Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/13/17
Area Forecast Discussion
National Weather Service Wakefield VA
936 PM EDT Sat Aug 12 2017
.SYNOPSIS...
A cold front will slowly sag south through the local area this
evening into early Sunday morning. The front will stall across
North Carolina on Sunday, and will push back north Sunday night
into Monday as a wave of low pressure moves along the boundary.
Additional areas of low pressure will move along the front into
Tuesday, with high pressure finally building north of the region
by Wednesday.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Latest analysis indicating a sfc cold front from ern PA SW to
the central/southern Appalachians. A prefrontal sfc trough
remains in vicinity of the Chesapeake Bay. Currently, much of
the convection is ahead of the cold front and pushing toward the
Lower MD Ern Shore as of 930 pm. The earlier convection has
dissipated, and hence the Flash Flood Watch for NE NC/SE VA has
been cancelled. The highest PoPs (~60%) late this evening will
be for the MD Ern Shore (which could exacerbate flooding in and
around Salisbury), with the last several runs of the HRRR
suggesting some of the pre- frontal convection propagating into
central VA through 06z (30-40% PoPs), with some re- development
possible (~30%) near the VA/NC border toward sunrise. Otherwise,
PoPs will be aob 20% overnight. Warm and humid with lows
ranging from the u60s NW to the m70s SE VA- NE NC.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
The frontal boundary will linger just S of the local area or
near the SE VA/NE NC border Sun afternoon thru Mon...maintaining
chc to likely PoPs across srn VA-NE NC into Sun night w/ PoPs
aob 15% central/N. Flow aloft turns back a bit to the SW later
Sun night/mon, lifting the boundary back N. PoPs increase back
to 40-60% for much of the CWA (still highest S) Mon into Mon
evening as the boundary is pushed back N. Highs Sun and Mon
80-85F. Lows Sun night in the m-u60s N to 70-75F S. The front
lingers over the S Tue, as tropical low pressure remains well
offshore. PoPs Tue drop off across the N, but remain in the high
chance range over the S/SE. Highs tue again mainly 80 to 85 F.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Frontal boundary will be laying acrs NC and off the coast for
Tue night thru Wed, then gets pushed well S of the area for Wed
night thru Thu, as sfc high pressure builds into the region then
off the coast. Will have slgt to chc Pops over srn half of the
area Tue night and Wed, then mainly dry conditions (10-14% Pops)
for Wed night and Thu. At least slgt chc to chc Pops return for
Thu night thru Sat, as a trough of low pressure and a cold front
affect the region. Highs will range fm the mid 80s to near 90
thru the period, with lows ranging fm the mid 60s to lower 70s.
&&
.AVIATION /02Z SUNDAY THROUGH THURSDAY/...
Current radar analysis shows widely scattered showers/thunderstorms
across portions of the region, but the majority of the activity
from earlier has dissipated. A cold front crosses the region
late tonight through early Sunday morning bringing another
chance of showers and thunderstorms. SBY will have the best
chance of seeing rain/storms overnight with lower confidence at
other sites. MVFR ceilings will linger across much of the region
through early Sunday morning with the potential for IFR
ceilings across southeastern portions of the area. Conditions
improve from north to south across the region on Sunday with
potentially sub-VFR conditions lingering across far southern
portions of the region.
Outlook: Unsettled conditions with periodic convection continues
through Tuesday as a boundary stalls across the region, allowing
for a series of disturbances to cross the area. &&
.MARINE...
No headlines in the short term tonight thru Mon. A cold front
will drop acrs the waters late tonight into Sun morning. Expect
SSW winds 5-15 kt this evening/early tonight, will shift to the
NW or N very late tonight into Sun morning behind the frontal
boundary. That boundary will then remain just S of the area or
near the SE VA/NE NC border fm later Sun thru at least Tue. Sfc
high pressure will then push that boundary well to the S Wed
into Thu. N winds 5 to 10 kt will become NE during Sun, then
expect NE thru SE winds 5 to 10 kt Sun night thru Wed.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...None.
&&
$$
SYNOPSIS...LKB
NEAR TERM...AJZ/LKB
SHORT TERM...ALB/LKB
LONG TERM...TMG
AVIATION...AJB/MPR
MARINE...TMG
Area Forecast Discussion
National Weather Service Albany NY
845 PM EDT Sat Aug 12 2017
.SYNOPSIS...
A cold front will sweep through the region tonight. A cooler
and less humid air mass will return to the region tomorrow. The
fair and dry weather will continue on Monday as high pressure
builds in with seasonable temperatures.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
SEVERE THUNDERSTORM WATCH 447 IS CANCELLED AS OF 8PM.
The severe thunderstorm watch has been cancelled. The near-
severe line of thunderstorms stretches from southern Vermont
back into Columbia County, NY. This line has not produced any
severe weather in some time. It is not out of the question that
a rogue severe report could still be possible. But in general,
the threat for widespread severe has ended.
HRRR suggests areas to west of ongoing convection have seen the
last of precip for the night. SPC meso analysis still shows
MUCAPE running around 500 j/kg. (ALY sounding was delayed due to
thunderstorms in the area.). Will use the HRRR and current
radar to time the convective line out of the CWA. Then maintain
slight chance for TSRA/SHRA into the overnight hours. Some
patchy fog is likely as well.
The main front is located near Penn Yan NY. The front will clear
the CWA overnight. Low-level cold advection occurs in the wake
of the cold front with low temps in the mid 50s to lower 60s.
The winds will increase out the west/northwest at 10 to 15 mph
towards daybreak. It will feel less humid on Sunday.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
The period will be dominated by high pressure.
First, an upper level trough will clear the region Sunday
morning. There is a slight chance of showers through the
morning. By afternoon, high pressure builds in and remains in
control through Monday night. Another trough will approach the
area on Monday night.
With high pressure in place, skies should be mostly clear
through the period.
Temperatures will average near normal, with dew points below
normal.
&&
.LONG TERM /TUESDAY THROUGH SATURDAY/...
The extended opens with a weak short-wave trough moving across the
forecast area. This short-wave is associated with a broad upper
level trough over southeastern Canada extending southeast into the
Northeast. This feature should move through quickly with limited low-
level moisture and instability to work with, so only a slight to low
chance of showers was kept in the forecast. Temps look seasonable in
the upper 70s to lower 80s in the valleys, and upper 60s to mid 70s
over the higher terrain.
Tuesday night through Wednesday night...the short-wave quickly moves
east with the upper level trough sliding downstream with high
pressure building in from the Great Lakes Region and east/southeast
Ontario. Mid and upper level heights rise upstream for this period
of dry weather, but another low pressure system will be moving into
the upper Midwest/western Great Lakes Region by Wed. Overall, fair
and dry weather is expected for the mid-week with lows in the 50s to
lower 60s, and highs in the 70s to lower 80s with a few upper 60s
over the high peaks of the southern Adirondacks, southern
Greens, and eastern Catskills with comfortable humidity levels.
Thursday...Clouds increase Thu ahead of a warm front to the low
pressure system moving into the Great Lakes Region. There continues
to be some timing issues with the medium range guidance and we went
with a slight to low chance of showers and isolated thunderstorms
especially Thu pm.
Thu night into Saturday...The chances for showers and thunderstorms
increase THU night into FRI with the warm front lifting north across
portions of the region. A series of weak low pressure systems may
move along the boundary with the zonal flow aloft. POPS were raised
into the high chance category during the THU night to FRI time
frame. The frontal boundary may still be near the region heading
into the weekend with still a chance for showers and isolated
thunderstorms. Temps look seasonable near this time frame.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
Still experiencing transmission difficulty with the KGFL
observation. Thus AMD NOT SKED is added to the TAF.
The only terminal with issues over the next hour or so is KPSF.
Here a line of convection is just about on top of the airport.
So, have included prevailing TSRA there. Elsewhere, the threat
of thunder has ended at KALB and KGFL. For KPOU, high resolution
models suggest the convective line will weaken before reaching
the terminal. So have only included VCSH at KPOU. Looking for
all terminals to drop to IFR in CIGS and VSBY overnight in BR.
Once BR clears Sunday morning, VFR conditions will take hold for
the remainder of the day.
Outlook...
Sunday Night: No Operational Impact. NO SIG WX.
Monday: No Operational Impact. NO SIG WX.
Monday Night: No Operational Impact. Slight Chance of SHRA.
Tuesday: Low Operational Impact. Slight Chance of SHRA.
Tuesday Night: No Operational Impact. NO SIG WX.
Wednesday: No Operational Impact. NO SIG WX.
Wednesday Night: No Operational Impact. NO SIG WX.
Thursday: Moderate Operational Impact. Chance of SHRA...TSRA.
&&
.FIRE WEATHER...
Showers and thunderstorms this afternoon and evening. Best
coverage will be along and north of I-90.
Drier weather works in for Sunday and Sunday night.
Humidity levels will be at or above 90 percent tonight and
Sunday night. Humidity on levels on Sunday will be as low as 50
percent.
South winds tonight will yield to northwest winds on Sunday.
Winds on Sunday will be northwest at 10 to 15 mph.
&&
.HYDROLOGY...
Showers and thunderstorms will bring rainfall to much of the HSA
this afternoon and evening. Basin average rainfall will range
from 0.25-0.50 inch across the northern third of the HSA to
around 0.1 inch to the south. Any one thunderstorm is capable of
producing 1-2 inches of rain. This could lead to some poor
drainage flooding of low lying areas. . No river flooding is
expected.
High pressure builds in for much of the upcoming week bringing
dry conditions.
For details on specific area rivers and lakes, including
observed and forecast river stages and lake elevations, please
visit the Advanced Hydrologic Prediction Service /AHPS/ graphs
on our website.
&&
.EQUIPMENT...
The KENX radar will be down through early next week due to
azimuthal motor and gearbox problems. Technicians will need to
be brought in from the Radar Operations Center.
In addition, KGFL ASOS continues to experience intermittent
outages.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Wasula
NEAR TERM...OKeefe/Wasula
SHORT TERM...OKeefe
LONG TERM...Wasula
AVIATION...OKeefe
FIRE WEATHER...BGM/OKeefe
HYDROLOGY...BGM/OKeefe
EQUIPMENT...Staff
Area Forecast Discussion
National Weather Service Bismarck ND
909 PM CDT Sat Aug 12 2017
.UPDATE...
Issued at 858 PM CDT Sat Aug 12 2017
Now seeing the short wave circulation in the radar reflectivity
and this should track southeast with time tonight. Updated the
POPs and QPF with the latest HRRR model run and also averaged the
QPF with the HRRR. Will see more rain across south central North
Dakota tonight. The latest CAM models, especially the RAP, bring
in fog over more of the south central. With the recent rains
extended the areas of tonight further east, but did not go to the
James river valley.
UPDATE Issued at 710 PM CDT Sat Aug 12 2017
Focused on the south central for heavy rain with the
thunderstorms this evening. generally increased POPs to likely
across this area.
UPDATE Issued at 446 PM CDT Sat Aug 12 2017
Quick update for the band of thunderstorms from Beach to Hazen
to south of minot. This area of thunderstorms has been producing
heavy rain. Do not expect flash flooding but getting some reports
of standing water on roads, along I-94 near Medora for example.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 248 PM CDT Sat Aug 12 2017
Latest GOES16 water vapor imagery loop shows a mid level upper
low circulating over northwestern ND, soon to transition south as
a stronger shortwave rotates and into southwest/south central ND
this evening. The mid/upper low slowly meanders into the southern
James River Valley after midnight. Areas of fog 05z-15z Sunday for
southwest and south central ND has been added to the gridded
forecast per HRRR/RAP13 Surface Visibility Forecast.
For this afternoon and evening, per water vapor imagery, our
attention is directed toward a pair of 700mb-500mb shortwaves
noted over Dawson and Custer Counties in eastern Montana. The
GFS/RAP13 have both initialized this very well with the current
location, and begins pushing these shortwaves into southwestern
ND 21z-00z, then into far south central 03z-06z, and exiting the
southern James River Valley 12z-15z Sunday. Large scale ascent
increases this afternoon southwest and far south central in
response to the shortwave aloft and the left exit region of a 60kt
300mb jet streak scooting through southeastern MT/southwestern
ND. A cold pocket of -16C also aiding in destabilization. Air
parcels will encounter moderate instability with mixed layer CAPE
between 1000-2000 J/kg, Effective Bulk Shear values of 40kt, and
mid level lapse rates around 7.5C/km. With that said, will
continue with previous forecasts and maintain a mention of severe
thunderstorms in far southwest and into far south central ND
through early this evening. This is also in line with the Marginal
Severe Thunderstorm Risk per SPC. Main threats of large hail and
damaging winds continue. Localized heavy rainfall (1 to 2 inches)
per WPC in a short amount of time with any thunderstorm remains
valid as well.
The Simulated High Resolution Composite Reflectivities in decent
agreement with developing pockets of showers/thunderstorms from
Williston south to Bowman, which is in line with the current
Regional Radar. The Non-Supercell Composite Index is between 1
and 2 over northwest ND. Will need to monitor the low level lapse
rates and surface vorticity for any potential landspouts that
could develop within this area.
Scattered showers and thunderstorms continue through the evening,
then shift away from southwest ND towards midnight. As mentioned
above, concur with fog southwest and south central given the
moisture, and crossover temperatures being met later tonight per
BUFKIT soundings.
.LONG TERM...(Sunday night through Saturday)
Issued at 248 PM CDT Sat Aug 12 2017
A mid level transitory shortwave ridge shifts into eastern MT and
western ND Sunday, behind the departing upper low. Increasing
sunshine west Sunday morning, with clouds decreasing in the
afternoon in the central. Lingering precipitation over the James
River Valley Sunday morning, diminishes through 18z Sunday before
ending. Highs in the 70s.
The next in a series of shortwaves moves into eastern MT and
western ND Monday with a chance for showers and thunderstorms.
Additional shortwaves traverse through a southwest flow aloft
Monday night through Tuesday night affecting western and central
ND with showers and thunderstorms. A break on Wednesday with
another shortwave slated for Thursday/Thursday night. Highs in the
upper 70s to lower 80s Monday through Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued
at 710 PM CDT Sat Aug 12 2017
Main hazards to aviation include widespread thunderstorms along
and south of I-94 Saturday evening. After the Thunderstorms
diminish Saturday night abundant low level moisture will support
MVFR-IFR conditions in low ceilings and fog KDIK-KBIS-KJMS
09-15Z. Otherwise VFR.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...WAA
SHORT TERM...KS
LONG TERM...KS
AVIATION...TWH
Area Forecast Discussion
National Weather Service Denver/Boulder CO
756 PM MDT Sat Aug 12 2017
.UPDATE...
Issued at 747 PM MDT Sat Aug 12 2017
Strong storms moving out of our area so the Severe Thunderstorm
Watch has been cancelled. Upstream showers/storms will mostly die
as they move in. Some potential for some light showers from the
convective remnants moving across from western Colorado. This will
also keep a fair amount of cloud cover around much of the night,
so the prospect for low clouds and fog late tonight is still
questionable.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 242 PM MDT Sat Aug 12 2017
Scattered thunderstorms over Weld County spurred on by a passing
short wave to the north. Activity will continue to spread east
southeast across the northeast plains where CAPES are around 2500
j/kg at this time. Large hail and damaging winds the main threat
along with locally heavy rainfall. Scattered thunderstorms with
brief heavy rain and small hail moving across northern Jefferson
County. HRRR keeps the thunderstorms active through this evening
with diminishing activity after midnight. Severe Thunderstorm
Watch 449 in effect until 2300 mdt for Morgan, Logan, Washington,
Logan, Sedgwick and Phillips counties. On Sunday the ridge will be
a little stronger, but the flow aloft will remain northwesterly
aloft. Shear not as strong, but sufficient CAPE over the northeast
plains to support marginal risk for storms. Forecast soundings
yield CAPES from 1300-2300 j/kg east of the urban corridor,
highest over the northeast corner. Some patchy fog possible
overnight for the plains may make its way into the Denver area by
12z.
.LONG TERM...(Sunday night through Saturday)
Issued at 242 PM MDT Sat Aug 12 2017
The zonal flow pattern is expected to continue for a few more
days, with enough moisture lingering over the state to produce
afternoon and evening thunderstorms. The continuing moderate
westerly flow aloft will keep storms moving along. Models do not
pin point any particular day with heavier rain, so it is difficult
to say any day will have flooding problems. After Wednesday, the
GFS and ECMWF show stronger upper level ridging building over the
western U.S. which will start to dry things out across Colorado.
This will result in Thursday and Friday being the driest days of
the week. Temperatures will remain around seasonal normals through
the forecast period. Locally heavy rain will be the primary threat
from each afternoon of shower activity.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 747 PM MDT Sat Aug 12 2017
VFR conditions are expected to prevail through Sunday. There is a
chance that there will be areas of fog with localized IFR
conditions between 10z and 15z. Slight chance of a thunderstorm
Sunday after 21z with variable winds gusting to 30 knots.
&&
.BOU WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Gimmestad
SHORT TERM...Cooper
LONG TERM...Dankers
AVIATION...Gimmestad
Area Forecast Discussion
National Weather Service Taunton MA
1109 PM EDT Sat Aug 12 2017
.SYNOPSIS...
Unsettled weather this evening as a cold front moves through
tonight. High pressure brings dry weather Sunday and Monday. A
cold front swings through the region Tuesday night. Low pressure
passes just offshore on Friday and early Saturday.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Only minor tweaks to the forecast this evening. Monitoring
flooding risk across portions of northwest MA. Still expecting a
cold front to move across our region overnight.
7 PM update...
Southwest flow aloft continues. Cold front over Central NY and
PA moves east. Radar shows tstms across Eastern NY and Southern
VT moving northeast. One storm south of Albany is trending
toward the NW corner of Mass and may cross part of western
Franklin County between 730 pm and 8 pm. HRRR forecast is a
little slower, but does show potential for tstms in NW Mass
between 8 and 9 pm. The HRRR brings the line to Orange and
Springfield around 11 pm, but shows a weakening trend by that
time. The showers quickly fade out shortly after that.
We have made a few small adjustments to the pops but remain
close to the previous forecast. Main concern will be one or two
heavy downpours, as PW values are around 1.5 inches.
No change in the outlook for low clouds and fog, or for
temperatures.
Previous discussion...
Cold front will push through the region tonight. Lingering showers
and possible storms may push through into the interior but the
overall coverage of any precip will be limited. A few spot showers
are also possible across the Islands overnight in a difluent region,
but confidence is a bit lower. Therefor continued to mention a
chance for showers for that region overnight.
Aside from precip chances, the biggest issue will be fog and
stratus. If today was an indicator anticipate widespread stratus and
fog across the region tonight. Higher dewpoints continue to advect
into the region ahead of approaching cold front resulting in a low
temp/dewpoint spread. Highest confidence in low vsbys is across the
eastern half of the region. However held off on dense fog advisory
as gusty winds overnight may keep vsbys from remaining below 1/4 of
a mile. Regardless, it will be slow going overnight for any
travelers.
Once the front passes through from west to east, winds will switch
to a more westerly direction. This will bring in dry air and lift
the fog quite quickly. Best chance for this is across the CT valley
and into central MA before sunrise.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
Sunday and Sunday night...High confidence.
Cold front will be offshore by Sunday morning. Southwest flow aloft
will turn more to the northwest as upper level trough axis moves
through. This will allow for some weak CAA during the day, but
moreso dry air will push into the region. Despite the CAA aloft,
temps will be warmer than today with temps in the low to mid 80s.
Steepening lapse rates with some low level moisture will aid in the
development of diurnal cu during the day. Otherwise dry weather will
prevail with breezy west winds around 15 to 20 MPH.
Clearing skies and light winds will remain over the region Sunday
night thanks to building high pressure. Radiational cooling will
occur resulting in temps to fall into the mid to upper 50s. Metro
regions of PVD and BOS will remain slightly warmer, closer to the
mid 60s. Some patchy fog may develop in the typical low lying
regions, but will not be widespread.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Big Picture...
A pair of shortwaves will move across the northern tier of the USA
this period. One shortwave, currently over the Northern Plains,
crosses New England later Tuesday. The second shortwave, currently
offshore of British Columbia, arrives here at the end of the week.
Model mass and thermal fields are similar through early Wednesday,
then diverge. Thus, higher than average confidence Monday and
Tuesday followed by diminishing confidence mid to late week.
Details...
Monday...High confidence.
High pressure moves overhead. With light flow, this will allow sea
breezes to develop along the coast. Temperatures at 850 mb will
be around +16C, which would support max sfc temps in the mid 80s.
Fair skies and light winds should allow areas of fog to develop
Monday night, especially across the CT River Valley. Dew points of
55-65 should allow a similar range of min temps Monday night.
Tuesday...Moderate confidence.
A shortwave crosses New England during the day. Models show a
surface trough crossing the region at this time, but thickness
fields show little change in airmass, so this is probably not an
actual cold front. Moisture fields show precipitable water values
around 1.25 inches, not exceptional for August. Cross-sections show
the moisture is limited in extent, mostly below 700 mb. Stability
parameters are fine, with totals in the upper 40s and lifted index
sub-zero. Models also show a theta-e ridge moving along with the
trough. With these mixed signals, we will indicate low-end chance
pops for the afternoon/evening. Otherwise a fine day with 850 mb
temps 15-16C supporting sfc high temps in the mid 80s.
Wednesday...Moderate confidence.
Northwest flow aloft will push a cold front through the region.
Airmass will be dry, so no showers expected. More likely a wind
shift out of the north or northeast. Temps aloft still support max
sfc temps in the 80s.
Thursday...Moderate confidence...
Fair weather during the day as high pressure departs to the east. A
warm front approaches from the west, and this should bring
increasing mid and high clouds. Still plenty of dry air near the
ground, so no precip expected during the daytime hours.
Thursday night through Saturday...Low-moderate confidence.
Clouds lower and thicken Thursday night with a deep column of
moisture over New England. The deep column lingers through Friday.
Low pressure at the surface moves along the approaching warm front.
The 12Z suite of models is showing this low moving along or just
south of the New England coast, keeping our area in a moist east
flow. Expect clouds and rain/showers Thursday night and Friday.
Friday-Saturday...Low pressure moves across from the Great
Lakes. GFS redevelops the low south of New England Friday, then
moves it east of the region Saturday. This would keep us in an
easterly flow, bringing clouds and rain. Potential for leftover
showers on Saturday...an onshore flow lingers in Eastern Mass
with lingering moisture below 700 mb, but drying air above that
level.
&&
.AVIATION /03Z SUNDAY THROUGH THURSDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Sunday Night/...
Tonight...Moderate confidence.
Mixed VFR/MVFR to start, dropping to IFR. LIFR is possible
across the eastern MA and RI terminals. A shower/tstm is
possible from 00Z to 06Z mainly in NW Mass. Conditions will
improve from west to east after 06z as winds shift from the
south to a more WNW direction.
Sunday...High confidence. VFR. Breezy W winds near 15-20 kts.
Sunday night...High confidence. Mainly VFR. Patchy MVFR fog possible
in low lying terminals.
KBOS Terminal...High confidence in trends.
KBDL Terminal...High confidence in trends. Spot shower/storm is
possible after 01z.
Outlook /Monday through Thursday/...Moderate confidence.
VFR most of the period. Areas of IFR cigs/vsbys in early morning fog
Monday and Wednesday. Afternoon sea breeze Monday along the coast.
Brief MVFR cigs/vsbys in showers and t-storms Tuesday
afternoon/evening.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Short Term /through Sunday Night/...High confidence.
Southerly flow will continue tonight allowing for winds to
strengthen just a bit ahead of approaching cold front. A few gusts
near 20 kts is possible. This will help increase seas to above 5
feet tonight and into tomorrow especially across the southern
waters. High pressure building late in the day on Sunday and
especially Sunday night will help relax seas below SCA.
Aside from wind and seas, vsbys will once again be an issue for
tonight. Anticipate widespread fog with vsbys below 1SM. Conditions
will lift by Sunday morning as cold front moves well offshore.
Outlook /Monday through Thursday/...Moderate confidence
Winds and seas will remain below Small Craft Advisory levels through
the period. Low pressure passing well offshore may spread light rain
into the southern waters Monday and Tuesday. There may be some vsby
restrictions in showers Tuesday, and in fog on Monday and Tuesday
nights.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 2 AM EDT Monday for ANZ254-255.
Small Craft Advisory from 5 AM to 8 PM EDT Sunday for ANZ235-
237.
Small Craft Advisory until 11 PM EDT Sunday for ANZ256.
&&
$$
SYNOPSIS...WTB/Dunten
NEAR TERM...WTB/Belk/Dunten
SHORT TERM...Dunten
LONG TERM...WTB
AVIATION...WTB/Dunten
MARINE...WTB/Dunten
Area Forecast Discussion
National Weather Service Caribou ME
924 PM EDT Sat Aug 12 2017
.SYNOPSIS...
A weak frontal boundary will bring some showers and thunderstorms
across the area tonight with some fog. A cold front will cross
the region Sunday with another round of showers and thunderstorms,
followed by high pressure on Monday.
&&
.NEAR TERM /THROUGH SUNDAY/...
9:24 PM update...Watching an area of thunderstorms on radar
coming out of the western mountains. The activity has been
bowing out and will need to be watched, but it likely will
weaken as it moves toward southern Piscataquis County. Some of
this activity will likely work across central potions of the CWA
very late this evening. There is another storm that is quite
strong that we are watching in Quebec to the west of Aroostook
County that will also likely weaken before it reaches the CWA,
but bears close watching. There may not be much additional
shower or thunderstorm activity behind this until the cold front
comes through Sunday afternoon. Made some adjustments mainly to
the PoPs based on the latest radar and near term model trends.
Also added in some gusty wind until midnight across the western
zones as any of the stronger convection could produce some wind.
Previous discussion...
Scattered thunderstorms overnight with another round expected
for Sunday.
Showers and tstms setting up over w and nw areas as s/wv lifts
up across the region from the NYS region. Some lighter showers
were seen on radar lifting up across the region from the s. The
latest SPC meso analysis showed best CAPE and lapse rates
residing across the w and nw into early evening. Some of the
stronger storms across the wnw could contain strong wind gusts
and hail. First batch of activity is shown by the latest HRRR
and RAP to diminish after 8 pm. Some fog is expected to set up
later in the evening into the overnight hrs. Decision was to hit
the downeast and western areas hardest w/the fog and went
patchy fog elsewhere. A second round of activity is slated to
develop across the region overnight into early Sunday morning as
the cold front apchs from Canada. There appears to be a
pre-frontal boundary that moves across the region which could
allow for some convection to fire back up well after midnight
into the daybreak hrs. The RAP and GFS show elevated
instability as far e as BGR and BHB into Sunday morning. The NAM
is weaker as is the HRRR. There does look to be elevated CAPE
of 600-800 joules w/0-6km shear apchg 30 kts. So, if storms do
fire, some could have some gusty winds. Decided to carry tstms
into the Downeast, but w/stable layer in place, confidence is
low to have enhanced wording. The evening crew can assess this
further.
For Sunday, SPC has placed the entire region in a Marginal Risk
for a few tstms to become severe. This will be a challenge as
there could some action in the morning w/the pre-frontal
boundary and then the short range guidance shows a second
round across northern areas by late morning into the early
afternoon. Instability parameters such CAPE(700-1000 joules) and
0-6KM shear of 30 kts favor organized potential. Lapse rates do
look as though they steepen by later morning especially in the
mid levels to allow for updrafts. Given this, added the mention
of strong wind gusts and hail to the forecast. Stayed close to
the midnight crew`s assessment of 70s w/the warmest temps across
the central and downeast areas.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
Expect clearing skies Sunday night behind the departing cold
front and mainly sunny skies on Monday. Lows Sunday night will
range from the upper 40s to lower 50s. Highs on Monday will
range from the mid to upper 70s north and upper 70s to near 80
central and down east. Expect fair weather Monday night in
advance of an approaching cold front. Lows Monday night will
range from the mid to upper 50s across the region. Tuesday will
see a chance for showers and thunderstorms as a cold front
begins to cross the region. Highs on Tuesday are expected to
range from the mid 70s to near 80, except cooler along the
coast.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
A few showers may linger into Tuesday evening, followed by
partial clearing Tuesday night. A secondary front/trof will
cross the region on Wednesday. This feature combined with a pool
of cold air aloft, will once again result in the chance for
showers, mainly during the afternoon. Thursday and Friday are
looking like a mainly dry days, as latest model runs are
suggesting the late week system may stay off to our south, as
confluent flow aloft allows for more in the way of high pressure
to build build in from the north. The dry weather may hold into
the beginning of next weekend if the system remains to our
south. Daytime high temperatures through the long term are
expected to be at, or even a bit below normal for this time of
year.
&&
.AVIATION /01Z SUNDAY THROUGH THURSDAY/...
NEAR TERM: VFR and MVFR this evening. It does look like all
terminals will be seeing conditions drop to IFR w/the potential
for LIFR from HUL down to KBGR and KBHB. Fog will be a nuisance
overnight w/the threat for a tstm. IFR/LIFR Sunday morning
gradually improving to MVFR by later morning w/another round of
tstms. Looking for conditions to go to VFR by later Sunday
afternoon into evening.
SHORT TERM: Generally VFR through the period, except in any
afternoon scattered showers and thunderstorms Tuesday and
Wednesday, which may result in briefly lower conditions. Could
also see the potential of lower clouds and stratus making their
way into the vicinity of the Bar Harbor airport later Monday
night into Tuesday morning with local IFR conditions possible.
&&
.MARINE...
NEAR TERM: No headlines. The biggest issues will be the fog
tonight into early Sunday which could hamper navigation. Tstms
are a threat as well. SSW winds are expected to increase ahead
of the cold front on Sunday to 10-15 kts. This will allow seas
to build some but they will remain below 5 ft. Decided to add
some gusts to 20 kts for the outer zones.
SHORT TERM: Winds/seas are generally expected to remain below
small craft advisory levels through the period.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...CB/Hewitt
Short Term...Duda
Long Term...Duda
Aviation...CB/Hewitt/Duda
Marine...CB/Hewitt/Duda
Area Forecast Discussion
National Weather Service Dodge City KS
613 PM CDT Sat Aug 12 2017
...UPDATE TO AVIATION...
.SHORT TERM...(This evening through Sunday)
Issued at 302 PM CDT Sat Aug 12 2017
Scattered weak showers persisted this morning and continues into
the afternoon, despite relative weak mid level lapse rates. More
impressive low level lapse rates farther west may be the narrow
zone where a few non severe thunderstorms develop this afternoon,
aided by weak vorticy advection rotating through the panhandles
and western Oklahoma. As any forcing becomes quickly removed from
the area this evening precipitation chances should dwindle with
time. Some convective allowing models develop one or more mcs
clusters from ne Colorado into northwest Kansas during the
overnight. In most cases the models suggest the convection decays
as it reaches the west central Kansas counties. As such pops will
be ramped up modestly overnight, as well as an introduction of fog
across the southwest where widespread low stratus should quickly
redevelop. HRRR is the most aggressive model with respect to
thunderstorms early Sunday in the far western counties and may be
overdone when considering the other CAMS. Additional development
Sunday would be contingent on how fast the stratus might be mixed
out if at all. The NAM develops no convective precipitation at
this time.
.LONG TERM...(Sunday night through Saturday)
Issued at 302 PM CDT Sat Aug 12 2017
A relatively cool period continues through the extend, although
temperatures begin to revert back toward normal climatological
highs by mid week and beyond. Probability for precipitation should
remain low though mid week in the absence of any significant
lift/forcing. However by wednesday the models begin to carve out a
western/Intermountain upper trough which should lend itself to
eject shortwave energy into the Central Plains region. Western
Kansas will have precipitable water values within the 90% moving
average, conducive for MCS maintenance any given period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 612 PM CDT Sat Aug 12 2017
Low level stratus will prevail/redevelop across much of southwest
Kansas tonight resulting in MVFR cigs in the vicinity of KGCK, KLBL,
and KDDC. KHYS could see MVFR cigs toward daybreak Sunday morning
while the remaining TAF sites could possibly see IFR cigs. High
relative humidity and very light southeast winds could result in
areas of fog development late tonight with MVFR vsbys possible.
Light southeast winds will persist through early Sunday as surface
high pressure remains locked in across the Upper Midwest.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 63 82 66 87 / 20 20 20 20
GCK 63 81 65 88 / 20 20 30 20
EHA 63 82 63 87 / 20 20 30 20
LBL 63 81 66 88 / 20 20 30 20
HYS 62 82 66 88 / 10 10 10 10
P28 64 83 68 87 / 30 20 20 30
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Russell
LONG TERM...Russell
AVIATION...JJohnson
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
655 PM CDT Sat Aug 12 2017
.AVIATION...
Mostly clear skies through the evening. May start to see a little
more cirrus come in from the west as convection continues west and
northwest of the Hill Country. Main question overnight will be if
MVFR ceilings develop once again Sunday morning. MOS guidance does
not paint a very robust picture of having widespread morning
cloudcover. Latest RAP and HRRR runs show a swath of drier air moving
in from the south overnight which may in fact hamper any low cloud
production. Want to see more run to run consistency in the models
before the inherited MVFR ceilings are removed for AUS/SAT/SSF. So
in the meantime I have taken the prevailing MVFR for Sunday morning
and have dropped it to a TEMPO group to show a downward trend in
probabilities and confidence. The 00Z model runs hopefully will show
a continued trend. Sunday mid morning through afternoon should be
VFR with high pressure dominating. Wind from the south should remain
below 15kt.
&&
.PREV DISCUSSION... /ISSUED 200 PM CDT Sat Aug 12 2017/
SHORT TERM (Tonight through Sunday Night)...
The mid and upper level ridge will remain in place across south
central Texas through Sunday night. Look for continued hot and dry
weather, with hazardous afternoon heat index values across the
coastal plains east of Interstate 35. Will let the overnight shift
refine the hottest area and issue a heat advisory for Sunday.
LONG TERM (Monday through Saturday)...
No major change in forecast model trends, we still expect a
weakening of the upper level ridge by mid-week, with a trough moving
through the central Great Plains as a source of lift late Tuesday for
Val Verde County, and on Wednesday for the rest of the area. Even
with the tail end of the trough, overall moist air content and
instability will be low enough for only 20 percent PoPs.
A new ridge develops over Texas at the end of the week into early
the next week. While this ridge will suppress cloudcover and make
for great solar eclipse viewing on Monday, August 21st, it also
means most locations will remain dry, so continue watering plans in
accordance with local restrictions.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 77 101 77 100 77 / 0 0 0 0 0
Austin Bergstrom Intl Airport 76 100 76 99 76 / 0 0 0 - 0
New Braunfels Muni Airport 76 100 75 101 76 / 0 0 0 0 0
Burnet Muni Airport 75 98 74 97 74 / 0 0 0 0 0
Del Rio Intl Airport 78 104 78 102 79 / 0 0 0 0 0
Georgetown Muni Airport 77 99 76 98 76 / 0 0 0 0 0
Hondo Muni Airport 75 102 75 102 75 / 0 0 0 0 0
San Marcos Muni Airport 76 100 76 99 76 / 0 0 0 0 0
La Grange - Fayette Regional 77 100 77 99 77 / 0 0 0 10 0
San Antonio Intl Airport 77 100 77 101 77 / 0 0 0 0 0
Stinson Muni Airport 76 100 76 100 77 / 0 0 0 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
Heat Advisory until 7 PM CDT this evening for the following
counties: Atascosa...Bastrop...Caldwell...De Witt...Fayette...
Gonzales...Guadalupe...Karnes...Lavaca...Lee...Wilson.
&&
$$
Mesoscale/Aviation...09
Synoptic/Grids...Allen
Public Service/Data Collection...Treadway
Area Forecast Discussion
National Weather Service Grand Forks ND
950 PM CDT Sat Aug 12 2017
.UPDATE...
Issued at 948 PM CDT Sat Aug 12 2017
Based on current radar trends and guidance from the HRRR have
trimmed back on pops across the north through midnight. Still
unsure of coverage across the north as upper low drops through so
maintain low pops later tonight. The far s-se will see a break
until the next band moves in aft midnight.
UPDATE Issued at 654 PM CDT Sat Aug 12 2017
Trimmed pops over the DVL basin where returns are having a tough
time staying organized. Otherwise forecast on track at this point.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 250 PM CDT Sat Aug 12 2017
Main challenge for the short term will be heavy rain potential
across the south. In general models continue to push south the
heaviest precip into northeastern SD and southwestern
MN...although Grant County up into Otter Tail county still seeing
potential for one to one and a quarter inch of rain fall.
Elsewhere looking at one half to an inch of rain along and south
of the I-94 and Highway 10 corridor.
Upper low over w cntrl ND will drop into the southern valley by
12Z Sun as an inverted trough associated with sfc low pressure
over far s cntrl SD extends NE into sw/w central MN. A 35 to 45
kt low level jet will push north into the Watertown SD/Madison
MN area...with the heaviest precip amounts per 12Z NAM being along
a Watertown SD to Morris MN axis on the nose of the llj. This
heavier precip band is further south than prev forecast hence
slightly lower amounts across southern zones. Showalters increase
to positive roughly north of Fargo and generally keeping showery
activity with isold thunder for p-type overnight. Main precip ban
on Sunday then moves into the Alexandria area during the morning
and on into Brainerd in the aftn...with the NW edge clipping my
far sern zones where storm total QPF values exceed an inch due to
the longer duration of precip over this area. Overnight lows
tonight in the mid 50s and the coolest Sunday highs over the
southeast, where rain and isold thunder will limit daytime highs
to the mid 60s. Areas across the north will reach the upper 70s
with more solar available.
.LONG TERM...(Sunday night through Saturday)
Issued at 250 PM CDT Sat Aug 12 2017
(Sun night - Tue)
Short wave will exit the area by Monday, followed by a weak bubble
of high pressure that will prevail during the daylight hours. The
next system will begin to affect the western FA by late Monday
night. Timing differences exist between the GFS and the ECMWF with
the latter being much quicker initiating convection during the
morning on Tue. Given that the GFS is usually the faster model and
this time is more laggard, believe that we`ll favor it with a slower
solution this time.
(Wed-Sat)
CAPE values will be modest overnight Tue into Wed (still favoring
the souther forecast area) but stronger low level forcing in the
vicinity of frontal boundary should yield areas of shwrs/tstms with
particular focus farther south. The GFS slowly moves the main upper
trough through the area Wednesday and Wednesday night, bringing more
precipitation to MN during this time. The next precipitation
opportunity will present itself on Fri as a healthy wave traverses
the Northern Plains. Temperatures throughout the upcoming week
should stick very close to mid August averages.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 654 PM CDT Sat Aug 12 2017
Best shower potential will be over the FAR site where tempo/vcsh
groups added. Elsewhere potential looks limited at this point as
rain having a tough time holding together much north of I94.
General VFR cigs/vsby through most of the period. Some indications
of mvfr cigs over the west and south tomorrow morning.
&&
.FGF WATCHES/WARNINGS/ADVISORIES...
ND...None.
MN...None.
&&
$$
UPDATE...Voelker
SHORT TERM...Speicher
LONG TERM...WJB
AVIATION...Voelker
Area Forecast Discussion
National Weather Service Flagstaff AZ
327 PM MST Sat Aug 12 2017
.SYNOPSIS...Expect typical monsoon weather conditions through the
weekend. Drier air will bring a decreasing trend in storms
beginning Monday, with isolated storms from Tuesday onward.
&&
.DISCUSSION...Active afternoon across northern Arizona with
scattered storms and isolated very heavy rain. Small hail was also
reported. HRRR does show storms continuing through the night
moving from west to east across Coconino County into central
Navajo and Apache Counties.
Low level moisture remains plentiful across northern Arizona
through Sunday. The steering flow will push storms toward the
E-NE. Fairly slow storm motion will bring a chance of localized
heavy rainfall/flooding. Hail and gusty winds will also accompany
the stronger cells.
On Monday, a trough of low pressure will move out of the Pacific
Northwest into the Great Basin. This will push monsoon moisture
east of Arizona and will bring drier are over the state. Storm
chances will drop to the slight chance category for most areas.
By Tuesday, further drying is expected as the trough moves across
Arizona. Breezy to windy southwest winds will also develop on
Monday and Tuesday. Near average daytime temperatures should
persist through at least Friday.
&&
.AVIATION...For the 00Z package...Scattered showers and
thunderstorms will continue through the afternoon and evening across
northern AZ, with localized MVFR/IFR conditions in the strongest
storms. Storm coverage and intensity will decrease after 03Z, with
redevelopment expected during the daylight hours Sunday. Aviation
discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Daily rounds of showers and thunderstorms
will continue through Monday, with temperatures slightly below
normal.
Tuesday through Thursday...A drier air mass will move back into the
region with significantly decreased storm chances.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...MAS
AVIATION...KD
FIRE WEATHER...KD
For Northern Arizona weather information visit
weather.gov/flagstaff
Area Forecast Discussion
National Weather Service GRAND JUNCTION CO
952 PM MDT Sat Aug 12 2017
.SHORT TERM...(Tonight through Sunday night)
Issued at 334 PM MDT Sat Aug 12 2017
Some light showers lingered across the north this morning with
plenty of sun to work on the moisture in place to fire storms over
all higher terrain this afternoon. Seems a bit more active this
afternoon than yesterday, with convection blossoming across
eastern Nevada, Utah and northern Arizona. This convection to the
west is associated with a shortwave that will be tracking through
the region this evening and overnight. Pretty much all the near
term models are indicating some form of storm activity continuing
through the overnight hours tonight with the HRRR picking up on
this activity fairly well. Storms are expected to increase across
eastern Utah late this afternoon and move into western Colorado
this evening with the east-central Utah and west-central Colorado
corridor being favored for overnight convection through the early
morning hours on Sunday. Increased PoPs as a result as confidence
is a bit higher due to model consistency picking up on this
shortwave with the NAMNest picking up on this activity in
yesterday`s model runs. This shortwave disturbance and storm
activity also comes with an increase in precipitable water (PW)
values above an inch for most areas with pockets of 1.25 near the
Four Corners. Expect some lingering isolated to scattered showers
after sunrise Sunday over the eastern zones as this shortwave
progresses eastward. Overnight lows were much cooler the last
couple nights than model guidance suggested, due to the rain-
cooled air from evening and overnight shower activity. Lowered
low temperatures tonight as a result.
Convection is expected to re-fire across the higher terrain
Sunday afternoon as sufficient moisture and enough instability
remains in place with storm activity drifting into valleys late
afternoon and evening as another shortwave tracks across. Expect a
similar day on Sunday like today (Saturday). Storms both days
will be capable of heavy rainfall, frequent lightning, gusty
outflow winds of 40 to 50 mph and some small hail as decent shear
exists for some sustainable updrafts. Most storm activity should
wind down after midnight Sunday night as no distinguishable
shortwave moves through. Cannot completely rule out overnight
convection though so kept some isolated mention in the forecast
for some areas.
.LONG TERM...(Monday through Saturday)
Issued at 334 PM MDT Sat Aug 12 2017
Southwest flow will increase Monday as an upper level trough
deepens over the western states into the Desert Southwest. Good
upper level support exists with the upper level jet to the west
over Utah, so expect a fairly active day on Monday with storm
development. One concern is that some drier air tries to work into
the Four Corners region with this trough. However, plenty of
moisture will remain for storms to fire and become widespread with
strongest storms to fire along the moisture gradient. This
slightly drier air may help to increase instability in the
atmosphere for stronger storms. Activity looks to increase Monday
evening as a leading shortwave moves through the flow for
convection to continue overnight into Tuesday morning. The upper
level trough and associated cold front moves through on Tuesday,
allowing for a fairly active day. Due to the low dew point
depressions, remnant moisture and forcing in place, raised
chances and coverage of storms Monday through Tuesday. Expecting
these to be the most active days.
Cooler air moves in behind this trough with drier air as well. The
pattern overall looks to favor a drying trend from mid-week
through the end of the week for a downturn in storm activity.
Thinking that enough moisture will still hang around for daily
afternoon convection over the higher terrain with most lower
elevations drying out and slowly warming up towards the end of the
week from near normal/slightly below normal values towards
slightly above normal.
&&
.AVIATION...(For the 06Z TAFS through 06Z Sunday night)
Issued at 952 PM MDT Sat Aug 12 2017
Scattered showers and thunderstorms will continue across eastern
Utah and western Colorado through 10Z tonight and come to an end
shortly after sunrise Sunday. Another round of storms will develop
after 16Z Sunday and persist well into the evening hours as a
disturbance treks through the region. As has been the trend the
past couple of days, heavy rain, gusty and erratic winds to 45
kts, small hail and frequent lightning will accompany the
strongest storms. Expect ILS breakpoints to be met in the vicinity
of showers with mountains tops occasionally obscured.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
SHORT TERM...MDA
LONG TERM...MDA
AVIATION...TGJT
Area Forecast Discussion
National Weather Service Green Bay WI
1042 PM CDT Sat Aug 12 2017
Updated aviation portion for 06Z TAF issuance
.SHORT TERM...Tonight and Sunday
Issued at 224 PM CDT Sat Aug 12 2017
The latest RAP analysis and satellite/radar imagery show high
pressure centered over the northern Mississippi Valley early this
afternoon. Skies are mostly clear to partly cloudy across the
region, with only high based cu present. Looking upstream,
shortwave troughing is slowly moving east over the northern Plains,
with scattered showers and storms over the Dakotas. As this
shortwave moves east, clouds and temps are the main forecast
concerns.
Tonight and Sunday...Once the high based cu dissipates, high
pressure will provide mostly clear and quiet conditions for much of
the night. Will start to see cirrus move into north-central WI late
tonight ahead of the shortwave. But the cirrus should not hold up
temps much, so will continue to side with the colder guidance for
lows. Min temps should range from the lower to mid 40s in the cold
spots to mid 50s near the Lake.
Mid and high clouds will continue to increase across the region
through the day as the shortwave energy arrives from the west. It
will run into a much drier airmass below 600-700mb, as deeper
moisture will remain west of the region. But combined with some
high based cu once again, should see skies turn partly sunny to
mostly cloudy after a relatively sunny start. Temps will be near
todays readings, perhaps a degree warmer.
.LONG TERM...Sunday Night Through Saturday
Issued at 224 PM CDT Sat Aug 12 2017
Return flow behind departing surface high will bring increased low-
level moisture to area late Sunday and Monday. Weakening
shortwave trof will move across the state Monday with attendant
shower/storm chances.
Energetic jetstream over north Pacific undercuts block over
central Canada with another shortwave trof moving into Upper
Midwest late Tuesday-Wednesday. Models in general agreement on
this scenario, although GFS is a bit more aggressive with
convection. Yet another shortwave trof moves in later in the week
as Pacific energy continues to generate fast-moving systems. GFS
again a bit stronger with late-week system.
Temperatures should generally be near or above normal during the
upcoming work week.
&&
.AVIATION...for 06Z TAF Issuance
Issued at 1042 PM CDT Sat Aug 12 2017
Mostly clear skies expected tonight, with ground fog
possible for a few hours around sunrise. VFR conditions forecast
Sunday with middle and high clouds arriving from the west.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......JKL
AVIATION.......RDM
Area Forecast Discussion
National Weather Service Northern Indiana
647 PM EDT Sat Aug 12 2017
.SYNOPSIS...
Issued at 219 PM EDT Sat Aug 12 2017
High pressure will build into the Great Lakes tonight and linger
through early next week providing fair weather. Temperatures will
be cooler than normal over the weekend, with a slow warming trend
early next week. The high will move to our east by the middle of
next week allowing moist southerly flow to return. A low pressure
system moving east from the plains will interact with this
moisture providing a good chance for showers and thunderstorms
around Wednesday night or Thursday.
&&
.SHORT TERM...(This Evening through Sunday)
Issued at 219 PM EDT Sat Aug 12 2017
Shortwave dropping south through the flow stirring up some
showers across eastern portions of Michigan. HRRR suggests as this
drops into mainly NE areas some isolated showers could form.
Given trends updated earlier for token 20 pop for a few hours
before rapid decrease in pops. Clearing skies and diminishing
winds may set the stage for some patchy fog overnight, but
boundary layer moisture may be low enough to keep fog from
developing. Will punt to eve shift to monitor trends.
No sensible weather concerns Sunday with little more than fair
weather cu mainly SE during peak heating. Below normal
temperatures will persist with highs in the middle to upper 70s.
&&
.LONG TERM...(Sunday Night through Saturday)
Issued at 219 PM EDT Sat Aug 12 2017
Dry weather to persist through at least Tuesday night with models
still varying on exact timing of series of waves starting as early
as Weds afternoon into Friday. Highest pops still appear to be in
the Wed ngt/Thurs window, but somewhat skeptical if likely pops
will work out. Have maintained general consensus for now.
Temperatures will head back towards more normal or somewhat above
normal levels with increasing humidity towards the second half of
the week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday Evening)
Issued at 645 PM EDT Sat Aug 12 2017
Boundary layer moisture combined with light winds will favor
patchy ground fog to form over the southern two thirds of the
forecast area around 10Z-14Z. This will mainly affect the FWA TAF.
Otherwise VFR conditions prevail.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Beach Hazards Statement until 10 PM CDT this evening for INZ003.
MI...Beach Hazards Statement until 11 PM EDT this evening for MIZ077.
OH...NONE.
LM...Small Craft Advisory until 11 PM EDT this evening for LMZ043-046.
&&
$$
SYNOPSIS...JT/Fisher
SHORT TERM...Fisher
LONG TERM...Fisher
AVIATION...Lewis
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Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
1103 PM CDT Sat Aug 12 2017
.UPDATE...
Issued at 1059 PM CDT Sat Aug 12 2017
Updated forecast to drop severe thunderstorm watch. Decreased
chances for precipitation over night.
UPDATE Issued at 413 PM CDT Sat Aug 12 2017
Updated zones to add severe thunderstorm watch.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 249 PM CDT Sat Aug 12 2017
The HRRR would seem to be the most rational model for the storm
activity late this afternoon and tonight. A blend of the Canadian,
nam and gfs was the basis for chance showers and thunderstorms
Sunday.
Storm activity late this afternoon and tonight could organize into 3
clusters off the Colo front range, Laramie range and Black
Hills/White river valley where a warm front will be located. A blend
of the HRRR and HRRR Exp models was the basis for the storm forecast
tonight. The RAP model was taking an atypical storm/propagation
southwest from Valentine to Imperial and was discarded for this
forecast.
POPs are limited to 70 percent as some models like the NAM show the
infamous "Lincoln County Split" sending storms through Southwest
Nebraska and North Central Nebraska north of Broken Bow. This would
produce little or no rain across Lincoln and Custer Counties.
Storm activity should exit the forecast area 12z-15z Sunday morning
but redevelopment is possible across Wrn and Ncntl Nebraska. This is
highly dependent on the tracks of the MCS`s tonight. So, POPs Sunday
are limited to 30 percent. SPC is placing a slight risk for severe
storms across the Nebraska Panhandle for isolated storm development
during the afternoon. Winds aloft at 500mb should increase to 30-
40kt late in the afternoon.
Temperatures aloft are quite cold today and Sunday, less than 10C at
700mb, and when combined with 30 to 40 kt winds at 500mb and ample
moisture, SPC suggested very large hail west of highway 83 late this
afternoon and this evening. See the SPC day 1 outlook for additional
information.
South winds redevelop Sunday and this, presumably, will support
highs in the lower 80s with partly cloudy skies.
.LONG TERM...(Sunday night through Saturday)
Issued at 249 PM CDT Sat Aug 12 2017
The long term forecast period will be characterized by near to
slightly below temperatures and a chance for at least isolated
thunderstorms daily. By far the best chance for organized widespread
thunderstorm activity will be Tuesday evening, when a strong
shortwave trough will move east across the Dakotas and Nebraska. A
few severe storms will probably occur, but overall shear is rather
weak. The bigger threat may be areas of locally heavy rainfall.
Really little pattern chance seen this week...as west to northwest
flow materializes once again in the wake of Tuesday`s shortwave. The
upper level high pressure and associated heat will remain well south
of our region in TX and LA.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 631 PM CDT Sat Aug 12 2017
Thunderstorms continue along aand south of a line from KVTN to
KAIA. These storms contain large hail. KVTN looks to be on the
backside of the system and have left thunder out of the forecast
for now. KLBF will see vcts through at least 2z. Line is kind of
sporadic and have just carried vcts. Southerly winds to the east
of the line and will become light and variable once the
thunderstorms get to the east of the station. Some stratus
expected around sunrise with MVFR cigs.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
UPDATE...Power
SHORT TERM...CDC
LONG TERM...Taylor
AVIATION...Power
Area Forecast Discussion...UPDATED
National Weather Service Spokane WA
854 PM PDT Sat Aug 12 2017
.SYNOPSIS...
A cold front will move across the region overnight through early
Sunday morning. The system will come with a risk of showers and
breezy conditions as well as afternoon thunderstorms across the
north and blowing dust across the Basin. Drier, more seasonal
weather is expected for the new work week, before temperatures
start to warm slightly by the end of the week.
&&
.DISCUSSION...
Update this evening to expire/cancel the red flag warnings. The
shortwave moving up the Cascades has moved north into Canada. The
shortwave moving across the central ID panhandle has produced more
exciting results across Idaho county than further north in our
forecast area. We are still getting some light reflectivity across
the Camas Prairie north into Shoshone county which is likely
producing some light rain. The HRRR has been consistent in showing
the rain moving north into Bonner and Boundary counties over the
next few hours, and we may see an isolated thunderstorm out of
that, but not the scattered coverage we were previously thinking.
The cold front is moving onto the west coast. It will move over
the Cascades around midnight and sweep across eastern WA and north
ID through the early morning hours Sunday. Brief light rain is
expected with this front. Gusty winds will accompany the front and
continue through the afternoon hours as well. /Nisbet
&&
.AVIATION...
00Z TAFS: The shortwave is moving north across the Cascades this
afternoon. Convection is firing off across NE Oregon and into SE
WA. This may impact KLWS and KPUW through 03Z with thunder...and
possible vcsh thu 06Z for KLWS. Some of the hi-res models show
convection continuing through the night across NE WA and N ID from
09-13Z, but not impact airports. There will be a gradual
improvement to surface vis due to wind speeds, direction and light
rain. A cold front will arrive overnight...up to the Cascades ard
08Z and then quickly through the region by 18Z. The front will produce
light rain and clear up much of the smoke for Sunday. Breezy winds
will accompany the front with winds continuing through the aftn
for many locations.
&&
.PRELIMINARY POINT TEMPS/POPS...
Spokane 62 77 55 77 56 78 / 10 60 10 10 0 0
Coeur d`Alene 61 75 52 77 51 78 / 20 50 10 10 10 0
Pullman 59 75 49 76 49 77 / 20 40 10 10 0 0
Lewiston 66 83 59 83 59 85 / 20 40 10 10 0 0
Colville 62 78 50 81 50 80 / 10 60 20 20 10 10
Sandpoint 60 75 46 77 45 79 / 20 40 20 20 10 10
Kellogg 59 73 49 74 50 75 / 50 50 20 10 10 0
Moses Lake 64 83 50 82 52 83 / 10 30 0 0 0 0
Wenatchee 65 81 58 82 60 84 / 30 30 10 0 0 0
Omak 64 84 55 83 55 85 / 30 20 10 10 10 0
&&
.OTX WATCHES/WARNINGS/ADVISORIES...
ID...None.
WA...None.
&&
$$
Area Forecast Discussion
National Weather Service Pueblo CO
751 PM MDT Sat Aug 12 2017
.UPDATE...
Issued at 748 PM MDT Sat Aug 12 2017
Updated the POPs for tonight based on current pcpn trends seen on
radar and based on HRRR forecast for later tonight.
&&
.SHORT TERM...(This evening through Sunday)
Issued at 343 PM MDT Sat Aug 12 2017
...Severe thunderstorm chances increase into Sunday for the plains...
Northwest flow will remain over the area with the next upper level
shortwave evident in UT/western Co moving across during the evening
and overnight hours. This in combination with afternoon heating
will trigger thunderstorms across the mountains, some of which will
drift off into the plains during the evening. Of greater note is
potential for one or two strong to severe thunderstorms across
northern portions of the southeast plains this evening along a sfc
trof/outflow boundary. This looks to be a conditional threat however
as model soundings show a cap in place across the plains
today...though this appears to erode close to the mountains and
weaken into the evening north of highway 50. HRRR has been
persistent with this solution which lends credence to keeping some
pops in through the overnight hours across the plains. This area is
under a marginal risk for severe weather and given CAPE values of
1500+ J/kg and 0-6km shears of 40 kts, can`t rule out an isolated
severe storm basically north of highway 50 through this evening.
Otherwise, activity should generally wind down later tonight.
Sunday looks like another active day with higher CAPE and shear
across the plains as upper flow aloft increases. Once again,
thunderstorms will develop over the higher terrain during the
afternoon, however focus will also occur along the surface trof axis
across the plains. With less of a cap and the potential for 2000-
3000 J/kg of CAPE, this day will have the greater potential of
severe thunderstorms. particularly east of a line from La Junta to
Kim. Very large hail, damaging winds and an isolated tornado will be
possible into Sunday evening. Even though dew points will remain
slightly lower across the mountains, there will still be sufficient
moisture for locally heavy rainfall and the potential for flash
flooding on area burn scars should these areas be impacted by a
stronger storm. -KT
.LONG TERM...(Sunday night through Saturday)
Issued at 343 PM MDT Sat Aug 12 2017
Not many many meteorological adjustments required from previous
meteorological reasoning during the longer with issues continuing
to include pops, temperatures, heavy rain/localized flash flood
potential as well as intense storm potential at times
Latest longer term forecast model soundings, computer simulations
and PV analysis indicate that a relatively moist airmass to
continue over the forecast district into Monday, with some drying
then indicated Tuesday before increasing atmospheric moisture
returns from late week into next weekend.
Still anticipate that isolated to scattered shower and thunderstorm
activity will be noted each day with precipitation generally
favoring higher terrain locations during the longer term.
Again, some of the stronger storms will be capable of generating
heavy rain and localized flash flooding concerns and may also be
intense at times. As always, WFO Pueblo will issue hydro/severe
weather products as needed.
Projected maximum and minimum temperatures during the longer term
should hover near mid-August climatological averages in combination
with basically low-grade gradient winds and minimal fire weather
concerns.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 343 PM MDT Sat Aug 12 2017
VFR conditions expected at the TAF sites this afternoon and evening
with brief MVFR cigs/vis possible with isolated thunderstorms
which could impact the terminals during the late afternoon and
evening. All three TAF sites will carry VCTS for now, though KCOS
will see the best chance of thunderstorms through this evening.
IFR stratus is likely to develop across the plains again
tonight...but majority of forecast model simulations keep it just
east of KCOS tonight. This will be a tough call and will have to
watch how this evolves over the next several runs. For now will
carry a BKN010 layer in KPUB through early Sunday morning. Sunday
will carry the risk for stronger storms across the plains,
particularly along and east of the I-25 corridor. -KT
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...28
Area Forecast Discussion
National Weather Service Springfield MO
703 PM CDT Sat Aug 12 2017
.SHORT TERM...(This evening through Sunday)
Issued at 307 PM CDT Sat Aug 12 2017
The batch of showers over the extreme southwest portion of
Missouri and southeast Kansas this afternoon is rather weak and
is struggling to overcome drier low level airmass advecting in
from surface high over the upper Midwest. Stronger storms remain
well to the southwest over the Red River Valley where better
moisture and low level forcing reside along the stalled front.
Further to the northwest...thunderstorms were firing up over the
central High Plains in western and central Nebraska...ahead of
an upper level disturbance and subtle surface trough. The latest
HRRR is not showing much of that activity making it this far to
the southeast tonight, but does keep some weak convection
associated with the northern edge of the eastern Oklahoma
shortwave over southern MO. So for now will continue trend of
gradual eastward spread of showers and storms, but if the trend
continues...central and west central MO will likely remain dry
through tonight.
On Sunday...the NAM and ECMWF show another area of precipitation
developing along the MO/AR border with the approach of another
upper level disturbance moving across the southern Plains.
.LONG TERM...(Sunday Night through Saturday)
Issued at 307 PM CDT Sat Aug 12 2017
The upcoming week still looks warmer and wetter as the upper
level flow shifts from northwest to southwest with a large upper
trough moving into the western CONUS. This will lead to lee side
cyclogenesis and increasing southerly low level flow...along with
several disturbances moving over the region.
We will need to watch for the potential for stronger storms on
Tuesday and Wednesday as moisture, instability and vertical wind
shear increase across the region. A front will set up over
northwest Missouri and central Kansas by midweek, but will likely
not have much of a southern push to bring it this far south.
&&
.AVIATION...(For the 00Z TAFS through 00Z Sunday evening)
Issued at 648 PM CDT Sat Aug 12 2017
KSGF/KJLN/KBBG tafs: An upper level disturbance that extends from
southeast KS into OK will move east into AR for this period. Dry
air will be in place with sfc high pressure extending from IA
south into KS/MO which will limit overall rain potential. Very
light rain will be possible with the best chances along the MO/AR
border. VFR ceilings are expected, but may see some mvfr if
enough moisture can saturate the lower levels. Rain (where it
occurs) overall does not look to have too much affect on
visibility unless an isolated heavier shower occurs.
&&
.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&
$$
SHORT TERM...Terry
LONG TERM...Terry
AVIATION...DSA
Area Forecast Discussion
National Weather Service San Diego CA
108 PM PDT Sat Aug 12 2017
.SYNOPSIS...
A developing low pressure trough near the West Coast early next week
will bring a dry and stable west flow aloft, with gusty westerly
winds across the mountains and deserts. The increasing onshore flow
will build the marine layer, for cooler days as low clouds spread
well inland each morning. High pressure returns for the latter half
of the week, bringing warmer, but continued dry weather. Daytime
temperatures will be below average early this coming week, followed
by a return to average Summer conditions for the remainder of the
week.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
At midday, marine stratus was holding along the beaches of Orange
and northern San Diego County. Just inland it was clear up to the
mountains where a few cu were popping over the highest terrain in
the heat of the afternoon. The sfc pressure gradients was trending
weakly onshore but winds were light with only a few sites reporting
gusts over 20 MPH.
Based on the sfc observations and satellite data, a significant
amount of moisture remains over the mountains of San Diego County
and the lower deserts. The latest HRRR also has generated convection
in the San Diego County Mtns/deserts later today. With that in mind,
slight chance POPS will remain in the forecast through today. For
the remainder of the CWA it will be dry with marine layer clouds
reforming rapidly inland again tonight.
The last vestiges of monsoonal moisture will be shunted east of the
area through Sunday as westerly flow aloft increases in association
with a digging longwave trough over the West. The trough will reach
peak amplification over SoCal on Tue before retreating to the NE
through early Thu. High pressure will then fill the void aloft,
resulting in warming through Fri. A dry W-SW flow will prevail aloft
through this period, limiting any chance for a resurgence of the
monsoon over SoCal. Meanwhile, onshore flow at the sfc will maintain
the marine layer with periods of night/morning low clouds/fog over
coastal and western valley areas. Temperatures will be below average
to begin the new week, then trend back to around average into the
weekend.
Looking ahead to next weekend and beyond...The 12Z ECMWF/GFS/CMC
operational solutions have a return of weak troughing along the West
Coast. This favors near, to slightly below average daytime temps,
and keeps any chance for a sustained monsoonal push remote. All
things considered, this has been a rather nice stretch of weather
for mid August, and it looks like it will continue.
&&
.AVIATION...
122006Z...Coast/Valleys...Through 13/0300 UTC, P6SM vis and SKC,
except BKN clouds 1000-1800 ft msl lingering within 3 sm of portions
of the coast. 13/0300-1400 UTC, stratus re-developing and moving
inland 15-25 sm, with bases around 800-1300 ft msl, tops around 1400-
1800 ft msl, and areas of vis AOB 5 sm. Forecast marine layer
inversion strength of around 8 deg C at 13/1200 UTC.
Mountains/Deserts...SCT-BKN CU/TCU and possibly some isol SHRA/TSRA
over the San Diego/Riverside county mountains and San Diego county
deserts during the through 13/0200 UTC, with bases around 8000 ft
msl and CB tops to 30000-35000 ft msl. Otherwise, P6SM vis and
mostly SKC through Sunday morning.
&&
.MARINE...
No hazardous marine weather expected through Thursday.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...JAD
AVIATION/MARINE...Harrison
Area Forecast Discussion
National Weather Service Topeka KS
603 PM CDT Sat Aug 12 2017
...AVIATION UPDATE...
.SHORT TERM...(This evening through Sunday)
Issued at 302 PM CDT Sat Aug 12 2017
Tonight and Sunday
Two separate disturbances are impacting the region this afternoon.
The first set of southern stream impulses are entering the Texas and
Oklahoma panhandle region with widespread showers and thunderstorms,
stretching as far north as southern KS. Moisture transport in the
low levels is pretty limited given the high pressure in control over
northeast KS, so have removed pops for the afternoon in our
southern areas.
The second impulse currently observed over northeast Montana will
gradually shift southeast tonight and Sunday. A sfc front over the
Dakotas will serve as a focal point for a cluster of thunderstorms
to form across Nebraska during the evening. A veering, southerly low
level jet feeds ample moisture into the system, with most of the
cams shunting the accumulating precipitation eastward towards Iowa
by Sunday morning. Latest runs of the HRRR and the RAP are further
west with the convection developing, and therefore track the cluster
towards north central Kansas after 06Z. However, the ample dry air
in place and weak mid level lapse rates support the models with the
cluster dissipating as it reaches the CWA. Have kept low end slight
chances across far north central areas. Residual high and mid
clouds are expected to spread into the area by the morning. Also
removed pops for Sunday afternoon as all cams signal moisture
availability is limited by the southern stream wave and mcs
rolling through Texas. Similar to today, a mix of diurnal cumulus
and high clouds combine with highs in the lower 80s.
.LONG TERM...(Sunday night through Saturday)
Issued at 302 PM CDT Sat Aug 12 2017
The extended will feature a longwave trough across the
intermountain West which will begin to send out shortwaves into
the Plains by Tues. SW flow aloft atop a broad area of southerly
moist low level flow will set the stage for bouts of convection
across the Plains Tues and beyond. ECMWF and GFS both indicate a
similar pattern with the usual differences in timing of individual
waves. Bottom line is that it looks to be another active and
potentially wet week for parts of the region until the trough axis
passes (if it does) sometime late week into the weekend. Daytime
temps should remain near or just below avg with highs in the 85 to
90 range.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday)
Issued at 603 PM CDT Sat Aug 12 2017
With surface obs and model progs showing a stable airmass over the
terminals through Sunday, VFR conditions should prevail. There is
a low probability for some ground fog in the morning, so will keep
an eye on conditions to see if chances change.
&&
.TOP WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Prieto
LONG TERM...Omitt
AVIATION...Wolters