Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/19/16
Area Forecast Discussion
National Weather Service Wakefield VA
927 PM EDT SUN SEP 18 2016
.SYNOPSIS...
A trof of low pressure remains across the area tonight. Meanwhile,
Tropical Depression Julia will slowly move toward the North Carolina
coast late Monday. A cold front will slowly cross the region Monday
into Tuesday.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Latest MSAS showing a sfc trof across the VA/NC piedmont where sct
convection has developed over the past few hours. Even some lightning
strikes noted over the past hour. One hour pcpn rates suggest locally
heavy downpours as these track north. High res data is indicating
abundant tropical moisture riding north along this trof tonight
with the axis of heaviest moisture getting entrained with the
moisture approaching from the west with the front. All this is
leading to a much wetter forecast over the next 12-18 hours. Thus
have made some significant changes to the grids this evening.
Increased pops to categorical across the portions of the piedmont
and expanded the likely pops farther east per CAMS/HRRR trends.
Even the RAP is showing moisture pooling late tonight west of the
Ches Bay. The biggest change was to the QPF forecast where amounts
have been raised across the board both tonight and Monday. Total
QPF between 1-2 inches expected across the region. Added chc thunder
to piedmont next few hours per current trends. Added areas of fog
mainly west of the Ches Bay as well. Lows 70-75.
Addressed the potential for heavy rainfall in the HWO.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/...
Given the trends of some of the 00Z data, went ahead and adjusted
some of Mondays grids to reflect locally heavy rainfall.
PVS DSCN:
12z/ suite of modes continues to trend towards a rainier weather
picture for the region Monday aftn and night. Weak front slowly
crosses into the area through the day, with PW values gradually
ratcheting up >2" Monday morning and afternoon; owing to moisture
from TD Julia lifting north along and ahead of the boundary. Given
the orientation of the Theta-e ridge, sharpened by the approaching
upper trough, expect greatest concentration of showers across the
coastal plain, and rain chances have been kicked into likely range
Monday and Monday night. QPF similarly nudged upward toward WPC
forecast...around 1" over the coast, and on the order of one-
third to one-half inch inland. Will keep heavy rain mention out of
HWO/FCST for the time being given timing issues with models, not
to mention dry antecedent conditions. However, will need to watch
timing and orientation of mod to locally heavy shras as they move
across tomorrow aftn/night.
Cold front will be slow in reaching the coast (and pushing
offshore) Mon night through Tue. That in combination w/ remnant
TD low crawling NNE just off the coast will likely result in
lingering moisture E of I-95 to the coast into Tue afternoon, and
12/z models have actually slowed this process down a bit more.
Accordingly, have nudged pop into high chc to likely range along
the coast through Tuesday morning, gradually lowering Tuesday aftn
and night. Lows Mon night remain mild from the m60s W to ~70F at
the coast. Highs Tue from the u70s at the coast to m80s (well)
inland.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
The long term period beginning Tuesday night has a lower than normal
degree of confidence. The remnants of tropical cyclone Julia gets
caught up under the influence of an cutoff upper level low. The cold
front that passes through early in the week becomes an inverted
trough along the southeast coast. A moist easterly flow between low
pressure near the Southeast coast and weak high pressure to the
north may continue the chances for precipitation...mainly over
southern portions of our CWA into Thursday. Mainly dry weather is
indicated over northern portions through Friday. A cold front passes
through the Mid Atlantic States from the north next weekend bringing
a chance for scattered thunderstorms.
Temperatures are forecast to be above normal with highs in the low
to mid 80s Wednesday through Friday...warming to the mid to upr 80s
Saturday and cooling to around 80 on Sunday. Readings will be a few
degrees cooler over portions of the Lower Eastern Shore and along
the coastline. Low temperatures are expected to be in the 60s
through the period.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
Challenging TAF forecast given the tropical nature to the airmass.
First signs of increasing moisture already noted on the radar as a
band of shwrs continue to work their way NNW across the Piedmont
with other shwrs noted offshore ready to come onshore. Maintained
VFR conditions to start out forecast with VCSH to cover the current
activity. High res data conts to show copious amounts of moisture
overspreading the area both from the south associated with Atlantic
moisture and from the west with the approachingg trof. TSCTNS/BUFKIT
all show CIGS lowering to MVFR after 06Z with local IFR in shwrs
by 12Z at both RIC/SBY. The widespread pcpn may hold off until after
12Z across SERN TAF sites. Shwrs possible at just about any time
Mon but the best timing for a several period of pcpn appears to the
the morning hours across the piedmont shifting towards the coast
during the afternoon. Although thunder will be possible across SERN
TAF sites Mon afternoon, kept it out of fcst attm.
OUTLOOK...Pcpn may linger into Tues which will all depend on where
Julia tracks and its intensity as it approaches the NC coast. Dry
wx returns by midweek on as high pressure builds over the area.
&&
.MARINE...
Sub-sca conditions continue early this week. Latest sfc analysis
shows hi pres centered well off the New England coast with TD Julia
still south of the local waters. These two features will allow for
mainly se flow to continue tngt into Mon, with winds up to 10-15 kt,
3-4 ft seas over coastal wtrs and 1-2 ft waves over the Bay. Similar
conditions into Mon ngt/Tue with a weak frontal bndry washing out
over the area and the remnants of the weak tropical low still
centered south of the area. Next chance of sca conditions would be
late Wed/Thu as seas approach 5 ft out 20 nm, but this is somewhat
dependent on the exact track/strength of the aforementioned tropical
lo and associated easterly flow north of it.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...None.
NC...None.
VA...None.
MARINE...None.
&&
$$
SYNOPSIS...MPR
NEAR TERM...MPR
SHORT TERM...MAM/MPR
LONG TERM...LSA
AVIATION...MPR
MARINE...MAS
Area Forecast Discussion
National Weather Service Caribou ME
920 PM EDT SUN SEP 18 2016
.SYNOPSIS...
A moist southerly flow will persist across the region through
Monday. A cold front will cross the region on Tuesday with a
return to cooler weather by mid week. Even cooler weather can be
expected by late week.
&&
.NEAR TERM /THROUGH MONDAY/...
9:20 PM Update...Water vapor satellite pictures show a moist
west/southwest flow into northern New England this evening around
a strong western Atlantic ridge. The 00z KCAR sounding also
showed the flow aloft and had a precipitable H20 of 1.18 inches.
It is dry across the CWA this evening, but showers and storms
currently across central NY State are expected to spread across
the Down East region and parts of central Maine toward morning.
The thunderstorm activity is expected to diminish overnight, so
the chance of thunder will be small across our CWA, but the HRRR
does show some convection that tries to fire across northern
portions of the CWA late Monday morning. At this time, only some
minor updates planned based on the latest observations and
radar/near term model trends.
Previous discussion... High pressure will remain across the
western Atlantic tonight. A moist southwest flow around the high
will keep skies mainly cloudy overnight. Precipitation chances
will increase after midnight, especially downeast, in advance of
the next short wave approaching in the southwest flow aloft.
Temperatures tonight will once again remain on the mild side with
a moist airmass in place and abundant cloud cover. Expect lows to
only fall to around 60 degrees, with a few upper 50s possible
across far northwest Maine.
Showers will persist on Monday as the short wave crosses the
region. Some of the showers may be heavy across downeast areas
with precipitable water values in excess of an inch an a half.
In addition, some moisture from TD Julia will get entrained
northward across the area in advance of the approaching trough
enhancing the heavy rain potential. Will mention the chance for
heavy rain at times during Monday across downeast areas. High
temperatures on Monday will be close to 70 degrees across the
region.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
Short term begins with unsettled wx still lingering acrs the area
with showers slowly pulling out by midnight. Wl lkly see lingering
stratus and widespread fog with ocnl drizzle at times thru the mrng
hrs. Extensive low-lvl moisture wl cont to stream north on srly flow
ahd of next cdfnt expected to cross Tue/Tue ngt.
A cdfnt wl drop south out of Canada on Tue then crossing into NB Tue
evng. Expect just a brief pd of lkly pops in the aftn acrs the far
north as zones are closest to upr lvl frcg. Instability looks vry
meager at this point altho 12z NAM is indicating CAPEs 1000+ acrs
the north in the aftn. Hv only mentioned showers as NAM conts its
tendency of over-forecasting instability. Expect patchy fog to
linger ovr the waters in the mrng with sun breaking out acrs
Downeast zones in the aftn ahd of the bndry. This wl bring maxes
into the u70s acrs the south for all but coastal locations as they
wl rmn in onshore flow. Temps wl be able to rebound into the 70s for
the north ahd of front, 5-8 degrees abv normal.
Fairly nice day on tap for Wed with temps slightly cooler than Tue
but still abv normal. H5 flow wl be zonal through the end of the
period.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
Hipres builds in Wed night with next system mvg thru the Great Lakes
by Thur mrng. This wl spread showers into nw zones Thur evng with
showers expected acrs CWA Thur night and Fri as lopres drags a cdfnt
thru the state. With 1030mb sfc high pressure building out of Canada
for the weekend expect temps to cool down, with maxes on Sat
expected to rmn in the 50s acrs the North Woods and into the l60s
for Downeast.
&&
.AVIATION /01Z MONDAY THROUGH FRIDAY/...
NEAR TERM: VFR conditions this evening will give way to IFR later
tonight in lower clouds and patchy fog, and across the Down east
region showers toward morning. Hints of IFR already showing up at
KHUL as if 9 PM, but may only be temporary. IFR/MVFR conditions
can be expected in showers on Monday.
SHORT TERM: IFR conditions expected Mon night into Tue morning.
Conditions should improve to MVFR across the north Tue afternoon
and to VFR at southern terminals. VFR expected into Thur evening
before lowering to MVFR/IFR during the overnight as showers move
in from the west.
&&
.MARINE...
NEAR TERM: The Wind and seas should remain below small craft
advisory levels through Monday. Visibility will be reduced to 1 to
3 nm in patchy fog overnight, and 1 nm or less at times in
showers and patchy fog on Monday.
SHORT TERM: Wind and seas expected to remain below SCA criteria
through the middle of the week. Seas may approach 5 feet in
southerly swell Fri morning.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...CB/Duda
Short Term...Farrar
Long Term...Farrar
Aviation...CB/Duda/Farrar
Marine...CB/Duda/Farrar
Area Forecast Discussion
National Weather Service Grand Forks ND
955 PM CDT SUN SEP 18 2016
.UPDATE...
Issued at 948 PM CDT Sun Sep 18 2016
Convection exiting the FA, now confined to the Lake of the Woods
region. West winds have settled down with gusts ending this
early evening. Will see a clear overnight give way to some clouds
in the southern valley as showers in SE MT track along the SD/ND
border arriving around 12Z. PCPN is expected to remain on the SD
side of the border.
&&
.SHORT TERM...(This evening through Monday)
Issued at 327 PM CDT Sun Sep 18 2016
An upper wave is currently moving through ND/MB...with drying
noted in water vapor imagery across central ND. A surface trough
lies in the Red River Valley...extending south from surface low in
Manitoba. Temps have risen to 77-81 in the Cando-Devils Lake-
Langdon area where westerly winds and more sun have prevailed.
Seeing low/mid 70s across much of the RRV and upper 60s/low 70s
further east in Bemidji to Lake of the Woods country. Believe
we`ll still see some more warmth push east as the trough
progresses eastward and clouds start to diminish late this
afternoon.
Still could see a thunderstorm or two in the north...closer to the
Canadian border with the main upper wave late this afternoon and
this evening. A few older runs of the HRRR tried to bring in some
precip to the Fargo area this evening. Latest HRRR has dropped
that although 18Z NAM still has a blip. Will keep it dry that far
south for now. Clouds will diminish and a weak cold front will
pass through the area tonight. But with westerly winds...lows
should only dip to the low 50s across the area.
Monday...the large surface low will be over Hudson Bay and high
pressure will be over Nebraska...giving westerly winds to the area
under sunny skies. Temps are expected to range from the upper 60s
northeast (Lake of the Woods) to mid 70s southwest (across SE ND).
.LONG TERM...(Monday night through Sunday)
Issued at 327 PM CDT Sun Sep 18 2016
The beginning of the long term will bring the end of the quiet
weather before a fairly active period commences. Upper level zonal
flow will continue with broad high pressure in place across the
upper Midwest. Monday night will see temperatures right around
normal values as clear skies give way to clouds moving in from the
west towards morning. The ECMWF depicts an area of QPF along and
south of I-94 on Tuesday while the other models remain dry.
Therefore, continued with a dry forecast with low confidence of
anything actually occurring. Although the area could see limited
sunshine, high temperatures should be able to get up into the upper
60s across the north and maybe the mid 70s in the south.
The pattern will then transition to southwest flow aloft as a strong
upper low deepens across the Pacific Northwest. This system is
progged to makes its way towards the four corners region midweek,
then head northeast towards the Dakotas by the weekend, providing
the area numerous chances for precipitation throughout the remainder
of the period.
The first appreciable wave looks to impact mainly the southeastern
half of the forecast area on Wednesday. Models are coming into
better agreement with a brief period of upper ridging building in on
Thursday so tried to cut back PoPs a bit for this time frame. Friday
into Saturday will bring the best chance for widespread
precipitation as the upper low deepens across the northern Rockies
and propagates towards the forecast area. As the low wraps up just
north of the border, much of the area could see decreasing chances
for precipitation for the second half of the weekend as a dry slot
works northward. This will need to be watched to try and pinpoint
the best areas/timing for precipitation as the event draws nearer.
Throughout the majority of the period, especially late in the work
week and weekend, the bulk of any instability looks to be across
South Dakota and southern Minnesota. Therefore, continued with the
previous thinking of mainly rain showers, except for a few rumbles
of thunder here and there during the daytime hours.
After a fairly mild Tuesday, the rest of the period will see
slightly cooler temperatures with highs generally ranging from the
mid to upper 50s across the north and mid to upper 60s in the south.
The good news is that it should be awhile before another
frost/freeze threat across the area with lows expected to remain in
the 40s and 50s.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 630 PM CDT Sun Sep 18 2016
Winds turning to the west southwest this evening with SFC trough
passage. A few vicinity showers are possible in BJI, with
stronger convection expected to stay to the north of the DVL to
GFK to TVF this evening. VFR overnight with westerly winds gusting
25 to 30kts mid morning into the afternoon on Monday.
&&
.FGF Watches/Warnings/Advisories...
ND...None.
MN...None.
&&
$$
UPDATE...JK
SHORT TERM...Knutsvig
LONG TERM...Lee
AVIATION...JK
Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
623 PM CDT SUN SEP 18 2016
.AVIATION...
/00Z TAFs/
A weak surface low between the DFW area and Waco is resulting in
light north winds in the DFW Metroplex but light south winds at
KACT. In a few hours, the winds in the DFW area are expected to
become southerly and all sites will prevail southeast to southwest
winds through the end of period, at speeds less than 10 kts. VFR
conditions are expected through the valid TAF period with some
afternoon driven cumulus clouds between 5-7 kft and occasional
high clouds. Some hi-res guidance is suggesting isolated
convection occurring across the area Monday afternoon but with an
upper level ridge building in overhead, the potential for
convection at any of the airports is too low to mention in the
TAF.
JLDunn
&&
.SYNOPSIS...
Generally unseasonably hot and dry conditions are forecast
through a majority of the work week as high pressure settles in
across the region. Low rain chances will return on Friday with
better rain chances and cooler temperatures expected for next
weekend.
&&
.SHORT TERM (Tonight through Tuesday)...
Visible satellite imagery this afternoon revealed a mostly stable
atmosphere across North and Central TX with mostly fair weather
cumulus. The exception to this is across portions of eastern and
southern zones where afternoon CU looks a bit more robust. While
the overall potential for additional convection looks low at this
time, I`ll retain a slight chance (20%) of rain down across our
last tiers of counties in southeastern zones. Otherwise, the
remainder of the afternoon should be mostly sunny with light and
variable winds.
For tonight---The upper trough largely responsible for this
morning`s complex of storms is expected to slide southward through
the region resulting in continued large scale subsidence. This
combined with the generally clear skies and ample low level
moisture in place (especially for areas that received rainfall
this morning), should support a patchy fog potential.
Interestingly enough, the usually aggressive HRRR visibility
products only show minor reductions in visibility. As a result,
I`ll only add a mention of patchy fog for areas along the Red
River and across eastern/southeastern zones, where both SREF
reduced visibility probabilities are the highest, forecast
dewpoint depressions are the lowest and where rainfall analysis
indicates measurable precipitation over the past 24 hours.
For Monday and Tuesday---An H5 ridge should settle in across
North and Central TX nicely in the wake of the aformentioned
trough. The subsidence associated with this feature should mean
little in the way of precipitation with just a few patches of
afternoon cumulus. The subsidence will also allow temperatures to
warm around 5 to 8 degrees above normal values for this time of
year with most areas in the mid 90s. A few of the more urban areas
may even see temperatures closer to the upper 90s. With low level
moisture not being scoured out, heat index values will near the
century mark. Individuals that work outdoors should certainly
continue to remain hydrated and take breaks. Overnight low
temperatures will be mild with readings in the 70s. A few
sheltered and low lying areas, especially across northeastern
zones may fall into the upper 60s.
&&
.LONG TERM (Wednesday through Saturday)...
Wednesday and Thursday---Warm conditions are expected to continue
through the mid-week time frame as the mid-level ridge remains in
place. Low level moisture is expected to slowly increase,
especially on Thursday, with the weak southeasterly winds. As a
result, afternoon high temperatures may be tempered by a couple of
degrees. The mid-level ridge should maintain its magnitude and
will be efficient at limiting shower and thunderstorm activity.
Friday through Saturday---Big changes will take shape towards the
end of the work week and into the weekend. A potent upper trough
is expected to shift eastward out of the intermountain west and
into the central plains. The strong flow across the higher terrain
will induce lee-side cyclogenesis. In response,
southerly/southeasterly winds should intensifying late Thursday
into Friday morning. The increasing winds in the boundary layer,
coupled with moisture transport should result in continued mild
conditions. With this in mind, I`ve nudged overnight temperatures
upward above most statistical guidance for Friday morning. With
the mid-level ridge shifting off towards the east in advance of
the upper trough, it`s likely that some diurnally driven
convection will develop, especially across southeastern zones as
the sea-breeze lifts northward. With this in mind and with
agreement among most models, I`ve gone ahead and introduced some
slight chance PoPs across far southern and southeastern zones. Low
level winds should result in breezy and perhaps less oppressive
conditions as afternoon mixing occurs on Friday.
Rain chances will increase across all of North and Central TX on
Saturday as synoptic scale lift overspreads the region. The best
lift is expected to be across western and northern zones and this
is where the highest PoPs (40%) are painted. Good forcing for
ascent will continue through the day on Sunday as the high
amplitude trough slowly nudges towards the east. The ECMWF has
come into a bit better agreement with the latest GFS with regards
to the upper trough. This upper trough should help to drag a
noticeable cold front through much of the region resulting in
continued rain chances into early next week. Temperatures in the
wake of the cold front should fall closer to seasonal averages
with high temperatures in the 80s and overnight lows in the 60s
and 70s. Both the GFS and ECMWF both pinch the main upper level
low off from the stronger westerlies aloft. This could mean that
cooler weather and low rain chances linger even towards the middle
portion of next week, which will certainly be welcomed after the
extended period of above average temperatures.
24-Bain
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 76 98 76 97 73 / 5 5 5 5 0
Waco 74 98 73 96 72 / 5 10 5 5 5
Paris 72 96 71 95 69 / 5 5 0 5 0
Denton 73 97 72 96 71 / 5 5 0 5 0
McKinney 73 97 72 96 71 / 5 5 0 5 0
Dallas 77 98 77 97 74 / 5 5 5 5 0
Terrell 74 97 74 95 71 / 5 5 5 5 0
Corsicana 75 97 74 95 72 / 5 5 5 5 0
Temple 73 97 72 96 72 / 10 10 5 5 5
Mineral Wells 72 97 71 95 70 / 5 5 0 5 0
&&
.FWD Watches/Warnings/Advisories...
None.
&&
$$
82/25
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1037 PM EDT Sun Sep 18 2016
.SYNOPSIS...
An upper disturbance and weak frontal zone will cross our region
tonight and Monday. Dry high pressure and seasonable temperatures
will return for midweek, but low pressure lingering near the
Carolina coast could bring back some clouds and precipitation late
in the week.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 1030 PM...Shower activity has really diminished over the last
couple hours. The latest mesoanalysis page shows only 100-500 J/kg
of MUCAPE across most of the area. This on top of waning upper level
divergence, seems to indicate most of the precip is done for the
night. While the op models seem overdone on QPF, the HRRR continues
to trigger more showers as the upper trough approaches after
midnight. So I will keep some slight chance to chance PoPs
overnight. The highest PoPs will be in the northern NC mountains
where some westerly upslope is developing. Under mostly cloudy skies
and elevated dew points, min temps were nudged up a deg or two.
Monday, as the weak frontal zone increases its interaction with the
wind field and moisture surrounding Julia, it is expected to become
even less progressive, while showers and storms are expected to
consolidate along the boundary by Monday afternoon. However, this
may not occur until it shifts east of the forecast area.
Nevertheless, timing uncertainties are higher than normal. In fact,
everything for today has evolved more slowly than model guidance
earlier suggested, and it stands to reason that this trend will
continues, esp as Julia starts figuring into the equation. Monday
pops will therefore range from slight chances near the Blue Ridge,
to a solid 50 percent east of the I-77 corridor.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 230 PM Sunday: Guidance indicates that a mid level trof will
ripple over the CWA Monday night as the circulation associated with
TD JULIA slides east of Cape Fear, NC. Short range guidance agrees
that the mid level trof will develop into a closed low, remaining
over the region Tuesday through Wednesday. At the sfc, the pattern
through the short range should feature an inverted trof along the
Carolina coast with NE to SW ridge across the foothills. The NAM sfc
features appear stronger than the GFS and ECMWF, resulting in a much
wetter scenario across the Piedmont and foothills. I will favor a
blend of the ECMWF and GFS. I will trend the forecast cooler during
the daytime, blending the raw model temps with operational MOS. This
approach will generally yield low 80s across the NC foothills and
Piedmont to mid to upper 80s across the upper Savannah River Valley.
Light showers to isolated thunderstorms may spill over from the
east, supporting schc to low chc pops along and east of I-85 each
day. In addition, I will increase sky cover through the short range.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 210 PM Sunday. Starting Wednesday evening, a rather flat
upper ridge will be over the SE States and amplify a bit into Friday
then gradually break down next weekend as a trough crosses the
Rockies. A weak low which may be the remains of Julia is forecast
by the GFS and ECMWF to drift west over Georgia on Thursday and turn
north as it dissolves in a broad dispersion of moisture from the
Carolinas to Tennessee. A period of weak upslope flow from the SE
against our mountains can be expected as this dissipating low moves
north toward our area. The affects of this low should cool max temps
a few degrees for Thursday to near or slightly below normal. There
appears to be a drier period early Saturday after the weak low
dissipates and before the next system from the west gets closer.
The ECMWF develops a Rex Block pattern late in the weekend into the
next week with a large closed 500mb low anchored over the upper
Mississippi Valley. This pattern could potentially pump abundant
moisture into the Carolinas for a few days helping the drought
situation. However, the latest GFS has a much more progressive
pattern with the weaker closed low lifting out of the Dakotas and
moving east over Canada. Upslope southerly flow will increase late
Sunday and Sunday night as the approaching cold front gets closer
from the west. Meanwhile, some form of Tropical system Karl is
forecast to pass near Bermuda during the weekend.
Continued above normal temperatures except for the max temps on
Thursday under the weak low.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
At KCLT...the forecast timing of precip from the west is largely on
track. Perhaps, a few sprinkles will make it before 4z, so will put
a tempo in starting at 3z. There is also a band of showers
propagating westward on a seabreeze. This activity has a little more
instability to work with and is more robust than the stuff to the
west. However, even these showers have not been producing lightning
so far. Overnight, expect a lingering chance of showers, but overall
expect VFR conditions with plenty of mid and high clouds. Winds will
shift to N in the 8-10z time frame, but remain light. On Monday, the
strongest upper forcing will be crossing the area in the morning
with a passing upper trough, shifting east by peak heating in the
afternoon. So confidence is not high on how much convection will
redevelop near KCLT. For now, will keep a PROB30 for TS, but push it
back to midday to early afternoon, when overlap of instability and
forcing will be greatest.
Elsewhere...As expected, an area of generally diminishing showers is
crossing the area. Most of the activity is too light to produce MVFR
or lower restrictions. However, as the low-levels gradually moisten,
there may be patchy MVFR fog and/or stratus developing overnight.
Guidance is still ranging from VFR to IFR, and I will continue to
split the difference, and favor MVFR. The exception is at KAVL,
where moist up-valley flow is expected to produce low stratus. As
mentioned in KCLT above, with the passage of an upper trough, precip
chances will shift east.
Outlook: Much drier air and VFR conditions are expected behind the
front for Tuesday and Wednesday. An easterly flow may bring moisture
back from the Atlantic late in the week, raising the potential for
some restrictions Thursday and Friday.
Confidence Table...
02-08Z 08-14Z 14-20Z 20-00Z
KCLT High 100% High 100% High 97% High 100%
KGSP High 100% High 100% High 100% High 100%
KAVL Med 73% Med 73% High 88% High 100%
KHKY High 95% Med 69% High 98% High 100%
KGMU High 100% High 100% High 100% High 100%
KAND High 97% Med 79% Med 77% 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...ARK/DEO
NEAR TERM...ARK/JDL
SHORT TERM...NED
LONG TERM...DEO
AVIATION...ARK
Area Forecast Discussion
National Weather Service Marquette MI
721 PM EDT SUN SEP 18 2016
.SHORT TERM...(This evening through Monday)
Issued at 424 PM EDT SUN SEP 18 2016
WV imagery and RAP analysis indicated a zonal pattern through the
nrn CONUS with a 130-140 knot 250-300 mb jet from the Pacific
Northwest into the nrn plains. A shortwave trough from srn Manitoba
into North Dakota, near the nose of the jet and associated WAA
supported only -shra/sprinkles over nrn MN.
Tonight, as the upstream shrtwv approaches expect increasing pcpn
chances from wrn Lake Superior into nw portions of Upper Michigan.
Since the stronger 700-300 mb qvector conv with the shrtwv and upper
level div with the left exit of the jet remains mainly to the north,
only chance pops were mentioned. With MUCAPE values into the 500-1000
J/Kg range and increasing effective shear values to 30- 35 knots,
some stronger TS may be possible with marginally severe hail.
Monday, the front will sweep through the cwa bringing gusty winds and
drier air to the area with gusts approaching advisory criteria of
near 40 knots over the higher favored terrain of the Keweenaw. With
the stronger 700-300 mb qvector conv and 900-700 mb fgen asociated
with the shrtwv shifting into the ern cwa, some sct/isold shra/tsra
may redevelop in the afternoon, mainly from KERY eastward. Sunshine
and mixing with 850 mb temps around 12C will support max readings in
the mid to upper 70s, warmest in downslope locations.
.LONG TERM...(Monday night through Sunday)
Issued at 346 PM EDT SUN SEP 18 2016
Monday night through Tuesday night: The cold front will continue to
slide off to the east of the U.P. Monday evening. On the back side
of the front, the Upper Great Lakes region will be placed between
broad low pressure over northern Ontario and high pressure building
in form the South, over the mid Mississippi Valley. This will keep
the U.P. under slight ridging at the surface through this time
period with nearly zonal flow aloft. Drier air will be in place,
keeping conditions fairly quiet with above normal high temperatures
and near normal overnight lows. For reference, normal highs this
time of year are around the mid 60s with normal lows in the mid 40s.
Wednesday through Thursday: As the aforementioned high pressure
system slides off to the east of the Upper Great Lakes, low pressure
will begin to organize over the Central Plains by Wednesday morning.
Behind the departing high and ahead of the approaching low pressure
system, moisture transport from the Gulf will increase as is evident
by the isobars being wide open to the moisture source coupled with a
decent pressure gradient. PWAT values rise are expected to increase
to around 1.5-2.0 inches by Wednesday night, which is about twice
climatology for this time of year. In addition to the increasing
moisture, a warm front is progged to lift northward toward the U.P.
late Wednesday afternoon and then become nearly stationary over the
area Thursday. Forcing will increase as the front approaches and
shortwave passes through the region Wednesday night. Isentropic
upglide will also increase on the WAA into the region with moisture
transport vectors perpendicular to the isobars on the 295-300K
isosurface. At the same time, the U.P. will be in the right entrance
region of a fairly strong upper level jet, again pointing toward
increased divergence aloft. All of this points to an increased
potential of heavy rainfall Wednesday night. Thursday the front will
still linger nearby, but the forcing/isentropic ascent will not be
quite as strong so the heavies rainfall may diminish; however, the
chances for showers and thunderstorms will continue through the day.
Thursday night through Friday: The front will continue to linger
nearby, probably just south of the U.P. through this time period.
Overall forcing does not appear to be too strong and there aren`t
any strong shortwaves progged to slide through during this time
period, but the chances of showers will continue due to the
proximity and weak forcing near the front. Exact details will be
ironed out for the exact placement of surface/upper-level features
as this time period gets closer, but it does look messier and wet
toward the end of the work week.
Saturday and Sunday: Significant model differences are still showing
up from model to model and run to run during this time period, which
gives little confidence in the timing and placement of the better
chances of showers and thundestorms, but it does appear as if the
upcoming weekend will be unsettle at times. At this point have
continued to lean toward the consensus of the longer term models.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 721 PM EDT SUN SEP 18 2016
The approach of a cold front will bring in mid-level clouds and some
isolated shra to the western taf sites by late evening/overnight.
VCSH was mentioned at IWD and CMX to cover this. Also increasing SW
winds ahead of the front will result in LLWS overnight. Gusty west
winds are expected to develop by mid Monday morning behind the cold
front, especially at CMX where gusts above 30 knots are likely. Will
be VFR through the period at all sites.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 424 PM EDT SUN SEP 18 2016
a tightening pres gradient between high pressure area over the
Plains and low pressure tracking through northern Manitoba toward
Hudson Bay will cause SW winds to increase as high as 25 knots late
tonight and to 30 knots on Monday as shift wsw in the wake of the
cold front associated with the Canadian low. In fact, there could be
a period of gale gusts to 35 knots between Isle Royale and the
Keweenaw Peninsula late Monday morning into the afternoon hours as
west-southwest winds will become enhanced by channeling between
these features. West winds should generally diminish to 25 knots Mon
night into Tue as gradient slackens with Canadian low lifting
farther ne across Hudson Bay. Winds will diminish to less than 20
kts Wednesday into Friday under 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...KEC
AVIATION...07
MARINE...JLB
Area Forecast Discussion
National Weather Service New York NY
1110 PM EDT SUN SEP 18 2016
.SYNOPSIS...
A weak frontal system approaches overnight and then weakens over
the area through Monday. High pressure will then build in through
the middle of the week then slide offshore towards the end of the
work week. A backdoor cold front is then expected to cross the
area for the upcoming weekend.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
Main change this update was to slow onset of precipitation a few
hours consistent with latest HRRR and 00z NAM. Otherwise,
remainder of forecast appears on track.
Deep southwest flow ahead of a slow moving trough is expected,
with deep moisture noted.
Ahead of the trough, associated weak mid and upper level
vorticity, and left entrance region of 300 hPa jet, do expect
showers/tstms to increase in coverage and move in from NW to SE
overnight - with possibly another area of convection, over S
central VA at 3z...moving in from the SW over mainly Long
Island/Eastern CT late. With deep moisture in place, some of this
activity will produce heavy downpours. The question remains
timing, and coverage.
Plenty of clouds, high dew points, and south flow will result
in very warm temperatures overnight.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Surface front weakens as it stalls over western sections during
the day Monday. With continued deep moisture advection, and
sufficient lift aloft, expect numerous to occasional showers and
isolated thunderstorms through the day, with coverage possibly
diminishing late as surface and upper support weakens. Heavy
downpours remain a possibility.
Very warm temperatures along with high humidity persist through
Monday night as a tropical airmass remains in place.
Chances for showers/isolated thunder diminish somewhat Monday
night from west to east, but cannot rule out scattered
activity through much of the overnight, particularly east.
There is a moderate risk for rip currents at the ocean beaches.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
It is becoming more and more likely that the approaching frontal
boundary will stall and dissipate over the area on Tuesday, with the
forecast area drying out essentially from the top down as a new
airmass builds in.
This scenario will result in moderate humidity on Tuesday with a sea
breeze reinforcing the light southerly component flow. In additional
to any residual showers in the morning, there could be isolated
shower or thunderstorm initiation along the weak boundary into the
afternoon as some of the models suggest.
The airmass dries out on Wednesday as the low levels mix out and
humidity falls into the 30s. Deep subsidence will inhibit cumulus
development so a sunny day is forecast. The clear weather continues
through Thursday, then there will likely be an increase in high
clouds on Friday as subtropical Pacific moisture get entrained into
the jet.
Both the GFS and ECMWF are on board with a backdoor cold frontal
passage for the Friday night/Saturday time period. Moisture appears
to be limited, so the probability of precipitation was capped at 20
percent. If this front does come through, a significant cool down
would be on track for at least Sunday with 850 millibar temperatures
in the ECMWF down to 2-3 C. The GFS is warmer by about 2 degrees.
&&
.AVIATION /03Z MONDAY THROUGH FRIDAY/...
A cold front approaches from the west tonight, then weakens as it
moves into the area Monday.
Looks like showers and onset of MVFR or lower should be a few
hours slower than forecast, but still expect conditions to
deteriorate to MVFR/IFR overnight and to remain so until around
midday Monday. Conditions should improve to VFR Monday afternoon
at all except possibly KGON, with a low chance of lingering MVFR
KBDR/KISP. Locally heavy rainfall possible mainly Monday morning.
Isolated rumbles of thunder possible with any heavy rain, but
confidence is too low to reflect in TAFs at this time.
S-SSW flow at under 10 kt becoming light and variable throughout
at all but KJFK tonight. Could be a period of S-SSW flow under
10kt Monday morning, otherwise expect light and variable flow
throughout Monday into Monday evening.
.Outlook for 00Z Tuesday through Friday...
.Monday night...Becoming VFR western terminals, with a low chance
of lingering MVFR or lower at eastern terminals.
.Tuesday-Thursday night...VFR, except for very low chance MVFR
Tuesday morning at far eastern terminals.
.Friday...MVFR or lower possible in any stronger convection.
&&
.MARINE...
Made minor changes this update to reflect the latest trends in
observations and guidance. The forecast appears on track.
Persistent 3 to 4 ft seas on the ocean waters will continue due
to SE swell, but do not expect 5 footers at this time through
Monday night. If anything, wave guidance forecasts are running a
foot too high.
South flow diminishes tonight and Monday as a frontal
boundary approaches and weakens nearby.
Winds and waves will remain below small craft advisory levels
Tuesday through Friday with high pressure building into the region.
&&
.HYDROLOGY...
Significant rainfall is expected, with the bulk of the rain
expected to occur later tonight and through the day Monday.
A general 1/2 to 1 inch of rain appears likely, with potential
for swaths of 2+ inches not out of the question. The primary
threat appears to be for minor urban and poor drainage
flooding, with a localized threat for flash flooding. Flash
flooding will be dependent on where persistent heavy shower/tstm
activity resides and extent of frontal interaction with moisture
from the remnants of Julia.
Additionally...with astronomical tides running high...if heavy
rainfall rates coincide with times of high tide Monday morning and
afternoon, the urban flood threat will be exacerbated for low
lying coastal communities.
Mainly dry weather can be expected Tuesday through Saturday.
&&
.TIDES/COASTAL FLOODING...
Astronomical tide levels continue to run high. For high tide
cycles tonight and Monday, positive tidal departures of less than
a foot are needed to reach minor coastal flooding benchmarks. At
this time, it appears most locations will fall just short, but
just a minor positive departure could cause minor coastal flooding
benchmarks to be touched.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JMC/PW
NEAR TERM...JMC/Maloit/PW
SHORT TERM...PW
LONG TERM...JMC
AVIATION...Maloit
MARINE...JMC/Maloit/PW
HYDROLOGY...JMC/PW
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Norman OK
833 PM CDT SUN SEP 18 2016
.UPDATE...
Added patchy fog Monday morning for portions of Oklahoma.
&&
.DISCUSSION...
Model soundings continually show an fairly shallow, but steep
surface inversion for locations from south central Oklahoma to
northwestern Oklahoma. Additionally, watching HRRR runs through
this evening, a consistent, yet increasing signal for lowered
visibilities due to fog continue for portions of northwestern and
south central Oklahoma. Given current surface dew points in the
upper 60s low 70s, boundary layer moisture is prevalent. Expect
patchy, probably shallow, fog development spread across the
region, mainly confined to low lying areas, some may be briefly
dense, but do not anticipate any major impacts.
Kurtz
&&
.PREV DISCUSSION... /issued 610 PM CDT SUN SEP 18 2016/
AVIATION...
VFR conditions to continue through the forecast period. Some patchy
fog still not out of the question across parts of the area
overnight, but chances remain too low to mention in the tafs at this
point.
30
PREV DISCUSSION... /ISSUED 242 PM CDT SUN SEP 18 2016/
DISCUSSION...
Hot and humid weather with very little to no rainfall is the main
story over the next several days.
Tonight, mostly clear conditions are expected. With abundant low
level moisture (surface dewpoints in the 60s to near 70 from
recent rainfall in many areas) and relatively light surface winds,
fog may form late tonight into Monday morning in low lying areas
and may be locally dense. For now, did not mention thinking
coverage will be low and since abundant sunshine today has
allowed for a considerably amount of evaporation of ground
moisture from recent rainfall. Used a blend for model guidance
lows with a slight preference towards the cooler side.
Monday will be mostly sunny, hot, and humid. Capping is expected
to be too strong for any storm formation. Highs will generally be
about 10 degrees above average for this time of year. Heat indices
will rise to near or just above 100 degrees during the afternoon,
so it advised to exercise heat safety.
Monday night through Tuesday night, mostly clear and humid weather
with above average temperatures will continue.
Wednesday into Thursday, a mid/upper level disturbance will move
northeast across the central Plains and bring some increase in
mid and high level cloud cover. For now, rain chances appear to be
too low to mention. Above average temperatures will continue.
Friday through next Sunday, rain chances will increase across
Oklahoma and north Texas ahead of an approaching mid/upper
trough. Exact timing and impacts from this system remain uncertain
this far out. Above average temperatures will likely continue.
MBS
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 70 93 70 94 / 0 0 0 0
Hobart OK 69 94 69 94 / 0 0 0 0
Wichita Falls TX 71 97 71 97 / 0 0 0 0
Gage OK 63 95 67 95 / 0 0 0 0
Ponca City OK 69 94 70 95 / 0 0 0 0
Durant OK 72 96 71 95 / 0 0 0 0
&&
.OUN Watches/Warnings/Advisories...
OK...None.
TX...None.
&&
$$
04/26
Area Forecast Discussion...UPDATED
National Weather Service Blacksburg VA
1132 PM EDT Sun Sep 18 2016
.SYNOPSIS...
An upper trough and frontal system will move slowly west to east
across the region through Monday while tropical depression Julia
lingers off the South Carolina coast over the next several days.
This will bring a good chance of rain to much of the region
overnight into Monday. High pressure will then build in from the
Midwest, resulting in seasonal temperatures and a return to dry
conditions through the later half of the workweek.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 1125 PM EDT Sunday...
Sending a quick update to basically lower pops in all except the
far northern and eastern counties overnight given more scattered
nature to showers per latest regional radar loops. Appears
combination of dry air aloft and weakening of showers near the
upstream upper system will limit coverage over much of the region
overnight. Also band of deeper convection along the eastern
perimeter has tended to reduce coverage farther to the west with
best moisture convergence now in the Piedmont. HRRR runs have
been overdone with the degree of convection in all except the east
and has more widespread showers overnight which looks quite iffy.
Thus running with more chance coverage and limited thunder outside
the north and east through daybreak. Also temps have been slow to
fall given moist dewpoints and lack of much precip, so raised a
category or so east where may stay above 70 overnight.
Previous update as of 840 PM EDT Sunday...
Axis of lighter showers over the far west, just ahead of the
upper shortwave trough to the west seen via water vapor, continues
to edge very slowly east while diminishing given dry air aloft off
evening raobs. However starting to see a bit more convection
develop just ahead of this band along the residual instability
gradient from earlier. This combined with convection nearing the
southeast counties, with the residual band coming out of eastern
North Carolina associated with deeper tropical moisture, should
allow showers to become more widespread overnight. Latest HRRR
suggests best coverage to end up across the north overnight with
the wave heading across from the southwest, as well as out east
as deeper moisture transport from the southeast links into the
trailing wave axis late. Thus continued likely to high chance pops
most sections with some gradual increase in thunder possible
mainly Blue Ridge east as better lift arrives overnight. Still
appears given such dry antecedent conditions that most areas will
be able to handle heavy rain so not expecting many hydro issues at
this point. Kept temps a little below the latest LAV mos, mainly
60-68 overnight as expecting some cooling by showers despite
rather moist dewpoints at the moment.
Previous discussion as of 330 PM EDT Sunday...
Precipitation ahead of the approaching weak frontal boundary is ever
so slowly working its way into the region from the west. This trend
will continue with precipitation extending to the Blue Ridge by early
tonight. Water vapor imagery shows a deep plume of moisture associated
with the front extending back to the tropical Pacific and this
correlated well with precipitable water values around 2 inches. BUFKit
soundings also show deep moisture and a temperature profile favoring
efficient warm rain processes. This should help minimize thunder but
increase the heavy rain potential. However antecedent conditions are
quite dry and flash flood guidance is quite high so we can handle a
good amount of basin average rainfall without creating widepspread
hydro problems.
Dynamic support becomes a bit fragmented overnight before the forcing
begins to interact with the outer fringes of the circulation around
what remains of Julia off the Carolina coast. This will likely help
reinvigorate precipitation across the far eastern portion of our area
toward daybreak, but the heaviest rain is expected to remain just off
to our east later on Monday. This will result in a gradual improvement
in the west with some lingering showers along the Blue Ridge, but the
east will remain on the soggy side through Monday.
With extensive cloud cover and precipitation temperatures will remain
mild overnight with readings in the upper 60s to around 70 east of the
Ridge and in the low to mid 60s west. Highs on Monday will be in the
lower 80s east to mid/upper 70s west.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
As of 230 PM EDT Sunday...
Residual cold front should be east of the region Monday night with its
axis of deeper moisture likely linked with Julia still lingering off
the southern North Carolina coast. However still close enough per wrap
around low level flow to bring clouds and perhaps showers back into the
southeast espcly Monday evening before seeing rainfall push east late
into early Tuesday. Thus keeping some low chance pops mainly south/east
with clearing elsewhere overnight Monday.
Lots of uncertainty espcly eastern and southern sections Tuesday into
Wednesday as a piece of the 500 mb trough enters the region from the
west and stalls while starting to cut off aloft. This likely to capture
whats left of Julia over North Carolina by Tuesday night with some
solutions then trying to spin the band of deeper moisture back
southwest under the closing off upper system. Latest Euro more onboard
with this scenario but not nearly as robust as the Nam with the GFS/CMC
trending in that direction but drier. Since quite iffy in being able to
pull deeper moisture back inland espcly given decent surface high
pressure wedging in from the north, will leave things mainly dry
Tuesday afternoon through Wednesday, with more clouds far east and
clear to mainly sunny elsewhere. Overall temps upper 70s to mid 80s for
highs, and lows upper 50s to mid 60s, but likely quite humid across the
east per residual tropical moisture in place.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As of 145 PM EDT Sunday...
Return to an overall blocky regime will take place through the period
as a weak upper low detaches over the southeast states from the passing
early week 500 mb trough to the north. This feature likely to meander
north through late in the week before finally fading as strong upper
ridging extending in from the west becomes dominant across the
southeast U.S. Appears lingering tropical moisture from Julia likely to
become entangled with this system during midweek while possibly lifting
part of this deeper moisture north into southern/eastern sections later
Wednesday night into Friday as supported by several solutions. However
given uncertainty in the strength of the leftover upper system and
northerly extent of moisture will only include low pops south/east and
dry north.
Upper ridge strengthens by next weekend 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 shower chances by day7. Temps to remain
above normal, although tempered a bit in the 70s Thursday by more
clouds and again on Sunday per possible showers. Otherwise highs
mostly 80s and lows 50s to mid 60s.
&&
.AVIATION /04Z MONDAY THROUGH FRIDAY/...
As of 645 PM EDT Sunday...
Solid corridor of showers slowly working across the far western
mountains should continue to spread slowly east preceded by
isolated showers/storms heading up from the south. Expect the main
axis of showers, along with possibly some embedded thunder, to
slowly progress east through the night with conditions
deteriorating into MVFR over the mountains this evening, before
quickly dropping into IFR in spots overnight as the rain arrives.
Will be slow to see sub-VFR reach eastern locations but should
get an abrupt drop in cigs by late evening and espcly after
midnight pending how fast/if things saturate. Otherwise overall
expecting IFR/LIFR to develop around KBLF, KLWB, and KBCB
overnight with some MVFR for KLYH and KDAN but overall low
confidence in just how low cigs/vsbys will go. The showers may
fall apart a bit as they move eastward before regaining integrity
east of the Blue Ridge upon encountering better moisture transport
from the circulation around Julia off the Carolina coast. This
will yield some slow improvement west of the Blue Ridge later
Monday afternoon, while appears sub-VFR conditions will persist to
the east where heavier rainfall may linger through at least midday
Monday.
Extended aviation discussion...
Cold front will take until Monday evening to move completely east
of the TAF sites. Mainly VFR conditions are expected to return to
areas west of the Blue Ridge by late Monday, and to all areas by
Tuesday under a somewhat drier northerly trajectory. For the
remainder of the period, Tuesday through Friday, outside of late
night/early morning fog/low clouds, expect mainly VFR conditions
with the caveat to this being any lingering effects from Julia
per GFS/EC, mainly affecting areas east of the Blue Ridge.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...MBS/RAB
NEAR TERM...JH/MBS
SHORT TERM...JH
LONG TERM...JH
AVIATION...JH/MBS/RAB
Area Forecast Discussion
National Weather Service Charleston SC
359 AM EDT Mon Sep 19 2016
.SYNOPSIS...
The remnants of Tropical Depression Julie will move north and
remain offshore of the upper South Carolina coast today while
dissipating. A cold front will move south through the area
tonight and stall across northern Florida Tuesday. The front will
remain nearly stationary through mid to late week as high
pressure builds to the north.
&&
.NEAR TERM /THROUGH TODAY/...
Through Sunrise: KCLX reflectivity loops, 11-3.9 micron satellite
data from GOES-E and surface observations show the remnant low
from Tropical Depression Julia is becoming increasing stung out
with the circulation now oriented from northwest-southeast. Shower
activity in the form a loosely organized feeder band will brush
the Cape Romain and Mcclellanville areas for a few more hours as
the low center drifts farther to the north. In addition, a weak
perturbation moving across the CSRA could produce a few showers in
the Walterboro-Saint George-Summerville-Moncks Corner corridor
through sunrise. Will show some low-end pops in these areas to
account for possible very light measurable rainfall.
Today: The combination of deep layered forcing induced by
increasing DPVA ahead of the tail end of an approaching longwave
trough, PWATS surging well over 2 inches and broad upper difluence
will support the development of scattered to numerous showers/tstms
today as the remnant low of Tropical Depression Julia draws closer
to the Cape Fear region of North Carolina. The various high
resolution models are showing similar signals in keeping the
greatest concentration of convection anchored across the central
and coastal portions of Southeast South Carolina and Southeast
Georgia mid-late afternoon, likely due to contributions from a
weak afternoon sea breeze circulation that develops within the
nebulous pressure pattern left in the wake of Julia. 50-70% pops
will be depicted this afternoon with the highest gridded pops
confined to a broad corridor extending from roughly Ludowici
through Savannah and into the Beaufort and Charleston Areas. One
could certainly argue the need for categorical pops in some of
these areas given the consistency noted in the various model
guidance, but prefer to see a few more short-term model runs to
better pin down timing before doing so.
The rain could become locally heavy at times given PWATS are
approaching 150-160% of normal for 19 September, but mean
steering vectors show the potential for at least 10-15 kt of
motion. Minor flooding of low-lying and poor drainage areas is a
possibility given the potential for locally high hourly rainfall
rates, but flash flooding seems fairly unlikely attm. Highs today
will be a function on how quickly convection fires. Nudged the
previous high temperature forecast down a degree or so using a
blend of the latest RAP and SuperBlend output to try and
compensate for hourly convective timing. Highs will generally top
out in the upper 80s, but confidence on the high temperature
forecast is only moderate at best.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
Tonight: Deep convection will gradually wane with time as a cold
front drops south across southern South Carolina and into
Southeast Georgia after midnight. The front looks to reach the
Altamaha River by sunrise Tuesday. Fairly high pops will be
maintained across the coast as late afternoon convection will
take a few hours to wind down, but low-end pops will remain in
place through the night in response to the tail end of the
longwave trough cutting off as it becomes increasingly detached
from the main belt of the westerlies. Lows will drop into the
lower 70s with mid 70s at the beaches.
Tuesday through Thursday: Models remain in good agreement
developing a cut off low aloft over the Southeast Tuesday and
hovering it in place through Thursday. At the surface, a cold
front will move through our area by Tuesday morning, then stall
just offshore Tuesday afternoon. The cold front will gradually
develop into a trough where it is expected to remain just offshore
through Thursday. The combination of these two entities will lead
to unsettled weather for the entire time period. Deep moisture
characterized by PWATs exceeding 2" will be offshore Tuesday.
However, models hint that PWATs over our area will trend upwards
and closer to 2" Wednesday and Thursday, which is above normal for
this time of year. Additionally, slightly better dynamics may be
in place these two days, especially across the Charleston Tri-
county area each afternoon. The end result will be showers and
some thunderstorms. The severe threat remains low due to meager
instability.
Temperatures behind the front will be slightly cooler over our
northern areas on Tuesday, then even cooler over all of our areas
Wednesday and Thursday. Highs those two days should range from the
low to mid 80s, warmest in Southeast Georgia. Lows will range in the
upper 60s to lower 70s each night.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
An upper level low and surface trough will be moving over the
Southeast Thursday night into Friday. These two features will weaken
over the weekend as high pressure to our north tries to build into
the area. The net result will be unsettled weather for the long
term, especially in the afternoons. Temperatures should be near
normal for this time of year.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
VFR at both sites through sunrise. Extensive cirrus should
preclude fog and low-stratus development. Models are similar in
showing scattered to numerous showers and possibly a few tstms
developing across the area later this afternoon. Best coverage
through sunset looks to remain north of the I-16 corridor.
Introduced a tempo group for marginal MVFR conditions in -SHRA at
KCHS from 19-21z to cover. Confidence not as high at KSAV for
impacts, so will not introduce any mention of SHRA attm. This will
be reevaluated for the 12z TAF cycle. Instability is marginal for
tstms this afternoon, so no mention of TSRA will be included at
either site.
Extended Aviation Outlook: Brief flight restrictions are possible
resulting from showers and/or thunderstorms, mainly each
afternoon.
&&
.MARINE...
Today: Westerly winds will back to the southwest and south today
as Julie moves north and the afternoon sea breeze develops. Winds
will remain 10 kt or less with seas 1-3 ft.
Tonight: Winds will turn northwest to north as a cold front drops
south. Winds will be 10 kt or less with seas 1-2 ft.
Tuesday through Saturday: A cold front will move through the area
Tuesday morning, then stall just offshore while gradually developing
into a trough. The trough is forecasted to remain just offshore mid
week, then gradually move onshore by the end of the work week.
Unsettled weather is expected across the coastal waters during this
time period with brief periods of increased winds and seas. However,
overall wind and sea conditions should remain well below Small Craft
Advisory levels.
It`s still early, but we`re keeping an eye on Tropical Cyclone Karl
far off in the Atlantic. Depending on its eventual intensity and
movement, swell could reach our beaches in a few days and cause an
increased threat of rip currents.
&&
.TIDES/COASTAL FLOODING...
Astronomical influences and general north/northeast winds could
produce shallow salt water flooding for the next few days, mainly
along the Charleston County coast during the morning high tides.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
ST/MS
Area Forecast Discussion
National Weather Service Miami FL
435 AM EDT MON SEP 19 2016
SYNOPSIS... High pressure over the region will maintain light
flow with diurnally driven showers and thunderstorms over the next
couple of days. An increase in moisture on Tuesday and Wednesday
will lead to a slightly higher coverage of storms. Typical
summerlike weather will return on Thursday into Friday with a more
pronounced easterly flow.
.DISCUSSION...
At 4 AM EDT, doppler radar indicated some blips of light to moderate
showers around 60 miles east of Miami Beach. Otherwise, fairly
quiet conditions resided over land. The 00Z MFL sounding showed
3500 J/KG of most unstable CAPE, a slight increase compared to 24
hours ago. Light and variable winds were noted from the surface
up to around 400 mb, with stronger northeast winds aloft. The
light low level flow will allow for both the Atlantic and Gulf sea
breezes to develop during this afternoon. The small scale models,
including the HRRR and Hi- Res WRF, prog the sea breeze collision
to occur from western Miami- Dade county northward towards western
Palm Beach county. As reflected in the grids, this region should have
the highest chance of precip today. Some of these storms could
produce outflow boundaries which would act to spark new convection
over the east coast metro during the late afternoon or evening.
Waterspout potential over the coastal waters will be slightly
elevated due to the light wind profile and steeper lapse rates in
the lower levels. Otherwise, relatively warm 500 mb temps and high
freezing levels will limit the main storm hazards to frequent
cloud to ground lightning and brief wind gusts 35- 45 mph. By
tonight, with the loss of diurnal heating, greatest chances of
storms will reside over the Atlantic waters. A very similar
weather pattern will take shape on Tuesday and Wednesday, with
light flow and afternoon/evening showers and storms, mainly over
the interior.
Thursday into Friday models indicate a slight decrease in PW and the
reestablishment of deep easterly flow. This pattern should shift
afternoon convection back towards the western interior and Gulf
coast. By this weekend, flow will become light and variable with
another round of increasing moisture.
Near normal temperatures will occur this week with heat index
values mainly ranging from the upper 90s to around 100 degrees.
&&
.MARINE...
Outside of local sea breeze effects, winds will
generally be east to southeasterly at 10 knots or less over the
next few days with seas 3 feet or less. Isolated to scattered
showers and thunderstorms will be possible each day with locally
erratic winds and hazardous seas in and around thunderstorms.
&&
.AVIATION...
VFR conditions should prevail at all terminals through the late
morning hours, although some brief periods of MVFR cigs are
possible. VCTS periods with scattered thunderstorms developing
around the terminals is again anticipated this afternoon, with
possible periods of MVFR conditions under lowering cigs and
reduced vis during heavy downpours. VFR conditions should follow
during the evening hours, but there may be some lingering cells
around APF through midnight.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 90 75 91 76 / 50 40 50 50
Fort Lauderdale 91 77 90 78 / 50 40 50 40
Miami 91 77 91 78 / 40 30 50 40
Naples 89 77 90 77 / 40 20 40 20
&&
.MFL Watches/Warnings/Advisories...
FL...None.
AM...None.
GM...None.
&&
$$
DISCUSSION...27/JT
MARINE...27/JT
AVIATION...17/AR
Area Forecast Discussion
National Weather Service Marquette MI
508 AM EDT MON SEP 19 2016
.SHORT TERM...(Today and tonight)
Issued at 507 AM EDT MON SEP 19 2016
WV imagery and RAP analysis indicated a strong zonal flow pattern
across the nrn CONUS upstream of the Upper Great Lakes with a 130-
140 knot 250-300 mb jet from the Pacific Northwest into the Northern
Plains. A vigorous shortwave trough at the nose of this jet max and
associated WAA has supported showers/t-storms over western Upper Mi
and Lake Superior early this morning. Elevated instability to near
1000 j/kg even supported a few stronger storms over western Lake
Superior which warranted the issuance of a special marine warning.
Elevated instability appears to be waning a bit in a past few hours
as airmass may be drying out and becoming more capped at mid-levels
per forecast soundings. This is reflected in weakening trend in
convection over north central Upper Mi in past hour. Convection
still going over eastern Lake Superior aided by lift 850 mb warm
front, but generally showing a weakening trend as well.
Today, the cold front will sweep through the cwa this morning into
early afternoon bringing gusty winds and drier air to the area with
gusts approaching 40 mph over the higher favored terrain of the
Keweenaw as noted on 00z forecast soundings. Although models show
best q-vector convergence and deeper moisture lifting generally
north and east of Lake Superior later this morning, there is another
pocket of q-vector convergence that moves into the south central and
eastern forecast area later this morning into the early afternoon
hours assoc with a secondary weaker shortwave now over the Dakotas.
Although models show drier air at mid-lvls there are a few hundred
j/kg of MLCAPE and low-lvl convergence along frontal boundary could
maybe touch off a few showers and possibly a thunderstorms over the
scntrl and ern fcst area by early-mid afternoon so wl include lower
chc pops for this possibility. Look for drier conditions later in
the afternoon as frontal boundary pushes se of Upper Mi. Sunshine
and mixing with 850 mb temps around 12C will support max readings in
the mid to upper 70s, possibly pushing 80F for west wind downsloping
locations over scntrl Upper Mi.
Drying and clearing skies along with diminishing winds will lead to
cooler conditions tonight especially over the interior, where min
temps will lower to 45 to 50. Tighter pressure gradient and more
winds/mixing will allow min temps to stay up a bit more near Lake
Superior. Look for min temps generally in the mid to upper 50s along
the Lake Superior shore.
.LONG TERM...(Tuesday through Sunday)
Issued at 438 AM EDT MON SEP 19 2016
Fast, progressive pattern to begin the long term will give way to an
amplified pattern during this week and into next week. Amplification
will occur due to a ridge/positive height anomaly shifting into the
Gulf of Alaska/western Canada by mid week. This in turn forces a
deepening trof over the western CONUS. The magnitude of the positive
height anomaly at 500mb will increase to 3 standard deviations above
the long term late Sept avg as it shifts across the Northwest
Territories to Nunavut late this week. Underneath this strong
positive height anomaly, the western CONUS trof will slowly progress
eastward. What eventually happens with this trof is highly uncertain
as spread among operational medium range model runs and CMC/GFS
ensembles in recent days is significant. With the CMC/GFS ensembles,
compared to recent days, there are more indicating that the trof
will never reach the Great Lakes, or at least not reach the area
during the next 7 days, as the energy drops out of the main flow and
settles into the sw CONUS. Mostly gone from the ensembles is the
GFS/ECMWF indication a day or so ago of the western trof going on to
become a large mid level low over the Upper Mississippi Valley/Great
Lakes region early next week. As the western CONUS trof amplifies
Tue/Wed, it will kick energy off the southern CA coast to the ne,
reaching the western Great Lakes Wed evening. This wave will bring
the next opportunity of widespread pcpn late Wed into early Thu.
Later Thu into Fri, pcpn fcst will hinge on strength of se Canada
troffing in response to the western Canada ridge. If the trof is
stronger, the baroclinic zone/frontal boundary will be forced far
enough s to allow for a period of dry weather later this week. If
not, the front will remain near the area to continue the chc of
pcpn. Recent days model runs and ensembles overall tend to favor the
former idea. As alluded to above, what happens over the weekend and
into Mon is highly uncertain, but it would appear pcpn chances will
increase again, unless the trof is left behind over the sw CONUS. As
for temps, above normal temps over the next couple of days will
trend down to around normal or even slightly blo normal during the
last half of the week as fcst area falls under low-level ne to e
flow with sfc front to the s and high pres ridge building into
northern Ontario.
Beginning Tue, expect a dry day under rising heights and a dry air
mass. After abundant sunshine to start the day, mid to high level
moisture streaking into the area will lead to an increase in
mid/high clouds from the w during the aftn/evening. Fcst soundings
suggest highs on Tue will top out mostly in the lower to mid 70s.
Dwpts will will be down into the 40s away from lake moderation.
Winds will still be on the breezy side across the Keweenaw on Tue,
but not as strong as today as pres gradient weakens with sfc high
pres ridge closer to the area.
Trof that will be amplifying into the western CONUS Tue/Wed will
pick up energy off the southern CA coast and send it ne, reaching
the western Great Lakes Wed evening. With pwat surging up to 1.5
inches and assistance of upper divergence associated with right
entrance of upper jet across northern Ontario/Quebec, expect shra to
overspread the area Wed/Wed night. There have been subtle overall
model trends to shift pcpn shield se a bit under slightly more
influence of se Canada troffing. Pops will show a gradient from low
chc nw to likely se. Pcpn will then diminish and/or end from nw to
se on Thu. Nw portion of the fcst area is most likely to trend dry
as sfc front drifts se with passage of shortwave.
Although there have been some inconsistencies from run-to-run,
overall model trend over the last day or so is for se Canada
troffing to be stronger heading into Fri, which seems reasonable
based on the strength of the positive height anomaly moving into n
central Canada. In addition, models are now tending to link up
ridging ahead of the western CONUS trof with that strong positive
height anomaly. All of this allows stronger sfc high pres ridging to
develop toward the Upper Lakes, pushing sfc frontal boundary farther
s. So, at this point, Fri is looking to be a dry day, but will hold
onto low pops across the s until this drier scenario has better run-
to-run consistency among the medium range models.
Over the weekend into Mon, fcst uncertainty is much higher than
normal for this time range. Both the 00z operational CMC and UKMET
have solutions similar to a number of GFS/CMC ensembles in settling
the western trof into the sw CONUS which could end up leaving dry
weather to prevail here this weekend. For now, fcst will maintain
some continuity with the idea that some form of the western trof
will eventually affect the area Sat thru Mon, resulting in pcpn
chc spreading back across Upper MI.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 137 AM EDT MON SEP 19 2016
The approach of a cold front will bring in mid-level clouds and some
scattered showers/isolated tsra to the western taf sites overnight.
VCTS was mentioned at IWD and CMX to cover this. Also increasing SW
winds ahead of the front will result in LLWS overnight. Gusty west
winds are expected to develop by mid Monday morning behind the cold
front, especially at CMX where gusts near 35 knots are likely. Will
be VFR through the period at all sites.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 507 AM EDT MON SEP 19 2016
Gusty s-sw winds will shift wsw later this morning into the
afternoon hours as a cold front move across the area. The tightening
pres gradient between high pressure area over the Plains and the low
assoc with the front tracking through northern Manitoba toward
Hudson Bay will result in WSW winds to 30 knots today in the wake of
the cold front. In fact, there could be a period of gale gusts to 35
knots between Isle Royale and the Keweenaw Peninsula this afternoon
as west-southwest winds will become enhanced by channeling between
these features. West winds should generally diminish to 25 knots Mon
night into Tue as gradient slackens with the Canadian low lifting
farther ne across Hudson Bay. Winds will diminish to less than 20
kts Wednesday into Friday under weak pres gradient across the Upper
Lakes.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...Rolfson
AVIATION...07
MARINE...Voss
Area Forecast Discussion
National Weather Service Blacksburg VA
419 AM EDT Mon Sep 19 2016
.SYNOPSIS...
An upper trough and frontal system will drift slowly east across
the forecast area today, then stall across the coastal plain of
Virginia and North Carolina Tuesday. The remnants of Tropical
Storm Julia will drift west into the Carolinas and linger along
the stalled front through late week. Meanwhile, high pressure will
build across the Tennessee Valley into the Mid-Atlantic region
during the later half of the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 400 AM EDT Monday...
Long awaited frontal system drifting across the western part of
the forecast area this morning. While most of the rain that fell
Sunday averted the RNK CWA, things are looking somewhat more promising
this morning as bands of showers redevelop along/in advance of the
slow moving frontal system and in right entrance region of upper
jet stream. HRRR seems to have a good handle on the pattern, so
largely used its suggest simulated reflectivity to gage pops. This
will keep high chance to low likely pops most areas through the
mid-morning then tapering off as conditions become less favorable
for this pattern to continue as the day progresses, along with
drier air spreading into areas west of the Blue Ridge.
Complicating factor throughout the period, and especially beyond
is the movement of T.D. Julia and its interaction with the frontal
system. Models differ considerably on how this will evolve with
the ECMWF/NAM drifting Julia west into and through NC/SC and
eventually into GA, while the GFS keeps the remnants of Julia tied
with the frontal boundary stalled along the NC coastal plain,
basically depicting a coastal front that lingers for several days.
Regardless of the model, it does appear that we will be dealing
with the moisture associated with Julia for days near or perhaps
in parts of the CWA. Therefore, have held onto low chance pops
east of the Blue Ridge even beyond 00Z Tue as moisture likely
spreads back northwest from T.D. Julia and the stalled frontal
boundary. Many uncertainties to deal with here, most of which lie
just beyond this forecast period.
Temperatures today should be quite a bit cooler than observed
Sunday with extensive cloud cover all areas and greater
precipitation chances in the east. Max temperatures will still be
above normal today, but on the order of 5-7 degrees instead of
10+ as in recent days. Min temps will remain well above normal,
50s west to 60s east. Keep in mind lows should be in the 40s west
to 50s east at this time of year!
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
As of 300 AM EDT Monday...
Model guidance the past few days has been providing an array of
solutions regarding the interaction of the passing cold front and
the remnants of Julia. The solutions have included no interaction,
whereby in the wake of the cold front dry and mild conditions are
expected the remainder of the week. Solutions have also included
the remnants of Julia making slow progression westward onshore,
helping to stall the front over or near the southeastern part of
the region, all while streaming Atlantic moisture into our region
on an increasing easterly flow.
As time has progressed, more guidance, as well as, WPC, have been
leaning towards the latter over the former. While the forecast this
morning will not reflect the magnitude of precipitation into the
region as the 00Z/8PM operational ECMWF and NAM models provide, it
will start to lean toward a solution that has isolated to scattered
coverage of showers across the southern and eastern portions of the
region.
This scenario will also provide from more cloud cover and slightly
cooler than previously forecast high temperatures, especially in the
southern and eastern portions of the area.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
As of 415 AM EDT Monday...
Upper ridge strengthens by next weekend 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 shower
chances by day7. Temps to remain above normal, although tempered a
bit in the 70s Thursday by more clouds and again on Sunday per
possible showers. Otherwise highs mostly 80s and lows 50s to mid
60s.
&&
.AVIATION /08Z MONDAY THROUGH FRIDAY/...
As of 145 AM EDT Monday...
Patchy light rain showers are making their way into the southwest
portion of the forecast area. Flight conditions in this region
are mainly in the MVFR range with pockets of IFR. Elsewhere across
most of the rest of the area VFR conditions continue to prevail
with isolated coverage of showers. The trend through the remainder
of the overnight hours will be IFR/MVFR to become commonplace
across the whole region with patchy showers continue to spread to
the northeast. The heaviest showers are expected to remain near
and east of a KDAN-KFVX line. A rumble or two of thunder is also
possible in this region.
During the daytime Monday, coverage of showers will gradually
decrease from west to east, but remain at least scattered in
eastern sections through at least the early evening. Flight
categories are expected to improve to low end VFR at most
locations by 18Z/2PM. Pockets of MVFR ceilings will continue
across eastern sections.
Monday evening, lingering low level moisture and developing
inversion will allow for the redevelopment of a MVFR ceiling
across most of the region with areas of light fog. Isolated to
showers will continue east a KDAN-KLYH line.
Extended aviation discussion...
Tuesday through Friday, outside of late night/early morning
fog/low clouds, expect mainly VFR conditions with the caveat to
this being any lingering effects 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...RAB
SHORT TERM...DS
LONG TERM...JH
AVIATION...DS/JH/MBS/RAB
Area Forecast Discussion
National Weather Service Caribou ME
757 AM EDT MON SEP 19 2016
.SYNOPSIS...
A moist southerly flow will persist across the region today. A
cold front will cross the region Tuesday with a return to cooler
weather by mid week. Even cooler weather can be expected by late
week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Update...
Latest radar reflectivity shows an area of rain moving northeast
across downeast areas this morning. Latest HRRR shows rain
expanding northeast reaching southeast Aroostook by mid morning.
Adjusted pops to around 100 percent across central and downeast
per latest radar trends and meso-scale guidance. Steady rain
doesn`t appear as if it will make it into far northwest Aroostook
so will only mention scattered showers there. Have also extended
areas of fog a few more hours this morning and an SPS has also
been issued to address the locally dense fog this morning. Lastly,
adjusted QPF through this afternoon to raise amounts across
Washington County where some locally heavy rain will be possible.
previous discussion
Low pressure will pass to the north of the region today. At the
same time high pressure to the south of New England will produce a
moist return flow across the State. This will result in showers
across the region today and areas of fog tonight.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY/...
Concern this term will be the potential for convection w/the
approaching cold front on Tuesday.
A cold front is forecast to slide across the region Tuesday
afternoon w/some showers breaking out. The highest pops were
situated across the n and w(40%) while areas further s will see
isolated to no shower activity. There does appear to be some
dewpoint pooling and llvl warming ahead of a cold front on Tuesday
mainly across the far n and nw areas. Daytime temps are forecast
to hit the 70s across the CWA. Upper levels show mid level
cooling w/the boundary and 700-500mb lapse rates of 6-6.5 c/km.
The NAM is very robust w/its CAPE values of 800-1000 joules
w/0-6km shear of 30 kts. The NAM continues its trend of loading up
moisture in the llvls while the GFS is much weaker w/its CAPE
values(400-600 joules). The GFS does show the decent shear and
good mid level lapse rates as well. Some moisture does appear to
be evident into the 700mb layer on both the NAM and GFS. The SREF
shows some CAPE but is very weak. Attm, feel the NAM is overdone.
Decided to add isolated tstms across the n and w for Tuesday
afternoon and left out any enhanced wording attm. The daycrew can
assess this further today.
It looks like partial clearing Tuesday night w/a cooldown. Some
fog development is possible especially across the n and w where
precip fell. Added areas of fog for these areas. Overnight lows
expected to drop into the low and mid 50s. Wednesday looks to be a
drier day and cooler w/daytime temperatures in upper 60s to around
70 across the n and w while central and downeast are expected to
see to to mid 70s.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
As stated by the daycrew, high pres builds in Wed night into early
Thursday providing dry weather.
The frontal system is forecast to affect the region Thursday
afternoon into Friday as low pres moves out of the Great Lakes
region. This system is expected to bring showers into the northern
and western areas and then the showers will spread across the rest
of the cwA Thursday night into Friday. The ECMWF is a bit faster
than the GFS w/the arrival of the rain on Thursday but both show a
wave of low pres moving in along the front. This could enhance
rainfall. Attm, decided to stay w/40% pops and keep showers vs
rain. If this trend continues, the daycrew can make the adjustment
to go w/just rain for later Thursday into Friday.
The front is forecast to clear the CWA Friday night into Saturday
morning w/much colder temperatures expected into the weekend. It
will actually feel like Autumn w/daytime high temps forecast to
be in the upper 50s to low 60s.
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
NEAR TERM: Expect IFR/MVFR conditions today and tonight.
SHORT TERM: MVFR/IFR Tuesday morning w/fog and low cigs. This is
expected to burn off by the mid morning w/conditions going VFR. A
cold front is expected to bring some showers and possibly a tstm
for the northern terminals(n of KHUL) Tuesday afternoon w/a tempo
period of MVFR. VFR from KHUL to KBHB. MVFR/IFR Tuesday night into
Wednesday morning for mainly the northern terminals due to the
earlier showers. VFR Wednesday into Thursday morning.
&&
.MARINE...
Update 6:50 am: Have added scattered thunderstorms to outer waters
until 1300Z.
NEAR TERM: Have used the Nam12 for sustained winds. For waves:
The primary wave system today and tonight will be shorter period
swell (3-4 feet/6 seconds) generated across the Gulf of Maine
yesterday in a southwesterly flow. This will be accompanied by
inccoming southeasterly long period swell (1 foot/9 seconds). Will
use the near shore wave model to initialize wave grids. Have
lowered wave heights by 1 foot below model guidance.
SHORT TERM: No headlines expected into Thursday. Winds are
expected to be 10-15 kts w/seas around 3 ft. A swell looks like it
could set up by Friday wave heights possibly building to around 5
ft.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.
&&
$$
Near Term...Duda/Mignone
Short Term...Hewitt
Long Term...Hewitt
Aviation...Duda/Mignone/Hewitt
Marine...Duda/Mignone/Hewitt
Area Forecast Discussion
National Weather Service State College PA
1128 AM EDT MON SEP 19 2016
.SYNOPSIS...
A deep plume of moisture with its origin over the central Gulf of
Mexico will be responsible for numerous showers and isolated
thunderstorms ahead of a wave of low pressure and slow moving cold
front. The showers will gradually taper off from northwest to
southeast across the region this afternoon and evening...as the
front pushes through. A large ridge to our southwest will slow
provide above normal heights and temperatures to the region. Most
of the week will be dominated by this ridge. This should produce a
stretch of relatively dry weather with above normal and summer-
like temperatures peaking later in the week.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
The deep moisture plume has moved to our east and so has the
significant rainfall. There is a wave of showers associated with
a wave along the boundary which should bring another shot of
showers and rain from near Chambersburg north and east. Kept POPS
in southeast and showers/thunderstorms. I used the HRRR for the
texture of the rainfall.
Satellite imagery shows breaks in clouds in western/northwestern
PA. The rain and humid air is keeping low clouds in over most of
central areas and the METAR sites are slowly coming up. The lower
dew point air is seeping to the south and east at a very slow
pace.
Expect steadily but slowly improving weather west to east today.
Maybe even Harrisburg will see the sun...just before it sets
today.
No POPS in west/northwest today and slight chance very early in
central areas. Another warm day for mid-September. The Endless
Summer continues.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM TUESDAY/...
The front should sag south of our region this evening. This will
allow some drying out of dew points. But the weak flow, dew points
mainly in 50s/60s along with recent rains is an ideal prescription
for fog.
Expect areas of fog overnight and the fog and inversion will
likely contribute to a slow beginning to our sunny day on Tuesday.
Tuesday will be another unseasonably warm day. Endless Summer-II.
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
High pressure building in from the Ohio Valley will bring some
valley fog early Tuesday, followed by dry weather for the midweek.
A cold front over the north-central part of the country will run
into rising heights aloft as it slides toward the northeast
Tuesday, with showers evaporating as they approach. Well-above
normal temperatures (on the scale of 10-13F above normal) will
bring highs back into the upper 70s to mid 80s as anomalously high
upper heights (588-590dm at 5H) peak.
Heights don`t really fall back all that much heading into the
weekend as a large trough forms over the Rockies keeping the
ridge in place. Bit of a back-door cold front slides through on
Sat, though "cold" front may be an overstatement. Just a slight
chance for showers and a push of somewhat cooler air will nudge
temps back down toward seasonal norms. Latest guidance builds high
pressure into the region from the Great Lakes for late
weekend/early next week as sharp ridge builds aloft. So chances
for significant precip during this period remain quite low.
&&
.AVIATION /16Z MONDAY THROUGH FRIDAY/...
VFR conditions area moving from northwest to southeast across the
State. Just a few pockets of low clouds trapped in some valleys in
the northwest. Clouds are breaking up slowly but steadily over
western areas and this will be the trend over the next 6-12 hours.
Radar indicates a few residual showers near the Maryland border
and deeper clouds on satellite. Most locations should be mainly
VFR by 18Z today with a few valley locations holding out for MVFR
a bit later.
Should be a good evening. But the deep moisture and weak flow
should provide near ideal conditions for areas of deep and dense
fog overnight. Widespread LIFR and IFR is expected to develop a
few hour either side of about 0400 UTC.
Fog may be slow to burn off during the morning hours due to the
weak flow. But we anticipate VFR by noon over the entire region.
The coming week looks warm and dry with the potential for
overnight fog. We are well into our fog season and this year we
are particularly warm and humid making for some potentially interesting
events.
Outlook...
Tue-Fri...AM valley fog possible, otherwise, no significant
weather.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Lambert
NEAR TERM...Grumm
SHORT TERM...Grumm/Lambert
LONG TERM...Lambert/RXR
AVIATION...Grumm/Jung
Area Forecast Discussion
National Weather Service Wilmington NC
931 AM EDT Mon Sep 19 2016
.SYNOPSIS...
The remnants of Julia will remain the vicinity of southeast North
Carolina through much of this week. This will maintain unsettled
weather with periods of showers possible each day, along with
slightly above normal temperatures. High pressure will build into
the area by the weekend with drier conditions. A back door type
cold front will approach on Sunday.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 930 AM Monday...Radar loops show the center of the remnant
of Julia is approximately 50 nm south of Cape Fear and steadily
moving north. HRRR has this feature moving ashore around noon.
Biggest threat for today continues to be from localized flooding
due to torrential downpours. Area soundings show a very juicy
atmosphere with P/W values in the 2.25 inch range. Winds will not
be a problem as center of low is opening up and loosening. Even
offshore winds are now only in the 15 kt range. Previous
discussion follows:
Several nearly stationary rain cores have dumped several inches
in the last hour inland of Litchfield Beach and SW Dillon county.
Flood advisories have been issued for these areas. Pockets of
torrential rain and cell training will be the primary threats
today, leading to localized flooding in spots. Added `heavy
rainfall` wording to the gridded products. No other significant
changes and the previous discussion follows.
Julia`s remnant low center halted its landward drift about 120
miles south of Cape Fear in recent satellite/radar data, signaling
that a northward drift toward Cape Fear is imminent given the
upstream trough evident in early morning vapor movies. As this
occurs through morning, the expectation is an upswing in onshore
moving showers with embedded isolated TSTMS. Julia`s center may be
over Cape Fear around noon and by this time heating should start
to pop increasing convection over inland NE SC and SE NC. As the
low center drifts north of the area into evening, showers on
backside of the low will continue due to the soupy air mass and
localized convergence. After midnight showers should see a waning
trend. Onshore showers could produce gusts of 25-30 mph along the
NC coast today into this evening.
Balmy air mass in place with elevated dewpoints. In terms of severe
potential, low-level winds are not expected to become strong today
as the low approaches, but the intrusion of high precipitable water
content may lead to localized flooding in trained areas as convective
bands rotate off the ocean. A waterspout offshore is not out of the
question entirely. 0.50-1.00 inches of rainfall `average` north of
Cape Fear, to 0.25-0.50 elsewhere today through tonight.
Some areas will see higher totals. Maximums mainly middle 80s
today.
&&
.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
As of 3 AM Monday...Main headline this period `prospects for
heavy showers` as general low pressure remains across the area
with locally high precipitable water content. A weakness aloft in
the H5 fields will enhance potential for rain-loaded showers and
storms both afternoons. Maximums will run near to slightly below
average TUE/WED with plentiful clouds and showers in the mix.
Because of the scattered nature of coverage confidence too low for
a Flood Watch.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 300 AM Monday...Unsettled weather for much of the extended
as the remnants of post-tropical depression Julia merge with a
cold front and then stall across the area. The residual mid-level
and surface low will likely be forced to retrograde to the SW as
weak steering flow and a ridge to the north keep it from ejecting
out to the NE. While forcing is weak, moisture associated with
this feature will keep a chance for showers and isolated tstms
across the area each day into the upcoming wknd. By Saturday a
brief drying trend is expected as subsidence behind the mid-level
low should move into the area, before a back door cold front
begins to approach from the NE with a renewed chance for showers
on Sunday. Despite the unsettled conditions, 850mb temps and
1000-500mb thicknesses support temperatures remaining slightly
above climo for highs but well above climo for nocturnal mins.
Cooler temperatures may develop Sunday with the back door front.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
As of 12Z...An area of convection currently between KFLO/KLBT
extending SE to near KCRE is shifting slowly NE. This convection
should weaken this morning but will still have a potential to
result in VCTS at KLBT/KCRE through 12-14Z. LIFR/IFR at KFLO/KLBT
will lift to MVFR 12-14Z.
Periods of MVFR and showers are likely through the afternoon at all
terminals. Thunderstorms will be isolated today with IFR possible.
Confidence in any timing of this is low however, and have not
mentioned in TAFS. Expect generally VFR after 21-22Z. There in
increasing confidence of IFR stratus this evening and overnight
weak high pressure and substance, N winds, and moist low levels.
EXTENDED OUTLOOK...A slow eastward moving frontal boundary and the
remnants of Julia will keep the potential for showers and storms in
the forecast through Friday. AM fog and stratus is possible through
the period.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 930 AM Monday...Radar loops show the center of the remnant
of Julia is approximately 50 nm south of Cape Fear and steadily
moving north. HRRR has this feature moving ashore around noon. Winds
will not be a problem as center of low is opening up and
loosening. Even offshore winds are now only in the 10 to 15 kt
range, with about 10 kts at 41013. Seas remain in the 4 to 5 ft
range. Previous discussion follows:
`Exercise Caution` flags flying early this morning and today for
4-5 foot seas and occasional gusty winds in showers, as the
remnant low of Julia drifts north toward Cape Fear. Any shower
could produce gusts to 25 KT on open water today and tonight. A
radar update before venturing out is a good pre- caution. SE waves
of 4-5 feet every 7-8 seconds can be expected much of this period.
Seas will be higher in showers or isolated TSTMS. As the low
center lifts slightly north of the waters tonight, winds will turn
offshore from the NW into early Tuesday, remaining light.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 3 AM Monday...Improved marine conditions as light winds are
on tap this period along with a subsiding sea-height trend. Weak
low pressure will reside across the area, so scattered showers and
isolated TSTMS can be expected both TUE/WED. SE waves 2-4 FT every
8- 9 seconds can be expected TUE/WED, highest offshore. Light chop
only this period with minimal wind-wave contribution. Isolated
waterspouts will be possible on the waters.
LONG TERM /THURSDAY THROUGH FRIDAY/...
As of 300 AM Monday...The remnants of post tropical depression
Julia will leave an inverted trough across the waters early in the
period before high pressure expands down from the NE. This will
leave a weak gradient, with winds fluctuating from NE to SE at
around 10 kts through the period. A more firm SW flow will develop
late on Friday. This light winds and lack of significant swell will
keep seas 2-3 ft through the period, with a subtle wave shadowing
along the Brunswick and Horry county coasts creating slightly lower
wave heights.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...JDW
NEAR TERM...MJC/REK
SHORT TERM...MJC
LONG TERM...JDW
AVIATION...MRR
MARINE...MJC/REK/JDW
Area Forecast Discussion
National Weather Service Miami FL
833 AM EDT MON SEP 19 2016
.AVIATION...
With low pressure off the Carolina coast, the flow, while weak,
will try to favor a westerly direction, off the surface. However,
the sea breeze is forecast to develop along both coasts, which
will be the main driving factor of not only the wind, but also
convective development. Showers and thunderstorms are forecast to
gradually develop this morning, mainly along the coast, the
increase in coverage and push inland this afternoon. However,
there is uncertainty as to the strength of the Atlantic sea
breeze, so have kept VCTS in the TAFs for mainly the afternoon and
early evening hours.
&&
.UPDATE...
No significant changes to the forecast, other than attempting to
time convection across South Florida through the day today. The
PoPs remain largely unchanged for the 6 and 12 hour period, but
the 3 hour periods show a trend of convection closer to the
Atlantic coast early on, but pushing most of the activity inland
for the late afternoon. Have also adjusted sky cover to reflect
the mostly clear skies on satellite and in the obs this morning.
&&
.PREV DISCUSSION... /issued 435 AM EDT MON SEP 19 2016/
DISCUSSION...
At 4 AM EDT, doppler radar indicated some blips of light to moderate
showers around 60 miles east of Miami Beach. Otherwise, fairly
quiet conditions resided over land. The 00Z MFL sounding showed
3500 J/KG of most unstable CAPE, a slight increase compared to 24
hours ago. Light and variable winds were noted from the surface
up to around 400 mb, with stronger northeast winds aloft. The
light low level flow will allow for both the Atlantic and Gulf sea
breezes to develop during this afternoon. The small scale models,
including the HRRR and Hi- Res WRF, prog the sea breeze collision
to occur from western Miami- Dade county northward towards western
Palm Beach county. As reflected in the grids, this region should have
the highest chance of precip today. Some of these storms could
produce outflow boundaries which would act to spark new convection
over the east coast metro during the late afternoon or evening.
Waterspout potential over the coastal waters will be slightly
elevated due to the light wind profile and steeper lapse rates in
the lower levels. Otherwise, relatively warm 500 mb temps and high
freezing levels will limit the main storm hazards to frequent
cloud to ground lightning and brief wind gusts 35- 45 mph. By
tonight, with the loss of diurnal heating, greatest chances of
storms will reside over the Atlantic waters. A very similar
weather pattern will take shape on Tuesday and Wednesday, with
light flow and afternoon/evening showers and storms, mainly over
the interior.
Thursday into Friday models indicate a slight decrease in PW and the
reestablishment of deep easterly flow. This pattern should shift
afternoon convection back towards the western interior and Gulf
coast. By this weekend, flow will become light and variable with
another round of increasing moisture.
Near normal temperatures will occur this week with heat index
values mainly ranging from the upper 90s to around 100 degrees.
MARINE...
Outside of local sea breeze effects, winds will
generally be east to southeasterly at 10 knots or less over the
next few days with seas 3 feet or less. Isolated to scattered
showers and thunderstorms will be possible each day with locally
erratic winds and hazardous seas in and around thunderstorms.
AVIATION...
VFR conditions should prevail at all terminals through the late
morning hours, although some brief periods of MVFR cigs are
possible. VCTS periods with scattered thunderstorms developing
around the terminals is again anticipated this afternoon, with
possible periods of MVFR conditions under lowering cigs and
reduced vis during heavy downpours. VFR conditions should follow
during the evening hours, but there may be some lingering cells
around APF through midnight.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 90 75 91 76 / 60 50 50 50
Fort Lauderdale 91 77 90 78 / 50 50 50 40
Miami 91 77 91 78 / 40 30 50 40
Naples 89 77 90 77 / 20 10 40 20
&&
.MFL Watches/Warnings/Advisories...
FL...None.
AM...None.
GM...None.
&&
$$
Area Forecast Discussion
National Weather Service Marquette MI
735 AM EDT MON SEP 19 2016
.SHORT TERM...(Today and tonight)
Issued at 507 AM EDT MON SEP 19 2016
WV imagery and RAP analysis indicated a strong zonal flow pattern
across the nrn CONUS upstream of the Upper Great Lakes with a 130-
140 knot 250-300 mb jet from the Pacific Northwest into the Northern
Plains. A vigorous shortwave trough at the nose of this jet max and
associated WAA has supported showers/t-storms over western Upper Mi
and Lake Superior early this morning. Elevated instability to near
1000 j/kg even supported a few stronger storms over western Lake
Superior which warranted the issuance of a special marine warning.
Elevated instability appears to be waning a bit in a past few hours
as airmass may be drying out and becoming more capped at mid-levels
per forecast soundings. This is reflected in weakening trend in
convection over north central Upper Mi in past hour. Convection
still going over eastern Lake Superior aided by lift 850 mb warm
front, but generally showing a weakening trend as well.
Today, the cold front will sweep through the cwa this morning into
early afternoon bringing gusty winds and drier air to the area with
gusts approaching 40 mph over the higher favored terrain of the
Keweenaw as noted on 00z forecast soundings. Although models show
best q-vector convergence and deeper moisture lifting generally
north and east of Lake Superior later this morning, there is another
pocket of q-vector convergence that moves into the south central and
eastern forecast area later this morning into the early afternoon
hours assoc with a secondary weaker shortwave now over the Dakotas.
Although models show drier air at mid-lvls there are a few hundred
j/kg of MLCAPE and low-lvl convergence along frontal boundary could
maybe touch off a few showers and possibly a thunderstorms over the
scntrl and ern fcst area by early-mid afternoon so wl include lower
chc pops for this possibility. Look for drier conditions later in
the afternoon as frontal boundary pushes se of Upper Mi. Sunshine
and mixing with 850 mb temps around 12C will support max readings in
the mid to upper 70s, possibly pushing 80F for west wind downsloping
locations over scntrl Upper Mi.
Drying and clearing skies along with diminishing winds will lead to
cooler conditions tonight especially over the interior, where min
temps will lower to 45 to 50. Tighter pressure gradient and more
winds/mixing will allow min temps to stay up a bit more near Lake
Superior. Look for min temps generally in the mid to upper 50s along
the Lake Superior shore.
.LONG TERM...(Tuesday through Sunday)
Issued at 438 AM EDT MON SEP 19 2016
Fast, progressive pattern to begin the long term will give way to an
amplified pattern during this week and into next week. Amplification
will occur due to a ridge/positive height anomaly shifting into the
Gulf of Alaska/western Canada by mid week. This in turn forces a
deepening trof over the western CONUS. The magnitude of the positive
height anomaly at 500mb will increase to 3 standard deviations above
the long term late Sept avg as it shifts across the Northwest
Territories to Nunavut late this week. Underneath this strong
positive height anomaly, the western CONUS trof will slowly progress
eastward. What eventually happens with this trof is highly uncertain
as spread among operational medium range model runs and CMC/GFS
ensembles in recent days is significant. With the CMC/GFS ensembles,
compared to recent days, there are more indicating that the trof
will never reach the Great Lakes, or at least not reach the area
during the next 7 days, as the energy drops out of the main flow and
settles into the sw CONUS. Mostly gone from the ensembles is the
GFS/ECMWF indication a day or so ago of the western trof going on to
become a large mid level low over the Upper Mississippi Valley/Great
Lakes region early next week. As the western CONUS trof amplifies
Tue/Wed, it will kick energy off the southern CA coast to the ne,
reaching the western Great Lakes Wed evening. This wave will bring
the next opportunity of widespread pcpn late Wed into early Thu.
Later Thu into Fri, pcpn fcst will hinge on strength of se Canada
troffing in response to the western Canada ridge. If the trof is
stronger, the baroclinic zone/frontal boundary will be forced far
enough s to allow for a period of dry weather later this week. If
not, the front will remain near the area to continue the chc of
pcpn. Recent days model runs and ensembles overall tend to favor the
former idea. As alluded to above, what happens over the weekend and
into Mon is highly uncertain, but it would appear pcpn chances will
increase again, unless the trof is left behind over the sw CONUS. As
for temps, above normal temps over the next couple of days will
trend down to around normal or even slightly blo normal during the
last half of the week as fcst area falls under low-level ne to e
flow with sfc front to the s and high pres ridge building into
northern Ontario.
Beginning Tue, expect a dry day under rising heights and a dry air
mass. After abundant sunshine to start the day, mid to high level
moisture streaking into the area will lead to an increase in
mid/high clouds from the w during the aftn/evening. Fcst soundings
suggest highs on Tue will top out mostly in the lower to mid 70s.
Dwpts will will be down into the 40s away from lake moderation.
Winds will still be on the breezy side across the Keweenaw on Tue,
but not as strong as today as pres gradient weakens with sfc high
pres ridge closer to the area.
Trof that will be amplifying into the western CONUS Tue/Wed will
pick up energy off the southern CA coast and send it ne, reaching
the western Great Lakes Wed evening. With pwat surging up to 1.5
inches and assistance of upper divergence associated with right
entrance of upper jet across northern Ontario/Quebec, expect shra to
overspread the area Wed/Wed night. There have been subtle overall
model trends to shift pcpn shield se a bit under slightly more
influence of se Canada troffing. Pops will show a gradient from low
chc nw to likely se. Pcpn will then diminish and/or end from nw to
se on Thu. Nw portion of the fcst area is most likely to trend dry
as sfc front drifts se with passage of shortwave.
Although there have been some inconsistencies from run-to-run,
overall model trend over the last day or so is for se Canada
troffing to be stronger heading into Fri, which seems reasonable
based on the strength of the positive height anomaly moving into n
central Canada. In addition, models are now tending to link up
ridging ahead of the western CONUS trof with that strong positive
height anomaly. All of this allows stronger sfc high pres ridging to
develop toward the Upper Lakes, pushing sfc frontal boundary farther
s. So, at this point, Fri is looking to be a dry day, but will hold
onto low pops across the s until this drier scenario has better run-
to-run consistency among the medium range models.
Over the weekend into Mon, fcst uncertainty is much higher than
normal for this time range. Both the 00z operational CMC and UKMET
have solutions similar to a number of GFS/CMC ensembles in settling
the western trof into the sw CONUS which could end up leaving dry
weather to prevail here this weekend. For now, fcst will maintain
some continuity with the idea that some form of the western trof
will eventually affect the area Sat thru Mon, resulting in pcpn
chc spreading back across Upper MI.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 732 AM EDT MON SEP 19 2016
Gusty west winds are expected to develop by mid morning today behind
a cold frontal passage, especially at CMX where gusts near 35 knots
are likely. Some isolated showers and maybe even a t-storm could
develop along the front this afternoon, but this activity is expected
to remain se of the taf sites. Expect VFR conditions at taf sites
through the period.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 507 AM EDT MON SEP 19 2016
Gusty s-sw winds will shift wsw later this morning into the
afternoon hours as a cold front move across the area. The tightening
pres gradient between high pressure area over the Plains and the low
assoc with the front tracking through northern Manitoba toward
Hudson Bay will result in WSW winds to 30 knots today in the wake of
the cold front. In fact, there could be a period of gale gusts to 35
knots between Isle Royale and the Keweenaw Peninsula this afternoon
as west-southwest winds will become enhanced by channeling between
these features. West winds should generally diminish to 25 knots Mon
night into Tue as gradient slackens with the Canadian low lifting
farther ne across Hudson Bay. Winds will diminish to less than 20
kts Wednesday into Friday under weak pres gradient across the Upper
Lakes.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...Rolfson
AVIATION...Voss
MARINE...Voss
Area Forecast Discussion
National Weather Service Omaha/Valley NE
1025 AM CDT MON SEP 19 2016
.UPDATE...
Issued at 1023 AM CDT MON SEP 19 2016
A very narrow band of MVFR clouds has developed immediately behind
the front, stretching from Columbus to just north of Denison, IA
at 1445z, and moving south. Have updated the Sky grids to reflect
this. And while this band does show up on KOAX 88D radar as a fine
line, the latest HRRR model runs suggest that this band should
not generate any precipitation.
&&
.SHORT TERM...(today through Wednesday)
Issued at 317 AM CDT MON SEP 19 2016
A continuation of warm temperatures through mid week is one
highlight of the forecast. The main concern however is when to
reintroduce thunderstorm chances.
Main upper flow pattern was characterized by strong westerlies
extending from off the Pacific Northwest coast across the Northern
Plains this morning. 130kt 300mb jet was noted punching into North
Dakota just past midnight. Surface cold front tied to upper low
spinning into northern Manitoba was arcing south and southwest
through Minnesota and into western Nebraska early this morning. That
front will progress east and southeast through eastern Nebraska and
southwest Iowa through the day, and settle along the Kansas border
into southeast Iowa by this evening. While there will be decent low
level moisture return ahead of the front as mid 60s dew points surge
into southeast Nebraska and southwest Iowa, layer moisture is
paltry. Models are in agreement that best combination of moisture
and forcing will lie well east of our area today, so will maintain
dry forecast. Wind will turn northerly behind the front today, so we
may shave a few degrees off recent highs in our north, but still
plenty of sunshine should push highs well into the 80s for most
areas.
Cold front is forecast to lift back north as a warm front Tuesday as
westerlies begin to buckle in the west as trough settles into the
Pacific Northwest. Downstream ridging will begin here, sufficiently
capping potential convection in eastern Nebraska and southwest Iowa
despite Mixed Layer CAPE topping 2000 j/kg in the afternoon. However
convection is expected to fire not too far north of our area Tuesday
evening/night north of retreating warm front where increasing low
level jet enhances forcing in northern Iowa. Given warming mid level
temperatures, south winds and plenty of sunshine, expect highs to
surge well into the 80s, and likely hitting the lower 90s in the
southern half of eastern Nebraska.
Southwest mid level flow overspreads the Plains on Wednesday as
western trough settles farther south along the coast. Both GFS and
ECWMF indicate a significant perturbation in that flow will be
entering eastern Nebraska Wednesday afternoon, while NAM portrays
this wave farther north. Expect surface frontal boundary to have
slipped a little south into eastern Nebraska as southwest upper
flow settles south, providing a focus for convection on which to
fire as instability increases during afternoon heating under
cooling temperatures aloft. Moisture return will not be robust as
easterly flow is maintained along the Gulf Coast much of the week.
However Pacific moisture plume is advertised at mid and upper
levels, and surface dew points in the mid 60s should remain in
place. Thus will maintain our current forecast of thunderstorms
firing Wednesday afternoon, especially in our north where frontal
boundary should lie. Highs again in the 80s are expected.
.LONG TERM...(Wednesday night through Sunday)
Issued at 317 AM CDT MON SEP 19 2016
A continued unsettled weather pattern will take us right through the
weekend as upper low/trough moves through the Rockies and into the
Northern Plains by Sunday. Rising heights ahead of system will lift
cold front north of our area on Friday, perhaps bringing a break to
convective activity for a time before trailing frontal system surges
into eastern Nebraska on Saturday.
Convection should expand along cold front Wednesday night with upper
impulse riding overhead. Convection will likely enhance
baroclinicity along front for Thursday and Thursday night, providing
focus for storms under increasingly diffluent flow aloft. With
rising heights Friday, front should lift into South Dakota leaving
our area under sufficient inhibition to limit storm potential much
of the afternoon and evening before cold front approaches from the
west on Saturday. Timing of all these features will likely change
with successive model runs, and finer details outlining severe and
heavy rain potential will be dealt with in time. Nonetheless there
will be several opportunities for stronger storms and pockets of
heavy rain during the longer term period.
&&
.AVIATION...(12Z TAFS for KOFK...KLNK and KOMA.)
Issued at 640 AM CDT MON SEP 19 2016
Mesoanalysis at 11z revealed a weak cold front stretching from
northwest Iowa through northeast into central Nebraska. An area of
IFR to MVFR visibilities due to fog have recently developed in a
corridor from KLCG to KOFK to KBVN, along the frontal wind shift.
This should be a short-lived condition with visibilities at KOFK
improving over the next couple of hours as mixing intensifies
within the post-frontal air mass.
The front will arrive at KOMA and KLNK around midday with south
winds veering to northwest and then north. Latest model guidance
suggests that fog potential tonight (Monday night/early Tuesday)
will be confined to the proximity of the front over far southeast
Nebraska. As such, VFR conditions are expected to prevail through
the forecast period.
&&
.OAX Watches/Warnings/Advisories...
NE...None.
IA...None.
&&
$$
UPDATE...DeWald
SHORT TERM...Dergan
LONG TERM...Dergan
AVIATION...Mead
Area Forecast Discussion...UPDATED
National Weather Service Pittsburgh PA
906 AM EDT Mon Sep 19 2016
.SYNOPSIS...
Building high pressure will result in dry conditions through the
week,
&&
.NEAR TERM /THROUGH TONIGHT/...
Minor adjustments to the forecast to add patchy fog through the next
hour and limit remaining showers the remainder of the morning to
far eastern zones as latest wv imagery fails to show any good
upstream forcing mechanism and latest RAP soundings largely shows
subsidence at forecast points across the region.
Hourly temperatures were adjusted better reflect latest
observational trends.
Improvement is expected tonight as surface high pressure builds in
the wake of the decisive frontal passage. Temperatures today were
forecast a couple degrees below most guidance given cloud cover
and convection expectations, while lingering humidity should hold
tonight`s lows up. Both periods are expected to be 5 degrees
above the averages which are 74 and 53 at Pittsburgh.
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY/...
Weak zonal flow with relatively dry surface high pressure is
progged to develop over the Upper Ohio during the mid week period.
Precip free weather is thus forecast with continued warm temperature
as per Superblend guidance.
&&
.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
Weekend rain chances appear to be slight as current progs of
dynamic support with a frontal passage are lacking as per the
latest GFS and ECMWF runs as well as ensemble guidance. No major
changes were thus needed for the long term which features warm
temperature about 5 to 10 degrees above the average.
&&
.AVIATION /13Z MONDAY THROUGH FRIDAY/...
Widespread IFR conditions with low level moisture pooling along
and ahead of a nearly stationary surface boundary across OH should
continue early this morning. A gradual increase in ceiling and
visibility is expected as mixing begins later this morning, and as
the surface boundary is driven east by a shortwave passage. A
return to VFR is expected by afternoon, with an eventual clearing
trend toward evening.
.OUTLOOK /TUESDAY THROUGH FRIDAY/...
General VFR is anticipated through the week outside of some
morning fog.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.
&&
$$
Area Forecast Discussion
National Weather Service Blacksburg VA
1003 AM EDT Mon Sep 19 2016
.SYNOPSIS...
An upper trough and frontal system will drift slowly east across
the forecast area today, then stall across the coastal plain of
Virginia and North Carolina Tuesday. The remnants of Tropical
Storm Julia will drift west into the Carolinas and linger along
the stalled front through late week. Meanwhile, high pressure will
build across the Tennessee Valley into the Mid-Atlantic region
during the later half of the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM EDT Monday...
Main focus of updating the grids will be to restructure POPs.
Meso models, especially HRRR, have a good handle on the current
band of heavy rainfall exiting Southside VA and the piedmont with
some additional shower activity moving through the higher terrain
in the west. As the heavy rain pulls off to our east, expect just
some lingering scattered showers through the afternoon.
Previous AFD...
Long awaited frontal system drifting across the western part of
the forecast area this morning. While most of the rain that fell
Sunday averted the RNK CWA, things are looking somewhat more promising
this morning as bands of showers redevelop along/in advance of the
slow moving frontal system and in right entrance region of upper
jet stream. HRRR seems to have a good handle on the pattern, so
largely used its suggest simulated reflectivity to gage pops. This
will keep high chance to low likely pops most areas through the
mid-morning then tapering off as conditions become less favorable
for this pattern to continue as the day progresses, along with
drier air spreading into areas west of the Blue Ridge.
Complicating factor throughout the period, and especially beyond
is the movement of T.D. Julia and its interaction with the frontal
system. Models differ considerably on how this will evolve with
the ECMWF/NAM drifting Julia west into and through NC/SC and
eventually into GA, while the GFS keeps the remnants of Julia tied
with the frontal boundary stalled along the NC coastal plain,
basically depicting a coastal front that lingers for several days.
Regardless of the model, it does appear that we will be dealing
with the moisture associated with Julia for days near or perhaps
in parts of the CWA. Therefore, have held onto low chance pops
east of the Blue Ridge even beyond 00Z Tue as moisture likely
spreads back northwest from T.D. Julia and the stalled frontal
boundary. Many uncertainties to deal with here, most of which lie
just beyond this forecast period.
Temperatures today should be quite a bit cooler than observed
Sunday with extensive cloud cover all areas and greater
precipitation chances in the east. Max temperatures will still be
above normal today, but on the order of 5-7 degrees instead of
10+ as in recent days. Min temps will remain well above normal,
50s west to 60s east. Keep in mind lows should be in the 40s west
to 50s east at this time of year!
&&
.SHORT TERM /TUESDAY THROUGH THURSDAY NIGHT/...
As of 300 AM EDT Monday...
Model guidance the past few days has been providing an array of
solutions regarding the interaction of the passing cold front and
the remnants of Julia. The solutions have included no interaction,
whereby in the wake of the cold front dry and mild conditions are
expected the remainder of the week. Solutions have also included
the remnants of Julia making slow progression westward onshore,
helping to stall the front over or near the southeastern part of
the region, all while streaming Atlantic moisture into our region
on an increasing easterly flow.
As time has progressed, more guidance, as well as, WPC, have been
leaning towards the latter over the former. While the forecast this
morning will not reflect the magnitude of precipitation into the
region as the 00Z/8PM operational ECMWF and NAM models provide, it
will start to lean toward a solution that has isolated to scattered
coverage of showers across the southern and eastern portions of the
region.
This scenario will also provide from more cloud cover and slightly
cooler than previously forecast high temperatures, especially in the
southern and eastern portions of the area.
&&
.LONG TERM /FRIDAY THROUGH SUNDAY/...
As of 415 AM EDT Monday...
Upper ridge strengthens by next weekend 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 shower
chances by day7. Temps to remain above normal, although tempered a
bit in the 70s Thursday by more clouds and again on Sunday per
possible showers. Otherwise highs mostly 80s and lows 50s to mid
60s.
&&
.AVIATION /14Z MONDAY THROUGH FRIDAY/...
As of 740 AM EDT Monday...
Convergence in advance of a slow moving frontal boundary and
combination of late Sunday evening sea breeze outflow and outer
fringes of T.D. Julia combined to bring bands of heavy showers and
thunderstorms to the areas along and east of the Blue Ridge. This
activity currently extends from KLYH to KDAN. All models,
including mesoscale models, indicate that this will lift northeast
out of the CWA by mid morning. A secondary area of less intense
activity along the actual front itself from KLWB to KBLF and
southwest. This will also move east and lift northeast through the
morning. The bulk of the heavier rainfall and associated localized
IFR-LIFR cigs/vsbys and widespread MVFR cigs will be this morning.
There remains a slight possibility for thunder again later this
afternoon across the Piedmont as the front nears that region, but
most of the thunder will be this morning.
As the front moves into and stalls across the coastal plain,
moisture will linger across eastern areas. Winds will initially
shift to the northwest behind the front west of the Blue Ridge,
but become northeast to the east as the remnants of T.D. Julia
drift into the eastern Carolinas. This will result in widespread
low stratus clouds and fog, mainly MVFR cigs in place much of the
night after 05Z.
Winds will be light and variable this morning east of the front,
becoming northwest 5-8 kts to the west, then as noted above
generally northeast to north-northeast this evening and overnight
at speeds of 4-6kts.
Medium confidence in cigs and vsbys through the TAF valid period.
Medium confidence in wind speed and direction through the TAF
valid period.
Medium to high confidence in thunder potential through 00Z.
Extended aviation discussion...
Tuesday through Friday, outside of late night/early morning
fog/low clouds, expect mainly VFR conditions with the caveat to
this being any lingering effects 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...MBS/RAB
SHORT TERM...DS
LONG TERM...JH
AVIATION...DS/RAB
Area Forecast Discussion
National Weather Service Tulsa OK
928 AM CDT MON SEP 19 2016
.DISCUSSION...
Notable mid-level height rises were noted on the 12z sounding
data this morning across OK/KS/MO/AR. This mid-level ridging will
bring hot and mostly dry weather to the region this week. A minor
update was made to the forecast to insert isolated shower/storm
mention mainly over the terrain of SE OK this afternoon. Short
term CAM models, namely the HRRR and HRRRX, have indicated for
several runs that there is some potential for mainly terrain-induced
isolated convection this afternoon, basically in the same area where
vis satellite shows high based accas this morning. No other changes
are needed to the going forecast.
Lacy
&&
.PREV DISCUSSION... /Issued 540 AM CDT MON SEP 19 2016/
AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
VFR conditions are expected to prevail through the valid period
at all area TAF sites.
PREV DISCUSSION... /Issued 357 AM CDT MON SEP 19 2016/
DISCUSSION...
An upper ridge will continue to build over the southern Plains
today and will persist for much of this week. This will result in
hot and humid weather, with afternoon high temperatures reaching
the upper 80s to mid 90s each day through at least Friday.
Afternoon heat index values will approach 105 in some places today
and Tuesday, but will back off some later this week as some drier
low level air advects into the area from the southeast.
The latest model runs have made a significant departure from
previuos runs in the handling of the western U.S. upper trough
late this week into next week. The strong upper ridge is now
progged to persist just to our east into next week, which keeps
the upper trough axis well to our west. Thus the chances of seeing
any significant frontal intrusions in the next week to ten days
have dropped dramatically.
We do expect daytime temperatures to begin to come down a bit by
this weekend into early next week due to increasing cloudiness.
Precipitation chances will also increase, especially in the
western part of the forecast area, but the strong upper ridge to
the east will limit the eastern extent of any significant
rainfall. We may have to wait until October now to get our first
real taste of fall weather.
Stayed close to guidance temperatures the next couple days.
TSA Watches/Warnings/Advisories...
OK...None.
AR...None.
$$
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 95 72 96 70 / 0 0 10 10
FSM 93 69 94 67 / 0 0 10 10
MLC 95 71 95 67 / 20 0 10 10
BVO 95 69 96 66 / 0 0 10 10
FYV 89 65 91 62 / 0 0 10 10
BYV 89 65 91 63 / 0 0 10 10
MKO 94 71 94 69 / 0 0 10 10
MIO 92 69 94 67 / 0 0 10 10
F10 95 72 95 69 / 0 0 10 10
HHW 95 71 95 69 / 10 0 10 10
&&
.TSA Watches/Warnings/Advisories...
OK...None.
AR...None.
&&
$$
SHORT TERM...30
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
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.
&&
.PREV DISCUSSION...
Issued at 205 PM EDT Mon SEP 19 2016
AVIATION...
A weakening cold front will drop through southern Michigan
overnight. Confidence is increasing in having a dry frontal passage
thus have kept any mention of precipitation out of the tafs. The
possible exception is MBS which may be far enough north to see a
stray shower before front weakens further. Will wait to see how the
front progresses this afternoon to possibly add vcts or a short
period of showers. Otherwise, mid/high clouds will increase tonight
along the front which will likely mitigate any fog development so
removed the MVFR visibility mention. Southwesterly flow will hold
into the overnight before veering to the northwest behind the front.
//DTW Threshold Probabilities...
* None
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...NONE.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
DISCUSSION...SF/DT
MARINE.......DRK
AVIATION.....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
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...
18Z UPDATE...
IFR to MVFR conditions that were in place early this morning have
transitioned mostly to FEW to SCT VFR for most locales. Still some
BKN conditions hanging on in the far east and south but even these
should abate with time late this afternoon. VFR conditions to
continue for the remainder of the TAF cycle with just a wind shift
to be concerned with at 06Z tonight which should send direction to
NE.
//ATL CONFIDENCE...18Z UPDATE...
High on all elements.
Deese
&&
.PRELIMINARY POINT TEMPS/POPS...
Athens 68 88 69 84 / 20 20 20 30
Atlanta 69 88 71 85 / 20 10 10 20
Blairsville 60 85 62 83 / 20 10 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...Deese
LONG TERM....01
AVIATION...Deese
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
226 PM CDT MON SEP 19 2016
.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 18Z TAFs...
Main forecast concerns this period will be with precip chances
this evening, and then with a wind shift to the north and
northeast tonight into Tuesday. As high pressure shifts to the
east, surface trough and frontal boundary will continue to
approach northern Illinois and northwest Indiana. In the near
term, this is providing for increasing southwest winds while
VFR/dry conditions prevail. Expect showers and thunderstorms to
develop along this boundary later this afternoon into the evening
but at this time, it`s appearing the more widespread and stronger
development will stay just to the northwest of all the terminals.
However, lingering precip could drift southeast into northern
Illinois possibly reaching the terminals. RFD will have the
highest chances for this precip with thunder a possibility, but
with these thunder chances lowering significantly through the
evening. If anything moves across the other terminals, have higher
confidence that they would only be showers. FROPA will take the
winds to the north and northeast this evening, with this shift now
appearing to be sooner tonight. VFR conditions will likely prevail
tonight into Tuesday, however, flow off the lake could provide
some lower clouds. Confidence is low at this time, and have
excluded any mention at this time.
Rodriguez
&&
.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.
&&
$$
VISIT US AT HTTP://WEATHER.GOV/CHICAGO (ALL LOWERCASE)
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:
WWW.FACEBOOK.COM/NWSCHICAGO
WWW.TWITTER.COM/NWSCHICAGO
WWW.YOUTUBE.COM/NWSCHICAGO
Area Forecast Discussion
National Weather Service Saint Louis MO
318 PM CDT MON SEP 19 2016
.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 18z TAFs through 18z Tuesday Afternoon)
Issued at 1254 PM CDT Mon Sep 19 2016
Dry and VFR conditions are expected through this evening. A front
will move into the area overnight which may produce isolated
showers and thunderstorms over west central Illinois. Do not have
enough confidence at this point to put this chance in the KUIN
TAF. Otherwise, expect there to be redevelopment of fog again late
tonight and early Tuesday, mainly along river valleys. Have placed
IFR visibilities at KSUS and KCPS between 08-13Z. Fog should
diminish by mid morning on Tuesday. Winds should be mainly light
through the period.
SPECIFICS FOR KSTL: Expect mainly dry and VFR conditions through
the period with light winds.
Britt
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
336 PM CDT MON SEP 19 2016
.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 18Z TAFS through 18Z Tuesday afternoon)
Issued at 111 PM CDT Mon Sep 19 2016
Cold front has just cleared EAU and precip will be going with. Outside
of a few mid level clouds, skies will be skc until late tonight
when wave currently over Wyoming brings another batch of mid levelclouds
in Tuesday morning. Some indications we may have another batch of
light rain/sprinkles as well, though moisture looks even higher
up than what we saw today.
KMSP...Wind direction will be tough to pin down the first couple
of hours, but the light winds will settle to SW this evening and
becoming increasingly southeastern during the day Tuesday.
/OUTLOOK FOR KMSP/
Wed...MVFR/Chc IFR. TSRA likely. E wind 5-15 kts.
Thu...MVFR/IFR. Chc of TSRA. NE wind 5-10 kts.
Fri...MVFR/IFR. Chc TSRA. E wind 7-10 kts.
&&
.MPX Watches/Warnings/Advisories...
WI...None.
MN...None.
&&
$$
SHORT TERM...MPG
LONG TERM...DWE
AVIATION...MPG
Area Forecast Discussion
National Weather Service Marquette MI
402 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 18Z TAFS through 18Z Tuesday afternoon)
Issued at 150 PM EDT MON SEP 19 2016
Gusty west winds are expected this afternoon behind a cold frontal
passage, especially at CMX where gusts near 35 knots are likely.
Light showers at/near SAW at the start of the period should move out
by 20z. Expect VFR conditions at 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...JLB
MARINE...JLB
Area Forecast Discussion
National Weather Service SAN ANGELO TX
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.
&&
$$