Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/20/16
Area Forecast Discussion
National Weather Service Bismarck ND
946 PM CDT Mon Sep 19 2016
.UPDATE...
Issued at 938 PM CDT Mon Sep 19 2016
The 22-01 UTC HRRR and ESRL HRRR, and the 18 UTC NAM NEST
continue to depict elevated convective development generally
along and south of US Highway 2 late tonight into Tuesday morning.
This is in association with a weak impulse aloft and low level
warm air advection via a strengthening low level jet east of a
surface low across western South Dakota and Nebraska. Given steep
lapse rates aloft, thunderstorms are possible. The aforementioned
HRRRs have hinted at possibly organized convection in their
updraft helicity fields given the very high deep layer shear with
the jet aloft.
UPDATE Issued at 631 PM CDT Mon Sep 19 2016
The forecast for the remainder of the night remains on track and
was blended to observed trends through 23 UTC. A similar overnight
is expected tonight as was last night with a chance for showers
across the south with a weak impulse embedded in the fast flow
aloft. Given steep mid level lapse rates, did add a slight chance
mention for thunderstorms. Severe weather is not expected.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 224 PM CDT Mon Sep 19 2016
Forecast concern through the short term will be chance for
showers across the south associated with a weak shortwave trough.
In the wake of the low that moved across the northern plains on
Sunday, high pressure was the dominant feature today bringing
mostly sunny skies. As the pressure gradient lessens the winds
across the north have also diminished so no wind advisory was
considered for this afternoon.
Relative humidity this afternoon has fallen to around 20 percent
across the southwest but winds not expected much above 15 mph with
some gusts in the lower 20s.
Tonight, a weak shortwave with move across the southern portion of
the state bringing a chance showers to the southern third of the
state. considered adding some isolated thunderstorms but cape is
pretty meager so kept only showers.
On Tuesday the will return to partly to mostly sunny skies as the
shortwave trough moves east. Highs tuesday again in the 70s.
.LONG TERM...(Tuesday night through Monday)
Issued at 224 PM CDT Mon Sep 19 2016
The extended period will be feature a significant upper level low
forecast to move from the Great Basin northeast into the northern
plains by Saturday. This will bring a good chance for showers to
the western portion of the forecast area.
Tuesday night and Wednesday, as the upper flow begins to back to
the southwest, will bring the opportunity for some shortwave
energy to support scattered showers. Once again the instability
remains slight so have limited the chance for thunderstorms to
slight and that across the south.
Thursday and Friday will see increasing chances for showers
across the west as the upper low approaches. The GEFS
climatological QPF supports the best rainfall across Montana with
some in western North Dakota with this weather pattern. This
would tend to support the GFS solution over the ECMWF for best
chances for precipitation across western North Dakota Thursday
night though Saturday. Again the instability appears to slim for
Thursday and wait until Friday and saturday to add chance for
thunderstorms.
As the upper low lifts out on Sunday the precipitation will trail
off.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 938 PM CDT Mon Sep 19 2016
VFR conditions are expected across western and central North
Dakota for the 00 UTC TAF cycle. Scattered showers and isolated
thunderstorms are possible across southern North Dakota tonight
into Tuesday morning, possibly impacting KDIK/KBIS/KJMS.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AYD
SHORT TERM...WAA
LONG TERM...WAA
AVIATION...AYD
Area Forecast Discussion
National Weather Service State College PA
1058 PM EDT MON SEP 19 2016
.SYNOPSIS...
Drier air will overspread the remainder of the region tonight.
Skies will clear and winds will be light...promoting fog formation
in many areas. A building ridge bring above normal temperatures
into our region for the remainder of the work week. The larger
scale south- southeast flow favors low moisture and thus little
chance of significant rainfall. But it will be unseasonably warm.
A back door cold front the west should provide some more
seasonable temperatures for part of the weekend.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Clouds will be slow to decrease over the east for much of the
night as high clouds continue to stream NNE from the mid Atlantic
region. The western half of PA is clear to partly cloudy...and
will remain so overnight.
Very light gradient and very light winds combined with recent
rainfall favor fog in central and southern areas after midnight.
Patchy dense fog is possible early Tue morning. North and west
areas will have less fog due to the drying out that occurred today
and southern and southeastern areas could have areas of diminished
visibility. We were optimistic in clearing things out by mid-
morning Tuesday.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
After AM fog burns off it should be a warm for one of the last
days of summer, which officially ends Thursday! But don`t tell the
atmosphere as this summer has other plans.
Should be a nice summer day Tuesday many areas will be in the 80s
a good 6-10F above normal.
The overnight will be relatively pleasant due to lower humidity
and the longer nights now almost 12 hours long! But it is now fog
season so lots of patchy fog is expected overnight.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
By Wed, surface high pressure area will be centered over PA.
Patchy valley fog will give way to a mostly sunny and very warm
day, with highs peaking in the upper 70s to mid 80s as 5H heights
exceed 588dm.
As high moves off to the east, a weak frontal boundary will be
pushed across the Great Lakes late week and through PA on Sat as
sprawling high pressure area builds from central Canada into the
northeastern U.S. in response to a longwave trough over the
Rockies. Ahead of the boundary Thu and Fri, well-above normal
temperatures will continue even as heights very slowly fall and
clouds become more prevalent over the NW.
By Saturday, a back-door "cool" front slides through, bringing
just a chance for showers and a push of somewhat cooler air that
will nudge temps back down toward seasonal norms. Dewpoints will
also drop off significantly as well, leading to a couple cooler
nights.
Upper flow over the western U.S. shifts to ridging early next
week, with northwest flow aloft over PA. GFS/ECMWF bring a
shortwave over PA Mon/Mon night, with the EC being notably more
aggressive with strength. No matter the strength, the system
should be moisture-starved and could only muster chance pops
across NW half for now. But it should be enough to keep temps near
normal much of next week.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
Clear skies, a calm wind and wet ground from recent rain is
causing fog to form across the western half of the state late this
evening. 11-3.9u satellite imagery starting to show the patchy
fog over the northwest Mtns. KBFD just fell to 1/2sm at 0240Z, but
RAP showing drier air mass working in overnight, so forecast not
straight forward at KBFD. Expect vis to bounce in and out of IFR
for several hours before a higher certainty of dense fog arnd
dawn. Based on 02Z dwpt depressions and latest HREF output, expect fairly
widespread LIFR/IFR conditions btwn 08Z-12Z, with the likely
exception of KJST, whose ridgetop location is unfavorable for
radiation fog.
SREF and mos guidance suggest VFR conditions should return over
most of central Pa by 15Z Tuesday, give or take an hour or so.
Sunny skies and a light wind indicated for the balance of the day.
Outlook...
Wed-Sat...Patchy AM valley fog possible.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Grumm
NEAR TERM...DeVoir
SHORT TERM...Grumm/Lambert
LONG TERM...RXR
AVIATION...Fitzgerald
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
1135 PM EDT MON SEP 19 2016
.AVIATION...
The dynamics overall are very weak along a cold front slipping into
the region as mean flow is parallel to the boundary. No
precipitation is expected overnight. High cloud convective debris is
blanketing the region at the moment and is expected to hang around
for the start of the period eventually transitioning to SKC by
Tuesday morning. A geopotential height rise maximum is expected
strengthen substantially over southeastern Michigan tomorrow in
response to strong upper level jet dynamics spreading over Canada.
This will cause subsidence to overwhelm the the column and and lead
to rapid development of a surface anticyclone. Very quiet weather is
expected for Tuesday.
//DTW Threshold Probabilities...
* None
&&
.PREV DISCUSSION...
Issued at 326 PM EDT Mon SEP 19 2016
DISCUSSION...
A warm afternoon as temperatures have climbed into the lower 80s,
but dew pts are not terribly high, predominately in the upper 50s.
Mainly dry cold front to slowly sink south through southeast
Michigan Tonight/Tomorrow morning as upper wave lifts northeast into
Ontario, with zero height falls extending south of over southern
Lower Michigan. Narrowing/pinched off 850-700 mb Theta-e ridge axis
extending from the midwest, with showalter index telling the tale,
going from slightly negative this afternoon over northern lower
Michigan, to decidedly positive as the front sinks south overnight.
The normally aggressive HRRR (17z) with respect to radar
reflectivity also shows line of showers/thunderstorms dissipating as
it enters our CWA. Will shave off about 5 percent inherited pops
tonight. Best chance of activity will be early this evening across
Tri-Cities region and with 30 knots of flow at 850 mb, stronger wind
gusts of 40 to 50 mph are not out of the question if activity
arrives soon enough before strong surface based inversion begins to
develop.
Upper level westerly confluent flow Tuesday afternoon/Tuesday night
with surface high in place. 925 mb temps climbing back to 20 C
supports highs around 80 degrees. Question on Wednesday is will the
the retreating high/dry-stable airmass hold on enough during the
day on Wednesday to maintain dry forecast as warm front lifts into
Western Great Lakes. High degree of instability/moisture pooling
over the Midwest could support an organized MCS which could then
potentially persist enough to allow for showers to sneak into the
cwa late as moisture transport ramps up across the State. PW
values push above 1.5 inches across northern lower Michigan. Much
better chance of showers and thunderstorms Wednesday Night with
the moisture axis better established, but best level fgen forcing
still looks to be mostly over northern lower Michigan.
Warm front will extend into the northern Great Lakes region from low
pressure developing on the Plains Thursday. Model consensus supports
the active portion of the front mainly north of Southeast Michigan
with most of our area in the warm sector Thursday. This front is
expected to sag southward Thursday night/Friday, bringing the threat
of precipitation to much of our area. Strong high pressure over
central Ontario will usher in a cooler/drier airmass by the weekend
with northeasterly flow setting up locally.
MARINE...
Southwesterly winds will increase through the evening hours as the
pressure gradient tightens in between an exiting high pressure
system and approaching trough. The cold front will weaken as it
tracks southeast across the eastern lakes tonight. Wind gusts should
peak around 20 knots ahead of the front before turning northwesterly
overnight. Gusts will continue to peak near 20 knots as cooler, less
stable air works into the region. Showers and thunderstorms will
accompany the front over northern and central Lake Huron with
coverage decreasing southward. High pressure will bring a weaker
gradient and more stability back to the region Tuesday night.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
AVIATION.....CB
DISCUSSION...SF/DT
MARINE.......DRK
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Peachtree City GA
753 PM EDT MON SEP 19 2016
.UPDATE...
WV loop showing much drier airmass across the state this
evening...with one lone TS moving across Madison county.
Not much change needed to the forecast thru the short term.
Generally clear skies overnight...with low clouds possible across
eastern and southern counties towards sunrise as winds shift to
the northeast. Although moisture will be gradually increasing
from the east...most areas will stay dry Tuesday. A cutoff low
progged to be centered across eastern Ga/SC may squeeze out a few
showers across northern and eastern counties Tuesday afternoon as
it slowly meanders around the area.
Low temps tonight mid to upper 60s and high temps Tues upper 80s.
Kovacik
&&
.PREV DISCUSSION... /Issued 331 PM EDT MON SEP 19 2016/
SHORT TERM /Tonight through Tuesday Night/...
The latest regional surface analysis shows low pressure continues
off the Carolinas coast...spreading moisture back to the west into
the western Carolinas and eastern GA. RAP upper air analysis shows
upper low just to the west of the surface feature but continues to
sink further south and east with time.
With this setup...most of the activity has remained to the east
and south of the local area and best chances for the remainder of
the afternoon and into the evening looks to be over
telfair...Wheeler...Montgomery and Toombs. There has been a
surprising amount of low topped shra activity over portions of AL
and have included 20 pops for all locations because of this.
Upper low continues to shift southeast through Tue but moisture
actually increases over the eastern sections of the area as
circulation around both this and surface feature brings enhanced
moisture back toward the local area. Forcing and instability look
limited with this and low end chance pops look to suffice through
the remainder of the short term period.
Deese
LONG TERM /Wednesday through Monday/...
No major changes made to the extended forecast. Long range models
show fairly good agreement through the long term... with each
model beginning the period with a cut off upper low spinning over
southeast Georgia and South Carolina where it meanders through
Thursday or Friday before gradually shearing eastward over the
weekend. This feature will likely keep some form of a weak surface
low or trough along the coasts of Georgia and Carolinas through
the work week. The resulting easterly wind flow will try to spread
Atlantic moisture back over at least the eastern portions of the
forecast area... and this will warrant holding onto a slight to
low chance of showers and thunderstorms over at least the eastern
zones through much of the period. The good news is instabilities
seem to remain in check as expected cool east winds coupled with
increasing clouds hold afternoon cape values in the 800-1200 J/KG
range Wednesday through Friday. Cape values increase a bit over
the weekend as the upper low shears out... which likely increases
afternoon sunshine and daytime temperatures. However... high
pressure building in from the west along with a fairly dry
northerly wind flow will continue to help hold rain chances down
in the 20-30 percent range at best over the weekend. Otherwise...
expecting highs to hold mainly in the 80s through the work week...
with some lower 90s likely by the weekend with increasing
sunshine. Lows should run mostly in the 60s.
01
&&
.AVIATION...
00Z Update...
Quiet conditions at most TAF sites at 00z. A lone TS is moving in
the vicinity of AHN with a TEMPO covering this. Wind shift to the
northeast will occur overnight tonight with VFR conditions
prevailing. Towards sunrise Tues...MVFR ceilings possible across
AHN and MCN...lifting to VFR by 14z. Generally quiet conditions
expected Tuesday with SCT cu developing late morning/early
afternoon.
//ATL Confidence...00Z Update...
Medium on MVFR ceilings...High on all else.
Kovacik
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 68 88 69 84 / 30 20 20 30
Atlanta 69 88 71 85 / 20 10 10 20
Blairsville 60 85 62 83 / 20 20 10 10
Cartersville 65 89 66 87 / 20 10 10 10
Columbus 71 92 71 89 / 20 10 10 20
Gainesville 68 87 69 84 / 20 20 20 20
Macon 69 90 69 87 / 20 10 10 30
Rome 65 89 66 88 / 20 5 5 10
Peachtree City 67 89 67 86 / 20 10 10 20
Vidalia 72 88 71 86 / 30 20 20 40
&&
.FFC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Kovacik
LONG TERM....41
AVIATION...Kovacik
Area Forecast Discussion
National Weather Service Wilmington NC
1107 PM EDT Mon Sep 19 2016
.SYNOPSIS...
The remnants of Julia will remain across eastern North Carolina
through much of the week and this will keep the weather rather
unsettled. High pressure will build into the area by the weekend
finally bringing drier conditions. A cold front will move across
the area during Sunday bringing the first hint of Autumn early
next week.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of 800 PM Monday...The weak circulation that was near
Cape Lookout and moving NE. the significant rainfall associated
with the remnant low was now offshore and well to out NE. An area
of weakening convection in association with and upstream upper
trough was creeping SSE, and will likely dissipate to the west of
our westernmost zones through 1 am. The upper trough is expected
to close off as it moves across the eastern Carolinas overnight
and Tue.
The HRRR has been doing an outstanding job modeling these two
systems this eve. Thus, we have relied heavily on its forecast.
There may be some showers that are able to wrap in and around the
remnant low to our NE toward morning. Have dropped pops to slight
chance or just below threshold overnight. Given the widespread
nature of the rainfall today with many locations receiving a good
soaking, added some fog to portions of the area. The fog could
become more widespread if winds do not tick up on the backside of
the remnant low. Model soundings are supportive of low stratus
enveloping the area as cooler NW winds drop temps to or near
dewpoints values. Low temps are expected to be around 70 degrees.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...A general troughiness along the coast
anchored by the remants of Julia will characterize the short term,
with ample moisture of tropical origin continuing the threat for
unsettled weather through the period. As moisture will not be as
deep as it was on Monday, do not see the threat for localized
flooding to be as high. However, it cannot be ruled out,
especially for slow moving and training storms. Ample cloud cover
will keep highs capped in the lower to mid 80s for both days
although elevated dewpoints will give us higher feels-like
temperatures. Lows will be right around 70 for both nights.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 300 PM Monday...Unsettled weather is expected through much
of the long term period as the remnants of Julia slowly meander
near southeast NC. In addition, a weak upper low will linger with
high precipitable water values. Eventually, during the weekend,
the weak upper low dissipates with drier air moving into the
column while a cold front pushes into the area during Sunday. High
pressure will build in from the north during Monday. Above normal
highs/lows will continue Thursday through Saturday, then below
normal temperatures are possible by Monday in the post-frontal
air-mass.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
As of 00Z...What is left of the tropical system Julia is pulling
away to the north, taking most of the rain with it. Look for
northerly winds tonight with IFR stratus once again becoming
predominate over the region, due to the northerly flow and
abundant moisture at the surface, these IFR conditions are
expected to prevail for much of the day on Tuesday with continued
northerly flow.
EXTENDED OUTLOOK...Mainly afternoon convection along the coast
through Friday with morning stratus/fog possible each day.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 1100 PM Monday...The remnants of Julia were evident near
Cape Lookout and moving slowly NE. In its wake, the wind
direction will continue from the NW. Wind speeds will be up to 10
to 15 kt. Seas will be 2 to 4 ft. Showers and some thunderstorms
will be most numerous offshore overnight.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 300 PM Monday...The remants of Julia will persist in the
vicinity with a region of general troughiness. Although weather will
remain unsettled in the form of showers and thunderstorms, winds and
seas will remain fairly benign through the short term. We can expect
seas of around 2 or 3 ft, with winds of around 10 kts each day.
LONG TERM /THURSDAY THROUGH SATURDAY/...
As of 300 PM Monday...A weak pressure gradient will exist across
the waters Thursday through early Saturday with speeds at or about
10 knots or less and seas less than 3 feet. North to northeast
flow increases behind the cold front Sunday with seas increasing
to 3-4 feet. The northeast flow weakens quickly during Monday as
high pressure builds in from the north.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
NEAR TERM...RJD
SHORT TERM...REK
LONG TERM...MBB
AVIATION...DL
Area Forecast Discussion
National Weather Service Lincoln IL
902 PM CDT MON SEP 19 2016
.UPDATE...
Issued at 900 PM CDT Mon Sep 19 2016
Some dense cirrus clouds are flowing into our western counties as
a supercell moves south through northern Missouri. The line of
storms in eastern Iowa are dissipating as they approach NW
Illinois. We lowered PoPs to just slight chance NW of Peoria, and
even that is looking questionable with the amount of dry and
stable low level air across central IL. Even if rain does not
occur, there should be a band of mid clouds move into the NW half
of our forecast area overnight, before dissipating toward sunrise.
That may help keep low temps slightly warmer in that area. Our
forecast already has our warmest lows in the western counties,
with mid 60s. Eastern areas should be able to drop into the low
60s or possibly upper 50s.
Updates this evening were done to the weather and sky grids,
otherwise the forecast looks on track.
&&
.SHORT TERM...(This evening through Tuesday)
ISSUED AT 254 PM CDT Mon Sep 19 2016
1018 mb surface high pressure over the Ohio and mid MS river
valleys and upper level ridging building into central/southern IL
was providing a sunny and warm afternoon with temps mostly in the
mid 80s. Dewpoints had mixed down into the mid 50s to lower 60s with
SSW winds 5-15 mph and few gusts of 15 to 20 mph.
The latest Hi-resolution forecast models remain in very good
agreement with a cold front over central parts of WI/IA weakening as
it pushes toward the IL river valley late tonight. A narrow band of
convection was starting to develop along this front where unstable
airmass present with CAPES of 2-3k J/kg. Models show isolated
convection moving into areas along and nw of the IL river late this
evening and early overnight before dissipating before it reaches I-
55 as instability that peaks from 800-1600 J/kg nw of IL river late
this afternoon and early evening, wanes and front moves into a flat
upper level ridge over central IL with 500 mb heights getting at or
above 590 dm. May see some patchy fog develop during overnight over
southeast IL south of I-70 and lift by mid Tue morning with light
winds, but fog coverage and denseness should be less than the past
couple of nights. Partly to mostly sunny skies and warm summerlike
conditions should prevail on Tuesday with strong upper level ridge
holding over central/southern IL.
Lows tonight will be in the low to mid 60s with coolest readings
near the IN border where lows around 60F. Highs Tuesday back in the
mid to upper 80s with dewpoints in the 60s. These readings are about
10 degree warmer than normal for mid September.
.LONG TERM...(Tuesday night through Monday)
ISSUED AT 254 PM CDT Mon Sep 19 2016
Surface high pressure will continue to slide into the northeastern
US and bring the return of south to southwesterly flow into the
middle part of the US and the central Mississippi valley. This will
also allow a mid level ridge to build into the southern and
southeastern parts of the US for the week and into the weekend. This
pattern will keep the CWA dry and allow 850 temperatures to warm
into +18C to +20C range, resulting in afternoon highs reaching into
the middle to upper 80s for the week and into the weekend. Any wave
or weak weather system will move across the northern US, keeping any
precip north of the CWA through the period. Extended models have
slowed with the next possible weather system this weekend, and now
looks like chance of precip will move into the western part of the
CWA beginning Sunday and then spread across the north and central
part of the CWA Sunday night. Though there is timing differences on
the onset of precip, both models shear the mid-level system into the
northern part of the midwest. So precip should be short-lived,
resulting in a dry forecast for Monday. However, temps should cool
for Monday due to cloud cover and the passage of a weak front.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 637 PM CDT Mon Sep 19 2016
A cold front will push into NW Illinois later this evening,
dissipating as it reaches the Illinois river and eventually I-55.
SPC Mesoanalysis page shows a much more stable airmass in our
counties than areas upstream in Iowa where a tornado watch is in
effect until 10 pm. We do not expect storms to affect Peoria, nor
any of our terminal sites overnight. The latest HRRR has a steady
decline in storms as the front reaches near the IL river. The RAP
shows some showers reaching PIA, but will leave all TAFs dry this
evening for now.
Forecast soundings show the potential for some MVFR ceilings for
PIA and BMI late tonight as the front stalls out and dissipates
across our northern counties. Residual boundary layer moisture
could be enough for patch fog in low lying areas. MVFR fog may
affect PIA later tonight, with other fog potential mainly south of
I-70.
Winds will start out from the south-southwest at 5-7kt, then
become light and variable overnight. Wind directions will shift to
the southeast tomorrow morning, then trend easterly by late in the
TAF period. Wind speeds tomorrow should generally remain below
10kt.
&&
.ILX Watches/Warnings/Advisories...
NONE.
&&
$$
UPDATE...Shimon
SHORT TERM...07
LONG TERM...Auten
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
830 PM CDT MON SEP 19 2016
.UPDATE...
822 PM CDT
Quite a fascinating atmospheric display this evening as showers
and storms continue to fire in much of southern Wisconsin, but
with the wall of instability and shear not moving, these storms
quickly weaken as they approach Illinois and the radar returns
fade. It is likely that some of this activity will sneak into
Illinois this evening as a cold front works its way southeastward,
but the increasingly less hospitable environment should continue
to allow for a dissipation of this activity to largely just some
lighter rain showers as some moistening occurs overnight. The
exception may be along the border where some lightning is briefly
possible.
KMD
&&
.SHORT TERM...
226 PM CDT
Through Tuesday...
Main forecast concerns/challenges are with shower thunderstorm
chances and trends late this afternoon through the evening, with
the potential for a strong to severe storm remaining through
early/mid evening around the RFD area.
Showers and thunderstorms are currently developing along surface
trough and front across Wisconsin and far northeast Iowa. This is
occurring as speed max pushes through the upper midwest and while
instability has increased within moisture axis. Still monitoring
potential for current upstream robust thunderstorm development to
shift across the far northwest CWA as this front drops south this
evening, mainly along/northwest of a Dixon to Antioch line.
Several factors supporting rather strong development this
afternoon across the region including steep mid/low level lapse
rates, strong upper level support, and increasing bulk shear
supportive of more organized development. However, at this time,
the higher instability axis is currently situated just to the
north/northwest of the area and significantly decreases the
further into northern Illinois. This is evident in latest RAP
analysis but even more noticeable given the lower dewpoints which
have settled in across the CWA.
For this afternoon, next couple hours, anticipate any shower and
thunderstorm development to stay just outside of the CWA. As we
move into the 22-00z time frame, would anticipate this upstream
development to begin pushing into far northern Illinois as front
and instability axis inch closer with the Rockford area seeing the
highest chances. The potential for strong to severe storms will
occur during this time, with large hail and damaging wind gusts
the main threats. However, as soon as this occurs, instability
will likely quickly lower this evening with the threat of stronger
thunderstorms also lowering. Although precip may continue to drift
further into areas in north central and northeast Illinois this
evening, this precip will likely be decaying with thunder becoming
more limited. By late evening and the overnight hours, any
lingering showers will further diminish as they drift south but
with locations in east central Illinois and northwest Indiana
likely staying on the dry side.
Rodriguez
&&
.LONG TERM...
210 PM CDT
Tuesday night through Monday...
Tuesday night through Thursday:
The medium range will begin with a large mid-lvl ridge centered over
the Southern Plains stretching north through the Ohio Valley, with a
quasi-zonal orientation to the longwave pattern across the northern
latitudes of the CONUS. Surface features should keep anti-cyclonic
flow in place for the Ohio Valley, which places the far Western
Great Lakes region along the fringes of where precip/storms could
clip. Present thinking is that with guidance progging a vort-lobe
over the Central Plains, this feature should slide east/northeast
following the flow of the 500mb ridge top. The best chance for POPs
continues to be more focused north of the forecast area through at
least Thursday; however, it is possible that the boundary could
become oriented further south and increase the chances for precip.
Temps will continue to be mild with highs generally in the low/mid
80s, but with the lack of a moist boundary layer of late, it is
possible that highs could easily bump a degree or two warmer with
the continued southerly flow.
Friday through Sunday: Minimal changes to the extended periods with
continued mild weather. The longwave pattern maintains ridging over
much of the eastern CONUS, as a deep trough digs into the Southwest
CONUS. This could help to further amplify the downstream ridging
over the Great Lakes/Ohio Valley. Guidance does suggest a surface
ridge over the Canadian Prairies late week will try to slide south,
which could help to push the surface boundary south across the
forecast area Saturday, and could bring slightly cooler air to the
forecast area. But this could be short-lived as the mid-lvl trough
from the Southwest CONUS begins to push east of the Rockies and
helps to strengthen the warmer southerly flow through the Great
Lakes/Ohio Valley for the weekend.
Beachler
&&
.AVIATION...
For the 00Z TAFs...
Spc mesoanalysis depicts a "wall" between the unstable airmass in
WI and IL. Radar reflectivity returns show a considerable demise
across our area, and a signficant decline in southwest WI which
has a similar airmass to much of northeast IL and northwest WI.
There is some upstream development that guidance suggests may
survive into northeast IL as some brief lighter rain later this
evening, but should be relatively low impact.
Winds will generally be shifting to NE overnight, but should be
relatively light, coming in this evening as outflow from storms
combines with the southward moving frontal boundary. Timing for
ORD is 3z but could be a bit sooner if it keeps moving. There
could be some fog later tonight away from the metro sites as the
cooler airmass moves in, and guidance is hinting at possibly some
lower ceilings coming in off the lake late tonight into early
Tuesday. Confidence is still low on its occurrence, but if it does
it would be MVFR and occur in the 11-14z time frame. East winds
increase tomorrow through the day.
KMD
&&
.MARINE...
210 PM CDT
Broad surface ridge will linger across the Great Lakes region
through Tuesday, before shifting southeast and allowing for a
southwest/south flow to develop. The gradient does appear to
tighten across the northern portions of Lake Michigan tuesday
afternoon/evening, but should remain below 25 kt based on current
guidance. A frontal boundary may try to slide south and stall
across the central portions of the lake late Wednesday, producing
northeasterly winds to the north and southerly flow to the south.
Then as a low pressure develops across the Central Plains and
lifts northeast towards Lake Michigan early thursday, this should
lift the frontal boundary back north and allow the entire lake to
see southerly winds thursday afternoon through friday.
Beachler
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...NONE.
&&
$$
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Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
653 PM CDT MON SEP 19 2016
.UPDATE...
Issued at 643 PM CDT Mon Sep 19 2016
Updated the forecast this evening to account for the latest radar
trends. One lone supercell has managed to sustain itself across
southern Iowa. However, mesoanalysis data suggests that the MLCAPE
gradient has only managed to make it as far east as south-central
IA and north-central MO. Latest radar loops show the main storm
complex diving south along this gradient, which will keep the
severe threat west of the LSX CWA. At this point, seems the only
way to get precip in our area is for the storm to weaken and
become more elevated, which would cause it to move more eastward
with the mean deep-layer wind fields. For this reason, will keep
slight chances in northern MO over the next few hours, before
going dry in all areas tonight.
Also upped the fog wording a bit across southeastern MO and
southwestern IL. Very similar setup to last night in this region
with light winds expected and mainly clear skies. Dewpoints did
mix out into the lower 60s today which may help mitigate how dense
it becomes, but think areas of fog will be likely again in this
region overnight.
KD
&&
.SHORT TERM... (Through Late Tuesday Afternoon)
Issued at 315 PM CDT Mon Sep 19 2016
Weak vort max currently moving across Iowa will move slowly east
southeastward into west central Illinois later this evening. This
will cause a cold front currently over central Iowa to move into
northeast Missouri toward midnight. Instability along the front
will be waning with the loss of daytime heating, and convergence will
be relatively weak, so have kept with just a slight chance of
showers and thunderstorms late this evening and overnight across
northeast Missouri and west central Illinois. This goes along well
with latest runs of the HRRR and NSSL WRF which are showing isolated
storms developing over the northern part of the CWA during this same
time period. Still expect tomorrow to be dry as the upper ridge
continues to build over the area.
Do think there will be some additional fog development tonight as
the winds will be light, and all but the northern CWA will see
mainly clear skies. Like the past few nights, worst of the fog
will be near the river valleys.
Coolest temperatures will be over southeast Missouri and south
central Illinois where winds will be the lightest and skies will be
the clearest in the retreating surface ridge axis. Agreeable MOS
lows look reasonable. Went at or above MOS tomorrow with highs
given the expected mostly sunny skies and mixing into the 900-850mb
range.
Britt
.LONG TERM... (Tuesday Night through Next Monday)
Issued at 315 PM CDT Mon Sep 19 2016
(Tuesday Night - Friday Night)
Two features will largely dominate the sensible weather across the
mid-Mississippi Valley heading into early next week: 1) surface
ridge nearly anchored across the northeastern United States
southwestward into the lower Ohio Valley and 2) mid/upper level
ridge overhead. Both of these features will help promote plenty of
clear skies and above normal temperatures. The area will also be by
and large precipitation free as any chance of widespread shower and
thunderstorm activity look very small. Dewpoints will be in the
mid 60s to near 70 degrees each day so it will even feel a bit
hotter than the forecast highs of roughly 85-90 degrees each
afternoon. Warmest days of this forecast period appear to be on
Wednesday and Friday where highs in the upper 80s to near 90 degrees
are expected. Nighttime lows will initially start off fairly
seasonable on Tuesday night and even Wednesday night due to the
clear skies and sfc ridge near the area. Dropped minimum
temperatures a few degrees in the eastern Ozarks each of these
nights from previous forecast. Lows are expected to moderate a
few degrees by Thursday night and Friday night...mainly due to
slightly increased southerly surface flow.
(Saturday - Next Monday)
Backdoor cold front will try and push southwestward into the CWA on
Saturday. Slightly cooler temperatures are likely compared to Friday
due to an increase in cloud cover predominantly. Still lots of
uncertainty heading toward late this weekend and early next week.
Evolution of closed low in the Rockies continues to cause problems
in the medium range. Latest guidance suggests a portion of the
closed low hanging out in the desert southwest with a portion
ejecting out into the northern Plains on Saturday night/Sunday. This
portion should send a cold front down toward our way either on
Sunday or Monday. Continue to lean toward the slower end of the
guidance envelope. Temperatures on Saturday and Sunday continue to
look warmer than 24-48 hours ago with the highest PoPs now on Sunday
night coincident with the expected frontal timing...though would not
be surprised if it is yet delayed another 12 hours.
Gosselin
&&
.AVIATION... (For the 00z TAFs through 00z Tuesday Evening)
Issued at 618 PM CDT Mon Sep 19 2016
Dry and VFR conditions are expected through the period. A cold
front currently across portions of southern IA will make some
southward progress tonight. Although the storms associated with
this front should remain off to the west, some clouds will likely
affect UIN tonight into Tuesday morning. Can`t rule out some MVFR
cigs during this time, but will leave out for now given fairly low
confidence on how far south the front will get. Expect IFR fog
once again at SUS/CPS early Tuesday morning, before all sites go
VFR by late Tuesday morning into the afternoon.
SPECIFICS FOR KSTL:
Expect dry and VFR conditions through the period. Light southwest
winds will persist through the period with few/sct diurnal cu
Tuesday afternoon.
KD
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
1102 PM CDT MON SEP 19 2016
.UPDATE...
Issued at 1102 PM CDT Mon Sep 19 2016
Updated to include 06Z aviation discussion below.
&&
.SHORT TERM...(This evening through Tuesday)
Issued at 330 PM CDT Mon Sep 19 2016
We will spend the short term portion of the forecast on the southern
edge of a 120kt jet streak up along the international border. This
will continue to send mid level impulses our direction. One came
through this morning and is already working through southern
Wisconsin. The next is working across Wyoming and will be working
into western MN late tonight. This will bring another reinforcing
shot of mid level clouds for Tuesday, and like today we will see
some high based showers. The HRRR shows light rain moving into
western MN around 12z, with the NAM/NMM/ARW showing this band
lifting northeast across central MN through the morning on a push of
isentropic forcing on the 305/310k surfaces. We did add some chance
pops from western into central MN Tuesday morning for that. By the
afternoon, 925-850 moisture transport starts to increase in SW MN as
the LLJ begins its strengthen. Though the heavier precip and bulk of
the thunderstorms are expected Tuesday night, the GFS/ECWMF are
kicking off some light QPF on the nose of the LLJ by Tuesday
afternoon. For now, maintained a dry forecast there as moisture
depth looks lacking, with deep moisture arriving for the start of
the long term period.
Across central MN, we have seen dewpoints mix out into the upper
30s/lower 40s this afternoon, and with winds remaining light tonight
with skies being clear, we should see temperatures drop off pretty
quick. Dropped lows in central MN into western WI down into the 40s.
This dry air also looks to keep fog at bay, unless you are by a warm
body of water. For Highs tomorrow, airmass is similar to what we
have today, so it will be another pleasant day with highs in the
70s.
.LONG TERM...(Tuesday night through Monday)
Issued at 330 PM CDT Mon Sep 19 2016
Heavy rainfall and possible flooding remain the primary weather
threats Tuesday night into Thursday. Wednesday and Wednesday
night still look to be the higher risk periods. Coverage area
also looks to be in the vicinity of the warm front/stationary
frontal boundary across southern MN into WI.
Models suggest surface warm front lifting into far southern
Minnesota later Tuesday night decent moisture return with the
25-35kt LLJ. This should be strong enough to generate
thunderstorms into southern MN and high pops were retained. Some
risk of large hail with thunderstorm development Tuesday night with
steep mid level lapse rates and modest instability/shear. Heavy
rainfall is also a threat...but areal coverage may not be that
widespread...affecting mainly south central MN.
Nevertheless...PW`s increase with the warm front so if training of
storms develops...heavy rain will be a threat.
The better chance of more widespread heavy rainfall looks to be
Wednesday into Thursday with PW`s enriched with some tropical
moisture from then Tropical Depression Paine. This increases PW`s
to at least the 90th percentile. So WPC`s outlook of increased
risk of excessive rain looks good during this period. Held off on
watch at the moment to better determine overall coverage area that
will be affected. Still looks like widespread 1 to 3 inches of
rain with locally higher amounts possible...especially if training
along the front develops across southern MN.
The front is still forecast to drop southeast as the upper trough
moves through. THis should leave an overall lull in the rain
threat until mainly Later Friday into Saturday night. A more
amplified pattern is suggested with the models with the next
frontal passage forecast to move through Saturday night into
Sunday night. This system looks progressive...so this should limit
overall heavy rain/flood threat.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1102 PM CDT Mon Sep 19 2016
Not much change from previous forecast, with reasoning still
looking similar. We`ll see some lower clouds work into the area
toward the tail end of the period, with precipitation still mainly
looking to occur after 06Z. However, there is a slight chance that
KAXN and KSTC could see some light precipitation from VFR ceilings
this morning as we see initial mid-level warm advection start to
work into the area. But, with nothing upstream at this point, and
ceilings and visibility looking like they`d stay VFR even if it
does precipitate, did not include any mention at this point.
KMSP...Main uncertainties are will the timing of precipitation
toward the end of the forecast. Did include a TEMPO group with
this issuance, since it appears somewhat likely that we`ll have
things nearby after 06Z, although some of the guidance is keeping
things south of the area through the full forecast period. Where
things wind up will obviously impact ceilings and visibilities,
and it unfortunately could be during the 09-12Z time frame when
arrivals/departures increase.
/OUTLOOK FOR KMSP/
Wednesday...MVFR expected, IFR possible with showers and
thunderstorms. East wind 10 to 20 kt.
Wednesday night...MVFR expected, IFR possible with showers and
thunderstorms. Southeast wind 10 to 15 kt.
Thursday...MVFR expected with a chance of showers and
thunderstorms. Southeast wind 10 to 20 kt.
Thursday night and Friday...MVFR possible. East wind less than 10
kt increasing to 10 to 15 kt Friday.
&&
.MPX Watches/Warnings/Advisories...
WI...None.
MN...None.
&&
$$
UPDATE...
SHORT TERM...MPG
LONG TERM...DWE
AVIATION...
Area Forecast Discussion
National Weather Service Marquette MI
721 PM EDT MON SEP 19 2016
.SHORT TERM...(This evening through Tuesday)
Issued at 401 PM EDT MON SEP 19 2016
WV imagery and RAP analysis indicated a mainly zonal pattern across
the nrn CONUS with a 130-140 knots 250-300 mb jet from the nrn plains
to the Upper MS valley. Upper level div with the left exit of the
jet along with 700-300 qvector conv with a shortwave trough from
nrn Ontario, w of James Bay, to Upper Michigan supported a band of
-shra over ern Upper Michigan. MLCAPE values into the 500-1000 J/Kg
range to support TS remained just to the south and east of the cwa.
Strong subsidence/drying in the wake of the shrtwv has brought
clearing with sunny skies over the west half of Upper Michigan.
Tonight, mostly clear skies and drier air into the area with pwat
values to around 0.40 inch will result in favorable radiational
cooling conditions over inland locations where the winds will become
light. Min temps should drop into the mid 40s. However, a tighter
pressure gradient and more winds/mixing will keep temps in the upper
50s near Lake Superior.
Tuesday, a dry airmass will prevail with sfc ridging building over
the region. Under mostly sunny skies through most of the day temps
will remain above normal with forecast soundings supporting highs in
the mid 70s. Mid and high clouds will gradually spread into the area
during the afternoon with the developing waa pattern in advance of a
trough over the plains.
.LONG TERM...(Tuesday night through Monday)
Issued at 330 PM EDT MON SEP 19 2016
Zonal flow aloft the middle of this week becomes much more amplified
the upcoming weekend as sharp ridge develops mid North America btwn
upper trough over eastern Canada and trough across western Conus. At
the sfc, a low pressure system and warm front emerging onto the
Central Plains on Wed will track over the Upper Great Lakes Wed night
into Thu. This system will bring best chance of widespread rain to
the region this week. An west to east frontal boundary and pwats over
1.25 inches lifting into the boundary along with area being situated
in right entrance region of upper jet over northern Ontario suggest
could be moderate or heavy rain. Since tighter h85 temp gradient and
edge of higher instability stays south of Upper Michigan closer to
the sfc low pressure system, may also see the heavier rain remain
south. Will keep featuring highest pops over south half of cwa. Even
as sfc low and stronger instability stay to the south of cwa, there
is weak elevated CAPE and near 0c SI/s to support some rumbles of
thunder later Wed into Wed night. Best chance would be over scntrl.
Highs in the midweek period should be mainly in the 60s.
Questions remain in how strong upper trough is over eastern Canada
Thu into Fri as a stronger trough would push the sfc front far enough
south to keep conditions dry Thu night into Fri. Models are going
back and forth on this. Latest consensus suggests though there may be
some lingering showers on Thu night, most of Fri would end up dry.
Temps through this period will be at or slightly below normal. Normal
highs are in the mid-upper 60s.
Appears that high pressure will then attempt to build southward from
Manitoba and northern Ontario Fri night into Sat resulting in mostly
dry weather. However, the GFS solutions over the last couple days,
at least the ones that are reasonable in terms of the projected
upper level pattern, do indicate there still could be some rain Fri
night into Sat morning, at least for west and southwest portions of
cwa. Latest GFS has trended drier though with only far west cwa
getting clipped by additional showers. ECMWF has trended steadily to
drier weather over most of the cwa but does keep some qpf over west
cwa. Based on the trends, will keep small chances for rain Fri night
over far west and southwest cwa. Dry weather should then hold most
of Sat into Sat night as high pressure, both sfc and aloft, remains
over the Great Lakes. Highs remain in the 60s. Lows Fri night and
Sat night will dip into the low 40s inland. One of these nights may
see even lower temps perhaps as low as upper 30s, but right now not
looking for any frost.
Next chance of rain with some small chances of tsra returns Sun into
Mon. Ridging moving east and approach of at least a piece of
shortwave trough energy from the Plains will support the increasing
rain chances. Given the strength of the ridging departing and drier
air could take some time for the rain to arrive on Sun. Model
consensus works for now owing to the quicker GFS and slower
ECMWF/GEM. Latest ECMWF has edged trough aloft farther east and
would support arrival of rain earlier on Sun. Highs both days
should stay in the 60s though if the rain for later in the weekend
is delayed could see temps make run toward low 70s on Sun over parts
of the cwa.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 721 PM EDT MON SEP 19 2016
Expect VFR conditions at all taf sites through the period.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 401 PM EDT MON SEP 19 2016
West winds should generally diminish to 25 knots tonight into Tue as
the pres gradient weakens with the Canadian low lifting farther ne
across Hudson Bay. Winds will diminish to less than 20 kts Wednesday
and remain blo 20 kts into Saturday under a weak pres gradient
across the Upper Lakes.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...07
MARINE...JLB
Area Forecast Discussion
National Weather Service SAN ANGELO TX
610 PM CDT MON SEP 19 2016
.AVIATION...
/00Z TAFS/
Expect VFR conditions at the terminals for the next 24 hours. A
few showers will be near the KJCT terminal through 01Z.
&&
.PREV DISCUSSION... /issued 337 PM CDT MON SEP 19 2016/
SHORT TERM...
(Tonight and Tuesday)
A cumulus field had developed over much of West Central Texas this
afternoon. HRRR and the Tech Tech WRF models indicate isolated
showers and thunderstorm mainly southeast of Mertzon...San Angelo...
Cross Plains line. These storms, if they occur, will be diurnal in
character, ending at sunset with loss of heating.
Continued warm temperatures remain in store Tuesday as the upper
ridge continues. Highs again are expected in the mid 90s, after
morning lows in the lower 70s.
04
LONG TERM...
(Tuesday Night through next Monday)
Above normal temperatures and dry conditions with clear to partly
cloudy skies will continue through Friday for our area, with the
upper high remaining our dominant influence. The upper level high
over Texas will shift east and build over the Mississippi Valley on
Friday, as a strong upper low enters the western CONUS and moves
into Utah. Low-level moisture will increase across our area on
Friday, with an increase in south-southeast winds.
The 12Z GFS and ECMWF continue to show a potentially wet pattern
for next weekend, more notably for the western half of our area.
While the 12Z GFS and ECMWF differ on the details of the pattern
evolution, both models show an upper low over the southwestern
CONUS. A series of shortwave disturbances are progged to rotate
through the base of the trough and move across West Texas and
western parts of the Southern Plains. This setup favors increased
chances of showers and thunderstorms, especially for the western
half of our area. We are carrying chance PoPs beginning Saturday
and continuing into next Monday. Still have uncertainty this far
out, as the track and strength of the upper low will play an
important role on our rain chances. Will continue to monitor model
trends with the forecast pattern and adjust PoPs accordingly. With
the anticipated rain chances and increased cloud cover, temperatures
are expected to be at least several degrees cooler next weekend
with highs in the 80s.
19
&&
.PRELIMINARY POINT TEMPS/POPS...
Abilene 72 95 71 93 / 5 0 0 0
San Angelo 72 96 70 93 / 20 0 0 0
Junction 71 96 69 93 / 20 0 0 0
Brownwood 71 95 70 93 / 20 5 0 5
Sweetwater 71 94 71 92 / 0 5 0 0
Ozona 71 94 69 92 / 10 0 0 0
&&
.SJT Watches/Warnings/Advisories...
None.
&&
$$
21
Area Forecast Discussion
National Weather Service Tucson AZ
845 PM MST MON SEP 19 2016
.SYNOPSIS...Moisture associated with decaying tropical system Paine
will bring scattered showers and isolated thunderstorms through
Wednesday. A drying trend will begin Thursday and continue into this
weekend. However, enough moisture should exist for a slight chance of
showers and thunderstorms east of Tucson.
&&
.DISCUSSION...KEMX WSR-88D depicted mainly 30-45 dBZ moving
northward 10-15 mph across western Pima County, the Tohono O`odham
Nation, and south central Pinal County at this time. The rest of
southeast AZ was mostly void of precip echoes. Rainfall amounts thus
far have been limited to trace amounts or just a few hundredths of
an inch.
Regarding Hurricane Paine, the National Hurricane Center advisory
number 9 issued at 8 PM PDT this evening stated that Hurricane Paine
was located at 23.8N/116.7W, or southwest of the Baja California
spur. Hurricane Paine was moving to the north-northwest at 13 mph.
Hurricane Paine was beginning to decrease in intensity, as maximum
sustained winds had decreased to near 80 mph. Rapid weakening is
forecast during the next day or so, and Paine is expected to weaken
to a tropical storm by Tuesday morning, then become a remnant low on
Wednesday.
Meanwhile, back across southeast Arizona, IR satellite imagery
depicted cloud tops to generally be cooling during the past hour or
so. Dewpoints at lower elevations valid 8 PM MST ranged from the
lower-mid 40s across eastern sections, and from the 50s-lower 60s
from the Tucson metro area westward into western Pima county. The
dewpoint jump at KTUS occurred after the 20/00Z KTWC sounding was
completed. The sounding total precip water value at that time was
0.89 inch, and increase of nearly one-quarter of an inch versus 12
hours earlier. The profile exhibited a nearly saturated column above
500 mb, though was still quite dry in the surface-600 mb layer.
Several HRRR solutions and the 20/00Z NAM12 suggest the best chance
of measurable rainfall the rest of tonight will be west of Tucson.
This scenario seems plausible given radar trends. However, still
believe that rain chances will gradually spread eastward by Tuesday
morning.
For this forecast update, only very minor adjustments were made to
PoPs through Tuesday afternoon. However, the gridded data weather
fields and lightning activity levels were adjusted to depict less
coverage of thunderstorms versus the previous forecast. Thus,
isolated to scattered showers mainly from Tucson westward the rest
of tonight along with a slight chance of thunderstorms. Scattered
showers and isolated thunderstorms to then prevail area-wide by
Tuesday afternoon and continuing into Tuesday evening. The threat
for widespread heavy rainfall appears to be very low. High temps
Tuesday are forecast to be mainly 5-10 degs cooler versus today.
Please refer to the additional sections for further detail.
&&
.AVIATION...Valid through 21/06Z.
Scattered -SHRA mainly west of KTUS the rest of tonight, then
scattered -SHRA spreading eastward across southeast Arizona Tuesday
into Tuesday evening. A few -TSRA will also occur, though less
coverage versus the -SHRA. Otherwise, cloud decks lowering to
generally 8k-12k ft msl by daybreak Tuesday and continuing into
Tuesday evening. Surface wind the rest of tonight mainly wly/nwly
10-15 kts, then variable in direction at 10-15 kts Tuesday. Aviation
discussion not updated for TAF amendments.
&&
.FIRE WEATHER...There is a chance of showers with a few
thunderstorms through Wednesday. A drying trend will start Thursday
and continue into this weekend. However, moisture will be sufficient
for a slight chance of showers and thunderstorms east of Tucson. 20-
foot winds will be mainly terrain driven less than 15 mph through
Wednesday, then westerly to southwesterly breeziness developing
Thursday and Friday afternoons.
&&
.PREV DISCUSSION /219 PM MST/...Moisture associated with tropical
system Paine located well west of the tip of Baja early this
afternoon will continue to stream northward into Arizona tonight and
Tuesday. Clouds have already been on the increase with regional
radars detecting rainfall just south of the International border.
Recent model solutions suggested that showers will start to develop
and spread into southern sections of the CWA this evening and tonight
with the initial moisture advection. Deeper moisture will move into
the region Tuesday, with more widespread showers and isolated
thunderstorms developing. Lingering moisture will interact with the
tail end of the system moving into the Great Basin around Thursday.
This will keep a chance of rain in the forecast through at least
Friday, mainly east of Tucson. Both the ECMWF and GFS models drop
this system farther south into Arizona over the weekend with rain
chances possible into early next week along with cooler
temperatures.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson
solution at this time. WPC extended forecast discussion also hints
at what both the EC and GFS are advertising, which is to separate
and stretch the upper trough with two distinct lows forming, one
ejecting out with the northern branch, and the other stuck in the
southern branch into New Mexico. So, the overall trend for showers
to fill in and overspread western and central ND Friday into
Friday night continues, with a potential dry slot punching up into
central ND Saturday, limiting precipitation amounts. A surface
cold front will sweep through Saturday night and Sunday with some
showers behind the front. Drier weather is forecast Sunday night
through Monday.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 300 AM CDT Tue Sep 20 2016
A vcsh has been included at KDIK/KBIS until around 12z Tuesday,
with a VCTS at KJMS from 13z-17z Tuesday. Although vfr cigs and
vsbys expected through 06z Wednesday, bkn mid level clouds will
impact all terminals through Tuesday morning before scattered
conditions are once again realized. Winds will generally remain
light and northeasterly.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...KS
LONG TERM...KS
AVIATION...KS
Area Forecast Discussion
National Weather Service Charleston SC
356 AM EDT Tue Sep 20 2016
.SYNOPSIS...
Unsettled weather will linger across the region through Friday as
a stationary front remains nearby. High pressure will build in
from the north over the weekend.
&&
.NEAR TERM /THROUGH TODAY/...
The weak cold front is moving slowly south across Southeast
Georgia early this morning and will cross the Altamaha River by
sunrise. Although the front will remain to the south today, a
moist environment featuring pwats 1.5 to 1.8 inches will remain in
place as a potent cut off low meanders along the South Carolina
coast. The proximity of this feature coupled with the likely
development of a southwest oriented resultant sea breeze and
possible differential heating boundaries, the development of
isolated to scattered showers/tstms is plausible. Expect a
relative greater coverage of convection to occur across the
central and eastern portions of the forecast area where low-level
convergence will be enhanced along the sea breeze. Pops will be
limited to 20-30% with most of a the upper forcing associated with
the cut off displaced across Eastern North Carolina. Locally
higher pops may eventually be needed as mesoscale and instability
trends become a bit more apparent.
The absence of any real post-frontal cold air advection and the
likelihood of some decent amount of isolation today suggests
afternoon temperatures will remain above seasonal normals.
Guidance has certainly exhibited a cool bias over the past 5-7
days, but expect highs to warm into the upper 80s for most
locations. Depending on how much insolation occurs, a few 90s can
not be completely ruled out, especially across Southeast Georgia.
&&
.SHORT TERM /TONIGHT THROUGH FRIDAY/...
Tonight: Somewhat unsettled weather will linger through the night
as the cut off low meanders nearby. A weak shortwave rotating
around the western periphery of the upper low could support a bit
more shower activity after midnight, especially across interior
Southeast South Carolina. The development of this feature is
uncertain, but there are certainly signals in the various members
of the 20/00z model suite. Will carry 40% across interior
Southeast Georgia with 20-30% pops elsewhere. Lows will range from
the lower 70s inland to the mid 70s at the beaches.
Wednesday through Friday: Aloft a weak cut off low will hover
over SC Wednesday and Thursday, then be absorbed into the overall
flow by Friday. At the surface, a weak stationary front will be
just offshore Wednesday and Thursday, dissipating by Friday. The
combination of these features along with plenty of moisture across
the region will lead to showers for the entire time period. Local
vorticity enhancements pivoting around the cut-off low in the
upper and mid levels will further enhance the rainfall, especially
over the Charleston tri-county area. Though, there is too much
uncertainty to nail down the timing and exact details of these
enhancements days in advance. Wednesday and Thursday should be
wetter than Friday, so POPs start out in the chance territory and
then trend downward into Friday. Surface and upper level dynamics
won`t be as favorable for as much coverage in showers on Friday.
But chance POPs remain in the forecast along the coast where PWATs
appear to be a bit higher. The severe threat remains low due to
the lack of significant instability. Persistent clouds and
precipitation will keep temperatures near normal.
&&
.LONG TERM /FRIDAY NIGHT THROUGH MONDAY/...
High pressure building from the north this weekend will try to trend
the general weather pattern drier. Though, the threat of afternoon
showers could remain along the immediate coast. Models hint at a
cold front approaching from the north on Monday, possibly moving
through late. Uncertainty is too high nearly a week out, so we`re
forecasting low POPs and will refine the forecast as we get closer.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
The cold front has cleared KCHS and will move through KSAV over
the next 2 hours. Could see a brief shower occur at KSAV as the
front pushes through, but long-duration impacts are unlikely. Will
have to watch for possible post-frontal low-stratus given moist
low-levels will remain place behind the front with clearing
skies. There should be enough wind to preclude significant fog
development. Best status potential looks to occur at KSAV based on
the latest RAP stratus parameters. Will include a tempo of low-end
MVFR roughly 11-13z to cover this, but latest RAP soundings
suggest a brief period of cigs near alternate minimums could
occur. Will monitor this carefully. At KCHS, satellite shows
stratus steadily expanding behind the front. Latest guidance has
shifted considerably and is now showing increased probabilities for
IFR cigs, possibly dropping as low as alternate minimums. Will
amend to show MVFR and monitor for possible inclusion of IFR or
lower.
Extended Aviation Outlook: Periods of showers and thunderstorms will
bring brief flight restrictions each afternoon through Friday.
&&
.MARINE...
Today: North to northeast winds will prevail across the marine
area as a cold front drops to the south. Winds will be 10 kt or
less with seas 1-3 ft.
Tonight: Expect similar conditions with slightly lower wind
speeds and seas.
Wednesday through Sunday: A stationary front will be just offshore
through Friday. Unsettled weather is expected across the coastal
waters during this time period with occasional lightning and brief
periods of increased winds and seas. However, overall wind and sea
conditions should remain well below Small Craft Advisory levels.
High pressure will start building into the area from the north over
the weekend.
Tropical Storm Karl is expected to intensify into a hurricane as it
approaches Bermuda late this week. Depending on its eventual
intensity and movement, swell could reach our beaches as early as
Friday or Saturday and cause an increased threat of rip currents
&&
.TIDES/COASTAL FLOODING...
Astronomical influences and general north/northeast winds could
produce shallow salt water flooding Tuesday, mainly along the
Charleston County coast.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
ST/MS
Area Forecast Discussion
National Weather Service Duluth MN
325 AM CDT TUE SEP 20 2016
.SHORT TERM...(Today through Wednesday)
Issued at 325 AM CDT Tue Sep 20 2016
A weak ridge of high pressure was over the Northland early this
morning. This high will move east today and a trough will move
into the region and act on a baroclinic zone to produce a strong
area of FGEN. Showers and a few thunderstorms were occurring over
portions of southwest to south central North Dakota into central
South Dakota as of 08Z and this is expected to move into portions
of the Northland this morning. We made some significant changes to
the forecast for today by increasing the chance for rain quite a
bit. The HRRR is most aggressive with rain coverage and if it
ends up being correct, we`ll have to increase the chance even
further and possibly spread further east into northern Wisconsin.
Highs today will be in the upper sixties to lower seventies.
The FGEN will weaken this evening and the area of rain should
diminish. A warm front will extend from low pressure in the
Central Plains northeast into southern Minnesota and southern
Wisconsin. The front will move little into Wednesday. A shortwave
will move along the frontal surface as well Wednesday along with
strengthening FGEN/WAA and cause showers and storms to increase
through the day, especially along and south of Highway 2 including
all of northwest Wisconsin.
.LONG TERM...(Wednesday night through Monday)
Issued at 325 AM CDT Tue Sep 20 2016
The area of low pressure will slowly move into the Central Plains
by Thursday as an inverted trough is located over central MN. The
main concern is where the heavier rain will fall. With the
shortwaves moving through the trough and the dynamics, it looks
like the heavier rain will be across NW WI based on past trends
and model forecast. Models are still different with the NAM
further north with the rainfall with the GFS further south and the
ECMWF a little closer to the GFS. Went with a GFS/ ECMWF
compromise for solution. Similar to previous shift, will not put
any potential flooding wording in for now until the situation can
be better defined.
There will be a break in the rain as the trough drifts south out of
the forecast area on Thursday. But the precipitation returns as the
warm front drifts back north Thursday night and Friday. It does
look like it could be decent amounts of rain with 0.25 to 0.50
possible. The upper level trough will move through the region
Saturday night through Sunday night with shortwaves passing through
the region. This will keep the threat of rain Sunday night.
Finally, it dries out on Monday as a ridge builds into the region.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1241 AM CDT Tue Sep 20 2016
High pressure will gradually lose its grip on the Northland, as
strong warm air advection pushes into the region from the south. A
warm front is expected to develop across central Minnesota on
Tuesday, with a few showers developing in the vicinity of the front.
Have included vicinity showers in the KBRD TAF for a time Tuesday
Morning. Conditions are expected to remain VFR throughout the period
at all sites.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 71 51 65 51 / 40 10 50 40
INL 70 46 64 43 / 10 10 10 10
BRD 71 53 67 52 / 50 10 70 40
HYR 74 53 68 54 / 20 20 70 70
ASX 73 54 66 52 / 10 10 50 60
&&
.DLH Watches/Warnings/Advisories...
WI...None.
MN...None.
LS...None.
&&
$$
SHORT TERM...Melde
LONG TERM...Stewart
AVIATION...Stewart
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
333 AM EDT Tue Sep 20 2016
.SYNOPSIS...
Weak low pressure will drift around Georgia and the Carolinas into
the second half of the week. An upper ridge will build over the
southeast states through next weekend as temperatures rise above
normal again.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 310 AM: RAP 500mb analysis shows cutoff low over central
VA/NC/SC, while sfc analysis shows low pressure just off Cape
Lookout. In conjunction with high pressure over the Northeast, a
moist easterly flow continues into the CWFA. Patches of stratocu
developed over parts of the CWFA earlier this AM as a result,
but these have thinned over the past hr or so. Some light fog
may still develop, but it is looking unlikely vsby issues will
be significant outside mtn valleys; dewpt depressions appear too
large over much of the Piedmont.
Today the CWFA will see the effects of the somewhat drier
continental airmass that pushed in behind the front yesterday. Lapse
rates are not as strong aloft. Convergent flow in the upper
levels (upstream of the low) is not supportive of widespread
convective development either. The paltry QPF response from the
hi-res guidance, particularly the NCEP WRF Windows, reflects these
findings. PoPs accordingly have been lowered quite a bit from the
previous forecast. I will retain chance-range values along/east
of I-77, where vort lobes encircling the low may pass through and
provide occasional enhancement to lift. Also a narrow band of
chances is maintained over the Blue Ridge, where several model
runs have initiated cells. Any activity will be capable of some
brisk outflow winds, but no severe weather is anticipated. Partial
thickness values have not changed much since Monday, and enough
sunshine should occur to easily bring temperatures back into the
upper 80s over most of GA/SC, with mid-80s likely across the NC
foothills/piedmont.
Tonight, models expect less low-level cloud cover will wrap around
the low, which may even begin to retrograde slightly. While models
produce little in the way of QPF this far west, seeing how a few
showers have managed to develop from time to time this morning,
a slight chance has been retained more or less over the eastern
half of the area. Min temps will again be a couple categories
above normal.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 245 AM EDT Tuesday...the latest model guidance has somewhat of
an eastward trend to the position of a closed upper low on
Wednesday, with the center closer to the coast than previous runs.
This position would keep the deeper moisture more to the east and
would back the flow a bit more over the fcst area, which would be
more unfavorable for precip over the mtns and near the Blue Ridge.
The fcst will generally follow this trend which is reflected mainly
in lowering the precip chances over the Mtns and Foothills and
delaying the development of precip from the east on Wednesday
morning. That being said, think Wednesday overall still has the best
chance for seeing precip, particularly over the Wrn Piedmont of NC
as rain that develops closer to the coast is wrapped westward.
Confidence not high enough to go above 50 pct yet. Will also not
completely rule out heavy rain over the eastern zones, but for the
time being the threat is low enough to not mention in the HWO.
Precip chances will have a diurnal peak late in the day but will not
completely diminish overnight as the upper low remains nearby into
Thursday and Thursday night. The model guidance now suggests that
drier air will be pulled in from the north on Thursday night which
should eliminate lingering precip, so precip chances diminish
accordingly. Temps should finally be kept to something closer to
normal for this time of year.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 315 AM Tuesday, the models remain in better agreement out in
the Medium Range with the fate of the upper low over the Carolinas,
opening it up and taking it off to the east on Friday. We retain a
chance of precip across most of the area mainly for Friday afternoon
with the possibility of scattered showers developing with weak
instability, mostly in deference to the ECMWF. The guidance shows
the upper pattern amplifying over the weekend with a ridge building
off to the west and an upper trof digging over the Northeast. The
resulting NW flow aloft is a dry pattern for the Wrn Carolinas,
especially at this time of year. The legacy of the slight chance PoP
was kept for Saturday afternoon, but most places will probably not
see rain. Precip chances were removed for the rest of the weekend.
Model agreement as to the passage of a back door cold front on
Sunday is not particularly great, with the ECMWF hanging the
boundary closer to our region and developing some precip for Monday.
No changes were made out that far to the precip chances because of
this uncertainty. However, the high temp fcst looks too cool based
on a blend of the guidance, so Monday max temps were raised at least
one category which pulls them up close to normal.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
At KCLT: Moist northeasterly flow around low pressure near the
Carolina coast is already bringing a fair amount of MVFR level
clouds to the Piedmont. Expect these clouds to expand and/or lower
as daybreak approaches; cigs are expected to remain MVFR at worst,
however. Conditions today will be less favorable for deep convection
than they were Monday, being as the area will be upstream of the
low. Still can`t rule out a stray shower or possibly even TS during
the heat of the afternoon. Could see some low clouds again tonight,
but think that will occur after 06z if at all.
Elsewhere: Patchy low VFR to MVFR cigs are expected to impact all
sites except KAND overnight, due to moisture wrapping around coastal
low pressure. MVFR fog may also develop in parts of the area,
namely mountain valleys and the more climatologically favored sites
in the Piedmont. Lapse rates will be weaker today than they were
Monday, and so convective precip coverage is expected to remain
isolated. KAVL receives VCTS with several convection-allowing
models developing activity along the Blue Ridge, but no other
mentions are made. N to NE flow continues thru the period.
Outlook: Drier air and mostly VFR conditions are expected Wednesday
and Thursday. However, an easterly flow may bring moisture back
from the Atlantic at times, especially late in the week. Periodic
restrictions could return Thursday and Friday, if not sooner.
Confidence Table...
07-13Z 13-19Z 19-01Z 01-06Z
KCLT Med 75% Med 78% High 100% High 100%
KGSP Med 71% High 92% High 100% High 100%
KAVL Med 67% Med 77% High 100% High 100%
KHKY Med 60% High 91% High 100% High 100%
KGMU Med 67% High 92% High 100% High 100%
KAND High 100% High 100% High 100% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...DEO
NEAR TERM...Wimberley
SHORT TERM...PM
LONG TERM...PM
AVIATION...Wimberley
Area Forecast Discussion
National Weather Service Lincoln IL
338 AM CDT TUE SEP 20 2016
.SHORT TERM...(Today and tonight)
ISSUED AT 338 AM CDT Tue Sep 20 2016
Another unseasonably warm day, with generally quiet conditions, is
expected across central and southeast Illinois. However, there is
one fly int the ointment with respect to the forecast. This revolves
around the chance for a few showers/storms as diurnal instability
builds and a weak surface boundary lies in our vicinity.
A weak west-southwest to east-northeast oriented cold front is
currently sinking across northern Illinois. While there is some
variance in the guidance, not surprising given the weak steering
flow, this boundary is likely to briefly stall out across central
Illinois later today before heading back north tonight. Have added
isolated showers/storms to portion of forecast area north of the I-
72 corridor this afternoon. This area resides within the peak
forecast instability axis (2000-4000 j/kg), is most likely to have
the front in the area, and is closer to the faster flow aloft. While
the coverage is likely to be very low, the risk of precipitation is
certainly not zero. The risk of rainfall should end with loss of
diurnal heating.
&&
.LONG TERM...(Wednesday through Monday)
ISSUED AT 338 AM CDT Tue Sep 20 2016
Forecast is warm and rather calm for the most part as the upper
ridge builds over the eastern half of the CONUS for the rest of the
week. A series of shortwave ripple through the flow aloft, but the
ridge deflects most of them north of ILX. Going further into the
extended for the weekend...the GFS has come around to last nights
ECMWF solution for the next system. Late Thursday/Friday, a trof
digs in over the west coast and settles into the SW. Now models
agreeing in a more cut off solution. Whereas the flow aloft does
become more southwesterly, the cut off low is much slower to make
any progress eastward. The energy in the northern stream is sheared
out a bit, and the front is dragged along behind it, separate from
the cut off low and weaker overall. The southern extent of the
precip is in question, and the last run is even more spotty with the
production of QPF this far south. The forecast at this point is
warm for mid September, and mostly dry, with chance pops to cover a
weak system this weekend.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 1149 PM CDT Mon Sep 19 2016
Convection along the approaching cold front has remained confined
to northern Illinois, with just a wind shift occurring along the
southern portion of the front approaching Galesburg at 0430z. The
front will continue to make slow progress into central IL from
the NW, but increasing clouds is looking more like the primary
impact, along with a wind shift. No storms are expected to affect
any of our terminal sites the rest of the night, and no precip
will be included in the 06z TAFs. The latest HRRR has dry
conditions for all our counties over the next 12 hours. The RAP
shows some showers developing just east of the IL river between
14z-16z Tuesday, but little support is evident in the other models
for that scenario. NAM and GFS forecast soundings continue to
show the potential for some MVFR ceilings for PIA and BMI late
tonight as the front pushes south through the area. Residual
boundary layer moisture could be enough for patch fog in low lying
areas, however, will not include any MVFR fog at any terminals.
Winds will start out from the south-southwest at 4-6kt, then
become variable as the front passes. Wind directions will shift
to the southeast tomorrow morning, with wind speeds tomorrow
generally remaining below 10kt.
&&
.ILX Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...Bak
LONG TERM...HJS
AVIATION...Shimon
Area Forecast Discussion
National Weather Service Marquette MI
526 AM EDT TUE SEP 20 2016
.SHORT TERM...(Today and tonight)
Issued at 525 AM EDT TUE SEP 20 2016
WV imagery and RAP analysis indicated a mainly zonal pattern across
the northern CONUS/Southern Canada with a 130 knot 250-300 mb
jet from the Northern Rockies into the Upper Great Lakes. A
shortwave upstream was producing a cluster of storms over the ND/SD
border along MUCAPE gradient approaching 1000 j/kg, steep mid-lvl
lapse rates and at nose of fairly strong 850 mb moisture transport.
Over the Upper Great Lakes broad sfc high pressure has resulted in
generally cloud-free skies early this morning. Early morning temps
have fallen into the 40s over the interior west half and into the
50s east half and along the Great Lakes shores.
Today, a dry airmass will prevail with sfc ridging in place over the
region. Under mostly sunny skies through most of the day temps will
remain above normal with forecast soundings supporting highs in the
mid 70s and perhaps even higher in a few spots. Mid and high clouds
will gradually spread into the area from the west during the afternoon
with a waa pattern developing in advance of a trough over the plains.
Tonight, Waa continues tonight with a northward push of 850 mb warm
frontal boundary into Northern Wi and expect clouds to increase into
Upper Mi. Models suggest convection could initiate along warm frontal
boundary over Nrn Wi with hint of a weak shortwave moving through the
area. Will include some slight chc pops for showers late tonight far
south central in case convection over Northern Wi brushes Wi Border
counties.
.LONG TERM...(Wednesday through Monday)
Issued at 432 AM EDT TUE SEP 20 2016
An increasingly amplified pattern will be developing across N
America for the remainder of this week. Ridge/positive height
anomaly currently moving across the Gulf of Alaska will strengthen
as it shifts across the Northwest Territories to Nunavut by the end
of the week. The magnitude of the positive height anomaly at 500mb
will reach 3 standard deviations above the long term late Sept avg.
To the s of this anomaly, a trof will amplify over the western CONUS
this week. Ahead of this developing western trof, shortwave energy
in the vcnty of southern CA will be kicked ne, reaching the western
Great Lakes Wed evening. This energy will bring the next opportunity
of widespread pcpn Wed into Thu. What happens late week and thru the
weekend continues to be uncertain. One aspect that has generally
been favored in the last day or so is for increased se Canada
troffing late week, which seems reasonable based on the strength of
the north central Canada positive height anomaly and based on this
anomaly linking up with the ridging farther s ahead of the western
CONUS trof. This argues for a drier period late week as sfc high
pres associated with the sharp ridge builds se into northern Ontario
and the Upper Great Lakes. Until that happens, right entrance of the
upper jet associated with the se Canada trof may continue to support
some shra into Fri. Over the weekend into early next week, attention
turns to the fate of the western CONUS trof. As CMC/GFS ensembles
and some operational medium range models began to show a day or so
ago, guidance is overall converging toward the solution of dropping
much of the energy in the western trof into the sw CONUS. Building
heights to the n of this feature will weaken/shift the mid continent
ridge e as a shortwave is forced se into the Upper Lakes late
Sun/Mon downstream of the building heights over the w. This will
provide the next good chc of shra. As for temps, after the recent
warmth, readings will be trending back to normal or a little blo
normal this week as fcst area ends up under low-level ne to e winds
btwn frontal boundary to the s and high pres building toward
northern Ontario. Coolest conditions may end up occurring early next
week behind the shortwave pushing thru the area late Sun/Mon.
Wed-Fri...shortwave energy lifting ne from the sw states ahead of
the deepening western CONUS trof will result in sfc frontal boundary
settting up from the Plains across the Great Lakes with weak low
pres waves rippling along it. Combination of shortwave energy, upper
divergence from right entrance of 120kt upper jet across northern
Ontario into Quebec, frontal boundary and precipitable water
increasing to around 1.25 inches will support pcpn development
across the Upper Mississippi Valley and Upper Great Lakes Wed into
Thu. Given avbl moisture, mdt/hvy rainfall is a possibility. Better
chc of the heavy rainfall will be s of the fcst area in WI, closer
to frontal boundary, but southern Upper MI could certainly see some
heavier rainfall at times. While 00z guidance has mostly trended
slower to push pcpn s of the area Thu into Fri, fcst will maintain
closer continuity to previous fcst in trending drier later Thu into
Fri. Pops will drop to low chc across the s into Fri while the n
trends to dry weather. Proximity of the right entrance of 120kt
upper jet leads to low confidence for the drying trend, but
eventually, sharp ridge thru central N America will support sfc high
pres building into the Upper Great Lakes, pushing pcpn s and w of
the fcst area.
Heading into Sat, the ECMWF is most aggressive with right entrance
of upper jet aiding renewed pcpn development back into Upper MI. For
now, confined chc pops to western Upper MI, in better aggreement
with the GFS/CMC.
Models show poor continuity in timing of the shortwave that reaches
the Upper Lakes early next week. Due to the inconsistencies, a
consensus of recent runs was utilized, resulting in chc pops
spreading across the area Sun/Sun night and lingering over the e on
Mon.
&&
.AVIATION...(For the 06Z TAFS through 06Z Tuesday night)
Issued at 140 AM EDT TUE SEP 20 2016
Expect VFR conditions at all taf sites through the period. West winds
will gust from 20-25 knots by late Tue morning into late afternoon,
strongest over the more exposed CMX site.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 525 AM EDT TUE SEP 20 2016
West southwest winds to 25 knots will diminish to 20 knots or less
tonight into Wed as the pres gradient weakens with the Canadian low
lifting farther ne across Hudson Bay. Winds will remain blo 20 kts
into Saturday under a weak pres gradient across the Upper Lakes. &&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Beach Hazards Statement until 2 PM EDT this afternoon for MIZ006.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...Rolfson
AVIATION...07/JV
MARINE...Voss
Area Forecast Discussion
National Weather Service Raleigh NC
413 AM EDT TUE SEP 20 2016
.SYNOPSIS...
An upper level low will become nearly stationary over the Carolinas
and consequently draw the remnant low of Julia southwestward along
the Southeast U.S. coast during the next several days. Moist,
northeasterly low level flow and unsettled conditions will result.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 400 AM Tuesday...
WV satellite imagery depicts an increasingly well-defined mid-upper
level low evolving over the west-central Carolinas this morning,
though the 00Z upper data indicate it had not yet closed off. Once
it does, strong upper divergence will develop in the deformation
zone of the low --over ERN NC-- as the low drifts SEWD across SC
during the next 12-24 hours. Meanwhile, KMHX radar and surface data
indicate the remnant ~1009 mb low of Julia continues to drift very
slowly NEWD this morning and was centered at 08Z between Cape
Lookout and Cape Hatteras NC.
The forecast models agree that the low will be drawn or elongated
SWWD toward the aforementioned upper low, but there remains larger
than average uncertainty with respect to both when and where that
turn will occur. This will have large ramifications on the risk of
flooding/how much rain falls over east-central NC through tonight,
since rain will be maximized immediately N of the track of the
surface low, where the associated moist isentropic upglide in ELY
flow there is drawn up and into the divergent deformation region of
the upper low.
Based on the current position of the low relative to model analysis
fields, a blend of the 00Z NAM/00ZGFS/06Z RAP is preferred, which
favors the low meandering near MHX for the next 24 hours,
characterized by a little more NEWD motion early today, followed by
a slow drift to the WSW tonight. This scenario would favor the
heaviest rain remaining E of the RAH CWA, with instead the expansion
of an area of moderate showers across the NE Piedmont and Coastal
Plain, and diurnal scattered showers and isolated storms over the
SRN-WRN Piedmont and Sandhills /on the WRN edge of a blanket of
overcast over the remainder of central NC/ where the presence of the
cold pool aloft accompanying the upper low will favor steeper lapse
rates and "instability" convection.
High temperatures will again be tempered by low and deep layer
cloudiness, and range from the mid 70s over the NE Piedmont/NRN
Coastal Plain to lower 80s from MEB to VUJ to INT, where periods of
sun are expected. The pressure gradient between post-tropical Julia
and high pressure over the OH Valley will also result in a noticeable
NELY breeze, strongest with gusts to 20-25 mph in the Coastal Plain.
Lows tonight in the upper 60s to lower 70s.
&&
.SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/...
As of 350 AM Tuesday...
Them remnant low from Julia is expected to drift back to the
southwest on Wednesday as it becomes fully merged with the upper low
cutting off over upstate SC this morning. The ECWMF and NAM are
in good agreement on this southwestward drift, while the GFS
continue to favor a more northward extension of the the low along
the coast. Good easterly moisture transport will continue on the northern
side of the low, tapping the 2-2.25" PW air off the coast and
maintaining a threat of scattered to numerous heavy showers. The
more southern ECMWF/NAM placement is preferred, which should
focus the greater coverage of showers and higher qpf across the
northern portions of the Piedmont and Coastal Plain. QPF is
generally forecast to be 0.5" to 1", though heavier localized
amounts are almost certain. Highs should be mostly in the
mid/upper 70s given cloud cover and showers.
Loss of heating should reduce the coverage of showers and leave
the greater coverage to the coastal areas and the inverted trough
left int he wake of Julia. However, the presence of moist easterly
flow and weakly diffluent flow aloft necessitates at least a
chance of showers overnight. Lows 66-71.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
As of 350 AM Tuesday...
The airmass over central NC will remain largely unchanged Thursday
and Friday, with PW still in the 1.5" to 2" range, though the
upper low over the Carolinas is expected to slowly shear out and
lose its forcing influence. Mainly diurnally driven showers should become
more widely scattered and pose less of a flash flooding threat as
the week wears on, with highs warming back into he mid 80s by
Saturday. The weakening upper low is then forecast to be swept
away by the stronger westerlies to our north as a deep trough
begins to dig across New England through the weekend. A cold front
is progged by noth the GFS and ECMWF to surge down the east Coast
Saturday and settle in the Southeast by Sunday/Monday, knocking
thicknesses below 1380, which would result in pleasant highs back
in the mid 70s early next week.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
As of 230 AM Tuesday...
NELY low level flow, around the remnant circulation of Julia now
centered near Cape Lookout, will wrap moisture SWWD across central
NC for the next several days, while an upper level low becomes
nearly stationary over the Carolinas during the same time. The
result will be a persistence forecast of continued sub-VFR ceilings,
lowest and most widespread each night, and periods of showers,
through the end of the week.
Through early tonight, widespread IFR-MVFR ceilings, whose WRN edge
will flirt with Triad terminals, will gradually lift and scatter to
VFR by this afternoon - first at Triad terminals and FAY/RDU, and
last, if at all, at RWI. An area of showers, some heavy, will also
expand over NERN NC and pivot SWWD and affect portions of central NC
later this morning through tonight, particularly at RWI/RDU/FAY.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...BS
LONG TERM...BS
AVIATION...MWS
Area Forecast Discussion
National Weather Service Blacksburg VA
358 AM EDT Tue Sep 20 2016
.SYNOPSIS...
An upper low combined with the remnants of former Tropical Storm
Julia will meander about eastern North Carolina and South Carolina
through late week before finally shifting out into the Atlantic
ocean. This will keep fairly unsettled conditions east of the Blue
Ridge over the next several days, less so in western areas. High
pressure will gradually build in from the west during the later
half of the week before a cold front approaches late in the
weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 330 AM EDT Tuesday...
A fairly complicated forecast through this period as a weak upper
low cuts off across the Carolinas. This upper low is combined from
the remnants of former T.S. Julia and an upper trough that cutoff
from the westerlies yesterday. Models continue to offer several
solutions as to how far west and north tropical moisture from
these combined systems will track back into the RNK CWA. The GFS
tends to be fairly dry keeping the associated rainfall closer to
the coast, while the NAM/Canadian/ECMWF spread the moisture much
further back west and north, all the way to the Blue Ridge. ECMWF
QPF is excessive, while the GFS is minimal at best. The concern,
however, is that the ECMWF, NAM, and Canadian are more similar in
QPF amounts, namely several inches as compared to the GFS. Having
said this, all models are in good agreement that more appreciable
rain will not spread back into the CWA until later today or this
evening. The HRRR and NCEP WRF models show little to no
precipitation making it any further west than the eastern parts of
the Piedmont today/this afternoon. Mid-level air spreading east
from the TN/OH valley is quite dry with mean RH less than 15%.
Therefore, in agreement with other offices, have decreased pops
for today/this afternoon, then increased into the high chance
range along RAH border after 00Z when a weak spiral band is
evident moving west into the region.
As always with this type of pattern of high tropical PWAT air
yielding an efficient warm rain process and enhanced upslope
easterly flow developing, there are concerns of enhanced, heavy
rainfall along the east slopes of the Blue Ridge. This will
certainly need to be watched over the next few days.
While we are almost a year to the date of a very heavy
rain/flooding event that evolved along the Blue Ridge in 2015,
the synoptic pattern this week is not similar. Several features in
place during the event last year are lacking at this time. We
lack a T.D. moving north out of the Gulf with PWATS in excess of
2.0 inches, an upper trough to the west, a stationary front over
the region, and strong easterly flow to the east of the front
thanks to a strong surface high over New England. So, at this
point, concerns are far less than at this time last year for such
type of event. Nonetheless, as noted above, we will need to keep a
close eye as the ECMWF/NAM/Canadian depict several inches of
rainfall across eastern NC very close to the RNK border and we are
dealing with remnants of a tropical storm, always problematic. The
key take away here is that confidence is low that the deep
tropical moisture from remnant Julia will ever make it this far
west. It is more likely to stay across the coastal plain in
association with the coastal trough.
As has been the case for weeks, no appreciable change in 850mb
temps noted through the forecast period. Temperatures will largely
be dependent on cloud cover today, less in the west, more in the
east. This will most likely yield max temps in the upper 70s to
lower 80s with lows in the upper 50s to mid 60s. These
temperatures are 5-10 degrees above normal, especially min
temperatures.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
As of 315 AM EDT Tuesday...
During this portion of the forecast, a frontal boundary will remain
stalled from near Jacksonville, FL, northeast along the east coast
to the Outer Banks of North Carolina. A closed upper low will
meander north and south along this boundary, and be centered
somewhere near the coast of South Carolina.
Model guidance varies as to the degree to which moisture on the
northern side of this system gets advected into parts of our region.
The GFS is the driest with little if any precipitation impacting our
area. The ECMWF, NAM, and Canadian solutions all to some degree
offer solutions that have precipitation impacting roughly the
southern third of the region, with the greatest concentration
across the southeast parts of the area. WPC also has been leaning
towards this wetter scenario as noted in their QPF forecasts.
Our ongoing forecast has been been mirroring these wetter solutions,
and the one from this morning will continue likewise. The biggest
alteration will be a slight shift southeast of the northern most
extent of the slight chance probabilities. Other than that, the
general orientation of the precipitation in the forecast has been
altered very little.
By Friday into Friday night, the guidance is in fairly good
agreement that the closed low will transition into an open wave and
start to progress more out to sea. This process will allow for a
decrease in coverage across the southern sections of the area. By
late Friday night, all the precipitation is expected to be out of
the area.
Thanks to decreasing wind speeds, less cloud cover, and a moist
boundary layer, late night and early morning river and mountain
valley fog is expected, especially by Thursday night and Friday
night.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
As of 330 PM EDT Monday...
The weak closed 500mb low opens to become absorbed in the general
west to east flow which gradually takes the clouds and rain east and
off the Atlantic coast Friday night.
Upper ridge strengthens by Saturday morning but remains undercut by
low level southeast flow Saturday ahead of a shallow backdoor front
that may slide south into the area by Sunday. This supports isolated
diurnal pops Saturday before deeper upstream moisture ahead of a
stronger Midwest cold front works east along the backdoor boundary
resulting in perhaps more widespread showers by early next week.
Leaned temperatures towards Superblend with cooler readings
especially for Sunday and Monday with moderating high
temperatures for Tuesday.
&&
.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
As of 145 AM EDT Tuesday...
With the combination of now a moist ground and lingering low
level moisture, look for a continuation of an increase in coverage
of LIFR/IFR ceilings across the mountains with IFR/MVFR ceilings
east of the crest of the Blue Ridge. Visibilities will also
continue to trend downward. LIFR/IFR values with fog/mist are
expected across the mountains, especially the river valley
regions. Areas east of the Blue ridge will more likely remain on
the low end of VFR or drop into the MVFR range.
Sub-VFR conditions are expected to improve to VFR within the
14Z-16Z/10AM-noon time window. Drier air will continue to work its
way into the region through Wednesday afternoon. Light winds and
surface moisture will help regenerate some sub-VFR visibilities in
the mountain valleys towards the end of the TAF valid time period,
06Z/2AM Wednesday.
Extended aviation discussion...
Tuesday night through Friday, outside of late night/early morning
fog/low clouds, expect mainly VFR conditions with the caveat to
this being any lingering slight chance of showers and
thunderstorms from Julia per GFS/EC, mainly affecting areas east
of the Blue Ridge.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...RAB
NEAR TERM...AMS/RAB
SHORT TERM...KK
LONG TERM...KK
AVIATION...AMS/DS/MBS
Area Forecast Discussion
National Weather Service Duluth MN
920 AM CDT TUE SEP 20 2016
.UPDATE...
Issued at 920 AM CDT Tue Sep 20 2016
Light rain was spreading into the Brainerd Lakes area per
observations and latest radar. Current indications are that these
showers will spread as far east as northwest Wisconsin this
morning, then lift northward this afternoon before diminishing
late. This rain is in conjunction with the vorticity max moving
along the North and South Dakota borders. The rain is benefiting
from some frontogenesis as well. Made some adjustments to
pops/weather and increase sky cover.
&&
.SHORT TERM...(Today through Wednesday)
Issued at 325 AM CDT Tue Sep 20 2016
A weak ridge of high pressure was over the Northland early this
morning. This high will move east today and a trough will move
into the region and act on a baroclinic zone to produce a strong
area of FGEN. Showers and a few thunderstorms were occurring over
portions of southwest to south central North Dakota into central
South Dakota as of 08Z and this is expected to move into portions
of the Northland this morning. We made some significant changes to
the forecast for today by increasing the chance for rain quite a
bit. The HRRR is most aggressive with rain coverage and if it
ends up being correct, we`ll have to increase the chance even
further and possibly spread further east into northern Wisconsin.
Highs today will be in the upper sixties to lower seventies.
The FGEN will weaken this evening and the area of rain should
diminish. A warm front will extend from low pressure in the
Central Plains northeast into southern Minnesota and southern
Wisconsin. The front will move little into Wednesday. A shortwave
will move along the frontal surface as well Wednesday along with
strengthening FGEN/WAA and cause showers and storms to increase
through the day, especially along and south of Highway 2 including
all of northwest Wisconsin.
.LONG TERM...(Wednesday night through Monday)
Issued at 325 AM CDT Tue Sep 20 2016
The area of low pressure will slowly move into the Central Plains
by Thursday as an inverted trough is located over central MN. The
main concern is where the heavier rain will fall. With the
shortwaves moving through the trough and the dynamics, it looks
like the heavier rain will be across NW WI based on past trends
and model forecast. Models are still different with the NAM
further north with the rainfall with the GFS further south and the
ECMWF a little closer to the GFS. Went with a GFS/ ECMWF
compromise for solution. Similar to previous shift, will not put
any potential flooding wording in for now until the situation can
be better defined.
There will be a break in the rain as the trough drifts south out of
the forecast area on Thursday. But the precipitation returns as the
warm front drifts back north Thursday night and Friday. It does
look like it could be decent amounts of rain with 0.25 to 0.50
possible. The upper level trough will move through the region
Saturday night through Sunday night with shortwaves passing through
the region. This will keep the threat of rain Sunday night.
Finally, it dries out on Monday as a ridge builds into the region.
&&
.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 632 AM CDT Tue Sep 20 2016
VFR through the forecast period at all TAF sites. However, there
could be some showers developing this afternoon at all airports
except HYR due to an upper level disturbance moving through the
region. For tonight...there could be some more showers at HYR and
BRD.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 70 51 65 51 / 40 10 50 40
INL 70 46 64 43 / 10 10 10 10
BRD 70 53 67 52 / 60 10 70 40
HYR 73 53 68 54 / 20 20 70 70
ASX 73 54 66 52 / 40 10 50 60
&&
.DLH Watches/Warnings/Advisories...
WI...None.
MN...None.
LS...None.
&&
$$
UPDATE...GSF
SHORT TERM...Melde
LONG TERM...Stewart
AVIATION...Stewart
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1033 AM EDT Tue Sep 20 2016
.SYNOPSIS...
Weak low pressure will drift around Georgia and the Carolinas into
the second half of the week. An upper ridge will build over the
southeast states through next weekend as temperatures rise above
normal again.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 1035 AM EDT: We have held onto valley fog in the western North
Carolina mountains until late morning, and issued SPS products for
areas of patchy dense fog. Meanwhile added a bit more cloud cover in
our eastern zones, plus gustiness over the entire region. Winds were
based on current observation and radar profiles.
Meanwhile the RAP 500mb analysis shows cutoff low over the heart of
the Carolinas, while sfc analysis shows low pressure just off Cape
Lookout. In conjunction with high pressure over the Northeast, a
moist easterly flow continues into the CWFA. Today we will see the
effects of the somewhat drier continental airmass that pushed in
behind the front yesterday. Lapse rates are not as strong aloft.
Convergent flow in the upper levels (upstream of the low) is not
supportive of widespread convective development either. The paltry
QPF response from the hi-res guidance reflects these findings. Also
the 06z NAM flavors have trended toward even less coverage than the
previous runs. I backed off PoPs a bit more with this update.
However I retained chance-range values along/east of I-77, where
vort lobes encircling the low may pass through and provide
occasional enhancement to lift. Any activity will be capable of some
brisk outflow winds, but no severe weather is anticipated. Partial
thickness values have not changed much since Monday, and enough
sunshine should occur to easily bring temperatures back into the
upper 80s over most of GA/SC, with mid-80s likely across the NC
foothills/piedmont.
Tonight, models expect less low-level cloud cover will wrap around
the low, which may even begin to retrograde slightly. While models
produce little in the way of QPF this far west, seeing how a few
showers managed to develop from time to time late Monday night,
a slight chance has been retained more or less over the eastern
half of the area. Min temps will again be a couple categories
above normal.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 245 AM EDT Tuesday...the latest model guidance has somewhat of
an eastward trend to the position of a closed upper low on
Wednesday, with the center closer to the coast than previous runs.
This position would keep the deeper moisture more to the east and
would back the flow a bit more over the fcst area, which would be
more unfavorable for precip over the mtns and near the Blue Ridge.
The fcst will generally follow this trend which is reflected mainly
in lowering the precip chances over the Mtns and Foothills and
delaying the development of precip from the east on Wednesday
morning. That being said, think Wednesday overall still has the best
chance for seeing precip, particularly over the Wrn Piedmont of NC
as rain that develops closer to the coast is wrapped westward.
Confidence not high enough to go above 50 pct yet. Will also not
completely rule out heavy rain over the eastern zones, but for the
time being the threat is low enough to not mention in the HWO.
Precip chances will have a diurnal peak late in the day but will not
completely diminish overnight as the upper low remains nearby into
Thursday and Thursday night. The model guidance now suggests that
drier air will be pulled in from the north on Thursday night which
should eliminate lingering precip, so precip chances diminish
accordingly. Temps should finally be kept to something closer to
normal for this time of year.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 315 AM Tuesday, the models remain in better agreement out in
the Medium Range with the fate of the upper low over the Carolinas,
opening it up and taking it off to the east on Friday. We retain a
chance of precip across most of the area mainly for Friday afternoon
with the possibility of scattered showers developing with weak
instability, mostly in deference to the ECMWF. The guidance shows
the upper pattern amplifying over the weekend with a ridge building
off to the west and an upper trof digging over the Northeast. The
resulting NW flow aloft is a dry pattern for the Wrn Carolinas,
especially at this time of year. The legacy of the slight chance PoP
was kept for Saturday afternoon, but most places will probably not
see rain. Precip chances were removed for the rest of the weekend.
Model agreement as to the passage of a back door cold front on
Sunday is not particularly great, with the ECMWF hanging the
boundary closer to our region and developing some precip for Monday.
No changes were made out that far to the precip chances because of
this uncertainty. However, the high temp fcst looks too cool based
on a blend of the guidance, so Monday max temps were raised at least
one category which pulls them up close to normal.
&&
.AVIATION /15Z TUESDAY THROUGH SATURDAY/...
At KCLT: Lower clouds moving into KCLT from the east. That trend
should continue for the remainder of the morning. As a result we
have updated the site for MVFR CIGS through the morning, with the
CIGS lifting somewhat in the afternoon. That will be another issue
to look at, based on bufkit data. We have also added gustiness to
the KCLT TAF site, based on TCLT profiles and surrounding
observations.
Still can`t rule out a stray shower during the heat of the
afternoon, but lapse rates are too poor for TS chances to warrant
any mention. That low will remain essentially stationary thru
tonight, but guidance has backed off earlier expectations of low
clouds and moisture wrapping around it. Precip chance tonight is
unmentionably low, and clouds look most likely to remain VFR. Winds
will steadily be in the NE quadrant.
Elsewhere: Except for fog in the mountain valleys and foothills,
no restrictions are expected this morning (even at KAVL). Lapse
rates will be weaker today than they were Monday, and so convective
precip coverage is expected to remain isolated. Latest round of
guidance, including the meso models, has trended toward even less
coverage than yesterday evening`s runs. Best chance is along the
Blue Ridge, hence VCSH at KAVL. N to NE flow continues thru the
period. Tonight, per guidance, fog is expected to return in the
same areas as this morning. A low VFR cloud deck may begin to
spread in from the east late.
Outlook: Drier air and mostly VFR conditions are expected Wednesday
and Thursday. However, an easterly flow may bring moisture back
from the Atlantic at times, especially late in the week. Periodic
restrictions could return Thursday and Friday, if not sooner.
Confidence Table...
14-20Z 20-02Z 02-08Z 08-12Z
KCLT High 100% High 100% High 100% High 100%
KGSP High 100% High 100% High 100% High 100%
KAVL High 100% High 100% High 100% High 91%
KHKY High 100% High 100% High 100% High 100%
KGMU High 100% High 100% High 100% High 100%
KAND High 100% High 100% High 100% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...None.
SC...None.
&&
$$
SYNOPSIS...DEO
NEAR TERM...TS/Wimberley
SHORT TERM...PM
LONG TERM...PM
AVIATION...TS/Wimberley
Area Forecast Discussion
National Weather Service Wilmington NC
1119 AM EDT Tue Sep 20 2016
.SYNOPSIS...
The remnants of Julia will remain across eastern North Carolina
through much of the week and this will keep the weather rather
unsettled. High pressure will build into the area by the weekend
finally bringing drier conditions. A cold front will move across
the area during Sunday bringing the first hint of Autumn early
next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 10 AM Tuesday...An upper low spinning around in the Carolinas
will continue to provide unsettled weather across the area through
tonight. Low clouds and spotty light drizzle were covering much of
the area this morning. A moist northerly flow was wrapping around
the remnant low from Julia as some drier air aloft wraps around
the back of the upper low. Sounding data and time height sections
show drier air aloft from h70 and above which looks like it should
mix down some later this afternoon especially across inland areas
producing some breaks in the clouds. This all makes for a tricky
forecast as the clouds will hamper heating and therefore
instability while areas that see some sunshine will become more
unstable and should see some convective development this aftn. The
cool pool aloft will drift south over the area helping to sharpen
lapse rates and promote some convection associated with
differential heating or low level convergence. It looks like the
best upper level energy and support will be aligned from the Cape
Fear almost due north and wrapping around the back end across
inland areas later today, while the best convergence associated
with sfc and low levels this morning will translate down across
mainly inland areas later today in N-NW flow on back end of sfc
low as it gets pulled S-SW toward Cape Fear. HRRR shows pcp mainly
aligned along I-95 corridor and west with only spottier pcp to
the east closer to the coast.
Temps struggling to make it into the mid 70s through this morning
will continue a slow rise hampered by clouds and pcp. Temps will
remain in the 70s most of the afternoon.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 300 AM Tuesday...Showery weather with moderate rainfall
this period as the cool pool aloft remains overhead. Higher
precipitable water and heavier rainfall potential will reside
north and west of the area from central SC to central NC to the
Outer banks, so the flooding threat lessens over NE SC and SE NC
this 2 day period. Temperatures to run near normal. Isolated TSTMS
will be possible anytime with help of a low level trigger given
the anticipated mid level lapse rates and available column
mositure.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 300 AM Tuesday...The upper cutoff low meandering across the
Carolinas leading up to this period, will finally weaken early
Friday and actually open up and picked up by the upper westerlies
ie. the jetstream, as they dip slightly southward. This a result
of the upper ridge amplifying across the central U.S. leading up
to Friday. During Friday thru Monday, this upper ridge will
further amplify, further dropping the upper westerlies southward.
The progged amplified upper trof line will reside well off the
east coast leaving the ILM CWA nearly halfway between the central
U.S. upper ridge axis and the trof line well off the East Coast.
At this location, models indicate the ILM CWA will likely see the
passage of a sfc cold front dropping north to south during Sunday.
This followed by a 1025 mb sfc High dropping to the area on
Monday. As for pcpn chances, will indicate isolated to scattered
at 15 to 25 POPs, for both Fri and Sat, and mainly sea breeze
force driven. For Sunday, will indicate 30-40 POPs tied to the
cold frontal passage. Models do not indicate any decent to strong
mid-level s/w accompanying this cfp, thus why kept POPs at this
range. As for Max/Min temps, basically blended/meshed the big 3
model Mos Guidance across the FA. This results in the ILM CWA 1
to 2 categories above climo norms for Fri and Sat...and at or 1
category below climo norms for Sun and Mon.
An elevated rip current threat will occur Fri thru the weekend due
to a 10 to 12 second period 2 to 4 foot ese ground swell
generated by Tropical Cyclone Karl affecting the area beaches.
&&
.AVIATION /13Z TUESDAY THROUGH SATURDAY/...
As of 06Z...Through 15-16Z there is high confidence of IFR at
coastal terminals. Otherwise 1-2K MVFR cigs expected. Shower
activity is offshore, but some patchy -dz/-ra could still occur
through mid-morning. Winds will be NW-N 5-10 kt.
MVFR cigs will lift to 2-3K by afternoon. Early to mid-afternoon
some VFR will occur, highest confidence at KFLO/KLBT. A cold pool
aloft and the days heating will support the development of
convection this afternoon. ATTM it appears coastal terminals will
have a better chance of VCSH with the best potential for
precipitation/thunderstorms at KFLO/KLBT mid-late afternoon into
the evening.
A moist N flow but lighter wind speeds support the development of
IFR at the terminals overnight. Cigs could possibly lower to LIFR
at the northern terminals.
EXTENDED OUTLOOK...Isolated to scattered afternoon and early
evening convection possible underneath the cutoff upper low
through Friday. MVFR/IFR morning stratus/fog possible each day
thru Saturday.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 10 AM Tuesday...E waves of 2-3 feet every 6-7 seconds will
move ashore today and tonight. Scattered heavy showers and
isolated TSTMS will remain in the marine forecast, so radar
updates are advised before a venture out today and tonight. NW
winds less than 15 KT will prevail today and tonight as low
pressure remains between Cape Lookout and Cape Fear, thus largest
seas and highest winds offshore.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 300 AM Tuesday...Changeable but overall light winds
Wednesday outside of showers or TSTMS, as weak low pressure
circulates over the waters. By Thursday, high pressure building
from the north will begin to force the low southward, bringing a
10-15 knot NE wind Thursday across the 0-20 nm waters. Radar
updates are recommended this period as showers and few storms
develop and roam the waters. SE swell will build close to 3 feet
by late Thursday.
LONG TERM /FRIDAY THROUGH SATURDAY/...
As of 300 AM Tuesday...Majority of this period will experience a
rather diffuse pressure pattern and relaxed gradient. Will attempt
to identify and use the best or predominate wind directions this
period. The exception will be during each afternoon thru early
evening nearshore, where a resultant wind boundary or sea breeze
should occur with se-s wind directions and speeds 10 to possibly
15 kt. The strength of the sea breeze circulation will depend how
warm inland temps reach during each aftn. Late Saturday night, a
cold front will be dropping down from the north and will be on the
doorsteps of the ILM coastal waters. It`s also noted that Tropical
Cyclone Karl will be making it`s hard right hand turn with Bermuda
on its mind.
Significant seas will run 3 to 4 ft Fri thru Sat with the
majority of it coming from a ground swell at 10 to 12 second
periods generated by distant Hurricane Karl. This illustrated by
the latest Wavewatch3 and locally run Swan models. Will see
afternoon wind chop on-top of this swell.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
NEAR TERM...RGZ
SHORT TERM...MJC
LONG TERM...DCH
AVIATION...MRR
Area Forecast Discussion
National Weather Service Lincoln IL
938 AM CDT TUE SEP 20 2016
.UPDATE...
Issued at 938 AM CDT Tue Sep 20 2016
Little change needed to the existing forecast. Weak cold front
dropping southward and hard to pick out on the surface obs over
central Illinois at the moment, but should the HRRR focuses it
along the I-72 corridor by late morning with little additional
movement. RAP model continues to ramp CAPE`s up to over 2000 J/kg
by midday, and between the instability and the front, the
potential continues for isolated storms this afternoon.
Temperatures are on track to reach the mid 80s in most areas with
some locally higher values.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 338 AM CDT Tue Sep 20 2016
Another unseasonably warm day, with generally quiet conditions, is
expected across central and southeast Illinois. However, there is
one fly in the ointment with respect to the forecast. This
revolves around the chance for a few showers/storms as diurnal
instability builds and a weak surface boundary lies in our
vicinity.
A weak west-southwest to east-northeast oriented cold front is
currently sinking across northern Illinois. While there is some
variance in the guidance, not surprising given the weak steering
flow, this boundary is likely to briefly stall out across central
Illinois later today before heading back north tonight. Have added
isolated showers/storms to portion of forecast area north of the I-
72 corridor this afternoon. This area resides within the peak
forecast instability axis (2000-4000 j/kg), is most likely to have
the front in the area, and is closer to the faster flow aloft. While
the coverage is likely to be very low, the risk of precipitation is
certainly not zero. The risk of rainfall should end with loss of
diurnal heating.
.LONG TERM...(Wednesday through Monday)
ISSUED AT 338 AM CDT Tue Sep 20 2016
Forecast is warm and rather calm for the most part as the upper
ridge builds over the eastern half of the CONUS for the rest of the
week. A series of shortwave ripple through the flow aloft, but the
ridge deflects most of them north of ILX. Going further into the
extended for the weekend...the GFS has come around to last nights
ECMWF solution for the next system. Late Thursday/Friday, a trof
digs in over the west coast and settles into the SW. Now models
agreeing in a more cut off solution. Whereas the flow aloft does
become more southwesterly, the cut off low is much slower to make
any progress eastward. The energy in the northern stream is sheared
out a bit, and the front is dragged along behind it, separate from
the cut off low and weaker overall. The southern extent of the
precip is in question, and the last run is even more spotty with the
production of QPF this far south. The forecast at this point is
warm for mid September, and mostly dry, with chance pops to cover a
weak system this weekend.
&&
.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 640 AM CDT Tue Sep 20 2016
Predominantly VFR aviation weather conditions are expected across
the central Illinois terminals through the 12Z TAF valid time. A
weak frontal boundary will be over part of the area today,
possibly triggering an isolated shower or storm. While KPIA and
KBMI are the most likely to be impacted by any convection, the
expected coverage is too low to mention at this time.
&&
.ILX Watches/Warnings/Advisories...
NONE.
&&
$$
UPDATE...Geelhart
SHORT TERM...Bak
LONG TERM...HJS
AVIATION...Bak
AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
901 AM PDT TUE SEP 20 2016
...Marine discussion and Synopsis updated...
.SYNOPSIS...
The moisture from Tropical Storm Paine will bring possible showers
and thunderstorms into this evening for Los Angeles and Ventura
Counties. Then another low will move in midweek for a temperature
cool down and increase the overnight marine layer. The offshore
flow will increase this weekend for a rapid jump in temperatures
and decreasing clouds.
&&
.SHORT TERM...(TDY-THU)
A fairly quiet morning in respect to precipitation across the
forecast area. Most of the showers have remained to the south and
over the adjacent coastal waters with no thunderstorms to speak
of. The synoptic pattern looks quite interesting today. Tropical
Storm Paine was located around 500 miles south of San Diego just
off the Central Baja Coast. By the looks of the latest Water vapor
and IR radar, Paine has become much less organized than earlier
this evening. Some remnants from Paine have been pulled north in
part from a weakening upper low that was located around 250 miles
west of San Diego. As the upper low continues to weaken, the mid
level moisture will not continue to drive north around the low,
but will start to re-direct to the north-northeast.
Based on models including the latest HRRR model, have pulled pops
out of all counties N of Los Angeles County this morning through
this afternoon. Except will keep slight chance of thundershowers
in the Ventura County Mtns this afternoon due to some marginal
instability. The conveyer belt of mid level moisture will now be
aimed towards the very southern part of the sate with the northern
most progression over portions of Los Angeles County through early
this evening. There are no real features that indicate any reason
to keep thunderstorms in the forecast for coast and valleys of Los
Angeles County this morning. There was a difluent area between the
remnants of Paine and the weak upper low that appeared on
satellite to show some cloud tops cooling near Catalina and
towards Orange County, but nothing has materialized. Therefore will
only be looking for isolated showers today for coast and valleys
of LA county. Have left slight chance for thunderstorms across the LA
and VTU county mountains this afternoon and Antelope Valley. The
latest NAM WRF soundings indicated some marginal convective
parameters as well as a vort max that skirts LA county and areas
to the south late afternoon hours. If isolated thunderstorms do
initiate over the L.A. county mountains, steering winds will be
fairly weak this afternoon which could cause some localized
street flooding.
By this evening the upper low that was just off our coast will
weaken and fill in as a more prominent upper trough begins to
move into Northern Cal. The southerly flow that brought up the
moisture will become more SW later this afternoon which will help
to dry out the atmosphere for the most part.
High temps will drop 5 to 8 degrees today across inland areas and
only a few degrees or about the same as yesterday for most
coastal areas. This due to clouds and the upper ridge beginning to
break down in response to the upper trough to the north. Low
clouds will likely redevelop across the Central Coast and Santa
Ynez Valley tonight into Wed morning. For Wednesday, expect
additional cooling as the upper trough approaches and increases
onshore flow. There will be a few flat cu across the LA and VTU
county Mtns but not expecting any showers to develop as soundings
indicating some warming aloft over the mtns to hamper vertical
development. Gusty NW winds will strengthen across the outer
waters which in turn will help an eddy to form. This will bring
low clouds well into the coastal valleys by Wed night while the
SBA S Coast stays mostly clear. Some stratus could form near SBA
city near Sunrise Thursdsay.
Cooler air will advect down the coast in response the upper
trough. Mostly NW flow will occur for SLO/SBA counties with
cyclonic flow remaining across LA/VTU counties. This will cause
low clouds to linger into the early afternoon across the LA/VTU
coastal areas while gusty west to north winds develop across the
Mtns and Antelope Valley. Thursday will be the coolest day this
week with highs mainly in the 70s to lower 80s inland, and cooler
at the beaches. The upper trough axis will move through Thursday
evening. An interesting pattern will be setting up for the long
term forecast.
Lastly, in regards to the Canyon Fire...There will continue to be
areas of smoke in and around the Central Coast. however onshore
flow will increase today sending the smoke across interior areas
and with some NW flow aloft should drift towards the SBA South
Coast this evening. More W TO NW flow will occur in the next
couple of days so smoke could reach portions of Ventura County
Coast and Valleys By Wednesday due to NW flow expected. If fire
continues into the weekend, expect offshore flow to blow smoke out
to sea.
.LONG TERM...(FRI-MON)
After a cooler than normal day on Thursday, The weather pattern
takes a major change as the upper trough (Inside Slider) moves
into NV/Utah Friday.
Initially gusty Sundowner winds across SBA county and northerly
winds will strengthen across the I-5 Corridor, Santa Clarita and
San Fernando Valleys and possibly into West LA Thursday evening
into Friday morning. Winds will then shift to the NE Friday and
continue through the weekend as relatively strong surface
pressure sets up over NV/UT. The offshore pressure gradient will
peak both Sat/Sun mornings allowing for our first moderate Santa
Ana wind event. Winds will be at least 5-15 mph stronger than
what we saw with the offshore event this last weekend and likely
even more so for coast/valleys. Wind advisories will likely be
needed this weekend for the usual wind prone areas of LA/VTU
counties. The combination of gusty winds, high temperatures, low
humidities and dry fuels will bring an elevated fire weather
concern this weekend.
High temps will be 2 to 6 degrees warmer on Friday across the
board, with an additional 8 to 15 degrees warmer on Saturday.
Highs will soar with combination of a moderate surface offshore
gradient and a relatively strong upper ridge overhead. Highs will
likely reach the mid to upper 90s with a few triple digits across
coastal valleys while the Antelope Valley only reaches the mid
80s. Coastal areas of LA/VTU counties will reach the upper 80s to
around 90. At this time, Sunday looks to be the hottest day as
gusty Santa Ana winds and high temps should reach up to 105 in the
warmest valleys and in the 90s along coastal areas. The Central
Coast should reach the 80s as well with weaker offshore flow. Low
clouds will not be an issue while the offshore flow persists.
Some cooling is likely on Monday as the offshore gradients begin
to weaken. This will allow for some cooling along the coast, but
high temps will remain well above normal on Monday.
&&
.AVIATION...20/0940Z...
At 0930Z, the marine inversion at KLAX was surface based. The top
of the inversion was 1300 feet with a temperature of 26 degrees
Celsius.
Overall, moderate to high confidence in 12Z TAF package. With
abundant mid-level moisture moving overhead, conditions should
remain VFR at all sites through this evening with a slight chance
of showers/thunderstorms across the LA county TAF sites through
this evening. For tonight, moderate confidence in return of
IFR/VLIFR conditions to the Central Coast and conditions remaining
VFR south of Point Conception.
KLAX...moderate confidence in 12Z TAF. VFR conditions are
anticipated through the TAF period. There is a slight chance of
TSTMs through this afternoon.
KBUR...moderate confidence in 12Z TAF. VFR conditions are
anticipated through the TAF period. There is a slight chance of
TSTMs through this afternoon.
&&
.MARINE...20/830 AM...
There is a slight chance of thunderstorms through this afternoon
for the coastal waters south of the Channel Islands.
For the outer waters... winds and seas will remain below Small
Craft Advisory (SCA) levels through tonight. Northwest winds will
increase on Wednesday with a good chance of SCA conditions on
Wednesday then likely SCA conditions on Thursday with a chance of
gale force gusts. The winds will gradually diminish into the
weekend with SCA conditions possible on Friday then no SCA
conditions on Saturday.
For the inner waters north of Point Conception... winds and seas
will remain below SCA levels through tonight. However for
Wednesday through Friday there is a good chance of SCA level winds
developing in the afternoon and evening hours. For the inner
waters south of Point Conception... winds and seas will remain
below SCA levels through Wednesday. Winds will increase on
Thursday with a good chance of SCA level winds on Friday in Santa
Ana wind prone locations. Winds will gradually diminish on Saturday.
&&
.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.
&&
$$
PUBLIC...CK
AVIATION...RAT
MARINE...KJ
SYNOPSIS...Seto
weather.gov/losangeles
Area Forecast Discussion
National Weather Service Marquette MI
719 AM EDT TUE SEP 20 2016
.SHORT TERM...(Today and tonight)
Issued at 525 AM EDT TUE SEP 20 2016
WV imagery and RAP analysis indicated a mainly zonal pattern across
the northern CONUS/Southern Canada with a 130 knot 250-300 mb
jet from the Northern Rockies into the Upper Great Lakes. A
shortwave upstream was producing a cluster of storms over the ND/SD
border along MUCAPE gradient approaching 1000 j/kg, steep mid-lvl
lapse rates and at nose of fairly strong 850 mb moisture transport.
Over the Upper Great Lakes broad sfc high pressure has resulted in
generally cloud-free skies early this morning. Early morning temps
have fallen into the 40s over the interior west half and into the
50s east half and along the Great Lakes shores.
Today, a dry airmass will prevail with sfc ridging in place over the
region. Under mostly sunny skies through most of the day temps will
remain above normal with forecast soundings supporting highs in the
mid 70s and perhaps even higher in a few spots. Mid and high clouds
will gradually spread into the area from the west during the afternoon
with a waa pattern developing in advance of a trough over the plains.
Tonight, Waa continues tonight with a northward push of 850 mb warm
frontal boundary into Northern Wi and expect clouds to increase into
Upper Mi. Models suggest convection could initiate along warm frontal
boundary over Nrn Wi with hint of a weak shortwave moving through the
area. Will include some slight chc pops for showers late tonight far
south central in case convection over Northern Wi brushes Wi Border
counties.
.LONG TERM...(Wednesday through Monday)
Issued at 432 AM EDT TUE SEP 20 2016
An increasingly amplified pattern will be developing across N
America for the remainder of this week. Ridge/positive height
anomaly currently moving across the Gulf of Alaska will strengthen
as it shifts across the Northwest Territories to Nunavut by the end
of the week. The magnitude of the positive height anomaly at 500mb
will reach 3 standard deviations above the long term late Sept avg.
To the s of this anomaly, a trof will amplify over the western CONUS
this week. Ahead of this developing western trof, shortwave energy
in the vcnty of southern CA will be kicked ne, reaching the western
Great Lakes Wed evening. This energy will bring the next opportunity
of widespread pcpn Wed into Thu. What happens late week and thru the
weekend continues to be uncertain. One aspect that has generally
been favored in the last day or so is for increased se Canada
troffing late week, which seems reasonable based on the strength of
the north central Canada positive height anomaly and based on this
anomaly linking up with the ridging farther s ahead of the western
CONUS trof. This argues for a drier period late week as sfc high
pres associated with the sharp ridge builds se into northern Ontario
and the Upper Great Lakes. Until that happens, right entrance of the
upper jet associated with the se Canada trof may continue to support
some shra into Fri. Over the weekend into early next week, attention
turns to the fate of the western CONUS trof. As CMC/GFS ensembles
and some operational medium range models began to show a day or so
ago, guidance is overall converging toward the solution of dropping
much of the energy in the western trof into the sw CONUS. Building
heights to the n of this feature will weaken/shift the mid continent
ridge e as a shortwave is forced se into the Upper Lakes late
Sun/Mon downstream of the building heights over the w. This will
provide the next good chc of shra. As for temps, after the recent
warmth, readings will be trending back to normal or a little blo
normal this week as fcst area ends up under low-level ne to e winds
btwn frontal boundary to the s and high pres building toward
northern Ontario. Coolest conditions may end up occurring early next
week behind the shortwave pushing thru the area late Sun/Mon.
Wed-Fri...shortwave energy lifting ne from the sw states ahead of
the deepening western CONUS trof will result in sfc frontal boundary
settting up from the Plains across the Great Lakes with weak low
pres waves rippling along it. Combination of shortwave energy, upper
divergence from right entrance of 120kt upper jet across northern
Ontario into Quebec, frontal boundary and precipitable water
increasing to around 1.25 inches will support pcpn development
across the Upper Mississippi Valley and Upper Great Lakes Wed into
Thu. Given avbl moisture, mdt/hvy rainfall is a possibility. Better
chc of the heavy rainfall will be s of the fcst area in WI, closer
to frontal boundary, but southern Upper MI could certainly see some
heavier rainfall at times. While 00z guidance has mostly trended
slower to push pcpn s of the area Thu into Fri, fcst will maintain
closer continuity to previous fcst in trending drier later Thu into
Fri. Pops will drop to low chc across the s into Fri while the n
trends to dry weather. Proximity of the right entrance of 120kt
upper jet leads to low confidence for the drying trend, but
eventually, sharp ridge thru central N America will support sfc high
pres building into the Upper Great Lakes, pushing pcpn s and w of
the fcst area.
Heading into Sat, the ECMWF is most aggressive with right entrance
of upper jet aiding renewed pcpn development back into Upper MI. For
now, confined chc pops to western Upper MI, in better aggreement
with the GFS/CMC.
Models show poor continuity in timing of the shortwave that reaches
the Upper Lakes early next week. Due to the inconsistencies, a
consensus of recent runs was utilized, resulting in chc pops
spreading across the area Sun/Sun night and lingering over the e on
Mon.
&&
.AVIATION...(For the 12Z TAFS through 12Z Wednesday morning)
Issued at 717 AM EDT TUE SEP 20 2016
Expect VFR conditions at all taf sites through the period. West winds
will gust into 20-25 knot range by late Tue morning into late
afternoon, strongest over the more exposed CMX site. Expect
increasing mid clouds from the west late in the day. &&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 525 AM EDT TUE SEP 20 2016
West southwest winds to 25 knots will diminish to 20 knots or less
tonight into Wed as the pres gradient weakens with the Canadian low
lifting farther ne across Hudson Bay. Winds will remain blo 20 kts
into Saturday under a weak pres gradient across the Upper Lakes.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Beach Hazards Statement until 2 PM EDT this afternoon for MIZ006.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...Rolfson
AVIATION...Voss
MARINE...Voss
Area Forecast Discussion
National Weather Service Blacksburg VA
1005 AM EDT Tue Sep 20 2016
.SYNOPSIS...
An upper low combined with the remnants of former Tropical Storm
Julia will meander about eastern North Carolina and South Carolina
through late week before finally shifting out into the Atlantic
ocean. This will keep fairly unsettled conditions east of the Blue
Ridge over the next several days, less so in western areas. High
pressure will gradually build in from the west during the later
half of the week before a cold front approaches late in the
weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 730 AM EDT Tuesday...
Removed expired dense fog advisory from products. Lower PoP chances
across the piedmont until later this afternoon. Current showers
enter an area of subsidence and relatively dry air. No other
changes at this time.
As of 330 AM EDT Tuesday...
A fairly complicated forecast through this period as a weak upper
low cuts off across the Carolinas. This upper low is combined from
the remnants of former T.S. Julia and an upper trough that cutoff
from the westerlies yesterday. Models continue to offer several
solutions as to how far west and north tropical moisture from
these combined systems will track back into the RNK CWA. The GFS
tends to be fairly dry keeping the associated rainfall closer to
the coast, while the NAM/Canadian/ECMWF spread the moisture much
further back west and north, all the way to the Blue Ridge. ECMWF
QPF is excessive, while the GFS is minimal at best. The concern,
however, is that the ECMWF, NAM, and Canadian are more similar in
QPF amounts, namely several inches as compared to the GFS. Having
said this, all models are in good agreement that more appreciable
rain will not spread back into the CWA until later today or this
evening. The HRRR and NCEP WRF models show little to no
precipitation making it any further west than the eastern parts of
the Piedmont today/this afternoon. Mid-level air spreading east
from the TN/OH valley is quite dry with mean RH less than 15%.
Therefore, in agreement with other offices, have decreased pops
for today/this afternoon, then increased into the high chance
range along RAH border after 00Z when a weak spiral band is
evident moving west into the region.
As always with this type of pattern of high tropical PWAT air
yielding an efficient warm rain process and enhanced upslope
easterly flow developing, there are concerns of enhanced, heavy
rainfall along the east slopes of the Blue Ridge. This will
certainly need to be watched over the next few days.
While we are almost a year to the date of a very heavy
rain/flooding event that evolved along the Blue Ridge in 2015,
the synoptic pattern this week is not similar. Several features in
place during the event last year are lacking at this time. We
lack a T.D. moving north out of the Gulf with PWATS in excess of
2.0 inches, an upper trough to the west, a stationary front over
the region, and strong easterly flow to the east of the front
thanks to a strong surface high over New England. So, at this
point, concerns are far less than at this time last year for such
type of event. Nonetheless, as noted above, we will need to keep a
close eye as the ECMWF/NAM/Canadian depict several inches of
rainfall across eastern NC very close to the RNK border and we are
dealing with remnants of a tropical storm, always problematic. The
key take away here is that confidence is low that the deep
tropical moisture from remnant Julia will ever make it this far
west. It is more likely to stay across the coastal plain in
association with the coastal trough.
As has been the case for weeks, no appreciable change in 850mb
temps noted through the forecast period. Temperatures will largely
be dependent on cloud cover today, less in the west, more in the
east. This will most likely yield max temps in the upper 70s to
lower 80s with lows in the upper 50s to mid 60s. These
temperatures are 5-10 degrees above normal, especially min
temperatures.
&&
.SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/...
As of 315 AM EDT Tuesday...
During this portion of the forecast, a frontal boundary will remain
stalled from near Jacksonville, FL, northeast along the east coast
to the Outer Banks of North Carolina. A closed upper low will
meander north and south along this boundary, and be centered
somewhere near the coast of South Carolina.
Model guidance varies as to the degree to which moisture on the
northern side of this system gets advected into parts of our region.
The GFS is the driest with little if any precipitation impacting our
area. The ECMWF, NAM, and Canadian solutions all to some degree
offer solutions that have precipitation impacting roughly the
southern third of the region, with the greatest concentration
across the southeast parts of the area. WPC also has been leaning
towards this wetter scenario as noted in their QPF forecasts.
Our ongoing forecast has been been mirroring these wetter solutions,
and the one from this morning will continue likewise. The biggest
alteration will be a slight shift southeast of the northern most
extent of the slight chance probabilities. Other than that, the
general orientation of the precipitation in the forecast has been
altered very little.
By Friday into Friday night, the guidance is in fairly good
agreement that the closed low will transition into an open wave and
start to progress more out to sea. This process will allow for a
decrease in coverage across the southern sections of the area. By
late Friday night, all the precipitation is expected to be out of
the area.
Thanks to decreasing wind speeds, less cloud cover, and a moist
boundary layer, late night and early morning river and mountain
valley fog is expected, especially by Thursday night and Friday
night.
&&
.LONG TERM /SATURDAY THROUGH MONDAY/...
As of 330 PM EDT Monday...
The weak closed 500mb low opens to become absorbed in the general
west to east flow which gradually takes the clouds and rain east and
off the Atlantic coast Friday night.
Upper ridge strengthens by Saturday morning but remains undercut by
low level southeast flow Saturday ahead of a shallow backdoor front
that may slide south into the area by Sunday. This supports isolated
diurnal pops Saturday before deeper upstream moisture ahead of a
stronger Midwest cold front works east along the backdoor boundary
resulting in perhaps more widespread showers by early next week.
Leaned temperatures towards Superblend with cooler readings
especially for Sunday and Monday with moderating high
temperatures for Tuesday.
&&
.AVIATION /14Z TUESDAY THROUGH SATURDAY/...
As of 740 AM EDT Tuesday...
The combination of moist ground from Monday`s rainfall and
lingering low level moisture combined with a general light east
flow along with the lack of mid/high clouds allowed for fairly
widespread dense fog formation west of the Blue Ridge, with low
clouds advecting in from the coastal plain into the Piedmont. This
has led to IFR-LIFR ceilings and visibilities across much of the
CWA this morning. Conditions should improve fairly quickly after
mid-morning with rather dry air noted above, but with a fairly
strong low-level inversion developing given high pressure aloft
and low-level moist easterly flow, MVFR clouds may hold in through
early afternoon east of the Blue Ridge.
Weather through the TAF valid period will be driven largely by
remnants of T.S. Julia and a stalled frontal boundary along the
coast. This will result in a strengthening northeast flow and even
low end gusts across the Piedmont by afternoon. This will also
keep lower clouds in these areas as well, while areas west of the
Blue Ridge should clear out and be VFR through the afternoon.
Outer bands of light rain may creep toward Danville overnight, so
added those to the TAF after 06Z. Western areas will likely see a
repeat of the dense ground fog after 06Z Wed, although confidence
in this occurring is not as high as it was this morning.
Extended aviation discussion...
Tuesday night through Friday, outside of late night/early morning
fog/low clouds, expect mainly VFR conditions with the caveat to
this being any lingering slight chance of showers from Julia per
GFS/ECMWF, mainly affecting areas east of the Blue Ridge.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...RAB
NEAR TERM...AMS/RAB/RCS
SHORT TERM...KK
LONG TERM...KK
AVIATION...AMS/DS/MBS/RAB
Area Forecast Discussion
National Weather Service Las Vegas NV
306 AM PDT TUE SEP 20 2016
.SYNOPSIS...Showers with a few embedded thunderstorms are expected
today primarily south of I-15. A strong low pressure system will
drop into the Great Basin by Thursday resulting in strong winds and
unsettled weather for much of the region.
&&
.DISCUSSION...
Moisture from tropical cyclone Paine quickly spread across the area
yesterday and at 2 AM this morning still abundant east of a line
stretching from San Diego to Elko, NV. The western portions of the
forecast area have cleared early this morning with mostly clear
conditions over Inyo and central/southern Nye counties. At 2 AM,
Radar returns were showing light to embedded moderate showers over
southeastern San Bernardino and southern/central Mohave counties.
The latest HRRR QPF forecast has showers continuing in these same
general areas through the morning hours then spreading over much of
San Bernardino into southern Clark counties this afternoon. Looking
at the various high and low resolution model QPF forecast for today
leaves most of Inyo, Esmeralda, central/southern Nye and Lincoln
counties dry as they lie north of the moisture. Clark County is
questionable but showers are not out of the question with increasing
moisture and a weak disturbance passing across the area. Models
continue to forecast relatively stable conditions today with cloud
cover limiting daytime heating. Went ahead and left in slight
chances for thunder but expect mainly showers. The greatest
potential areas for higher precipitation totals include southeast
San Bernardino and southern Mohave counties. The temperature
forecast for today is tricky based on where the deeper moisture sets
up but leaned heavily towards the MAV and ECS`s lower numbers since
there should be plenty of cloud cover around.
Wednesday becomes somewhat of a transition day with southwest flow
aloft ahead of a developing Pacific trough. Models still forecast
decent moisture left over from the departing remnants of tropical
cyclone Paine with a little better instability over the northern CWA
where the upper level support is improving and in northern Mohave
County. Southerly winds 10-20 mph are expected both Tuesday and
Wednesday.
A potent Pacific low and associated cold front will push through
Thursday and Thursday night spreading much drier air across the
region behind the front. Decent moisture remains over Mohave and
eastern Lincoln counties earlier in the day where showers and
thunderstorms will be possible then dry conditions overtake the
entire CWA in the afternoon. However, showers will remain possible
in the afternoon/evening...primarily in the eastern CWA. The bigger
story for Thursday is the wind associated with the upper low, both
ahead and behind the front. Model guidance shows a strong southwest
wind belt across San Bernardino, Clark, Lincoln and Mohave counties
with north winds pushing south through Inyo, Esmeralda and
central/southern Nye counties in the afternoon and eventually
through the remainder of the area Thursday night. There is a good
chance wind advisories will be needed for various areas on Thursday.
Decided not to issue any hazard products with this package since our
high resolution output does not go out far enough. The dayshifters
will have to reevaluate when the new hi-res model guidance becomes
available.
The low is a slow mover and models keep it in the vicinity through
the long term however with less impact to sensible weather within
the forecast area. The primary impact beyond Thursday will be
continued below normal temperatures although they will modify as
each day passes.
&&
.AVIATION...For McCarran...Messy forecast today. Dust cloud early
this morning was causing slightly reduced visibility but not likely
to persist past sunrise. Radar echoes were remaining well southeast
of the terminal early this morning, and the best chance of precip
and lower ceilings at the terminal is likely to be from this evening
into early Wednesday morning. Strong southwest winds are likely on
Thursday, with precip chances remaining east of the terminal.
For the rest of southern Nevada...northwest Arizona...and southeast
California...The best chances for rain, low ceilings, and mountain
obscuration today will be southeast of Interstate 15. After a brief
dry period for most of the area tonight, there will be thunderstorm
chances for much of the area Wednesday and Wednesday night, with
only the lower elevations of Death Valley and northern San
Bernardino County most favored to remain dry. Breezy south winds can
be expected today and Wednesday, then strong southwest winds kick up
over the Mojave Desert on Thursday ahead of a cold front, with
increasing northwest winds over the southern Great Basin behind the
front.
&&
.FIRE WEATHER... A series of systems will move through the area this
week bringing increasing chances for precipitation to much of the
area. However, as a potent Pacific trough moves through the region,
strong winds will develop across the Mojave Desert and the southern
Great Basin in advance of a cold front moving southeastward through
Nevada Thursday afternoon. Sustained winds 25-35 mph with gusts 40-
50 mph are likely in much of the region, especially in San
Bernardino County. This will be accompanied by rapid drying of the
near-surface layer, with RH`s lowering to 5-15% in these areas.
Critical fire weather conditions are expected in much of southeast
California and southern Nevada Thursday afternoon. Fire weather
watches will likely be required as the event approaches.
&&
.SPOTTER INFORMATION STATEMENT...No significant weather is expected
today. Some showers and thunderstorms are possible Tuesday through
Thursday with tonight and Tuesday currently looking like the best
chance. Spotters are encouraged to report according to standard
operating procedures.
&&
$$
Discussion...Salmen
Aviation...Morgan
For more forecast information...see us on our webpage:
http://weather.gov/lasvegas or follow us on Facebook and Twitter
Area Forecast Discussion
National Weather Service Denver/Boulder CO
257 PM MDT TUE SEP 20 2016
.SHORT TERM...(This evening through Wednesday)
Issued at 257 PM MDT Tue Sep 20 2016
For the remainder of today it will unseasonably warm and will
remain dry area-wide other than an isolated storm or two for the
Central Colorado Rockies. This evening and tonight the remnants
of Tropical Storm Paine off the coast of Mexico will phase with a
cut off low off the coast of southern California. Zonal flow at
500 mb exists across the northern Rockies, while the 500 mb ridge
is centered over Oklahoma. The result for Colorado is SW mid and
upper level flow across Colorado with considerable upper level
moisture continuing through the short term. The moisture from the
is advected for the next 36 hours and should keep us mostly
cloudy. A subtle short wave trough crosses Colorado before sunrise
Wednesday and both the NAM and the HRRR initiate light
precipitation in the mountains and sustains the showers across
the Denver metro area. It`s still quite dry in the low levels so
have low confidence in rain reaching the ground, but have seen
enough in the high res model signal to raise PoPs after 3 AM local
time to slight chance for the metro area. Minimum temperatures
tonight will stay in the low 60s across the Denver metro area and
eastern Plains, and in the 40s in the mountains given the warm
temperatures this afternoon and expected cloud cover tonight.
Throughout the day on Wednesday, a deep/strong trough will dig
south along the Pacific Northwest coast. This will continue to
advect upper level moisture across Colorado keeping the area
mostly cloudy. The low-levels will continue to be dry with surface
dewpoints will be in the lower and mid 40s across the Plains, 30s
in the mountains. Once again the best chance for afternoon
thunderstorms will be over the central Colorado Rockies. In terms
of temperatures, the warm overnight lows coupled with the dry low-
level air means temperatures should still have little trouble
getting into the mid 80s east of the mountains despite the mid and
high cloud cover. However, the cloud deck should be thicker than
today as so temperatures will be a few degrees cooler than
Tuesday, but still well above average for this time of year.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 257 PM MDT Tue Sep 20 2016
For Wednesday evening, could see just a couple showers and an
isolated storm drift northeast across the mountains, but overall
the airmass will be too stable and subsident to support much
precipitation. Lower elevations should remain dry. Temperatures
will stay quite mild but a cold front is expected to push into
the northeast plains toward Thursday morning.
This front may usher in some stratus across the northeast plains
and lead to some cooling especially on the northeastern plains for
Thursday. The airmass will destabilize in the afternoon but
mainly over the mountains as the boundary layer cools slightly on
the plains. Could still see a couple storms drift off the higher
terrain or develop on the plains toward late in the day if slight
cooling aloft occurs ahead of the deep upper level low dropping
into the Great Basin.
It appears the best chance of precipitation may occur Friday as
the upper level low approaches from the west. Right now, all
medium range models are pointing to a piece of energy rotating out
of this low and across the forecast area. This along with cooling
aloft should effectively destabilize the atmosphere so will have
the best PoPs then. Winds are also expected to increase from the
mountains eastward across the Palmer Divide and most of the plains
with strong southerly flow and pressure gradient in place.
Temperatures expected to get cold enough in the mountains for some
snow potential but appears we`ll be getting into the dry slot so
threat for much accumulation appears quite limited into Friday
night.
By Saturday, the upper level trough will begin to fill and
gradually shear. We will still be under the cold pool aloft so
will continue to keep a chance of showers and a few storms in the
forecast. Temperatures will turn considerably cooler with highs
mostly in the 60s on the plains and 40s/lower 50s in the
mountains.
The cooler weather will remain in place through Sunday, Monday,
and Tuesday as the trough weakens and/or shears southward into the
Desert Southwest. The chance of precipitation will likely decrease
through this period.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 257 PM MDT Tue Sep 20 2016
VFR conditions with mid/high level clouds this afternoon,
overnight, and through tomorrow morning. Winds should remain light
and follow diurnal patterns through 18Z. No significant weather
impacts expected.
&&
.BOU Watches/Warnings/Advisories...
None.
&&
$$
SHORT TERM...Schlatter
LONG TERM...Barjenbruch
AVIATION...Schlatter
Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
319 PM MDT TUE SEP 20 2016
.SYNOPSIS...
Higher level moisture from Tropical Storm Paine is streaming over
the area and should lead to isolated thunderstorms later this
evening, mostly west of Deming. As additional moisture moves in on
Wednesday, thunderstorms will spread to all areas. A few storms
may produce heavy rain and local flooding. The remains of Paine
will sweep across New Mexico Thursday, likely ending most
thunderstorm activity. Drier southwest flow then moves in to keep
most of the weekend dry. By Sunday night and Monday, moist low
level southeast flow combined with a developing upper low over New
Mexico and Arizona will bring a chance of thunderstorms back to
the area. Temperatures will remain above normal through Saturday,
before falling to below normal Sunday into next week as clouds
increase.
&&
.DISCUSSION...
WV imagery showing TS Paine now over the central Baja. Moisture
from the system has helped spread clouds over most of Arizona and
much of western New Mexico. Visible imagery showing considerable
orographic CU development but high aloft capping most vertical
growth. More substantial vertical growth seen over the NM
Bootheel where instability is greater and capping weaker. Radar
showing only few light showers at most over Arizona. HRRR showing
some convection developing western zones next 1-2 hours but
remaining mostly from Deming west. Expect Wednesday to be better
day for thunderstorms as Paine moisture gets closer and upper high
weakens some. Models still showing PW`s up to 1.3 inches, so can`t
rule out a few storms with heavy rain and flash flood potential.
The remains of Paine`s upper support sweep across New Mexico on
Thursday. Thunderstorms should taper off and end with this
passage.
Next Pacific trough settles in over the Great Basin Thursday with
a closed low over Utah. this will establish a drier southwest flow
over the CWA as the low drifts slowly east. Additional tropical
moisture does begin entraining into this southwest flow, but for
the weekend, remains east of us for most of the weekend.
By Sunday night, as the upper low settles in over SE Arizona, a
nice east surge at low levels develops and begins drawing the
tropical moisture west over much of the CWA. Monday/Tuesday
forecast depends on which model solution pans out. GFS continues
to retrograde the low back to western Arizona, giving much of our
area a chance of thunderstorms and moderate/heavy rainfall. PW`s
increase back to near 1.3 inches Monday but only over far west
Texas. Can`t rule out some flash flood potential there. GFS
solution shows low lifting up to four corners Tuesday night,
effectively ending the showers. Unfortunately ECMWF is showing a
different solution with this morning`s run as opposed to
yesterday`s run. Now the ECMWF is closing off the low over New
Mexico, effectively keeping the bulk of moisture east of the CWA,
though some wrap around moisture still possible. For now went with
GFS solution to avoid see-sawing, but will continue to watch for
any deviations in models. I should add that temperatures will vary
greatly depending on which model is right. GFS would suggest highs
only around 70 across the lowlands.
&&
.AVIATION...Valid 21/00Z-22/00Z...
P6SM SCT-BKN080-100 BKN150-200 through pd. Isold lowland and
scattered mtn 3-5SM TSRA BKN040-060 possible mainly through 04Z and
after 18z...but some storms possible thru pd. Winds mainly S to SE
AOB 12kts except more W to NW west of divide between 00Z and 15Z.
&&
.FIRE WEATHER...
Moisture has started to increase across the region with some Gulf
moisture as winds have become more east to southeast. Some residual
moisture from a tropical system in the Pacific will bring a chance
for some showers and thunderstorms to mainly areas west of Rio
Grande next couple of days. An upper low will be moving out of the
northwest and provide some lift across the Borderland for continued
isolated showers and thunderstorms through Thursday. Relative
humidities will remain above 20percent through at least Thursday.
Generally dry and breezy conditions for Friday and Saturday with
another moisture surge possible for early next week and cooler
temperatures.
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso 71 92 70 94 / 10 30 30 20
Sierra Blanca 66 89 64 90 / 0 20 0 0
Las Cruces 66 90 65 90 / 20 30 30 20
Alamogordo 68 90 67 92 / 10 30 30 20
Cloudcroft 46 70 48 68 / 10 50 30 30
Truth or Consequences 65 88 64 89 / 20 30 30 30
Silver City 57 83 56 81 / 30 40 30 30
Deming 64 90 63 90 / 20 30 30 20
Lordsburg 62 89 63 89 / 30 30 20 20
West El Paso Metro 72 92 71 93 / 10 30 30 20
Dell City 66 91 65 93 / 10 20 10 0
Fort Hancock 71 93 69 95 / 10 20 10 0
Loma Linda 65 87 64 87 / 10 20 20 10
Fabens 70 93 68 95 / 10 20 20 10
Santa Teresa 69 91 68 92 / 10 30 30 20
White Sands HQ 68 89 67 90 / 10 30 30 20
Jornada Range 65 90 64 90 / 20 30 30 20
Hatch 66 90 65 90 / 20 30 30 20
Columbus 67 91 66 91 / 20 30 30 20
Orogrande 68 90 67 92 / 10 20 30 20
Mayhill 52 78 53 77 / 10 50 30 30
Mescalero 53 79 54 78 / 20 60 30 30
Timberon 51 77 52 76 / 10 40 20 30
Winston 52 81 50 79 / 30 40 30 40
Hillsboro 58 87 57 85 / 30 40 30 30
Spaceport 65 88 63 89 / 20 30 30 20
Lake Roberts 52 82 51 79 / 30 40 30 30
Hurley 57 86 56 84 / 30 30 30 30
Cliff 53 87 53 88 / 40 40 30 20
Mule Creek 50 84 49 84 / 40 30 20 20
Faywood 58 87 58 85 / 30 30 30 30
Animas 61 90 62 90 / 30 30 20 20
Hachita 62 89 61 90 / 30 30 30 20
Antelope Wells 62 87 62 87 / 30 30 30 20
Cloverdale 58 85 58 83 / 30 30 30 20
&&
.EPZ Watches/Warnings/Advisories...
NM...None.
TX...None.
&&
$$
Hefner/Grzywacz
Area Forecast Discussion
National Weather Service Wilmington NC
618 PM EDT Tue Sep 20 2016
.SYNOPSIS...
The remnants of Julia will remain across eastern North Carolina
through much of the week and this will keep the weather rather
unsettled. High pressure will build into the area by the weekend
finally bringing drier conditions. A cold front will move across
the area during Sunday bringing the first hint of Autumn early
next week.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 300 PM Tuesday...An upper low spinning around in the Carolinas
will continue to provide unsettled weather across the area through
tonight. Low clouds and spotty light showers or drizzle were
covering much of the area into this afternoon. A moist northerly
flow was wrapping around the remnant low from Julia as some drier
air aloft wraps around the back of the upper low.
Sounding data and time height sections show drier air aloft from
h70 and above which looks like it may mix down enough to produce a
few breaks in the clouds especially across inland.
This all makes for a tricky forecast as the clouds will hamper
heating and therefore instability while areas that see any sunshine
will become more unstable and should see some convective
development this aftn. The cool pool aloft will drift south over
the area helping to sharpen lapse rates and promote some
convection associated with differential heating or low level
convergence. It looks like the best upper level energy and support
will ride around the upper low and combine with best convergence
associated with sfc low to produce best chc of shwrs from N-NE to
S-SW across the area through tonight. HRRR shows pcp mainly
aligned along I-95 corridor and west with only spottier shwrs to
the east closer to the coast. With such a cool pool aloft, you can
not rule out isolated thunderstorms, but temps were struggling to
make it much past the mid 70s limiting the sfc heating needed to
steepen lapse rates.
Temps will hold in the mid 70s in most places and will not drop
too much tonight under a very moist air mass with plenty of cloud
cover.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
As of 300 PM Tuesday...The remnants of Julia or a broad area of
low pressure/trough will remain up the Carolina coast through mid
week. Initially the circulation will drift southwest as it
continues to be pulled by upper low. This will leave a moist
northerly flow across much of the area through Wed into Thurs. The
models are not in total agreement with evolution of this
low/trough but it looks like it will be pulled back westward
briefly on Wed which may produce a period of on shore flow and
possibly enhance low level convergence but also may enhance
thunderstorm activity along the coast. It will depend on the
exact location of the low, both at the surface and aloft, to
determine where the best convergence, lift and upper level support
will be, but the potential will exist with a decent cool pool
aloft. Overall, expect a good deal of clouds and showery weather
through much of the period with isolated thunderstorms possible.
&&
.LONG TERM /FRIDAY THROUGH TUESDAY/...
As of 300 PM Tuesday...Remnant mid-level circulation of Julia will
still be overhead by Friday, before finally lifting off to the NE as
high pressure builds across the area on Saturday. Friday will be
near seasonable temperatures with periods of clouds of showers, but
as subsidence develops behind the departing upper impulse, Saturday
will likely rise to above climo again with much more sunshine. This
warmth will be short-lived however, as a deep trough then digs into
the northeast driving a back door type cold front into the Carolinas
Sunday, with much cooler temperatures lasting into the beginning of
next week. Increased clouds and showers are possible Sunday into
Monday with the FROPA, but the forcing is weak and moisture is
limited to the lowest part of the column. This suggests more
clouds/drizzle into Monday than true showers, but will carry low-end
POP before drying out by Tuesday. Temps Sun-Tue will drop to more
seasonable levels, and our first taste of fall-like temperatures may
occur early next week.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
As of 00Z...Pretty ugly aviation conditions tonight through the
overnight hours with IFR conditions becoming widespread due to
stratus. Likewise visibilities will lower below two miles at times
due to drizzle. Conditions will be at their worst from 06Z-13Z, with
slowly improving conditions after 15Z. North northwest flow is
expected through Wednesday morning, becoming more easterly in the
afternoon. If we get any sun on Wednesday (which is pretty
unlikely), we could see some heavier convection in the afternoon.
EXTENDED OUTLOOK...Isolated to scattered afternoon and early
evening convection possible underneath the cutoff upper low
through Friday. MVFR/IFR morning stratus/fog possible each day
thru Sunday.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 300 PM Tuesday...Northerly winds will back a little
overnight as low pressure gets pulled southward, but overall
expect N-NW 10 to 15 kts. Winds will diminish a bit and become
more variable overnight. Seas will remain less than 3 ft.
SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As of 300 PM Tuesday...Northerly winds may become quite variable
as remnant low of Julia gets pulled southward and possibly inland
late Wed. This should produce a more on shore flow on Wed.
Overall winds and seas will be determined by the exact fate of
this remnant low/trough through mid week. A longer period up to 12
second SE swell will mix in by Wed night into Thurs.
LONG TERM /FRIDAY THROUGH SUNDAY/...
As of 300 PM Tuesday...A mostly weak gradient with N/NW winds
will persist Friday and Saturday ahead of a back door type cold
front which will sag across the waters during Sunday. Wind speeds
Fri/Sat will be light, 5-10 kts or less, before steadily
increasing behind the front to 10-15 kts from the NE during
Sunday. WHile the wind will provide little contribution to the sea
spectrum, a 3-4 sec/11 sec SE swell from Tropical Cyclone Karl will
exist both Friday and Saturday, producing seas of 2-4 ft. On
Sunday, this swell will slowly wane but a NE 5-6 sec wave will
quickly amplify, producing wave heights of 3-5 ft the latter
portion of the extended.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...JDW
NEAR TERM...RGZ
SHORT TERM...RGZ
LONG TERM...JDW
AVIATION...43 MARINE...JDW/RGZ
Area Forecast Discussion
National Weather Service Lincoln IL
239 PM CDT TUE SEP 20 2016
.SHORT TERM...(This evening through Wednesday)
ISSUED AT 239 PM CDT Tue Sep 20 2016
Weak boundary a bit tough to pick out this afternoon on surface obs,
but best estimates are that it extends from near Macomb to just
north of Danville. Cumulus field continues to expand along the
boundary to near the I-70 corridor this afternoon. No sign of any
convection yet, but SPC mesoanalysis shows CAPE`s are now in the
3000 J/kg vicinity and the cap is eroded. Latest HRRR has now
started hinting at some isolated development, and will maintain the
isolated PoP`s for this afternoon, mainly between the Illinois River
and I-70.
Main steering flow will remain to our north through Wednesday, and
overnight MCS which is progged to develop over southern Minnesota
and northern Iowa will track into Wisconsin and extreme northern
Illinois on Wednesday. Local impacts would mainly be some cirrus
blowoff across the northern CWA, but skies should again be mostly
sunny. With little air mass change going on, have bumped up highs
for tomorrow a couple degrees and mainly went around 88-89 degrees
over the entire forecast area.
&&
.LONG TERM...(Wednesday night through Tuesday)
ISSUED AT 239 PM CDT Tue Sep 20 2016
Somewhat flat ridge will remain anchored over the southern part of
the US for the last part of the week and then begin to build into
the northern Miss valley for the weekend, as an upper level trough
pushes east into the plains. This pattern will bring dry and very
warm conditions to the CWA through the rest of the week and into the
weekend. With 850 temps reaching to between +18C and +20C, expecting
highs in the mid to upper 80s through most of the forecast period.
The extended models remain different in their timing of the upper
level trough for the latter part of the weekend. The ECMWF has been
the most consistent and slowest over the last several days so will
lean toward that solution and have gone several degrees warmer than
guidance for highs for Sun and Mon. The associated frontal system
finally gets into the state Sunday night and this will be the next
real chance of precip in the area. The chance of precip will
diminish as you go east and southeast, so chance pops will be in the
northwest for Sun night/north and northwest Monday/and small area in
the northeast for Monday night. By Tue, dry weather should return to
the area.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 1210 PM CDT Tue Sep 20 2016
Diurnal cumulus on the increase at midday and may provide some
broken ceilings for a time, but these will be well into VFR range.
With a boundary roughly draped from KSPI-KCMI this afternoon, an
isolated shower or thunderstorm cannot be ruled out, but coverage
will be too sparse to include in any TAF`s at this time. As the
boundary lifts northward this evening, easterly winds will
gradually trend toward the south, and remain that way into
Wednesday morning.
&&
.ILX Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...Geelhart
LONG TERM...Auten
AVIATION...Geelhart
Area Forecast Discussion
National Weather Service Marquette MI
417 PM EDT TUE SEP 20 2016
.SHORT TERM...(This evening through Wednesday)
Issued at 414 PM EDT TUE SEP 20 2016
WV imagery and RAP analysis indicated a zonal pattern across most of
the nrn CONUS with a trough moving into the Pacific Northwest. A
weak shortwave trough and area of 800-600 mb fgen supported some
light showers or sprinkles from near KDLH into wrn Upper Michigan.
Very dry air below 700 mb will limit the extent of the pcpn with only
slight chance pops mentioned late this afternoon. Otherwise, mid
clouds were thickening over the area with a broad area of 300-310k
isentropic lift in advance of sfc low pres over South Dakota.
Tonight, expect mid clouds to linger over the region in the waa
pattern with the 850-700 baroclinic zone lingering over the area.
Shra/tsra are expected to remain south of the cwa, closer to the
850mb front and higher MUCAPE values. Otherwise, the clouds will
keep min temps mainly in the 50s.
Wednesday, pcpn chances will increase from s to n as the 850 mb
front gradually lifts to the north. Additional weak shortwaves in
the fast zonal pattern will likely also support shra/tsra
development. However, with the relatively dry low level ne flow
north of the front, the pcpn into the nrn cwa will be slow with
likely pops south and only chance pops north. With MUCAPE values
fcst into the 500-1000 J/Kg over the far south some TS will also be
possible. The thickening clouds will limit highs to the upper 60s to
lower 70s.
&&
.LONG TERM...(Wednesday night through Tuesday)
Issued at 311 PM EDT TUE SEP 20 2016
Still on track to see zonal flow aloft mid week transitioning to
more amplified flow by this weekend as sharp ridge develops over the
central Conus between upper trough over eastern Canada and trough
crossing western Conus. At the sfc, a stationary front will lift
across the Upper Great Lakes Wed night through Thu Night, then
slowly settle south on Fri. Waves of low pressure tracking along
the front will help enhance rain chances. Models have been locked on
to overall scenario with pwats upward of 1.25 inches lifting into
the stationary front and along/ahead of the waves of low pressure
and large scale lift over entire area enhanced by right entrance
region of jet over northern Ontario across Quebec and any shortwaves
that will be sliding through. Heavier rain likely sets up farther
south of Upper Michigan closer to main sfc front and where MLcapes
over 1000 j/kg are located, but some heavy rain could affect south
half of cwa as that area is on gradient of h85 theta-e. Overall
there is fair agreement from the models in this scenario, though
exact placement of heavier rain remains uncertain.
Bigger question still remains on how quickly the front slips south
of area to bring dry weather on Fri. There has been little run-to-
run consistency in all models in whether front and associated
showers will be south of Upper Michigan or still lingering over at
least southern parts of cwa. At this time, GEM is most aggressive in
hanging onto qpf while last two runs of GFS and ECMWF would point to
mostly dry conditions as large Canadian high pressure builds in from
Manitoba and northern Ontario. More differences for Sat as ECMWF
continues to indicate qpf over far west and southwest cwa. Seems
these showers are tied to shortwave/q-vector convergence and h85
frontogenesis on edge of h85 thermal ridge. Trouble is that ECMWF is
not consistent with the solution as it has been back and forth on
this the last couple days. Ribbon of higher h85 RH quite narrow even
on the ECMWF focused over northern WI into sw Upr Michigan so think
it is overdone in showing broadbrushed and light qpf across much of
Upper Michigan in the 06z-18z time frame on Sat. Temps late this
week probably end up near to blo normal in the low to mid 60s,
coolest near Lk Superior with persistent northeast winds btwn the
high pressure over northern Ontario and sfc front to the south.
High pressure builds across the Great Lakes Sat and Sat night. Given
such an amplified pattern aloft, the sfc high may not move out of at
least eastern half of Upper Michigan until later Sun or Sun night.
Though timing is not set, the approaching upper level trough and sfc
trough along with low-level return flow on west side of retreating
high help will bring rain back to the area. Could be dealing with
moderate to heavy rain as pwats in the return flow regime are
forecast to top out over 1.75 inches as deep moisture flows north
off the western Gulf of Mexico. There are differences in how quickly
the sfc trough and axis of higher pwat cross Upper Michigan. This is
tied to how quickly shortwave trough moves across Upper Great Lakes
and what extent of shortwave energy is left out across the Central
Plains on Mon. Similar to late this week, run-to-run consistency on
these details in the models is lacking and agreement among the
models is also poor. Will keep using a consensus, which tilts
slightly toward quicker GFS, until these differences can be sorted
out. Though a slower solution would result in max temps Sun and
possibly Mon above normal in the 70s, will keep with consensus temps
mainly in the 60s due to the uncertainty in the timing for the
front.
Front should be east of here on Tue leaving a breezy day with some
clouds and a few light showers eventually giving way to decreasing
clouds as high pressure begins to build back in from the west.
&&
.AVIATION...(For the 18Z TAFS through 18Z Wednesday afternoon)
Issued at 137 PM EDT TUE SEP 20 2016
Expect VFR conditions at all TAF sites through the period. West
winds will gust into 20-25 knot range this afternoon, strongest over
the more exposed CMX site. Expect increasing mid clouds from the
west with the potential for a few sprinkles.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 414 PM EDT TUE SEP 20 2016
West southwest winds to 25 knots will diminish to 20 knots or less
tonight into Wed as the pres gradient weakens with the Canadian low
lifting farther ne across Hudson Bay. Winds will remain blo 20 kts
into Saturday under a weak pres gradient across the Upper Lakes.
Southerly winds will increase Sunday to 20 knots as a low pressure
trough approaches from the west.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...JLA
AVIATION...JLB
MARINE...JLB
Area Forecast Discussion
National Weather Service Las Vegas NV
220 PM PDT TUE SEP 20 2016
.SYNOPSIS...Weather will remain cool and unsettled through the end
of the week as remnant tropical moisture interacts with a trough
pushing in from the west. As the trough moves in
Thursday...increasing winds and the arrival of drier air will aid in
dangerous fire conditions for some areas along with strong
Thunderstorms in Northwest Arizona and eastern Nevada. Temperatures
will remain cool through Friday before returning to near normal
over the weekend.
&&
SHORT TERM...Through Tonight.
Three systems are currently affecting the southwestern U.S. The
first is the rapidly dying Tropical Cyclone (TC) Paine, with
moisture from it streaming well north of its center west of the Baja
Peninsula. The second is an upper-level low slowly moving
northeastward onto the Pacific Coast near San Diego. The third is an
elongated vorticity maximum to the northeast of this upper low
stretching from San Bernardino County northeast to southern Utah and
southwest Colorado. Much of the precipitation in our CWA today has
been associated with this elongated vort max, aided by the moist
advection from TC Paine. However, this afternoon, precipitation has
developed/increased in intensity in closer proximity to the upper
low near San Diego. A quasi-zonally oriented band of rain showers
has developed in southwest Mohave County and southern San Bernardino
County in advance of this upper low. Precipitation rates have
increased somewhat within this band. The HRRR has not handled this
band particularly well this afternoon. Only recently has it caught
onto the idea of its persistence/somewhat stronger intensity, and it
continues to waver on its evolution through this evening. The latest
run shows more convective-type showers continuing northeastward
through southern Mohave County through 00Z Wednesday before rapidly
progressing out of the area. Meanwhile, the western portion of the
band remains anchored to the San Bernardino Mountains and Coachella
Valley before rapidly progressing northeastward and diminishing
somewhat in association with the track of the upper low. This seems
to be a reasonable solution given the proximity to the two vort
maxima; however, given the variability seen with this evolution
simulation to simulation -- not overly confident of this.
PoPs were tweaked but remain consistent with this morning`s update,
in general. Think outside of a few sprinkles, the Las Vegas Valley
will probably not see rain, so kept PoPs confined to south/east of I-
15 through the night. Most of the heavier precip in Mohave County
should end by midnight with lighter showers possible thereafter.
Instability has been meager to nonexistent today, so even an
isolated lightning strike is not particularly likely. Nevertheless,
the increasing precipitation intensities this afternoon and the
stronger lift associated with the passing upper low led me to keep
slight thunder chances in through the night.
&&
LONG TERM...Wednesday through Monday.
Remnant moisture from Tropical depression Paine will remain in play
across the region on Wednesday beneath a broad southwesterly flow
aloft. Some cooling aloft and slightly greater sunshine potential
should allow for some marginal destabilization tomorrow afternoon
which will support the probability of greater thunderstorm coverage
across the region tomorrow as opposed to the more stratiform
precipitation event we are observing today. However, instability
will still not be very impressive and the greatest chance for
thunderstorms will be across the great Basin closer to the
approaching trough...and across Northwest Arizona.
On Thursday, a strong and dynamic trough will push into the Great
Basin region with the base of the trough dragging across our
forecast area. The impacts with this system will be two fold, strong
winds and fire danger will be one concern. While Heavy rain and
thunderstorm potential will be another concern. As far as wind and
fire goes, a dry slot in the lower levels and subsidence on the back
side of the trough will promote strong drying and downward momentum
transport to support widespread winds across much of the Mojave
Desert and low relative humidity values. Winds may require their own
headlines in subsequent updates but felt confident enough in the
fire danger to go out with a fire weather watch for much of San
Bernardino county and Clark County, as well as the Colorado River
for Thursday afternoon. We may see wind gusts exceeding 40 mph
across much of the same areas during this time. As usual with wind
events, blowing dust can be expected as the winds pick up during the
day Thursday.
Meanwhile....across Northwest Arizona and mainly eastern Lincoln
county, strong thunderstorms will be a possibility on the west edge
of remnant moisture and instability from Paine. Southwesterly shear
will be quite impressive with over 65kts of shear forecast at 500mb
and a fairly unidirectional profile. This would favor both strong
convection as well as training convection ahead of the trough. Some
models are suggesting the potential for fairly significant QPF
across northern Mohave county Thursday afternoon so flash flood
potential will need to be monitored as the event approaches.
Conditions will improve Friday as the trough pushes eastward and
high pressure attempts to build back in but temperatures will remain
cool...averaging 10 to 15 degrees below normal. Less confidence in
the longer range period extending from this weekend into next week
as the ECMWF builds a large ridge into the region while the GFS
retrogrades some trough energy into Arizona which would keep us
cooler with possible north winds especially down the Colorado River.
For now maintained a dry forecast with temperatures gradually
returning to near normal.
&&
.FIRE WEATHER...Strong winds and low humidity will combine forces
to create a period of critical fire weather conditions Thursday
afternoon. Fuels remain very dry especially north of I-40 which will
see little benefit from the remnant moisture of tropical depression
Paine. Fire weather watches are in effect for the San Bernardino
County deserts, much of the lower elevations of Clark County, the
lower Colorado River valley and Lake Mead NRA. Improving conditions
are expected friday as the winds relax.
&&
.AVIATION...For McCarran...Current thinking is ceilings will lower
to around 8-10 kft this evening, but chances of showers remain too
low to include in the TAF. Wind directions should range from 110-170
through early evening before veering to southerly around/after
sunset. Speeds 5-10 kts with occasional gusts to 15 kts through 03Z
before remaining below 10 kts overnight. Winds will be light and
diurnally driven tomorrow until stronger SW winds kick in by late
afternoon. A slight chance of storms tomorrow afternoon/evening.
For the rest of southern Nevada...northwest Arizona...and southeast
California...Showers and ceilings near/below 10 kft will continue
this evening for eastern San Bernardino and southern/eastern Mohave
Counties. Some ceiling improvement is expected by late tonight.
Scattered showers and mountain obscurations are possible in the
Sierra this evening. Winds look to be predominantly S/SE through
tomorrow morning, with speeds generally below 12 kts. Chances of
storms exist tomorrow afternoon, especially near higher terrain,
with stronger S/SW winds commencing by late afternoon.
&&
.SPOTTER INFORMATION STATEMENT...Shower and thunderstorm chances
continue through Thursday. Strong winds are also expected in much of
the area Thursday afternoon and evening. Spotter activation may be
required Wednesday afternoon through Thursday. &&
$$
Short Term/Aviation...Shafer
Long Term/Fire Weather...Outler
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