Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/04/16
Area Forecast Discussion
National Weather Service Bismarck ND
1000 PM CDT SAT SEP 3 2016
.UPDATE...
Issued at 1000 PM CDT Sat Sep 3 2016
Convection starting to fire off across Sheridan and Wells County
as High res models suggesting along the frontal zone, just an
hour or two later than previously thought. Inherited pops still on
track, but did tweak blending official grids with the last two
runs of the HRRR. Will then see increasing chances and coverage of
showers/t-storms southwest spreading north and east through the
overnight and morning.
UPDATE
Issued at 712 PM CDT Sat Sep 3 2016
Scaled back on thunder wording northwest and partially north
central tonight with models showing little if any instability.
Followed this trend Monday and Monday night as well with best
chance for lightning/thunder south and east. Otherwise inherited
pops are on track along with the other forecast parameters. Will
keep an eye on fog potential though HRRR not very exciting about
this given a steady north/northeast wind near 10KTs tonight.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 258 PM CDT Sat Sep 3 2016
The main focus for the short term is heavy rain and potential
severe weather.
A deep and well developed west coast trough will continue to
slowly move east over the next several days. This will lead to
increasing flow and moisture advection.
Late this afternoon and evening a cold front, currently bisecting
North Dakota, will be the focus for thunderstorm development.
Mesoanalysis indicates 30 to 60 knots of shear and 1,000 to 2,000
J/Kg CAPE are positioned along the front. There is a marginal
threat for severe weather during the late afternoon and evening
hours across central and east central North Dakota if
thunderstorms do develop. Short-range models are depicting a cap
over the area through the late afternoon hours. This will limit
convective potential until the cap erodes or forcing pushes
through the cap. The short-range models are favoring the Bismarck
to Jamestown corridor for storms this late afternoon and evening.
Tonight a Deepening surface low and upper level jet streak will
nose into southern North Dakota. This will begin our widespread
rain event in Earnest. There is the potential for heavy rain with
high precipitable water values (near 99th climatological
percentile) for this time of the year. Storms are expected to
develop along the front and slowly propagate northeastward. The
front will be slow to move out and with strong and persistant
moist inflow prolonged heavy rainfall is possible. The latest
model guidance suggests moderate to heavy rainfall across the
James river valley Sunday and Sunday night with 2 to 3 inches of
rainfall and locally higher amounts possible.
Sunday also brings the potential for severe storms. Models are
forecasting stronger wind shear and CAPE Sunday focused along the
cold front along the James river valley. With the moderate to
strong wind shear aligned with the cold front the thunderstorms
are forecast to quickly form into lines and possibly bowing line
segments bringing the initial threat large hail transitioning to
damaging winds. An SPC slight risk is out for this area sunday
and sunday evening. There is still some uncertainty though as to
how these storms will evolve. Morning convection may limit
afternoon heating and destabilization and could limit the overall
severe threat.
.LONG TERM...(Sunday night through Saturday)
Issued at 258 PM CDT Sat Sep 3 2016
The remainder of the week will see several more shortwaves moving
through persistent southwest flow aloft as the upper level
longwave trough remains across the region. This will lead to an
active but cool weather pattern with chances for thunderstorms
each day and cool temperatures in the 60s and 70s. .
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 712 PM CDT Sat Sep 3 2016
Isolated to scattered thunderstorms possible for KJMS this
evening, otherwise VFR through 06Z. Overnight into Sunday
morning, showers and thunderstorms will develop especially over
southern and eastern locations. Widespread MVFR cigs with
localized IFR cigs will develop along with reduced visibilities in
precipiation towards 12Z. This trend will continue after 12Z for
all terminals.
&&
.BIS Watches/Warnings/Advisories...
NONE.
&&
$$
UPDATE...NH
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...NH
Area Forecast Discussion
National Weather Service Denver/Boulder CO
823 PM MDT SAT SEP 3 2016
.UPDATE...
Issued at 823 PM MDT Sat Sep 3 2016
The nose of a 80 knot jet is moving into Colorado this evening.
This is producing scattered showers and thunderstorms over the
mountains and Front Range. Appears there are CSI bands over
Boulder county at this time bringing moderate rainfall. As the
airmass stabilizes and the jet moves overhead expected the showers
and storms to decrease.
Farther east on the plains, the stronger storms have moved east of
the forecast area and into Yuma county. Outflow from these storms
has brought easterly winds and higher dew points. The HRRR is
showing fog for parts of the northeast plains. If skies are able
to clear later tonight and allow for radiational cooling, fog
seems reasonable. Will add patchy fog to the grids for the
northeast plains.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 321 PM MDT Sat Sep 3 2016
Thunderstorms continue over the high country...and have been
transitioning to the plains this afternoon. A boundary from
Wyoming is helping thunderstorm development in Weld County. We
still have the best instability in the northeast corner...and we
may see a few severe thunderstorms out there this afternoon. Still
expect storms on the plains to move out of the area later this
evening...with just a few showers or thunderstorms continuing in
the mountains.
We will have brisk southwest flow across the forecast area
developing during the day Sunday...this will usher in some drier
air...the question is whether we flush the low level moisture to
the border per the nam...or does some of the low level moisture
linger? The nam is frequently too aggressive with low level
drying...so leaving isolated thunderstorms in the northeast corner
sunday afternoon.
Our forecast temperatures were a bit higher that guidance on
sunday...so split the difference.
.LONG TERM...(Sunday through Friday)
Issued at 321 pM MDT Sat Sep 3 2016
A generally drier pattern will set up for the week ahead except
for a weak system moving over the state Tuesday. Flow across the
state will transition from southwesterly tomorrow night and Monday
to more westerly after a short wave trough passes on Tuesday. The
westerly flow aloft for the rest of the week will bring dry air
over the region. Tuesday will be the last chance for any
subtropical moisture to be over the state. The cool surge on
Tuesday may be just as related to outflow from convection over
Nebraska and South Dakota rather than a change of airmass. The
passing trough on Tuesday will be fairly progressive, so afternoon
convection associated with the upper system will be quick to move
out of the area Tuesday night.
After that, warmer temperatures and drier conditions will prevail.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 823 PM MDT Sat Sep 3 2016
Scattered showers will remain possible through 06z with only a
slight chance for thunderstorms. Easterly winds are expected to
turn southerly around 06z. Fog will be possible over the northeast
plains. This is expected to stay to the northeast of the Denver
area, but can`t totally be ruled out at KDEN. It will be drier
Sunday with breezy southwest winds possible after 18z.
&&
.BOU Watches/Warnings/Advisories...
None.
&&
$$
UPDATE...Meier
SHORT TERM...RTG
LONG TERM...Dankers
AVIATION...Meier
Area Forecast Discussion...UPDATED
National Weather Service BROWNSVILLE TX
704 PM CDT SAT SEP 3 2016
.DISCUSSION...Updated for latest aviation discussion below.
&&
.AVIATION...Ongoing isolated late afternoon/early evening
convection will wane as heating diminishes. Nonetheless, a few
additional showers moving onshore from the Gulf will dance around
BRO in the next hour or two. Otherwise, we are expecting primarily
VFR Tafs tonight with mostly clear skies and light winds. The HRRR
suggests convection will move in from the Gulf around dawn Sunday
as overall moisture increases and activity in the Southwest Gulf
becomes more active, moving north along the coast. The NAM
advertises scattered showers and thunderstorms from mid morning to
mid afternoon, with broken to overcast skies. VFR ceilings will
develop, possibly decreasing briefly to MVFR in the afternoon.
Light east morning winds will become light to moderate southeast
by afternoon.
&&
.PREV DISCUSSION... /issued 251 PM CDT SAT SEP 3 2016/
SHORT TERM (Tonight through Sunday Night): After
seabreeze/afternoon convection winds down later this evening...we
will likely see dry conditions over the inland areas with the
typical nocturnal showers setting up over the coastal waters. Models
continue to show elongated high pressure extend from the mid CONUS
down into south Texas...with ample dry air in the mid levels.
Meanwhile...an inverted trough will approach from the Bay of
Campeche overnight. It appears that the upper level ridge will help
direct the the upper level wave north and west...generally in to
the north central Mexican coastline.
However...there will be at least some moistening of the atmospheric
column as deep layer moisture increases as the trough moves through
the Deep South Texas and the RGV. Have made some increases to POPs
to mention more of a chance for showers and
thunderstorms...especially by mid to late morning Sunday into the
afternoon hours. There may be slight decrease in coverage over the
eastern portions over region before another wave of moisture moves
through Sunday night into the early morning hours on Monday.
Rainfall amounts will be modest...with some places picking up half
an inch to an inch. One thing to note...is that with the dry air in
place it will take time to moisten the atmosphere...which is why I
have not increased POPs as much as some model guidance suggests.
Cloud cover and rainfall will keep temperatures a bit cooler than of
late...with readings closer to normal.
LONG TERM (Monday through Saturday): In the Mon-Thu time frame,
the forecast area to be under the influence of building strong
high pressure centered over/near Alabama. The upper flow over
deep south Texas looks to shift from south early in the period to
easterly toward the middle of the coming work week as the center
of the strong upper high is slated to transition to east central
TX/west central LA. Chances of precipitation for the entire period
start off the highest at the beginning of the period as the area
remains under a relative surge of tropical moisture. Chances of
precipitation rapidly decline Tuesday and bottom out to near zero
by Wednesday and continue that was through much of the rest of the
week as the upper high over Alabama builds toward the Rio Grande
Valley. Models are showing a weak easterly/tropical wave
approaching then moving into the Rio Grande Valley Fri/Sat, but at
this time, am not seeing a big increase in moisture across the
area associated with it. For now, will leave low/no chances of
precipitation alone for late next week, but will not be surprised
if there is an appreciable increase in moisture for that time
period as we progress through next week. Overall, both high and
low temperatures look to remain above seasonal norms through the
entire period.
MARINE (Tonight through Sunday Night): A generally weak surface
pressure gradient will keep light East to Northeast winds in place
through the evening. High pressure will build over the Northern Gulf
as inverted troughing moves over the Southern Gulf waters and along
the South Texas coastal water Sunday and Sunday night. Winds will
turn more southeasterly and speeds will increase. Seas will come up in
response...more in the 2 to 4 foot range. Shower and thunderstorm
activity will also increase through the end of the period.
Monday through Thursday: a weak pressure gradient over the
northwest Gulf will maintain modest winds/seas over the forecast
area through the period.
&&
.BRO Watches/Warnings/Advisories...
TX...None.
GM...None.
&&
$$
This product is also available on the web at:
HTTP://WEATHER.GOV/RGV
54/66
Area Forecast Discussion
National Weather Service Medford OR
853 PM PDT SAT SEP 3 2016
.SHORT TERM...An upper level low will move into the area tonight
and shift eastward on Sunday. The main effect with this feature
will be to bring some showers and a slight chance of thunderstorms
to areas east of the Cascades tonight. The latest high resolution
HRRR model shows showers developing this evening and tonight in
the Modoc and Lake County areas and possibly into far southeast
Siskiyou. The NAM and GFS also support similar scenarios with
their focus of activity in Modoc, Lake and far eastern Klamath
counties. Elevated instability, divergence aloft and lift
associated with this low are also expected to bring a slight
chance for thunderstorms tonight into Sunday morning. Have
expanded the chance for showers and thunderstorms slightly tonight
into Sunday morning to match these latest model forecasts.
Clouds associated with this low may keep east side low
temperatures warmer than last night. Still expect a cool night as
a colder air mass is in place. A frost advisory and freeze warning
are in place for many eastern locations. See the NPWMFR for
details. Of note, clearing skies Sunday night and a cooler air
behind this low will bring likely freeze and frost conditions for
areas east of the Cascades Sunday night and Monday morning.
West of the Cascades expect low clouds tonight and Sunday morning
along the coast and inland into Southwest Oregon. Temperatures
during the day Sunday will be cooler with highs in the low to mid
70s. East side valleys are expected to only reach high
temperatures in the mid to upper 60s on Sunday.
&&
.AVIATION...Despite the scattered cumulus clouds east of the
Cascades and north of the Umpqua Divide, VFR conditions currently
prevail across the area. An incoming shortwave will provide a
significant marine push tonight and also possibly kick off
isolated thunderstorms east of the Cascades overnight. IFR
conditions are expected to return to the coast late tonight, with
MVFR cigs developing in the Umpqua Basin and other west side
valleys. Smoke from the Gap Fire will bring IFR to MVFR
visibilities from Happy Camp eastward up the Klamath River
Canyon...to near Interstate 5 and southward through the Shasta
Valley. Otherwise, all areas should remain VFR throughout the TAF
period. /BR-y
&&
.MARINE...Updated 200 PM PDT Saturday 3 September 2016...A thermal
trough will continue to produce gusty north winds and choppy seas.
Small Craft Advisory conditions south of Cape Blanco will persist
through Monday evening, with a brief period of very steep and
hazardous seas this evening south of Cape Ferrelo. A front will move
onshore Tuesday...then offshore high pressure will build Wednesday.
-BPN
&&
.PREV DISCUSSION... /Issued 230 PM PDT SAT SEP 3 2016/
DISCUSSION...A long wave trough remains over the Pacific
Northwest with a short wave shown on the models off the central
Oregon coast. IR satellite images don`t show much cloud with it
but it does appear in the water vapor images. Moisture and
instability are rather limit with the wave. Some moisture does
increase from the south when the wave reaches Lake County. The
showers will not be driven by instability but rather dynamically
by upper level divergence associated with the short wave. Chance
of precipitation has been scaled back a bit except for Lake and
Modoc Counties for tonight and into Sunday. A dry and stable
northwest flow sets in for Monday before another weak short wave
rotates around the trough to affect the area on Tuesday. This
system will mainly bring a slight chance of showers to Coos and
Douglas Counties. The area then gets under a dry northwest flow
for the remainder of the week with a slow warming trend.
Temperatures this morning were rather cold across much of the area
east of the Cascades. Expect cold temperatures again tonight so
freeze warnings and frost advisories are issued. The questionable
area for the freezing temperatures is Lake and Modoc Counties.
Cloud cover and mixing may keep their overnight lows higher than
currently forecast. Most eastside areas will be cold again Sunday
night/Monday morning. Overnight temperatures warm through the
remainder of the week with only the typical cold locations, such
as Chemult and Christmas Valley, lingering near freezing. JBL
FIRE WEATHER...Updated 100 PM PDT Saturday 3 September 2016...
Temperatures near to as much as 10 degrees below normal and good
relative humidity recoveries will prevail through Sunday night. This
afternoon and evening will feature breezy northwest to west winds
across the forecast area. An upper low will move through from the
northwest tonight, and models have consistently shown some shower
and thunderstorm potential, focused mainly over Lake and Harney
Counties late tonight and early Sunday morning. There will likely be
some rain with these storms given relatively slow motion expected
per the weak H5-H7 steering flow.
Monday will be a relatively dry morning and day, with moderate high
terrain humidity recoveries and afternoon humidities in the 15-25%
range. An upper trough will approach the area early Tuesday and bump
humidities back up, and it will bring a chance for rain to mainly
the northern sections of the forecast area.
After Tuesday, a steady warming and drying trend is expected through
Friday, agreed upon by the GFS and EC. After that, there are
substantial differences between the GFS and EC...and between GEFS
members. Some of these differences could be due to Hurricane Lester
and how the models handle that energy as it moves north and gets
injected into the westerlies. SK
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Frost Advisory from 3 AM to 7 AM PDT Sunday for ORZ029>031.
Freeze Warning from 3 AM to 7 AM PDT Sunday for ORZ029>031.
Freeze Warning from 3 AM to 8 AM PDT Monday for ORZ029>031.
CA...Frost Advisory from 3 AM to 7 AM PDT Sunday for
CAZ080-082-084-085.
Freeze Warning from 3 AM to 7 AM PDT Sunday for CAZ082-084-085.
Freeze Warning from 3 AM to 8 AM PDT Monday for CAZ082-084-085.
Pacific Coastal Waters...Small Craft Advisory until 5 AM PDT Tuesday for PZZ356-376.
Hazardous Seas Warning until 5 AM PDT Sunday for PZZ356-376.
$$
CC/CC/CC
Area Forecast Discussion
National Weather Service Omaha/Valley NE
644 PM CDT SAT SEP 3 2016
.SHORT TERM...(tonight through Tuesday)
Issued at 315 PM CDT SAT SEP 3 2016
The main forecast concerns are in regards to thunderstorm chances
for the next few days.
Main features from the 12z upper air charts include the following.
At 300 mb...a jet streak of around 90 knots at 300 mb was noted
from western Montana into Saskatchewan. This was in the somewhat
confluent mid level flow ahead the trough that extended from
Alberta down to off the central California coast. 12 hour 500 mb
height falls were generally 20 to 60 meters east of the trough.
Monsoonal 700 mb moisture was highest from Mexico northward into
southern and western Colorado...with dewpoints of 5 to 8 degrees
Celsius. Thermal ridge at 700 mb stretched from New Mexico up into
Manitoba and western Ontario. Moist axis at 850 mb stretched from
Texas and New Mexico northward into the Dakotas. The 12Z KOAX
sounding only showed about 0.72 PW but had modest lapse rates
above 700 mb. Showers and thunderstorms to the west today have
produced some local rain amounts near an inch.
Some of the hi-res short range models tend to break up the
activity currently between Omaha and Hastings. Although the RAP13
model may be a bit overdone with amounts and coverage...it
appeared at least reasonable with its forecast this evening. Will
keep rain amounts mostly under 0.25 inches but heavier amounts are
possible. KLNK soundings from the RAP model show elevated CAPE of
around 400 J/kg with parcels originating around 750 mb. Eventually
that will spread toward KOMA. PW values are expected to increase
into the 1.5 to 2.0 inch range tonight...as a low level jet of
40-45 knots develops. RAP and some recent runs of the ESRL HRRR
show precipitation lasting into at least Sunday morning before
mostly lifting off to the northeast. Will stay fairly close to the
previous forecast highs of 80 to 85...with the warmest values in
our western counties.
The main area of convection by late Sunday afternoon should be
over the Dakotas...along and behind a cold front. Storms may
develop southward into the moist axis as a low level jet of 50-55
knots develops in the evening. Chances before midnight will be
highest in our northern counties...but will probably develop
farther south after midnight. Some severe storms appear possible
mainly in northeast Nebraska.
At this time...we have Monday as mainly dry. Decent pressure
gradient and mixing should bring breezy/windy conditions and highs
near 90 or in the lower 90s. Convection will be possible Monday
night but best forcing will likely stay to our west and north.
Storm chances should be highest in northeast Nebraska in the
evening. Shear and instability parameters support the slight risk
shown in the SPC Day 3 outlook.
By 12Z Tuesday...the 500 mb trough axis should extend from Alberta
to southern California...with our area remaining in modest
southwest mid level flow. We will also likely still be in the high
PW plume extending up from Mexico. Model agreement is only fair on
how things will play out for Tuesday. The 12Z ECMWF is more
generous with precipitation during the day for our area compared
to the GFS. Kept highest chances now in our northern zones.
.LONG TERM...(Tuesday night through Saturday)
Issued at 315 CDT SAT SEP 3 2016
Pattern for Tuesday night suggest heavy rain potential along with
a risk of severe storms with a slow moving front in our northern
areas. That is forecast to push south Wednesday and Wednesday
night. Kept rain chances highest near the front and expect some
drier air to move into northeast Nebraska by 12Z Thursday. By
that time...the 500 mb flow should be more zonal. Thursday rain
chances seem pretty low but will increase Thursday night as
southerly lower tropospheric flow increases. Models are in fairly
good agreement that a modest shortwave trough will approach from
the northwest Friday. There are some timing differences but it
should turn drier and cooler by Saturday.
&&
.AVIATION...(00Z TAFS for KOFK...KLNK and KOMA.)
Issued at 640 PM CDT SAT SEP 3 2016
Scattered showers will affect KLNK and KOMA through about 04Z
before moving off to the northeast. More showers or thunderstorms
are forecast to develop after 09Z near KOMA and KLNK, but coverage
is expected to be isolated. Otherwise VFR conditions are forecast
at those sites. At KOFK, rain should remain southeast of that
area, but lower clouds near FL015 are expected to spread across
the TAF site around 08Z and linger through much of the morning.
There is a chance for IFR cigs and MVFR fog at KOFK for a few
hours either side of 12Z. By 18Z, all eastern Nebraska TAF sites
will see VFR conditions with south winds increasing into the 15 to
25 kt range.
&&
.OAX Watches/Warnings/Advisories...
NE...None.
IA...None.
&&
$$
SHORT TERM...Miller
LONG TERM...Miller
AVIATION...Dergan
Area Forecast Discussion...UPDATED
National Weather Service Reno NV
717 PM PDT SAT SEP 3 2016
.UPDATE...
Forcing ahead of upper level trough has been a little more robust
this evening with a number of lightning strikes near Ravendale in
northeast California. Updated to extend mention of showers
westward to Eagle Lake and add a mention of thunder along this
band for the evening hours. Latest HRRR indicates a decent band of
showers forming along cold front near daybreak over northwest NV
and moving east-southeastward Sunday morning as main upper trough
swings through the region. Hohmann
&&
.PREVIOUS DISCUSSION... /Issued 232 PM PDT SAT SEP 3 2016/
SYNOPSIS...
Low pressure will bring cool conditions with periodic breezes
into Tuesday. A few showers are possible north of Interstate 80
Saturday night and Sunday. Freezing temperatures are likely for
Sierra valleys Monday and Tuesday mornings, with spotty frost for
some western Nevada valleys. Warm and dry conditions are forecast
for the second half of next week.
SHORT TERM...
Low pressure over Oregon will move across northern Nevada tonight
and Sunday, bringing a preview of autumn weather for Sunday and
Labor Day. A few showers and thunderstorms remain possible north
of Portola to Lovelock tonight and Sunday but any precipitation
amounts will be less than a tenth of an inch.
Southwest to west winds this afternoon will shift to the northwest
and north for tomorrow as the low passes. Don`t expect any
widespread wind impacts, but there will be a few locations where
gusts reach 30 mph.
Overnight lows may be an issue Monday and Tuesday mornings as
clear skies and dry air allow for good radiational cooling. Lows
in the 20s are likely in most Sierra valleys. Across western
Nevada most locations will cool into the 40s, but could see the
typically colder valleys drop into the mid to upper 30s. Brong
LONG TERM...Tuesday through Saturday...
Minimal changes to the long term forecast today. Broad trough over
the interior west will continue to weaken and lift eastward through
the second half of the week. Shortwave moving through the trough
will bring a slight chance of precipitation near the Oregon border
on Tuesday. It still looks like the best chances of precipitation
will remain north of the border and bring only an increase in
cloudiness to the northern portions. Tuesday could also see
increased breeziness with near normal to light afternoon winds
thereafter.
Dry northwest flow will take over the rest of the week as high
pressure builds off the west coast. This will allow temperatures to
slowly warm up reaching to near 90 in western Nevada and low 80s the
Sierra by next weekend. -Zach
AVIATION...
VFR conditions with winds gusting 20-30 kts this afternoon. Light
radar returns are evident from KMMH to KWMC as a weak cold from
moves through the area. Another round of light showers will be
possible tonight from Pyramid Lake north to the Oregon border though
QPF is expected to be light, around 0.05 in. -Zach
&&
.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&
$$
For more information from the National Weather Service visit...
http://weather.gov/reno
Area Forecast Discussion
National Weather Service Blacksburg VA
800 PM EDT Sat Sep 3 2016
.SYNOPSIS...
Hermine is expected to move slowly northeast off the mid Atlantic
coast tonight before stalling offshore the Delmarva region Sunday
into early next week. High pressure behind Hermine should remain
over the area during the next few days resulting in continued dry
weather. The storm system should finally drift farther northeast
and away from the mid Atlantic coast by mid to late week.
&&
.NEAR TERM /THROUGH SUNDAY/...
As of 745 PM EDT Saturday...
Most models show a elongated east-west weak trough drifting
southward across the region from northern WV/northern VA overnight
into Sunday morning. This is associated with a chaotic pattern
which involves a deeper uptrough just off the Delmarva, T.S.
Hermine, and high pressure aloft building over the OH Valley.
Nearly all models show fairly significant moisture in the
850-700mb layer accompanying this feature as it drifts southward
across the region overnight/Sunday morning. Indeed there have been
some light rain showers developing/drifting back into the VA
Piedmont as a result. HRRR shows light rain drifting southward
overnight in east-west spiral bands, and while this may be a bit
overdone, all models suggest moisture in a similar configuration.
Thus, have added low pops to the Piedmont and may need to increase
cloud cover overnight as well in the west.
As a result of the clouds east and sun west, dewpoint values were
too low in the east, so needed to raise those on average about 3F.
Temperatures only needed minor adjustments.
As of 230 PM EDT Saturday...
Hermine has moved off the Outer Bank of North Carolina this
afternoon. With Hermine off the coast, the area is under strong
subsidence with winds 10-15 mph with a few gusts up to 25 mph. Some
outer cloud bands have moved back across the piedmont and may spit
out a few sprinkles this afternoon then erode overnight.
Even though Hermine has everyone`s attention, there still exists an
upper level low/trough overhead. This weakness in the upper levels
will generate more clouds for tomorrow and maybe a few
sprinkle/showers across the mountains. Even though each model is
displaying isolated rain showers over the mountains, none are in the
same place. With mostly a dry airmass remaining, kept showers out of
the forecast for tomorrow. If showers do develop, they may only
produce enough rain to just wet the ground.
Dewpoints will remain dry (in the 50s), so once the sun goes down
the thermometer will retreat quickly across the mountains into the
60s this evening, and into the 50s for lows overnight. Some valleys
may dip into the 40s. Afternoon clouds may hang on across the
piedmont, possibly being trapped under an inversion. These clouds
may only allow temperatures to drop into the lower 60s from
Lynchburg to Danville east.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/...
As of 230 PM EDT Saturday...
Overall dry weather looks to prevail as the region remains in between
Hermine offshore the Delmarva and strong mid level ridging just west of
the mountains into early next week. Models do show an apparent final
piece of shortwave energy sliding south east of the mountains Sunday
night under strong northerly flow on the back of the stacked upper low
offshore. Guidance suggests this may bring a swath of clouds back
toward the Blue Ridge later Sunday night while the boundary layer shows
too much dry air for much rainfall.
Thus including a bit more cloudiness Sunday night per the passing vort
lobe but without pop. Otherwise mainly sunny/clear under dry northerly
breezes through the period. Should remain comfortable under rather low
dewpoints with lows mostly 50s Sunday night, then bumping into the 60s
east Monday night. Highs Monday upper 70s/around 80 mountains to the
mid 80s east as warming aloft starts to take shape.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
As of 200 PM EDT Saturday...
Hermine progged to meander off the Mid-Atlantic coast through at least
mid week before finally booting east ahead of the next upstream 500 mb
trough that will approach late in the week. This should again keep a
dry northerly flow in place early in the period under increased
subsidence as heights build ahead of ridging aloft sliding in from the
west. Flow should become more zonal later in the week into early next
weekend in response to gradual digging of northern stream energy that
will tend to flatten high heights across the region. This should also
allow for a gradual return of low level moisture by Friday ahead of a
weak front to the north and a stronger upstream cold front on Saturday.
Appears enough moisture with orographics and heating to support
mainly diurnal chance pops west Friday and perhaps a little better
coverage Saturday. Otherwise will remain quite warm for early
September under very warm 850 mb temps and plenty of sun for most
of the period. Latest blend supports highs mid/upper 80s mountains
to low/mid 90s east, with a gradual increase in humidity through
Saturday.
&&
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
As of 750 PM EDT Saturday...
A VFR forecast expected through the period, but it will not be
SKC. T.S. Hermine lingers off the Delmarva coast. With a chaotic
upper air pattern in place across the Mid-Atlantic involving T.S.
Hermine, an upper low over the top of Hermine, and high pressure
aloft building across the OH Valley, a weak east-west upper trough
has emerged on the back side of Hermine into the Appalachians. All
models have picked up on this feature. This will bring mid clouds
to most areas overnight/Sunday morning before drifting southwest
and dissipating Sunday afternoon. Even a few sprinkles are
possible, as noted on radar, across the Piedmont, but this is too
insignificant to include in the KLYH or KDAN TAF at this time. It
likely will remain east of these sites as well. All associated
cloud bases are expected to be 050 or greater, mostly in the
080-150 range.
Fog development is not expected due to aforementioned clouds.
Wind still being influenced by T.S. Hermine off the east coast.
This is keeping the direction NE-NNE in most areas, but variable
direction or southeast being noted west of the Blue Ridge at
times. Little change in the wind direction pattern is expected
through the TAF valid period. Speeds are expected to be less than
10kts, strongest east of the Blue Ridge closest to Hermine. Have
removed all mention of gust as it has been several hours now since
gust has been reported.
Medium to high confidence in cigs throughout the TAF valid period.
High confidence in VFR vsbys throughout the TAF valid period.
Medium confidence in wind direction and speed throughout the TAF
valid period.
Extended aviation discussion...
Generally VFR conditions expected through much of the extended
period as Hermine lingers off the mid-Atlantic coast for several
days into the mid part of next week. This will put our area in a
subsidence zone for several days. Early morning/late night fog
development may evolve as low-level moisture slowly increases
during the mid and later part of next week, but very little
expected through the early part of next week.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...JH
NEAR TERM...RAB/RCS
SHORT TERM...JH
LONG TERM...JH
AVIATION...RAB/RCS
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
825 PM EDT SAT SEP 3 2016
.UPDATE...
00Z water vapor and H4 RAP analysis shows upper level ridging
slowly building back over the Florida peninsula in the wake of
Hermine. Hermine is now spinning off the mid-atlantic coastline
and expected to impact that region for the next several days. With
Hermine well to our north now...our local weather will continue to
slowly improve through the remainder of the holiday weekend. There
remains quite a bit of atmospheric moisture around...and plenty of
saturated soils...so developing showers will not be difficult for
the next several days. However...no significant areal rainfall is
expected...but rather the more typical late summer diurnal showers
and storms.
For the next few hours...most of the shower and storm activity is
off to the north of the forecast area. However...watching a
convective outflow boundary moving eastward toward the coasts of
Manatee/Sarasota/Charlotte and Lee counties. If this boundary
makes it to the coast...then a few brief showers are certainly
possible between 9PM and midnight. A few additional showers are
likely to continue well inland in the vicinity of Highlands county
as boundaries move into that area from the east. The convection
over these south-central zones should dissipate after 11 PM with
the complete loss of diurnal heating.
Elsewhere and into Sunday and Monday...the forecast looks on
track and little value can be added to the previous discussion
below.
&&
.AVIATION (00Z Issuance)...
General VFR conditions expected through the TAF period for all
terminals. Slight potential for some light MVFR BR around KLAL
late tonight...but no significant restrictions are expected. VFR
continues with light east flow becoming onshore near the coast in
the afternoon/early evening. Widely sct afternoon storms possible
around each terminal...mainly after 18Z.
&&
.Prev Discussion... /issued 321 PM EDT SAT SEP 3 2016/
SHORT TERM (Today and Sunday)...
Large scale upper troughing extends from central Canada southward
into the Pacific Northwest with upper ridging from the Southern
Plains region north and east into the Great Lakes and Southeast.
Hermine continues to move northeastward this afternoon within a
weakening flow regime, and is expected to slow to a near
stationary movement over the next 24 hours off the Mid-Atlantic
coast.
For today, a remnant trough in the wake of Hermine continues to
generate clusters of showers and thunderstorms over the warm Gulf
waters. Earlier, this activity moved ashore with a noted outflow
boundary. In the wake of this boundary, the airmass was stabilized
and little in the way of thunderstorm activity has developed north
of the I-4 corridor. Further south, isolated thunderstorms have
developed along the seabreeze and this activity is expected to
gradually shift further east through the evening. The presence of
the surface trough will continue to generate convection over the
Gulf of Mexico, some of which may affect areas from Tampa Bay
north along the Nature Coast. Given recent trends in radar and the
stabilized environment, have lowered PoPs significantly through
the evening in these areas.
For tonight, some lingering showers may continue to impact the
Nature Coast as the trough lifts northward and slowly weakens.
On Sunday, showers may linger north for the first part of the
morning. Thereafter, as weak high pressure builds across the area,
expect a more typical seabreeze environment, with thunderstorms
developing over interior portions of the peninsula. This activity
may be enhanced over northern/central Florida, where the influence
of the residual surface trough remains.
Temperatures will remain a bit below climatology along and north
of I-4 today where greater cloud cover exists, but will warm to
near normal in the upper 80s and low 90s Sunday. Lows will be
seasonable with mid 70s common.
MID TERM/LONG TERM (Sunday Night-Saturday)...
Ridging aloft centered over the Lower Mississippi Valley builds
in across the Gulf region then relaxes and drifts west during the
end of the week. Hermine meanders over New England coastal waters
through midweek with a swath of higher moisture strung out across
FL. Then for the last half of the week Atlantic high pressure
ridges west...along the GA/FL line.
Ample moisture generally remains in place through the period for
scattered to occasionally numerous showers and thunderstorms...
mainly in the afternoon and early evening. The exception may be
across the north were some slightly drier air moving in may
suppress the rain chances briefly. however moisture will return to
the north in the end of the period when east and southeast flow
sets up. Temperatures will remain near to just below normal.
MARINE...
Light southwest flow will continue over the waters through this
evening as a weak surface trough remains over the northern waters.
Winds will become southeasterly overnight as high pressure begins
to slowly build into the region. As this surface ridge continues
to build through the first half of next week, east to northeast
flow will persist over the waters. At this time, winds look to
generally remain below 15 knots outside of any marine
thunderstorms that occur, and seas look to stay below 2 to 3 feet.
FIRE WEATHER...
A seasonably warm and moist summer weather pattern will continue
over the next week, with daily chances for rain. This will
maintain relatively high afternoon humidities and no fire weather
concerns are expected.
HYDROLOGY...
Several area rivers are either experiencing ongoing flooding or
area forecast to go into flood stage. Depending on how much rain
falls over the next few days, river forecasts may increase and
river flooding may worsen. Please follow local emergency
management sources for any evacuation information.
&&
.Preliminary Point Temps/PoPs...
TPA 76 89 77 90 / 10 30 20 50
FMY 76 92 76 91 / 10 30 30 60
GIF 73 91 75 90 / 20 40 30 50
SRQ 76 89 76 89 / 10 20 20 50
BKV 73 89 73 91 / 20 50 30 40
SPG 77 89 79 90 / 10 30 20 50
&&
.TBW Watches/Warnings/Advisories...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION...Mroczka
Previous Discussion...Austin/Carlisle
Area Forecast Discussion
National Weather Service Bismarck ND
350 AM CDT SUN SEP 4 2016
.SHORT TERM...(Today and tonight)
Issued at 329 AM CDT Sun Sep 4 2016
A significant jet streak at h300 is forecast to move northeast
from the four corners region into the upper plains today and
tonight. Co-incident with this, a northern stream 100+ kt jet is
over topping a broad ridge across southern Canada creating
significant diffluence aloft between the two features. This will
act in tandem to create a large and persistent upward motion field
across North Dakota and in turn increase the low level jet
pulling moisture into the region. Other important factors such as
a two standard deviation from normal precipitable water anomaly
will support wide spread showers and thunderstorms across the
state today and tonight.
The first push of precipitation is moving into southwest north
dakota this morning. Now finally seeing the expected line of
storms forming in northeast North Dakota along the frontal
boundary. This makes the pop forecast a bit complex early today
but by late morning widespread showers and thunderstorms will
connect from the southwest into the northeast. Have adjusted pops
per the latest HRRR runs for the morning hours.
The front will also be the focus for severe thunderstorms this
afternoon and evening. Current thinking is sufficient heating will
allow the cape to reach the forecast 1500-2500 the models suggest.
For this afternoon and evening a slight risk of severe thunderstorms
are noted.
Moderate to heavy rain will be the result across the James river
valley later today and tonight. Local amounts of 3 inches or a
little more will extend over sufficiently long 6 to 12 hour period
and at this time flash flooding is not anticipated. Will not issue
any headlines for this.
.LONG TERM...(Monday through Saturday)
Issued at 329 AM CDT Sun Sep 4 2016
The long term continues to look cooler and active as a broad
cyclonic flow will remain over the northern plains with several
shortwaves moving through. The superblend guidance indicated the
best chance for showers this coming week will be wednesday with a
transient short wave producing likely pops. There will be at
least a chance for showers and thunderstorms through Saturday.
Highs Monday will be the coolest with upper 50s northwest and the
60s east. Then highs will be in the 60s to lower 70s for the
remainder of the week.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 329 AM CDT Sun Sep 4 2016
Showers and thunderstorms will gradually move in from the
southwest later this morning and last through Sunday. Widespread
MVFR cigs with localized IFR cigs will develop along with the
potential for reduced visibilities in precipiation. The best chance
for thunderstorms will be at KBIS and KJMS late in the morning and
afternoon.
&&
.BIS Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...MM
Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
347 AM CDT SUN SEP 4 2016
.Discussion...
Issued at 344 AM CDT SUN SEP 4 2016
Short Range:
The surface high pressure system which kept us nice and comfy with
mild days, cool nights and pleasant humidities is slowly loosing its
influence on our weather. Surface winds have veered to the southeast
and will eventually swing around to south and south-southwest next
week.
For today we have a little fly in the ointment. A shrinking MCS over
southern NE/northern KS will work its way east this morning with rain
chances on tap for northwest MO and parts of west central MO.
Satellite trends show a slow cloud top warming indicating gradually
weakening convection, supporting a path the HRRR has been trending
towards all night. So, will weaken the convection as it moves into
northwest MO. How fast the convective debris/cloud cover dissipate is
open for debate. Should the cloud cover be slow to burn off the day
shift will need to lower max temperatures. For now will play it
conservatively and trim high temperatures by a degree or two over
northern MO.
Next Week:
For the past few days we`ve talked about how post-Tropical Cyclone
Hermine, spinning basically in the same location off the northern Mid
Atlantic Coast, would act as a block...and effectively keep our
weather in a holding pattern through Wednesday. The latest rendition
of the operational models hasn`t changed much since Friday. We
anticipate an upper level ridge to our east allowing southwesterly
flow aloft to draw layered moisture northeast. In addition there
will likely be an embedded weak upper trough or two which will
generate scattered convection over the Central Plains and eventually
spreading into the CWA. Timing seems to favor Wednesday with the
arrival of the first batch of convection. Even higher PoPs are
expected Thursday through Friday night when an upper level trough
finally moves across the north central U.S. and sends a frontal
boundary southward. Difficult this far out to determine if the front
stalls out in the CWA or north in IA as the front will run nearly
parallel to the mid/upper level flow. Overall, expect a couple
periods of showers and storms and a return to above normal
temperatures and yucky humidity.
&&
.Aviation...(For the 06Z TAFS through 06Z Sunday Night)
Issued at 1142 PM CDT SAT SEP 3 2016
VFR conditions expected through the period with only mid to high
level clouds expected. Winds should generally be from the southeast
to south through the forecast with winds increasing to between 10 and
15 kts during the afternoon.
&&
.EAX Watches/Warnings/Advisories...
KS...None.
MO...None.
&&
$$
Discussion...MJ
Aviation...CDB
Area Forecast Discussion
National Weather Service Grand Forks ND
359 AM CDT SUN SEP 4 2016
.SHORT TERM...(Today and Tuesday night)
Issued at 358 AM CDT Sun Sep 4 2016
Long wave trough forecast to remain over the western US with
many short waves moving through the flow through 84 hours.
Thunderstorms have developed over the Devils Lake basin this
morning. Precipitable water was around an inch and a half over much
of the valley. Good low level moisture transport was moving into the
area. 30-35 knot low level jet was nosing into northwest MN.
Water vapor loop indicated a short wave over northeast CO and should
move across the area this afternoon. Thunderstorm threat will
increase with short wave.
Water vapor loop indicated an upper level trough located over the
west coast with short waves embedded. One short wave was over CA/OR
border and another short wave was over southern CA.
Southern CA short wave is forecast to move into the Northern Plains
Sun night. 50 knot low level jet forecast to nose into northwest MN
Sun night. Precipitable water decreases after Mon night as
west/northwest flow dominates. Precip finally shifts east of the
area.
CA/OR short wave forecast to move into southern MAN by Tue morning
with little precip forecast.
Another short wave/jet streak will move through Tue night and
precip forecast to return north into the southern Red River Valley.
.LONG TERM...(Wednesday through Saturday)
Issued at 358 AM CDT Sun Sep 4 2016
Wednesday through Saturday...A large scale upper trough with several
embedded shortwaves will be moving through for much of the period.
The models differ on exact timing and strength of the shortwaves,
but are in general agreement on the first moving through
Wednesday/Wednesday night and another Friday with a bit of a break
on Thursday. Will keep the blended solution of relatively higher
POPs during Wednesday and Friday. Temps throughout the period should
be a bit cooler than seasonal averages with highs in the 60s and low
70s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday evening)
Issued at 1155 PM CDT Sat Sep 3 2016
Convection filling into the DVL Basin...should continue as
scattered convection acoss northeast ND /DVL to GFK/ through
10z. SPC HRRR shows convection dying after 10z. Areas on MVFR
cigs are expected across much of the FA on Sunday morning... with
sct deep convection developing across eastern ND in the early
afternoon... spreading across northwest MN through the late
afternoon.
&&
.FGF Watches/Warnings/Advisories...
ND...None.
MN...None.
&&
$$
SHORT TERM...Hoppes
LONG TERM...JR
AVIATION...Gust
Area Forecast Discussion
National Weather Service Sioux Falls SD
426 AM CDT SUN SEP 4 2016
.SHORT TERM...(Today and Tonight)
Issued at 425 AM CDT Sun Sep 4 2016
Plenty of questions on shower and storm coverage for today, with
initial early morning convection over the southeast half of the
area, roughly Brookings to Yankton area and southeast. Despite
continuing feed of moist and increasingly unstable air, the
temporary fading of the low level jet, and the pulling northeast of
a distinct short wave lobe shown on models suggest a decrease of
activity in this area later this morning into early afternoon, and
that is what we will go with for now. With MUCAPE increasing slowly
toward 2000 j/kg, storms are getting a little stronger this morning
but do not see a severe risk, yet anyway.
Expect clouds to decrease from the west through early afternoon and
some heating to set in. The big question is whether or not there
will be redevelopment of storms in the mid to late afternoon over
the same southeast half of the area, as the experimental HRRR is
starting to suggest, albeit in fairly modest coverage. Given the
approach of strong support from the west late in the day, I feel
that the redevelopment in the southeast is overdone.
Temperatures will warm a bit stubbornly into the upper 70s to lower
80s east of the James River this afternoon, and into the mid to
possible upper 80s west. Southerly/southeasterly surface winds will
again increase to the windy category but should stay short of wind
advisory levels/
This brings us to tonight and the obvious potential of widespread,
and possibly severe, showers and storms moving east across the
area, especially north. POPs will be likely to unqualified west and
north for tonight, with a decent chance south and southeast of FSD.
This seems reasonable, given the northeast movement of the upper
support, and the location of the surface front on the northwest end
of the area.
The SPC severe risk looks good, with the greater risk over southeast
SD and possibly into part of southwest MN. decent 2000-3000 j/kg
CAPE and favorable low to mid level wind fields will couple with the
upper support and good low level jet. The severe threat should fade
after the evening hours.
Loaded QPF is probably good with a widespread half inch plus of rain
tonight from FSD north and west, but there will surely be some areas
over an inch. Locally even higher amounts look possible, but given
the dry conditions lately, and the likely decent cell movement, feel
local flooding is unlikely.
.LONG TERM...(Monday through Saturday)
Issued at 425 AM CDT Sun Sep 4 2016
Active pattern will continue through much of the work week, though
latter half does show some promise for more sporadic precip chances
than do the first few days.
Labor Day could begin with isolated storms lingering in northwest
Iowa/southwest Minnesota just after daybreak, though anticipate any
activity to push east of the area/diminish by mid morning. Models
showing fairly good agreement in placing surface front from central
Nebraska/south central South Dakota, into northeast South Dakota and
northwest Minnesota early. Boundary remains nearly stationary as a
surface wave slides northeast along the front, reaching east central
South Dakota by late afternoon, with more well-defined warm front
developing just north of Highway 14 and cold front from near Huron
southward into central Nebraska. Despite what could be slightly
subsident air mass in the wake of mid level wave lifting into the
Red River Valley Monday afternoon, low level support from the
approaching surface wave warrants maintaining low pops along and
north/west of the surface boundary. Models showing fair amount of
moisture persisting below 700mb, so concerned that cloud cover could
be a little more persistent during the day and inhibit heating, and
GFS/NAM continue to be overdoing the mixing. But highs closer to the
ECMWF in the mid 80s to near 90 should be attainable in the warm
sector, as dew points climb to near 70, resulting in late afternoon
MUCAPE of 2000-2500 J/kg.
Another wave approaches the area from the southwest Monday evening,
accompanied by a 90+ kt jet streak, which will provide stronger
forcing and shear needed to develop and sustain strong to severe
storms. Given timing near 00Z, and decent capping inversion seen on
forecast soundings, window for surface based storms is short, but if
storms are able to develop along the warm front, cannot rule out an
isolated tornado threat early in the evening. Otherwise steep mid
level lapse rates and moderate-strong shear will support potential
for large hail/damaging winds from isolated to scattered storms
through the early-mid evening. Threat should then transition to
strong winds and locally heavy rain as increasing southwesterly low
level jet could result in backbuilding/training storms.
Evolution for Tuesday/Tuesday night more unclear, as uncertainties
abound regarding how much convection/cloud cover will linger across
the area through the day, and where any boundaries resulting from
Monday night`s convection will eventually end up. Tuesday daytime
hours could end up being a little drier at times than currently
indicated in the forecast, as region could again be between upper
level waves. However, deeper moisture still supports ample cloud
cover, and overall looking at cooler temperatures in the 70s to
lower 80s. This could limit extent of severe development, but with
sharp low level boundary in the vicinity, strong shear and modest
instability, potential for isolated severe storms certainly there.
This boundary will be focus for what appears to be greater threat of
locally heavy rain again developing Tuesday night. Current consensus
places areas near/south of KYKN-KMJQ line in more favorable location
for this, but again that could shift depending on where the boundary
ends up.
Approach of stronger upper trough should pull the boundary back to
the northwest on Wednesday, keeping moderate storm chances and an
isolated severe threat around until the trough moves off to our east
Wednesday evening. Remainder of the forecast period looks to dry out
a bit, except for one more shot at rain Thursday night and Friday as
another trough swings through the northern Plains. Mid to late week
looks to remain on the cooler side as well, with highs generally in
the 70s
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1028 PM CDT Sat Sep 3 2016
Scattered showers and isolated thunderstorms will move northeast
through northwest Iowa, far southeast South Dakota and southwest
Minnesota through early morning. Areas west of Interstate 29 will
see a good chance for MVFR ceilings to develop and these should
remain in place through about mid to late Sunday morning.
Otherwise thunderstorms will again be possible after about 22z
with the better chances west of Interstate 29 and north of
Interstate 90.
&&
.FSD Watches/Warnings/Advisories...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
SHORT TERM...
LONG TERM...JH
AVIATION...08
Area Forecast Discussion
National Weather Service Goodland KS
302 AM MDT SUN SEP 4 2016
.SHORT TERM...(Today through Tuesday Night)
Issued at 302 AM MDT Sun Sep 4 2016
Early morning WV imagery and RAP upper level analysis show SW flow
across the Central High Plains, with a shortwave trough over south
central Nebraska and north central Kansas. A weakening thunderstorm
cluster associated with this shortwave trough is exiting our CWA to
the east. At the surface Low pressure is in place near the CO/KS
border, with a surface trough axis extending along the I-70
corridor.
Today-Tonight: Guidance shows another shortwave trough moving across
our CWA by the afternoon/evening. Anomalously high PWATs remain in
place, and with instability increasing once again to at least
moderate levels we could see the potential for heavy rain and flash
flooding. Deep layer shear also remains favorable for organized
activity with either supercells or thunderstorm clusters/complexes
possible. As Better forcing may remain further north, activity may
remain isolated and coverage is not certain. At the same time
convective allowing guidance indicates isolated to scattered
activity once again merging into clusters that would track to the
northeast over similar locations that received heavy rain.
The flash flood watch for the morning will likely be allowed to
expire once ongoing activity ends this morning. A flash flood watch
will likely be issued for the afternoon/evening to cover potential
with thunderstorms that redevelop during those periods. Will hold
off until current watch is cleared before re issuance to avoid
confusion.
Monday-Tuesday Night: SW flow remains in place and passing shortwave
troughs will continue to bring occasional thunderstorm chances to
parts of the region. A front is shown to move into or through our
CWA Tuesday or Tuesday night (depending on model) and could bring
better chances/coverage and model consensus is favoring these
periods (particularly Tuesday night).
Regarding temperatures: Highs and Lows will trend upwards through
Monday due to increasing WAA in SW flow through Monday. Due to FROPA
Tuesday we should see highs trend downwards from the NW to SE as
reflected in latest model means/blends.
.LONG TERM...(Wednesday through Saturday)
Issued at 228 AM MDT Sun Sep 4 2016
The first half of the extended period will be dry. This is due to a
trough that is moving east out of the region. Then a zonal flow
dominates over the CWA. Come Friday, another trough moves over the
region and brings with it a cold front. This front and trough will
be most impactful, precipitation wise, in the eastern portions of
the CWA. Saturday has some lingering precipitation chances in the
southern counties of the CWA with the exiting trough and front.
Models are showing a strong ridge developing in the western CONUS,
so dry and warmer conditions could be possible after the period.
Temperatures will be in the mid 80s to low 90s for the first half of
the period and then temperatures will drop into the 70s for the
second half due to the passage of the cold front.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1107 PM MDT Sat Sep 3 2016
For KGLD...Mainly VFR w/ scattered low/mid clouds. MVFR fog
possible 09z-13z to 3sm at times. VCSH after 22z Sunday. Winds SSW
15-25kts.
For KMCK...Mainly VFR w/ scattered cloud cover. 06z-08z MVFR/IFR
conditions with trw w/ visibility down to 1 1/2sm at times and
ceilings to ovc025. IFR fog 09z- 13z down to 2sm at times.. VCSH
after 21z Sunday. Winds SSE 15-25kts.
&&
.GLD Watches/Warnings/Advisories...
KS...Flash Flood Watch until 6 AM MDT /7 AM CDT/ early this morning
for KSZ001>004-013>016-029.
CO...NONE.
NE...Flash Flood Watch until 6 AM MDT /7 AM CDT/ early this morning
for NEZ079>081.
&&
$$
SHORT TERM...DR
LONG TERM...CLT
AVIATION...JN
AREA FORECAST DISCUSSION
National Weather Service New Orleans LA
348 AM CDT SUN SEP 4 2016
.SHORT TERM...
A weak frontal boundary that had stalled across southern portions of
the forecast area has all but completely dispersed. This is
evident by surface observations that show lower to mid 70
dewpoints areawide with slightly higher numbers offshore. Surface
ridge centered well northeast of the area will build south and
west into the Gulf of Mexico and across Louisiana which will
cause southeast winds to develop and strengthen. The HRRR suggests
convection will initiate in the coastal warm sector this morning
and shift northward across the rest of the CWA late morning and
into the afternoon. Considering how the HRRR embarrassed medium
range models, especially the ECMWF, in terms its ability to
correctly forecast thunderstorm placement and timing yesterday,
the pop forecast today is heavily weighted on that model. The GFS
output for today is considered more of a supporting output, but
not much different than the HRRR. Model soundings once again show
an inverted-V with dry air aloft which would suggest the potential
for microbursts. A few storms could produce damaging winds in the
strong to maybe severe range. High temps are at or slightly above
guidance although areas south of Lake Pontchartrain may not get
higher than mid/upper 80s as T-Storm development could limit daily
warming.
Labor day will be much like today as a maritime upper level ridge
builds over the gulf south. This will continue to enhance moisture
return to the whole forecast area and subsequently higher chance for
rainfall. Expect a typical diurnal pattern with convection
initiating late morning and thunderstorms carrying over into the
afternoon and early evening hours. Overall pops should fall in the
50 to 60% range which is similar to the previous forecast.
.LONG TERM...
The maritime ridge will begin to take on more continental
characteristics as it expands north and eastward midweek. This will
draw in drier air to the region from the northeast. That along
with increased subsidence will hinder daily thunderstorm
development for all but offshore locations with the caveat that
areas along the western fringe of the CWA could see isolated
storms. How long the ridge holds strong will determine how long of
generally dry period will remain in place.
MEFFER
&&
.AVIATION...
Most terminals should receive at least one ts today. TEMPO groups
should suffice for the most part while a few coastal locations may
even see prevailing for several hours. Should be able to show most
with prevailing VCTS by late morning. Obviously IFR conditions
within ts expected while outside of activity VFR expected.
Convective activity to dissipate overnight and back again Monday.
&&
.MARINE...
light winds and low seas are expected the next 5 days with only
concerns being near convection where gusts around 25 knots,
occasional lightning and isolated waterspouts will be the norm each
day. 24/RR
&&
.DECISION SUPPORT...
DSS code: Green.
Deployed: None.
Activation: None.
Activities: None.
Decision Support Services (DSS) Code Legend
Green = No weather impacts that require action.
Blue = Long-fused watch, warning, or advisory in effect or
high visibility event.
Yellow = Heightened impacts with short-fused watch, warning
or advisory issuances; radar support.
Orange = High Impacts; Slight to Moderate risk severe; nearby
tropical events; HazMat or other large episodes.
Red = Full engagement for Moderate risk of severe and/or
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 91 72 90 73 / 40 20 50 20
BTR 92 74 90 73 / 50 20 50 20
ASD 90 75 90 75 / 50 20 50 20
MSY 88 80 91 80 / 50 30 50 20
GPT 89 76 88 76 / 50 20 50 20
PQL 89 75 88 75 / 60 30 50 20
&&
.LIX Watches/Warnings/Advisories...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
505 AM EDT SUN SEP 4 2016
.SHORT TERM...(Today and tonight)
Issued at 503 AM EDT SUN SEP 4 2016
WV imagery and RAP analysis indicated sw mid/upper level flow from
the srn Rockies to the upper MS valley between a ridge over the
cntrl Great Lakes and a trough into the wrn CONUS. At the surface,
srly winds were also increasing through the upper MS valley between
high pres over the ern Great Lakes and a trough over the cntrl
Dakotas.
Today, with only a slow progression to the pattern srly winds will
continue to bring relatively dry air into Upper Michigan resulting
in mostly sunny skies. With 850 mb temps around 12C-13C, similar to
Saturday, expect max temps again in the upper 70s to around 80.
Tonight, the combination of a shrtwv trough moving from the Dakotas
to ne MN and strong theta-e advection with 40 knot sw 850 mb winds,
will support shra/tsra into wrn Lake Superior and possibly into wrn
Upper Michigan late tonight. since the pcpn will be moving into the
dry airmass over the region, the forecast maintains only chance
pops, mainly for the far west near Ironwood and Ontonagon.
Forecast MUCAPE values to around 500 J/Kg will limit TS strength.
Breezy south winds will keep temps from dropping off with min
readings in the upper 50s to the mid 60s, warmest where downslope
flow prevails near Lake Superior.
.LONG TERM...(Monday through Saturday)
Issued at 501 AM EDT SUN SEP 4 2016
A shortwave lifting ne through the Upper MS River Valley could bring
some showers/TS to western Upper Mi on Labor Day, but otherwise
broad sfc high pressure moving only slowly to the e combined with
mid level dry air under a high amplitude upper ridge will maintain
dry and warm weather across the forecast area thru Labor Day. As the
upper ridge flattens toward mid week and a slow moving cold front
crosses the area under a very moist airmass, shower/TS chances will
be on the increase later on Tue into Thu. Although the details are
still far fm certain, there could be some heavy rain during this
time over at least a portion of Upper MI. The period into Tue wl be
a warm one, but cooler wx should arrive for later in the week behind
the slow cold fropa.
Labor Day...Persistent higher heights/mid level dry air over Upr MI
should result in continued dry wx for at least the majority of the
cwa on Labor Day. Model guidance does show a shortwave lifting NE
thru MN. Accompanying dpva/weak deep layer q-vector convergence are
fcst to impact the western cwa and could bring some sct shra/tsra
into mainly the western portion of Upper MI. But given the fcst weak
height falls and fairly weak forcing fm the shortwave through a
relatively dry/stable mid level antecedent airmass, wl tend to favor
the drier end of the guidance. As a result, wl continue chc pops
western cwa for Labor Day with highest chc pops closer to Isle
Royale and closer to track of shortwave where deeper moisture and
better shortwave dynamics exist. Even if there are more clouds on
Labor Day especially over the W, h85 temps peaking at 17-18C wl
support max temps into the 80s away fm Lake Mi moderation. Pwats
rising to near 1.5 inches and dewpoints climbing into the lower to
mid 60s will also make for much more uncomfortably humid conditions.
Mon ngt/Tue night...Models indicate one shrtwv and assoc sfc wave
lifting NE thru the Dakotas/Mn Mon night into Tue morning with weak
dynamics fm shortwave again brushing the NW half of the cwa. A
similar absence of significant height falls associated with the
shortwave and continued persistent upper ridging wl tend to maintain
a more capped environment and may inhibit convection Mon night into
Tue morning even over the NW half where models show the slow-moving
cold front approaching fm the west. Models then indicate a second
shortwave riding over the frontal boundary as it moves into the
western half of Upper Mi Tue afternoon so for this reason wl
maintain going likely pops Tue afternoon across much of the forecast
area. If cap can be broken with shortwave, there is enough
instability as MUCAPEs rise to 1000-1500 j/kg and effective shear to
near 30 knots to maybe produce an isolated strong to marginally
severe storm Tue afternoon into Tue evening. Warm and humid
conditions wl prevail under deep SW flow that maintains higher pwats
in the 1.5-2.0 inch range. Expect min temps on Mon night to hold in
the 65-70F range under the tighter pres gradient/and mixing fm
stronger h925 SW winds up to near 35 kts per fcst soundings. High
temps on Tue should climb into the 80s, at least away fm Lake
Michigan moderation and the far W, where there wl likely be more
clouds associated with the weak cold fropa.
Wednesday through Sunday...Longer range models continue to show
gradual height falls over the Upper Lakes by mid week as the upper
ridge axis tends to flatten out and push east with the advance of
persistent upper troffing over western North America. Since the
passing sfc cold front wl be nearly parallel to the SW flow aloft,
models continue to show only slow progress with this frontal boundary
through the Upper Great Lakes region. There are still plenty of model
differences with the progress/placement of the front as well as on
the timing/track of a series of shortwaves and accompanying sfc low
pres waves fcst to move along the front. Nonetheless, this setup
along with fcst pwat up to 2 inches should bring the potential for
heavy rains to at least part of the cwa with model guidance
indicating Wed into Thu morning as best opportunity. This is also
consistent with the NCEP Day 3-7 Hazards Outlook which indicates
heavy rain potential for Wed into Thu. Most of the extended models
indicate a general break in the pcpn later Thu afternoon into Fri
with the hint of shortwave rdgg/mid lvl dry air and assoc sfc rdgg
into the area. At the same time, the persistent WSW flow aloft ahead
of mean troffing over the Rockies/Northern Plains could keep the
front close enough to allow upper disturbances to influence the area.
Models advertise the main mid-upper level trof moving in from the
Northern Plains Fri night and Sat along with a sfc trof/cold frontal
boundary and this will warrant higher chc pops for the Fri night into
Sat time frame. Although Tue night/Wed should still feature aoa
normal temps, cooler wx, especially daytime max temps, should
dominate toward the weekend as the mid-upper level trof moves in from
the Northern Plains and pulls in colder air behind the secondary cold
frontal passage.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 124 AM EDT SUN SEP 4 2016
Expect VFR conditions at all 3 TAF sites this fcst period as the
incrsg S flow arnd hi pres moving toward New England continues to
tap dry air. The S winds just above the nocturnal invrn early this
mrng may aprch LLWS criteria at IWD, but looks like the shear is not
sufficient to include LLWS in the fcst attm. With daytime heating/
mixing on Sun, included some gusty S winds in the fcst for the more
exposed IWD and SAW locations. These gusty winds wl dimininsh this
evng with the loss of mixing after sunset. With an even sharper pres
gradient dvlpg tngt, did include LLWS late in the fcst at IWD where
the gradient wl be tightest.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 503 AM EDT SUN SEP 4 2016
Winds through the middle of next week are expected to remain at 20
kts or less. The only exception would be on Monday as south to
southwest winds may push above 20 kts in gusts over eastern Lake
Superior ahead of an approaching low pressure trough. Low pressure
crossing Lake Superior next weekend may result in westerly winds to
30kts across the Lake Superior depending on the exact track of the
low.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Voss
AVIATION...KC
MARINE...JLB
Area Forecast Discussion
National Weather Service Pueblo CO
1115 PM MDT SAT SEP 3 2016
.SHORT TERM...(This evening through Sunday)
Issued at 220 PM MDT Sat Sep 3 2016
This early afternoon some isold showers and thunderstorms had
developed from around the I-25 corridor and Palmer Dvd and westward.
A weak disturbance wl continue moving through east central and
northeast CO this afternoon and evening. Although there wl be the
possibility of isold storms ovr much of the area this evening, the
best chances wl be ovr northern portions of the forecast area, from
the central CO mtns, acrs Teller and El Paso counties and eastward.
Radar at 140 pm was showing a line of convection from north of Limon
to northeast El Paso county. The HRRR continues to show a line of
convection ovr northeast and east central CO this afternoon and
early this evening, then moving into northwest KS. This line of
convection may brush Kiowa county and could bring some heavy rain.
The latest meso analysis is showing 2000+ J/kg of CAPE ovr east
central CO and ovr the far sern corner of CO. The NAM forecast for
late this afternoon/early this evening has 0-6 km bulk shear values
of 40-50 kts ovr Kiowa county. If the convection does moves thru the
far eastern portions of the sern plains, there will be the
possibility of some severe weather, with large hail and damaging
winds being the main threats.
By late evening chances for thunderstorms will mostly end, however
locations near the KS border may see some lingering convection until
around midnight, and there could be some isolated showers or tstms
thru the night and into Sun morning along the Continental Divide.
Drier conditions are then expected on Sun, with little chance for
pcpn, but there could be a few shower/storms ovr the hyr trrn. With
an upper level trof being ovr the western U.S., the flow aloft ovr
the area will be southwesterly. At the surface, breezy south to
southwest winds can be expected, especially in the afternoon and
early evening hours. High temps on Sun are expected to be a little
above average acrs the southeast plains, and around average in the
high valleys.
.LONG TERM...(Sunday night through Saturday)
Issued at 220 PM MDT Sat Sep 3 2016
...Dry and warm week ahead...
A trough will slowly progress eastward this coming week, moving
from the great basin early on Monday to the Rockies by mid-week,
then on to the Mississippi Valley late in the week. This will
bring and extended period of dry and very warm weather.
Temperatures during this time will run from 5 to 10 degrees above
average over the Plains. Will see highs in the lower 90s for the
first half of the week as southwesterly flow persists over our
area. On Monday and Tuesday, some moisture will be drawn up from
the south as southerly flow increases over our area. This will
bring a slight chance of convection, mainly over southern portions
of our CWA. A couple of storms out over the Plains could be on the
strong to severe side given the increased winds aloft and
corresponding increase in bulk shears. Tuesday afternoon-eve looks
like the best bet for any svr at this time.
By the latter part of the week, the upper low will eject
northeastward into E Canada and SW flow will transition to
Westerly and finally Northwesterly by next week`s end, and this
will tend to bring continued breezy, warm, and dry conditions to
our area. It probably wont be until late next weekend or early the
following week that we see a return of any significant moisture.
Rose
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 1112 PM MDT Sat Sep 3 2016
VFR conditions are anticipated during the next 24h at all 3 taf
sites...kpub...kcos and kals.
Winds are going to get gusty by late morning/early afternoon at
each taf site. Generally southwest winds of 15 to 30 knts will
develop. These winds will decrease by early evening.
&&
.PUB Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...28
LONG TERM...ROSE
AVIATION...HODANISH
Area Forecast Discussion
National Weather Service Blacksburg VA
259 AM EDT Sun Sep 4 2016
.SYNOPSIS...
T.S. Hermine will linger off the Mid-Atlantic coast through the
mid part of the week. Meanwhile, high pressure aloft will build
to the west of the tropical storm over the Appalachians and Ohio
Valley. The tropical cyclone and the high pressure area will
finally give way to a cold front late in the week, which will
bring the next chance significant chance of rain to the region.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 245 AM EDT Sunday...
As T.S. Hermine lingers and meanders off the Delmarva Peninsula, a
weak east-west elongated area of low pressure will drift south
across the region. This will bring bkn-ovc mid/high clouds and a
few sprinkles, possibly a few light rain showers, to the region
from north to south over the next 12 hours, mainly east of the
Alleghany front. Expect this feature to drift into southwest
VA/northwest NC by Sunday afternoon and dissipate. Occasional
spiral bands of moisture may still drift across areas east of the
Blue Ridge through the remainder of the forecast period.
Otherwise, mainly a dry forecast. Have included some 14-15% pops
for RW or RW-- (sprinkles) from north to southwest over the first
12 hours.
850mb temperatures show very little change through the period.
This combined with variable cloud cover should yield maximum
temperatures Sunday afternoon very similar to what was observed
Saturday. Minimum temperatures will start to creep upward a few
degrees each day as the high builds over the region, but dewpoints
are expected to remain in the upper 50s to lower 60s through the
near term.
The wind circulation around Hermine will not be a factor any
longer, at least in terms of speed. Areas east of the Blue Ridge
will continue to favor a North-Northeast wind for a few days,
however, as a result of the proximity of T.S. Hermine.
&&
.SHORT TERM /MONDAY THROUGH WEDNESDAY NIGHT/...
As of 330 AM EDT Sunday...
Things are still looking quiet through the first part of the workweek.
Hermine is expected to do a sit/and/spin off the middle Atlantic coast
for the next few days, which will keep us locked into a blocky pattern
with dry high pressure surface and aloft. The most notable feature of
our weather through midweek will be a gradual warming trend that will
bring us above normal temperatures by Wednesday with highs ranging from
the lower 90s east of the Blue Ridge to the mid/upper 80s west.
Thankfully moisture return will be slow and the airmass will remain
relatively dry and we will avoid the oppressive humidity for now. The
dry conditions will also allow us to cool nicely at night and some of
the cooler valleys west of the Blue Ridge may well see lows dipping
into the 40s for the next several days.
&&
.LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 200 PM EDT Saturday...
Hermine progged to meander off the Mid-Atlantic coast through at least
mid week before finally booting east ahead of the next upstream 500 mb
trough that will approach late in the week. This should again keep a
dry northerly flow in place early in the period under increased
subsidence as heights build ahead of ridging aloft sliding in from the
west. Flow should become more zonal later in the week into early next
weekend in response to gradual digging of northern stream energy that
will tend to flatten high heights across the region. This should also
allow for a gradual return of low level moisture by Friday ahead of a
weak front to the north and a stronger upstream cold front on Saturday.
Appears enough moisture with orographics and heating to support
mainly diurnal chance pops west Friday and perhaps a little better
coverage Saturday. Otherwise will remain quite warm for early
September under very warm 850 mb temps and plenty of sun for most
of the period. Latest blend supports highs mid/upper 80s mountains
to low/mid 90s east, with a gradual increase in humidity through
Saturday.
&&
.AVIATION /07Z SUNDAY THROUGH THURSDAY/...
As of 140 AM EDT Sunday...
A VFR forecast expected through the period, but it will not be
SKC. T.S. Hermine continues to linger off the Delmarva coast and
will likely do so for several days. A chaotic upper air pattern
is in place across the Mid-Atlantic into the Ohio Valley which
involves T.S. Hermine, an upper low over the top of Hermine, and
high pressure aloft building across the OH Valley. A notable lobe
of PVA was evident across northern VA/WV that will rotate with the
upper low south-southwest overnight into Sunday. Mainly this
feature will bring an area of fairly extensive mid-high clouds
across the region from the north through the night, translating
into southwest VA/northwest NC by mid-day Sunday, which it will
begin to dissipate as it moves away from its source region. Cannot
totally rule out a few sprinkles with this feature as was the case
Saturday evening. Latest regional radar indeed shows virga and
some light rain north of the I-66 corridor working its way down
toward the I-64 corridor. The GFS, NAM, and HRRR have the best
handle on this. Not enough confidence to include any precipitation
in the TAFs. All associated cloud bases are expected to be 050 or
greater, mostly in the 080-150 range. After 18Z Sunday, expect
conditions to trend more toward SKC with just some scattered
mid/high clouds left. With Hermine just off the Delmarva and
perhaps intensifying with time, as well as the upper low in the
vicinity, it will be hard to get SKC.
Fog development is not expected due to aforementioned clouds.
Hermine has moved far enough away to allow the wind field to
relax. West of the Blue Ridge, winds have become light and
variable. East of the Blue Ridge, there is still a tendency to
lean toward a NE direction. Expect this pattern to continue into
Sunday with no gusts and sustained speeds generally 7kts or less.
Medium to high confidence in cigs throughout the TAF valid period.
High confidence in VFR vsbys throughout the TAF valid period.
Medium confidence in wind direction and speed throughout the TAF
valid period.
Extended aviation discussion...
Generally VFR conditions expected through much of the extended
period as Hermine lingers off the mid-Atlantic coast for several
days into the mid part of next week. There may be some mid/high
clouds at times, otherwise VFR. This will put our area in a
subsidence zone for several days. Early morning/late night fog
development may evolve toward the mid and later part of the week as
low-level moisture slowly increases, but very little expected
through the early part of next week.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...RAB
NEAR TERM...RAB
SHORT TERM...MBS
LONG TERM...JH
AVIATION...RAB
Area Forecast Discussion
National Weather Service Bismarck ND
908 AM CDT SUN SEP 4 2016
.UPDATE...
Issued at 905 AM CDT Sun Sep 4 2016
Showers and thunderstorms continue to develop over the area, with
the strongest storms now in the vicinity of the frontal boundary
stretching from near Carrington to the southwest. Expect this will
remain the focus for the severe potential, though a strong post-
frontal storm does not remain out of the question as we had a few
earlier this morning. One continues to produce gusty winds sliding
through Sheridan and Wells Counties at this time. Updates have
been sent.
UPDATE Issued at 602 AM CDT Sun Sep 4 2016
Very dynamic and active morning across the region. Several
thunderstorms have grown to severe limits based on radar imagery
along the frontal boundary in northeast North Dakota early this
morning. Now more thunderstorms are forming across south central
North Dakota and latest HRRR has a strong line/bow echo beginning
southwest and tracking northeast. Used the latest HRRR pop
initialization. Moved the threat for severe weather up to this
morning.
&&
.SHORT TERM...(Today and tonight)
Issued at 329 AM CDT Sun Sep 4 2016
A significant jet streak at h300 is forecast to move northeast
from the four corners region into the upper plains today and
tonight. Co-incident with this, a northern stream 100+ kt jet is
over topping a broad ridge across southern Canada creating
significant diffluence aloft between the two features. This will
act in tandem to create a large and persistent upward motion field
across North Dakota and in turn increase the low level jet
pulling moisture into the region. Other important factors such as
a two standard deviation from normal precipitable water anomaly
will support wide spread showers and thunderstorms across the
state today and tonight.
The first push of precipitation is moving into southwest north
dakota this morning. Now finally seeing the expected line of
storms forming in northeast North Dakota along the frontal
boundary. This makes the pop forecast a bit complex early today
but by late morning widespread showers and thunderstorms will
connect from the southwest into the northeast. Have adjusted pops
per the latest HRRR runs for the morning hours.
The front will also be the focus for severe thunderstorms this
afternoon and evening. Current thinking is sufficient heating will
allow the cape to reach the forecast 1500-2500 the models suggest.
For this afternoon and evening a slight risk of severe thunderstorms
are noted.
Moderate to heavy rain will be the result across the James river
valley later today and tonight. Local amounts of 3 inches or a
little more will extend over sufficiently long 6 to 12 hour period
and at this time flash flooding is not anticipated. Will not issue
any headlines for this.
.LONG TERM...(Monday through Saturday)
Issued at 329 AM CDT Sun Sep 4 2016
The long term continues to look cooler and active as a broad
cyclonic flow will remain over the northern plains with several
shortwaves moving through. The superblend guidance indicated the
best chance for showers this coming week will be wednesday with a
transient short wave producing likely pops. There will be at
least a chance for showers and thunderstorms through Saturday.
Highs Monday will be the coolest with upper 50s northwest and the
60s east. Then highs will be in the 60s to lower 70s for the
remainder of the week.
&&
.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 602 AM CDT Sun Sep 4 2016
Showers and thunderstorms will impact the area through the
day. The best chance for thunderstorms will be at KDIK, KBIS, and
KJMS this morning and early afternoon. Another round of
thunderstorms will be possible mid afternoon Sunday at KJMS. MVFR
cigs with localized IFR cigs will develop along with the potential
for reduced visibilities in precipiation.
&&
.BIS Watches/Warnings/Advisories...
NONE.
&&
$$
UPDATE...JJS
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...MM
Area Forecast Discussion
National Weather Service Kansas City/Pleasant Hill MO
630 AM CDT SUN SEP 4 2016
.Discussion...
Issued at 344 AM CDT SUN SEP 4 2016
Short Range:
The surface high pressure system which kept us nice and comfy with
mild days, cool nights and pleasant humidities is slowly loosing its
influence on our weather. Surface winds have veered to the southeast
and will eventually swing around to south and south-southwest next
week.
For today we have a little fly in the ointment. A shrinking MCS over
southern NE/northern KS will work its way east this morning with rain
chances on tap for northwest MO and parts of west central MO.
Satellite trends show a slow cloud top warming indicating gradually
weakening convection, supporting a path the HRRR has been trending
towards all night. So, will weaken the convection as it moves into
northwest MO. How fast the convective debris/cloud cover dissipate is
open for debate. Should the cloud cover be slow to burn off the day
shift will need to lower max temperatures. For now will play it
conservatively and trim high temperatures by a degree or two over
northern MO.
Next Week:
For the past few days we`ve talked about how post-Tropical Cyclone
Hermine, spinning basically in the same location off the northern Mid
Atlantic Coast, would act as a block...and effectively keep our
weather in a holding pattern through Wednesday. The latest rendition
of the operational models hasn`t changed much since Friday. We
anticipate an upper level ridge to our east allowing southwesterly
flow aloft to draw layered moisture northeast. In addition there
will likely be an embedded weak upper trough or two which will
generate scattered convection over the Central Plains and eventually
spreading into the CWA. Timing seems to favor Wednesday with the
arrival of the first batch of convection. Even higher PoPs are
expected Thursday through Friday night when an upper level trough
finally moves across the north central U.S. and sends a frontal
boundary southward. Difficult this far out to determine if the front
stalls out in the CWA or north in IA as the front will run nearly
parallel to the mid/upper level flow. Overall, expect a couple
periods of showers and storms and a return to above normal
temperatures and yucky humidity.
&&
.Aviation...(For the 12Z TAFS through 12Z Monday Morning)
Issued at 628 AM CDT SUN SEP 4 2016
A shrinking complex of thunderstorms over northeast KS will dissipate
as it enters and moves through far northwest MO this morning.
Ceilings should remain VFR. Otherwise, VFR conditions expected with
the convective cloud debris likely thinning out/dissipating across
northern MO by early afternoon.
&&
.EAX Watches/Warnings/Advisories...
KS...None.
MO...None.
&&
$$
Discussion...MJ
Aviation...MJ
Area Forecast Discussion
National Weather Service Sioux Falls SD
639 AM CDT SUN SEP 4 2016
.SHORT TERM...(Today and Tonight)
Issued at 425 AM CDT Sun Sep 4 2016
Plenty of questions on shower and storm coverage for today, with
initial early morning convection over the southeast half of the
area, roughly Brookings to Yankton area and southeast. Despite
continuing feed of moist and increasingly unstable air, the
temporary fading of the low level jet, and the pulling northeast of
a distinct short wave lobe shown on models suggest a decrease of
activity in this area later this morning into early afternoon, and
that is what we will go with for now. With MUCAPE increasing slowly
toward 2000 j/kg, storms are getting a little stronger this morning
but do not see a severe risk, yet anyway.
Expect clouds to decrease from the west through early afternoon and
some heating to set in. The big question is whether or not there
will be redevelopment of storms in the mid to late afternoon over
the same southeast half of the area, as the experimental HRRR is
starting to suggest, albeit in fairly modest coverage. Given the
approach of strong support from the west late in the day, I feel
that the redevelopment in the southeast is overdone.
Temperatures will warm a bit stubbornly into the upper 70s to lower
80s east of the James River this afternoon, and into the mid to
possible upper 80s west. Southerly/southeasterly surface winds will
again increase to the windy category but should stay short of wind
advisory levels/
This brings us to tonight and the obvious potential of widespread,
and possibly severe, showers and storms moving east across the
area, especially north. POPs will be likely to unqualified west and
north for tonight, with a decent chance south and southeast of FSD.
This seems reasonable, given the northeast movement of the upper
support, and the location of the surface front on the northwest end
of the area.
The SPC severe risk looks good, with the greater risk over southeast
SD and possibly into part of southwest MN. decent 2000-3000 j/kg
CAPE and favorable low to mid level wind fields will couple with the
upper support and good low level jet. The severe threat should fade
after the evening hours.
Loaded QPF is probably good with a widespread half inch plus of rain
tonight from FSD north and west, but there will surely be some areas
over an inch. Locally even higher amounts look possible, but given
the dry conditions lately, and the likely decent cell movement, feel
local flooding is unlikely.
.LONG TERM...(Monday through Saturday)
Issued at 425 AM CDT Sun Sep 4 2016
Active pattern will continue through much of the work week, though
latter half does show some promise for more sporadic precip chances
than do the first few days.
Labor Day could begin with isolated storms lingering in northwest
Iowa/southwest Minnesota just after daybreak, though anticipate any
activity to push east of the area/diminish by mid morning. Models
showing fairly good agreement in placing surface front from central
Nebraska/south central South Dakota, into northeast South Dakota and
northwest Minnesota early. Boundary remains nearly stationary as a
surface wave slides northeast along the front, reaching east central
South Dakota by late afternoon, with more well-defined warm front
developing just north of Highway 14 and cold front from near Huron
southward into central Nebraska. Despite what could be slightly
subsident air mass in the wake of mid level wave lifting into the
Red River Valley Monday afternoon, low level support from the
approaching surface wave warrants maintaining low pops along and
north/west of the surface boundary. Models showing fair amount of
moisture persisting below 700mb, so concerned that cloud cover could
be a little more persistent during the day and inhibit heating, and
GFS/NAM continue to be overdoing the mixing. But highs closer to the
ECMWF in the mid 80s to near 90 should be attainable in the warm
sector, as dew points climb to near 70, resulting in late afternoon
MUCAPE of 2000-2500 J/kg.
Another wave approaches the area from the southwest Monday evening,
accompanied by a 90+ kt jet streak, which will provide stronger
forcing and shear needed to develop and sustain strong to severe
storms. Given timing near 00Z, and decent capping inversion seen on
forecast soundings, window for surface based storms is short, but if
storms are able to develop along the warm front, cannot rule out an
isolated tornado threat early in the evening. Otherwise steep mid
level lapse rates and moderate-strong shear will support potential
for large hail/damaging winds from isolated to scattered storms
through the early-mid evening. Threat should then transition to
strong winds and locally heavy rain as increasing southwesterly low
level jet could result in backbuilding/training storms.
Evolution for Tuesday/Tuesday night more unclear, as uncertainties
abound regarding how much convection/cloud cover will linger across
the area through the day, and where any boundaries resulting from
Monday night`s convection will eventually end up. Tuesday daytime
hours could end up being a little drier at times than currently
indicated in the forecast, as region could again be between upper
level waves. However, deeper moisture still supports ample cloud
cover, and overall looking at cooler temperatures in the 70s to
lower 80s. This could limit extent of severe development, but with
sharp low level boundary in the vicinity, strong shear and modest
instability, potential for isolated severe storms certainly there.
This boundary will be focus for what appears to be greater threat of
locally heavy rain again developing Tuesday night. Current consensus
places areas near/south of KYKN-KMJQ line in more favorable location
for this, but again that could shift depending on where the boundary
ends up.
Approach of stronger upper trough should pull the boundary back to
the northwest on Wednesday, keeping moderate storm chances and an
isolated severe threat around until the trough moves off to our east
Wednesday evening. Remainder of the forecast period looks to dry out
a bit, except for one more shot at rain Thursday night and Friday as
another trough swings through the northern Plains. Mid to late week
looks to remain on the cooler side as well, with highs generally in
the 70s
&&
.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 639 AM CDT Sun Sep 4 2016
Scattered SHRA/TSRA BKX/FSD/YKN and east through 04/18z. Scattered
to numerous TSRA developing HON/9V9 around 04/23z and spreading
east over the area through 05/08Z with local 3-5SM and ceilings
2-4k feet. Outside of SHRA/TSRA VFR except until 04/18z ceilings
1-3k feet in a small area south of 9v9. Surface gusts 25-30 knots
from the south over the area through 05/03z.
&&
.FSD Watches/Warnings/Advisories...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
SHORT TERM...
LONG TERM...JH
AVIATION...
Area Forecast Discussion
National Weather Service Goodland KS
530 AM MDT SUN SEP 4 2016
.UPDATE...
Issued at 530 AM MDT Sun Sep 4 2016
Cancelled flash flood watch for the morning period earlier, and
issued new flash flood watch for the afternoon and evening.
Coverage could still be in question, but high resolution guidance
continues to show potential for scattered to numerous storms
moving over areas that recently received heavy rainfall and flash
flooding. Considering the moist nature of the air mass even
isolated thunderstorms may be capable of producing localizedflash
flooding. Rather than get too specific I extended the watch to
include most areas that current guidance has favored for potential
convective activity during the watch period.
&&
.SHORT TERM...(Today through Tuesday Night)
Issued at 302 AM MDT Sun Sep 4 2016
Early morning WV imagery and RAP upper level analysis show SW flow
across the Central High Plains, with a shortwave trough over south
central Nebraska and north central Kansas. A weakening thunderstorm
cluster associated with this shortwave trough is exiting our CWA to
the east. At the surface Low pressure is in place near the CO/KS
border, with a surface trough axis extending along the I-70
corridor.
Today-Tonight: Guidance shows another shortwave trough moving across
our CWA by the afternoon/evening. Anomalously high PWATs remain in
place, and with instability increasing once again to at least
moderate levels we could see the potential for heavy rain and flash
flooding. Deep layer shear also remains favorable for organized
activity with either supercells or thunderstorm clusters/complexes
possible. As Better forcing may remain further north, activity may
remain isolated and coverage is not certain. At the same time
convective allowing guidance indicates isolated to scattered
activity once again merging into clusters that would track to the
northeast over similar locations that received heavy rain.
The flash flood watch for the morning will likely be allowed to
expire once ongoing activity ends this morning. A flash flood watch
will likely be issued for the afternoon/evening to cover potential
with thunderstorms that redevelop during those periods. Will hold
off until current watch is cleared before re issuance to avoid
confusion.
Monday-Tuesday Night: SW flow remains in place and passing shortwave
troughs will continue to bring occasional thunderstorm chances to
parts of the region. A front is shown to move into or through our
CWA Tuesday or Tuesday night (depending on model) and could bring
better chances/coverage and model consensus is favoring these
periods (particularly Tuesday night).
Regarding temperatures: Highs and Lows will trend upwards through
Monday due to increasing WAA in SW flow through Monday. Due to FROPA
Tuesday we should see highs trend downwards from the NW to SE as
reflected in latest model means/blends.
.LONG TERM...(Wednesday through Saturday)
Issued at 228 AM MDT Sun Sep 4 2016
The first half of the extended period will be dry. This is due to a
trough that is moving east out of the region. Then a zonal flow
dominates over the CWA. Come Friday, another trough moves over the
region and brings with it a cold front. This front and trough will
be most impactful, precipitation wise, in the eastern portions of
the CWA. Saturday has some lingering precipitation chances in the
southern counties of the CWA with the exiting trough and front.
Models are showing a strong ridge developing in the western CONUS,
so dry and warmer conditions could be possible after the period.
Temperatures will be in the mid 80s to low 90s for the first half of
the period and then temperatures will drop into the 70s for the
second half due to the passage of the cold front.
&&
.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 530 AM MDT Sun Sep 4 2016
A few showers are within the vicinity of KMCK based on latest
radar, and trends should be to move east over the next few hours.
IFR CIGS have developed over KGLD, however this is very patchy
based on surrounding obs and satellite. Short range guidance
favors VFR within the next few hours, so I decided against
prevailing these conditions.
Scattered thunderstorms (some severe) are expected to redevelop
this afternoon and move northeast across the region through 06Z.
There is enough uncertainty regarding coverage that I was only
comfortable introducing vicinity groups. A strong low level jet
will develop late this evening, and should result in low level
wind shear at KMCK during the later part of the TAF period.
&&
.GLD Watches/Warnings/Advisories...
KS...Flash Flood Watch from 3 PM MDT /4 PM CDT/ this afternoon
through this evening for KSZ001>004-013>016-027>029.
CO...NONE.
NE...Flash Flood Watch from 3 PM MDT /4 PM CDT/ this afternoon
through this evening for NEZ079>081.
&&
$$
UPDATE...DR
SHORT TERM...DR
LONG TERM...CLT
AVIATION...DR
Area Forecast Discussion
National Weather Service Houston/Galveston TX
1011 AM CDT Sun Sep 4 2016
.DISCUSSION...
The 1200Z sounding at LCH showed a convective temperature of 88 degrees,
and at CRP 86 degrees. This temperature has already been reached
along the coast, resulting in a few showers that are moving
inland. 1200Z soundings support high temperatures between 90 and
92 degrees inland, and in the upper 80s on the coast.
Observational data is already indicating low-level directional and
speed convergence, hugging the coastline. Short term model
guidance from the HRRR and RAP suggests that this convergence zone
will stay anchored to the coast. However, some uncertainty with
regards to this solution as potential outflow boundaries may
result in a propagation of these showers and thunderstorm pushing
more inland into the early afternoon.
Sky grids have been adjusted to match current conditions, otherwise,
the forecast is on track. We will be monitoring trends, if short
term guidance is correct slightly higher POPs may be needed along
the coast for this afternoon.
8/43
&&
.PREV DISCUSSION... /ISSUED /
AVIATION...
showers are developing near the coast and along the coastal waters
- because of this, very nearly added a tempo for showers at GLS,
but the site seems to be in a relative lull in development, and
initiation appears to be taking place a little farther offshore
than in other spots. Because of this, will hold to VCSH at this
time. Went with shallow fog up north, as VSBY reductions have been
sporadic at most this morning. At SGR and LBX the reductions have
been more established, including MVFR visibilities at LBX, so I
was a bit more explicit there.
Later today, held VCSH from IAH to the south and west, to cover
for uncertainty in how much and where convection will fire today.
Precipitable water is around or below 2" in most of the guidance,
and so expect like yesterday that the best potential for showers
and storms will be southwest of the TAF cluster, but can`t
entirely rule out an isolated shower in the neighborhood today.
Luchs
PREV DISCUSSION... /ISSUED 430 AM CDT Sun Sep 4 2016/
DISCUSSION...
As expected somewhat drier air did filter into SE Texas yesterday
and remains in place this morning. Low temperatures should bottom
out in the low/mid 70s this morning but higher moisture just along
the coast will keep temperatures in the upper 70s. Radar shows
showers developing in the offshore waters of the Upper Texas Coast
and this activity should mark the leading edge of higher moisture
in the Gulf.
Upper air analysis shows a long wave trough over the west coast
with a ridge developing from the lower Mississippi River valley
through the Great Lakes. Troughing was located over the Mid-
Atlantic associated with post tropical cyclone Hermine. Hermine
should continue to meander off the Atlantic coast the next few
days before moving northeast Wednesday through Friday.
Blended precipitable water product does show more than 2 inches of
PW just off the coast and likely where current shower activity is
developing. Models show this moisture advecting into SE Texas
later today and decided to increase PoPs to 50 percent in the
afternoon with this surge in moisture. Precipitable water values
increase to around 2.2-2.3 inches on Monday and increase PoPs to
60 given model consistency for the last few days. Models still
show upper level ridging building over the lower Mississippi River
valley but the ridge may only restrict thunderstorm coverage from
wide spread to scattered. Even with scattered activity, most of SE
Texas should get meaningful rainfall. Most of the area can expect
0.25 to 0.5 inches of rain but some of these stronger storms could
still produce 1-2 inches of rain in an hour. Isolated 1-3 inch
amounts will be possible and could contribute to minor street
flooding or rapid rises on area bayous. Atmosphere will be more
than capable of high rain rates given CAPE around 2000-3000 J/kg
and the high moisture content.
After Monday the forecast remains on track with isolated to widely
scattered showers and thunderstorms each day. Precipitable water
values linger around 1.9 to 2 inches through the rest of the week
and should support at least a small chance of rain. The upper
level ridge does build Tuesday into Wednesday but then weakens
ever so slightly for the end of the week. Max temperatures should
top out in the low/mid 90s for the end of the week but will
largely depend on coverage of clouds/precip.
In the far extended the ECMWF does bring a cold front into the
area for Saturday while the GFS stalls this front north of the
area. Both models bring a stronger front into the area the
following Tuesday at 228hrs. Upper level pattern seems supportive
of a front with a trough pushing across the Great Lakes.
Overpeck
MARINE...
Light to moderate onshore winds are expected through the holiday
weekend, with the strongest winds emerging in the late afternoon
through the night both Sunday and Monday. As with this evening, the
winds will be near the threshold at which we normally urge small
craft to exercise caution. The pressure gradient should relax
slightly deeper into the new week, with winds coming down slightly.
Waves should continue in the 2 to 3 foot range for much of the week,
with 4 foot seas possible beyond 20 miles from shore. By late in the
week, a pattern change may disrupt the persistent light to moderate
onshore winds.
Luchs
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 92 75 90 76 93 / 30 10 60 20 30
Houston (IAH) 92 76 90 77 92 / 50 10 60 20 30
Galveston (GLS) 89 81 88 82 89 / 40 30 60 20 20
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
Discussion...43
Area Forecast Discussion
National Weather Service New Orleans LA
812 AM CDT SUN SEP 4 2016
...SOUNDING DISCUSSION...
Moisture is back up this morning and overall PW is above average
at 2.25 inches. Low levels are near saturated to 850 mb with
onshore flow from the southeast in that layer. This is bringing a
bit of wind convergence and a moisture boundary just inland from
the coast. Winds remain light and variable aloft. Plenty of
instability is in place with mixed layer CAPE at 2000 J/KG so some
storms will be heavy later. A lot of lightning was on the taller
storms yesterday.
Krautmann
&&
.PREV DISCUSSION... /issued 348 AM CDT SUN SEP 4 2016/
SHORT TERM...
A weak frontal boundary that had stalled across southern portions of
the forecast area has all but completely dispersed. This is
evident by surface observations that show lower to mid 70
dewpoints areawide with slightly higher numbers offshore. Surface
ridge centered well northeast of the area will build south and
west into the Gulf of Mexico and across Louisiana which will
cause southeast winds to develop and strengthen. The HRRR suggests
convection will initiate in the coastal warm sector this morning
and shift northward across the rest of the CWA late morning and
into the afternoon. Considering how the HRRR embarrassed medium
range models, especially the ECMWF, in terms its ability to
correctly forecast thunderstorm placement and timing yesterday,
the pop forecast today is heavily weighted on that model. The GFS
output for today is considered more of a supporting output, but
not much different than the HRRR. Model soundings once again show
an inverted-V with dry air aloft which would suggest the potential
for microbursts. A few storms could produce damaging winds in the
strong to maybe severe range. High temps are at or slightly above
guidance although areas south of Lake Pontchartrain may not get
higher than mid/upper 80s as T-Storm development could limit daily
warming.
Labor day will be much like today as a maritime upper level ridge
builds over the gulf south. This will continue to enhance moisture
return to the whole forecast area and subsequently higher chance for
rainfall. Expect a typical diurnal pattern with convection
initiating late morning and thunderstorms carrying over into the
afternoon and early evening hours. Overall pops should fall in the
50 to 60% range which is similar to the previous forecast.
LONG TERM...
The maritime ridge will begin to take on more continental
characteristics as it expands north and eastward midweek. This will
draw in drier air to the region from the northeast. That along
with increased subsidence will hinder daily thunderstorm
development for all but offshore locations with the caveat that
areas along the western fringe of the CWA could see isolated
storms. How long the ridge holds strong will determine how long of
generally dry period will remain in place.
MEFFER
AVIATION...
Most terminals should receive at least one ts today. TEMPO groups
should suffice for the most part while a few coastal locations may
even see prevailing for several hours. Should be able to show most
with prevailing VCTS by late morning. Obviously IFR conditions
within ts expected while outside of activity VFR expected.
Convective activity to dissipate overnight and back again Monday.
MARINE...
light winds and low seas are expected the next 5 days with only
concerns being near convection where gusts around 25 knots,
occasional lightning and isolated waterspouts will be the norm each
day. 24/RR
DECISION SUPPORT...
DSS code: Green.
Deployed: None.
Activation: None.
Activities: None.
Decision Support Services (DSS) Code Legend
Green = No weather impacts that require action.
Blue = Long-fused watch, warning, or advisory in effect or
high visibility event.
Yellow = Heightened impacts with short-fused watch, warning
or advisory issuances; radar support.
Orange = High Impacts; Slight to Moderate risk severe; nearby
tropical events; HazMat or other large episodes.
Red = Full engagement for Moderate risk of severe and/or
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 91 72 90 73 / 40 20 50 20
BTR 92 74 90 73 / 50 20 50 20
ASD 90 75 90 75 / 50 20 50 20
MSY 88 80 91 80 / 50 30 50 20
GPT 89 76 88 76 / 50 30 50 20
PQL 89 75 88 75 / 60 30 50 20
&&
.LIX Watches/Warnings/Advisories...
LA...None.
GM...None.
MS...None.
GM...None.
&&
$$
Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
1013 AM CDT SUN SEP 4 2016
.DISCUSSION...See updated information for land areas below.
&&
.UPDATE...Upper air analysis shows a trof of low pressure positioned
over the Virginias and Carolinas with a narrow mid level ridge
oriented from the Mid-South to across the FL Peninsula. Water vapor
satellite imagery is very similar to that observed on Saturday. A large
area of drier air aloft noted from the southeast US, westward to
across TX. South of the drier air, an east to west band of much
deeper moisture, pwats ranging from 2.0 to 2.3 inches, is aligned
from the northern FL Peninsula westward to across southeast MS. This
includes the southern half of the forecast area. When comparing the
availability of deep moisture with climatology, forecasters see that
pwat values are between 1 to 2 standard deviations above the mean for
early September. In the lower levels of the atmosphere and surface, a
weak pressure trof was analyzed to be draped across the I-10 corridor
to southern MS into southeast LA. This trof intersects the
anomalously high deep layer moisture along the coast. This feature
when combined with morning coastal instability (Mixed layer => ML
CAPE) values on the order of 1000 to 1500 J/KG, scattered to locally
numerous showers and storms persist per local radar returns.
The surface trof moves little thru the remainder of the day and when
combined with forecast of best ML CAPE confined to the southern zones
and presence of deep moisture, storms look to be more likely along
and south of a line from Andalusia AL to Wiggins MS. This is
shown in the latest gridded pop forecasts, which is also consistent
with the high resolution HRRR guidance and the 4KM-NAM. To a lesser
extent, the WRF-ARW. Over the central and northern zones, will
maintain scattered afternoon storm coverages. The stronger storms
will be efficient in producing locally heavy rains and potentially
localized to minor flooding over urban and other poorly drained
areas. Brief strong wind gusts in excess of 40 mph and frequent
lightning will also be likely in and near any of the stronger storms.
/10
&&
.PREV DISCUSSION... /issued 656 AM CDT SUN SEP 4 2016/
DISCUSSION...Updated for latest aviation discussion below.
AVIATION...
12Z issuance...VFR to MVFR cigs and visibilities through 05.18z.
Lower cigs and visibilities mostly in and around scattered to
numerous showers and thunderstorms beginning early this morning
continuing through early this evening...reforming again along the
immediate coast early mon morning. Some patchy fog with low stratus
will also be possible mainly around sunrise this morning and early
mon morning. Winds will be mostly southeast to south at 3 to 6 knots
early today increasing to 8 to 12 knots late this morning through
early this evening... becoming light and variable late this evening
through early mon morning...then becoming east to southeast at 5 to
10 knots by late mon morning. 32/ee
PREV DISCUSSION... /issued 443 AM CDT SUN SEP 4 2016/
NEAR TERM /Now Through Sunday night/...Upper trof mostly over the mid
Atlantic states stretching south along the eastern seaboard will
continue to lift east northeast through tonight followed by a sharp
ridge stretching from the Great Lakes region to the western and
north central gulf by 12z mon. At the sfc a weak quasi-stationary
frontal boundary/trof continues to linger near the nwfl/al and ms
coast this morning progged to drift southward and become diffuse
late today and tonight. Similar to yesterday this feature will
continue to be the main focus for better moisture convergence near
the surface as it waffles just north of the coast through this
afternoon resulting in another round of early morning showers and
thunderstorms along the immediate coast then gradually shifting
northward by late morning and afternoon as better heating inland
initiates a weak seabreeze circulation by mid to late afternoon.
Latest model soundings continue to show moderate instability across
the region today with mucapes starting out between 2500 to 3000 j/kg
just offshore and along the immediate coast shifting north over most
inland areas of the forecast area by early to mid afternoon. Lapse
rates continue to be marginal with a warm nose still showing around
6km suggesting better ridging moving in from the west. As a result we
will start out with likely pops along the immediate coast and just
offshore early today followed by likely to categorical pops
stretching across most of the lower half of the forecast area by
afternoon. The highest pops will be over the western Fl Panhandle
just inland from the coast stretching into eastern parts of Baldwin
county in Al. Similar to yesterday periods of very heavy rain with
rates up to 2 inches per hr or better possibly leading to some minor
or nuisance flooding locally... frequent cloud to ground lightning
and wind gusts possibly up to 40 mph will be the main threats through
early this evening.
Todays temps will be similar to yesterday due to more clouds than
sun along with good coverage of precip high temps will continue to
run slightly cooler than average ranging from the upper 80s to near
90 inland and the mid to upper 80s closer to the coast. Lows tonight
will fall to the lower 70s for most inland areas generally north of
the I-10 corridor and the middle 70s further south to the immediate
coast. 32/ee
SHORT TERM /Monday Through Tuesday night/...The weak surface
boundary currently extending east to west near the coast moves
southward over the Gulf by Labor Day. However...ample moisture and
daytime instability remain to fire off convection along a northward
moving late morning/afternoon seabreeze. Albeit expect areal storm
coverage to decrease Monday and even more so Tuesday as the airmass overlying
the North Central Gulf continues to gradually dry. PWATs Monday
remain elevated but decrease from above 2.0 inches and range from
around 1.8 to 2.0 inches. On Tuesday...PWATS plummet falling below
1.5 inches over most of our AL and FL zones as an upper level ridge
builds over the area. PWATs are expected to remain up over SE
Mississippi (1.8" to 1.9") so have continued chance wording for
thunderstorms there and slight chance elsewhere. Daytime highs should
generally climb into the low 90s Monday and low to mid 90s Tuesday.
Overnight lows are expected to trend cooler as drier air begins to
advect into the area...Monday night lows should fall into the low to
mid 70s closer to the coast and upper 60s to low 70s further inland.
Tuesday night will trend a little cooler upper 60s inland and
generally low 70s near the coast and mid 70s along it. /08
LONG TERM /Wednesday Through Saturday/...A strong upper level ridge
becomes established creating a period of dry weather over the area.
As a result...daytime high temperatures climb into the low to mid
90s. Efficient radiational cooling overnight should provide pleasant
early morning temperatures with lows expected to range from the low
to mid 70s near the coast and 60s inland. /08
MARINE...Main concern for today will be another round of
scattered to numerous showers and thunderstorms mostly in the
morning leading to periods of very heavy rain...frequent lightning
and gusty winds possibly up to 30 knots or slightly higher. Expect a
light southeast flow early today followed by a light to moderate
southerly flow by mid to late afternoon mostly from local seabreeze
circulations setting up later in the day due to afternoon heating
well inland. Long period swell and swell heights will continue to
decrease as high pressure builds west over the eastern and north
central gulf. 32/ee
&&
.MOB Watches/Warnings/Advisories...
AL...None.
FL...None.
MS...None.
GM...None.
&&
$$
This product is also available on the web at:
http://weather.gov/mob
Area Forecast Discussion
National Weather Service Marquette MI
752 AM EDT SUN SEP 4 2016
.SHORT TERM...(Today and tonight)
Issued at 503 AM EDT SUN SEP 4 2016
WV imagery and RAP analysis indicated sw mid/upper level flow from
the srn Rockies to the upper MS valley between a ridge over the
cntrl Great Lakes and a trough into the wrn CONUS. At the surface,
srly winds were also increasing through the upper MS valley between
high pres over the ern Great Lakes and a trough over the cntrl
Dakotas.
Today, with only a slow progression to the pattern srly winds will
continue to bring relatively dry air into Upper Michigan resulting
in mostly sunny skies. With 850 mb temps around 12C-13C, similar to
Saturday, expect max temps again in the upper 70s to around 80.
Tonight, the combination of a shrtwv trough moving from the Dakotas
to ne MN and strong theta-e advection with 40 knot sw 850 mb winds,
will support shra/tsra into wrn Lake Superior and possibly into wrn
Upper Michigan late tonight. since the pcpn will be moving into the
dry airmass over the region, the forecast maintains only chance
pops, mainly for the far west near Ironwood and Ontonagon.
Forecast MUCAPE values to around 500 J/Kg will limit TS strength.
Breezy south winds will keep temps from dropping off with min
readings in the upper 50s to the mid 60s, warmest where downslope
flow prevails near Lake Superior.
.LONG TERM...(Monday through Saturday)
Issued at 501 AM EDT SUN SEP 4 2016
A shortwave lifting ne through the Upper MS River Valley could bring
some showers/TS to western Upper Mi on Labor Day, but otherwise
broad sfc high pressure moving only slowly to the e combined with
mid level dry air under a high amplitude upper ridge will maintain
dry and warm weather across the forecast area thru Labor Day. As the
upper ridge flattens toward mid week and a slow moving cold front
crosses the area under a very moist airmass, shower/TS chances will
be on the increase later on Tue into Thu. Although the details are
still far fm certain, there could be some heavy rain during this
time over at least a portion of Upper MI. The period into Tue wl be
a warm one, but cooler wx should arrive for later in the week behind
the slow cold fropa.
Labor Day...Persistent higher heights/mid level dry air over Upr MI
should result in continued dry wx for at least the majority of the
cwa on Labor Day. Model guidance does show a shortwave lifting NE
thru MN. Accompanying dpva/weak deep layer q-vector convergence are
fcst to impact the western cwa and could bring some sct shra/tsra
into mainly the western portion of Upper MI. But given the fcst weak
height falls and fairly weak forcing fm the shortwave through a
relatively dry/stable mid level antecedent airmass, wl tend to favor
the drier end of the guidance. As a result, wl continue chc pops
western cwa for Labor Day with highest chc pops closer to Isle
Royale and closer to track of shortwave where deeper moisture and
better shortwave dynamics exist. Even if there are more clouds on
Labor Day especially over the W, h85 temps peaking at 17-18C wl
support max temps into the 80s away fm Lake Mi moderation. Pwats
rising to near 1.5 inches and dewpoints climbing into the lower to
mid 60s will also make for much more uncomfortably humid conditions.
Mon ngt/Tue night...Models indicate one shrtwv and assoc sfc wave
lifting NE thru the Dakotas/Mn Mon night into Tue morning with weak
dynamics fm shortwave again brushing the NW half of the cwa. A
similar absence of significant height falls associated with the
shortwave and continued persistent upper ridging wl tend to maintain
a more capped environment and may inhibit convection Mon night into
Tue morning even over the NW half where models show the slow-moving
cold front approaching fm the west. Models then indicate a second
shortwave riding over the frontal boundary as it moves into the
western half of Upper Mi Tue afternoon so for this reason wl
maintain going likely pops Tue afternoon across much of the forecast
area. If cap can be broken with shortwave, there is enough
instability as MUCAPEs rise to 1000-1500 j/kg and effective shear to
near 30 knots to maybe produce an isolated strong to marginally
severe storm Tue afternoon into Tue evening. Warm and humid
conditions wl prevail under deep SW flow that maintains higher pwats
in the 1.5-2.0 inch range. Expect min temps on Mon night to hold in
the 65-70F range under the tighter pres gradient/and mixing fm
stronger h925 SW winds up to near 35 kts per fcst soundings. High
temps on Tue should climb into the 80s, at least away fm Lake
Michigan moderation and the far W, where there wl likely be more
clouds associated with the weak cold fropa.
Wednesday through Sunday...Longer range models continue to show
gradual height falls over the Upper Lakes by mid week as the upper
ridge axis tends to flatten out and push east with the advance of
persistent upper troffing over western North America. Since the
passing sfc cold front wl be nearly parallel to the SW flow aloft,
models continue to show only slow progress with this frontal boundary
through the Upper Great Lakes region. There are still plenty of model
differences with the progress/placement of the front as well as on
the timing/track of a series of shortwaves and accompanying sfc low
pres waves fcst to move along the front. Nonetheless, this setup
along with fcst pwat up to 2 inches should bring the potential for
heavy rains to at least part of the cwa with model guidance
indicating Wed into Thu morning as best opportunity. This is also
consistent with the NCEP Day 3-7 Hazards Outlook which indicates
heavy rain potential for Wed into Thu. Most of the extended models
indicate a general break in the pcpn later Thu afternoon into Fri
with the hint of shortwave rdgg/mid lvl dry air and assoc sfc rdgg
into the area. At the same time, the persistent WSW flow aloft ahead
of mean troffing over the Rockies/Northern Plains could keep the
front close enough to allow upper disturbances to influence the area.
Models advertise the main mid-upper level trof moving in from the
Northern Plains Fri night and Sat along with a sfc trof/cold frontal
boundary and this will warrant higher chc pops for the Fri night into
Sat time frame. Although Tue night/Wed should still feature aoa
normal temps, cooler wx, especially daytime max temps, should
dominate toward the weekend as the mid-upper level trof moves in from
the Northern Plains and pulls in colder air behind the secondary cold
frontal passage.
&&
.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 751 AM EDT SUN SEP 4 2016
Expect VFR conditions at all 3 TAF sites this fcst period as the
incrsg S flow arnd hi pres moving toward New England continues to
tap dry air. With daytime heating/ mixing on Sun, included some
gusty S winds in the fcst for the more exposed IWD and SAW
locations. These gusty winds will dimininsh this evening with the
loss of mixing after sunset. Some llws may develop late tonight at,
mainly at IWD, as a low level jet increasing above the nocturnal
inversion. Showers and a few ts may approach IWD late tonight as a
disturbance and increasing moisture/instability approach the area.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 503 AM EDT SUN SEP 4 2016
Winds through the middle of next week are expected to remain at 20
kts or less. The only exception would be on Monday as south to
southwest winds may push above 20 kts in gusts over eastern Lake
Superior ahead of an approaching low pressure trough. Low pressure
crossing Lake Superior next weekend may result in westerly winds to
30kts across the Lake Superior depending on the exact track of the
low.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...Voss
AVIATION...JLB
MARINE...JLB
Area Forecast Discussion
National Weather Service Pueblo CO
423 AM MDT SUN SEP 4 2016
.SHORT TERM...(Today and tonight)
Issued at 423 AM MDT Sun Sep 4 2016
One shortwave is currently lifting out across northwest CO...kicking
off showers and thunderstorms along the contdvd at this early hour.
Next upper trof across southern NV will be lifting rapidly across
the forecast area during the afternoon. Drier air has worked in
over much of CO except for the far southeast plains where dew points
are still in the upper 50s/lower 60s as of 3 AM. Meanwhile...there
is still a pocket of moisture evident in WV loops across southwest
CO. As this latter shortwave trof approaches southwest CO this
morning...expect an early start to convective initiation along the
continental divide...with thunderstorms developing by late morning.
These will be spreading northeastward through the afternoon...though
with deep southwesterly downslope flow over the region...system will
have less moisture to work with as it cross the southeast mountains
into the I-25 corridor. By late afternoon...sfc trof axis will
likely lie along a line from Eads to Kim...and could see a few
thunderstorms develop along/east of this line during the late
afternoon/early evening. CAPE values rapidly increase towards the
KS border and position of the drier air along/west of the trof axis
will determine how much CAPE will be available in SE CO. NAM12
keeps values in the 500-1000 J/kg range...while GFS and hrrr look
drier with values generally under 500 J/kg. Deep layer shears will
be running around 40 kts...so if we can maintain enough low level
moisture/CAPE...then a strong to near severe storm or two will be
across the far southeast plains. However...threat appears greatest
to the east and northeast of the area. Gusty southwest winds will
spread over all of the area by this afternoon and this should help
warm temperatures to values similar to a couple degrees warmer than
yesterday. This will result in well above normal high temperatures
for this time of year...particularly for the southeast plains where
mid to upper 90s will be possible.
Tonight...thunderstorms will be done across the mountains by early
evening as drier air sweeps in behind the shortwave. Isolated
thunderstorms will be possible through the early evening hours
across the far southeast plains before activity shifts eastward and
out of the area. Lows tonight should stay on the mild side where
downslope winds continue into the lee trof overnight. Valley areas
in the mountains could be on the cool side given lower dew
points...clear skies and decoupling winds. -KT
.LONG TERM...(Monday through Saturday)
Issued at 423 AM MDT Sun Sep 4 2016
.Monday...First disturbance moves from the Great Basin into the
northern Rockies. A southwest to northeast surface trough develops
over the southeast plains of Colorado. Southerly surface flow
ahead of the trough will bring low level moisture northward. GFS
has over 1000 J/kg of CAPE along the trough while NAM is closer to
2000 J/kg. Bulk shears are around 30 to 40 knots. SPC has a
marginal risk extending into eastern Colorado, for locations near
the surface trough, stressing the potential for large hail and
damaging winds. Further west, some monsoon moisture will start
moving northward into Colorado, and it may reach the southern
portions of the mountains by Monday evening.
.Tuesday...Second disturbance moves northeast from the Great
Basin into the northern Rockies. Monsoon moisture will be more
abundant on Tuesday with increased chances for convection over the
mountains, and the greatest chances will be near the New Mexico
border. Further east, a southwest to northeast oriented surface
trough may extend across portions of the southeast plains of
Colorado. This trough could act as a focus for storm development,
and SPC has a marginal risk for portions of the southeast plains
of Colorado.
.Wedensday through Saturday...Flow aloft becomes westerly on
Wednesday bringing dry air aloft into the region with grids only
having silent PoPs. Airmass remains mild with temperatures at or
above seasonal normals. Flow becomes northwesterly later in the
weak with a possible cold frontal passage Friday or Saturday. The
colder air aloft stays to the north of the CWA, and frontal passage
should bring modest cooling to the plains and eastern mountains.
Airmass remains dry with only isolated convection over the
mountains by the end of the week. --PGW--
&&
.AVIATION...(For the 12Z TAFS through 12Z Monday morning)
Issued at 423 AM MDT Sun Sep 4 2016
VFR conditions expected at the TAF sites with southwest winds
increasing for most areas during the morning hours. TAF sites should
see winds increase between 16z and 18z...with gusts to around 30 kts
through the afternoon. Winds will gradually subside during the
evening hours. Isolated thunderstorms will be possible across the
mountains and far southeast plains this afternoon and evening...but
are expected to be too limited in coverage to pose much of a threat
for the TAF sites. Light diurnally driven winds are expected
overnight. -KT
&&
.PUB Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...KT
LONG TERM...PGW
AVIATION...KT
Area Forecast Discussion
National Weather Service Bismarck ND
501 PM CDT SUN SEP 4 2016
.UPDATE...
Issued at 500 PM CDT Sun Sep 4 2016
Quick update to issue a Severe Thunderstorm Watch for Logan,
LaMoure, McIntosh, Dickey Counties.
&&
.SHORT TERM...(This evening through Monday)
Issued at 246 PM CDT Sun Sep 4 2016
The main focus for the short term is potential severe thunderstorm
chances this afternoon and evening across the southern James
Valley.
A trough centered just east of Bismarck this afternoon will be the
focus for thunderstorm development. A slight clear patch in the
clouds across south central North Dakota has allowed temperatures
to climb into the 70s. The latest HRRR run indicates convective
initiation around 6 PM across far south central North Dakota. The
bulk of the instability should remain along and just south of the
ND/SD border. However, storm motion could bring stronger storms
across northern South Dakota into Emmons, McIntosh and Dickey
Counties later this evening. Plenty of moisture and shear will be
present along the front to sustain storms once they develop. The
main trough will exit the area tonight, with a slight break in
the shower/thunderstorm activity overnight before another wave
moves into western North Dakota Monday morning. Very high PWAT
values and training storms could create some hydro issues later
tonight with rainfall rates greater than an inch an hour.
Thankfully impacts should be short-lived as a break in the action
is expected overnight.
.LONG TERM...(Monday night through Sunday)
Issued at 246 PM CDT Sun Sep 4 2016
The rest of the week looks cooler and active as a broad cyclonic
flow will remain over the northern plains with several shortwaves
moving through. The most models highlight Wednesday for the best
chance for showers this coming week as a pronounced shortwave
moves through. There is a chance for showers and thunderstorms
through Saturday. Monday will be the coolest with upper 50s
northwest and 60s southeast. Then highs will be in the 60s to
lower 70s for the remainder of the week.
&&
.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1226 PM CDT Sun Sep 4 2016
Showers and thunderstorms will impact the area through the
day. The best chance for thunderstorms will be at KBIS, and KJMS
this afternoon. MVFR cigs with localized IFR cigs will develop
along with the potential for reduced visibilities in precipiation.
&&
.BIS Watches/Warnings/Advisories...
NONE.
&&
$$
UPDATE...AJ
SHORT TERM...AJ
LONG TERM...AJ
AVIATION...AJ
Area Forecast Discussion
National Weather Service Grand Forks ND
312 PM CDT SUN SEP 4 2016
.SHORT TERM...(This evening through Monday)
Issued at 305 PM CDT Sun Sep 4 2016
Forecast challenge in the short term will be T coverage/severe
potential. Earlier today high resolution models struggled with
current convection with RAP and HRRR doing the best of late. HRRR
has improved over the last several hours leading to somewhat
higher confidence on what will happen overnight.
Boundary from northern valley to near JMS and into central SD will
drift slowly east overnight. Clouds/rain have limited instability
especially across the northern 2/3rds of the forecast area.
Airmass becoming increasingly unstable from the far SW FA into SD.
This appears to be the favored location for convective initiation
later this afternoon or early evening. Convection will likely then
propagate NE along the boundary during the night so it may be
later before northern portions of the region from the valley west get
rain. Severe threat looks to be limited to the S-SW fa.
By morning boundary will be bisecting the FA from NE-SW.
Convection will probably be ongoing in the am most likely over the
ne fa. At prime heating front will be across the far se fa and
will have to monitor for severe potential there. Across the
remainder of the fa will maintain some chance pops but would not be
surprised if most areas stay dry. Column steadily cools during the
day with warmest readings over the far E-SE closer to the
boundary.
.LONG TERM...(Monday night through Sunday)
Issued at 305 PM CDT Sun Sep 4 2016
An upper level wave will be moving through the region on Monday
night. Models have surface low in eastern SD/SW MN Monday at 7 PM.
Most models have an inverted trough/cold front extending NE from the
low to the Arrowhead of MN...although the GFS is further west with
the front. There will likely be some elevated instability in the SE
forecast area, including the Fergus Falls and Wadena areas, Monday
evening. With effective shear of 40-50kts and MUCAPEs of 1500-3000
J/kg, a threat for severe storms will exist. A sharp theta-e
gradient will exist along the cold front...with a strengthening low
level jet by 10 PM. The front gets a nudge eastward later Monday
night as the upper wave passes to the north.
Tuesday looks generally dry with highs in the mid 60s north to mid
70s south and partly sunny skies. Another wave will bring a chance
for showers/thunderstorms on Wednesday/early Thursday. Yet another
wave will affect the area on Friday. All in all the pattern looks
active with highs generally in the mid 60s to mid 70s.
&&
.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1252 PM CDT Sun Sep 4 2016
Plenty of uncertainty on degree of tsra redevelopment later this
afternoon into the evening. For this any tempo groups limited to
the near term with vcts late afternoon into the evening. Will
follow guidance and keep with mvfr/ifr cigs later tonight as we
get on the cool side of inverted trough.
&&
.FGF Watches/Warnings/Advisories...
ND...None.
MN...None.
&&
$$
SHORT TERM...Voelker
LONG TERM...Knutsvig
AVIATION...Voelker
Area Forecast Discussion
National Weather Service GLASGOW MT
258 PM MDT SUN SEP 4 2016
.SHORT TERM...for northeast Montana...tonight through Tue...
A large trough of low pressure aloft is entrenched over the
northern Rockies region which places northeast Montana in a steady
moist SW flow aloft. Unfortunately, the precipitation models have
a difficult time pinning down the variable rain bands that result
from these dynamics. The HRRR and EC and the GEM seem to be the
more accurate models while the GFS and NAM are of next to no help
at all. Tried to blend the best consensus I could find for all
adjustments to the forecast. Because of the variable nature of
these rain showers, would not be surprised if some locations
accumulate over an inch of rain while others only receive a trace
of rain.
Tonight: The first wave of precipitation continues to do what it
has done for most of the day already - concentrate more over our
southern zones, making feeble attempts to extend northward toward
the international border only to peter out to just a trace.
Monday: The closed upper low center becomes an open wave and moves
directly over northeast Montana. The models improve just a bit
with consensus on the precip amount and placement. Best chances
for accumulating rain will be between Monday morning and Monday
afternoon and could easily be a bit more widespread than what we
experienced today.
Monday night the upper level wave weakens and lifts northeastward
over Saskatchewan and ends the rain from SW to NE across many
locations by the overnight hours.
Tuesday as the flow becomes more zonal, only lingering chances for
trace to minimal amounts of rain can be expected over our NE
zones.
Expect temperatures around 20 degree below averages for this time
of year through Tuesday morning as the cold continental air mass
from Canada continues to hold sway. BMickelson
.LONG TERM...Tue night through Sun...
Going forecast has a good handle and 12z models didn`t provide
much need for change. At the end of the period, a disturbance
brushes the area from the north and could knock temps down along
with bringing the chance of showers. TFJ
Previous Discussion...
Cool conditions expected from midweek through next weekend with
longwave upper trof over North America. Lowered heights and the
southward shift of the jet will keep temperatures below normal for
the period.
Main chance for rain will be with a shortwave trof pushing
through the northern Rockies midweek. System tracks along the
Canadian border with thunderstorms possible ahead of the low
Tuesday night into Wednesday. A second wave follows on Thursday
but models differ on how far south it dips so uncertainty is
increased regarding rain chances. Ebert
&&
.AVIATION...
Scattered rainshowers are expected to diminish a bit tonight with
another surge moving Labor Day.
VFR conditions will be knocked down by heavier showers for the
remainder of today, especially at KGDV, but more widespread MVFR
conditions are expected Labor Day with the next surge of rain.
Winds should remain steady from the E or NE but speeds should
remain less than 15 kts. TFJ
&&
.GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
weather.gov/glasgow
Area Forecast Discussion
National Weather Service Hastings NE
311 PM CDT SUN SEP 4 2016
.SHORT TERM...(This evening through Monday)
Issued at 227 PM CDT Sun Sep 4 2016
We have a chance for thunderstorms this evening. There will be a
couple thousand J/kg of most unstable CAPE (upwards to near 4,000
per the NAM) with decent bulk (0-6km) shear around 45 knots to
support updrafts capable of large hail around half dollar size (or
larger) and thunderstorm wind gusts around 60 mph. Initially,
there is a chance for some of the early thunderstorms to develop
into supercells and there will be a small threat for tornadoes
before storm mode goes more into a cluster of storms. The higher
instability is across western portions of the county warning
area...and I believe thunderstorms will impact our area here
initially. A surface trough is currently in place across western
parts of the Central Plains. Thunderstorms are already developing
across eastern Colorado. The HRRR is initializing well and
capturing this in the 19Z run. The HRRR brings these storms into
western parts of our area as early as 6pm.
A flood warning is in effect for portions of north central Kansas
until 730 pm tonight. Please see the latest Flood Warning product
for more information. Chances for additional rainfall look more
favorable for areas north of the flooded area.
.LONG TERM...(Monday night through Sunday)
Issued at 227 PM CDT Sun Sep 4 2016
Throughout the extended there are multiple chances for
thunderstorms. Some of these chances could produce storms capable
of strong to severe weather. The Storm Prediction Center has us
outlooked the next several days in a row. Monday is really the
only day that doesn`t look as favorable for thunderstorms...and
really the only dry period in the forecast until next weekend.
Any additional rainfall in those areas that have already received
a lot of rainfall could potentially be prone to more flooding.
This will need paying attention to over the course of next week,
in particular north central Kansas, which doesn`t need
anymore rainfall.
&&
.AVIATION...(For the 18Z KGRI/KEAR TAFS through 18Z Monday afternoon)
Issued at 1246 PM CDT Sun Sep 4 2016
The TAF sites will be under MVFR conditions through the beginning
of the TAF period before ceiling become more in the 5K foot range.
There will be a chance for thunderstorms later this evening that
could impact the terminals, during which time the conditions may
go to MVFR or even IFR. The timing is a little uncertain at this
time but it should be around 00 for KEAR and perhaps closer to 02Z
for KGRI. The other concern is the low level wind shear later this
evening as the low level jet kicks in. Around 1500 feet there will
likely be a 50 knot jet with surface winds around 15 knots.
&&
.GID Watches/Warnings/Advisories...
NE...None.
KS...None.
&&
$$
SHORT TERM...Guerrero
LONG TERM...Guerrero
AVIATION...Guerrero
Area Forecast Discussion
National Weather Service Goodland KS
203 PM MDT SUN SEP 4 2016
.SHORT TERM...(This evening through Monday)
Issued at 152 PM MDT Sun Sep 4 2016
Main concerns once again are thunderstorm coverage and heavy
rainfall/flash flooding/flooding concerns. Confidence is lowered
due to poor performance of models with yesterdays event, and some
model disagreement on how the evolution of tonight will pan out.
Air mass remains very moist and unstable. Area soundings this
morning showed precipitable water values near 1.5 inches.
A persistent instability/theta-e axis remains draped across the
center of the area from southwest to northeast. There one surface
boundary near the western end of the area and another draped over
the eastern end. PV/Satellite analysis show a decent shortwave
moving in from the southwest. At the same time all the models show
a right rear quadrant of the upper draped across the area. The
shortwave and jet lift move across the area from west/southwest to
the east through the evening.
Where the models are having trouble is where to put the
development. Some have it in the west and others in the east.
Considering that currently thunderstorms have developed and are
now moving into the western portion of the area, that looks to be
the way to go. Current trends favor the Rap and Hrrr.
So expect scattered thunderstorms producing heavy rainfall to move
across the area once again. Due to instability and shear in place,
severe looks likely as well. All in all a similar setup to the
last few days. So will keep the flash flood watch going with the
northeast portion of the area extremely susceptible to more
rainfall and flooding.
For Monday...with exception of jet lift, setup looks similar
tomorrow. Instability/moisture axis remains in the same place. So
more thunderstorms will be expected along with locally heavy
rainfall and possible severe.
.LONG TERM...(Monday night through Sunday)
Issued at 145 PM MDT Sun Sep 4 2016
Trough extends down out of western Canada all the say into the
southern portions of California Monday night into Tuesday morning
with high pressure over the southern Mississippi Valley. The surface
boundary draped from southwest to northeast across the CWA continues
to remain nearly stationary as we head through the day on Tuesday.
This will provide a focus for scattered thunderstorm activity
through the afternoon and into the evening once more with only
moderate instability and relatively weak upper level support
provided by passing shortwaves. A cold front will push through the
region later on Tuesday with slightly drier air behind it that will
linger into the middle to end of the week. Dry weather prevails
through Saturday with another, stronger cold front traversing the
region on Friday. Due to dry air in place preceding the front, PoPs
will be low across the CWA and should remain east of the region.
Afternoon high temperatures will be in the middle to upper 80s
Tuesday with a few 90 degree locations in the eastern portions of
the CWA. Slightly cooler highs prevail for Wednesday and Thursday
with highs in the middle 80s. Cold frontal passage will cool things
off a bit heading into Friday and Saturday with afternoon high
temperatures reaching the upper 70s to lower 80s.
&&
.AVIATION...(For the 18Z TAFS through 18Z Monday afternoon)
Issued at 1136 AM MDT Sun Sep 4 2016
Generally clearing skies are being observed at both TAF sites with
VFR conditions at kgld and becoming VFR at KMCK. We will see
another chance of thunderstorms this afternoon at both locations
with a better chance at KMCK. Stayed with VCTS at KGLD due to
uncertainty with regards to the location of the TS initiation. A
relatively strong low level jet will form and bring LLWS to KMCK
beginning later this afternoon.
&&
.GLD Watches/Warnings/Advisories...
KS...Flash Flood Watch until midnight MDT /1 AM CDT/ tonight for
KSZ001>004-013>016-027>029.
CO...NONE.
NE...Flash Flood Watch until midnight MDT /1 AM CDT/ tonight for
NEZ079>081.
&&
$$
SHORT TERM...BULLER
LONG TERM...TL
AVIATION...TL
Area Forecast Discussion
National Weather Service Miami FL
441 PM EDT SUN SEP 4 2016
.SYNOPSIS...
Showers and thunderstorms will continue across the northern
interior and the Gulf coast regions this evening. Otherwise, dry
conditions should prevail for the east coast metro. Tomorrow, an
increase in moisture will ramp up shower and storm activity
area wide. As high pressure builds over the Atlantic by mid week,
a typical summer weather pattern should return to South Florida.
With a return to east to southeast flow, scattered
afternoon/evening convection will mainly affect the interior and
Gulf Coast.
&&
.DISCUSSION...
Water vapor imagery continues to show a band of elevated mid and
upper level moisture stretching to the south and southwest from
post Tropical Storm Hermine down toward the Gulf of Mexico.
However, over South Florida, dry/sinking air was observed. This
subsidence has acted to keep convection at bay this afternoon.
The 12Z KMFL sounding indicated a distinct dry layer around 700 mb
with a capping temperature inversion. By late afternoon, light
east winds in the lower levels will allow for a sea breeze
convergence over the western interior. Both the HRRR and HiRes WRF
generate storm activity over a general area stretching from
Naples to Lake Okeechobee into the evening. This has been
reflected well in the grids. By late tonight, the 12Z GFS
indicates a moisture surge pushing across the Atlantic waters and
towards the East Coast metro. Thus, pops will increase tonight
into tomorrow morning along the Atlantic coast. By Monday, deeper
moisture will advect into the region from both the north and east,
creating the potential for an active day of showers/storms area
wide. With the swath of moisture lingering over South Florida
through late Monday, the chance of showers and storms will
continue into the night. The main threats from the strongest
storms will be brief heavy rain, gusty winds, and frequent cloud
to ground lightning. Heat index on Monday will be peaking between
100-104 degrees, with highest values over southern Collier County.
Tuesday through the weekend, high pressure building over the
Atlantic will bring a return to the more typical summerlike pattern
to South Florida. Highest chances of afternoon storms will be
over the interior and Gulf Coast. During the nights, activity may
shift back towards the Atlantic coast.
Beaches: From Monday afternoon through Wednesday, models project a 3-
4 foot 11-12 second swell, generated by Hermine, to drop southward
down our Atlantic coastal waters. This scenario would create
elevated surf along the Atlantic beaches and an enhanced rip current
risk. Will continue to monitor NWPS output as the swell approaches.
&&
.AVIATION...
The winds will remain from the east around 10 knots over the east
coast taf sites this afternoon before decreasing to 5 knots or
less for tonight. The winds at KAPF taf site will continue to be
westerly this afternoon at 5 to 10 knots before going light and
variable. The weather will remain dry through this evening at most
of the taf sites, before some showers could affect the east coast
taf sites for late tonight. Therefore, VCSH will be added after
06Z for the east coast taf sites and VCSH for KAPF taf site
through 00Z this evening. The skies and ceilings should remain in
the VRF conditions this afternoon into tonight at all of the taf
sites.
&&
.MARINE...
As a high pressure ridge continues to build across the Atlantic
through late week, winds will turn light and easterly. There will
be a chance of showers and thunderstorms throughout the period. A
11-12 second swell, generated, by Hermine, will push south through
the Atlantic coastal waters Monday afternoon through early
Wednesday. Seas could peak around 3-5 feet east of Miami-
Dade/Collier counties and 5-7 feet in the coastal waters east of
Palm County. Conditions will begin to improve by late Wednesday.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 79 90 77 87 / 20 60 40 50
Fort Lauderdale 80 89 78 88 / 30 60 40 50
Miami 80 90 78 89 / 30 60 40 50
Naples 77 91 75 89 / 40 60 30 60
&&
.MFL Watches/Warnings/Advisories...
FL...None.
AM...None.
GM...None.
&&
$$
SHORT TERM...27/JT
LONG TERM....27/JT
AVIATION...54/BNB
Almost did a copy and paste of the previous forecast discussion
here...as very quiet weather with few forecast changes needed
with the afternoon package. Large upper ridge becomes entrenched
over most of the Eastern U.S. by Tuesday...with the exception of
New England...where Hermine will remain just to the South before
exiting on Wednesday. As the ridge builds...dewpoints and
temperatures will rise with the heat index climbing into the mid
to upper 90s by Wednesday. So sticky and uncomfortable weather
with the ridge overhead and very little chance for any rain.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 145 PM Sunday...
By Thursday...differences in model progression of an approaching front
become apparent...and thus forecast confidence decreases. The 0z
ECMWF depicts a largely moisture-starved boundary approaching the
forecast area by 0z Friday with the latest 12z GFS a few hours
faster and notably more wet. The latter reflects more recent
trends in the forecast and therefore introduced slightly higher
PoPs as a result.
Beyond this system...the forecast becomes significantly more
muddled as the front early Friday morning never quite appears to
make it through the Ohio Valley. PoPs and temps on Friday were
adjusted slightly to reflect shower potential along this
boundary. On Saturday...the lingering boundary retreats northward
as southwest flow pushes in over the area. By 0z Sunday...the
ECMWF depicts a cold front along the Ohio River pushing
southeast...while the GFS is slightly slower with this boundary
stretching from central Ohio into Indiana. Chance PoPs were adjusted
slightly in the grids to reflect these model differences at this
time. Beyond this front...drier weather appears to settle into the
region for Monday...however confidence at that range is low at
this time.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
00Z MONDAY TO 00Z TUESDAY...
VFR conditions this evening will give way to some patchy dense
river valley fog late...resulting in areas of IFR or worse fog.
Given the lack of fog last night and little change in
setup...stuck close to a persistence forecast with some MVFR at
KCRW/KHTS/KPKB late. Greatest confidence in KEKN experiencing
dense fog with VLIFR coded up by 06Z.
VFR conditions return areawide Monday with just a few flat cu
around amid a light NW wind.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z TUESDAY...
FORECAST CONFIDENCE: High through midnight then medium through
daybreak and High again tomorrow.
ALTERNATE SCENARIOS: Timing and coverage/intensity of fog could
vary overnight into the morning hours. KCRW may experience IFR or
worse fog late tonight.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
UTC 1HRLY 22 23 00 01 02 03 04 05 06 07 08 09
EDT 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05
CRW CONSISTENCY H H H H H H H M M M L L
HTS CONSISTENCY H H H H H H H H H H H L
BKW CONSISTENCY H H H H H H H H H H H L
EKN CONSISTENCY H H H H H H H M M M L L
PKB CONSISTENCY H H H H H H H H H H M L
CKB CONSISTENCY H H H H H H H H H H H L
AFTER 00Z TUESDAY...
No widespread IFR expected...but valley fog could bring IFR
conditions during the early morning hours each day as ridge of
high pressure remains overhead.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...None.
OH...None.
KY...None.
VA...None.
&&
$$
SYNOPSIS...MPK/MAC
NEAR TERM...MPK/30
SHORT TERM...MPK
LONG TERM...MAC
AVIATION...30
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
314 PM CDT SUN SEP 4 2016
.SHORT TERM...(This Evening through Monday)
Issued at 314 PM CDT SUN SEP 4 2016
Overnight/early day convection has diminished with some lower
cloud building in as low level moisture increases. Water vapor
showing fast southwest flow over the Central Rockies and Northern
Plains with shortwave making quick progress into western Colorado
early this afternoon and scattered convection has developed ahead
of it. Breezy southerly winds helping push temps tin the lower and
middle 80s with dewpoints near 70.
Will likely see at least isolated activity persist in western
portions of the state through the afternoon. HRRR has been consistent
in more of a broken line of storms forming, but even it struggles to
maintain this activity into the CWA. Hard to completely rule out a
stray storm making it this far east but will keep a mention out.
Modest isentropic upglide resumes tonight over a 50kt south-
southwest low level jet with moisture in the low-mid levels not very
near saturation at any particular level. Again could see something
isolated develop mainly after midnight to just after sunrise but
don`t believe a mention is in order. The low level jet and high
dewpoints should keep lows in the lower 70s for the most part.
Stronger southerly winds, modest warm air advection from the
overnight, and less cloud should allow for Labor Day highs around
90.
.LONG TERM...(Monday Night through Sunday)
Issued at 314 PM CDT SUN SEP 4 2016
For the extended period, the general idea from the models is for
southwest flow aloft to transition to more of a of a progressive
pattern with shortwave troughs periodically moving through the
northern and central plains by the end of the work week and the
weekend. But before the transition, increasing moisture is progged
to occur along a surface trough/frontal boundary that sets up
just to the west and north of the forecast area through the middle
of the week. Models suggest that by Wednesday, a subtropical
fetch of moisture will get pulled into the area with PWs
approaching 2 inches. So the period from Wednesday through Friday
looks to be unsettled with some instability and reasonable flow
for storm organization.
For Monday night and Tuesday, the model consensus is for the
surface trough/front to remain to the northwest of the forecast
area with not much in the way of synoptic scale forcing
anticipated. With this in mind have kept a dry forecast until
Tuesday night when the forecast shows some small POPs across far
northern KS as the boundary gets a little closer. Temps are
forecast to be above normal. Persistent southerly flow and
increasing low level moisture should keep lows in the lower and
middle 70s. Highs Tuesday are expected to be around 90.
For Wednesday through Friday night, the forecast has a chance POP
for the reasons mentioned above. Models show an upper level trough
passing to the north of the forecast area Wednesday which doesn`t
really give much of a push to the surface boundary and allows it
to kind of stall out across northern KS and southern NEB. Large
scale forcing appears to remain subtle but there are signs for a
vort max to lift across the area Wednesday and Wednesday evening.
The stronger flow is expected to remain just north of the area so
odds for severe weather appear to be greater over northern KS
Wednesday where models increase deep layer shear. By Thursday the
boundary becomes less defined so a lack of focus for convective
development makes forecasting mesoscale details with confidence a
little tricky. Nevertheless the expected instability could lead
to scattered strong storms. By Friday, Models bring another upper
trough through the plains and a better push to the frontal
boundary. The addition of lift from the cold front with the
anticipated instability may provide the best opportunity for
precip.
The main uncertainty in the forecast is how strong the push to the
front on Friday will be. The ECMWF is quite a bit stronger with
the surface high behind the front and as a result is quicker to
move the boundary through the area and slower to develop return
flow on the back side of the surface ridge. The Canadian seems to
be in the GFS camp in terms of the magnitude of the surface ridge
behind the front. So the forecast is a compromise of the
solutions. Have a dry forecast for Saturday and Saturday night
with all guidance showing the boundary at least through the
forecast area by 12Z. Additionally have kept a slight chance POP
for Sunday from the model consensus thinking the ECMWF may be to
strong with the high pressure and there could be some warm air
advection back into the forecast area. Temps trend cooler for
Saturday and Sunday, but not nearly as cool as the ECMWF would
suggest.
&&
.AVIATION...(For the 18Z TAFS through 18Z Monday Afternoon)
Issued at 1219 PM CDT SUN SEP 4 2016
VFR conditions anticipated. Main challenges are surface winds and
wind shear onset/speed/heights but only minor changes made.
&&
.TOP Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...65
LONG TERM...Wolters
AVIATION...65