Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 07/22/18
AREA FORECAST DISCUSSION
National Weather Service Eureka CA
253 PM PDT Sat Jul 21 2018
.SYNOPSIS...Temperatures will not be quite so hot across the
interior valleys this weekend, before returning closer to 100
degrees for the upcoming week. Cooler weather with areas of marine
stratus will be found along the coast, especially south of Cape
Mendocino. Isolated thunderstorms will impact areas around
Trinity County on Sunday.
.DISCUSSION...Heat and thunderstorm activity over the interior along
with areas of smoke, haze and coastal stratus will continue to be
the forecast challenges...none of which are terribly out of the
ordinary for northwest California in late July. Approaching 2 pm
PDT, a look at the visible satellite reveals mostly clear skies
across the bulk of the interior, with smoke and haze across Del Norte
and mainly northwest portions of Humboldt County. Webcams along
the Redwood coast show mainly clear but hazy skies. Coastal
stratus has been persistent along the vast majority of the coast
near and south of Cape Mendocino thus far today. Light winds there
are tending southerly and onshore, with a coastal eddy
circulating a continued supply of stratus up from offshore of
Point Arena. These coastal clouds and fog may keep the Mendocino
coast cloudy for much of the next couple of days, and will try to
begin to peel around Cape Mendocino into Humboldt Bay tonight.
Expect with northerly winds still offshore and adjacent to the
north side of Cape Mendocino, the bulk of the stratus shield may
struggle to make headway. Still think there will be a bit more
cloudiness along the Humboldt coast later tonight into Sunday
morning, perhaps filling in and thickening along the entire
Redwood coast by Sunday night.
Meanwhile, the switch to more southerly low-level flow, albeit
still very light, should tend to shift some of the smoke out of
our area, as indicated by the HRRR model. However, expect areas
closest to the Nachez fire around Del Norte county to remain hazy
tomorrow. Otherwise, the focus will shift to a threat of
thunderstorms over eastern and northeastern Trinity County on
Sunday afternoon. The models have generally seemed a little bit
too aggressive with mid-level moisture and instability thus far,
though there is some sign of that in ACCAS to our southeast, as
close as Napa county. Models indicate much more in the way of
instability and anomalous precipitable water values tomorrow as
this mid-level monsoonal moisture settles in across our area.
However, mid-level lapse rates look fairly poor, with limited
shear and forcing under a strong mid/upper-level ridge of high
pressure. The consensus of guidance points toward a couple storms
firing up around the Trinity Alps or perhaps Trinity Center, but
for the above reasons, am doubting the storms get very strong or
are more than isolated coverage-wise. Better chances will exist
out of our area, into Siskiyou county.
Heat will continue to be an ongoing concern for the interior,
though this weekend is giving us a relative break, with just mid
80s to mid 90s for most. High pressure ridging over the
southwestern United States will build through the middle of the
upcoming week, with the hottest interior valleys 100-105 by
Wednesday. There are few signs of any real relief in this hot
pattern for the foreseeable future.
.AVIATION...All terminals have been experiencing VFR conditions
early this afternoon. Smoke from the wildfires to the north continue
to produce a broken to overcast layer at around 4000 ft with slight
visibility reductions at the surface as well. HRRR smoke guidance
indicates smoke should remain entrenched across interior Del Norte
County this evening and through tomorrow however smoke impacts at
ACV may begin to lessen. The other forecast concern is the
persistent stratus that has remained south of Cape Mendocino so far
today. Model guidance has been struggling with the stratus which
places low confidence in their solutions for tonight and tomorrow
morning. However, northerly winds continue to decrease as we go
through the afternoon which should allow stratus to begin to round
the cape late this afternoon or evening. Southerly winds are
expected to strengthen along the entire coast by tomorrow morning
which means that low clouds and reduced visibilities can be expected
at ACV and CEC at the latest by late tomorrow morning. Clear skies
will continue to prevail at UKI during this cycle. Cumulus clouds
will be on the increase along the interior mountains this afternoon
which may increase turbulence. /WCI
.MARINE...The surface thermal trough will continue to pivot across
the Southern waters. As a result, northerly winds will continue to
decrease as we go through the afternoon and into the evening. Winds
will remain elevated across the northern outer waters where gale
gusts will remain possible through this evening. Near the coast,
southerly winds will begin to strengthen late tonight and into
tomorrow morning to around 5 to 15 kts. Seas across the outer waters
and northern inner waters will remain steep and hazardous through
Sunday afternoon. Northerly winds will begin to increase again by
the middle of next week. /WCI
.FIRE WEATHER...There may still be a small area of northeast Del
Norte county with enhanced northeast winds tonight, but overall
trends will be better, with lighter winds, and higher RH values.
Temperatures will continue to be hot through the upcoming week,
albiet a little bit of repreive for today and Sunday from the
above 100-degree readings.
Isolated thunderstorms will be an issue around northeastern
Trinity County on Sunday, but do not expect abundant lightning at
this time, with more concerns in that department farther north and
northeast into Siskiyou county. Thus have held off on any Red Flag
Warnings, but will continue to highlight isolated lightning in the
FWF. See the above discussion section fore some more forecast
reasoning. Might not be able to completely rule out a stray shower
or weak storm around the Trinity Alps Monday or Tuesday afternoon,
but otherwise it looks like the week ahead will be mostly storm-
NORTHWEST CALIFORNIA COASTAL WATERS...Small Craft Advisory until
3 AM PDT Sunday for PZZ450.
Gale Warning until 9 PM PDT this evening for PZZ470.
Small Craft Advisory until 3 PM PDT Sunday for PZZ475.
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Area Forecast Discussion
National Weather Service Glasgow MT
916 PM MDT Sat Jul 21 2018
Showers and storms have been ongoing this evening in central MT
and are beginning to move into our western zones. HRRR, HiRES NMM,
and RAP all pick up on this rainfall and thunder (so do the GFS &
Euro to some extent), so made adjustments accordingly to bring
rain and thunder through the CWA overnight tonight. By tomorrow
afternoon, it should be a sunny, dry, and breezy day across the
Most of the forecast challenges and focus remained on the ongoing
severe thunderstorms pummeling our Daniels, Sheridan, and
Roosevelt Counties this afternoon and evening. Tried to blend
current conditions with the best model data consensus. Large hail,
and frequent lightning seem to be the predominant threats.
Those severe thunderstorms will diminish and move east into North
Dakota later tonight. The frontal system responsible for this
series of supercells is drawing in hot moist air from the
southeast ahead of the front with cooler, drier are coming in
behind the front from the west and northwest later overnight and
through all day Sunday. Those winds on Sunday will be strong
enough to justify having issued another Lake Wind Advisory through
all day Sunday.
Overall forecast thereafter will follow a drier and cooler
pattern with high temperatures barely reaching into the 80s. The
upper level low pressure system responsible for this cooler
weather pattern will keep the hot high pressure from the south
dampened down through all of next week.
A return to hotter temperatures may be possible as the western
states high pressure ridge rebounds through next weekend.
Flight Category: VFR, but some visibility reduction is possible
near active rain showers and thunderstorms through the morning
Synopsis: Showers and some thunderstorms will move across the
region overnight tonight, moving east of the forecast area by
Winds: Should be out of the northwest on Sunday between 15 to 25
kts with higher gusts at times.
A few showers and thunderstorms are possible in the west overnight
tonight into Sunday morning, spreading east in the morning and out
of the area by the afternoon.
Outflow boundaries from Saturday afternoon storms will complicate
wind forecasts for overnight tonight in the west. Winds from the
ENE have been reported behind the storms, which should subside
A strong and gusty northwest wind will set in the re-enforcing
air mass behind the cold front on Sunday. Expect sustained winds
of 20-25 mph and some gusts up to 35 mph. This would blow any
remaining fires back toward the already burned area and into the
U-L bend of the lake. Avery
Lake Wind Advisory from 2 AM to 8 PM MDT Sunday For Fort Peck
Lake for Central and Southeast Phillips...Central and Southern
Area Forecast Discussion
National Weather Service Grand Junction CO
547 PM MDT Sat Jul 21 2018
.SHORT TERM...(Tonight through Sunday night)
Issued at 348 PM MDT Sat Jul 21 2018
Temperatures are climbing a few degrees more today compared to
yesterday with less cloud cover over the region. Lingering
moisture and daytime heating are triggering scattered showers and
thunderstorms this afternoon across the area, favoring the
western Colorado mountains, but these storms will diminish by
midnight with the loss of the daytime heating. The HRRR and NAM
are showing increased shower activity over the Eastern Uintas
beginning tomorrow morning as a short wave begins to cross through
the region. Again, the higher terrain across western Colorado
will see increased shower activity tomorrow afternoon, although
the showers will be more widespread due to the instability
introduced with the disturbance passing to the north. Expect a
brief break during the overnight hours on Sunday night with
slightly cooler lows as heavier cloud cover dissipates.
.LONG TERM...(Monday through Saturday)
Issued at 348 PM MDT Sat Jul 21 2018
Things begin to become a little more interesting as we head into
the new work week. As has been the trend over the last several
model runs the area of high pressure is expected to retrograde
back into the Four Corners area by late Monday. As this occurs
another embedded shortwave will drag across the Continental
Divide on Monday, resulting in an uptick in shower and
thunderstorm coverage throughout the day. WPC has issued a slight
risk for excessive rainfall along this area as precipitable water
values once again climb with the passage of the disturbance. If
models continue to trend this way Flash Flood Watches may have to
be considered for the major burn scars in our forecast area.
By daybreak Tuesday the center of the high will be positioned over
the northern Arizona/New Mexico border. Drier air will work into
the region from the northwest by midweek as the high reaches
SoCal. However, moisture will continue to be recycled under the
high through the end of the week as daytime heating helps fuel at
least isolated orographic convection each day. Temperatures will
gradually warm through the long term period as the high builds
back over the southwestern CONUS.
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 547 PM MDT Sat Jul 21 2018
Expect thunderstorms in the vicinity of KTEX through 02Z with a
brief light showers possible along with outflow winds to 25 MPH.
Scattered showers and a few embedded thunderstorms will continue
across the region this evening, however, with the exception of
KTEX, the remaining TAF sites are unlikely to experience this
activity directly this evening through midday Sunday.
Thunderstorms will bubble up again Sunday afternoon, mainly over
higher terrain. Outflow winds could affect TAF sites, however
shower/thunderstorm activity are unlikely to impact airfields.
Despite moist convective activity, TAF sites can anticipate VFR
conditions through the next 24 hours.
Area Forecast Discussion
National Weather Service Goodland KS
538 PM MDT Sat Jul 21 2018
.SHORT TERM...(This afternoon through Monday night)
Issued at 115 PM MDT Sat Jul 21 2018
Overview: The Tri-State area will be situated on the N/NE
periphery of an upper level ridge (centered over New Mexico), at
the southern fringe of NW flow aloft.
Today-Tonight: Small amplitude perturbations on/near the
tropopause (150-175 mb level) will round the northern periphery
of the ridge from the Desert SW/4-Corners region into portions of
the Rockies and High Plains this afternoon into tonight. Such
subtle/high-altitude features are incredibly difficult to
anticipate/track and their `depth of influence` varies depending
on the thermodynamic profile -- the more unstable, the greater
the influence. Low-level forcing will be confined to shallow
convergence invof a weak SFC-H85 trough in the lee of the Rockies
and perhaps weak orographic ascent associated with ESE/SE low-
level flow. Recent runs of the HRRR and NAM NEST suggest that
scattered convection will develop over the mountains/foothills of
CO/WY this afternoon with activity gradually growing upscale and
propagating E/SE across the Tri-State area this evening (between
01-07Z). Effective deep-layer shear on the order of 25-30 knots
and moderate MLCAPE (1000-1500 J/kg) suggest organization will be
multicellular in nature. With steep mid-level lapse rates (8C/km)
and strong DCAPE, damaging winds /occasional severe downbursts/
will certainly be possible. A broader swath of damaging winds
cannot be ruled out given sufficient upscale growth /cold pool
consolidation/, particularly in northeast CO where diurnal timing
will be more favorable. Expect convection to wane after midnight.
Sun-Sun night: With little change in the synoptic pattern, expect
conditions to be similar to those today/tonight.
Mon-Mon night: Relatively little change in the synoptic pattern
compared to today and Sunday. However, with ongoing convection
possible over and upstream of the Tri-State area Sunday night into
Monday morning, forecast confidence decreases significantly.
.LONG TERM...(Tuesday through Saturday)
Issued at 128 PM MDT Sat Jul 21 2018
An area of upper high pressure remains over the southwestern CONUS
on Tuesday, with ridging across the west and a trough over the
eastern portion of the country. This results in northwesterly flow
aloft for the region. A closed low advances through Canada midweek
and continues north of the Great Lakes region. As the low progresses
east, the upper high weakens and retrogrades, centering near
Arizona by Saturday.
While this pattern unfolds, multiple disturbances travel through the
northwest flow with a surface cold front lingering nearby,
generating chances for showers and thunderstorms each day during the
long term period. Widespread severe weather is not anticipated at
this time. However, cannot rule out a few severe thunderstorms
during this timeframe with increased shear in place and adequate
instability. Good moisture and PWATs of 1 to 1.5 inches also suggest
that there is the potential for locally heavy rainfall and flash
flooding. Will continue to monitor and pin down details as guidance
comes into better agreement in the coming days.
Highs are in the 80s throughout the period, excluding Wednesday when
temperatures reach the low 90s south of Interstate 70. Low
temperatures remain in the upper 50s to low 60s.
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 533 PM MDT Sat Jul 21 2018
VFR conditions are expected through the 00Z TAF period at GLD and
MCK. Mostly high clouds with light southeast winds are expected at
both locations after sunset. TS is possible in the vicinity of
GLD between 04-08Z as storms move out of far eastern Colorado and
into northwest Kansas. Storms will diminish through the evening as
they continue east with TS in the vicinity of MCK between 05-07Z.
Area Forecast Discussion
National Weather Service Wilmington NC
831 PM EDT Sat Jul 21 2018
Low pressure developing to our west should bring showers and
thunderstorms back into the area tonight and Sunday. Next week
is shaping up to be very unsettled as low pressure remains
across the Southeast and tropical moisture spreads onshore.
.NEAR TERM /THROUGH SUNDAY/...
As of 800 PM Saturday...A few light late afternoon/early evening
showers popped up along the northern tier of the CWA in an area
of surface convergence. This convergence zone will move off to
the northeast, and am not expecting any additional convective
development until an upstream shortwave crosses the area after
midnight. By then, showers and thunderstorms associated with the
shortwave will be approaching the Pee Dee region. Although the
atmosphere will be stabilizing, it should remain unstable
enough to support the potential for weakening convection to
make it to the Cape Fear coast by 10-11Z. South of a Wilmington
to Florence line, dynamic support will be very weak, and
overnight activity may remain somewhat isolated.
On Sunday the models are showing drier precipitable of 1.5 inches
and as this afternoon the temperatures aloft are cooling to -8
to -10. So will continue with a chance of convection on Sunday.
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 300 PM Saturday...Cyclonic flow through most the entire column
through the period-certainly not the norm for July. With the center
of this deep layer gyre remaining to our west the coastal Carolinas
will be in deep layer southerly moist flow. And while these
conditions certainly do favor widespread cloud cover and the ever-
present chance for rain the axis of deep moisture and specter of
heavy rain likely remain just off the coast. Should the mid level
trough axis move even slightly westward in future model runs then
the coast may once again be under the gun for appreciable rainfall.
There is another possibility that some higher QPF could rotate into
the area late Monday night. Should the upper low cut off enough from
the northern branch trough then deep layer flow could back from S to
SSE or SE and fling higher PW into mainly areas-NC moreso than SC.
Cloud cover will keep Monday highs below climatology while holding
both nights above.
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 300 PM Saturday...Not a lot of change to the extended forecast
and really much wasn`t expected as the guidance has been
relatively stable for several cycles now. Mid level low pressure
is still expected to linger in the Southeast for a few days
with a deep tropical plume/connection funneling into the
Carolinas. The GFS appears to open up the low a little quicker
Thursday (and the latest ECMWF even moreso) with more of a
typical southwest flow aloft, Piedmont Surface Trough setup late
Thursday through Saturday. I have increased the pops for
Tuesday into early Wednesday to mostly categorical with likely
values into Thursday with high chance for the remainder of the
period. Temperature forecast remains relatively unchanged with
highs in the upper 80s to near 90 trending slightly higher in
time with a little less moisture. Overnight lows very stable in
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 00Z...Lots of uncertainty with respect to convection
overnight. The HRRR model has been all over the place and cannot
seem to nail down the timing and the severity of the convection.
Safe to say there will be some storms after midnight, but may be
only isolated. Sunday, upper low will be spinning basically in place
to our west, with a dry slot over our CWA. Convection will be
isolated in the afternoon, possibly focused on the resultant
boundary. Moderate southerly flow is forecast.
Extended Outlook...Occasional MVFR to IFR conditions due to
scattered SHRA and TSRA through Thursday.
NEAR TERM /THROUGH SUNDAY/...
As of 800 PM Saturday...Winds across the waters are generally
southwest this evening as a result of a trough of low pressure
extending from Norfolk to Fayetteville. THe orientation of the
trough won`t change much overnight, and will allow south to southwest
winds on the order of 15 knots to continue, with seas running
around 4 feet. The winds are expected to become more southerly
on Sunday, and the southerly fetch will maintain 3 to 5 ft seas.
SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 300 PM Saturday...A Small Craft Advisory will be in effect
for the period for NC zones-the headline may not materialize
until daytime Monday for SC zones. Low pressure at all levels of
the troposphere will be found to our west, which is very
uncommon for summertime. Southerly flow will strengthen over the
short term and should reach advisory levels as will seas-both
seeing a relative delay across southern waters vs. northern
LONG TERM /TUESDAY THROUGH THURSDAY/...
As of 300 PM Saturday...Southeast winds of 15-20 knots will be in place
much of Tuesday into Wednesday. Winds will veer to more
south/southwest for the remainder of the period with decent speeds
continuing. Elevated seas near Small Craft Advisory criteria will be
side by side with the winds with slightly higher values early in the
As of 330 AM Saturday...Recent heavy rainfall in Wilmington is
pushing our 2018 rainfall into record territory. Keep in mind
our May rainfall total of 14.36 inches exceeded the next wettest
May by over five inches, and January and June totals were also
well above normal. The increasing likelihood for an El Nino
winter could help make 2018 one of the wettest years ever seen
in the Port City.
Wettest years in Wilmington`s history, Jan 1 through July 20...
#1 48.11 in 2018
#2 45.47 in 1886
#3 44.13 in 1966
#4 39.72 in 1973
#5 38.40 in 1998
SC...Beach Hazards Statement from 8 AM EDT Sunday through Sunday
evening for SCZ054-056.
NC...Beach Hazards Statement from 8 AM EDT Sunday through Sunday
evening for NCZ106-108.
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1007 PM EDT Sat Jul 21 2018
Low pressure will move north of the area this evening and tonight. A
warm and moist southerly flow between low pressure to the west and
high pressure over the Atlantic will produce above normal chances for
showers and thunderstorms through midweek as a weak front lingers along
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
As of 1005 pm Saturday...Scattered convection approaching from
the west. Kept slight chance in the northeast counties with
chance elsewhere. No change to overnight lows.
Prev disc...Differences exist later tonight amongst the HRRR,
NSSL- WRF and 3km NAM with regards to precipitation development
as the NSSL- WRF shows a band of convection moving through the
region closer to midnight, while the HRRR and NAM12 show any
activity holding off until early Sunday morning. Likely trigger
will be a shortwave crossing Kentucky that has become
convectively active over the past hour or so. Given the
uncertainty in the precipitation timing, have lowered PoPs from
likely to high chance from after 03z through the overnight
hours. With a record-breaking precipitable water of 2.46 inches
from this morning`s 12Z MHX sounding, any convection has the
potential to quickly produce heavy rainfall and localized
flooding. Low temperatures tonight should be in the low to mid
.SHORT TERM /6 AM SUNDAY MORNING THROUGH 6 PM SUNDAY/...
As of 350 PM Saturday...After any initial precipitation in the
morning, Sunday afternoon again looks convectively active with
deep southerly flow around high pressure offshore with surface
trough lingering inland over the Piedmont of North Carolina with
mid-level low parked over the Southeastern United States.
Following the trends from both the GFS/ECMWF, PoPs go from high
chance during the morning to likely during the afternoon. With
high precipitable water values, heavy downpours are possible and
eastern NC is in a "Marginal" threat of excessive rainfall for
Sunday. The deep moisture and widespread cloudiness should
reduce the threat for any severe convection Sunday. High
temperatures will reach the mid to upper 80s Sunday.
.LONG TERM /SUNDAY NIGHT THROUGH SATURDAY/...
As of 315 AM Saturday...A warm and moist southerly flow will
continue Sunday Night through next week due to low pressure to
the west and high pressure over the western Atlantic Ocean,
leading to unsettled weather conditions from through much of
Sunday Night through Wednesday...Deep, warm, and moist
southerly flow will continue behind a departing low pressure
system Sunday night and will persist through much of the
upcoming week between broad low pressure aloft to the west and
western Atlantic high pressure. This pattern is conducive for
widespread showers and thunderstorms, most widespread during
peak heating with a persistent mid level trough over the eastern
US. Timing for the highest chances of rain is roughly Monday
afternoon through Wednesday when channeled vorticity sets up
over Eastern NC with an elongated axis of very high PWATs
stretching from the tropical western Atlantic Ocean. Given
persistence amongst guidance over the past several runs, have
increased PoPs slightly during this time frame, with the
potential for 2 to 6 inches of rainfall, highest closer to the
coast. Will continue to highlight severe/flood potential in HWO.
Thursday and Friday...The persistent upper trough to our west
finally fills and shifts northeast from the Deep South states
towards the Mid-Atlantic, with high pressure continuing
offshore. Moist southwesterly flow will be present both days
with convection more diurnally focused.
Temps Sunday Night through Friday will be close to
climatological normals, ranging from highs in the upper 80s
inland to mid 80s for the coast. Minimum temps will range from
the low to mid 70s.
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Short Term /through 18Z Sunday/...
As of 635 pm Saturday...All 4 terminals are VFR at present.
However, scattered thunderstorms over the western part of the
state are moving east and will likely impact the sites later
this evening. Sub-VFR expected in scattered storms overnight,
and in numerous storms during the day Sunday. Surface winds will
be mainly south less than 10 knots.
Long Term /Sunday Night through Thursday/...
As of 330 AM Saturday...Periodic Sub-VFR conditions are
expected through Wednesday as an unsettled pattern develops
across Eastern NC. Southerly flow will continue Sunday night and
will last through next week.
Short Term /Tonight and Sunday/...
As of 1005 pm Saturday...Current marine zones still look good.
No changes needed late this evening. Gusty southwest winds will
continue overnight with rough seas persisting through the
evening before subsiding somewhat after midnight. While
conditions may subside for several hours late tonight and early
Sunday, have extended the Small Craft Advisory from tonight
through later this week, and wind and seas quickly increase
again by late morning to midday on Sunday. With high pressure
offshore and a surface trough over the Piedmont of North
Carolina remaining in place for much of the next several days,
gusty southerly winds and rough seas will continue. Did extend
the SCA for the Pamlico Sound until 5 AM Sunday morning, but
conditions there should subside below SCA status for at least a
day or so.
Long Term /Sunday Night through Thursday/...
As of 330 AM Saturday...Low end SCA conditions are expected
over the waters for much of the period. Sunday Night through
Wednesday, moderate S/SW winds 10-20 kt develop between low
pressure well west of the waters and high pressure across the
western Atlantic Ocean, producing 4 to 6 ft seas, highest for
the outer fringes of the coastal waters. While boating
conditions will be poor for most of the period, conditions will
be exacerbated by a prolonged period of showers and
thunderstorms from approximately Monday afternoon through
MARINE...Small Craft Advisory until 6 AM EDT Sunday for AMZ135.
Small Craft Advisory until 9 PM EDT Thursday for AMZ150-152-
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1101 PM CDT Sat Jul 21 2018
.SHORT TERM...(This evening through Sunday)
Issued at 345 PM CDT Sat Jul 21 2018
This afternoon, the Upper Midwest was caught between an anomalous
upper low across the Great Lakes-Ohio Valley, and an upper ridge
over the high plains of Montana and western North Dakota. Deep
layer moisture has been abundant in the eastern 1/4 of MPX
forecast area of west central Wisconsin due to the persistent
wrap around of the moisture associated with the upper low. Mid
level lapse rates are weak in this area of west central Wisconsin,
but at least enough to generate a few diurnally driven showers or
storms through the early evening. Elsewhere over the Upper
Midwest, very dry mid levels will keep this area dry through
The persistent north/northeast flow in the boundary layer will also
lead to an increase in boundary layer moisture across Wisconsin
later tonight. This may lead to low stratus/fog building across the
area toward sunrise. Sunday will mostly sunny and dry with an
increasing southeast wind in western Minnesota in advance of a cold
front moving across the Dakotas.
.LONG TERM...(Sunday night through Saturday)
Issued at 345 PM CDT Sat Jul 21 2018
The pattern will be characterized by an upper high in the
southwest that slowly retrogrades, leading to a broad upper low
and trough across central and eastern Canada and into the U.S. by
mid and late week.
Aforementioned ridge over the high plains will shift eastward, and
it should extend across Minnesota tomorrow evening. An upper low
in western Canada will follow, bringing broad ascent later Sunday
night and Monday in the wake of the ridge. Moisture will be
abundant, evidenced by the storms developing at this time from
Saskatchewan into Wyoming and Colorado. Thus have maintained the
chance of storms late Sunday night and Monday across the area.
Models are in decent agreement with moving the trough past MN/WI
later Monday, so Monday night and Tuesday should be dry.
As the Canadian upper low heads for the Great Lakes region
Thursday, the next trough will approach Tuesday evening. Cooler
air will begin filtering in with northwest flow. Temps aloft drop
quite a bit, and this is a pattern typical of scattered showers
with a few afternoon/evening thunderstorms as well. Highs
Thursday look to be the coolest of the upcoming period, when the
upper low is the closest to MN/WI. But even as it moves away into
eastern Canada Friday, there should still be some northwest flow
and cool enough temps aloft to help promote more showers on Friday
afternoon/evening. And again on Saturday. Certainly a pre-fall
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1101 PM CDT Sat Jul 21 2018
Main change from 00z TAFs is stratus in WI is not looking to make
it as far west in WI, which means EAU will remain in the clear. It
will be VFR through the night, with only a small threat of br/fg
at AXN/STC/RWF, but potential is too low to include in the TAFs.
With high pressure passing off to the north Sunday, we`ll have
light east winds and a few-sct cu field between 3k and 5k feet.
During the afternoon, thunderstorms will develop along a cold
front in NODAK and will be heading toward AXN by the end of the
TAF period. A few of the CAMs show TS reaching AXN as early as 3z,
but that thunder will be on a decreasing trend, so will wait until
confidence increases on TS evolution into MN before brining any
mention in to the TAF.
KMSP...At the end of the period, a few of the CAMs are indicating
showers may be in the area, with the HRRR being the most
aggressive with showing showers in the area as early as 8z. This
looks overdone when looking at forcing/instability forecasts, so
have kept MSP dry and would be surprised if MSP saw anything at
all with this front coming through on Monday.
/OUTLOOK FOR KMSP/
Mon...VFR. Slight Chc -TSRA. Wind vrbl bcmg NW 5-10 kts.
Tue...VFR. Wind W 5 kts.
Wed...VFR. Slight Chc -TSRA. Wind W bcmg NW 10G20 kts.
Area Forecast Discussion
National Weather Service New York NY
1057 PM EDT Sat Jul 21 2018
A potent storm will move up the coast and impact the area,
especially late tonight as the associated low pressure center
passes to the west. A frontal boundary will remain west of the
region through much of the week, with an extended period of
unsettled weather with the chance of showers and thunderstorms
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Forecast on track this evening with just a few minor adjustments
to reflect latest observations. Otherwise, warm core non-
tropical low was moving along the Delmarva coast at 01Z. Bands
of convection were moving into the northern NJ coast and south
of Long Island, some of the cells had very weak rotation, along
with some higher wind gusts.
Latest HRRR brings a strong wind core with gusts 50-60 kt up to
the south shore of NYC and Nassau. So a wind advy continues
for western coastal sections for tonight based on that
guidance, along with GFS LAMP guidance forecasting advy criteria
sustained winds to 30 kt at Bridgeport CT, and close to advy
criteria at KJFK. If latest runs of HRRR are correct there is
still a chance that the advy for the south shore harbor and
ocean locations may have to be upgraded to a high wind warning,
especially if winds take on a more SE vs E component.
Next concern is rainfall. Operational ECMWF/HRRR have been
forecasting heavy rain bands capable of producing a quick 2-3
inches of rain either just west of or straddling our NE NJ
counties, also additional similar rain bands run through parts
of western Long Island, the lower Hudson Valley, and SW CT. Have
higher confidence in the location of the westernmost band but
not those farther east, and since their coverage is not
widespread and HREF probabilities of 2+ inches of rain was
greatest just west of our area, opted against issuing a flash
flood watch. Depending on where these bands set up, will most
likely have to issue minor flood advisories, but will still have
to watch NYC closely for greater impacts to urban
infrastructure and possible flash flood warnings to address any
direct impact of that magnitude.
As these rain bands ride up into Long Island and southern CT,
combo of strong 0-1 km shear/SRH and sfc-based instability with
SBCAPE approaching 1000 J/kg may be enough to help produce low-
topped tstms capable of producing localized damaging winds or
a brief tornado.
A high rip current risk continues for the ocean waters.
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
By daybreak on Sunday, the heaviest rain should lift mainly
into eastern CT/Long Island. As tropical moisture continues to
stream northward, chances for showers and isolated thunderstorms
increase into the afternoon and at night.
Temperatures will be near normal or a few degrees below average.
A high risk of rip currents is expected for Sunday.
.LONG TERM /MONDAY THROUGH SATURDAY/...
Unsettled weather expected for the much of the long term period.
An upper level trough and surface front remain nearly stalled west
of the CWA as an Atlantic ridge remains offshore.
Periods of showers and thunderstorms will remain likely through at
least the first part of Monday night, especially west of NYC. POPs
then lower on Tuesday and Tuesday night as the upper ridge pushes
back to the west. There does remain some uncertainty with this
feature and kept probabilities across the eastern zones slight
chance and kept chance probabilities to the west of NYC.
An upper level low moving across central Canada on Wednesday slides
into the Great Lakes region by Thursday night. This will push the
trough and front closer to the region, with POPs increasing once
again through this period. Its nearly impossible this far out to
time any showers and/or thunderstorms and will keep at least some
50% chance POPs in the forecast. The trough and front cross the
region during the Thursday night/Friday morning timeframe with drier
weather expected for Friday. There may still be some lingering
precipitation, so will continue to maintain some low chance POPs.
A tropical like airmass will remain in place next week with highs
each day in the 80s and lows mostly lower to mid 70s. Humidity
levels remain uncomfortable with dew points in the lower to mid 70s.
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Low pressure over eastern Maryland at 02Z was beginning to track
just to the west of north and will continue to move to the
northwest overnight, moving to the west of the area terminals.
A warm front moves into the terminals late in the overnight and
lifts to the north Sunday. During Sunday the low weakens and
tracks into the eastern Great Lakes region.
Easterly winds and gusts will increase, with sustained to
around 20 KT, and occasionally as high as 25 KT, with gusts
increasing up to 35 KT. The highest winds and gusts are
expected to the at the coast terminals, especially KJFK and KISP
Ceilings have lowered to IFR and MVFR and will remain IFR
overnight. Visibilities will also lower to IFR especially in
moderate to heavy rain and isolated thunderstorms, as the warm
front draws closer to the region. So will continue with the
tempo from 04Z to 10Z.
LLWS wind shear is likely overnight with a E to SE low-level
jet, strongest at the coastal terminals.
By Sunday morning, south/southeast winds prevail, with gusts at
times in the 20 to 30 kt range. MVFR ceilings are likely, with
scattered showers expected through the end of the forecast
period, 00Z Monday. There may be a brief period of VFR
conditions, especially in the afternoon.
.OUTLOOK FOR 00Z MONDAY THROUGH THURSDAY...
.Sunday night...Mostly MVFR with a chance of IFR in SHRA and
.Monday-Thursday...MVFR/VFR with periods of SHRA and a chance
of TSTMs. S gusts 20-25 kt.
Gale warning remains up for all waters tonight as the coastal
storm works its way up the coast, with sustained winds 25-35 kt
and gusts 35-45 kt expected. There is a chance that winds on the
western ocean waters and New York Harbor may be quite a bit
stronger than this, and that this warning may have to be
upgraded to a storm warning. Will be watching coastal obs
along/off the Delmarva and Jersey shore for guidance on this
Gales should subside Sunday morning as a strong southerly LLJ
shifts east of those waters, with elevated seas continuing.
Winds will remain below SCA levels on the forecast waters
Sunday night through Wednesday. However, with a prolonged
southerly flow and southerly swells, ocean seas will remain at
SCA levels through Tuesday. Seas may briefly fall below 5 ft
Tuesday night into Wednesday, but SCA seas then return for
Wednesday night and Thursday.
Rainfall of 1-2 inches is likely in most areas from late tonight
into Sunday morning. Locally higher amounts are possible,
especially in any heavier or more persistent rain bands. Minor
urban and poor drainage flooding looks to be the main threat.
A flash flood threat does exist, but not at high enough
probability to warrant issuance of flash flood watches. This may
change as the coastal storm works its way closer to the area and
radar obs lend confidence on exact location of heavier rain
A prolonged period of unsettled weather is expected through the
upcoming week, with the chance of showers and thunderstorms
each day. The focus of higher rainfall amounts are expected
along a frontal boundary setting up inland.
While astronomical tides remain low with the full moon still a
week off, strong E-SE winds should result in surge of 2-3 feet,
high enough to yield brief minor coastal flooding in some
locations in/around the NY Bight, including the south shore of
Staten Island and the back bays of southern NYC and southern
Nassau. The south shore of Staten Island may be more susceptible
to flooding as strong E winds and shape of the coastline pile up
water in Raritan Bay. A coastal flood statement has been issued
for the overnight/early Sunday morning high tide cycle along the
south shore from NYC to southern Nassau county.
NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off
the air for an extended period of time.
CT...Wind Advisory until 6 AM EDT Sunday for CTZ009.
NY...Wind Advisory until 6 AM EDT Sunday for NYZ072>075-080-176-178-
Wind Advisory until 6 AM EDT Sunday for NYZ071-078-177.
High Rip Current Risk from 6 AM EDT Sunday through Sunday
evening for NYZ075-080-081-178-179.
NJ...Wind Advisory until 6 AM EDT Sunday for NJZ006.
MARINE...Gale Warning until 6 AM EDT Sunday for ANZ330-335-338-340-345-
Area Forecast Discussion
National Weather Service Portland OR
258 PM PDT Sat Jul 21 2018
.SYNOPSIS...An upper level trough will move east of the area this
evening. In it`s wake, high pressure aloft will expand northward
from the Great Basin over the next several days. This coupled with
a thermal trough at the surface will bring several days of very warm
temperatures at all inland locations. The coastal region will be
cooler with near seasonable temperatures.
.SHORT TERM...Tonight through Tuesday. Satellite imagery this
afternoon shows clear and sunny weather over the region. The main
message for the next several days is hot weather expected over the
inland areas. The coast will be the place to be to stay out of the
heat with seasonal temperatures of 60s to low 70s.
Temperatures will begin to climb on Sunday with valley high
temperatures in the low 90s. Inland high temperatures on Monday will
increase 5 degrees above Sunday`s readings with upper 90s expected
both Monday and Tuesday. We should see some overnight relief on
Sunday night as lows dip into the 50s Monday morning. However, there
will not be much relief Monday night as overnight lows will only
drop into the 60s around sunrise Tuesday morning. With very warm
temperatures expected Monday and Tuesday, we opted to issue an
Excessive Heat Watch for Mon and Tues. It`s worth noting that 90
degree temperatures over the inland area swill be with us most of
the week, which is 8 to 10 degrees above normal.
The other item to note is the possibility of some transport of smoke
from the wildfires in southwest Oregon into the Lane County Cascades
and foothills Sunday afternoon and evening. The HRRR smoke model
indicates some transport of smoke Sunday afternoon as the steering
flow becomes southerly. /tw
.LONG TERM...Tuesday night through Saturday...Warm, dry weather
continues through the week. Inland temperatures near 90 will be
common through the week, while the coast remains pleasant in the 60s
and 70s. A little relief from the heat is possible toward the end of
the week as a weak trough clips the area from the north. /tw
.AVIATION...A low level northwesterly flow pattern under building
upper level high pressure tonight and Sunday will lead to primarily
VFR conditions areawide through 00z Monday. The main exception to
this will be along the coast where there is a chance LIFR/IFR
conditions could briefly develop along portions of the coastline
between ~09-15z Sunday, but suspect most of the coast will remain
VFR given NE winds at 925 & 975mb should keep marine clouds and
fog offshore during this time.
KPDX AND APPROACHES...A northwesterly low level flow pattern
under building high pressure aloft will lead to primarily VFR
conditions through 00z Monday. /Neuman
.MARINE...High pressure over the northeast Pacific and thermal low
pressure over southwestern Oregon will result in a fairly typical
summer-time northerly wind pattern for much of the next week. Expect
wind gusts of 25 kt across the central Oregon waters through tonight
across the inner waters and into the first half of Sunday across the
outer waters. Do not think steep and hazardous seas criteria will
be met, but it`s not impossible either. Otherwise, winds and seas
look to remain mostly below advisory thresholds during the upcoming
week across our waters except across the central Oregon waters from
time to time when northerly winds may temporarily spike up to 25 kt
during the afternoon and evening hours. /Neuman
OR...Excessive Heat Watch from Monday morning through Tuesday
evening for Central Columbia River Gorge-Central
Willamette Valley-Greater Portland Metro Area-Lower
Columbia-South Willamette Valley-Upper Hood River Valley-
Western Columbia River Gorge.
WA...Excessive Heat Watch from Monday morning through Tuesday
evening for Central Columbia River Gorge-Greater Vancouver
Area-I-5 Corridor in Cowlitz County-Western Columbia River
PZ...Small Craft Advisory for winds until 3 PM PDT Sunday for Waters
from Cascade Head to Florence OR from 10 to 60 NM.
Small Craft Advisory for winds until 3 AM PDT Sunday for
Coastal waters from Cascade Head to Florence OR out 10 NM.
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This discussion is for Northwest Oregon and Southwest Washington
from the Cascade crest to 60 nautical miles offshore. This area is
commonly referred to as the CWA or forecast area.
Area Forecast Discussion...UPDATED
National Weather Service Tampa Bay Ruskin FL
815 PM EDT Sat Jul 21 2018
A weakening MCS pushed through the northern portion of the
area this afternoon producing some gusty winds across the
Nature Coast. At the present time, just a few light showers
remain across Highlands and Charlotte counties but most
spots are currently dry under mostly cloudy skies. For the
overnight, forecast is a bit tricky as its difficult to
determine if the aforementioned MCS remnants have
stabilized the northeast Gulf enough to impact any
nocturnal/morning showers activity from Tampa northward that
we would typically expect with the mid/upper level pattern
in place across the region. Recent runs of the HRRR keep
much of the area dry overnight but with deep moisture in
place and favorable dynamics feel its prudent to at least
keep some mention of PoPs in the forecast areawide
overnight. Current forecast has a handle on things well so
no changes made at this time for the evening update. That
being said, forecast remains tricky and showers and storms
could develop at any time so additional updates could be
needed over the next few hours. Overnight conditions will
be quite warm and muggy with coastal locations not getting
out of the 80s with some mid and upper 70s expected inland.
VFR expected outside of any showers and storms. Southwest to
west winds are expected overnight around 5 to 10 knots.
Winds will increase during the day Sunday in the 10-15 kt
range with higher gusts likely. Showers and storms will be
possible at any time with moist SW flow regime so localized
MVFR/IFR reductions can be expected in and around storms.
Elevated winds and choppy seas will be the rule through the
rest of the weekend and into early next week. Winds are
expected to increase tonight to near cautionary levels
across much of the forecast waters out of the west...and
remain at or above 15 knots into Monday. Conditions will
also favor scattered to numerous showers and storms.
.Preliminary Point Temps/PoPs...
TPA 81 89 80 88 / 30 40 40 60
FMY 79 91 80 90 / 50 60 40 60
GIF 77 92 78 89 / 20 60 30 60
SRQ 81 88 82 88 / 30 50 40 60
BKV 79 90 77 89 / 30 60 50 50
SPG 80 90 80 89 / 30 40 40 60
FL...High Rip Current Risk through Sunday evening for Coastal
Charlotte-Coastal Hillsborough-Coastal Lee-Coastal
Beach Hazards Statement through Monday evening for Coastal