Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/12/16
Area Forecast Discussion
National Weather Service Birmingham AL
838 PM CDT SUN SEP 11 2016
.UPDATE...
Evening Update.
&&
.DISCUSSION...
All the thunderstorm activity has dissipated across central
Alabama. Scattered showers will continue across the far southern
counties through 10 pm. The stalled out front which pushed south
of Calera earlier today has likely drifted northward closer to
I-20 as low level winds from the upper air sounding are from the
southeast. Tuscaloosa is still reporting a light north wind so
the front was still south of this location. There is an extensive
cirrus shield over Alabama this evening, but the clouds should
thin out overnight and expect patchy fog to develop after midnight
for areas south of I-20.
58/rose
&&
.AVIATION...
00Z TAF Discussion.
Generally VFR conditions with isolated MVFR BR near MGM/TOI just
before sunrise. Boundary hangs around overnight producing areas of
light showers south of I-20. Currently, there are VCTS conditions
at TOI, but this should clear out over the next few hours.
Ceilings could lower overnight and into the morning across the
region, but should remain VFR. Light winds overnight with south
winds picking up to 5kts around 18z Monday.
25/Owen
&&
.FIRE WEATHER...
Shower and storm development will continue along/south of a
frontal boundary this afternoon/evening, impacting the
southeastern half of Central Alabama. Isolated to scattered rain
chances, mainly diurnally driven, continue through the week as
moisture remains high. No fire weather concerns are anticipated at
this time.
&&
.PREV DISCUSSION...
/Issued 638 PM CDT SUN SEP 11 2016/
SHORT TERM...
Tonight through Monday Night.
A quasi-stationary front was located from near Demopolis, to near
Clanton, to near Wadley this afternoon. The front is expected to
move very little through the overnight hours. The latest RAP
analysis indicates an unstable atmosphere in the vicinity of the
front. The various Cape measurements depict 2000-3000 values, DCape
values in the 800 neighborhood, decent low level lapse rates,
limited mid level lapse rates, and virtually no shear or winds
aloft. This will make storm motion rather slow and mergers and
outflows important. Some locations may receive up to two inches of
rain and some gusty winds. Small hail is also possible in the
strongest storms. The northward progression of storms will be
governed by outflows from the southern convection. Currently, the
rain chances have a very high gradient north to south due to this
uncertainty and position of the front. The storms will continue into
into the evening hours and a generally decrease by midnight.
On Monday, there will be some upper level energy moving west to east
into the area and additionally some weak wave moves northward into
the southeast areas. Currently have 50-55 pops advertised with the
uncertainty based on the convection today and how the airmass
recovers. If it does recover sufficiently, pops will need to be
raised tomorrow for the southern half of of the area. Once again,
some gusty winds, hail and locally heavy rain will be possible.
75
LONG TERM...
Tuesday through Saturday.
General upper level ridging will be in place across the region
thru the remainder of the week. Wind shear is expected to remain
non-existent under the ridge and there doesn`t appear to be any
significant forcing mechanisms. However, models continue to
indicate elevated moisture levels, generally PW values at or above
1.6 inches. This should be sufficient for some mainly diurnally
driven isolated to scattered convection each day thru the end of
the work. Did not make any major changes to rain chances. Temps
will be slightly above normal, highs in the upper 80s and low 90s
and lows in the upper 60s and low 70s.
Deeper southerly/southwesterly flow returns by the weekend as the
upper ridge shifts eastward and a trough deepens across the
central CONUS. In response, rain chances will be on the rise.
Models also try to push a front toward the Tennessee Valley in
the extended, but unfortunately, doesn`t look like it will have
enough support to push through. We`ll just have to keep waiting
for that first true taste of fall.
19
&&
.PRELIMINARY POINT TEMPS/POPS...
Gadsden 66 89 69 89 70 / 10 20 10 30 20
Anniston 69 89 69 88 70 / 20 40 20 30 20
Birmingham 70 91 71 90 72 / 10 20 20 30 20
Tuscaloosa 70 91 71 92 72 / 10 30 20 30 20
Calera 70 91 70 90 71 / 20 40 20 30 20
Auburn 72 88 70 88 71 / 50 50 30 40 20
Montgomery 71 93 72 92 73 / 50 50 30 40 20
Troy 68 91 69 89 71 / 60 50 30 40 20
&&
.BMX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Burlington VT
959 PM EDT Sun Sep 11 2016
.SYNOPSIS...
High pressure will provide ideal weather to the region tonight into
Tuesday night with dry weather along with seasonably cool nights and
mild to warm afternoons. The next chance for appreciable rainfall
will occur by later Wednesday into Wednesday night as a cold front
crosses the region with scattered showers and thunderstorms.
&&
.NEAR TERM /UNTIL 11 AM MONDAY MORNING/...
As of 959 PM EDT Sunday...Some leftover mid-level cloud cover has
developed along a surface trough seen as a slight NW wind shift in
METARs which extends from northern Coos county NH southwestward
across northern VT to just north of the northeastern shore of Lake
Ontario. Only effect these clouds are having are to slow stronger
radiational cooling across parts of these areas somewhat. Most
recent RAP shows these clouds if crudely, and I`ve opted to
increase sky cover through midnight and raise min temps up
slightly as well. All-in-all though, no huge changes to the
forecast for this evening. Expect areas of radiational fog in the
river valleys as cooling continues with lows ranging from the
upper 30s to upper 40s/near 50.
Previous near-term discussion issued at 302 PM follows...
Quiet weather expected tonight into Monday as deep layer high
pressure builds east across the region. Skies will trend mainly
clear with gusty west to northwesterly winds abating this evening
as p-gradient relaxes with approach of the surface ridge axis.
With nocturnal boundary layer winds trending light and recent
rains, patchy mist/fog a good bet later tonight in favored river
valleys/mountain hollows. Low temperatures a blend of mos-based
output supporting values mainly in the 40s, though a few 30s in
cooler northern mountain hollows and locally milder into the lower
50s in Lake Champlain shore communities.
By tomorrow abundant sunshine continues with winds trending light
southerly by afternoon as surface ridge edges east. Model-averaged
925 mb temperatures in the 18-21Z time frame are around 15C and
adding the typical 9C or so for this time of year yields highs
generally ranging through the lower and mid 70s.
&&
.SHORT TERM /11 AM MONDAY MORNING THROUGH TUESDAY NIGHT/...
As of 207 PM EDT Sunday...Quiet weather conditions with surface
high pressure in control southeast of New England. Will likely
see radiative fog Monday night in the favored valley locations
with overnight lows in the mid-UPR 40s, except locally lower 50s
vacant of Lake Champlain. A light S-SW return flow on Tuesday
will yield moderating temperatures under full sunshine; afternoon
highs expected in the UPR 70s to lower 80s.
Strong cold front and northern stream trough approaching by
Wednesday morning thus clouds increasing Tuesday night but should
be mainly dry with best chance across St. Lawrence Valley and
temperatures back into 50s- lower 60s.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 207 PM EDT Sunday...Timing of Cold front and upper trough
has shifted later and later...currently now expected midday/afternoon.
Dewpoints are in 50s-60s plus enough heating could produce CAPE
values 500-1000 j/kg and wind fields not as strong as recent event
but 850mb 30-40kts and 500mb >60kts suggest worth monitoring for
Wed afternoon.
Following FROPA, strong cold air advection with high pressure
building southeastward from south/central Canada will usher in a
seasonably cool airmass which will dominate our weather right
through the end of the work week. Good radiative cooling and much
drier air suggests the first frost of the season is possible in the
Adirondacks and sheltered valleys of Vermont`s Northeast Kingdom
early Friday morning. High Temperatures moderate back into the low-
mid 70s Friday/Saturday afternoon, as low-level flow turns southerly
in advance of next shortwave trough crossing the Great Lakes.
There are some timing differences in the details for next system but
will go with chance of afternoon showers Saturday with greater
threat Sat ngt and Sunday.
&&
.AVIATION /02Z Monday THROUGH Friday/...
Through 00Z Tuesday...VFR FEW-SCT fair weather cu should go to
VFR SKC shortly. Winds begin northwesterly around 10 kts but will
slacken as ridging builds into the North Country. Clear skies and
the light winds will go to produce LIFR to VLIFR fog at MPV and
SLK, starting the soonest at SLK (around 04z) due to winds
lightening there the earliest. VFR SKC conditions continue into
Monday as high pressure centers itself south of the region. Winds
initially light to calm but become southerly around 3-7 kts
Monday.
Outlook 00Z Tuesday through Friday...
00Z Tue - 18Z Wed: Mainly VFR under high pressure except LIFR
nocturnal fog possible SLK/MPV 06-13Z each morning.
18Z Wed - 06Z Thu: VFR with MVFR possible in showers/isolated
storms with cold frontal passage.
06Z Thu onward: VFR under high pressure.
&&
.BTV WATCHES/WARNINGS/ADVISORIES...
VT...None.
NY...None.
&&
$$
SYNOPSIS...JMG
NEAR TERM...JMG/Loconto
SHORT TERM...Banacos/SLW
LONG TERM...Banacos/SLW
AVIATION...JMG/Loconto
Area Forecast Discussion
National Weather Service Duluth MN
1030 PM CDT SUN SEP 11 2016
.UPDATE...
Issued at 1030 PM CDT Sun Sep 11 2016
Showers are trying to spread into Koochiching county at 0330Z.
Have made some tweaks to account for pops with this initial surge.
HRRR/RAP continue to insist on more showers after a brief break
overnight. Added pops late as a result.
UPDATE Issued at 750 PM CDT Sun Sep 11 2016
Thunderstorms have developed north of Grand Forks, with showers
extending northeastward to near Roseau. Latest HRRR runs point to
these showers and isolated storms move through the northern tier
of the region through the rest of the evening. Have added a
mention of showers as a result. Held off on the thunder mention as
best instability remains west of the area. Also made some other
adjustments.
&&
.SHORT TERM...(This evening through Monday)
Issued at 254 PM CDT Sun Sep 11 2016
The week ahead will turn much cooler due to a cold front that will
come through on Monday and Monday night.
The front was over northwest North Dakota this afternoon with a
shield of clouds and rain along and on the cool side of the front.
Extra lift was supplied by a strong short wave that was ejected from
the deep long wave trough digging into the southwest. The models are
in good agreement to bring the front into northwestern MN late
tonight, then in to the Duluth forecast area Monday morning and into
northwest Wisconsin Monday evening. Very strong warm air advection
is occurring ahead of the front where low level winds of 30 knots
has been bringing up 8h temps well into the teens and moisture
will also be increasing with sfc dewpoints expected to climbing
into the 50s. By Monday afternoon there will be enough instability
with MUCAPES from 1k to 2k j/kg that showers and storms could
develop.
.LONG TERM...(Monday night through Sunday)
Issued at 254 PM CDT Sun Sep 11 2016
The cold front will move out northwest Wisconsin Monday evening.
There could be some showers and thunderstorms during the evening
hours during the frontal passage. A ridge builds into the region on
Tuesday bringing in the first shot of fall-like air into the region.
Models indicate 85H temps will drop to 1-3C across areas along and
north of the iron range and inland areas of the Arrowhead. Low
temperatures are expected to drop to the middle to upper 30s in
those areas causing light frost. The one thing that could keep the
frost from occurring is lingering clouds from Tuesday afternoon
keeping the temperatures higher in the evening.
The ridge will dominate the weather on Wednesday and Thursday. The
ridge will be moving east of region by late Wednesday causing a
southerly flow to develop increasing the moisture and temperatures
across the area. A slow moving low pressure area will move through
the northern plains on Thursday and the Upper Midwest on Friday. The
timing and location of the low center is different on the models.
The ECMWF has the center further north than the GFS with the ECMWF
faster than the GFS. Either way, the region will be receive
showers and thunderstorms.
An area of high pressure will build into the region on Saturday but
there will be some lingering moisture in the area. There may be
some lingering showers on Saturday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 650 PM CDT Sun Sep 11 2016
VFR through much of the forecast. As the cold front moves into
northeast Minnesota by noon, look for MVFR ceilings to begin to
spread across the terminals. Showers will occur near the front as
it moves southeastward through the rest of the afternoon and into
the evening. Thunderstorms are possible, but confidence is low on
where and when they will affect the terminals. Some LLWS is
expected this evening as a low level jet moves through the area.
This LLWS should diminish shortly after sunrise.
&&
.PRELIMINARY POINT TEMPS/POPS...
DLH 56 70 52 60 / 0 30 30 10
INL 54 64 45 55 / 40 20 10 30
BRD 55 70 50 62 / 0 20 20 0
HYR 55 74 54 63 / 0 30 50 20
ASX 57 74 55 62 / 0 30 60 20
&&
.DLH Watches/Warnings/Advisories...
WI...None.
MN...None.
LS...Small Craft Advisory until 1 PM CDT Monday for LSZ140.
&&
$$
UPDATE...GSF
SHORT TERM...CLC
LONG TERM...Stewart
AVIATION...GSF
Area Forecast Discussion
National Weather Service Wilmington NC
1022 PM EDT Sun Sep 11 2016
.SYNOPSIS...
A cold front in the area will slowly dissipate through Tuesday.
High pressure will reach down into the Carolinas Wednesday as a
trough extends up the coast from Florida. Another cold front will
drop south into North Carolina Thursday. High pressure will build
south behind the front late week before sliding off the coast this
weekend.
&&
.NEAR TERM /THROUGH MONDAY/...
As of 1022 PM Sunday...Recent satellite data shows convective
debris clouds in variable but significant amounts will remain
overhead overnight. This appears to be captured well in blends of
the SREF and RAP models. Ramifications to minimum temperatures are
likely and have upped hourly temperature values into early MON,
also implied by the aforementioned near-term models.
As diurnal buoyancy over the waters approaches peak into pre-dawn
and daybreak, isolated to scattered ocean showers should find
their way onshore into the Cape Fear region after 4 AM, and have
played slightly higher pop values near the coast into early MON.
No other appreciable modifications were made with a relatively
sultry early morning to prevail for September 12th. The previous
discussion follows.
Isolated strong TSTMS popped and pulsed with aid from the sea
breeze boundary as a frontal boundary neared the coast. Post peak
heating taking a toll on convection at this time and pops as well
as sky cover were reduced to reflect the present weather.
Otherwise no changes and will hold onto at least isolated pop
values for the overnight period. Minimums daybreak Monday 70 to 73
inland and 73 to 76 closer to the sea in light onshore flow.
&&
.SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
As of 300 PM Sunday...A weak cold front will be in the vicinity
Monday, but should already be in the dissipation process later in
the day. Onshore flow and much more in the way of cloud cover will
finally result in daytime temps more typical of mid September.
Although the lowest levels of the column will be rather dry,
considerable moisture will exist aloft with near saturation through
a significant depth. Weak shortwave energy working through the FA in
such an environment should help to initiate/continue the risk for
showers and thunderstorms. Weak instability, mixed layer Cape values
around 500 J/kg, support showers over thunderstorms, but can not
rule out a few thunderstorms. The risk for convection will diminish
significantly Tue night.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 300 PM Sunday...High pressure extending down from the
northeast will continue to move farther off shore leaving a decent
SE return flow of moisture into the Carolinas through Wed. Also,
GFS shows tropical wave/trough aligned up the SE coast from Florida
Wed with high pressure just east. This should provide a decent
flow of moisture onto the southeast coast. Pcp water values remain
up around 2 inches and higher further south. Expect mainly mid to
high clouds to reach up into the area from the convection to our
south and also some shwrs developing along trough mainly over
coastal waters to the south and east and to a lesser extent over
land through Wed into Thurs.
At the same time, the surface high quickly migrates eastward as
the next cold front gets pushed southward into NC by Wed night.
Believe best chc of deeper convection will remain south, but there
will be some forcing along and ahead of the cold front as it
reaches toward area on Thurs. The northern stream shortwave
driving the front moves quickly off the northeast coast by late
Thurs with a building ridge behind it, and, the expansive area of
high pressure reaching down from Canada behind the front moves
quickly east. Therefore it is debatable as to how far south the
front will make it. For now, looks like we remain on the southern
extent of high with lingering boundary or moisture near or just
south through Fri.
As this high shifts off the Mid Atlantic coast by Saturday, the
winds will shift back around to the E-SE with building ridge
aloft up through the southeast. Therefore, the lower dewpoint air
behind front will be replaced by a more humid air mass heading
into the latter half of next weekend as coastal trough pushes
inland. But, the ridge should maintain subsidence aloft and less
chc of any pcp and clouds, although the GFS maintains a greater
chc of shwrs and clouds, mainly over South Carolina through next
weekend aligned with coastal trough. Overall not that confident as
to how much pcp we will actually get through the long term period.
The drier air behind cold front should reach into our area Thurs
night into Fri with lower and near normal overnight lows and a
cooler start to the day on Fri and Sat but expect a return to a
more humid air mass by the latter half of the weekend. Daytime
highs should reach into the low to mid 80s with coolest and less
humid days on Fri and Sat and warmer and more humid days on
Wed/Thurs and again on Sunday.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
As of 00Z...Quite a bit of uncertainty over the next 24 hours. The
models are not in good agreement, not only with respect to cloud
ceilings, but the amount of precip coverage. The NAM is the most
pessimistic, with IFR ceilings overnight, with decent pops on
Monday. The GFS has VFR conditions all night with only scattered
precip tomorrow. The front will be weakening and should not have
much movement through the period. Will keep quite a bit of clouds of
varying heights through the TAF period, as well as light and varying
winds at most locations.
EXTENDED OUTLOOK...Increased chance for convection through Friday
with a weak front stalled in the area. Brief bouts of IFR are
possible in the heavier convection.
&&
.MARINE...
NEAR TERM /through tonight/...
As of 1022 PM Sunday...Offshore high pressure will weaken on its
western periphery, allowing a cold front to approach the coastal
waters around or after daybreak Monday. S to SW winds will prevail
much of the overnight 10-15 KT. Seas will remain 2 to 3 ft with
polar plots and sea spectrum tabular data showing the bulk of wave
energy will remain linked to short period SSW-S waves. An uptick
in ocean showers is expected between 4AM-8AM, favored around Cape
Fear, and a few cloud to sea lightning strikes cannot be ruled out
into pre-dawn through sunrise.
SHORT TERM /Monday through Tuesday night/...
As of 300 PM Sunday...A weak cold front will slowly dissolve in
close proximity later Mon with weak ridging returning on Tue. This
will generally keep easterly winds across the waters. Wind speeds
will be around 10 kt or less. Seas will be 2 to 3 ft. Isolated to
scattered showers and thunderstorms will remain in the forecast
through the period.
LONG TERM /WEDNESDAY THROUGH FRIDAY/...
As of 300 PM Sunday...Models continue to show a wave/trough
feature reaching up the southeast coast with high pressure to the
east on Wed producing winds shifting from E-NE in the morning to
SE through the day. At the same time a cold front will drop south
into NC by Thurs and models are backing off the southern push of
this front as high pressure behind it moves rapidly east with
center reaching the Mid Atlantic coast by Fri morning. As this
cold front drops south Wed night into Thurs, winds will shift to
the NE, but will come around to the E-SE through Fri as high
pressure to the north moves off the east coast. WNA shows increase
in seas from 2 to 3 ft Wed into Thurs up to 4 ft in outer waters
by Fri.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...ILM
NEAR TERM...MJC
SHORT TERM...RJD
LONG TERM...RGZ
AVIATION...43
MARINE...MJC/RGZ
Area Forecast Discussion
National Weather Service Marquette MI
747 PM EDT SUN SEP 11 2016
.SHORT TERM...(This evening through Monday)
Issued at 353 PM EDT SUN SEP 11 2016
Water vapor imagery and RAP analysis show pattern transitioning to a
lower amplitude flow. Broad low amplitude ridge is pushing into the
Great Lakes region ahead of a positive tilt trof extending from
northern Manitoba to the Pacific NW. This trof will bring the next
opporunity of pcpn Mon night into Tue. Mid and high clouds that
spread into the area this morning have been thinning out and have
been replaced by sct to at times bkn cu. To the nw across ne MN into
northern Ontario where best waa/isentropic ascent is occurring,
mid/high clouds clouds persist. Temps across the fcst area have
risen into the lower 70s for the most part.
Despite continued waa/isentropic ascent tonight, relative dryness of
the air mass advecting into the area will ensure pcpn is of no
concern. In fact, fcst soundings suggest not much in the way of
cloud cover. Steady sw winds will limit the temp fall tonight with
many downslope locations near Lake Superior probably not falling blo
60F. At the interior cool spots, temps shouldn`t fall blo 50F.
On Mon, aforementioned positive tilt trof will shift e, extending
from Hudson Bay to the northern Rockies. Disorganized shortwave
energy in the trof will slowly push associated cold front across MN
and out over western Lake Superior in the late aftn/early evening.
Consensus of 12z model runs has been to slow down slightly the
progress of the cold front. Given the dry air mass ahead of the
front, shra and possible tsra will likely be confined to right along
or more likely just behind the sfc cold front. Have thus dropped
schc pops over the far w prior to 00z. With fcst soundings
suggesting abundant sunshine, raised max temps a bit with much of
the area likely to be in the 75-80F range. Fcst sounding suggest max
temps could be mostly around 80F away from Lake Michigan.
.LONG TERM...(Monday night through Sunday)
Issued at 315 PM EDT SUN SEP 11 2016
Forecasted upper air pattern shows a 500 mb trough in the western
U.S. and a shortwave in the northern plains and a broad 500 mb ridge
across the ern U.S. 00z Tue. This shortwave moves southeast and
affects the upper Great Lakes on Tue and Tue night. Nam shows some
850-500 mb q-vector convergence moving in for Mon night along with
some deeper moisture with the moisture remaining on Tue while the q-
vector convergence moves out. Does get cold enough aloft at 850 mb
off the nam, gfs and ecmwf tue night into Wed morning for lake
effect pcpn as 850 mb temperatures are from 4C to 6C while Lake
Superior temperatures are from 16C to 19C which is enough lake-850
mb delta-t for clouds and some lake effect rain showers. Kept in
chance pops for north lake effect pcpn belts for Tue night and Wed
morning. Did go likely pops for Mon night into Tue morning. Overall,
did not make too many changes to the going forecast for temperatures.
In the extended, GFS and ECMWF show a 500 mb ridge across the Ern
U.S. and a trough in the Rockies and western high plains 12z Thu.
This trough moves into the northern and central plains 12z Fri and
into the Upper Great Lakes 12z Sat. This trough remains over the
area into Sun, so the area will see this storm system from Fri into
Sun. Temperatures look to be near normal for this forecast period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 734 PM EDT SUN SEP 11 2016
Although high pres ridge is shifting e and a cold front is moving
across the Northern Plains, the low-level air mass will remain dry
across the area during this fcst period, allowing VFR conditions to
continue at KIWD/KCMX/KSAW. As the pres gradient tightens btwn the
exiting high pres ridge and the approaching cold front tonight
stronger sw winds just off the surface above the noctural
radiational inversion will result in LLWS at KCMX/KSAW tonight.
Expected gusty sw winds at IWD through the night will eliminate the
need for LLWS mention there.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 353 PM EDT SUN SEP 11 2016
Tightening pres gradient btwn departing high pres ridge and an
approaching cold front will result in increasing s to sw winds to 20-
30kt tonight into Mon. Some gale force gusts will probably occur at
the higher observation platforms over n central Lake Superior,
especially btwn Isle Royale and the Keweenaw Peninsula. Winds will
shift to the nne Mon night into Tue following the cold frontal
passage, but these winds are not expected to be higher than 20-25kt.
Arrival of high pres on Wed will result in winds diminishing to
under 15kt. Winds will then become southerly and should remain 20kt
or less Thu/Fri.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...07
AVIATION...Voss
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Raleigh NC
1006 PM EDT SUN SEP 11 2016
.SYNOPSIS...
A cold front will move southwest across central NC tonight, then
dissipate as it drifts into the Southeast states through Tuesday.
High pressure will otherwise extend across the Middle Atlantic
states.
&&
.NEAR TERM /TONIGHT/...
As of 1000 PM Sunday...
Earlier convection that focused along 1) a lee trough over the SRN
Coastal Plain and 2) a backdoor frontal segment over the NRN Coastal
Plain, has diminished and/or moved E during the past couple of
hours. The latter feature --now reinforced by convective outflow and
evident as a radar fine line/arc in KRAX reflectivity data-- will
serve as the principle focus for any additional shower and weak
storm development as it drifts SWWD into the SRN/SWRN half of the
RAH CWFA, through an area of lingering weak instability as far west
as the upstate of SC, overnight. This boundary will also focus low
level moisture convergence, and weak isentropic upglide as the 925
veers to SSE per model forecasts, which will probably culminate in
the development of a band of low overcast, and perhaps some
preceding fog, mainly across the SRN Piedmont/ Sandhills/SRN Coastal
Plain (roughly S of HWY 64). Despite the passage of the front, the
post-frontal air mass isn`t markedly cooler, at least not S of the
Mason Dixon line as of 02Z, so temperatures will remain mild and
above average in central NC tonight - in the middle 60s to lower 70s.
&&
.SHORT TERM /MONDAY AND MONDAY NIGHT/...
As of 340 PM Sunday...
After 5 consecutive days of highs in the 90s at most locations in
central NC, Monday will feature noticeably cooler temperatures.
The cold front will likely stall near the South Carolina border on
Monday and Monday night providing a weak focus for mainly
afternoon and evening convection and supporting a good deal of
cloudiness across the area. Best precipitation chances will be
across the south near the front and closer to deeper moisture
while drier and more stable conditions near the VA border should
result in little to no shower activity. High temperatures will
range in the lower 80s northwest to mid 80s far southeast.
More of the same for Monday night with partly to mostly cloudy
skies and a small chance of showers across the south. Some pockets
of drizzle may develop develop overnight, mainly across the
western Piedmont and Yadkin Valley area after midnight. Low
temperatures will range in the mid to upper 60s. -Blaes
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 200 PM Sunday...
Tuesday through Thursday: Tuesday the frontal zone washes out south
of the area but a fair amount of residual moisture will be left over
and and precipitation chances will extend northward through the
southern counties up to about highway 64. Instability is almost non-
existent in the latest forecast soundings and so showers will be the
most likely mode of precipitation. Some of that instability returns
on Wednesday and and so showers and thunderstorms will still be
possible, again with the main threat across the southern counties
and everyone else remaining mostly dry. On Wednesday night a cold
front is progged to move through the area as a dry front with
showers and thunderstorms in the afternoon on Thursday again across
the southern tier as diurnal timing becomes more favorable. Highs in
the upper 80s Tuesday and Wednesday will be cut back to the lower
80s on Thursday after the frontal passage.
Friday through Sunday: High pressure to the northeast takes over the
pattern for the weekend bringing moist easterly flow across the
area and possibly helping to increase cloud cover in the west as
moisture banks up against the mountains. Aside from that, mostly dry
conditions are expected during this time period with temperatures in
the low to middle 80s, warmest late in the weekend as a more
southerly component returns to the flow ahead of a more robust
frontal system that will approach the area early next week.
&&
.AVIATION /00Z MONDAY THROUGH FRIDAY/...
As of 822 PM Sunday...
A cold front will move slowly south through the area this evening
and into the overnight hours, where it is then expected to stall
invof of the South Carolina state line on Monday. Waning instability
from loss of daytime heating will further decrease convective
coverage over the next hours with only isolated showers expected as
the front pushes south, and largely confined to across
southern/southeastern areas invof KFAY.
Models are in disagreement with the development of scattered to
broken MVFR ceilings behind the front between 06 t0 12z as low-level
nely develops. The NAM is the most emphatic, while the GFS and most
recent HRRR show less in the way of sub-VFR ceilings. As such
confidence is low and will include tempo groups for MVFR ceilings
between 08 to 12z at all TAF sites.
The stratus could persist into the mid morning hours and perhaps
midday across the south with VFR conditions returning on Monday
afternoon.
Looking further ahead... Generally VFR conditions are expected for
Monday and Tuesday with a small threat of some isolated to scattered
afternoon and evening convection across the south and southeast
including KFAY. Another cold front will cross the region
Wednesday night with just a small threat of showers. Fair weather
is expected behind the front for Thursday into Friday.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...MWS
NEAR TERM...MWS
SHORT TERM...BLAES
LONG TERM...RE
AVIATION...CBL/BLAES
Area Forecast Discussion
National Weather Service Grand Junction CO
356 AM MDT MON SEP 12 2016
.SHORT TERM...(Today through Tuesday)
Issued at 356 AM MDT Mon Sep 12 2016
Broad southwest flow will remain in place across the region over
the next few days. Energy kicking out of the closing low will be
pushing through the forecast area with breezy to windy conditions
expected, especially over our higher terrain. One wave will be
exiting our northern zones this morning, a second arrives over the
Four Corners this afternoon and another push is expected later
Tuesday.
As for the finer details...isolated showers and thunderstorms
hanging on this morning across northwest Colorado with a few
remote sites kicking out wind gusts between 35 and 40 mph. HRRR
and RAP keep the high based showers rolling northeast across our
northern zones through mid-morning before drier conditions sweep
back in. Focus of convective activity then shifts south into our
southern zones as a shortwave lifts northeast out of Arizona and
through the San Juans. This wave will be arriving just in time for
peak heating and will be working on moderate moisture pooling near
the Four Corners to kick off another round of storms. This
activity will be a little better organized and should persist into
the evening hours with light QPF amounts.
Moving back to the north, the drier air mass that will be pushing
in this afternoon will allow humidity values to drop back below
critical fire weather thresholds. With winds increasing and gusting
over 25 mph will be issuing another Red Flag Warning. Details
below in our fire weather discussion.
Convection and critical fire weather conditions ease overnight
with moisture improving a bit by Tuesday afternoon as another wave
works through bringing more afternoon showers and thunderstorms.
Temperatures will be down a few degrees today with continued
cooling expected on Tuesday, trending toward below normal
readings in most areas.
.LONG TERM...(Tuesday night through Sunday)
Issued at 350 PM MDT Sun Sep 11 2016
A stronger trough closes over CA-NV then slowly lifts into
Wyoming by Thursday. Precipitable water climbs to 0.75 inch
Tuesday night and Wednesday. Some cooling aloft increases
instability and thunderstorm/shower coverage. Mountain top winds
remain SW of 25 to 35 mph and these winds will mix down into the
valleys with storms.
The trough and its -16C cold core pass over the region Thursday
with SW winds shifting and weakening to NW. Moisture diminishes
with isolated showers limited to the eastern mountains Thursday
and Friday. Temperatures will be below normal.
Saturday-Sunday, high pressure builds over the northern Rockies
with a dry north flow on Saturday turning to east on Sunday.
Moisture may begin to work into the Four Corners region early next
week.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 356 AM MDT Mon Sep 12 2016
VFR conditions expected at all terminal sites today with locally
gusty winds up to 35 mph expected this afternoon. Scattered
showers and thunderstorms will develop over the southern mountains
this afternoon with storms tracking northeast into the central
mountains and valleys in western Colorado. Storms diminish after
06z. Expect gusty outflow winds and only light rainfall amounts.
The best chance for any impacts due to showers will be over KTEX,
KDRO, KASE and KEGE after 21z on Monday.
&&
.FIRE WEATHER...
Issued at 356 AM MDT Mon Sep 12 2016
Another push of drier air will spread across northeast Utah and
northwest Colorado today with deep mixing driving down stronger
winds aloft. Expect several hours with humidity values below 15
percent and peak wind gusts from 25 to 35 mph. With fuels still
critical, will be issuing another Red Flag Warning from later this
morning through mid-evening for Colorado Fire Zones 200 and 202
and Utah Fire zone 487.
&&
.GJT Watches/Warnings/Advisories...
CO...Red Flag Warning from 11 AM this morning to 8 PM MDT this
evening for COZ200-202.
UT...Red Flag Warning from 11 AM this morning to 8 PM MDT this
evening for UTZ487.
&&
$$
SHORT TERM...JDC
LONG TERM...Joe
AVIATION...JDC
FIRE WEATHER...JDC
Area Forecast Discussion
National Weather Service Wilmington NC
315 AM EDT Mon Sep 12 2016
.SYNOPSIS...
A cold front will enter the area today and slowly wash out
through Tuesday. The next cold front will arrive Thursday.
High presure to our north will move eastward over the weekenend.
&&
.NEAR TERM /THROUGH TODAY/...
As of 300 AM Monday...The surface cold front at 3 AM extends across
south-central North Carolina from Hatteras to Greenville and Fort
Bragg to Rockingham. After moving little through the night, the
front should get a shove southward this morning as high pressure
over the Great Lakes moves into Pennsylvania. This should kick the
boundary southward at least as far south as Myrtle Beach/
Marion/Kingstree. Overnight thunderstorms continue to redevelop
across the area, dropping locally heavy rainfall. Latest HRRR runs
indicate this activity should last another couple hours but should
diminish toward sunrise.
The big southeastern upper ridge has been beaten down over the past
several days and the mid-latitude westerlies now extend into
Tennessee and the Carolinas. A belt of deep moisture along the
southern edge of the westerlies covers the eastern Carolinas.
Precipitable water should hold at 1.8 to 1.9 inches today, and given
the nearby front plus CAPE values of at least 1000 J/kg I expect
redevelopment of showers and thunderstorms early this afternoon. The
best coverage should follow the front plus a weak seabreeze that may
develop this afternoon. PoPs of 50-60 percent are forecast from
Wilmington to Myrtle Beach, and Conway to Kingstree.
Highs should range from 82-87, coolest on the NC beaches.
Convective activity should diminish this evening, but may continue
out over the coastal waters where a more unstable airmass will
persist overnight. Lows 69-74.
&&
.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
As of 300 AM Monday...The upper level ridge will rebuild itself off
the Southeast coast Tuesday and Wednesday. At the surface, high
pressure off the New England coast will linger through Wednesday
morning before the next storm system shoves it out to sea.
Frontolysis, warming mid and upper level temperatures, and the
advection of slightly lower dewpoints in from the northeast will
both help to reduce (but not eliminate) the chance of showers and
thunderstorms both days. Forecast pops are 30-50 percent Tuesday and
fall to 20-30 percent by Wednesday, even as temperatures rise back
into the mid to upper 80s by Wednesday.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
As of 3 AM Monday... Cold front stalled over the area on Thursday
and we may be able to refine to show slightly higher rain chances
south of where ever the front stalls. These rain chances may not be
all that great though with weak mid level ridging overhead. Rain
chances decrease to just slight chance on Friday as some cooler high
pressure noses in from the north. Models do show that just south of
this ridge there may be some better rain chances, and this may
impinge upon western zones. Again this depends on how far south the
moisture gets shoved. Over the weekend the high progresses offshore
while staying well to our north. Locally we will get into a flow of
deeper moisture while the mid levels remain fairly non-conducive for
ascent. Surface level features will be alone in contributing to what
will likely be isolated showers.
&&
.AVIATION /06Z MONDAY THROUGH FRIDAY/...
As of 06Z...Confidence remains a little low though overall impacts
to aviation as a whole likely only confined to possible IFR CIG
and/or VSBY just during predawn. And since guidance was split on
this have opted not to show such pessimistic conditions. Showers and
very isolated thunder dotting the radar and this activity likely to
congeal between ILM and LBT and then dissipate towards daybreak.
With a dissipating frontal boundary in the area for the rest of the
period showers will return with isolated to widely scattered
coverage and be possible at all terminals Monday afternoon. They too
likely to dissipate towards sunset. The proximity of the boundary
also to keep winds light and variable.
EXTENDED OUTLOOK...Increased chance for convection through Friday
with a weak front stalled in the area. Brief bouts of IFR are
possible in the heavier convection.
&&
.MARINE...
NEAR TERM /Through Tonight/...
As of 300 AM Monday...Bermuda High Pressure centered over Bermuda
should weaken throughout the day. High pressure currently centered
over Pennsylvania will move east and off the southern New England
coast by this evening. This should push a cold front, currently
almost stationary across central North Carolina, southward through
the Cape Fear and Grand Strand area this morning. This boundary
should wash out as the New England high "bridges" southward into
what`s left of the Bermuda ridge, creating an unbroken zone of
easterly winds extending from New Jersey down to Florida by tonight.
Light SW winds this morning should turn easterly a few hours after
sunrise, with wind speeds remaining 10 knots or less throughout the
day. Seas currently 2-3 feet should average around 2 feet this
afternoon and tonight.
SHORT TERM /Tuesday through Wednesday night/... As of 300 AM
Monday...High pressure off the New England coast will linger through
Wednesday morning until forcibly ejected by the next incoming storm
system from the west. This erosion of the ridge should finally allow
our surface winds to veer more southerly rather than easterly. Wind
speeds are expected to remain rather light through the period with
the exception of Tuesday when the east-northeasterly for a period.
The next cold front may arrive late Wednesday night, again pushed
southward more by the incoming area of high pressure than any else.
LONG TERM/THURSDAY THROUGH FRIDAY/... As of 3 AM Monday...Light
northerly wind to start Thursday with a cold front pushing through.
Behind the boundary flow will veer to onshore and pick up a bit as
high starts to build in from the north.
This should introduce 3 ft seas. We maintain similar wind and waves
on Friday as the high well to our north only slowly moves eastward.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...MBB
NEAR TERM...TRA
SHORT TERM...TRA
LONG TERM...MBB
AVIATION...MBB
Area Forecast Discussion
National Weather Service Marquette MI
404 AM EDT MON SEP 12 2016
.SHORT TERM...(Today and tonight)
Issued at 403 AM EDT MON SEP 12 2016
00Z raobs/latest wv imagery and RAP analysis show some lo amplitude
upr rdging centered over the wrn Great Lks downstream of a deepening
upr trof over the Pac NW coincident with a shrtwv digging into that
area. An acyc sw flow arnd hi pres over the Mid Atlantic states/dry
capped environment depicted on the local 00Z raobs are bringing
tranquil wx to the cwa this mrng, with just some mainly hi clds
spreading ovhd. The tightening pres gradient btwn the departing hi
pres and a cold fnt stretching fm nw Ontario into the nrn Plains
attendant to a shrtwv lifting enewd thru scentral Canada has
resulted in some gusty winds at some of the more exposed locations
like Ironwood. Temps are still aoa 60 at some of the warmer
locations, mainly in the downslope locations near Lk Sup. Some
showers/a few TS are occurring over nw MN ahead of the slowly aprchg
cold fnt and ahead of another shrtwv moving enewd into the nrn
Plains, but the fairly dry/capped environment depicted on the 00Z
INL raob is limiting the coverage of these showers.
Main fcst concerns in the short term wl be timing of aprchg cold fnt
and accompanying pops.
Today...Although some sharper deep lyr qvector cnvgc ahead of the
shrtwv now moving thru the nrn Plains is fcst to arrive by 18Z over
the nw cwa and the sfc cold fnt is fcst to reach wrn Lk Sup in the
21-24Z time frame, almost all the models show the persistent sw flow
wl maintain a sufficiently dry/capped environment in the pre frontal
environment to hold pcpn off thru early this evng over the entire
land cwa except Isle Royale. With a good deal of sunshine per fcst
sdngs and h85 temps peaking arnd 16C, expect max temps to reach aoa
80 in the downslope areas near Lk Sup. The coolest temps holding in
the lo 70s wl be downwind of Lk MI. This daytime heating/mixing wl
cause some gusty winds. The gusty winds wl probably diminish by
later in the aftn over the w as the pres gradient begins to weaken
there.
Tngt...Since the incoming sfc cold fnt wl be parallel to the wsw
flow aloft, this bndry is fcst to move only slowly to the se and
probably not reach se Upr MI until closer to 12Z Tue. Considering
the dry, capped pre frontal environment, the models sug most of the
accompanying showers wl occur right along and behind the fnt.
Another shrtwv embedded in the wsw flow aloft/area of dpva/sharper
deep lyr qvector cnvgc/upr dvgc are progged to aprch later at ngt,
which may result in more nmrs and perhaps wdsprd showers after 06Z,
especially over the central cwa under band of sharpening h85-7 fgen.
.LONG TERM...(Tuesday through Sunday)
Issued at 328 AM EDT MON SEP 12 2016
A SFC cold front will exit the southeastern CWA Tue afternoon as a
shortwave moves along the front. Models continue to indicate an area
of widespread precip over mainly the southeastern half to third of
the CWA mainly Tue morning. Potential for over a half inch of rain
in favored areas Tue morning on top of Mon night precip. The
location of best shower and thunderstorm coverage/intensity will
depend on the location of the front and shortwave as they interact.
A shortwave will move in from the NW late Tue into early Wed, but
should not produce widespread precip as it will be fighting dry SFC
high pressure moving in from the W. What it will do is drop 850mb
temps to 2-4C, which will be cool enough for some lake effect clouds
and rain showers late Tue into Wed.
Next precip potential is Thu night into Mon as upper level energy is
modeled to move through. Plenty of disagreement on details, so
will stick with consensus blends for now.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday night)
Issued at 122 AM EDT MON SEP 12 2016
The high pres ridge is shifting e as a cold front approaches from
the Northern Plains, but the low-level air mass will remain dry
across the area through the day on Mon, allowing VFR conditions to
continue at KIWD/KCMX/KSAW. As the pres gradient tightens btwn the
exiting high pres ridge and the approaching cold front tonight
stronger sw winds just off the surface above the noctural radiational
inversion will result in LLWS at KCMX/KSAW tonight. Expected gusty sw
winds at IWD through the night will eliminate the need for LLWS
mention there. The approach of showers along the front Mon evening
will allow conditions to drop down to MVFR and could drop to IFR at
IWD as winds begin to shift nw/onshore in the wake of the frontal
passage.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 403 AM EDT MON SEP 12 2016
SW winds up to 25kts today, and even to 30kts this morning at some
of the hier platforms, will diminish and shift to the n tonight into
Tue behind a cold frontal passage. These winds are not expected to
exceed 20-25kts. Arrival of trailing hi pres on Wed will result in
winds diminishing to under 15kt. After the hi moves to e late this
week, winds will back to the ssw but remain under 20kts on Thu/Fri.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...KC
LONG TERM...Titus
AVIATION...Voss
MARINE...KC
Area Forecast Discussion
National Weather Service Omaha/Valley NE
354 AM CDT MON SEP 12 2016
.SHORT TERM...(today through Wednesday)
Issued at 241 AM CDT MON SEP 12 2016
Main forecast challenge is thunderstorm chances with potential
for severe storms, mainly across southeast Nebraska and southwest
Iowa.
00z upper air analysis showed a broad area of +50 meter height
falls at 500mb over the Pacific Northwest near the base of a
splitting mid-upper level trough. On the back side of this was a
90kt 300mb jet segment. Another small circulation not sampled well
by upper air analysis but well defined off water vapor imagery was currently
over southern Nevada and heading toward the Four Corners region.
Otherwise, modest west/southwesterly mid level flow continues over
the nation`s mid section with a few noticeable embedded shortwaves
sliding across the central High Plains. Early morning surface
analysis shows a well defined cold front extending from low
pressure over Ontario, southeastward through central South Dakota
and into southeastern Wyoming.
As the above mentioned upper trough continues to dig south across
the Pacific coastline, the surface front will slowly push
southeastward through the forecast area. By 15Z, the cold front is
forecast to extend from the arrowhead of Minnesota to northeast
Nebraska and into western Kansas. This boundary will begin to
slow by 18z which will certainly complicate high temperatures.
Ahead of the boundary, daytime surface heating and rapidly increasing
low level moist advection should contribute to MLCAPE values
around 2000 J/KG by late afternoon, however, a fair amount of CIN
will need to be overcome for convective initiation to occur.
Thoughts are that a weak shortwave trough moving in from the
southwest early this evening will weaken the CAP allowing for
rapid late afternoon/early evening thunderstorm
initiation...generally around the 23Z-00z time frame. In fact,
most recent runs of both the operational and experimental HRRR
show little to no activity ahead of the front until 23z or even
slightly thereafter. SWODY1 has added a Slight Risk along and
ahead of the front for a narrow window of time.
Otherwise...scattered showers and isolated weak thunderstorms will
likely persist behind the front throughout the day.
This cold front should exit the forecast area sometime Tuesday
morning with the possibility of post frontal showers lingering
through a good portion of Tuesday as weak impulses continue to
slide through southwesterly mid level flow. A much cooler airmass
will drop out of the Dakotas with highs on Tuesday around 10-15
degrees below normal.
Mainly dry conditions are expected Wednesday as mid level heights
rise under a weak upper ridge and surface high pressure skirts
the region.
.LONG TERM...(Wednesday night through Sunday)
Issued at 241 AM CDT MON SEP 12 2016
A pronounced mid-upper level low over the Great Basin will open
and drift east into the Rockies through the work week with the
trough axis moving through the Central Plains by the weekend.
Ahead of it, synoptic scale lift along with strong warm air
advection regime should allow widespread precipitation into the
end of the work week. Once the trough axis passes early Saturday,
cooler/dry high pressure will build overhead for the remainder of
the weekend.
&&
.AVIATION...(06Z TAFS for KOFK...KLNK and KOMA.)
Issued at 1138 PM CDT SUN SEP 11 2016
VFR conditions through the period. Southerly winds around 12 knots
initially, with non convective LLWS. Winds around 2000` range
40-45 knots, but diminishes by 13-15z. Thunderstorm chances
increase toward the end of the TAF period, by 22-03z at KOFK, and
00-06z at KOMA/KLNK.
&&
.OAX Watches/Warnings/Advisories...
NE...None.
IA...None.
&&
$$
SHORT TERM...Kern
LONG TERM...Kern
AVIATION...DeWald
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
312 AM CDT MON SEP 12 2016
.SHORT TERM...(Today and Tonight)
Issued at 312 AM CDT MON SEP 12 2016
Sfc trough axis and cold front this morning stretches from
southeast CO through the western high plains. Southerly winds
across the western two thirds of the state remained gusty
overnight at 10 to 15 mph sustained, holding lows this morning to
the middle and upper 60s towards Concordia and Manhattan. Over far
eastern KS, light easterly winds under the sfc inversion layer
will continue to cool temps to the lower 60s. For today, southerly
winds increase over northeast KS as the sfc trough gradually
tightens eastward ahead of an approaching shortwave trough. Wind
speeds at 10 to 20 mph sustained with gusts to near 30 mph are
likely, advecting warmer temps from the southwest, raising highs
into the middle and upper 80s.
Sfc instability is progged to increase ahead of the approaching cold
front to near 3000 J/KG of Sfc based CAPE seen on the NAM and HRRR.
Mixed layer CIN erodes after 22Z over far north central areas where
scattered convection may develop in vicinity of the boundary,
however convergence with the boundary is fairly weak. 0-6 KM bulk
shear near 30 kts is sufficient to sustain a few rotating updrafts
if this scenario comes to be. Convection that develops initially in
the evening hours may become severe with hail and damaging winds the
main hazards for areas mainly near and north of the highway 36
corridor. Main uncertainty for the overnight period is if
additional, more widespread showers and thunderstorms form further
southwest, propagating east into the area after midnight.
The latest GFS and ECMWF would suggest this scenario due to a
stronger mid level wave stretching further southwest into KS. The
NAM, GEM, and to some extent the HRRR would suggest the lead wave
focuses further north over NE, exiting overnight and keeping most of
the precipitation north of Interstate 70. Based on the uncertainty,
I did back off on pops overnight with the exception of far northern
KS. It is possible that if convection forms over central KS, it
should impact most of northeast KS by Tuesday morning, but at this
point confidence was not high enough to go likely in precip.
Severe weather is not expected during the overnight period.
.LONG TERM...(Tuesday through Sunday)
Issued at 312 AM CDT MON SEP 12 2016
The 00Z models remain consistent in pushing the cold front
through the forecast area on Tuesday. The lift from the front is
expected to be enough for scattered showers and storms to form
through Tuesday night even as forcing remains somewhat subtle. The
NAM shows a vort max moving through the southwest flow aloft on
Tuesday, but the ECMWF and GFS solutions are less obvious with the
forcing. Because of this have kept POPs at 50 percent thinking
precip may tend to be more scattered in nature. There should be
quite a gradient in temps Tuesday ranging from the mid 80s across
east central KS expecting some insolation and a lack of cold air
advection until late in the day, to the upper 60s over north
central KS thinking skies with remain cloudy with a north wind
advecting in some cooler air.
Wednesday looks to be the day with the lowest chances for precip
as shortwave ridging moves overhead while the surface ridge moves
over the area. Because of this only have some slight chance POPs
in the forecast. Additionally lapse rates do not appear to be
very steep, even for an elevated parcel. So with a lack of
instability, have removed the mention of thunderstorms for
Wednesday. Cloud cover through the day is expected to limit the
diurnal range of temps with lows expected to start out in the mid
50s to lower 60s and highs only reaching the lower to mid 70s.
For Thursday through Friday night, models show the upper trough
from the southwest moving across the plains and bringing a Pacific
airmass into the plains. Since the earlier high pressure system
generally moves across the upper midwest, there should be plenty
of moisture across the central plains as the system moves out from
the Rockies. Therefore have likely POPs for Thursday through
Friday as the better forcing from the upper trough interacts with
the moisture. Temps appear to remain mild with lows in the 50s and
lower 60s while highs stay in the 70s.
For Saturday and Sunday, the better flow is progged to remain
north of the forecast area with weak high pressure over the
centralplains. Since there isn`t any strong signal of forcing
for precip and models show a dryer airmass through the weekend,
have a dry forecast. There doesn`t appear to be a big change in
airmass over the weekend either so the temp forecast is one of
persistence with highs in the 70s and lows in the 50s.
&&
.AVIATION...(For the 06Z TAFS through 06Z Monday Night)
Issued at 1135 PM CDT SUN SEP 11 2016
LLWS overnight is initial concern. VFR for remainder of the
period, could start to see some vcts toward MHK at tail end of the
forecast.
&&
.TOP Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...Prieto
LONG TERM...Wolters
AVIATION...67
Area Forecast Discussion
National Weather Service Marquette MI
738 AM EDT MON SEP 12 2016
.SHORT TERM...(Today and tonight)
Issued at 403 AM EDT MON SEP 12 2016
00Z raobs/latest wv imagery and RAP analysis show some lo amplitude
upr rdging centered over the wrn Great Lks downstream of a deepening
upr trof over the Pac NW coincident with a shrtwv digging into that
area. An acyc sw flow arnd hi pres over the Mid Atlantic states/dry
capped environment depicted on the local 00Z raobs are bringing
tranquil wx to the cwa this mrng, with just some mainly hi clds
spreading ovhd. The tightening pres gradient btwn the departing hi
pres and a cold fnt stretching fm nw Ontario into the nrn Plains
attendant to a shrtwv lifting enewd thru scentral Canada has
resulted in some gusty winds at some of the more exposed locations
like Ironwood. Temps are still aoa 60 at some of the warmer
locations, mainly in the downslope locations near Lk Sup. Some
showers/a few TS are occurring over nw MN ahead of the slowly aprchg
cold fnt and ahead of another shrtwv moving enewd into the nrn
Plains, but the fairly dry/capped environment depicted on the 00Z
INL raob is limiting the coverage of these showers.
Main fcst concerns in the short term wl be timing of aprchg cold fnt
and accompanying pops.
Today...Although some sharper deep lyr qvector cnvgc ahead of the
shrtwv now moving thru the nrn Plains is fcst to arrive by 18Z over
the nw cwa and the sfc cold fnt is fcst to reach wrn Lk Sup in the
21-24Z time frame, almost all the models show the persistent sw flow
wl maintain a sufficiently dry/capped environment in the pre frontal
environment to hold pcpn off thru early this evng over the entire
land cwa except Isle Royale. With a good deal of sunshine per fcst
sdngs and h85 temps peaking arnd 16C, expect max temps to reach aoa
80 in the downslope areas near Lk Sup. The coolest temps holding in
the lo 70s wl be downwind of Lk MI. This daytime heating/mixing wl
cause some gusty winds. The gusty winds wl probably diminish by
later in the aftn over the w as the pres gradient begins to weaken
there.
Tngt...Since the incoming sfc cold fnt wl be parallel to the wsw
flow aloft, this bndry is fcst to move only slowly to the se and
probably not reach se Upr MI until closer to 12Z Tue. Considering
the dry, capped pre frontal environment, the models sug most of the
accompanying showers wl occur right along and behind the fnt.
Another shrtwv embedded in the wsw flow aloft/area of dpva/sharper
deep lyr qvector cnvgc/upr dvgc are progged to aprch later at ngt,
which may result in more nmrs and perhaps wdsprd showers after 06Z,
especially over the central cwa under band of sharpening h85-7 fgen.
.LONG TERM...(Tuesday through Sunday)
Issued at 328 AM EDT MON SEP 12 2016
A SFC cold front will exit the southeastern CWA Tue afternoon as a
shortwave moves along the front. Models continue to indicate an area
of widespread precip over mainly the southeastern half to third of
the CWA mainly Tue morning. Potential for over a half inch of rain
in favored areas Tue morning on top of Mon night precip. The
location of best shower and thunderstorm coverage/intensity will
depend on the location of the front and shortwave as they interact.
A shortwave will move in from the NW late Tue into early Wed, but
should not produce widespread precip as it will be fighting dry SFC
high pressure moving in from the W. What it will do is drop 850mb
temps to 2-4C, which will be cool enough for some lake effect clouds
and rain showers late Tue into Wed.
Next precip potential is Thu night into Mon as upper level energy is
modeled to move through. Plenty of disagreement on details, so
will stick with consensus blends for now.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday morning)
Issued at 738 AM EDT MON SEP 12 2016
A sw flow arnd slowly departing sfc hi pres and ahead of a slowly
apchg cold fnt wl continue to tap dry air thru the day, bringing VFR
conditions to all the TAF sites. Daytime mixing wl cause gusty sw
winds most of the day until the loss of daytime heating and a slowly
weakening pres gradient diminish the gusts. As the cold fnt arrives,
so will some showers along with MVFR cigs and vsbys. Best chc for
IFR cigs will be at IWD, where there wl be a more pronounced upslope
wind component/sufficient llvl moistening.
&&
.MARINE...(For the 4 AM Lake Superior forecast issuance)
Issued at 403 AM EDT MON SEP 12 2016
SW winds up to 25kts today, and even to 30kts this morning at some
of the hier platforms, will diminish and shift to the n tonight into
Tue behind a cold frontal passage. These winds are not expected to
exceed 20-25kts. Arrival of trailing hi pres on Wed will result in
winds diminishing to under 15kt. After the hi moves to e late this
week, winds will back to the ssw but remain under 20kts on Thu/Fri.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...KC
LONG TERM...Titus
AVIATION...KC
MARINE...KC
Area Forecast Discussion
National Weather Service Omaha/Valley NE
615 AM CDT MON SEP 12 2016
.SHORT TERM...(Today through Wednesday)
Issued at 354 AM CDT MON SEP 12 2016
Main forecast challenge is thunderstorm chances with potential
for severe storms, mainly across southeast Nebraska and southwest
Iowa.
00z upper air analysis showed a broad area of +50 meter height
falls at 500mb over the Pacific Northwest near the base of a
splitting mid-upper level trough. On the back side of this was a
90kt 300mb jet segment. Another small circulation not sampled well
by upper air analysis but well defined off water vapor imagery was
currently over southern Nevada and heading toward the Four
Corners region. Otherwise, modest west/southwesterly mid level
flow continues over the nation`s mid section with a few noticeable
embedded shortwaves sliding across the central High Plains. Early
morning surface analysis shows a well defined cold front extending
from low pressure over Ontario, southeastward through central
South Dakota and into southeastern Wyoming.
As the above mentioned upper trough continues to dig south across
the Pacific coastline, the surface front will slowly push
southeastward through the forecast area. By 15Z, the cold front is
forecast to extend from the arrowhead of Minnesota to northeast
Nebraska and into western Kansas. This boundary will begin to
slow by 18z which will certainly complicate high temperatures.
Ahead of the boundary, daytime surface heating and rapidly increasing
low level moist advection should contribute to MLCAPE values
around 2000 J/KG by late afternoon, however, a fair amount of CIN
will need to be overcome for convective initiation to occur.
Thoughts are that a weak shortwave trough moving in from the
southwest early this evening will weaken the CAP allowing for
rapid late afternoon/early evening thunderstorm
initiation...generally around the 23Z-00z time frame. In fact,
most recent runs of both the operational and experimental HRRR
show little to no activity ahead of the front until 23z or even
slightly thereafter. SWODY1 has added a Slight Risk along and
ahead of the front for a narrow window of time.
Otherwise...scattered showers and isolated weak thunderstorms will
likely persist behind the front throughout the day.
This cold front should exit the forecast area sometime Tuesday
morning with the possibility of post frontal showers lingering
through a good portion of Tuesday as weak impulses continue to
slide through southwesterly mid level flow. A much cooler airmass
will drop out of the Dakotas with highs on Tuesday around 10-15
degrees below normal.
Mainly dry conditions are expected Wednesday as mid level heights
rise under a weak upper ridge and surface high pressure skirts
the region.
.LONG TERM...(Wednesday night through Sunday)
Issued at 354 AM CDT MON SEP 12 2016
A pronounced mid-upper level low over the Great Basin will open
and drift east into the Rockies through the work week with the
trough axis moving through the Central Plains by the weekend.
Ahead of it, synoptic scale lift along with strong warm air
advection regime should allow widespread precipitation into the
end of the work week. Once the trough axis passes early Saturday,
cooler/dry high pressure will build overhead for the remainder of
the weekend.
&&
.AVIATION...(12Z TAFS for KOFK...KLNK and KOMA.)
Issued at 615 AM CDT MON SEP 12 2016
Expect VFR conditions and southerly winds into mid afternoon. The
chance for TSRA will increase at KOFK by late afternoon and at
both KOMA and KLNK this evening. MVFR or lower conditions are
possible in the TSRA through the evening. Conditions should
deteriorate later tonight 2 few hours after the passage of a cold
front...with ceilings in the 1000 to 2000 foot range becoming
likely.
&&
.OAX Watches/Warnings/Advisories...
NE...None.
IA...None.
&&
$$
SHORT TERM...Kern
LONG TERM...Kern
AVIATION...Miller
Area Forecast Discussion
National Weather Service Phoenix AZ
852 AM MST MON SEP 12 2016
.SYNOPSIS...
Modest moisture return through southern and central Arizona will
allow the development of isolated to scattered showers and
thunderstorms today. This will especially be the case for higher
terrain locations north and east of Phoenix. More predominant
westerly flow will draw much drier air back into the region
beginning Tuesday and continuing through the week. This will result
in widespread dry weather though with temperatures staying near to
slightly cooler than normal.
&&
.DISCUSSION...
Early morning MCS has moved into eastern Arizona. In its wake,
widespread mid clouds and ACCAS persist across central Arizona.
Latest mesoanalysis shows a tongue of deeper moisture extending
northeastward from Yuma to Phoenix with surface dewpoints generally
in the 60s and low-level mixing ratios in a 10 to 12 g/kg range.
Given the cooler temperatures aloft associated with the broad trough
across the Pacific Northwest, anomalous SBCAPEs will support
additional isolated showers this morning from Maricopa county
eastward.
Latest CAMs still suggest somewhat more organized activity will
develop across eastern Pinal and Gila counties this afternoon,
however the latest runs of the HRRR are not as bullish. Nevertheless,
bulk shear is stronger than normal (albeit unidirectional) and any
storms that develop have the potential to produce brief heavy rain
and strong wind gusts. Minor adjustments to the short-term forecast
were needed to account for some cooler temperatures. Otherwise, the
forecast remains on track.
&&
.PREVIOUS DISCUSSION...
The formerly mentioned Pacific Northwest trough will swing into
cntrl Nevada Tuesday, becoming more neutrally tilted, and temporarily
stall/fill (before lifting out later in the week). Height falls will
continue to spread into SE California and Arizona through Wednesday
allowing temperatures to cool a few more degrees from today. In fact,
best performing guidance indicates Tuesday and/or Wednesday will
result in highs across the entire forecast area remaining below the
100F threshold (first time this has happened in many months) - truly
a harbinger of upcoming autumn weather. Otherwise despite jet energy
through the region and moisture not completely scoured east, a vast
majority of model output fails to develop storms during the afternoon
hours (even at the preferred higher elevation locations). Kept some
lower end slight chance POPs valid for southern Gila County with dry
air still holding solid over the western half of the CWA.
Very little forecast uncertainty for the latter half of the week as
one trough lifts northeast into the plains, yet weaknesses in the
height fields off the California coast allows for renewed energy to
fill in its place. This will reinforce stronger deep westerly flow
through the SW Conus pushing appreciable moisture east of the
Continental Divide and well into central Mexico. H5 heights will dip
into a 582dm range keeping temperatures in a slightly below average
range. In fact, with cooler daytime temperatures, a very dry
airmass, and clear skies, overnight lows will plummet into the 60s
for many lower elevation locations (and even some 50s in the coolest
communities). Another sign that desert southwest autumn weather is
not that far away.
&&
.AVIATION...
South-Central Arizona Including KPHX, KIWA, and KSDL:
A weather disturbance moving across AZ today has already produced
isolated early morning shower/tstms over Phoenix area. Anticipate
activity to be isolated enough that VCTS should suffice for KPHX. Anticipate
the activity to start trending down from west to east after 14Z.
Otherwise...SCT-BKN decks at FL100-120 and BKN-OVC at FL150
decreasing aft 15Z. Anticipate redevelopment of storms aft
21Z...mainly Pinal and Gila Counties...but affecting portions of east
Valley. Thus VCTS in the TAFs. Outflows could reach the airfields
(even if without direct hit from Cb cloud) at some point this
afternoon and early evening but confidence too low to reflect in
TAFs. Surface winds will fluctuate between southwest and southeast
this morning before trending southwesterly this afternoon.
Southeast California/Southwest Arizona including KIPL and KBLH:
A weather disturbance moving from the Mohave desert into Arizona
this morning will produce SCT-BKN clouds east of the Lower Colorado
River Valley at FL100-120 til 15Z before decreasing. Surface winds
will favor southerly directions this afternoon and evening (westerly
over the Imperial Valley) with gusts of 25-30 kts.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Wednesday through Sunday...
A low pressure system passing through the West will keep temperatures
slightly below normal Wednesday and Thursday but will import drier
air. This will cause a downtrend in humidities with minimum readings dipping
below 10 percent most deserts by Thursday and overnight recovery
dropping to only fair. Storm chances depart from the forecast area as
well. Anticipate a little bit of warming Friday through Sunday with
some improvement in humidities by Sunday. There will be minor
afternoon/evening breezes but otherwise no strong wind events.
&&
.SPOTTER INFORMATION STATEMENT...
Amateur radio Skywarn net activation is not expected at this time.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Hirsch
PREVIOUS DISCUSSION...MO
AVIATION...AJ
FIRE WEATHER...AJ
Area Forecast Discussion
National Weather Service Raleigh NC
930 AM EDT MON SEP 12 2016
.SYNOPSIS...
A cold front will stall south of our region today as high pressure
builds south through the Middle Atlantic states. This high pressure
will linger into mid-week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 930 AM Monday...
An elongated H5 vorticity shear axis atop a stalling frontal zonal
extending across the south coast of NC and upstate SC will continue
to support isolated to widely scattered showers and thunderstorms
across the far southern tier counties this afternoon and into the
early evening. PoPs will be maximized during peak afternoon heating
and resultant weak destabilization as MLCAPE values are forecast to
peak between 500 to 750 J/Kg, with BL stabilization from loss of
daytime heating leading to quick dissipation of convection.
For the other 80 percent of central NC including the Triad,
Triangle, the Piedmont, most of the Sandhills and northern Coastal
Plain, it will be cooler and less humid in the wake of last night`s
frontal passage as high pressure builds across the Mid-Atlantic
States. The most difficult aspect with today`s forecast is the
evolution of the 1 to 3kft stratus cloud deck that has developed in
response to shallow isentropic lift in the 300K layer in an arc
extending from the central/southern coastal plain counties back into
the northern foothills. The RAP and HRRR forecast soundings suggest
some of these low clouds could linger through midday, resulting in a
slow warm up across the southern counties. Will monitor satellite
trends today and adjust temps as necessary. Highs ranging from lower
80s northwest to mid-upper 80s near the SC border. Lows tonight in
the lower 60s north to upper 60s south.
&&
.SHORT TERM /TUESDAY and TUESDAY NIGHT/...
As of 250 AM Monday...
Other than a slight chance of mainly afternoon and early evening showers and
thunderstorms in the far SE Coastal Plain, dry conditions are expected as
high pressure (near 1025 mb) will extend from southern New England southwest
across VA and NC. The ridge axis should be over NC with plenty of sinking air.
The only exception will be in the far SE where the easterly flow and proximity
of the "washed out" boundary may aid in a low POP for afternoon and early evening
showers. Highs will again be mostly in the 80s with the NE flow at the surface.
Expect mostly clear to partly cloudy skies Tuesday night except mostly cloudy in
in the SE. Lows 55-60 northern Piedmont ranging into the mid 60s SE.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
As of 315 AM Monday...
Expect above normal temperatures (mid/upper 80s) by mid-week, in
advance of a progressive upper level trough /attendant cold
front/tracking eastward through the Great Lakes into New England.
The aforementioned cold front is expected to weaken and stall (in a
west-east orientation) over VA/WV on Thursday as the parent upper
wave /sfc low/ progress rapidly offshore the New England coast. In
the wake of the aforementioned wave, synoptic subsidence and surface
pressure rises over the OH valley and Mid-Atlantic will push
the stalled frontal zone S/SW into central NC as a backdoor cold
front on Friday. With this in mind, expect near normal temps by the
end of the work week. Isolated convection will be possible with the
backdoor front late Thu/Fri, with coverage limited by weak upper
forcing (similar to the recent backdoor fropa). Temps are expected
to rise slightly above normal again this weekend as high pressure
shifts offshore and a southerly return flow develops in advance
of the next cold front approaching from the west on Sunday. Chances
for convection along/ahead of the front may be best in the N/NW
piedmont, closer to upper level forcing attendant a shortwave
progged to track slowly east across the Mid-Atlantic. -Vincent
&&
.AVIATION /12Z MONDAY THROUGH FRIDAY/...
As of 700 AM Monday...
Winds will shift to the NE early in the period across the region as
a cold front settles south into South Carolina this morning. High
pressure will build in from the NE tonight through Tuesday.
Generally VFR conditions are expected, except for a period of
stratus this morning between 08z-13z (KFAY and KRWI). Another period of
late night and early morning stratus will be likely, especially
at KRWI and KFAY again tonight.
Looking further ahead... Generally VFR conditions are expected
Tuesday through Thursday.
&&
.RAH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Badgett
NEAR TERM...CBL
SHORT TERM...Badgett
LONG TERM...Vincent
AVIATION...Badgett
...Update to aviation forecast discussion...
.SHORT TERM...(Today and Tonight)
Issued at 312 AM CDT MON SEP 12 2016
Sfc trough axis and cold front this morning stretches from
southeast CO through the western high plains. Southerly winds
across the western two thirds of the state remained gusty
overnight at 10 to 15 mph sustained, holding lows this morning to
the middle and upper 60s towards Concordia and Manhattan. Over far
eastern KS, light easterly winds under the sfc inversion layer
will continue to cool temps to the lower 60s. For today, southerly
winds increase over northeast KS as the sfc trough gradually
tightens eastward ahead of an approaching shortwave trough. Wind
speeds at 10 to 20 mph sustained with gusts to near 30 mph are
likely, advecting warmer temps from the southwest, raising highs
into the middle and upper 80s.
Sfc instability is progged to increase ahead of the approaching cold
front to near 3000 J/KG of Sfc based CAPE seen on the NAM and HRRR.
Mixed layer CIN erodes after 22Z over far north central areas where
scattered convection may develop in vicinity of the boundary,
however convergence with the boundary is fairly weak. 0-6 KM bulk
shear near 30 kts is sufficient to sustain a few rotating updrafts
if this scenario comes to be. Convection that develops initially in
the evening hours may become severe with hail and damaging winds the
main hazards for areas mainly near and north of the highway 36
corridor. Main uncertainty for the overnight period is if
additional, more widespread showers and thunderstorms form further
southwest, propagating east into the area after midnight.
The latest GFS and ECMWF would suggest this scenario due to a
stronger mid level wave stretching further southwest into KS. The
NAM, GEM, and to some extent the HRRR would suggest the lead wave
focuses further north over NE, exiting overnight and keeping most of
the precipitation north of Interstate 70. Based on the uncertainty,
I did back off on pops overnight with the exception of far northern
KS. It is possible that if convection forms over central KS, it
should impact most of northeast KS by Tuesday morning, but at this
point confidence was not high enough to go likely in precip.
Severe weather is not expected during the overnight period.
.LONG TERM...(Tuesday through Sunday)
Issued at 312 AM CDT MON SEP 12 2016
The 00Z models remain consistent in pushing the cold front
through the forecast area on Tuesday. The lift from the front is
expected to be enough for scattered showers and storms to form
through Tuesday night even as forcing remains somewhat subtle. The
NAM shows a vort max moving through the southwest flow aloft on
Tuesday, but the ECMWF and GFS solutions are less obvious with the
forcing. Because of this have kept POPs at 50 percent thinking
precip may tend to be more scattered in nature. There should be
quite a gradient in temps Tuesday ranging from the mid 80s across
east central KS expecting some insolation and a lack of cold air
advection until late in the day, to the upper 60s over north
central KS thinking skies with remain cloudy with a north wind
advecting in some cooler air.
Wednesday looks to be the day with the lowest chances for precip
as shortwave ridging moves overhead while the surface ridge moves
over the area. Because of this only have some slight chance POPs
in the forecast. Additionally lapse rates do not appear to be
very steep, even for an elevated parcel. So with a lack of
instability, have removed the mention of thunderstorms for
Wednesday. Cloud cover through the day is expected to limit the
diurnal range of temps with lows expected to start out in the mid
50s to lower 60s and highs only reaching the lower to mid 70s.
For Thursday through Friday night, models show the upper trough
from the southwest moving across the plains and bringing a Pacific
airmass into the plains. Since the earlier high pressure system
generally moves across the upper midwest, there should be plenty
of moisture across the central plains as the system moves out from
the Rockies. Therefore have likely POPs for Thursday through
Friday as the better forcing from the upper trough interacts with
the moisture. Temps appear to remain mild with lows in the 50s and
lower 60s while highs stay in the 70s.
For Saturday and Sunday, the better flow is progged to remain
north of the forecast area with weak high pressure over the
centralplains. Since there isn`t any strong signal of forcing
for precip and models show a dryer airmass through the weekend,
have a dry forecast. There doesn`t appear to be a big change in
airmass over the weekend either so the temp forecast is one of
persistence with highs in the 70s and lows in the 50s.
&&
.AVIATION...(For the 12Z TAFS through 12Z Tuesday Morning)
Issued at 602 AM CDT MON SEP 12 2016
VFR continues through forecast period. LLWS still observed at 300
feet with light winds at KTOP/KFOE, however should increase to
near 10 kts by 15Z with gusty south winds prevailing through the
afternoon. Strongest gusts at KMHK and KFOE may peak in the 25 to
30 kt range. High clouds increase this evening with the cold front
approaching. All short term guidance is similar in holding off
TSRA to the northwest of terminals. KMHK may see VCTS aft 09Z
however this will depend on the coverage of thunder. LLWS is once
again likely aft 01Z with backing southerly sfc winds becoming
light. MVFR ceilings may also be possible just after 12Z Tuesday.
&&
.TOP Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...Prieto
LONG TERM...Wolters
AVIATION...Prieto
Area Forecast Discussion
National Weather Service Bismarck ND
323 PM CDT Mon Sep 12 2016
.SHORT TERM...(Today through Wednesday)
Issued at 323 PM CDT Mon Sep 12 2016
Forecast highlights in the short term period will be frost and
freeze headlines for tonight west, possibly needed again for
Wednesday morning north central.
Currently, west-southwest/cyclonic flow aloft as a long wave
trough moves slowly east across the region. At the surface, strong
high pressure centered over far southeast Alberta/southwest
Saskatchewan moving slowly east-southeast into the Northern High
Plains. Embedded energy and cold temperatures aloft contributing
to extensive cloud cover across the Northern Plains, with a few
breaks here and there.
Will maintain frost/freeze headlines as is with this forecast
issuance for northwest and west central ND late tonight into
Tuesday morning. High res models remain in agreement with upper
20s to low 30s far northwest (Williams/Divide) where the center of
the sfc high will be located at 12Z. This should allow
temperatures there to drop fairly rapidly as winds taper off and
the sky clears. Sfc Tds 28-32F shown over all of western ND and
into the north central by both the RAP and HRRR, with frost a
concern for all but the southwest then east into central areas of
the state where cloud cover and/or wind should keep temps above
35F.
High pressure moves over the entire state for Tuesday. Beautiful
fall-like day with a sunny sky, light winds, and temperatures
extremely comfortable in the mid to upper 50s.
For Tuesday night, guidance indicates mid 30s over far north
central ND into the Turtle Mountains. Possible we may need
frost/freeze headlines there but will have to see how Tds pan out
in addition to winds which may be a bit stronger Wed morning with
southerly return flow increasing across the Dakotas. Wednesday
remains dry with temperatures moderating into the mid 60s and
lower 70s.
.LONG TERM...(Wednesday night through Monday)
Issued at 323 PM CDT Mon Sep 12 2016
An ejecting upper level low from the Intermountain West will
shift northeast toward ND beginning Wednesday night, lifting
through the region Thursday night. This feature will bring
increasing chances for showers and thunderstorms into Friday.
Narrow band of instability with MUCAPE forecast in the 1500-2500
J/kg range Thursday into Thursday evening with 0-6km shear
25-35KTs along with plenty of forcing mechanisms with the
approach of the upper low and an associated surface trough over
the central Dakotas. Appears to be a fairly decent setup for
strong thunderstorms Thursday aft/eve and will be interesting to
see what outlook SPC puts the region in with their Day 3 update
later tonight.
Upper level ridging for the weekend with warming and drying
conditions. Highs this weekend will fall in the 70s to near 80.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 323 PM CDT Mon Sep 12 2016
A period of mvfr cigs expected at KISN/KDIK/KMOT this afternoon
before cigs lift to low vfr by around 20z. Elsewhere, sct to bkn
vfr clouds at or above 3500ft agl through 02z Tuesday. Thereafter,
expect sct low vfr cloud clouds. KJMS could see a period of mvfr
cigs after 09z Tuesday, but confidence low at this time, thus
will just mention a sct layer at 2500ft agl.
&&
.BIS WATCHES/WARNINGS/ADVISORIES...
Frost Advisory from midnight CDT /11 PM MDT/ tonight to 9 AM CDT
/8 AM MDT/ Tuesday for NDZ002-010-017-018-031>033.
Freeze Warning from midnight tonight to 9 AM CDT Tuesday for
NDZ001-009.
&&
$$
SHORT TERM...NH
LONG TERM...NH
AVIATION...KS
Area Forecast Discussion
National Weather Service Quad Cities IA IL
255 PM CDT MON SEP 12 2016
.SYNOPSIS...
Issued at 255 PM CDT Mon Sep 12 2016
High pressure remains entrenched across the area this afternoon
as deep diurnal mixing lead to highs in the low to mid 80s and
winds gusting to around 25 knots in some places. This will
continue for the next couple of hours before the flow turns
southwest and additional moisture pools into the area ahead of a
cold front that will serve as the main weather producer in the
short term.
&&
.SHORT TERM...(This Evening through Tuesday)
ISSUED AT 255 PM CDT Mon Sep 12 2016
Main forecast concern are the chances for showers and
thunderstorms with the cold frontal passage tomorrow across the
area. Guidance has continued slowing the progression of the front
as previous shifts have noted.
H5 leading wave is expected to pass mainly north of the CWA
tonight. The best chances for rain and even isolated thunderstorms
will be with this wave across the north. Far NW zones will see
likely showers with possibly embedded thunder. The HRRR is the
most aggressive in terms of convection breaking out in close
vicinity of the H5 wave. Do not think that this will affect the
area and will likely stay north. Some of the hires guidance
suggests that the precip will weaken near sunrise and actually
miss most the area. H85 jet weakens during this time as well, so
it is likely that the chances for rain will diminish across the
area.
Later development of showers looks possible across the area on
Tuesday with the fropa. ARW and NMM core CAMs have some light
showers across the area near 21z tomorrow. At this time have
maintained current chc pops for Tuesday. Overall threat for
thunderstorms will be low, so isolated T will be maintained.
.LONG TERM...(Tuesday Night through Monday)
ISSUED AT 255 PM CDT Mon Sep 12 2016
The rain with embedded thunderstorms will slowly end from northwest
to southeast Tuesday night as the front pushes south of the area.
The better rain chances appear to be across the southern half of the
area where the better forcing exists.
On Wednesday, lingering showers will end during the morning across
the south third of the area. Temperatures are expected to average
below normal due to the clouds.
Quiet and dry conditions will be seen across the area Wednesday
night as high pressure moves through the Midwest.
Clouds will be on the increase Thursday as the high moves into the
eastern Great Lakes and moisture moves back north. Most of the area
will remain dry Thursday with the exception of the far west and
southwest areas during the afternoon.
Thursday night on...
Thursday night moisture moves back into the area. The first of
several upper level disturbances will move into the area allowing
rain with embedded thunderstorms to develop from west to east. Based
on moisture flow and forcing, the better rain chances look to be
across the western half of the area.
Friday/Friday night another upper level disturbance moves through
the area. Rain with embedded thunderstorms should be fairly
widespread on Friday with rain slowly ending from west to east
Friday night.
Starting Saturday disagreements among the models develop. Some
models indicate a third upper level disturbance will move through
the area on the heels of the second disturbance helping to prolong
the rain. Other solutions start pushing a new high pressure into the
area with dry conditions. As a result, the model consensus has
slight chance to chance pops Saturday with the higher pops over the
northeast half of the area.
Saturday night there may or may not be lingering showers over the
northeast third of the area. Everything depends upon how quickly the
upper level disturbance exits the area.
On Sunday there is a weak upper level disturbance moving through in
the flow aloft. Moisture availability is questionable but some
isolated showers/sprinkles may develop during the afternoon east of
the Mississippi and north of I-80.
Sunday night/Monday the model consensus has dry conditions for the
area as another high pressure builds into the Midwest.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday Afternoon)
ISSUED AT 1236 PM CDT Mon Sep 12 2016
VFR conditions are expected through the period as high pressure
will dominate the next 12 hours of the aviation period. A cold
front with a wind shift will sag across the state later tonight
into tomorrow warning. Some rain showers and even some
thunderstorms are possible across the northern TAF sites. At this
time confidence in thunder is low, so excluded from forecast. MVFR
and possibly IFR conditions are possible for DBQ and CID, but have
left out as of late.
&&
.DVN Watches/Warnings/Advisories...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...Gibbs
SHORT TERM...Gibbs
LONG TERM...08
AVIATION...Gibbs
Area Forecast Discussion
National Weather Service Grand Forks ND
318 PM CDT MON SEP 12 2016
.SHORT TERM...(This evening through Tuesday)
Issued at 318 PM CDT Mon Sep 12 2016
Cloud cover and temperatures will be the main forecast challenges
for the period.
A few streaks of clearing have developed from southwest to
northeast across the CWA, but plenty of cloud cover over the
region and upstream. The upper level flow becomes more split
tonight with the northern branch shortwave moving into the
Dakotas. RAP has high RH in the 925-850mb layer throughout the
night. A few of the models even have some light rain in the
northeastern counties late tonight as a reinforcing cool front
comes down out of Canada. Not overly excited about showers but
included an isolated mention near BDE during the early morning
hours. Winds will be diminishing after sunset but with the surface
high centered out over western ND we will at least have some
northerly flow continuing overnight. This, along with lingering
clouds and dewpoints in the 40s, should keep us from getting too
cold tonight. Will continue to keep lows mainly in the low to mid
40s although the usual cool spots of the far northwest near
Langdon and near Fosston could see lows dipping into the upper
30s.
Surface high pressure will be centered over the Red River Valley
during the day on Tuesday. There should be some clearing late in
the day but with clouds early and 850mb temps getting close to the
zero C mark, temps will not rise too much during the day.
Have highs mainly in the 50s although the southern Red River
Valley could see some 60s.
.LONG TERM...(Tuesday night through Monday)
Issued at 318 PM CDT Mon Sep 12 2016
First challenge in the long term will be just how cold to go Tuesday
night and the associated frost potential. Surface high pressure will
be centered right over the Red River Valley to start the period and
slowly propagate towards central Minnesota. Skies will quickly clear
from west to east allowing temperatures to drop to the lowest
readings thus far this season. The latest model runs are in very
good agreement with 850 mb temperatures dropping into the lower
single digits. The good news is that the main push of cold advection
begins to die down closer to Wednesday morning. This should
hopefully keep temperatures in the upper 30s but a few sites dipping
a bit lower with the potential for frost is not out of the question.
High pressure will keep conditions dry through Wednesday night with
high temperatures remaining below normal (mid to upper 60s). With
modest southerly winds and clouds moving in, Wednesday night will be
much milder than the previous night with readings around the 50
degree mark.
Next forecast challenge will be the return of precipitation chances
for the second half of the week. As the high finally moves off
towards the lower Great Lakes, an upper low will move through the
northern Rockies and towards the Dakotas. Several impulses will
swing through the forecast area with this feature allowing
precipitation chances to linger to end the work week. Weak upper
level ridging will then return which should provide for a decent
fall weekend with highs back into the 70s.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 1233 PM CDT Mon Sep 12 2016
Some MVFR ceilings are hanging on at KBJI, but those should start
to lift in the next few hours and all TAF sites should be VFR with
mid clouds between 5000-11000 ft. Next question will be how much
of the lower stratus in Canada makes its way down into the
forecast area tonight. The short range models as well as the
SREF show the strongest signal for MVFR ceilings over the
northeast, so included KTVF and KBJI for now and can add in
further west if needed. North northwest winds that are rather
breezy this afternoon will settle down around sunset and should
stay below 12 kts.
&&
.FGF Watches/Warnings/Advisories...
ND...None.
MN...None.
&&
$$
SHORT TERM...JR
LONG TERM...Lee
AVIATION...JR
Forecast discussion for routine afternoon forecast issuance
.SHORT TERM...Tonight and Tuesday
Issued at 226 PM CDT Mon Sep 12 2016
The latest RAP analysis and satellite/radar imagery show the central
and eastern parts of Wisconsin located between high pressure
centered over the east coast and a cold front moving across
Minnesota. Mostly clear conditions are prevailing ahead of the
front thanks to very dry mid-level air as depicted on 12z area
soundings. The front is also largely inactive, except for some
shower activity over northern Minnesota, and some scattered storms
moving across southeast South Dakota. Some storms may fire along
the front later this afternoon, but there is considerable inhibition
and any storms should remain upstream of the region prior to 7 pm
anyhow. As the the front moves across the forecast area,
precipitation timing and coverage are the main forecast concerns.
Tonight...The cold front will slowly move east across western WI
during the evening and far northeast/central WI overnight. The 12z
models have again slowed down the front slightly. With upper level
support arriving from the southwest via a weak shortwave and
increasing pwats to around 1.5 inches, should see precipitation
gradually become more widespread through the night. Though chances
of thunderstorms will be present along the front, appears the best
chances will occur late in the evening and early overnight over
central and north-central WI. ML capes of 500-700 j/kg, MU capes
over 1000 j/kg, and steep mid-level lapse rates suggest that
isolated strong storms will be possible, but the threat of severe
storms is low. As instability diminishes overnight, should only see
an isolated thunderstorm even with better forcing arriving. Temps
should remain mild in the evening due to the southerly winds, and
then fall into the mid 50s to low 60s as the rain arrives late.
Tuesday...The front will continue to pass across central and
northeast WI during the morning before exiting. With shortwave
energy still passing overhead and ample mid-level fgen just behind
the front, should see widespread rain showers continue for much of
the morning before they exit east during the afternoon. Some
clearing may try to work into central WI by late in the afternoon,
but expecting a mostly cloudy or cloudy day to prevail. Temps
cooling down into the low 60s north to near 70 southeast.
.LONG TERM...Tuesday Night Through Monday
Issued at 226 PM CDT Mon Sep 12 2016
Primary weather systems during this period will be a departing
upper trough Tuesday night, and then remnants of the western
states upper trough with frontal system lifting over the area
late in the week and into this weekend.
Trends with the departure timing of the upper trough Tuesday
night continues to be slower along with the RRQ region of the
upper jet passing through. The surface front is progged to be well
southeast of the area by Tuesday night, but the mentioned
dynamics may continue to support light shower activity well into
tuesday night while the 850 baroclinic zone drops south.
Eventually drier boundary level will end any lingering shower
activity.
Surface high pressure and an upper level ridge drifts over the
area Wednesday into Thursday for a dry forecast with cooler than
normal temperatures for Wednesday. Mesoscale Lake Michigan clouds
may become an issue while the high pressure system is drifting
over. Onshore flow combined with some marginal lake induced cape
due to cool boundary layer temperatures over the lake may produce
more clouds. An isolated shower is also possible. Will increase
cloud coverage a little toward the lakeshore as forecast soundings
showing a saturated layer around 1500 feet.
Cool temperatures may produce some overnight lows in the 30s,
especially over the climatological cool spots over the north.
Next chance of precipitation arrives Friday with the next short
wave trough and frontal system. Progs have been fairly consistent
with the timing from Friday into Saturday. Warm air return may
attempt to spread showers and storms back into the western half of
the state late Thursday night.
After a cool start Wednesday, temperatures overall near normal.
&&
.AVIATION...for 18Z TAF Issuance
Issued at 1202 PM CDT Mon Sep 12 2016
Good flying weather albeit with gusty southwest winds this
afternoon. A cold front will then bring periods of rain showers
from late in the evening into Tuesday morning across the taf sites.
Thunder chances look better through midnight over north-central WI
than farther south and east, but not confident in coverage to
include in the forecast. Visibilities and ceilings are expected to
fall with the rainfall late tonight into early Tuesday morning
before improving during the afternoon as the rain pulls out.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
Beach Hazards Statement until 1 AM CDT Tuesday FOR WIZ022-040-
050.
&&
$$
SHORT TERM.....MPC
LONG TERM......TDH
AVIATION.......MPC
Area Forecast Discussion
National Weather Service Miami FL
527 PM EDT MON SEP 12 2016
.DISCUSSION...
.DISCUSSION...
A broad surface trough across the northwest Bahamas continues to have active
convection and still lacks a surface circulation this afternoon.
Recent observations indicate widespread cloudiness and isolated to scattered
thunderstorms across most of the Bahamas chain.
Forecast for tonight...
The global models, the HRRR model and the short range ensemble
model all indicate a broad surface trough across the Palm Beach
county Atlantic waters generally after midnight. An ASCAT pass
earlier today indicated winds across the northeastern periphery
around 20 to 25 knots. The latest short range ensemble model
indicates that there is a chance of winds greater than 25 knots on
the northeastern side but does not indicate any potential for
winds greater than 34 knots. Chances of tropical development
remain low but consult and closely monitor the products from the
National Hurricane Center for any potential for tropical
development. As the trough tracks northwest the strongest winds
should stay to the northeast of the Atlantic waters of South
Florida. So the wind forecast indicates winds in the 15 to 20 knot
range mainly across the off shore Atlantic waters early this
evening and over night. However chances of showers and
thunderstorms are forecast to increase steadily through the early
evening hours and over night as the trough approaches Palm Beach
and Martin counties over night. During this period the most
widespread showers and scattered thunderstorms are expected across
the Atlantic waters east of Palm Beach county, but showers and
thunderstorms will radiate outward from the trough and could
impact the Atlantic coast metro areas over night. While deep
tropical moisture will increase tonight and the potential for
heavy rain will increase, the guidance trends indicate that the
trough will move steadily northwest with showers also moving
steadily in bands, For that reason a flood watch is not being
considered at this time. However, with additional guidance and
radar trends later this evening and over night a watch may be
considered later if need be.
Forecast for Tuesday and Wednesday...
The surface trough is forecast to track northwest over the next
couple of days with a continuous influx of deep moisture and cloudiness
region wide with a chance of showers and thunderstorms. On Tuesday
the trough is forecast to be in central Florida, with surface and
low level southerly flow bringing additional tropical moisture
with widespread showers and scattered thunderstorms possible on
Tuesday. The trough is forecast to be in north Florida Wednesday
but southerly flow and residual moisture will likely linger with a
chance of showers and thunderstorms.
Forecast for late this week...
The global models indicate some relatively drier air moving into
the region across the Bahamas Thursday into Friday but
southeasterly flow and residual moisture should allow for
diurnally driven showers and thunderstorms late in the week.
&&
.MARINE...
As the broad surface trough tracks northwest the strongest winds
should stay to the northeast of the Atlantic waters of South
Florida. However, uncertainties will continue for the marine
forecast over the next couple of days, but more likely for the
Atlantic waters, especially east of Palm Beach county tonight into
Tuesday. As mentioned in the discussion above, the wind forecast
indicates winds in the 15 to 20 knot range mainly across the off
shore Atlantic waters early this evening and over night. However,
a short fused Small Craft advisory may be necessary later this
evening or over night for these waters if the winds are under
forecast.
By mid-week east to southeast winds around 10 knots are forecast
into the upcoming weekend with seas 2 feet or less through this
period.
&&
.BEACH FORECAST...
A slight risk of rip currents is expected across the Gulf coast
beaches through mid-week. Will maintain a moderate risk of rip
currents for tonight through Tuesday for the Atlantic beaches.
However, given the uncertainties with the passage of the trough
tonight through Tuesday, there could be periods for a high risk of
rip currents mainly across Palm Beach county beaches. By mid-week
the Atlantic coast beaches are forecast to have a slight risk.
&&
.PRELIMINARY POINT TEMPS/POPS...
West Palm Beach 77 89 77 89 / 60 70 50 40
Fort Lauderdale 77 89 78 89 / 60 70 40 40
Miami 76 89 78 89 / 60 70 40 40
Naples 77 90 76 90 / 50 70 40 60
&&
.MFL Watches/Warnings/Advisories...
FL...None.
AM...None.
GM...None.
&&
$$
DISCUSSION...60/BD
MARINE...60/BD
BEACH FORECAST...60/BD
Area Forecast Discussion
National Weather Service Marquette MI
439 PM EDT MON SEP 12 2016
.SHORT TERM...(This evening through Tuesday)
Issued at 400 PM EDT MON SEP 12 2016
Water vapor imagery and RAP analysis show a trof with a strong
positive tilt extending from Hudson Bay to the W Coast. Associated
sfc cold front runs from James Bay to sw MN. Front is almost to
western Lake Superior. Ahead of the front, dry/capped environment
per 12z soundings at KMPX/KGRB has prevented any pcpn development
ahead of the front so far. In fact, with the dry prefrontal
environment, there has been abundant sunshine today across the fcst
area, and temps have risen well into the 70s with some locations
reaching 80F. Regional radar imagery has shown very little pcpn in
the vcnty of the cold front so far, but in the last hr, shra/tsra
are beginning to develop along the front in ne MN.
With the approaching mid/upper level trof having a strong positive
tilt, the associated sfc cold front will be slow to move e and se
tonight. Front should reach far western Upper MI around mid evening
and not clear the se fcst area until around mid morning on Tue.
Given the dry/capped prefrontal environment, shra/tsra should be
confined mostly right along and behind the sfc cold front. As
moisture continues to increase in the vcnty of the cold front, sct
shra/tsra should expand slowly along/behind front tonight. Then, it
appears subtle shortwave aiding shra/tsra across portions of
KS/NE/SD will arrive late tonight/Tue morning. With the cold front
moving thru the s central/se fcst area at the time that this subtle
wave arrives very late tonight/Tue morning, an area of more
organized/heavier shra/tsra should spread across that area at that
time. Bulk of model guidance generally supports this scenario. So,
fcst will show a general trend for pops to increase gradually in the
vcnty of the front as it moves across the area, reaching categorical
s central and se. Mucape values are upwards of 1000j/kg or so ahead
of the front, and with deep layer shear 30-40kt, there could be some
strong to perhaps svr storms if any storms do manage to develop
ahead of the front.
The main area of shra should be out of the se fcst area by Tue aftn.
Although cold front continues to move se into Lower MI during the
day, models indicate a nw-se oriented sfc trof setting up, roughly
from just sw of Isle Royale into nw Upper MI in response to another
shortwave that will be moving over northern MN in the aftn. With
850mb temps falling to around 6C, combination of weak deep layer
forcing and low-level trof/convergence should support lake enhanced
shra development in the aftn. If a sharp sfc trof develops, setup
could support waterspout development with some of the shra. Max
temps Tue will be as much as 15-20F lower than today across the w
and n central where highs should be in the low/mid 60s. Temps may
rise close to 70F far s central/se.
.LONG TERM...(Tuesday night through Monday)
Issued at 438 PM EDT MON SEP 12 2016
Models suggest that a progressive pattern will continue to prevail
with the nrn Great Lakes mid/upper level trough sliding to nrn New
England Wednesday as another moves into the nrn Rockies. The trough
will then move to the Upper MS valley by Friday night and to Quebec
by Sunday as a ridge builds over the western Great Lakes.
Tuesday night, expect additional lake enhanced rain as a sfc trough
drops to the south through Upper Michigan. 850 mb temps to around 4C
combined with deep moisture and favorable low level conv along the
trough will support at least sct -shra through the nw half of the
cwa. There may be enough CAPE below 700 mb combined with low level
convergence near the trough for the potential of a few waterspouts
on Lake Superior.
Wednesday, there may be some leftover -shra over the west and north
central which, locations favored by ne low level flow. Otherwise,
lake moisture/clouds will slow any clearing as highs struggle to the
lower 60s north and mid 60s south.
Wednesday night and Thursday, high pressure building over the area
with good radiational cooling will allow temps to drop to the lower
end of guidance with mins in the lower 40s inland and around 50 near
the Great Lakes.
Friday into Saturday, the models, especially the ECMWF have trended
toward a faster and weaker trough moving through the region. With
lingering uncertainty with this feature, only chance pops for
showers were mentioned. There may be enough elevated instability for
isold tsra Friday night.
Sun-Mon, expect dry weather as mid level ridging moves in Sunday.
Although there are larger model differences by Monday, no pcpn is
expected as temps remain near or slightly above normal.
&&
.AVIATION...(For the 18Z TAFS through 18Z Tuesday afternoon)
Issued at 135 PM EDT MON SEP 12 2016
With sw flow ahead of an approaching cold front tapping dry air, VFR
conditions will continue thru the aftn at KIWD/KCMX/KSAW. Winds will
also be gusty, especially at KSAW where gusts will be up to around
25kt. The cold front will slowly move across Upper MI tonight. After
it passes, cigs will fall to mvfr along with an increasing potential
of shra. While thunder is possible, potential is too low right now
to include a mention. At KIWD/KSAW, post frontal winds will be have
a more pronounced upslope component along with more substantial low-
level moistening, and this should result in cigs falling to IFR.
During Tue morning, conditions will remain MVFR at KCMX. At
KIWD/KSAW, conditions will gradually improve to low MVFR.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 400 PM EDT MON SEP 12 2016
Lingering s to sw winds of 20-30kt over eastern Lake Superior will
diminish this evening under weakening pres gradient just ahead of a
cold front that will move across Lake Superior tonight. With passage
of the front, winds will shift northerly, but probably not much
higher than around 20kt thru Tue. Arrival of high pres on Wed will
result in winds diminishing to under 15kt. Winds will become
southerly for Thu/Fri as the high shifts e. While winds should
remain blo 20kt, there may be a period of stronger winds depending
on how tight pres gradient becomes btwn the departing high and the
next approaching low pres. That low will move over the western Great
Lakes region on Sat.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Rolfson
LONG TERM...JLB
AVIATION...Rolfson
MARINE...Rolfson
Area Forecast Discussion
National Weather Service Phoenix AZ
157 PM MST MON SEP 12 2016
.SYNOPSIS...
Modest moisture return through southern and central Arizona will
allow the development of isolated to scattered showers and
thunderstorms through this evening. This will especially be the case
for higher terrain locations north and east of Phoenix. More
predominant westerly flow will draw much drier air back into the
region beginning Tuesday and continuing through the week. This will
result in widespread dry weather though with temperatures staying
near to slightly cooler than normal.
&&
.DISCUSSION...
Isolated strong storms developed earlier this afternoon across
portions of eastern Pinal and Gila counties. The strongest storms exhibited
modest organization with radar signatures even suggesting a BWER and
large hail. Storms have diminished in intensity since then, however
the environment remains conducive for isolated strong storms
containing brief heavy rain, strong wind gusts and small hail
through this evening.
Pocket of deeper moisture still resides across southern Arizona
extending into southern Gila County with low-level mixing ratios in a
10 to 12 g/kg range. Latest AMDAR sounding measured temperatures as
cold as -11C at 500 mb associated with the broad trough across the
Pacific Northwest, which is approaching a record low for the date.
This is contributing to steep mid-level lapse rates and MLCAPE
approaching 1000 J/kg in spots.
Prime areas for redevelopment this afternoon again include Pinal and
southern Gila counties in the vicinity of the deeper moisture,
though latest satellite imagery suggests that isolated storms will be
possible as far west as La Paz/Yuma County, including the Phoenix
area. Latest runs of the HRRR also point to the potential for an
outflow boundary propagating northwestward out of Pinal County and
towards the Phoenix area, which would initiate additional
development. PoPs have been increased in these areas, but still
generally remain less than 10 percent. Consensus amongst the CAMs is
that shower and thunderstorm activity will then subside later this
evening.
&&
.PREVIOUS DISCUSSION...
The formerly mentioned Pacific Northwest trough will swing into
cntrl Nevada Tuesday, becoming more neutrally tilted, and temporarily
stall/fill (before lifting out later in the week). Height falls will
continue to spread into SE California and Arizona through Wednesday
allowing temperatures to cool a few more degrees from today. In fact,
best performing guidance indicates Tuesday and/or Wednesday will
result in highs across the entire forecast area remaining below the
100F threshold (first time this has happened in many months) - truly
a harbinger of upcoming autumn weather. Otherwise despite jet energy
through the region and moisture not completely scoured east, a vast
majority of model output fails to develop storms during the afternoon
hours (even at the preferred higher elevation locations). Kept some
lower end slight chance POPs valid for southern Gila County with dry
air still holding solid over the western half of the CWA.
Very little forecast uncertainty for the latter half of the week as
one trough lifts northeast into the plains, yet weaknesses in the
height fields off the California coast allows for renewed energy to
fill in its place. This will reinforce stronger deep westerly flow
through the SW Conus pushing appreciable moisture east of the
Continental Divide and well into central Mexico. H5 heights will dip
into a 582dm range keeping temperatures in a slightly below average
range. In fact, with cooler daytime temperatures, a very dry
airmass, and clear skies, overnight lows will plummet into the 60s
for many lower elevation locations (and even some 50s in the coolest
communities). Another sign that desert southwest autumn weather is
not that far away.
&&
.AVIATION...
South-Central Arizona Including KPHX, KIWA, and KSDL:
Chances for showers in the Phoenix area terminals remains low
through the afternoon and into the evening. Expect a westerly shift
for the winds during the afternoon. Any storms that do form might be
able to send an outflow towards the terminals. This may help the
diurnal easterly winds take hold a little earlier.
Southeast California/Southwest Arizona including KIPL and KBLH:
Winds will have a more westerly component, especially for KIPL.
However, expect gusty conditions of 25-30 kts through the afternoon
and evening. Otherwise, expect clear skies.
&&
.FIRE WEATHER...
Thursday through Monday...
Temperatures will be near normal but the region should expect drier
air. That means minimum humidities near 10% for the lower deserts
and 20% in the higher elevations through Saturday. There will be
some improvement in humidities by Sunday. No real chance for any
storms, but some afternoon breezes are possible.
&&
.SPOTTER INFORMATION STATEMENT...
Amateur radio Skywarn net activation is not expected at this time.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Hirsch
PREVIOUS DISCUSSION...MO
AVIATION...Deemer
FIRE WEATHER...Deemer
Area Forecast Discussion
National Weather Service Reno NV
234 PM PDT MON SEP 12 2016
.SYNOPSIS...
Much cooler temperatures along with showers and isolated
thunderstorms can be expected into Tuesday. There is potential
for spotty frost in colder western Nevada valleys Wednesday
morning. Otherwise, a gradual warming trend along with dry
conditions are expected the remainder of the week into next
weekend.
&&
.SHORT TERM...
The cold front today is slowly moving south and is located around
the Highway 50 corridor as of 2 pm. Locally critical fire weather
conditions are being observed for areas south of Highway 50 due to
20 to 30 mph wind gusts and low humidity. North of the front,
humidity values have begun to increase but gusty winds are still
a concern. Winds will become light overnight, except over ridges,
where breezes will continue into Tuesday morning. Gusty winds are
also bringing choppy conditions to Lake Tahoe and a Lake Wind
Advisory remains in effect through this evening.
Light showers are being observed on radar along and just behind
the cold front through the central Nevada Basin and Range into
eastern Nevada. As the upper low begins to drop south into
northern California and Nevada this evening, a vort max rotating
around the base will help to trigger showers and thunderstorms
through the Lassen/Plumas county areas. HRRR simulations have been
consistently showing this in addition to the GFS and NAM for late
this afternoon into the evening. Wetting rains are possible, but
it will be very hit or miss. These storms also have the potential
to impact the Willard Fire with brief heavy rain, small hail, and
gusty outflow winds.
Additional showers and thunderstorms are possible under the cold
core of the low on Tuesday, but precipitation amounts will
generally be light. One exception is under a deformation axis where
0.25" is likely. Deformation band placement is notoriously hard to
pinpoint and small differences of just 50 miles will have a
significant impact on the amount of precipitation locations
receive. Most forecast simulations are showing the band extending
through central Nevada, but a few take it farther west. For now,
am leaning toward the eastern solution and have trended the
forecast in this direction. The other concern is the potential for
light snow accumulation down to about 9000 feet. Anyone with
outdoor plans in the high Sierra should plan accordingly.
Much cooler temperatures are expected on Tuesday, with highs
running 10 to 15 degrees below normal. As the system exits Tuesday
night, skies will begin to clear and patchy frost is possible
through colder valleys early Wednesday morning. A good rule of
thumb is if your forecast low temperature is 40 degrees or lower,
you may want to cover sensitive vegetation. -Dawn
.LONG TERM...Thursday through Monday...
General troughiness remains over the Southwest for the end of the
week heading into the weekend with ridging building into the
Pacific Northwest. This will bring a gradual warming trend along
with dry conditions and light winds.
There is still some uncertainty regarding the end of the weekend
into the early part of next week with the potential for a weak
trough to either brush by to the north of the region, or drop
farther south. Most guidance and ensembles are pointing toward a
northern track, which would bring some light afternoon breezes
Sunday and Monday, but not as strong as a southern track would
produce. The forecast looks to remain dry through the period.
-Dawn
&&
.AVIATION...
The cold front has already passed through all terminals north of
Highway 50 with gusty southwest to west winds up to 25 kts
continuing through this evening. The low level wind shear threat
has likely ended north of the front, but for areas south of
Highway 50 a short period of wind shear is likely along the cold
front as wind turn from the west to the north northeast.
Surface winds will become east north east north of Interstate 80
with north to northwest south of there heading into Tuesday, but
will be light. Wind aloft will generally be from the north.
Isolated showers and thunderstorms are possible this afternoon and
evening north of KSVE-KNFL line and east of Highway 95. Chances
will expand across much of the Sierra and northwest Nevada
overnight into Tuesday with a cold area of low pressure overhead.
Storms may produce brief heavy rainfall, small hail, and erratic
wind gusts in addition to obscuring terrain.
Drier conditions are expected Wednesday and through the remainder
of the week along with light winds. -Dawn
&&
.REV Watches/Warnings/Advisories...
NV...Lake Wind Advisory until 8 PM PDT this evening for Lake Tahoe in
NVZ002.
CA...Lake Wind Advisory until 8 PM PDT this evening for Lake Tahoe in
CAZ072.
&&
$$
For more information from the National Weather Service visit...
http://weather.gov/reno