forecast as is, decreasing pops in the north
central and northwestern zones. Deep layer shear this evening is
fairly meager on the order of 20 to 25 KTS so there will only be a
meager threat for severe storms. However, with PWATS in the 1.0 to
1.5 inch range along the boundary, heavy rain could be an issue this
evening. Overnight, convection will push east, exiting the area
after midnight. Overnight tonight into Friday morning, the
short range model solutions lift the surface boundary north into
South Dakota. Am expecting fairly early thunderstorm initiation
Friday afternoon as there is little or no cap present by 21z. Will
favor the highest pops in the north INVOF the surface boundary.
.LONG TERM...(Friday night through Thursday)
Issued at 321 PM CDT Thu Aug 24 2017
Mid range...Friday night into Sunday: The threat for
thunderstorms will continue Friday night into Sunday as a couple of
weak upper level disturbances traverse, South Dakota and Nebraska.
Thunderstorms are expected to be ongoing across South Dakota and
northern Nebraska Friday evening. This activity will shift into
eastern Nebraska overnight. On Saturday a second upper level
disturbance will track from the Panhandle into central Nebraska with
increased chances for thunderstorms Saturday afternoon and evening.
This will be followed by one final weak disturbance on Sunday.
Sunday night through Thursday: A pattern shift will begin to take
shape late Sunday into next week. A broad ridge of high pressure
will build across the western CONUS. This will place the forecast
area in due north mid level flow, which will greatly limit any
pcpn chances. Highs will generally be seasonal as the warmest air
will reside off to the west of the forecast area.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 627 PM CDT Thu Aug 24 2017
The forecast follows the HRRR model but with low confidence as all
of the rapid refresh models have been struggling predicting storm
development and evolution. The good news is none of the models
except the RAP show VFR conditions but it is possible MVFR cigs
will develop in the wake of tonight`s thunderstorm activity.
At some point this evening, the thunderstorms should begin to
grow upscale toward I-80 and S/Ncntl Neb and become numerous. The
storm activity should last most of the night and exit the region
around 12z Friday.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...CDC
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
922 PM EDT Thu Aug 24 2017
.SYNOPSIS...
A stalled front near the North Carolina/South Carolina border
will move little overnight. Strong high pressure will build in
from the north Friday through Sunday. An area of low pressure is
forecast to develop along the stalled frontal boundary off the
Florida coast Sunday and slowly lift northeast along the
Southeast coast early next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 920 PM Thursday...Cooler E/NE flow prevails across
eastern NC in wake of the cold front which crossed the area this
morning. With the loss of diurnal heating, widely scattered
shower activity over our area has dissipated this evening. The
HRRR and NSSL WRF do indicate convection developing mainly
offshore of the SE coast overnight as a weak low moves along the
stalled front offshore. If this activity does develop it should
remain mainly offshore so will indicate more of drying trend
inland and north with only slight chance PoPs SE coast. The
drier airmass in place across the region will lead to cooler low
temps with readings in the mid/upper 60s northern and central
CWA with lower 70s closer to the coast.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
As of 255 PM Thursday...High pressure will ridge south from the
Great Lakes Friday with an NE/ENE flow regime across eastern NC.
Temperatures and especially dewpoints will be a little below
normal for Friday with highs in the low/mid 80s and dewpoints
over all of the CWA in the mid/upper 60s. Model time-sections
should drying in the boundary layer and very dry air above 700
mb, but deep moisture linger in the 850-700 mb layer, so would
expect to see scattered to broken clouds at times on Friday
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
As of 250 PM Thur...Below normal temps expected this weekend and
through most of next week. Unsettled conditions are expected
along the coast this weekend, while it will be mostly dry
inland. More widespread rainy conditions are likely next week
as we continue to watch for the possible development of a
tropical low along the SE coast, though much uncertainty remains
regarding this system.
Friday Night through Sunday...Strong high pressure will build
behind a cold front that is expected to stall in the vicinity
of the Gulf Stream. Still, widely scattered showers will
possible along the coast, while further inland it should be
mostly dry. Low level thickness values, and NE flow, support
below normal temps with highs in the upper 70s to mid 80s and
overnight lows in the low/mid 60s inland and mid 60s/70 degrees
along the coast.
Monday through Thursday...Models continue to show possible
tropical low development along the stalled frontal boundary off
the SE coast this weekend into the middle of next week. Much uncertainty
remains on how this system will evolve, given how far out in
time, and varying model solutions/lack of run to run
consistency. Low is forecast to strengthen off the FL coast Sat
night and Sun, slowly lifting NE Mon through Wed. Looking at the
12z guidance suite, the CMC is still the strongest and brings
the system closest to the NC coast, while the ECMWF and GFS
offer a weaker solution, and are slightly further off the
coast. More widespread precip is possible Monday onward, but
will keep chance PoPs with so much uncertainty still to be
resolved. High temps through the period, generally in the upper
70s to low 80s, with overnight lows 60-70 degrees.
&&
.AVIATION /01Z FRIDAY THROUGH TUESDAY/...
Short Term /through Friday/...
As of 655 PM Thursday...Main question is whether ceilings will
lover from current VFR with high Cirrus clouds and scattered
high based Cumulus currently across the area. Although the low
level flow is out a favorable easterly direction, I`m not really
seeing a strong signal in any of the guidance for either fog or
low ceilings overnight. Thus will issue a VFR forecast and
indicate scattered MVFR clouds late. Friday diurnal heating is
expected to promote widespread Stratocumulus clouds with VFR
bases.
Long Term /Friday Night through Tuesday/...
As of 320 PM Thur...Predominant VFR conditions expected through
most of the period. Rain showers and isolated thunderstorms
will be possible Monday and Tuesday with the best chances closer
to the coast. This could lead to some brief sub-VFR conditions.
&&
.MARINE...
Short Term /Tonight and Friday/...
As of 920 PM Thursday...High pressure building into the waters
will continue to produce NE/E flow 10 to 15 kts with occasional
gusts to 20 kt through Friday. Seas are expected to remain 3-4
feet through Friday.
Long Term /Friday Night through Tuesday/...
As of 325 PM Thur...Strong winds and dangerous seas expected
to develop this weekend and continue into next week, with the
potential for tropical low development along the southeast
coast.
Strong high pressure will build in from the north Friday through
Sunday. Models continue to show the potential for tropical low
development along the stalled frontal boundary off the SE coast this
weekend into early next week. There is still quite a bit of
uncertainty given how far out in time and the varying model
solutions and lack of run to run consistency. Winds initially ENE 15-
20 kts will increase Saturday night, becoming NE 20-25 kts. Winds
continue to be NE/ENE 20-25 kts through Tuesday, with 25-30 kts
possible across the central waters Monday night. Seas will initially
be 3-5 ft Saturday, but will quickly build to 4-6 ft across the
central and southern waters Saturday night. All coastal waters will
build to 5-8 ft Sunday afternoon, and then 6-10 ft Monday, with the
highest seas over the outer central waters. Seas will begin to calm
some on Tuesday dropping to 6-9 ft.
Given the uncertainty on how this system will evolve, mariners
should continue to monitor the forecast over the next several days.
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...Beach Hazards Statement from 8 AM EDT Friday through Friday
evening for NCZ095-098-103-104.
MARINE...None.
&&
$$
SYNOPSIS...JME/CTC
NEAR TERM...JME/CTC
SHORT TERM...CTC
LONG TERM...SGK
AVIATION...JME/CTC/SGK
MARINE...JME/CTC/SGK
Area Forecast Discussion
National Weather Service New York NY
1050 PM EDT Thu Aug 24 2017
.SYNOPSIS...
Canadian high pressure will gradually build through Saturday,
and dominate into Monday and perhaps Monday night. Offshore low
pressure to the south may impact the area Tuesday into
Wednesday, especially along the coast, while the high remains to
the north and west. A weak cold front will approach on
Thursday.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Radiational cooling proving to be efficient this evening just
like the previous evening for some locations. Clouds have been
minimal across much of the region and with light winds once
again, has led to the efficient radiational cooling.
Temperatures have not lowered as much where there has been more
clouds. The radiational cooling will be mitigated though
overnight when clouds increase from the west with the passage of
the shortwave. Overall, just some slight adjustments with
temperatures and dewpoints with otherwise no other remarkable
changes made.
Surface high pressure builds across the Great Lakes region tonight.
Aloft, shortwave and associated PVA passes overhead overnight.
Enough dry air along with low/mid level moisture expected to be
rather shallow should preclude any rain from reaching the ground
for our area, although a few late night sprinkles are possible.
An isolated shower cannot be ruled out. The HRRR model indicates
some light shower activity towards daybreak Friday just missing
the forecast region to the SW.
Cool air remains in place, but broken clouds should prevent ideal
radiational cooling, thus resulting in lows from the low 50s in
rural and interior locations to the mid 60s near NYC Metro.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/...
Initial shortwave passes Friday morning, with overall trough
remaining across the northeast. Surface high pressure builds east
across New England through this time frame providing dry
conditions. However, with center of high pressure still well
north and west of the region and with a cold pool lingering
aloft, the daytime surface warming will initiate development of
diurnal cumulus clouds. Bufkit indicates these clouds between
6-9kft to become scattered to broken coverage in the afternoon
and could linger along the coastal sections into Friday evening.
However, think with the loss of daytime heating Friday night, the
trend will be for generally clearing skies with the loss of
diurnal instability. Clear skies still expected on Saturday too
with the center of high pressure moving within closer proximity
of the region.
Temps look to remain at or below average.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
A large high pressure system covering much of eastern North America
should continue to dominate through at least Monday, possibly into
Monday night. Temperatures during this time will run a few degrees
below average, more so at night given radiational cooling under
mostly clear skies and fairly light winds.
Uncertainty then increases quite a bit as a very complex scenario
develops, with a weak omega block developing from the northern
Plains eastward to the Canadian maritimes, and presence of a
developing low of uncertain characteristics along the Southeast
coast. GFS/ECMWF show this low remaining well out at sea and looking
more baroclinic or subtropical in nature, with no more than a
moderate ENE flow developing mainly along the coast, while the last
couple of runs of the GEMnh offer more concern for a potential
tropical impact or close call. That latter solution, while an
outlier as have been most longer range GEMnh forecasts of
tropical development this season, would be plausible if the
low remained completely tropical in nature and separate from a
frontal boundary to its north, and if the upper high over the
western Atlantic phased with that of the omega block over the
Northeast and inhibited out-to-sea progress. That said, even if
the low were to be more baroclinic in nature, past experience
has often shown that offshore lows forecast by the global models
often take tracks closer to the coast in the presence of
blocking and/or an upper trough to the west. With all that in
mind, have forecast increasing ENE winds mainly along the coast
and low chance PoP for Tue night into Wed, and anticipate at
least a high risk of rip currents during this time if not high
surf. For any potential tropical development of this system,
please refer to NHC outlooks.
This low should pass off to the east by Thursday, with a return to
near average temperatures as a weak cold front approaches from the
NW.
&&
.AVIATION /03Z FRIDAY THROUGH TUESDAY/...
A vigorous shortwave passes through late tonight with little
impact except some increasing cloud cover. High pressure then
builds in across the region Friday into Friday night.
VFR thru the TAF period. SHRA/TSRA over central PA this evening
are expected to dissipate as they approach the NYC/NJ metro
terminals late tonight/early Fri morning.
SCT-BKN cu development likely at 5 to 7 kft Fri afternoon.
Light N/NW winds Friday morning, likely back to the W for
south coastal terminals during the afternoon. Low prob for
S/SSW sea breeze development at KJFK/KISP Fri aft, with moderate
potential for SW sea breeze at KBDR/KGON.
NY Metro Enhanced Aviation Weather Support...
Detailed information...including hourly TAF wind component fcsts
can be found at: http:/www.weather.gov/zny/n90
KJFK TAF Comments: Low prob of southerly sea breeze Fri
afternoon. Occasional W/WNW gusts 15 to 20 kt possible in the
afternoon.
KLGA TAF Comments: Occasional NW gusts 15 to 20 kt likely in
the afternoon.
KEWR TAF Comments: Occasional WNW gusts 15 to 20 kt likely in
the afternoon.
KTEB TAF Comments: No unscheduled amendments are expected.
KHPN TAF Comments: No unscheduled amendments are expected.
KISP TAF Comments: Low prob of SSW sea breeze Fri afternoon.
.OUTLOOK FOR 06Z SATURDAY THROUGH TUESDAY...
.Saturday Night-Tuesday...VFR. E/NE winds.
&&
.MARINE...
High pressure builds across the waters through Saturday. Winds
remain rather light through the period, with a predominate N to NW
flow expected tonight and Friday, then NE/E Saturday. The
development of afternoon troughs may result in winds shifting for a
time both Friday and Saturday.
Ocean seas expected to remain 3 ft or less, with 1 ft or less across
non ocean waters through Saturday.
With high pressure to the north and low pressure to the south, ENE
flow should increase early next week. SCA conditions, first in
the form of hazardous seas, are possible on the ocean waters as
early as Sunday night, and appear more likely Mon into Tue. Wind
gusts up to 25 kt are also likely on the ocean on Tue.
&&
.HYDROLOGY...
No hydrologic impacts are expected through early next week.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...Goodman/PW
NEAR TERM...JM/PW
SHORT TERM...JM/PW
LONG TERM...Goodman
AVIATION...NV
MARINE...Goodman/PW
HYDROLOGY...Goodman/PW
Area Forecast Discussion
National Weather Service Mount Holly NJ
930 PM EDT Thu Aug 24 2017
.SYNOPSIS...
Canadian high pressure will build southward into the region through
this weekend before progressing offshore around the middle of next
week. This high will bring a period of dry and seasonably cool weather
to the Mid-Atlantic through at least the beginning of next week. A
tropical or subtropical low is expected to develop east of the Florida
coast this weekend and lift slowly northeastward off the East Coast
next week. At this time, the system is expected to remain well southeast
of the area.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Dirunal cu has dissipated with loss of daytime heating. As a
result, strong radaitional cooling conditions have developed due
to the combination of clear skies and light to calm winds. Temps
across much of the forecast area have dropped into the mid 60s,
but some parts of NJ are down into the low 60s, and the Poconos
have dropped into the 50s. Can expect temps to drop off several
more degrees through this evening.
H5 trough with strong shortwaves moving through western NY and
PA and will pass through the region after midnight tonight. This
will bring a BKN-OVC mid-deck with the approach and passage of
that trough.
HRRR continues to bring precip through the region during the
overnight hours, but this seems overdone compared to the 18Z
NAM/18Z GFS/12Z ECMWF. 18Z CMC-GDPS has some light precip as
well, but the overall trend is to keep things generally dry.
Will carry isolated showers/sprinkles across the Lehigh and
Delaware Valleys, mainly from after midnight through the pre-
dawn hours of Friday.
When the clouds return later tonight, temps should hold steady
or slowly rise.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
Partly to mostly sunny. Seasonable. Max temps 1 to 5 degrees
below normal. 850 temps maybe 1C less than today so temps 1 to
2F cooler than what occurred on Thursday. Light northwest winds
except seabreezes developing on the coast.
A couple of models show isolated light shower potential but
now, we are not forecasting any sprinkle activity since we`re
unsure where it might occur, if at all.
This forecast was a 50 50 blend of the 12z/24 GFS/NAM MOS.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
An extended period with fair weather will continue in the long term.
High pressure will remain in control of the weather as it slides
across southern Canada and then off into the Atlantic early next
week. The models are in general agreement with the above situation.
The GFS model is showing some light precip near the shore areas
Saturday with the low level flow being onshore at that time. I don`t
feel confident enough with this attm to raise pops into the slgt chc
range. Cloud cover across the coastal areas was increased however.
Temperatures will be a couple degrees below normal for late August,
overall pleasant for this time of year.
Next week, the onshore flow with the retreating high and an upper
trough developing across the east U.S. will result in increasing
chcs for clouds and showers. We therefore have continued with the
slight chc or low chc pops for most areas at those times. A sub-
tropical low over the east coast towards the middle of next week,
should remain far enough away to keep any significant showers
activity out of our CWA. This will be something to watch however.
Temperatures are expected to stay near seasonal norms, with more
humidity however.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Tonight...VFR. BKN-OVC deck at 9000 feet will spread into the
region after midnight tonight. A few sprinkles or light rain
showers are possible, mainly at KABE/KRDG and possibly KILG.
LGT/VRB winds.
Friday...VFR. Sct-bkn aoa 6000 ft. Light northwest winds with
max gusts 15 kt. An afternoon wind shift to southeast is
possible at ACY.
Outlook...
Fri night thru Tuesday...A prolonged period of VFR conditions
expected with high pressure across the area. A few low clouds
near the shore possible Saturday. Winds mostly under 10 knots.
&&
.MARINE...
Winds and seas are expected to remain below small craft advisory
conditions through Friday.
Outlook...
Friday night through Sunday...Winds and seas below advisory
criteria. Fair weather.
Sunday night through Tuesday...SCA seas developing on the ocean
Sunday night and Monday then persisting into Tuesday. Sub-SCA
seas over Delaware Bay. Mostly fair weather expected.
Rip Currents...
There is a Low risk for the development of dangerous rip
currents at NJ and DE ocean beaches on Friday. However, with
late day sea breezes developing, the shift to a S to SE wind may
result in a localized moderate risk for the development of
dangerous rip currents, mainly at NJ ocean beaches late in the
day. Confidence is low at this time, so will keep the forecast
risk at Low.
Low does not mean NO risk! Please be smart selecting where you
swim. Safety requires a flotation device available nearby and
preferably swimming within sight of a lifeguard.
Also...not only are we hearing stories of bacteria here and
there along the NJ coast, but we were informed of a few Man O
War stings. So even in this outstanding weather pattern, follow
the advice of local officials regarding your swim zones.
IF anyone is seeking advice for choosing swim days along the NJ
and DE coasts...the next couple of days should be potentially
nicer versus next week (bacteria and Man o Wars issues excluded)
Next week, the swimming safety and comfort is expected to
diminish as noted below.
Early next week...the risk for the formation of dangerous rip
currents should increase to at least moderate. Atlantic waters
will become rough and more difficult to manage for swimmers
because of increasing easterly swells and persistent onshore
flow in association with the high re-centering to our north and
some sort of low pressure system moving northeast, off of the
southeast coast of the United States. The result, the building
of an 8 second easterly swell...possibly to 7 feet or so by
Monday or Tuesday, at least along the southern NJ and DE coasts.
&&
.CLIMATE...
Barring unforeseen rain, the period thru next Monday could
potentially be only our second rain-free stretch that spans at
least five days in what has otherwise been a very wet summer.
June 8-13, was the other 5+ day dry stretch this summer, was
technically not rain free as MPO reported 0.01 inches of rain
on both 10 June and 13 June.
The last time all eight of our climate sites have not recorded
any measurable rainfall for at least five consecutive days was
March 2-6, 2017 (honorable mentions: 15-19 May except for 0.02
inches at MPO on 15 May and the previously mentioned 8-13 June
period).
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...None.
NJ...None.
DE...None.
MD...None.
MARINE...None.
&&
$$
Synopsis...CMS
Near Term...Drag/MPS
Short Term...Drag
Long Term...O`Hara
Aviation...Drag/MPS/O`Hara
Marine...Drag/MPS/O`Hara
Climate...
Area Forecast Discussion
National Weather Service Pueblo CO
346 PM MDT Thu Aug 24 2017
.SHORT TERM...(This evening through Friday)
Issued at 346 PM MDT Thu Aug 24 2017
Upper wave pushing across CO today, with area of sct tsra moving
slowly eastward across the mountains at mid-afternoon. While
persistent high level cloud deck has limited instability somewhat
across the region, CAPE has still pushed into the 1000-1500 J/KG
range along and east of the mountains, with some briefly vigorous
updrafts noted on radar since 20z. Main limiting factor for storm
strength and coverage today and tonight is very weak wind shear,
with 0-6km values running 20kts or less across the region. Forecast
for the remainder of the afternoon and evening follows the HRRR and
NAM fairly closely, with sct storms pushing gradually eastward from
the mountains across the plains, before storms diminish toward KS
border by midnight. Suppose one or two storms could be briefly
strong, with heavy rain and small hail possible. Models not quite
as enthused about storms over the far eastern tier of counties as
runs earlier this morning, so will nudge pops downward along the KS
border somewhat for this evening. Skies clear overnight as wave
pushes east, leaving seasonably cool temps in its wake by early Fri
morning.
Expect a downturn in convection across the area Fri as air mass
dries slightly and weak subsidence develops across the region.
Mountains will still see isolated storms, but will keep most lower
elevations dry as convection stays close to the higher terrain. With
less cloud cover, max temps should creep upward a few degf,
especially along and east of the mountains.
.LONG TERM...(Friday night through next Thursday)
Issued at 346 PM MDT Thu Aug 24 2017
A relatively tranquil longer term forecast is in the offing(outside
of a later Sunday into Monday time-frame) in combination with
above average temperatures. Primary longer term meteorological
concerns for the forecast district continue to be temperatures
and pops.
Latest longer range forecast model soundings, computer
simulations and PV analysis still suggest that upper ridging
centered near the 4-Corners Saturday shifts over Nevada and Utah
from Sunday into Wednesday in advance of relocating to near the
4-Corners region again by next Thursday.
Also, varying degrees of eastern Colorado lee-side troughing is
still anticipated from Friday evening into Saturday night in
advance of a north-northeasterly surface surge moving across the
forecast district Sunday. Then, next round of eastern Colorado
lee-side surface troughing is projected to develop from later
Monday into next Thursday.
The combination of the relatively moist north-northeasterly
surface surge on Sunday in addition to passing upper
disturbances from later Sunday into Monday will allowed enhanced
precipitation chances over sections of the forecast district
during this time-frame, otherwise generally low-grade pops in
combination with above seasonal temperatures are anticipated
during the balance of the longer term over the majority of the
forecast district.
Also, latest temperature trends still continue to suggest that
minimum and maximum temperatures during the longer term should
generally run at or above late August climatological averages over
the forecast district with warmest conditions anticipated Saturday
and Wednesday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 346 PM MDT Thu Aug 24 2017
VFR conditions expected at COS, PUB and ALS terminals over the next
24 hours. Mountain convection will spread slowly eastward for the
remainder of the afternoon and into the evening, and will carry a
VCTS at all terminals from 21-22z through about 03Z this evening.
Brief MVFR conditions and small hail will be possible with stronger
storms along and east of I-25 into the evening. Storms gradually end
toward midnight, with clearing skies overnight. Much less in the way
of tsra over the region on Friday, and will likely keep convection
out of all tafs for Fri afternoon, with just a few mountain storms
expected.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
Area Forecast Discussion
National Weather Service Tucson AZ
858 PM MST Thu Aug 24 2017
.SYNOPSIS...A low grade monsoon pattern will prevail into the middle
of next week. Adequate moisture will produce isolated to scattered
mainly afternoon and evening thunderstorms, with the greatest
coverage east of Tucson. Daytime temperatures will be near or
slightly above seasonal normals.
&&
.DISCUSSION...We`ve dried out a bit over the past 24 hours, with
the 00Z KTWC sounding down to 1.2 inches, and satellite estimates
continuing that trend (suggesting values near or below 1 inch for
much of SE AZ). Surface dew points are down 5 to 10 degrees as
well (generally in the 50s outside of border areas). Deeper
moisture not far away in Sonora and Chihuahua, and we`ll see an
ebb and flow of moisture fluctuations over the next several days.
Likely low-grade monsoon thunderstorm coverage most days, favoring
mountains. Please see the previous discussion below for details.
&&
.AVIATION...Valid thru 26/06Z.
Clearing overnight. Some isolated storms possible on Friday
although they should favor the higher terrain areas. Otherwise,
VFR conditions with surface wind variable in direction, mainly
less than 12 kts. Aviation discussion not updated for TAF
amendments.
&&
.FIRE WEATHER...Isolated to scattered mainly afternoon and evening
thunderstorms will occur into next week. Thunderstorm coverage will
fluctuate daily but locales east of Tucson will generally be
favored. 20-foot winds will generally exhibit an easterly component
starting Friday, but will mainly remain below 15 mph.
&&
.PREV DISCUSSION...Latest runs of the HRRR as well as UA WRFs and
other convective allowing models suggest it should be a quiet
night across the lower elevations. Hard to argue against that
theory based on the flat cu visible on area webcams. Much of the
same is forecast on Friday as GFS/NAM/ECMWF all indicate slightly
drier air in the deserts as compared to today. With weak
anticyclonic flow forecast in the mid levels, even cu may struggle
to develop tomorrow afternoon west of Tucson. Mountain showers
and storms will once again be possible although nowhere near as
widespread as what was seen Wednesday.
Looking into the weekend and beyond reveals a large scale shift of
the mid level high to our north, with northeasterly flow forecast
across the area through the middle of next week. In theory this
pattern should be conducive for shower and storm development but BL
moisture isn`t nearly as high as it could be with mean mixing ratios
only forecast to reach 5-6 g/kg. Consequently afternoon MLCAPES are
only forecast to reach less than 500 J/kg. Granted this is still
several days away but it looks to be a relatively low grade
monsoon pattern all the way through the end of next week.
As for temps, look for at or slightly above normal readings every
day through the end of next week.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
Meyer/Leins
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