Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/29/16
Area Forecast Discussion
National Weather Service Caribou ME
1013 PM EDT Wed Sep 28 2016
.SYNOPSIS...
High pressure ridge will remain across the region into Saturday.
Low pressure will gradually approach from the south on Sunday.
&&
.NEAR TERM /THROUGH THURSDAY/...
1010 pm update...
Quick update to lwr temps, mainly acrs the north by 1-2 degrees as
dwpts hv dipped into the m30s acrs the St. John Vly. With skies
beginning to clr, cannot rule out patchy frost in these areas and
hv added this into nrn Aroostook well aft midnight. Locales near
rvr vlys can expect to see patchy fog as skies clr. Updated to be
a little more optimistic with moclr skies late tonight as 00z raob
from CAR shows an extremely thin cld lyr with clrng advancing in
fm NB acrs Downeast tonight. No other chgs needed with this
update.
Prev discussion blo...
The main challenges are cloud cover and fog potential tonight.
The latest visible satellite imagery showed clouds across northern
and coastal areas while the central portion of the CWA was seeing
sunshine. Temps varied where there was cloud cover as northern and
western areas were in the low to mid 50s north of Houlton and
Millinocket as they were running near 60. Central and interior
downeast areas were in the low to mid 60s. NNE were holding at 5
to 10 mph.
The latest GFS/NAM soundings including the HRRR showed clouds
breaking up for a time this evening across the north and west but
then returning after midnight w/the llvl moisture trapped below 2k
ft. This anticipated cloudiness can be seen residing back across
northern New Brunswick. Before this takes place, temps will fall
back for a time into the upper 30s. further to the e, the clouds
will keep temps up to around 40. Across the central and downeast
areas, mid 40s look good attm. The nne wind around 5-7 mph should
allow for the blyr to mixed some especially in the open areas.
Confidence is high enough that fog will form by early Thursday
morning. Valley and low lying locations have a chance of seeing
the fog w/the llvl moisture in place. The BUFKIT soundings point
to this as well.
High pres anchoring itself in across southern Canada will allow
for some sunshine on Thursday after some clouds and valley fog
erode by mid morning. Winds are forecast to more from the ne which
will add a chill to the air. Decided to boost Thursday afternoon
temps up from previous forecast based on how warm the central and
downeast region got(mid 60s). Northern and western areas are
expected to be in the upper 50s.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
The models are in good agreement through the period. A low
pressure system over central Kentucky with an occluded front
extending east into the North Atlantic along the coast of New
Jersey where it meets the warm and cold fronts and a high pressure
ridge across Northern New England and Eastern Canada will be the
major weather features to affect the weather through the period.
The high pressure ridge will remain in place across Maine through
the period as the warm front pushes north along the coast of
Southern New England with the front progressing to the Cape Cod by
the end of the period.
Loaded a blend of the GFS/GEM/NAM/ECMWF to smooth out the minor
differences in the models. Loaded NAWAVE4 for seas in the coastal
waters. Loaded windgust by factor tool. For QPF used RFCQFP for
first 12 hrs and a GFS for the rest.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
A low over Michigan, with an occluded front extending to Cape Cod,
a warm front extended east from Cape Cod into the north Atlantic,
and a high pressure ridge will be the main weather features for
the start of the long term period. The parent low is showing signs
that it is becoming mature. The ridge of higher pressure will hold
across northern Maine as the warm front pushes into the Northern
Gulf of Maine waters and Southwest Maine. Saturday afternoon the
Occluded front moves into Southwest Maine, the warm front moves to
Mid-Coast. By Saturday evening the occluded front moves to central
Maine, the warm front affects the entire Gulf of Maine. Sunday
morning, a secondary low forms in the Gulf of Maine, the occluded
front moves to central Maine. The parent low is co-located with
the upper level low. Sunday evening Parent low begins to fill as
the new low in the Gulf of Maine, moves east to the south coast of
central Nova Scotia. Monday morning the parent low continues to
fill and drift east over Lake Erie. Maine will remain in wrap
around precipitation associated with the remnants of the occluded
low. Monday evening an upper level troph is expected to move
through absorbing the remaining energy from the filling upper
level low and moving to the Downeast coast. Early Tuesday morning
high pressure will once again ridge into the area, and will remain
through the end of the period. A deep low is forecasted to be
moving up the coast at the starting Monday evening and is
forecasted east of the coast of North Carolina by the end of the
period.
Loaded a blend to smooth out the minor differences in the models.
Loaded NAWAVE4 for seas in the coastal waters. Loaded windgust by
factor tool.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
NEAR TERM: VFR next 24 hours with the exception of IFR
restrictions between 09z-12z Thur at all terminals.
SHORT TERM: Aviation VFR conditions all sites through the period.
Early morning Fog around water bodies may lead to some vsby issues
for PQI, BGR, and BHB, conditions will improve rapidly after
sunrise.
&&
.MARINE...
NEAR TERM: SCA remains up through Thursday afternoon. Winds have
been coming up slowly, but seas are slow to come up as they are
still residing at 5 ft. Backed this up by a few hrs and show seas
building to around 6 ft in the outer zones by tonight. Winds will
increase to around 25 kts into early Thursday.
SHORT TERM: Winds and seas will be below SCA criteria through the
period. Seas around 5 ft with wind gusts to around 22 kts at the
start of the period will subside early in the period.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...Small Craft Advisory until 5 PM EDT Thursday for ANZ050-051.
&&
$$
Near Term...Farrar/Hewitt
Short Term...Norton
Long Term...Norton
Aviation...Farrar/Hewitt/Norton
Marine...Farrar/Hewitt/Norton
Area Forecast Discussion
National Weather Service Quad Cities IA IL
705 PM CDT WED SEP 28 2016
...AVIATION UPDATE...
.SYNOPSIS...
Issued at 340 PM CDT Wed Sep 28 2016
Vertically stacked upper low seen on satellite movie loops
spinning over northern Indiana was spreading stratocumulus/stratus
as far west as the Dakotas/MN border and far western IA. Under
this canopy of clouds temperatures in the dvn cwa were rather
cool, in the upper 50s to lower 60s. Scattered showers were
located in southern WI and northern IL and were moving southwest.
&&
.SHORT TERM...(This Evening through Thursday)
ISSUED AT 340 PM CDT Wed Sep 28 2016
Forecast focus on cloud trends and temperatures.
Tonight: Any scattered showers or sprinkles should end by 7 pm
according to the HRRR with much of the night dry. Satellite loops
indicated clearing taking place in eastern WI as drier air rotates
around the upper low. We will be going with the idea this clearing
trend will spread southwest into the dvn cwa overnight. Therefore,
skies should eventually become clear or partly cloudy at most
locations. The center of the low should push southward into
southern Indiana by sunrise with high pressure ridge extending
from northern MN to the TX panhandle. Minimum temperatures will
range from the mid 40s to the lower 50s.
Thursday: Models suggest the synoptic pattern to become locked in
place with the closed upper low becoming stalled in far southern
IN or western KY, with the surface ridge from MN to TX. Most of
the cwa will enjoy sunshine especially west of the MS River closer
to the ridge. However, northeast winds coming off Lake MI due to
the cyclonic circulation around the low should spread low clouds
back into our eastern cwa. There may also be a small chance of
showers or sprinkles in our far eastern counties. Temperatures
should be warmer with highs around 70 at most locations.
.LONG TERM...(Thursday Night through Wednesday)
ISSUED AT 340 PM CDT Wed Sep 28 2016
Thursday Night...Vorticity maxima begin to pinwheel around Ohio
Valley upper-low, making westward progression back into E Iowa/
NW Illinois/and NE Missouri. Sensible weather effects will be
limited. We`ll have increasing low clouds, and a slight chance for
light showers across the far east - primarily in Bureau and Putnam
Counties.
Friday and Saturday...Models have converged on low retrograding
further NW. Went cooler for max temps, below the SuperBlend, to
account for reduced solar insolation from low stratus. Mid to upper
60s are the current going forecast but further downward adjustments
remain possible. Winds are forecast to be strongest on Friday,
between 10-20 mph (isolated higher gusts) out of the NNE.
Precipitation: Isolated to scattered showers are likely at times.
The highest PoPs are over the eastern half of the CWA and peak
between 40-50% Friday afternoon through Saturday. Further west,
chances are lower and many locations may receive little to no
measurable rain.
Sunday and Monday...Model suite in reasonable agreement weakening
the upper-level low on Sunday and tracking it to the NE through
Michigan. This will be a dry stretch of weather with temps in the
70s.
Tuesday and Wednesday...Pattern transitions into a warmer, return
flow scenario. Dewpoints may rise into the 50s; however, the best
moisture advection will probably occur on Wednesday as it pools
along a cold front. May need to remove shower chances over the
west in future updates because forcing and low-level convergence
are negligible. Wednesday...showers and thunderstorms may
accompany the front but it is too early to assess the severe
potential and coverage of storms. ..Uttech..
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
ISSUED AT 702 PM CDT Wed Sep 28 2016
VFR conditions to prevail the next 24 hours. Upper low to the east
to result fair to partly cloudy skies with any bases above 3K AGL.
Winds will be northerly at 5 to 10 MPH tonight and 10 to 20 MPH on
Thursday.
&&
.HYDROLOGY...
Issued at 100 PM CDT Wed Sep 28 2016
Overview: Most significant change was at New Boston on the
Mississippi River where the crest forecast increased from moderate
to major flood stage. Otherwise, river forecasts are largely on
track. See site specific information in the following discussion and
in recent Flood Warning Statements.
Cedar River...
Vinton: Now below major flood stage.
Cedar Rapids: Forecast to fall below major flood stage Thursday
evening or night.
Conesville: Major flooding is occurring as river level rises
rapidly. Timing of crest forecast is Thursday afternoon into
Thursday night. Confidence is moderate to high on a crest a half
foot on either side of 18.30 feet.
Wapsipinicon River...
Anamosa Shaw Rd: Forecast to fall below major flood stage this
evening.
De Witt 4S: High confidence in reaching major flood stage. Thinking
current crest forecast is on the upper end of possible outcomes.
Reasonably high probability the final crest is lower. Please
monitor for updates.
Iowa River...
Excessive amounts of water continue to propagate downstream through
the Iowa and Cedar Rivers. There is high confidence on significant
flooding. Exact timing varies by site.
Moderate confidence is associated with the crest forecasts. Current
thinking is crest forecasts are toward the upper range of what is
possible; observed crests may come in lower. Please follow forecast
information closely throughout this event.
Mississippi River...
Minor to Major flooding continues to be on track. Greatest forecast
change was at New Boston with an increased crest forecast from
moderate to major. Otherwise, latest forecasts show little to no
adjustments. Majority of the crests are projected to occur over the
weekend or early next week. Uttech
&&
.DVN Watches/Warnings/Advisories...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...Haase
SHORT TERM...Haase
LONG TERM...Uttech
AVIATION...Nichols
HYDROLOGY...Uttech
Area Forecast Discussion
National Weather Service Wilmington NC
1032 PM EDT Wed Sep 28 2016
.SYNOPSIS...
A cold front approaching from the west will slow down on Friday and
linger near or along the Carolina coast through this weekend. High
pressure will build in behind the front through early next week.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
As of 1030 PM Wednesday...Forecast area remains clear of
convection this evening. However, a second round of convection is
possible as a vorticity lobe streaks up from the south, embedded
in the mean flow between the Atlantic Ridge and deep closed low to
the west. Elevated instability will remain, and forcing within
this vort will be enough to cause more showers with isolated tstms
tonight, and this may affect a larger portion of the CWA than will
be impacted through this eve. Do not expect strong or severe
overnight, but more showers will be possible and have continued
CHC Pop through the overnight. Temperatures overnight will remain
above seasonable norms, with mins dropping only to around 70.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...Synoptic pattern changes very little
through the end of the week, although sensible weather will improve
through the period. Deep upper low across the OH VLY will remain the
dominant feature as flow becomes very slow, keeping the closed low
basically stationary through the period. This will cause a cold
front to move slowly to the east, but guidance has backed off even
further on this motion, and it is now progged to not quite make it
to the coast even by Friday night. This will keep unsettled weather
with warmer temperatures across at least the eastern third of the
CWA, while locations out towards i-95 should still break into the
drier and cooler air, especially on Friday. This is noted by much
lower RH above 850mb advecting eastward in a dry slot beneath the
upper low. However, the large ridge across the Atlantic remains
strong, and forces the moist air ahead of the front and the dry slow
to remain along the coast, while the pinched flow between these
features drives vort impulses and shower chances northward into the
region. Friday will overall be a drier and slightly cooler day than
Thursday, that will be most felt well inland, while the immediate
coast may see little change with above climo temps and scattered
aftn convection.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 300 PM Tuesday...Latest model run keeps deep cutoff upper
low a bit farther west as it tracks up toward the Great Lakes over
the weekend. Therefore the sfc front and deeper moisture should remain
aligned parallel, just along the coast rather than off shore.
Plenty of dry air will wrap around the upper low into the
Carolinas aloft, but the lower dewpoint air behind the sfc
boundary may struggle to make it to the coast. Also, the sfc
boundary will remain a focal point for convective development and
although the air aloft will be drier, there should still be
shallow convection possible along and east of the boundary. There
will be a sharp gradient between the drier air to the west and
moister air to the east, but exactly where that will lie is tough
to say. The models are trending on keeping the boundary farther
west, along the coast, rather than off shore. This will mean more
clouds, showers and more humid air in place over the eastern half
or third of our area, but as you move inland there will be greater
amounts of sunshine and drier air. The latest pcp water shows
values up close to 2 inches from the tip of Cape Fear up to
Hatteras while west of I-95 will have PWATS less than an inch with
even lower amounts as you head W-SW. Essentially, the drier air
will wrap around from the SW aloft and N-NW at the sfc and it will
be more of a dewpoint gradient rather than temps. Daytime highs
will remain in the 80s most places. The guidance has backed off on
the cooler overnight lows due to the lack of lower dewpoint air
moving in, but I still think many places inland will get down
toward 60 early Sat.
As the the mid to upper low lifts north Sunday through early next
week, the lingering boundary will be pulled farther back on shore
as it dissipates through Monday. The winds should shift around to
the NE to E bringing some moister air back inland. Overall, places
inland and west of surface boundary will see a greater amount of
sunshine while places east of boundary will see a greater amount
of clouds and chc of pcp.
Heading into the middle of next week, the forecast become further
complicated by the differences in the models as to the track and
timing of Tropical Cyclone Mathew. For now, this system looks like
it will track westward and eventually turn up around the Atlantic
Ridge. The GFS is much faster with this system and we will have to
see how this evolves to determine how or if this affects the
southeast coast. For now, the greatest effects may be over the
coastal waters in pulses of swells and increasing gradient winds
eventually drive up the seas.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
As of 00Z...A frontal boundary will continue remain nearly
stationary over the western portion of the region. Much of the
convection will start to wind down, however the HRRR model has been
fairly consistent with overnight convection nearly in the same place
as the convection currently ongoing. It may be a reflection of what
is leftover from the sea breeze boundary. Some of this convection
will try to make it to the coast, but will weaken as it does so.
Thursday, some scattered convection possible by mid to late
afternoon, still associated with a weak frontal boundary and an
upper low well west of the region.
EXTENDED OUTLOOK...Primarily VFR. Isolated to scattered afternoon
showers through much the period, although limited in strength and
coverage due to dry air aloft.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 1030 PM Wednesday...Latest obs continue to show SE winds of
around 10 kts with 3 ft seas. Forecast in good shape with no
changes needed. Previous discussion follows:
Stalled front continues to sit NW of the waters, with a weak
pressure gradient remaining in place. Winds will slowly veer from
present S/SE to SW overnight, along with a slight increase in
speed from 5-10 kts to a more uniform 10 kts. This will create
seas of 2-3 ft, with a southerly wind wave and low amplitude SE
swell comprising the spectrum. Showers with isolated tstms will be
possible across the waters late tonight as well.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
As of 300 PM Wednesday...Slow moving cold front will drag west to
east through the short term, finally approaching or stalling across
the waters Friday night. This will keep the waters in the warm
sector with S/SW winds of 10-15 kts expected through most of the
period, possibly shifting to the W/NW Friday night. These persistent
winds combined with the offshore high pressure will keep a 5-6 sec
southerly wind wave and 9-10 sec SE swell in the spectrum, creating
2-3 ft seas.
LONG TERM/SATURDAY THROUGH MONDAY/...
As of 300 PM Tuesday...A cold front will run parallel along or
near the Carolina coast...weakening through early next week.
Overall expect more northerly winds on west side of front to come
around to the NE to E as weakening boundary gets drawn back westward
as upper low lifts off to the north through the period, but great
variability is possible. Southerly winds should continue to the east
of the boundary. Seas will generally remain 2 to 3 ft over most
waters but a slight rise will be seen due to some longer period SE
swells mixing in through the weekend into early next week.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...RGZ
NEAR TERM...REK/JDW
SHORT TERM...JDW
LONG TERM...RGZ
AVIATION...DL
MARINE...REK/JDW/RGZ
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
826 PM CDT Wed Sep 28 2016
.UPDATE...
826 PM CDT
For evening update...
Clusters of showers and isolated thunderstorms continue to wrap
cyclonically west-southwest across southern Lake Michigan and
parts of northeast IL and northwest IN this evening, in association
with smaller scale vort lobes rotating about upper low centered
over Indiana. Cool air aloft associated with the upper low and
warm early autumn Lake Michigan waters were combining to yield
some impressive lake-enhanced instability (800 J/kg per RAP) and
a few stronger cells moving into the Chicago area earlier this
evening, along with a few waterspouts. These same RAP soundings
suggest instability will weaken somewhat and become more shallow
late this evening/overnight, which should allow thunder and spout
potential to diminish as well. Overall, going forecast generally
in good shape, though did expand higher pop coverage a little
farther north/west across most of metro area to match radar
trends. Focus for additional scattered showers overnight should
shift gradually south as the center of the upper low also drifts
slowly south tonight.
Temperatures are not expected to vary too much from current
readings in the 50s overnight, especially closer to Lake Michigan
where blustery north-northeast winds will help prevent much
radiational cooling. Mins are expected to range from the lower 50s
across north central IL, to the mid-upper 50s across the City.
Updated grids/zfp/etc available.
Ratzer
&&
.SHORT TERM...
309 PM CDT
Through Thursday...
The main forecast concern continues to be with shower activity
driven by the well defined upper level low pressure pivoting
southward across the region. The current showers well inland are
likely diurnally driven, with dissipation expected by dark skies
clearing to at least partly cloudy across north central Illinois.
Closer to the lake, showers have been driven and aided by
impressive lake effect setup over the lake. After the showers over
northeast IL and far NW IN as of mid afternoon pivot further
inland and dissipate, some isolated or scattered development may
occur. Thereafter, high resolution guidance is consistent on an
organized area of showers pivoting westward across the lake and
affecting portions of NE IL and NW IN through early to mid
evening. There should then be a lull followed by more at least
scattered showers associated with upper low with some lake
enhancement possible overnight into early Thursday. This would be
most likely to occur mainly east/southeast of I-55.
More of the same can be expected on Thursday, with respect to
occasional showers and a good bet at lake effect/lake enhancement.
However with the upper low farther south, far north and northwest
parts of the area, including Rockford and vicinity, could stay
completely dry. Cannot rule out an isolated rumble of thunder
east/southeast of I-55. Warming aloft should enable warmer
temperatures in the 60s to around 70, though am concerned with
persistent clouds and strong onshore flow, the lakeshore could be
kept cooler than in current forecast. It will be a breezy day with
northeast winds gusting to 25-30 mph, and up to 35 mph near the
lake.
RC
&&
.LONG TERM...
316 PM CDT
Thursday night through Wednesday...
The upper level low that brought fall conditions to the region today
will impact the region through most of the weekend. The low
retrogrades north Friday afternoon through Saturday, but guidance
differs on how far west the low will be when it pushes north. There
is a chance that the low may push right back over the region which
could lead to another round of cooler than normal temps late this
week. Have much more confidence in scattered showers and gloomy
conditions through the end of the week due to the low. Bands of
vorticity will produce showers through the weekend. Friday in
particular may be blustery with wind gusts up to 25 mph and
occasional showers. Guidance features some CAPE so kept a chance of
thunderstorms in the afternoon south of I-88. High temps look to be
in the mid 60s.
The low finally shifts east early next week and an upper level ridge
builds overhead. Temperatures become more seasonal in the low to
mid 70s and then increase to above average with mid to upper 80s
possible mid next week. The next chance of widespread rain arrives
mid week as well along the next low`s cold front.
JEE
&&
.AVIATION...
For the 00Z TAFs...
Gusty northeast winds and a few occasional waves of SHRA and
possibly a TSRA will continue through the next 24 hours. Winds
will likely be strongest late tonight through Thursday when
occasional gusts to around 30kt are likely. CIGS will likely vary
between VFR and upper end MVFR through the period.
Izzi
&&
.MARINE...
332 PM CDT
Strong north-northeast winds and high waves will be the story
through Friday evening. A period of gale force winds/gusts still
appears probable tonight on the south half of the lake and near
shore waters. Latest guidance suggests that after a brief lull to
start Thursday, there could be a brief period where winds increase
back to gale force during the day on Thursday. If confidence
increases in this scenario, the Gale Warning may need to be
extended into Thursday afternoon. This may be followed by yet
another brief period of gales or occasional gales Thursday night,
followed by solid 30 kt east-northeast winds on Friday. Winds will
diminish Friday night into Saturday, with peak speeds around 20 kt
on Saturday and then light northerly and northeast winds of 15 kt
or less Sunday and Monday.
Cold air aloft over the lake will continue to provide a favorable
setup for at least some potential for isolated waterspouts tonight
through Friday. Mariners are advised to stay alert for the
issuance of any statements or warnings pertaining to waterspout
development.
RC
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
IN...NONE.
LM...Gale Warning...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745-LMZ777-
LMZ779 UNTIL 3 AM Thursday.
&&
$$
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Area Forecast Discussion
National Weather Service Marquette MI
755 PM EDT Wed Sep 28 2016
.SHORT TERM...(This evening through Thursday)
Issued at 415 PM EDT WED SEP 28 2016
WV imagery and RAP analysis indicated a mid/upper level low over nrn
Indiana and a ridge from the wrn plains into nrn Ontario. At the
surface ne winds prevailed between a ridge into nw Ontario and the
low over IN. Although the deeper moisture had departed, radar showed
isold/sct -shra over the n and w portions of the cwa as 850 mb temps
around 5C,,daytime heating, and cyclonic flow with low level
moisture supported the light pcpn.
Tonight, expect that abundant moisture below 850 mb, and 850 mb
temps remaining around 5C (water temps from 11C-15C) will be enough
to sustain some isold -shra into the north and west, downwind from
ene to ne flow off the lake, mainly over the Huron Mountains and
from IWD to Ontonagon. Otherwise, temps will drop into the mid and
upper 40s inland and around low to mid 50s near the Great Lakes.
Thursday, mostly sunny skies over the east half and decreasing
clouds over the west as the sfc ridge builds into the area will
allow temps to climb into the mid 60s west and to near 70 south and
east.
.LONG TERM...(Thursday night through Wednesday)
Issued at 325 PM EDT WED SEP 28 2016
Dry wx accompanying sfc hi pres wl dominate the the beginning of the
medium range period. But as the closed lo pres responsible for the
recent pcpn lifts fm the OH River Valley back over Lower MI btwn a
deepening wrn trof and a bldg rdg off the e coast, some showers may
return as early as Sat and linger thru the weekend, especially over
se Upr MI. Any weekend showers wl give way to dry wx early next week
as another hi pres rdg dominates under a bldg upr rdg to the e of
the slow moving wrn trof. Although Thu ngt could be chilly
especially over the interior w under the initial hi pres rdg, above
normal temps should dominate the medium/extended range period.
Thu ngt...Sfc hi pres rdg axis stretching fm near James Bay into the
Upr Lks and area of mid lvl dry air to the n of nearly stnry closed
lo in the OH River Valley wl bring tranquil wx to Upr MI. Expect the
lowest min temps that may dip into the 30s at the interior cold
spots over the w under axis of lowest pwat arnd 0.5 inch/light
winds. Tended aob the lo end of guidance in this area for the lo
temps. A steadier e wind under the tighter pres gradient btwn the hi
pres rdg and the lo pres to the s as well as perhaps some hi clds
closer to the closed lo wl limit the diurnal temp fall over the se,
especially near the warming influence of Lk MI.
Fri...The closed lo to the sse is progged to move slowly to the n.
Although the deep lyr forcing associated with this disturbance wl
remain to the se, expect some incrsg hi clds as h5 hgts fall slowly.
The area from Ironwood to the Keweenaw wl see the most unfiltered
sunshine. h85 temps fcst arnd 10C wl support max temps climbing at
least near 70 away fm the moderating influence of the lks in a slowly
incrsg ene wind.
Fri ngt into Sun...As an upr trof deepens over the w and an upr rdg
blds in the wrn Atlantic Ocean, the sly wind component btwn these
larger scale features is progged to lift the closed lo back nwd and
over Lower MI. The medium range guidance is in good agreement
showing incrsg mid lvl rh but hints the most sgnft deep lyr forcing
wl tend to remain to the ese of the cwa. Since the initially dry
llvls associated with the slowly retreating sfc hi pres rdg wl have
to be overcome, suspect pcpn wl have a hard time overspreading the
area, especially the nw. Plan to go with no more than chc pops, hiest
over the se cwa closer to the closed lo center. Although the clds wl
tend to hold max temps not too far fm normal, min temps on Fri ngt
and Sat ngt should run well above avg.
Sun ngt thru Wed...The closed lo is progged to exit to the e on Sun
ngt/Mon as an upr rdg blds over the Great Lks to the e of the
deepening Rockies trof. Any lingering pcpn should diminish late on
Sun as the closed lo/mid lvl mstr exit to the e and a sfc hi pres
rdg axis to the se of Hudson Bay hi pres blds over the wrn Great
Lks. Then expect dry wx on Mon into at least Wed as the sprawling
sfc hi center blds toward New England/the Cndn Maritimes. The incrsg
sly flow btwn this hi and falling mslp in the Plains ahead of the
deep wrn trof wl advect unseasonably warm air into the Upr Lks. h85
temps are progged to reach as hi as 10-12C by Tue. Showers ahead of
the sfc lo pres/cold fnt ahead of the slow moving wrn trof may
arrive by Wed.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 741 PM EDT WED SEP 28 2016
Northeast winds north of departing low pressure system will keep
some lower cigs across the area tonight. Expect the more persistent
MVFR cigs to be at SAW where cigs may dip to IFR. Expect MVFR cigs
to scour out at CMX and SAW by late evening. Conditions should
improve to VFR at IWD by late Thursday morning.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 415 PM EDT WED SEP 28 2016
Weakening low pressure will result in 15-25 kt winds late this
afternoon diminishing to less than 20 kts tonight. A general weak
pressure gradient lingering into the weekend should keep east to
northeast winds at 20 kts or less.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Beach Hazards Statement until 8 PM EDT this evening for MIZ005-
006.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...JLB
LONG TERM...KC
AVIATION...Voss
MARINE...JLB
Area Forecast Discussion
National Weather Service Omaha/Valley NE
659 PM CDT WED SEP 28 2016
.SHORT TERM...(tonight through Saturday)
Issued at 243 PM CDT WED SEP 28 2016
Quiet weather continues in the short term with the upper low to
our east continuing to spin across the Ohio Valley. The western
edge of the clouds have affected western Iowa today, The big
question is how far west the moisture associated with the clouds
can move west overnight, and whether any clouds would develop from
that. Will mainly have clouds impacting western Iowa, with not
much development across eastern NE.
Another cool night tonight in the 40s and again Thursday night. Highs
Thursday again in the upper 60s, but then lower 70s for Friday and
Saturday. Could see a few more mid/high clouds Saturday, but dry
weather continues with light winds through the period.
.LONG TERM...(Saturday night through Wednesday)
Issued at 243 PM CDT WED SEP 28 2016
Weak ridging across the Plains early in the period. ECMWF still
hints at a weak disturbance possible underneath the ridge Sunday
into Sunday night, but the GFS has backed off off on any precip.
Will maintain slight chance pops that were already in the forecast
but confidence is low. Then southwesterly flow develops aloft,
with breezy southerly surface flow. This should help boost temps
back into the 75-80 range Monday into Tuesday. Rain chances back
into the forecast Monday night into Tuesday, then Tuesday night
into Wednesday as a cold front moves into the area. Cooler
Wednesday behind the front with temps back to normal in the lower
70s.
&&
.AVIATION...(00Z TAFS for KOFK...KLNK and KOMA.)
Issued at 647 PM CDT WED SEP 28 2016
Satellite imagery and obs show moisture around fl040-050 over Iowa
with variable sct-ovc conditions. Low level flow from the
northeast should continue to advect this moisture westward into
eastern Nebraska. For now will mention scattered deck due to the
patchy nature of the clouds forecast by the rap and see how much
the clouds break up after sunset. Some patchy fog possible
Thursday am for an hour or so and included a mention at koma around
12z with light and variable winds.
&&
.OAX Watches/Warnings/Advisories...
NE...None.
IA...None.
&&
$$
SHORT TERM...DeWald
LONG TERM...DeWald
AVIATION...Zapotocny
Area Forecast Discussion
National Weather Service Nashville TN
704 PM CDT WED SEP 28 2016
.UPDATE...
FOR 00Z AVIATION DISCUSSION.
&&
.DISCUSSION...
Cold front is clearly depicted on the latest sfc analysis. The
boundary stretches from just east of ckv southwest through the
waverly area. Scattered light shower activity is oriented along and
just behind the boundary. The upper trough axis is providing the
post frontal lift with some pva moving through the area. The
westward extent of the moisture does cut off just north of ckv.
Thus, will continue with the higher pops east theme for the fcst.
Latest HRRR in line with the southward moving band of showers. By
06z the activity will push east of the area. Will only include a
slight chance of showers aft midnight, some 30 pop prior.
Moving forward, the upper low will move very slowly southward
through tomorrow afternoon. On Friday it will start to lift slowly
northward. So, given the close proximity of the upper low and a
continuation of weak impulses on the back side, low shower chances
will persist for a good chunk of our area through Friday.
Examining the 850 mb moisture levels and the higher convective
daytime lapse rates, pops will be into the chance category across
the north and east for both Thursday and Friday afternoons. Still
looking at some isol t on Thursday afternoon as the closer proximity
of the upper low exists and showalter values drop.
For the near term temps, a cool period is in store. The clouds and
light shower activity will keep highs mostly in the 65 to 70 degree
range, and lows in the 50s. I am thinking about undercutting
guidance by several degrees tomorrow, particularly across
northern areas. The close proximity of the upper low may keep us
cooler.
In the ext fcst, upper low will lift out on Saturday and will be
replaced by upper ridging for Tues and Wed. This will equate to a
dry period with a warming trend. High temps will start out in the
low to mid 70s on Saturday, but will reach the mid 80s by Wednesday.
Lows in the 50s will warm into the lower 60s by Wednesday.
&&
.AVIATION...
00Z TAF DISCUSSION.
Expect a cold front to pass the CSV area in the next couple of
hours, switching winds to the north, as has already occurred at
BNA and CKV. Band of Mid Clouds should continue to sweep eastward
with the front, allowing for some clearing or at least partial
clearing at BNA and CKV later this evening. However, low clouds
are forecast to develop later tonight and hang around on Thursday,
along with a chance for showers as a closed upper low drops
southward across Kentucky.
If an overnight shower passes directly over BNA or CSV, vsbys
could briefly drop to MVFR. However, since confidence in MVFR is
so low for the first part of the night, have kept prevailing
conditions as VFR through 08z. However, expect MVFR ceilings to
develop between 08z and 11z, with a possibility for periods of IFR
as well through at least 15z. As upper low remains in our neck of
the woods throughout the day on Thursday, will keep ceilings MVFR
lingering throughout the afternoon.
&&
.OHX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
DISCUSSION......13
AVIATION........19
Area Forecast Discussion
National Weather Service Blacksburg VA
938 PM EDT Wed Sep 28 2016
.SYNOPSIS...
A strong upper level area of low pressure will moving from the
Great Lakes to the Tennessee Valley tonight and Friday. This
system will combine with a low pressure system over the Mid
Atlantic region to produce several periods of showers and
thunderstorms tonight through Friday night. The low will move
northeast, away from the region, resulting in drier weather
this weekend.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 935 PM EDT Wednesday...
Severe Thunderstorm Watch 488 will be allowed to expire at 10pm.
Still with high shear environment and upper level support isolated
large hail will be a threat along/east of the Blue Ridge for a few
more hours. Starting to watch for hydro concerns, and current
flash flood watch covers the area we are most concerned about
overnight into Thursday. Could possibly see it being extended
west toward Roanoke, but will wait and see how the heavier rains
set up over the next several hours.
Previous evening discussion...
Cleared portions of Severe Thunderstorm Watch 488 roughly west of
a line from Lynchburg to Martinsville to Yadkinville.
Best instability resides east of this line, but especially over
central NC. Still seeing good shear values along and east of the
Blue Ridge. HRRR shows redevelopment this evening over the
foothills of NC north into the New River and Roanoke Valleys. Will
have to watch for isolated wind issues, but given loss of heating
threat should stay isolated.
Previous discussion from mid afternoon...
Closed upper low over Michigan will fill slightly and move south into
southern Indiana by Thursday morning. Strongest vorticity
advection reaches the central Appalachians late tonight. Cold pool
aloft also moves over the mountains late tonight and Thursday with
500 mb temperatures down to -20 in far southwest Virginia.
Diffluence aloft will also produce some lift with the central and
eastern Virginia within the right rear quadrant of the upper jet
overnight. With the abundant lift and moisture east of the Blue
Ridge, will be increasing probability of precipitation on Thursday.
A surface cold front with associated with the upper low will approach
the Appalachians Thursday morning. Models bring a chance of showers
into southwest Virginia with this feature by Thursday afternoon. By
late Thursday this front will merge with the main surface low over
Virginia.
Best instability and most favorable shear profiles are in the
piedmont this afternoon and tonight. In locations with heating the
convective available potential energy may reach 2500 J/KG this
afternoon. The enhanced low level winds will be along the
boundary north of a HSP to FVX line.
Have kept maximum temperatures below guidance on Thursday based on
the amount of rain and cloud cover expected.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/...
As of 320 PM EDT Wednesday...
A closed upper low centered near SDF Thursday evening will stall
across the Ohio River Basin through Friday night. At the same time,
a series of disturbances, including complex frontal system will
interact with the deep atlantic moisture and pulse along the mid
Atlantic Seaboard.
As a result, scattered to numerous showers and thunderstorms will
continue around the low and along the boundary. Some of the
thunderstorms could be strong with gusty winds,hail and heavy
downpours Thursday evening into Thursday night. The swody2 has
placed much of the CWA in Marginal risk of severe with main threat
being hail and gusty wind. Convection is expected to diminish with
the loss of daytime heating and the subsequent instability axis
overnight Thursday into Friday morning. Low temperatures Thursday
night will range from the upper 40s in the mountains to the lower
60s in the Piedmont.
Considerable clouds with scattered showers and a few thunderstorms
will continue Friday. High temperatures Friday will remain
relatively cool with readings from the mid 60s in the Mountain to
the mid 70s in the Piedmont. Isolated to scattered showers will
continue Friday night. The Best chances for rain will occur across
the North. Low temperatures friday night will vary from the mid 40s
in the western Mountains to the upper 50s in the Piedmont.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 320 PM EDT Wednesday...
Closed upper low centered near Saturday morning will lift
northeast and reach the St. Lawrence river valley by Sunday night.
Then, the low center will open up and weaken as it moves across
New England Monday and moves into the Atlantic ocean on Tuesday.
The exact evolution of the large scale patterns will affect the
eventual track of what is forecasted by NHC to be Hurricane Matthew.
The storm may threaten the southeast coast next week. This is being
monitored by the NHC and WPC.
For much of the extended ISC grids leaned towards WPC which was a
blend of the 00Z GFS/GEFS MEAN/ECMWF ENS MEAN. Temperatures will
start cooler for Saturday with continued improvement as
precip/cloudcover comes to an end, then temperatures begin to
moderate Sunday into Wednesday.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
As of 725 PM EDT Wednesday...
Main threat of tsra will be close to Danville this evening with
VCSH across LYH/ROA/BCB. High-res models favor more shower
coverage as far west as BCB, but for now will keep it VCSH.
As an upper low moves south of the Great Lakes tonight and
Thursday...a cold front will approach the Appalachians from the
west. This front will merge with a stationary low pressure system
over Virginia on Thursday.
Ceilings and vsbys will at times drop to IFR but most will be MVFR
to VFR overnight, with best chance of VFR this evening in BLF/LWB.
Question is how much fog forms with rain earlier today and any
clearing potentially leading for IFR or lower conditions.
Confidence at this time is high enough of IFR fog, otherwise MVFR
or higher.
Thursday will be a day of scattered to numerous coverage of shower
and storms, so expect any lower cigs to rise to MVFR to VFR by
midday.
Extended aviation discussion...
A deep upper low will remain over the Ohio and Tennessee Valleys
through Friday night. This will keep variable clouds, MVFR cigs,
and periods of -SHRA across the region through much of the period.
Should finally see VFR return during Saturday and continue Monday
as the upper low lifts north and weak high pressure builds in.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Flash Flood Watch through Thursday afternoon for VAZ035-
044>047-058-059.
NC...None.
WV...None.
&&
$$
SYNOPSIS...AMS
NEAR TERM...AMS/WP
SHORT TERM...KK
LONG TERM...KK
AVIATION...AMS/JH/WP
Area Forecast Discussion
National Weather Service Albany NY
419 AM EDT THU SEP 29 2016
.SYNOPSIS...
Despite some clouds, mainly dry weather is expected through the
day today with seasonable temperatures. A slow moving low pressure
system near the Ohio Valley will gradually move towards New York
and New England for Friday into the weekend, allowing for an increased
threat for rain showers with cooler temperatures. The storm system
may linger into early next week with a continued chance for rain
showers.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
As of 419 AM EDT...A large and closed off upper level low is
situated over the Midwest and Ohio Valley. At the same time, upper
level ridging is in place off the eastern seaboard across the
western Atlantic Ocean, while a strong area of surface high
pressure is located over Quebec. The combination of these features
is allowing for plenty of mid and high level moisture to move up
the eastern seaboard, while the low-level flow is out of the east
to northeast.
IR satellite imagery shows plenty of mid/high level clouds are in
place over the area. Showers have been ongoing south and west of
the region over Pennsylvania and western New York, but the flow
around the upper level low is keeping these showers generally
away from the area. The upper level low is expected to sit and
spin over the central Ohio River Valley today, so the bulk of
these showers probably won`t be able to make much more northeast
progress towards our area. Still, will allow for slight chance to
chance pops over our southern and western areas in case some
showers are able to sneak into these areas. The latest 3km HRRR
does show a few rain showers making it into the eastern Catskills
briefly this morning, so some raindrops are certainly possible
there today.
Otherwise, it looks to stay fairly dry today, but clouds look to
remain in place based on what`s upstream in the satellite imagery.
Some breaks are possible for northern areas, thanks to some
subsidence from the nearby high pressure northeast of the area and
drier air moving in with the low-level northeast flow. As a
result, temps today look warmest across northern areas with upper
60s in those areas. Meanwhile, southern areas look to stay the
coolest thanks to the more clouds/possible precip, with upper 50s
to mid 60s further south and west.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/...
There will be an increased threat for rain showers through the
short-term period, as the upper level low slowly starts to make
some eastern progress.
Most of tonight will continue to be dry, as the upper level low
continues to spin over the Ohio Valley. However, it should
continue to be fairly cloudy with lows in the 40s to low 50s.
Some far northern areas may drop into the upper 30s if a few
breaks in the cloud cover can occur.
Although the main upper level dynamics continues to be situated
well west of the area on Friday, the mid-level flow starts to
switch to the S-SE, which should continue to advect more moisture
into the area off the western Atlantic. Some showers are possible
as early as Friday afternoon, mainly for far southern areas. Temps
on Friday will range from the upper 50s to upper 60s, with the
warmest temps across northern areas.
The best chance for showers looks to be Friday night into
Saturday/Sat Night, as the upper level low starts to shift
towards the eastern Ohio Valley and weak impulses rotating around
it help promote the formation of showers. PWAT values look to rise
to around 1.50" for southern areas on Saturday, so there could be
some locally heavier burst of rain at times. The exact timing and
amounts of rainfall is tricky as this time due to uncertainty
regarding the track/timing of the upper level low, but best chance
for showers looks to be across southern areas. Min temps will
generally be in the mid 40s to mid 50s and highs will be in mid
50s to low 60s.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The extended forecast begins unsettled with the pesky cutoff low
still impacting the forecast area into early next week.
However...high pressure will build in Tuesday into the mid-week with
fair and dry weather returning.
Sunday to Monday...Good agreement with the medium range guidance
that the cutoff low lifts back north to northeast into the Great
Lakes Region by the 2nd half of the weekend. An occluded front will
extend south to southeast of the sfc reflection of the cutoff over
portions of PA and NY. A short-wave rotating around the cutoff
will focus some scattered showers with a decent fetch of moisture.
PWATS will be 1 to 2 standard deviations above normal according to
the latest GEFS. Pops were kept in the high chance category. Highs
on Sunday will be near early OCT normals with mid to upper 60s
across most of the fcst area with some upper 50s to lower 60s over
the higher terrain. Lows Sunday night will generally be in the
upper 40s to mid 50s. The upper low opens up and the cold pool
drifts over NY and New England. Diurnally-timed scattered showers
will be possible again. Temps will be similar to Sunday.
Monday night into Tuesday...The showers should diminish early in the
evening with the loss of the diurnal heating. The upper trough axis
finally moves downstream with some ridging building in from the
Great Lakes Region...and the MS River Valley. A weak short-wave in
the north to northwest flow aloft may trigger isolated showers on
Tuesday, but it should be mainly dry with the ridge building in.
Lows Monday night will continue to be in the mid 40s to mid
50s...and highs will be similar to the previous days with mid to
upper 60s in the valley areas...and upper 50s to lower 60s over the
mountains.
Tuesday night into Wednesday...Fair and dry early Autumn weather
continues with the sfc anticyclone building in over NY and New
England from southeast Quebec. Good radiational cooling conditions
will allow for lows in the 40s. Highs will continue to be near
normal for the first week of OCT.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
High pressure continues to be situated near eastern Quebec with low
pressure near the OH Valley. An east to northeast onshore flow will
continue the next 24 hours ending 06Z/FRI.
MVFR cigs will continue at KPSF/KPOU with a small chance of a shower
closer to KPOU. A VCSH group was used there. CIGS will be in the 1.5-
2.5 kft AGL. Further north towards KALB/KGFL mid and high clouds
will persist this morning. The ridge will continue to build in late
this morning into the afternoon and expect a return to VFR
conditions at all the sites. Lingering mid and high clouds will
persist into the early evening.
The winds will be light to calm at KALB/KGFL this morning. North
to northeast winds of 5-10 kts will continue at KPOU/KPSF with
some gusts close to 20 kts at KPSF. The winds will increase from
the east to northeast at 8-12 kts late this morning into the
afternoon with gusts close to 20-25 kts at KPSF. The winds will
slacken a bit after 00Z/FRI.
Outlook...
Thursday through Monday: Moderate Operational Impact. Chance of
SHRA.
&&
.FIRE WEATHER...
Plenty of clouds will be in place over the next few days as a slow
moving storm system impacts the region. Some showers will be
possible as well, mainly for tomorrow into the weekend. A wetting
rainfall will likely occur between Friday and Saturday across much
of the area.
RH values will only fall to 55 to 65 percent this afternoon. RH
values for Friday into the weekend will generally be above 60
percent.
East to northeast winds will be 10 to 15 mph today. Winds at
similar direction and speed are expected to continue tomorrow into
Saturday as well.
&&
.HYDROLOGY...
No flooding is expected over the next five days.
Dry weather has continued so far this month, but some needed
rainfall is finally in the forecast. A slow moving area of low
pressure will bring some rain showers to the region over the next
few days, with the bulk of the showers occurring between Friday
and Sunday. Amounts will vary from north to south and are still
rather uncertain due to the storm track, but total amounts look
to be at least a half inch. Southern parts of the region may see
over an inch of this much needed rainfall by early next week.
While it won`t end the drought conditions in place, it will
certainly help.
For details on specific area rivers and lakes, including observed
and forecast river stages and lake elevations, please visit the
Advanced Hydrologic Prediction Service /AHPS/ graphs on our
website.
&&
.ALY WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
MA...None.
VT...None.
&&
$$
SYNOPSIS...Frugis
NEAR TERM...Frugis
SHORT TERM...Frugis
LONG TERM...Wasula
AVIATION...Wasula
FIRE WEATHER...Frugis
HYDROLOGY...Frugis
Area Forecast Discussion
National Weather Service Cleveland OH
308 AM EDT THU SEP 29 2016
.SYNOPSIS...
Low pressure will tend to remain near ohio through Sunday then
weaken and move off to the northeast Monday. High pressure shifts
east across the area Monday night and Tuesday then into the
northeast Wednesday.
&&
.NEAR TERM /UNTIL 6 PM THURSDAY EVENING/...
The upper low that will affect the area thru the weekend digs into
its southernmost position in KY today. Bands of shra and some tsra
will continue to rotate around the low. From now thru noon...the
models generally indicate the main band of rain rotates to the ne to
mainly be affecting the ne half of the cwa for the afternoon.
However...differences in the models don`t make this a sure bet so
will keep the pops fairly broadbrushed versus just loading the hrrr
or rap progs. With convection somewhat limited...rainfall rates
should be kept in check so not expecting any flooding today.
High temps tricky due to questions of where midday rain will be most
likely occurring. Warmest airmass temps generally over the east but
this appears to be favored location for midday rain which would hold
down the temps. Widespread cloud cover will limit temp rise
everywhere with highs mostly ending up in a 64 to 69 degree range.
&&
.SHORT TERM /6 PM THURSDAY EVENING THROUGH SUNDAY NIGHT/...
Little will change thru Sat as the upper and surface low stays in
the area then on Sun the lows will start to lift NNE to allow for
drier air to begin to spread into the area from the west later Sun
into Sun night. Won`t change the forecast a lot other than to
increase the pops and cloud cover some more.
The cumulative nature of the rainfall could begin to lead to some
flooding issues but not certain since heavier convection will be
limited. At some point...a flood watch could become necessary if a
band of moderate rain is shown to stay over the same area for a long
enough period of time. In general...tonight thru Sunday...expect to
see total rainfall range from a half an inch to maybe 2 inches with
the heavier amounts generally favored for the ne half of the cwa.
Temps should show little day to day change due to the homogeneous
nature of the airmass. Sunday will be the toughest day as cooler air
is shown to be wrapping in from the west but there may be more
sunshine to offset this difference.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
The upper level low will attempt to pull away from the area on
Monday but there a trough will still be clipping the area. The warm
lake combined with the upper level troughing will be enough to keep
some low chance POP`s in the forecast across NW PA. By Monday night
high pressure will be ridging into the area which should be enough
to end any of the remaining showers. Dry conditions are then
expected Tuesday into Wednesday with warming temperatures. Highs by
Wednesday are expected to return to the middle lower to middle 70s.
&&
.AVIATION /06Z Thursday THROUGH Monday/...
Upper level low will continue to plague the area with periods of
rain and mvfr or lower ceilings. The only exception may be in the
vicinity of KERI where the downslope flow will be able to delay
the arrival of the MVFR ceilings. There have been a few breaks in
the cloud cover near KFDY with some fog developing. Will need to
monitor this area for the potential of brief dense fog.
Otherwise expect to see MVFR/IFR conditions for most locations
beyond mid morning as the next round of showers develops and
pivots across Northern OH and NW PA. Some of the rainfall will be
moderate to heavy at times, especially in a swath from near KCAK
to KCLE to KTOL. Winds will also be on the increase today.
Easterly winds will become gusty this afternoon with gusts 25 to
35 knots possible. The strongest of these gusts will be closer to
the lakeshore.
OUTLOOK...Periods of non-VFR through Sunday.
&&
.MARINE...
East to northeast winds will be on the increase today. The longer
fetch into the Islands and Western Basin will see the largest waves.
Even the lakeshore near Erie will see winds strong enough to reach
small craft criteria. So with that said we will hoist a Small Craft
Advisory (SCA) at 14z. Winds begin to decrease on Friday for the
east half of the lake so will allow the SCA to end at 14z. The
western half of the lake will take some time to settle down so will
keep the SCA into Friday evening.
Winds will be weaker over the weekend as the upper level low begins
to fill. Southeast to south winds are expected to return at some
point Saturday and then continue into early Sunday. However by
Sunday afternoon southwesterly winds should develop.
Waterspouts remain a slim possibility across the western basin today
but confidence is too low to mention at this point in time.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Small Craft Advisory from 10 AM this morning to 10 AM EDT
Friday for LEZ147>149.
Small Craft Advisory from 10 AM this morning to 10 PM EDT
Friday for LEZ142>146.
&&
$$
SYNOPSIS...Adams
NEAR TERM...Adams
SHORT TERM...Adams
LONG TERM...Mullen
AVIATION...Mullen
MARINE...Mullen
Area Forecast Discussion
National Weather Service State College PA
510 AM EDT Thu Sep 29 2016
.SYNOPSIS...
A widespread moderate to locally heavy rain event will continue
through tonight. Minor flooding impacts are likely across the
southern half of central PA. Unsettled weather with occasional
lighter rain showers will persist into the weekend with a gradual
drying trend by early next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
The 29/00z guidance remained in good agreement with the deep upper
low that is forecast to settle further south from southern IN into
central KY today before lifting gradually back to the north after
00-06z Friday. The ongoing rain shield is being handled pretty well
by the HI-RES guidance. The highest rain amounts in the last ~6
hours generally range from 0.75 to 1.5 inches across Bedford to
Adams County.
Radar trends and latest HRRR suggest the north-south heavy rain
band developing near the I-95 corridor from DCA to near RIC may
focus into the Lower Susquehanna Valley through mid morning, as
deep moisture from the Atlantic is driven inland by anomalous ESE
LLJ and intersects a frontal boundary/convergence axis. This
scenario is also hinted at by the HIRES NCAR ensemble mean QPF
which shows a stripe of 2+ inch amounts.
The strength of the upslope flow and high PW transport along with
some elevated instability will maintain a favorable environment
for heavy rain/efficient rainfall processes, while increasingly
diffluent flow aloft supports some training bands. As the upper
low settles a little further south, backing flow should shift the
heavy rain focus back toward the upslope regions of the Laurel
Highlands this afternoon into tonight.
Overall did not change QPF amounts very much with 50/50 blend of
the latest WPC guidance with the previous forecast. This should
mitigate some of the detail differences between individual model
QPF. Still calling for widespread 2-4" over the flood watch area
with locally 4-6" most likely across the east-facing slopes and
highest terrain. WPC QPF was based in large part on an ensemble of
HIRES guidance. What is a little concerning is the mean 24hr QPF
from the NCAR ensemble which shows the potential for 6+ inches.
Very dry antecedent conditions resulting in 3-6hr FFG values of 4+
inches along with below normal stream flows should help to mitigate
flooding to some extent, however if the higher end amounts are
realized flooding impacts/runoff issues could become more serious.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
The upper low continues to double back to MI on Friday before
slowly tracking eastward into the Lower Great Lakes over the
weekend. Strong E-SE LLJ and above normal PW along with
associated forcing on east/southeast side of upper low favors
scattered to numerous lighter rain showers through the period.
&&
.LONG TERM /MONDAY THROUGH WEDNESDAY/...
The trend for early next week is toward dry weather as the
stubborn upper low is finally is kicked to the northeast by
upstream amplifying trough over the Nation`s mid section. High
pressure should regain control of the large scale pattern. FWIW
the 29/00z GFS is much faster vs. the ECMWF with the projected
path of TC Matthew, with the system nearing the NC coast by
Thursday morning.
&&
.AVIATION /09Z THURSDAY THROUGH MONDAY/...
An increasingly moist easterly flow will overspread central Pa
early this morning, bringing low cigs and rain. Model soundings
and latest SREF output support predominantly IFR cigs through this
evening at the higher terrain airfields, including KBFD, KUNV,
KAOO and KJST. At the lower elevation airfields, predominantly
MVFR cigs are expected today at KIPT, KMDT and KLNS. However,
periodic IFR is likely this morning associated with bouts of
heavier rain.
Outlook...
Fri-Sat...Low cigs/showers likely, mainly w mtns.
Sun...AM low cigs possible.
Mon...Showers/cig reductions possible at KBFD.
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Friday morning for PAZ024>028-033>036-056-
063>065.
&&
$$
SYNOPSIS...Steinbugl
NEAR TERM...Steinbugl
SHORT TERM...Steinbugl
LONG TERM...Steinbugl
AVIATION...Fitzgerald
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
253 AM CDT Thu Sep 29 2016
.SHORT TERM (Today through Friday)...
Cold front passage progged for 14-15Z for AUS this morning should
shift winds to the north and re-enforce the dry atmosphere in
place over the region. While guidance values are not too gung-ho
about surface wind fields. There is some potential for 15-20 kt
winds to mix down to the surface from indication in the RAP
sounding analysis. Have notched up winds in the grids just a bit
over SuperBlend for this possibility.
Otherwise, biggest news in the short term will be how pleasant
Friday will be. Morning lows should fall to the low 50s and would
not be surprised to see upper 40s in a couple of low lying areas
such as river channels or valleys. Euro ensembles are showing some
members in the upper 40s for Kerrville/Fredericksburg and the
surrounding Hill Country, even Austin Bergstrom. While the
radiational cooling set up will be peachy, think the likelihood of
any place getting 40s will be best in the Hill Country.
&&
.LONG TERM (Friday Night through Wednesday)...
The weekend will shape up to be quite nice as well with morning
lows in the 50s and highs in the upper 70s and low 80s Saturday.
Gradual warming trend will begin Sunday as highs reach back into
80s throughout the CWA. H5 ridging will set up through the
beginning of next week but will be short lived as another closed
low from the Pacific Northwest pushes east through the Rocky
Mountain range.
By Wednesday morning, both GFS and ECMWF are indicating a cold
front being pushed into the state from the northwest. While
considerable differences exist in synoptic pattern, namely
negative tilting (ECMWF) vs positive tilting (GFS), both are
indicating a possible MCS passage with this next frontal system
Wednesday. Since considerable uncertainty in details exist, only
opted to go with slight chance PoPs for Day 7 for now. But for
now, no hazardous weather inclusion was made to the forecast.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 82 57 80 59 83 / 0 0 0 0 0
Austin Bergstrom Intl Airport 82 55 80 56 82 / 0 0 0 0 0
New Braunfels Muni Airport 84 56 81 57 83 / 0 0 0 0 0
Burnet Muni Airport 79 54 78 56 80 / 0 0 0 0 0
Del Rio Intl Airport 87 60 81 61 82 / 0 0 0 0 0
Georgetown Muni Airport 80 54 79 55 83 / 0 0 0 0 0
Hondo Muni Airport 87 57 81 57 83 / 0 0 0 0 0
San Marcos Muni Airport 83 55 80 57 81 / 0 0 0 0 0
La Grange - Fayette Regional 84 56 82 58 83 / 0 0 0 0 0
San Antonio Intl Airport 85 58 81 58 82 / 0 0 0 0 0
Stinson Muni Airport 86 59 81 59 84 / 0 0 0 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...Allen
Synoptic/Grids...TB3
Area Forecast Discussion
National Weather Service Wilmington NC
429 AM EDT Thu Sep 29 2016
.SYNOPSIS...
A cold front approaching from the west will slow down on Friday and
linger near or along the Carolina coast through this weekend. High
pressure will build in behind the front through early next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 330 am Thursday...SPC has a good portion of the ILM
CWA...mainly away from the immediate coast...in a marginal risk
today into this evening.
The cutoff low is progged to drop to central Kentucky by Friday
morning. Models indicate that this will be its furthest southern
push. Dynamics associated with mid-level vorts or s/w trofs,
interacting with the sfc cold front now across the central
Carolinas, and rotating around this upper low further aid the
development and persistence of convection today. Persistence,
meaning even after the days insolation has ceased the convection
will continue. This illustrated well by the convection that has
persisted across central NC during these pre-dawn Thu hours. In
general, have peaked POPs at 50 percent. But, depending on where
the current convection continues at xmit time, may go hier to
likely then drop it back down later this morning.
POPs have been continued along the immediate ILM CWA coast during
the pre-dawn Fri hrs due to convection aided by an upper s/w trof
tracking nearly due north around the periphery of the cutoff low.
The nocturnal development of convection over the Atl waters this
time of the year will also play a part.
As for temps, the European and NAM MOS Guidance, both have been
doing well with daytime highs based on the latest verification
stats for the local area for the past several days. For night time
Lows, the NAM Mos alone, is verifying the best.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 345 AM Thursday...To no surprise, the cutoff upper low and
mid-level vorts, like spokes on a bicycle tire, rotating around
it will be the driver of the sensible weather across the ILM CWA
this period. The good news, models have this cutoff/closed low
slowly opening up and lifting northward by the end of this period
as a result of the strong westerlies now able to move this upper
feature. At the sfc, the cold front will slowly make some progress
to the coast on Friday and on Saturday it basically stalls either
along the immediate coast or just offshore due to it becoming
parallel with the flow aloft. Therefore POPs will be confined
along the eastern 1/3rd of the ILM CWA and the adjacent Atlantic
waters thruout this period. The dry slot or tongue will affect
mainly the western 2/3rds of the ILM CWA helping to eliminate
POPs in that area. Could see hier POPs during the pre- dawn hrs
along the immediate coast during the pre- dawn Sat and Sun hours
due to the combined nocturnal development over the waters and any
mid- level vorts having either rotated around the cutoff low or
picked up off the Florida west coast or the northern Bahamas.
Max/Min temps to remain above normal, 1 to 2 categories, thruout
this period.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 3 AM Thursday...Large upper low finally lifting out to the
northeast early in the period. In its wake will be a weak pressure
gradient and a dissipating frontal boundary just offshore. A few
showers along this front may affect coastal locales but suspect that
most areas stay rain-free and seasonable. As the upper low begins to
interact with troughiness east of Canada rising surface pressures
advect into the eastern U.S. Tuesday and Wednesday. Should this flow
be NE then some lower dewpoints may creep into the Carolinas but
current progs show more ENE and likely preclude that. Building
heights aloft argue for not much in the way of meaningful precip
though a few sprinkles tough to rule out in the onshore low level
flow. This gradient could become pinched by Matthew and it may
become breezy locally by Wednesday if the quick GFS is correct.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
As of 06Z...Rather persistent storms just west of our area and the
HRRR wants to spread them all the way to the coast by daybreak. This
seems ambitious but have covered for this possibility with VC.
Better chance for predominant rain is at FLO and LBT. Then there may
be a break in the action before daytime heating causes isolated
storms to fire through the day as front remains stalled to our west.
By evening a large scale dry slot should be spreading into the area
shutting down any rainfall from SW to NE though a few may linger at
the coast.
EXTENDED OUTLOOK...Primarily VFR. Isolated to scattered afternoon
showers through much the period, although limited in strength and
coverage due to dry air aloft.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 330 AM Thursday...The sfc cold front to remain inland from
the coast during this period. That means a southerly wind will
continue across the local waters thruout this period. The sfc pg
to remain semi-tightened ahead of the cold front and should
produce 10 to 15 kt wind speeds...and could see occasional gusts
up to 20 kt, especially during the overnight period. Significant
seas will run a solid 3 foot. The spectral density charts indicate
that a pseudo easterly swell at 7 second periods, with an occasional
ese swell at 10 second periods, will both dominate the seas
spectrum. Wind driven waves will mesh on top of this e to ese
ground swell.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 400 AM Thursday...The movement of the cold front at a
snail`s pace will push it to the coast late Friday and possibly
either across the coastal waters or just offshore from Carolina
coastlines. The sfc pressure pattern will result in a S to SW wind
direction thruout this period. The sfc pg will remain
semi-tightened east of the cold front, with 10 to 15 kt speeds,
and somewhat relaxed in the vicinity of the cold front, with 10 kt
or less speeds. Significant seas to continue at 2 to 3 ft thruout
this period. The ese ground swell at 7 to 9 second periods will
mainly dominate the seas with local wind driven waves at 3 to 4
seconds on top. Expect convection thruout this period, with the
pre-dawn hrs thru daytime morning hrs of each day exhibiting the
hier pops during this period.
LONG TERM/SUNDAY THROUGH MONDAY/...
As of 3 AM Thursday...Weakening front along the coast Sunday will
keep winds very light though there is some uncertainty regarding
direction-though primarily onshore. Small wind chop combine w ESE
swell for a 2 to 3 ft dominant wave height. No significant changes
noted heading into Monday.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...None.
MARINE...None.
&&
$$
SYNOPSIS...MBB
NEAR TERM...DCH
SHORT TERM...DCH
LONG TERM...MBB
AVIATION...MBB
Area Forecast Discussion
National Weather Service Lincoln IL
300 AM CDT THU SEP 29 2016
.SHORT TERM...(Today and tonight)
ISSUED AT 300 AM CDT Thu Sep 29 2016
07z/2am water vapor imagery shows center of unseasonably deep upper
low over southern Indiana, with primary mid-level moisture plume
wrapping around the system from the Carolinas N/NW into southern
Michigan. As this slug of moisture continues to pivot around the
low, it is expected to spill into east-central Illinois today.
Latest radar imagery is showing numerous showers across northern
Indiana into northeast Illinois, and these should continue to spread
southwestward across the eastern half of the KILX CWA this morning.
Based on latest radar trends and HRRR forecast, have gone with
scattered showers everywhere east of the Illinois River today. Due
to the cloud cover and showers, temperatures will once again be held
below normal for this time of year, with readings mainly in the
middle to upper 60s. Showery conditions will continue tonight as
another vorticity max rotates around the parent upper low. Models
suggest showers will become more numerous after midnight,
particularly across the E/NE CWA. Overnight lows will be in the
middle 50s.
&&
.LONG TERM...(Friday through Wednesday)
ISSUED AT 300 AM CDT Thu Sep 29 2016
As has been advertised by the last few model runs, the upper low is
expected to drop southward into Kentucky today, then begin lifting
back northward on Friday. With the system expected to reach eastern
Illinois by late in the day, Friday appears to be the wettest day of
the forecast period with numerous showers across nearly the entire
CWA. Thanks to steepening lapse rates beneath the cold core aloft,
GFS MUCAPE values are forecast to reach the 800-1000J/kg range
across the eastern half of Illinois Friday afternoon. Have
therefore gone with likely PoPs for showers and isolated thunder
everywhere east of the Illinois River at that time. Scattered
showers will continue Friday night into Saturday as the low makes
only slow progress northward: however, 00z Sep 29 models agree that
the system will finally get shunted further northeast into the Great
Lakes by Sunday as a pronounced upper trough digs across the
western CONUS.
With the upper low departing and heights climbing substantially,
warming conditions are anticipated early next week. Temperatures
will reach the lower to middle 70s by Sunday, then will peak in the
upper 70s to lower 80s by Monday and Tuesday. As the western trough
approaches, it will eventually push a cold front into Illinois later
next week: however, the timing of the front is still in question due
to the evolution of Tropical Storm Matthew. GFS/ECMWF differ on the
speed of Matthew, with the ECMWF being considerably slower and
nearly stalling the system over the southern Bahamas late next week.
Trending toward the faster GFS, Matthew should track from Cuba N/NE
off the coast of North Carolina by Wed/Thu. This will tend to slow
the eastward progress of the approaching trough/surface front...and
delay rain chances in central Illinois. As a result, have gone with
dry condtions through Wednesday, with showers holding off until
Thursday.
&&
.AVIATION...(For the 06Z TAFS through 06Z Thursday night)
Issued at 1140 PM CDT Wed Sep 28 2016
Upper low in IN already spinning wave of showers from northeast IL
toward central sections. That should be the trend and overnight as
the low slides southward, expect mvfr cigs to rotate to the west
into east central parts of IL. Best change toward 12z and should
continue into afternoon. Pcpn should be scattered and mostly
light, so no drop in VSB. Gusty winds again should develop, with
gradient around low.
&&
.ILX Watches/Warnings/Advisories...
NONE.
&&
$$
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Goetsch
Area Forecast Discussion
National Weather Service Saint Louis MO
324 AM CDT THU SEP 29 2016
.SHORT TERM... (Through Late Tonight)
Issued at 323 AM CDT Thu Sep 29 2016
Main concern today will be clouds and a chance of showers. Most of
the area remains clear and any scattered showers are currently
northeast of the area over eastern Illinois. Do expect cloud that
are rotating around an upper low that is currently over Indiana to
spread westward today. RAP is showing low level moisture moving
westward today and there will be embedded vort centers moving on the
west side of the upper low. This will be conducive to both low
clouds overspreading the area and scattered showers developing over
south central Illinois. The chance of showers will continue into
tonight as a little more pronounced shortwave rounds the upper low
and moves across the region.
Went a bit closer to the warmer NAM MOS temperatures, particularly
over the west have of the CWA where I expect a bit more sun into the
afternoon before it turns mostly cloudy. Temperatures tonight will
be close to the agreeable MOS guidance which are supported by the
SREF mean surface temperatures.
Britt
.LONG TERM... (Friday through Wednesday)
Issued at 323 AM CDT Thu Sep 29 2016
The upper level low is still expected to wobble over the Ohio Valley
on Friday and Saturday before beginning to lift out Saturday night
and Sunday. GFS and NAM are continuing to show a well developed
moist conveyor belt on the northern side of the system. The
moisture feed remains pretty constant through Saturday with a tongue
of 8+ g/kg spec humidity traveling on the 295K isentropic surface
westward from the Atlantic across the Great Lakes and then wrapping
around the low into the Mid Mississippi Valley. Models continue to
spit QPF under this moisture feed...with highest amounts mainly east
of the Mississippi River. Based on QPF, it looks like the highest
PoPs should be Friday afternoon, and this makes good synoptic sense
as the low is forecast to meander back from the eastern
Kentucky/Indiana border to the central Illinois/Indiana border. This
will increase broad scale lift over our area and diurnal heating
should do the rest. Indeed, MOS PoPs are now up in likely and
categorical range along and east of the Mississippi for Friday. The
low drifts east on Saturday which will likely decrease the areal
coverage of precip...but with plenty of moisture still available and
probably a bit more diurnal heating would expect at least isolated
to widely scattered showers to develop along and east of the
Mississippi.
Low should be ejecting northeast on Sunday and even though the GFS
and ECMWF are kicking out an isolated hundredth or two of precip, I
think the day will be dry since the synoptic forcing will be rapidly
moving out of the area. Medium range for Monday through Wednesday
looks mostly dry under the influence of a strong ridge. Temperatures
should warm up to near seasonal normals...perhaps a bit above normal
Monday and Tuesday as southerly flow increases ahead of the next
trof. Timing on when that trof will move out of the Great Plains
into the Mississippi Valley is currently low confidence with the
ECMWF bringing it in Wednesday but the slower GFS holding back until
later next week. Think the compromise forecast with PoPs increasing
to slight chance/low chance Wednesday and temperatures warming well
above normal into the upper 70s to around 80 looks good for now.
Carney
&&
.AVIATION... (For the 06z TAFs through 06z Thursday Night)
Issued at 1141 PM CDT Wed Sep 28 2016
VFR conditions and NW surface winds will prevail at the TAF sites
for much of the valid period. Some MVFR CIGs expected for a period
Thursday morning and into midday over STL metro sites as diurnal
influences take place, but this should lift back into VFR by early
afternoon. Some gusts between 15-20kts anticipated during Thursday
afternoon over many sites.
SPECIFICS FOR KSTL: VFR and NW surface winds for much of the valid
period. Exceptions are a brief period of MVFR CIGs during late
Thursday morning and midday and again late Thursday night with
anticipated stratus moving in from the NE. Will begin CIGs at MVFR
level although some guidance is suggesting IFR.
TES
&&
.PRELIMINARY POINT TEMPS/POPS...
Saint Louis 69 57 70 58 / 20 20 50 20
Quincy 72 55 67 57 / 10 10 30 30
Columbia 72 54 69 56 / 5 5 10 20
Jefferson City 73 54 69 56 / 5 5 10 20
Salem 68 55 68 54 / 40 40 60 30
Farmington 67 55 66 54 / 10 10 30 20
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Omaha/Valley NE
313 AM CDT THU SEP 29 2016
.SHORT TERM...(today through Saturday)
Issued at 222 AM CDT THU SEP 29 2016
Latest water vapor imagery in addition to RAP 500 mb analysis
shows an upper ridge axis extending over the nation`s mid section.
This is sandwiched in between a trough to our west and a deep low
to our northeast. At the surface, a ridge axis extends from the
eastern Dakotas into eastern Nebrsaka. Some patchy fog cannot be
ruled out this morning with low dewpoint depressions, light winds
and clear skies. Otherwise, dry weather is expected to continue
for the forecast area through the weekend with temperatures close
to normal for this time of year as the upper low to our northeast
continues to spin south of the Great Lakes.
.LONG TERM...(Saturday night through Wednesday)
Issued at 222 AM CDT THU SEP 29 2016
By Saturday night, the previous mentioned upper low, having moved
only slightly, will begin to finally eject northeast into the
eastern Great Lakes region while the west coast trough continues
to deepen and shift east. Ahead of the west coast trough, strong
southerly flow will bring increasing moisture to the Central
Plains toward early next week. The next chance of
showers/thunderstorms looks to hold off until late Monday or early
Tuesday in warm air advection regime. Scattered chances will
continue into Wednesday before a cold front slides through the
area sometime mid week.
&&
.AVIATION...(06Z TAFS for KOFK...KLNK and KOMA.)
Issued at 1154 PM CDT WED SEP 28 2016
VFR conditions through the period save for some patchy fog
possible. Included mvfr conditions at KOMA and lower visibilities
could develop.
&&
.OAX Watches/Warnings/Advisories...
NE...None.
IA...None.
&&
$$
SHORT TERM...Kern
LONG TERM...Kern
AVIATION...Zapotocny
Area Forecast Discussion
National Weather Service Pittsburgh PA
435 AM EDT Thu Sep 29 2016
.SYNOPSIS...
Upper level low pressure will bring rain to our region for the
rest of the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Models in good agreement in dropping upper low into western
Kentucky today and stalling it there through tonight. Several
issues to deal with during the near term period, including QPF,
thunderstorm potential, and wind gusts tonight.
Heavier rainfall totals to this point have occurred along the
eastern slopes in Garrett/Tucker Counties, as well as in a small
band from western Fayette into Allegheny, with 0.5 to 1.0 inch of
rain. Expect best focus for precip will shift to the north of
Pittsburgh and along the eastern slopes as the morning progresses,
due to shifting of best upper diffluence and continued upslope
flow. This is similar to HRRR depiction. Accordingly, lesser
coverage is foreseen for southeast Ohio into northern West
Virginia. Coverage should improve this afternoon in these areas as
a few breaks in the clouds allow for instability showers and a few
thunderstorms to develop. Cannot rule out a strong storm or two
across the south given the high levels of deep shear, and even
some small hail is possible. However, overall low levels of
instability should keep this threat isolated at best.
Still concerned about potential QPF levels along and just west of the
eastern ridges as the Atlantic moisture tap continues through
tonight. The period for heaviest rain appears to be from late this
afternoon through 06Z tonight when moisture is deepest. Considered
issuance of a small flood watch for several counties in our
southeast. Given the dry conditions before tonight, the relative
underperformance of QPF to this point, and the apparent lull in
activity this morning, have elected to hold off on issuance at
this time, thinking that expected rainfall will fall over a long
enough period to prevent widespread issues. Will continue the HWO
mention and monitor the situation closely.
Final issue to consider is potential wind gust issues tonight
along western slopes of the ridges. With potential stable layer
above ridgetops and winds oriented favorably with ridgelines,
there is the potential for strong downsloping winds. Kept gusts
below advisory level for now, but this will also need to be
monitored.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
Rain and gusty winds will linger through Saturday as the
nearly stationary mature low pressure system gradually fills. A
strong 60kt+ jet at 850mb is progged to stream across our southeast
ridges through Friday morning. Still some questions as to the
orthogonal flow and just how much of this wind will be able to
break to the surface, so at the moment, the near Advisory gusts
and HWO mention were maintained from previous forecast.
Strong downsloping flow will continue through the day Friday as the
parent low moves very little. This, along with the deep Atlantic
moisture feed and convergence zone lifting north will result in a
relative minima in shower activity just west of the ridges through
center of the forecast area. This rain shadow effect is reflected in
most operational model qpf fields and PoPs and WPC collaborated qpf
have been trimmed back accordingly.
As the low dislodges and slowly creeps northward Saturday, the dry
slot wrapping around the eastern edge of the circulation will push
into our area. This will bring an end to any organized rain bands,
leaving only scattered, light rain showers mainly across the north.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Lingering low pressure system will slowly drift over the southern
Great Lakes Sunday into Monday. While this will keep rain chances in
the forecast across the north, the aforementioned dry air will erode
residual moisture. By Tuesday, the low will finally move east of the
area, and high pressure will build into our west. This will bring a
return to drier and warmer conditions with temperatures returning to
above-average through the end of the week.
&&
.AVIATION /08Z THURSDAY THROUGH MONDAY/...
An upper low will continue to affect our region through the next
few days. MVFR ceilings have developed at several terminals
tonight, but some clouds in the cloud deck remain. These should
fill with time and MVFR ceiling are expected in the mean through
the TAF period. Rain chances will increase with time, especially
along the ridges and north of PIT. Some periods of IFR are
possible, especially in any heavier rain. Wind gusts of 20 to 25
knots will be possible during the day.
.OUTLOOK /THURSDAY NIGHT THROUGH SUNDAY/...
Periodic restrictions can be expected into the weekend as the
upper level low lingers, then slow lifts north of the region.
&&
.PBZ WATCHES/WARNINGS/ADVISORIES...
MD...None.
OH...None.
PA...None.
WV...None.
&&
$$
Area Forecast Discussion
National Weather Service Blacksburg VA
322 AM EDT Thu Sep 29 2016
.SYNOPSIS...
A strong upper level area of low pressure will remain just west of
the mountains today into Friday. This system will combine with a
residual stationary front across the region to produce periods of
showers and thunderstorms today into Friday night. The low will
move northeast, away from the region, resulting in drier weather
this weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 240 AM EDT Thursday...
Appears another active day in store espcly this afternoon as the
upper low to the northwest digs toward the Tennessee Valley and
another impulse aloft rotates through from the southwest. This looks
to again play tag with the stalled surface low and occluded boundary
stuck along the Blue Ridge. Bands of added convection likely to take
shape across the eastern half as this occurs per latest Cam
solutions with coverage rotating north/northwest into northern
sections through the evening. However exactly where this takes place
and how fast in question given early showers, and idea that this
initial axis will shift east, followed by low clouds that may tend
to limit instability later on within low level easterly flow. Think
best chances of deeper convection will occur just south of the
boundary/triple point and perhaps even out west where will have a
band under the upper low arriving late. Although lapses likely to be
weaker today unless more heating occurs, added cooling aloft and
deeper low level southeast flow turning southwest aloft while
strengthening supports added severe hail/wind potential. This espcly
along/southeast of the boundary near Highway 460 where shear
parameters best.
Thus after a likely early morning lull as supported by the latest
HRRR expect enough coverage to keep overall likely/cat pops in all
except the far sw where a weak dry slot may hold. Highest QPF looks
to also reside across the easternmost counties with this axis
swinging back toward the Virginia Highlands later today. May add
Rockbridge to the watch given pockets of heavier rainfall overnight
and possible added training bands today. Highs mostly 70s although
could get to around 80 southeast if more sunshine develops, while
some spots across the north may get stuck in the 60s if clouds
persist.
Upper low should begin to pivot slowly north/northeast overnight
allowing the eastern conveyor belt of deep moisture/convergence to
lift a bit farther to the northeast late ahead of the residual
surface front. This may also push somewhat drier air aloft into
western sections late as the weak surface low along the Blue Ridge
retrogrades back westward, and a secondary cold front edges east
across the far west. Appears loss of instability should again help
reduce thunder chances after this evening but lingering heavy rain
threat likely to continue at least northeast third through late
tonight. Therefore keeping a gradient of likely or higher pops
mainly along/east of the Blue Ridge overnight and chances elsewhere
given expected slower exodus of deeper moisture. Low temps mainly
50s mountains to mid 60s out east.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 230 AM EDT Thursday...
A very large closed low will wobble over the southern Ohio Valley
through Saturday night. Through each period, precipitation coverage
will become smaller and smaller as dry air gets wrapped into this
low. Dry air will start moving over the the southern Appalachains
Friday morning, then works north through the day. Rain showers will
begin to taper off from south to north behind a short wave axis,
finally exiting the Alleghany Highlands and the Hill City of
Lynchburg late Friday evening. Even though mid and high levels will
remain relatively dry Saturday, low level moisture and afternoon
heating may produce a few shallow dark base clouds and a few
showers. Overall coverage of showers and measurable rain will be
less than 10 percent Saturday afternoon.
Temperatures will remain seasonal Friday into the weekend with highs
ranging in the 70s, some 60s along ridge tops and lows into the 50s.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 320 PM EDT Wednesday...
Closed upper low will lift northeast and reach the St. Lawrence
river valley by Sunday night. Then, the low center will open up
and weaken as it moves across New England Monday and moves into
the Atlantic ocean on Tuesday.
The exact evolution of the large scale patterns will affect the
eventual track of what is forecasted by NHC to be Hurricane Matthew.
The storm may threaten the southeast coast next week. This is being
monitored by the NHC and WPC.
For much of the extended ISC grids leaned towards WPC which was a
blend of the 00Z GFS/GEFS MEAN/ECMWF ENS MEAN. Temperatures will
start cooler for Saturday with continued improvement as
precip/cloudcover comes to an end, then temperatures begin to
moderate Sunday into Wednesday.
&&
.AVIATION /07Z THURSDAY THROUGH MONDAY/...
As of 1257 AM EDT Thursday...
Bands of convection persist across parts of the region tonight,
with the best coverage along/east of the Blue Ridge. Expect
lingering coverage to perhaps impact all locations excluding KBLF
overnight but too iffy to include much more than a VCSH or tempo
group through daybreak. Otherwise looking at VFR to MVFR cigs with
pockets of IFR mainly around KLYH and where showers/clouds may
fade allowing for fog formation to take shape.
As an upper low moves south of the Great Lakes Thursday...a cold
front will approach the Appalachians from the west. This front
will merge with a stationary low pressure system over Virginia on
Thursday. This will result in added rounds of showers and storms
espcly during the afternoon with perhaps a lull during the
morning. Appears cigs may also rise to MVFR to VFR by midday
before convection redevelops espcly in a band across the east and
another with the front approaching from the west. Still uncertain
with overall coverage but given high probability will include a
prevailing group in spots with vicinity mention elsewhere.
Extended aviation discussion...
A deep upper low will remain over the Ohio and Tennessee Valleys
through Friday night. This will keep variable clouds, MVFR cigs,
and periods of -SHRA across the region through much of the period.
Should finally see VFR return during Saturday and continue into Monday
as the upper low lifts north and weak high pressure builds in.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...Flash Flood Watch through this afternoon for VAZ024-035-
044>047-058-059.
NC...None.
WV...None.
&&
$$
SYNOPSIS...AMS/JH
NEAR TERM...JH
SHORT TERM...RCS
LONG TERM...KK
AVIATION...AMS/JH/WP
Area Forecast Discussion...UPDATED
National Weather Service Albuquerque NM
532 AM MDT THU SEP 29 2016
.AVIATION...
12Z TAF CYCLE
-SHRA and a few -TSRA have moved into western NM early this AM
and are quickly moving north. These showers will likely continue
thru mid morning, then there may be a short lull before the
afternoon round of thunderstorms develop. More widespread coverage
of storms is expected today compared to yesterday. Both KFMN and
KGUP have high chances of being impacted. Brief MVFR cigs will be
possible as well as gusty outflow winds. Confidence remains low
regarding how far east the convection will make it. Backed off on
timing of VCSH at KABQ and KAEG, but latest HRRR suggests it may
be even later, if at all.
34
&&
.PREV DISCUSSION...310 AM MDT THU SEP 29 2016...
.SYNOPSIS...
Ridge of high pressure is just east of NM while a weak short wave
trough has lifted northeast into the Great Basin. A weak low off
the coast of Baja CA is what`s left of tropical depression Rosyln.
It will lift northeast and dissolve within the southwest flow
aloft. Today and Friday will be the most active days of the
forecast period. Westerly flow aloft will bring drier into the
state for the weekend and the start of the Balloon Fiesta. A
closed low and deep trough will bring increasing winds and cooler
temperatures for the first half of next week.
&&
.DISCUSSION...
A few light showers continue to the west of the continental divide
early this morning. They will continue to develop this morning and
some thunderstorms will join in this afternoon and evening. Bulk
of today`s activity will be over the western higher terrain. As a
potent storm system moves toward the Pacific Northwest Friday,
the moisture plume will move east, with central and northeast
areas receiving some precipitation Friday and Friday night.
A weak high pressure ridge will set up over NM this weekend. A few
lingering showers will continue over the western and central
mountains Saturday, but Sunday should be rain free across all of
northern and central NM.
The deep low will move into northern CA Sunday night, turn east
across the Great Basin Monday then rapidly lift northeast Tuesday.
The trough axis will cross NM Tuesday, delivering gusty winds and
much cooler temperatures. Showers are possible ahead of the trough
Sunday night into Monday night. This includes the potential for
some strong thunderstorms near the TX border late Monday as the
surface cold front associated with the upper trough arrives.
Tuesday will be dry, but brisk and cool.
Wednesday and Thursday will be mostly dry with less wind and some
increase in temperatures. A weak secondary short wave trough may
drop southeast into NM Wednesday if the GFS is right. But this
would only produce some rain showers over the northern mountains
Wednesday, and snow showers Wednesday night. CHJ
&&
.FIRE WEATHER...
Still looking for another uptick in precipitation across western NM
today, generally along and west of the ContDvd. Dewpoints have
already increased into the 50s, which bodes well for wetting rains,
as opposed to previous days with dewpoints in the 30s and low 40s.
Local WRF model shows some precip making it into the Rio Grande
Valley this evening, but do not think it would be much more than
sprinkles if it does so. Otherwise, batch of high clouds
overspreading the area early this morning should break up this
afternoon, but low/mid level cloud deck will persist across the
west. High temperatures will generally be a bit cooler today, but
near normal. Excellent relative humidity recoveries are expected
tonight across the west, with good recoveries elsewhere.
The plume of moisture across the west today will gradually shift
east on Friday. High terrain areas will have the best chance of
precip, and some wetting rains are possible.
The drying trend will begin on Saturday across the Land of
Enchantment. The NAM is less robust drying it out on Saturday, and
actually develops some light qpf south of I-40 Sat aftn. Not
totally sold on this scenario and may be more virga than anything
else. All other operational models remain drier. The weak ridging
over the state on Saturday should shift east on Sunday allowing for
even drier air to move in and completely squash precip chances.
All eyes are then on the next Pacific storm system early next week
diving into the Great Basin Sunday, then shifting eastward across
the central Rockies Monday and Tuesday. Looks like the main concern
will be an increase in wind on Monday areawide, with breezy
conditions continuing on Tuesday across the east following a cold
frontal passage. Critical fire weather conditions will be possible
on Monday if humidities can drop low enough, but current forecast
has them just above critical criteria. Otherwise, should see a 7 to
10 degree temperature drop going from Monday to Tuesday, which will
result in below normal temps Tuesday. Dewpoints will lower
significantly following the frontal passage, but the question
remains if there will be precip along the front Monday aftn and
night. ECMWF has better moisture in place before the front arrives,
thus does break out some modest precipitation along the front. The
GFS holds off on precip until the front reaches eastern NM where the
best moisture resides.
Generally good or better vent rates are in store today, though
spotty areas of poor ventilation are still possible on Friday across
the north and west. Generally improving vent rates thereafter as
winds increase. 34
&&
.ABQ WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
636 AM CDT Thu Sep 29 2016
.AVIATION.../12Z TAF CYCLE/
VFR conditions will prevail through the next 24-30 hours with only
high passing clouds. A dry front will shift through all TAF sites
today and bring stronger north winds. Sustained winds will be near
10-15 knots and an occasional gust to 20-24 knots could be
possible, especially for KAUS. Wind strength will be slightly
lower at KSAT/KSSF/KDRT. Winds will diminish after sunset this
evening to near 5 knots or less.
&&
.PREV DISCUSSION... /ISSUED 253 AM CDT Thu Sep 29 2016/
SHORT TERM (Today through Friday)...
Cold front passage progged for 14-15Z for AUS this morning should
shift winds to the north and re-enforce the dry atmosphere in
place over the region. While guidance values are not too gung-ho
about surface wind fields. There is some potential for 15-20 kt
winds to mix down to the surface from indication in the RAP
sounding analysis. Have notched up winds in the grids just a bit
over SuperBlend for this possibility.
Otherwise, biggest news in the short term will be how pleasant
Friday will be. Morning lows should fall to the low 50s and would
not be surprised to see upper 40s in a couple of low lying areas
such as river channels or valleys. Euro ensembles are showing some
members in the upper 40s for Kerrville/Fredericksburg and the
surrounding Hill Country, even Austin Bergstrom. While the
radiational cooling set up will be peachy, think the likelihood of
any place getting 40s will be best in the Hill Country.
LONG TERM (Friday Night through Wednesday)...
The weekend will shape up to be quite nice as well with morning
lows in the 50s and highs in the upper 70s and low 80s Saturday.
Gradual warming trend will begin Sunday as highs reach back into
80s throughout the CWA. H5 ridging will set up through the
beginning of next week but will be short lived as another closed
low from the Pacific Northwest pushes east through the Rocky
Mountain range.
By Wednesday morning, both GFS and ECMWF are indicating a cold
front being pushed into the state from the northwest. While
considerable differences exist in synoptic pattern, namely
negative tilting (ECMWF) vs positive tilting (GFS), both are
indicating a possible MCS passage with this next frontal system
Wednesday. Since considerable uncertainty in details exist, only
opted to go with slight chance PoPs for Day 7 for now. But for
now, no hazardous weather inclusion was made to the forecast.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 82 57 80 59 83 / 0 0 0 0 0
Austin Bergstrom Intl Airport 82 55 80 56 82 / 0 0 0 0 0
New Braunfels Muni Airport 84 56 81 57 83 / 0 0 0 0 0
Burnet Muni Airport 79 54 78 56 80 / 0 0 0 0 0
Del Rio Intl Airport 87 60 81 61 82 / 0 0 0 0 0
Georgetown Muni Airport 80 54 79 55 83 / 0 0 0 0 0
Hondo Muni Airport 87 57 81 57 83 / 0 0 0 0 0
San Marcos Muni Airport 83 55 80 57 81 / 0 0 0 0 0
La Grange - Fayette Regional 84 56 82 58 83 / 0 0 0 0 0
San Antonio Intl Airport 85 58 81 58 82 / 0 0 0 0 0
Stinson Muni Airport 86 59 81 59 84 / 0 0 0 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...Allen
Synoptic/Grids...TB3
Area Forecast Discussion
National Weather Service Grand Rapids MI
953 AM EDT THU SEP 29 2016
LATEST UPDATE...
Marine
.SYNOPSIS...
Issued at 323 AM EDT Thu Sep 29 2016
Low pressure will continue to spin near and over Lower Michigan
through the week and into the weekend. This will bring mostly
cloudy weather with periods of showers and a few thunderstorms.
&&
.UPDATE...
Issued at 902 AM EDT Thu Sep 29 2016
Based on the latest radar trends and looking at an ensemble of
the HRRR, HRRRX, and RAP model (using time lagged ensembles) I
redefined the rain area farther north (by about a row of
counties) for today and also updated the QPF to match.
There is some through about flood advisories but at this point I
think the rain band near I-94 is going to break up enough over the
next few hours so that will not be a big issue. Jackson County has
had around an inch of rain so that would be the most venerable.
Again I think that rain band should be moving out of there in the
next few hours. Overall this still will have to be watched.
&&
.SHORT TERM...(Today through Saturday)
Issued at 323 AM EDT Thu Sep 29 2016
Upper cutoff low spins across the Ohio Valley then moves north
back into Lower Michigan by the end of the period. Strong easterly
flow including low level jet will tap into tropical moisture
plume moving up the east coast by Thursday night. Showers will
become more widespread and persist into Friday before beginning to
taper off as the occluded low moves into the forecast area.
Marginally steep lapse rates late Thursday into Saturday make
diurnal enhancement of thunderstorms possible each day. The
persistent nature of the flow regime and the presence of tropical
moisture feeding in will mean that excessive rains are possible
and this will have to be monitored closely.
.LONG TERM...(Saturday night through Wednesday)
Issued at 323 AM EDT Thu Sep 29 2016
The upper low will continue to linger over our region Saturday night
through Sunday and bring extensive cloud cover and scattered
showers.
The pattern should finally become more progressive Sunday night
into early next week when the upper level low will finally
move east of our region as upper ridging builds in from the
west.
As a result fair weather will finally return early next week
with seasonably mild temperatures reaching the lower to perhaps
middle 70`s by next Mon/Tue.
&&
.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 725 AM EDT Thu Sep 29 2016
Areas of IFR can be expected today and tonight with rain showers
and ceilings around 700 to 900 feet AGL. East winds will be around
10 knots with gusts to 20 knots this afternoon.
&&
.MARINE...
Issued at 953 AM EDT Thu Sep 29 2016
We have added waterspouts to the forecast for the nearshore waters
south of Whitehall for today. This is where most of the showers
that could produce waterspouts will be, closer to the center of
the low, and under the cold pool aloft. Most of them should be
offshore with the offshore wind, but it is still enough of a
threat to mention.
&&
.HYDROLOGY...
Issued at 140 PM EDT Tue Sep 27 2016
River levels are around normal for this time of year. Lake enhanced
rain showers are possible through Wednesday. Rain showers continue
to be possible into Sunday. Rainfall totals into the weekend will
range from a half inch up to an inch and a half. Rivers and streams
should remain below bankfull through the weekend.
&&
.GRR Watches/Warnings/Advisories...
MI...None.
LM...Small Craft Advisory until 6 PM EDT Friday for LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...Ostuno
SHORT TERM...Ostuno
LONG TERM...Laurens
AVIATION...Ostuno
HYDROLOGY...63
MARINE...NJJ
Area Forecast Discussion
National Weather Service Wilmington NC
1055 AM EDT Thu Sep 29 2016
.SYNOPSIS...
A cold front approaching from the west will slow down on Friday and
linger near or along the Carolina coast through this weekend.
Periods of showers and thunderstorms are possible along this
front. High pressure will build in behind the front through early
next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM Thursday...Very active morning is expected to
transition to a busy afternoon as thunderstorms continue to develop
and expand across the CWA. A Flash Flood Watch has been issued for
the ILM NC counties, and is in effect until 10 PM.
Deep cutoff upper low across IN/OH continues to spin mostly in
place, while pieces of vort energy, "spokes," rotate around the main
cutoff. At the same time, much drier air is evident on WV imagery
rotating through GA and into SC, but this will be impeded in much
eastern progress, so the eastern half of the CWA will remain quite
wet today. Thunderstorms with very heavy rainfall have been ongoing
since daybreak, and have expanded back to the SW through late
morning while motion remains quick to the NE. While individual cells
move quickly NE, backbuilding and training is forecast, hence the
recently issued FFA. Freezing levels near 14 kft combined with
moderate MUCape is creating efficient warm rain processes, and with
PWATS around 1.7 inches, this is coalescing as very heavy rainfall.
SPC Mesoanalysis shows good wind/moisture convergence at 850mb,
which combined with moderate diffluence aloft on the lee side of the
upper low, is allowing strong lift, which will only increase this
aftn with heating and increasing instability.
While periods of heavy rainfall leading to flash flooding is likely,
and is supported by recent ARW and RAP guidance, the exact location
for any significant rain may be difficult to pinpoint. Expect a rain
axis to continue where it currently exists along the best low-level
wind convergence and along the moisture axis from east to west, but
otherwise areas of thunderstorms with heavy rainfall will develop
across eastern portions of the CWA through this evening. The "fly in
the ointment" to this is a clearly evident hybrid outflow/cold front
sinking southward across the Pee Dee this morning. While this
boundary may initially force updrafts in the warm sector due to
surface convergence, air behind it is cooler and more stable than to
the SE of it, and may be limiting both to temperatures and rainfall
potential. However, deep southerly flow through the column should
eventually slow and stall the progress of this boundary, causing it
to lift back to the north this aftn. A very complex forecast
however, and bust potential even in the near term is high for temps
and precip near this wavering boundary.
Highs today are expected to rise into the low to mid 80s, but may
fluctuate quite a bit in heavy rainfall and depending on where that
front wavers this aftn. While convection is forecast to wane after
dark, warm southerly flow will persist, keeping mins from falling
out of the low 70s near the coast, upper 60s inland in the drier air.
&&
.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 345 AM Thursday...To no surprise, the cutoff upper low and
mid-level vorts, like spokes on a bicycle tire, rotating around
it will be the driver of the sensible weather across the ILM CWA
this period. The good news, models have this cutoff/closed low
slowly opening up and lifting northward by the end of this period
as a result of the strong westerlies now able to move this upper
feature. At the sfc, the cold front will slowly make some progress
to the coast on Friday and on Saturday it basically stalls either
along the immediate coast or just offshore due to it becoming
parallel with the flow aloft. Therefore POPs will be confined
along the eastern 1/3rd of the ILM CWA and the adjacent Atlantic
waters thruout this period. The dry slot or tongue will affect
mainly the western 2/3 of the ILM CWA helping to eliminate POPs
in that area. Could see hier POPs during the pre- dawn hrs along
the immediate coast during the pre- dawn Sat and Sun hours due to
the combined nocturnal development over the waters and any mid-
level vorts having either rotated around the cutoff low or picked
up off the Florida west coast or the northern Bahamas. Max/Min
temps to remain above normal, 1 to 2 categories, thruout this
period.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 3 AM Thursday...Large upper low finally lifting out to the
northeast early in the period. In its wake will be a weak pressure
gradient and a dissipating frontal boundary just offshore. A few
showers along this front may affect coastal locales but suspect that
most areas stay rain-free and seasonable. As the upper low begins to
interact with troughiness east of Canada rising surface pressures
advect into the eastern U.S. Tuesday and Wednesday. Should this flow
be NE then some lower dewpoints may creep into the Carolinas but
current progs show more ENE and likely preclude that. Building
heights aloft argue for not much in the way of meaningful precip
though a few sprinkles tough to rule out in the onshore low level
flow. This gradient could become pinched by Matthew and it may
become breezy locally by Wednesday if the quick GFS is correct.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
As of 12Z...A surface boundary is noted N of KILM to between
KFLO/KLBT. Showers/thunderstorms are sct S of the boundary with the
best coverage N of the boundary.
Showers appear likely at all terminals into the afternoon, with
VCTS this morning KLBT and this afternoon at the coastal
terminals. MVFR most likely N of the boundary at KLBT this
morning, with VFR/TEMPO MVFR/IFR elsewhere associated with
precipitation. IFR is too brief to mention in TAFS. Could be a
decrease in coverage as the day progresses and some drier air
intrudes. MVFR should become less likely at KLBT EARLY afternoon
as the surface boundary shifts N. There is a chance showers could
re-develop KLBT-KFLO around midnight Z.
EXTENDED OUTLOOK...Primarily VFR. Isolated to scattered afternoon
showers through much the period, although limited in strength and
coverage due to dry air aloft.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 1000 AM Thursday...Surface cold front will remain inland
today, keeping predominantly S/SW winds across the waters. Wind
speeds have been 10-15 kts this morning, and little change in speed
is forecast, although occasional gusts up to 20kts are possible,
especially this evening and tonight. Seas will remain a nearly
uniform 3 ft, thanks to a 10-11 sec SE swell and 5-6 sec southerly
wind wave.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 400 AM Thursday...The movement of the cold front at a
snail`s pace will push it to the coast late Friday and possibly
either across the coastal waters or just offshore from Carolina
coastlines. The sfc pressure pattern will result in a S to SW wind
direction thruout this period. The sfc pg will remain
semi-tightened east of the cold front, with 10 to 15 kt speeds,
and somewhat relaxed in the vicinity of the cold front, with 10 kt
or less speeds. Significant seas to continue at 2 to 3 ft thruout
this period. The ese ground swell at 7 to 9 second periods will
mainly dominate the seas with local wind driven waves at 3 to 4
seconds on top. Expect convection thruout this period, with the
pre-dawn hrs thru daytime morning hrs of each day exhibiting the
hier pops during this period.
LONG TERM/SUNDAY THROUGH MONDAY/...
As of 3 AM Thursday...Weakening front along the coast Sunday will
keep winds very light though there is some uncertainty regarding
direction-though primarily onshore. Small wind chop combine w ESE
swell for a 2 to 3 ft dominant wave height. No significant changes
noted heading into Monday.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...Flash Flood Watch until 10 PM EDT this evening for NCZ087-096-
099-105>110.
MARINE...None.
&&
$$
SYNOPSIS...MBB
NEAR TERM...JDW
SHORT TERM...DCH
LONG TERM...MBB
AVIATION...MRR
MARINE...
Area Forecast Discussion
National Weather Service Lincoln IL
949 AM CDT THU SEP 29 2016
.UPDATE...
Issued at 949 AM CDT Thu Sep 29 2016
Upper low currently centered near Louisville KY and will continue
to drift southward through the afternoon. Bands of showers
continue to rotate southwestward into the CWA around this low,
with earlier showers mainly along I-55 and the next band to target
areas between I-55 and I-57. Some sharper mid-level lapse rates
may contribute to a few thunderstorms at times, but mostly general
rain showers will be the rule. Areas near and west of the Illinois
River will remain dry most of the time.
Recent updates were mainly to reflect PoP trends, increasing them
in some areas. Temperatures are largely on track.
&&
.SHORT TERM...(Today and tonight)
ISSUED AT 300 AM CDT Thu Sep 29 2016
07z/2am water vapor imagery shows center of unseasonably deep upper
low over southern Indiana, with primary mid-level moisture plume
wrapping around the system from the Carolinas N/NW into southern
Michigan. As this slug of moisture continues to pivot around the
low, it is expected to spill into east-central Illinois today.
Latest radar imagery is showing numerous showers across northern
Indiana into northeast Illinois, and these should continue to spread
southwestward across the eastern half of the KILX CWA this morning.
Based on latest radar trends and HRRR forecast, have gone with
scattered showers everywhere east of the Illinois River today. Due
to the cloud cover and showers, temperatures will once again be held
below normal for this time of year, with readings mainly in the
middle to upper 60s. Showery conditions will continue tonight as
another vorticity max rotates around the parent upper low. Models
suggest showers will become more numerous after midnight,
particularly across the E/NE CWA. Overnight lows will be in the
middle 50s.
.LONG TERM...(Friday through Wednesday)
ISSUED AT 300 AM CDT Thu Sep 29 2016
As has been advertised by the last few model runs, the upper low is
expected to drop southward into Kentucky today, then begin lifting
back northward on Friday. With the system expected to reach eastern
Illinois by late in the day, Friday appears to be the wettest day of
the forecast period with numerous showers across nearly the entire
CWA. Thanks to steepening lapse rates beneath the cold core aloft,
GFS MUCAPE values are forecast to reach the 800-1000J/kg range
across the eastern half of Illinois Friday afternoon. Have
therefore gone with likely PoPs for showers and isolated thunder
everywhere east of the Illinois River at that time. Scattered
showers will continue Friday night into Saturday as the low makes
only slow progress northward: however, 00z Sep 29 models agree that
the system will finally get shunted further northeast into the Great
Lakes by Sunday as a pronounced upper trough digs across the
western CONUS.
With the upper low departing and heights climbing substantially,
warming conditions are anticipated early next week. Temperatures
will reach the lower to middle 70s by Sunday, then will peak in the
upper 70s to lower 80s by Monday and Tuesday. As the western trough
approaches, it will eventually push a cold front into Illinois later
next week: however, the timing of the front is still in question due
to the evolution of Tropical Storm Matthew. GFS/ECMWF differ on the
speed of Matthew, with the ECMWF being considerably slower and
nearly stalling the system over the southern Bahamas late next week.
Trending toward the faster GFS, Matthew should track from Cuba N/NE
off the coast of North Carolina by Wed/Thu. This will tend to slow
the eastward progress of the approaching trough/surface front...and
delay rain chances in central Illinois. As a result, have gone with
dry condtions through Wednesday, with showers holding off until
Thursday.
&&
.AVIATION...(For the 12Z TAFS through 12Z Friday morning)
Issued at 651 AM CDT Thu Sep 29 2016
Lower clouds and scattered showers continue to rotate around the
upper level system sitting over IN. Unfortunately do not see this
flow pattern changing very much, so scattered shower will continue
to impact flyers outside. Some cig heights are VFR, while other
sites are already below that level. Believe all sites will be MVFR
or less during the day. Winds will be northerly with gusts already
occurring. Gusts will increase more during the afternoon, and I do
believe I saw of picture of one earlier today.
&&
.ILX Watches/Warnings/Advisories...
NONE.
&&
$$
UPDATE...Geelhart
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Auten
Area Forecast Discussion...Updated Aviation
National Weather Service Saint Louis MO
653 AM CDT THU SEP 29 2016
.SHORT TERM... (Through Late Tonight)
Issued at 323 AM CDT Thu Sep 29 2016
Main concern today will be clouds and a chance of showers. Most of
the area remains clear and any scattered showers are currently
northeast of the area over eastern Illinois. Do expect cloud that
are rotating around an upper low that is currently over Indiana to
spread westward today. RAP is showing low level moisture moving
westward today and there will be embedded vort centers moving on the
west side of the upper low. This will be conducive to both low
clouds overspreading the area and scattered showers developing over
south central Illinois. The chance of showers will continue into
tonight as a little more pronounced shortwave rounds the upper low
and moves across the region.
Went a bit closer to the warmer NAM MOS temperatures, particularly
over the west have of the CWA where I expect a bit more sun into the
afternoon before it turns mostly cloudy. Temperatures tonight will
be close to the agreeable MOS guidance which are supported by the
SREF mean surface temperatures.
Britt
.LONG TERM... (Friday through Wednesday)
Issued at 323 AM CDT Thu Sep 29 2016
The upper level low is still expected to wobble over the Ohio Valley
on Friday and Saturday before beginning to lift out Saturday night
and Sunday. GFS and NAM are continuing to show a well developed
moist conveyor belt on the northern side of the system. The
moisture feed remains pretty constant through Saturday with a tongue
of 8+ g/kg spec humidity traveling on the 295K isentropic surface
westward from the Atlantic across the Great Lakes and then wrapping
around the low into the Mid Mississippi Valley. Models continue to
spit QPF under this moisture feed...with highest amounts mainly east
of the Mississippi River. Based on QPF, it looks like the highest
PoPs should be Friday afternoon, and this makes good synoptic sense
as the low is forecast to meander back from the eastern
Kentucky/Indiana border to the central Illinois/Indiana border. This
will increase broad scale lift over our area and diurnal heating
should do the rest. Indeed, MOS PoPs are now up in likely and
categorical range along and east of the Mississippi for Friday. The
low drifts east on Saturday which will likely decrease the areal
coverage of precip...but with plenty of moisture still available and
probably a bit more diurnal heating would expect at least isolated
to widely scattered showers to develop along and east of the
Mississippi.
Low should be ejecting northeast on Sunday and even though the GFS
and ECMWF are kicking out an isolated hundredth or two of precip, I
think the day will be dry since the synoptic forcing will be rapidly
moving out of the area. Medium range for Monday through Wednesday
looks mostly dry under the influence of a strong ridge. Temperatures
should warm up to near seasonal normals...perhaps a bit above normal
Monday and Tuesday as southerly flow increases ahead of the next
trof. Timing on when that trof will move out of the Great Plains
into the Mississippi Valley is currently low confidence with the
ECMWF bringing it in Wednesday but the slower GFS holding back until
later next week. Think the compromise forecast with PoPs increasing
to slight chance/low chance Wednesday and temperatures warming well
above normal into the upper 70s to around 80 looks good for now.
Carney
&&
.AVIATION... (For the 12z TAFs through 12z Friday Morning)
Issued at 652 AM CDT Thu Sep 29 2016
MVFR ceilings are expected to move into St. Louis terminals and
KUIN from the east between 13-15Z. Ceilings are expected to
increase to VFR during the afternoon before decreasing back to
MVFR and IFR late tonight and early Friday morning. There is a
slight chance of showers at the St. Louis area terminals during
the period, however confidence is too low at this time to include
them. Dry and VFR conditions are expected at KCOU.
SPECIFICS FOR KSTL: Ceilings around 2000ft AGL will move into the
terminal by 15Z. This ceiling is expected to raise back up to VFR
by midday before MVFR or IFR ceilings move into the terminal late
tonight and early Friday morning. There is a slight chance of
showers at the site during the period, how confidence is too low
at this time to include them.
Britt
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Omaha/Valley NE
605 AM CDT THU SEP 29 2016
.SHORT TERM...(today through Saturday)
Issued at 313 AM CDT THU SEP 29 2016
Latest water vapor imagery in addition to RAP 500 mb analysis
shows an upper ridge axis extending over the nation`s mid section.
This is sandwiched in between a trough to our west and a deep low
to our northeast. At the surface, a ridge axis extends from the
eastern Dakotas into eastern Nebrsaka. Some patchy fog cannot be
ruled out this morning with low dewpoint depressions, light winds
and clear skies. Otherwise, dry weather is expected to continue
for the forecast area through the weekend with temperatures close
to normal for this time of year as the upper low to our northeast
continues to spin south of the Great Lakes.
.LONG TERM...(Saturday night through Wednesday)
Issued at 313 AM CDT THU SEP 29 2016
By Saturday night, the previous mentioned upper low, having moved
only slightly, will begin to finally eject northeast into the
eastern Great Lakes region while the west coast trough continues
to deepen and shift east. Ahead of the west coast trough, strong
southerly flow will bring increasing moisture to the Central
Plains toward early next week. The next chance of
showers/thunderstorms looks to hold off until late Monday or early
Tuesday in warm air advection regime. Scattered chances will
continue into Wednesday before a cold front slides through the
area sometime mid week.
&&
.AVIATION...(12Z TAFS for KOFK...KLNK and KOMA.)
Issued at 605 AM CDT THU SEP 29 2016
Expect VFR conditions to prevail much or all of the period. There
will be some potential for some fog early this morning and again
Friday morning, mainly within a few hours of sunrise.
&&
.OAX Watches/Warnings/Advisories...
NE...None.
IA...None.
&&
$$
SHORT TERM...Kern
LONG TERM...Kern
AVIATION...Miller
Area Forecast Discussion
National Weather Service Phoenix AZ
845 AM MST THU SEP 29 2016
&&
.SYNOPSIS...
A low pressure system will continue to slowly move north through the
Desert southwest today resulting in variable cloudiness and a good
chance of showers and embedded thunderstorms. Dry and calmer weather
will return Friday through the weekend with seasonably warm
temperatures. Continued dry weather with a sharp cooling trend is
expected early next week as a strong area of low pressure passes by
to our north.
&&
.DISCUSSION...
Current radar imagery continues to show light shower activity moving
northward across south-central AZ this morning, with a few embedded
thunderstorms moving northward across SE Pinal County and Pima
County (TWC CWA). The latest HRRR high-res model run continues to
show this shower activity moving northward into the FGZ CWA by
midday today, with more activity developing later this afternoon
across extreme eastern Maricopa and South Gila Counties. The
activity this afternoon could be more robust, being enhanced by
diurnal heating and a well-defined shortwave that can be seen on IR
satellite imagery just now moving northward into extreme southern
AZ. In fact, SPC has parts of SE AZ in an MRGL risk area for svr
storms, with this area just clipping extreme eastern Pinal and
Southern Gila Counties, with forecast soundings showing 500-1000
J/KG of MLCAPE this afternoon, with the main threats being gusty
winds and small hail. Given current trends and latest forecasts,
inherited forecasts seem to cover the threat well, and no short-term
updates are planned at this time.
&&
.PREVIOUS DISCUSSION...
At 3 am this morning, IR imagery showed copious amounts of mid and
high level cloudiness streaming north/northeastward and into
Arizona, the remnants of a dissipating weak tropical weather system
still lingering along the central Baja coast. Another weak baggy
upper level low off central Baja was helping to push the moisture
north and into the state, and local radar showed scattered mostly
light showers developing in the moisture corridor, most numerous to
the south of Phoenix and across much of Pima as well as Pinal
Counties. For the rest of today, the weather pattern is rather
complex in terms of the details, but overall we can expect a series
of weak disturbances to move north and into Arizona, emanating from
the baggy low to our southwest, and these disturbances will act on
the moisture and lead to scattered showers and isolated embedded
thunderstorms. By this afternoon the best threat for convection will
focus on south-central Arizona, especially higher terrain areas to
the east of Phoenix where rain chances in excess of 50 percent are
located. For the most part rain totals will not be excessive but
brief heavy showers are certainly possible near any thunderstorm
that forms. Rain chances will extend into southeast California
today, but POPs will mostly be in the slight chance category.
Gradual drying from the southwest tonight is expected under the
influence of persistent southwest flow aloft, and dynamics will
gradually dissipate as much of the shortwave energy embedded in the
upper flow will lift to the north and northeast of central Phoenix.
Still, there will be enough lingering moisture and weak UVV fields
to keep scattered showers and possibly isolated thunderstorms going
mostly to the east of Phoenix and across the higher terrain. CAPE
values will be unimpressive tonight, mostly below 300 j/kg so any
storms that form should not be overly strong.
Expect continued drying from the west Friday, as southwest flow
aloft strengthens as a deep Pacific upper trof continues to develop
along the nrn California and Pacific Northwest coast. Low level
moisture across south central AZ will be somewhat hard to scour out,
despite the increasing west/southwest flow aloft so there will be a
lingering slight chance of showers or storms from Phoenix east on
Friday and this is supported by the NAEFS POPs. High temperatures
will stay near seasonal normals Friday in the central deserts, and
will rise into the upper 90s out west where drier air and ample
sunshine are present.
Over the weekend, no significant changes to the weather pattern are
expected; the deep trof to our west will slowly push toward the
coast and eventually move inland over the west coast by Sunday
afternoon. Southwest flow aloft will persist area-wide keeping sunny
days and clear nights in play from Phoenix west, and high
temperatures will edge downward slightly but remain near seasonal
normals. Low level moisture will still linger in far eastern
Arizona, and the ECMWF suggests that an isolated shower/storm could
be possible east of Globe over the higher terrain, but we will keep
POPs in the single digits east of Phoenix, more along the lines of
the NAEFS numbers.
Monday into Tuesday...both the GFS and the ECMWF agree that the deep
upper trof will push east through the western CONUS with the main
center moving well to our north and across Utah. Strong westerly
flow aloft will affect southern Arizona, keeping conditions dry and
breezy and as heights fall with the trof passage, high temperatures
will fall substantially. Highs over the deserts will drop into the
80s both days with the coolest day in Phoenix expected to be Tuesday
with a high of just 84 degrees for Phoenix Sky Harbor. Normal high
in Phoenix on Tuesday is 93 degrees.
Dry subsident northwest flow aloft is expected Wednesday for sunny
days and clear nights and continued below seasonal normal high
temperatures as the deserts remain in the 80s.
&&
.AVIATION...
South-Central Arizona Including KPHX, KIWA, and KSDL:
A broad area of scattered light showers oriented SW-NE will affect
the area through 16Z before clouds begin to decrease from the
southeast. A stray thunderstorm is possible, but likelihood too low
to reflect in the TAFs. Expect ceilings to remain above FL070 and
vsbys to remain solidly in VFR territory. The showers will disrupt
the light easterly winds but anticipate speeds to remain below 12kts.
Anticipate a northerly component becoming favored by 17Z then
trending toward westerly in the afternoon. Redevelopment of showers
and thunderstorms can be expected over the eastern third of AZ
(mainly east of a TUS- PAN line) and thus there is some potential for
outflow from distant storms. Couldn`t rule out a stray thunderstorm
moving through the metro after 23Z but likelihood too low to reflect
in TAFs.
Southeast California/Southwest Arizona including KIPL and KBLH:
Isolated to scattered showers will mainly stay east of a IPL-IFP
line today before dissipating by 00Z. Expect ceilings to remain AOA
FL090. Winds will remain light and favor south and southeasterly
directions today.
&&
.FIRE WEATHER...
Saturday through Wednesday...
A dry regime will be in place Saturday through Wednesday. A low
pressure system passing mainly through the Great Basin will lead to
breezy to locally windy conditions Sunday through Tuesday. Humidities
will decline with minimum values on the lower deserts in the 10-15%
range by Monday with little change thereafter. Overnight recovery
declines as well but remains fair. Temperatures drop well below
normal by Monday with highs remaining in the 80s on the lower deserts
through Wednesday.
&&
.SPOTTER INFORMATION STATEMENT...
Skywarn radio Net activation will not be needed.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook...Twitter...and at weather.gov/phoenix
DISCUSSION...Percha/CB
AVIATION...AJ
FIRE WEATHER...AJ
AREA FORECAST DISCUSSION
National Weather Service Des Moines IA
337 PM CDT Thu Sep 29 2016
.SHORT TERM.../This evening through Friday/
Issued at 334 PM CDT Thu Sep 29 2016
Little of concern tonight outside of possible fog redevelopment. The
Ohio Valley upper low should remain nearly stationary with clear
skies across Iowa. The broad low level cyclonic flow continues to
drawn in some lower humidities, especially east, however the latest
RAP shows somewhat higher 0-500m RH north and west. This is also
where early morning stratus and fog lingered so have introduced some
patchy fog wording there early in the morning with clear skies and
light wind.
.LONG TERM.../Friday night through Thursday/
Issued at 334 PM CDT Thu Sep 29 2016
The more likely window for sensible weather through this period will
be toward the middle of next week, although the current Ohio Valley
upper low may just brush Iowa with light precip over the weekend.
The models are in good agreement drifting the system back to
southern Lake Michigan by late Saturday. The forcing will be neutral
or subsident but increasing moisture 3km and below may be sufficient
to squeeze out some light showers east. The system should finally
depart to end the weekend as the western CONUS trough advances.
This will increase temps and moisture somewhat as return flow
begins and ridging enters Iowa. The GFS and ECMWF are now fairly
consistent and suggest deep forcing increasing west to east
Tuesday Night into Wednesday. Timing is still somewhat suspect
however with the ECMWF frontal passage much faster, so while the
best window appears to be around Wednesday have lingered some low
PoPs east into Thursday. Instability looks weak regardless of the
solution, but both deep and shallow shear are quite high. This
suggests somewhat of a weak, subtle fall QLCS tornado threat if
diurnal timing is favorable due to the high shear values 3km and
below.
&&
.AVIATION.../For the 18Z TAFS through 18Z Friday afternoon/
Issued at 1240 PM CDT Thu Sep 29 2016
Once KFOD stratus clears shortly, there will be a high confidence
in VFR conditions at all sites through the evening hours. However
confidence decreases somewhat into early Friday morning due to fog
and stratus re-development uncertainties. For now have included
MVFR fog at KFOD until confidence increases, but lower and more
widespread conditions are possible.
&&
.DMX WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...Small
LONG TERM...Small
AVIATION...Small
Area Forecast Discussion
National Weather Service Quad Cities IA IL
302 PM CDT THU SEP 29 2016
.SYNOPSIS...
Issued at 300 PM CDT Thu Sep 29 2016
18Z surface analysis has high pressure from the upper Great Lakes
into the southern Plains while a cut off upper low was over the
lower Ohio Valley. Dew points were in the 40s and 50s from the
Plains into the Ohio Valley.
&&
.SHORT TERM...(This Evening through Friday)
ISSUED AT 300 PM CDT Thu Sep 29 2016
Through sunset, mainly clear skies will be seen across much of the
area with clouds and isolated showers/sprinkles across the far
eastern parts of the area. After sunset and through much of the
evening, isolated sprinkles/showers will gradually decay across the
far east.
The upper low over Kentucky will remain there through Friday. Trends
with the RAP and other models indicate another surge of low clouds
will spread west again after midnight with widespread cloud cover
over the eastern two thirds of the area around sunrise Friday.
On Friday, several additional upper level disturbances will rotate
through the area. These disturbances will slowly spread isolated to
scattered rain showers west across the area during the day.
The initial dryness of the air indicates some chilly temperatures
are possible tonight, especially those areas that remain clear.
On Friday, cloud cover/precipitation will make temperatures very
interesting. High temperatures should eventually get into the 60s at
some point during the afternoon.
.LONG TERM...(Friday Night through Thursday)
ISSUED AT 300 PM CDT Thu Sep 29 2016
Forecast focus on chance of showers early in the extended then
chance of thunderstorms about the middle of next week.
Friday night through Saturday: Vertically stacked upper low in KY
will track slowly northward into northern Indiana. The cyclonic
flow/cold pocket around the low will bring a mostly cloudy sky to
the dvn cwa, along with scattered showers. The higher pops (40-50
pct) will be kept roughly along and east of the MS River, closer to
the low. In our far western counties pops will be in the 20-30 pct
range. Highs on Saturday should range from 65 to 70 due to the
extensive thick cloud cover.
Saturday night through Tuesday night: A pleasant stretch of weather
expected, dry with a warming trend. The upper low will be shifting
into the eastern Great Lakes during the weekend, while ridging aloft
builds into the cwa. Highs will be in the upper 60s to lower 70s on
Sunday, warming well into the 70s by Tuesday. Lows will be mainly in
the 50s.
Wednesday through Thursday: Low confidence due to potential Tropical
Storm or Hurricane Matthew moving up the East Coast (GFS) vs the
system still near the Bahamas (ECMWF). Both models sweep a negative-
tilt trough/strong cold front into the Midwest, accompanied by
showers and thunderstorms. So, there are two scenarios 1) the
tropical system slows the approaching trough or 2) the trough sweeps
to the east and merges with the tropical system. As of now, the ECM
with the slower movement to "Matthew" sweeps the cold front across
the cwa on Wednesday. On the other hand, with the tropical system
moving up the East Coast the GFS is about 24 hours later with the
arrival of the front. The consensus model has chance pops to cover
the two scenarios described above.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
ISSUED AT 1220 PM CDT Thu Sep 29 2016
VFR conditions will be seen through 06z/30. Some VFR cigs are
possible at KBRL/KMLI. After 06z/30 MVFR cigs will again slowly
build west to the Mississippi river and then into eastern Iowa by
sunrise Friday. After sunrise Friday, MVFR and possibly some IFR
conditions will be seen across eastern Iowa and northern Illinois
with rain showers.
&&
.HYDROLOGY...
Issued at 1224 PM CDT Thu Sep 29 2016
Mississippi River:
Latest adjustments that were made was to slightly lower crest
forecasts at most points but minor to major flooding continues to be
on track. Forecast point DLDI4 Dubuque is expected to crest right at
flood stage with major flooding still expected at New Boston,
Keithsburg,Gladstone and Burlington. Majority of the crests are
projected to occur during the Saturday through Monday time frame.
No significant rain is expected through the middle of next week.
Cedar River...
Vinton: Forecast to fall below flood stage by Friday morning.
Cedar Rapids: Forecast to fall below major flood stage by late
tonight.
Conesville: Cresting near 18.1 feet through this evening
before beginning to slowly fall.
Wapsipinicon River...
Anamosa Shaw Rd: Forecast to fall below moderate flood stage by
the late evening.
De Witt 4S: Now into major flood stage. Thinking current crest
forecast at 13.4 feet is on the upper end of possible outcomes.
Reasonably high probability the final crest is a bit lower.
Iowa River...
Marengo: Moderate flood stage is forecast by Friday afternoon or
evening.
Columbus Junction: Major flooding is occurring. Rate of rise has
slowed but is forecast to increase tonight.
Oakville and Wapello: Moderate confidence is associated with the
crest forecasts. Current thinking is crest forecasts are toward the
upper range of what is possible; observed crests may come in lower.
Please follow forecast information closely throughout this event.
&&
.DVN Watches/Warnings/Advisories...
IA...NONE.
IL...NONE.
MO...NONE.
&&
$$
SYNOPSIS...08
SHORT TERM...08
LONG TERM...Haase
AVIATION...08
HYDROLOGY...Haase/Uttech
Area Forecast Discussion
National Weather Service Wilmington NC
612 PM EDT Thu Sep 29 2016
.SYNOPSIS...
A stationary front will waver along the coast through this
weekend. Periods of showers with an isolated thunderstorm are
possible along this front. Weak high pressure will build in
early next week. Hurricane Matthew may bring increasing waves
by the middle of next week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 345 PM Thursday...WV imagery paints the picture this aftn with
a massive bowling ball of an upper low spinning across IN/KY, and
our sensible weather is almost exclusively developed in response to
this feature. The southern side of this low features very dry air
moving across the Gulf Coast states and pushing into SC/NC, while on
the eastern side moisture remains deep, and lift is being aided by
diffluence at 500mb and above, creating the tremendous rain seen
across portions of eastern NC today. The dividing line between these
two features is a nearly stationary cold front, recognized more by a
dewpoint gradient than any significant temperature advection, and
while this front will try to push slowly east, it is aligned nearly
parallel to the mid-level flow and will struggle to make much
longitudinal gain through tonight.
The combination of this cold front, significant diffluence aloft,
and many mesoscale outflow boundaries has allowed convection to
become deep and heavy, and a flash flood watch remains in place for
all of SE NC until 10pm. A line of storms has developed along a 925-
850mb confluence boundary which is somewhat being aided by a weak
sea breeze as well. Convergence along this line combined with
diffluence at 300mb is driving updrafts upward, but with only
marginal MLCape in an environment of high freezing levels and high
PWATs, warm rain processes are likely dominating any Bergeron
processes, and hence rain rates are very impressive - 2 to 3 inches
per hour at times. While the mean flow is from the SW, driving
storms to the NE, they continue to redevelop to the SW, so more
flash flooding is possible through this evening, especially in
places that haven`t been worked over already. High res ARW and RAP
continue to model this pretty well, and this suggests convection
will wane with loss of heating this evening. Another round of
showers/storms may approach the coast overnight as another vort lobe
rotates northward near the area, but most of this precip is forecast
to remain just offshore.
Another thing to note is that, while SPC has removed the MRGL risk
locally, a hybrid outflow/warm front exists across NE SC. As cells
move across this boundary they are ingesting enhanced helicity and
latest SPC mesoanalysis has 100-150 m2/s2 of 0-1 km SRH. This is not
abnormally strong, but have noticed several weakly rotating cells,
and this will likely continue for several more hours. Local
hodographs are not very supportive for any tornadoes due to
primarily unidirectional flow, but local backing along this boundary
is enough to keep cells rotating, with just a very minimal chance
for a tornado this aftn.
After convection wanes tonight, southerly winds will persist, mainly
near the coast, with some light W/SW winds developing far western
zones near/behind the cold front. This creates a challenging
temperature forecast with a significant gradient from west to east,
but expect lows near the coast to remain warm, low 70s, with some
mid 60s possible well west of i-95.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
As of 345 PM Thursday...Little change in the synoptic setup into the
weekend as bowling ball of the upper low spins slowly across IN/KY
before lifting into OH late in the period. At the surface, a very
slow moving cold front will push eastward, likely finally crossing
offshore Friday night before stalling once again. With diffluence
remaining east of the upper low, and low level confluence likely
persisting along and east of the boundary, more convection with
periods of heavy rain is forecast Friday. The best chance for
rainfall will again be the eastern third of the CWA where mid-level
RH remains elevated despite a very dry punch within the dry slot
working into the Pee Dee. This creates 2 distinct air-masses across
just the local CWA, with PWATS forecast to drop below 1 inch well
inland, while remaining at 1.5-1.75 near the coast, and inland
counties may finally have a dry day Friday. By Saturday, most of the
CWA is forecast to get into the drier air, but once again the
immediate coast may still see no relief from this humid airmass with
more showers/tstms possible along the coast.
Highs both Friday and Saturday are forecast to be slightly above
climo, low 80s, but will be heavily impacted by clouds and rainfall.
Mins inland will drop into the upper 50s/low 60s both nights within
that drier air mass, but will remain near 70 at the coast.
&&
.LONG TERM /SUNDAY THROUGH THURSDAY/...
As of 3 PM Thursday...Incredibly the relatively sharp west to east
precipitable water gradient remains in place across NE SC/SE NC much
of the extended period before the potential of tropical moisture
late next week. In essence this brings a sensible weather forecast
of chances for showers near the coast and very little along the far
interior zones. This in part due to the dry mid-level air wrapped
around the large upper low to the west, and the remnant presence of
dry air aloft across the area even as the low pulls away from the
region on Sunday. Even so a chance of showers will prevail along
the eastern 1/3 of the forecast zones days 4-7 with isolated TSTMS
favored nocturnally over the coastal waters, or a sea breeze pop up
in the middle afternoon. Temperatures to run near to a bit above
normal, especially for the minimums this period. Tempering of
maximum temperatures days 6 and 7 is attributed to increasing NE flow
across the area, but about normal max temp readings for early OCT.
&&
.AVIATION /00Z THURSDAY THROUGH TUESDAY/...
As of 00Z...Upper low still nearly stationary, with a weak surface
front over our CWA. Look for dying convection over the next several
hours. Showers could briefly affect the coastal terminals, with VCSH
sufficing for now. Overnight, some light fog is possible, briefly
IFR at LBT. A coastal shower cannot be ruled out along the coast
toward morning. Friday, more of the same with convection becoming
scattered, most numerous around or just after max heating.
EXTENDED OUTLOOK...Primarily VFR. Isolated to scattered afternoon
showers through much the period, although limited in strength and
coverage due to dry air aloft.
&&
.MARINE...
NEAR TERM /THROUGH TONIGHT/...
As of 345 PM Thursday...Surface cold front will remain well inland
through tonight, and winds over the waters of 10-15 kts will persist
from the south through the near term. With these winds creating a
2ft/4-5 sec southerly wave, and a low-amplitude 10-11 sec SE swell
also existing, seas will remain 3-4 ft through tonight. Showers and
thunderstorms may develop late in the period as well, most likely
affecting the outer portions of the NC waters.
SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
As of 345 PM Thursday...A cold front will be west of the waters
Friday before wavering across or potentially still just inland on
Saturday. This creates predominantly S/SW winds of 10-15 kts on
Friday, backing to the SE around 10 kts on Saturday, again dependent
on where the front stalls. A period of variable winds is possible
late Friday into Saturday as the front drifts into the vicinity, but
speeds will be light during that time. Seas will hover around 3 ft
both Friday and Saturday with a low amplitude 9-10 sec SE swell and
2-3 ft 5 sec southerly wind wave comprising the spectrum.
LONG TERM/SUNDAY THROUGH TUESDAY/...
As of 3 PM Thursday...This period will be marked by 3-5 foot seas
and highest seas offshore, but elevated wave heights may
gradually arrive after Tuesday due to increasing swell from
Hurricane Matthew. No advisories expected through Tuesday.
Isolated showers and TSTMS can be expected this period and radar
updates are encouraged.
&&
.ILM WATCHES/WARNINGS/ADVISORIES...
SC...None.
NC...Flash Flood Watch until 10 PM EDT this evening for NCZ087-096-
099-105>110.
MARINE...None.
&&
$$
SYNOPSIS...8
NEAR TERM...JDW
SHORT TERM...JDW
LONG TERM...Colby
AVIATION...43
Area Forecast Discussion
National Weather Service Northern Indiana
242 PM EDT Thu Sep 29 2016
.SYNOPSIS...
Issued at 237 PM EDT Thu Sep 29 2016
Low pressure will slowly drift back north into Michigan and
eventually Ontario over the next couple of days. Increasing
chances for showers and a few thunderstorms will occur starting
this evening and persisting into Saturday. Highs will remain near
or slightly above normal in the middle to upper 60s.
&&
.SHORT TERM...(This Evening through Friday)
Issued at 237 PM EDT Thu Sep 29 2016
Thus far this afternoon convection has been to the north and west
of the area with other activity rotating towards the northwest
from eastern/central Ohio associated with the next wave. This
activity will pose the main concern mid evening into early Friday
with potential for pockets of moderate to heavy rain possible.
Before then expecting more of a hit and miss convective regime
with some potential expansion in the 21 to 00z window before
diminishing. Used HRRR experimental as it keyed in well yesterday
on convective development and has been overall decent today. May
need a further increase/expansion in pops given upstream trends
but for now have held no more than likely pops.
Coverage will increase even further Friday as strongest wave rotates
around the upper low and it moves back north across the area. Severe
weather not anticipated but could see some small hail with the
stronger cells.
&&
.LONG TERM...(Friday Night through Thursday)
Issued at 237 PM EDT Thu Sep 29 2016
Deep upper low will final begin to make a trek back towards the
north into Ontario Sunday and eventually New England by Tuesday.
Several pieces of energy will still be rotating around the low to
bring periodic chances for showers (storms?) into Saturday with
trends finally heading towards drier conditions Sunday and
especially Monday through Wednesday. While convection will mainly be
diurnally driven Sat afternoon/eve chance will exist just about
anytime so will maintain chance or slight chance pops outside
time frames with greatest potential.
A period of above normal temperatures will arrive with highs well
into the 70s through Wednesday as yet another trough digs into the
Plains with models differing on exact handling and timing as what
will likely be Hurricane Matthew may be raising havoc with the upper
level flow mid to late week. Slight chance to chance pops mainly
west Weds Ngt into Thursday as main dynamics remain to the west.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday Afternoon)
Issued at 1255 PM EDT Thu Sep 29 2016
An upper low should remain over the area through the TAF period.
Some sun has allowed destabilization with showers becoming more
numerous near the Michigan/Indiana line. Have mentioned these
showers in a TEMPO group at South Bend. Otherwise, conditions
should become IFR tonight.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...NONE.
MI...NONE.
OH...NONE.
LM...Small Craft Advisory until 6 PM EDT Friday for LMZ043-046.
&&
$$
SYNOPSIS...Fisher
SHORT TERM...Fisher
LONG TERM...Fisher
AVIATION...Skipper
Visit us at www.weather.gov/iwx
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AREA FORECAST DISCUSSION
National Weather Service Jackson KY
656 PM EDT Thu Sep 29 2016
.UPDATE...
Issued at 656 PM EDT THU SEP 29 2016
The more scattered coverage of showers and isolated storms
resides across the far east this evening and another area of just
showers across the Lake Cumberland region this hour. Between these
two areas is a relative lull and even clearing skies. This is all
being aided by a upper level low that is generally centered
across south central KY this evening. Overall think the forecast
package in the near term looks on track and will have to keep a
eye on radar trends through the night. Did opt to remove thunder
after 01Z, but kept in through then given the isolated strikes we
have seen in the far east toward Letcher and Martin Counties.
Otherwise only minor updates to latest obs and trends were
needed.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 440 PM EDT THU SEP 29 2016
19z sfc (and aloft) analysis shows a stacked low spinning over
Central Kentucky. This is clearly seen in the movement of the
scattered convection throughout the region as well as the clouds
on visible satellite. The convection was and is best developed in
far eastern Kentucky - particularly in RLX`s area where some
large hail has fallen. In fact, the storms to the east have been
well organized with decent low level rotation and evidence of
splitting cells. Will have to keep an eye on the far east and
northeast parts of the area into the evening. Temperatures did not
recover much from overnight lows today thanks to the clouds and
pcpn. At 3 pm readings varied from the mid 50s in the east with
the steadier rains to the lower 60s over the somewhat drier
Cumberland Valley. Winds have been light and variable through the
day with a tendency for them to come out of the north and
northwest while dewpoints have fallen into the low to mid 50s most
places.
The models are in good agreement aloft through the short term
portion of the forecast. They all depict a bowling ball of low
heights centered over Central Kentucky through midday Friday. This
feature will then meander back north to northwest into Saturday
morning. Plenty of energy accompanies the heart of the low and
will continue to spin over Kentucky. Late in the period there are
some differences starting to show up among the models with the
GFS the slowest to ease away from JKL and the NAM slightly
quicker. Given the similarities in guidance will favor a blended
solution with emphasis on the HRRR in the near term.
Sensible weather will feature a chilly and damp evening for most
with a potential for a couple of thunderstorms in the far east.
Some small hail cannot be ruled out from any stronger storm that
develop given the low freezing level. Fog will be possible
overnight and not just confined to the valleys as stratus is
expected to build down on the ridges, as well. Look for mainly a
few scattered showers around the fringes of the CWA later tonight
through Friday as the core of the upper low slips off to the west
and we start to dry out. Clouds will remain, though, limiting the
diurnal rise and fall through the rest of the forecast, but highs
should be a category or two higher than today.
Used the CONSShort and ShortBlend as a starting point for most
grids into Friday morning with the SuperBlend used thereafter.
Made only minor changes to the T grids based on our terrain. As
for PoPs - ended up similar to a MOS blend through Saturday
morning.
.LONG TERM...(Saturday through Thursday)
Issued at 325 PM EDT THU SEP 29 2016
The extended period should feature isolated rain showers to begin
the period Saturday and Sunday, as a slow moving area of low
pressure slowly rotates through the region. They system will have
only meager lift an moisture associated with it, so any showers that
form with it should be isolated to scattered at best, mainly for the
western and northern portions of the forecast area. Once the upper
low rotates out of the Ohio Valley and out of our area Sunday
evening, the remainder of the extended should be dry and pleasant. A
ridge of high pressure is forecast to settle over the region through
out the upcoming work week, which would bring mostly clear to partly
cloud skies, dry conditions, and light winds to eastern Kentucky.
Daily highs are expected to top out in the 70s for most locations. A
few spots along and south of the Hal Rogers Parkway and Highway
corridor may reach or slightly exceed 80 degrees Tuesday and
Wednesday. Nightly lows should bottom out in the 50s.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
ISSUED AT 225 PM EDT THU SEP 29 2016
Cigs should continue to improve throughout the afternoon with vis
restrictions only due to showers or a stray storm. Later tonight,
dependent on how much low level moisture sticks around and how
many locations see rain today, fog will be possible. In addition
to the fog, cigs will also fall through the night with IFR and
MVFR to be common. Look for conditions to improve to VFR at most
sites Friday morning. Winds will remain around 5 knots or less
throughout the period.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...DJ
SHORT TERM...GREIF
LONG TERM...AR
AVIATION...GREIF
Area Forecast Discussion
National Weather Service Twin Cities/Chanhassen MN
342 PM CDT THU SEP 29 2016
.SHORT TERM...(This evening through Friday)
Issued at 315 PM CDT Thu Sep 29 2016
The main feature of interest continues to be the deep vertically
stacked low that has moved over Kentucky this afternoon as evident
by the tight circulation on satellite. To the west of this system
in our area, an upper ridge has been slowly pushing in from the
west, bringing drier air and mostly clear skies to the Upper
Midwest. The exception today was the cool and moist air off Lake
Superior that spread stratus across much of Minnesota.
The cloud cover across central Minnesota is scattering out quickly
this afternoon and that trend will continue, with skies expected to
be clear tonight. The concern late tonight is for fog across the
area with the ridge axis in place. Very light winds and clear
skies, along with hydrolapses increasing with height indicate the
potential for some fog across the area, some locally dense.
Tomorrow will be mostly clear, and a few degrees warmer than the
past couple, but the low in Kentucky today will be drifting back
north-northwest and spread clouds late in the day into western WI
and eastern MN.
.LONG TERM...(Friday night through Thursday)
Issued at 315 PM CDT Thu Sep 29 2016
Movement of the upper low over the Ohio River Valley/Great Lakes
and the western CONUS trough into midweek are the main concerns in
the longer term.
The longer term deterministic models continue to show moisture
advecting westward over the cwa Friday night and lingering over
most of the area into Saturday night. We expect another mostly
cloudy trend as this moves through. There may be some light
showers affecting a small portion of west central Wisconsin late
Friday night into Saturday as the lower level moisture
arrives...but the remainder of the area should be dry. With more
clouds around...overnight lows shouldnt drop off too much with
upper 40s/low 50s common through Saturday night. If we see more
clearing...temperatures a be a little cooler than forecast...but
that is not expected at this time.
With the upper low exiting the area later Sunday into Monday...we
expect a little more sunshine to develop along with warmer
temperatures. The western CONUS trough will move slowly east and
begin to draw moisture northward back into area by late Monday
night to far western CWA and spread east into west central
Wisconsin mainly Tuesday night through Thursday. We continued the
slower trend of drawing in higher pops during this period. The GFS
ultimately has a problem with phasing the tropical system lifting
north from the Caribbean/Matthew and begins to split energy with
the amplified trough over the upper Mississippi River valley. We
like the evolution/movement of the 12z ECMWF concerning the
trough...and followed this more at least initially. We did retain
the chance thunder with the system as well. Cooler temperatures
will accompany and follow the system through the end of next week.
&&
.AVIATION...(For the 18Z TAFS through 18Z Friday afternoon)
Issued at 1238 PM CDT Thu Sep 29 2016
The upper low that was over the southern Great Lakes yesterday has
moved south into southern IN/northern KY, with a surface high in
Ontario. Stronger than expected northeast flow in between these
areas led to cool and moisture advection off Lake Superior this
morning and low ceilings moved in to parts of West Central
Wisconsin and eastern Minnesota. Farther south, LIFR ceilings and
fog have since dissipated. The southern end of the the stratus
from the Lake Superior is expected to slowly erode from the south
this afternoon and evening. STC and AXN will deal with the clouds
the longest, but bases should remain at VFR levels. Tonight, fog
will be possible across the area and included some mention of fog
at each TAF site. The HRRR indicates moisture off Superior
affecting north central MN, so we think AXN would be most
susceptible to fog overnight. ENE winds today will become light
overnight, and increase to near 7 knots from the NE tomorrow.
Clouds from the Upper Low will approach from the southeast
tomorrow during the day.
KMSP...Starting off with a tempo BKN025 for an hour as ceilings
should lift and continue a scattering trend this afternoon. Expect
clear skies tonight, but could see some fog early tomorrow
morning. ENE winds gusting to 16 knots this afternoon are expected
to become light tonight, and around 5-7 knots tomorrow. Could see
stratus filling in from the east tomorrow late afternoon as that
upper low lifts north.
/OUTLOOK FOR KMSP/
Sat...VFR. Wind ENE at 5 kts.
Sun...VFR. MVFR possible. Wind NE at 5 kts.
Mon...VFR. Wind SE at 5-10 kts
&&
.MPX Watches/Warnings/Advisories...
WI...None.
MN...None.
&&
$$
SHORT TERM...SPD
LONG TERM...DWE
AVIATION...SPD/AMK
Area Forecast Discussion
National Weather Service New York NY
611 PM EDT Thu Sep 29 2016
.SYNOPSIS...
High pressure over southern Quebec will maintain a moist northeast flow
off the Atlantic Ocean into the weekend as low pressure spins
over the Ohio Valley. The unsettled weather may continue into early
next week before high pressure begins to exert its influence from
the north for mid week.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
The problem in the near term is the rain pushing north out of
south and central Jersey. Believe the 12Z ECMWF has a good handle
on this. But confidence is low since latest RAP and HRRR keep us
basically dry overnight. The rain is in response to the strong
over-running of the coastal front to the south.
Have followed the deterministic ECMWF for POPs and QPF - which
again may be way too high, but current RADAR trends are hard to
ignore.
Also, the cloud cover forecast over CT is a problem. Would suspect that
this fills in quickly this evening, but is may be later rather
than sooner.
NOTE: We have ended our Surf Zone Forecasts for the Long Island
Beaches. With seas up to 6 ft in the surf zone and strong long
shore currents - even experienced surfers should exercise extreme
caution.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Following the ECMWF 12Z deterministic run for tomorrow.
The uncertainty remains on the intensity of the rain. With the 15Z
SREF support rain through the period, the categorical POPs should
work out. Not a very nice day for most!
Winds will gust as high as 40 mph along the coast.
&&
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Stagnant and unsettled weather pattern continues into this weekend
with stacked cutoff low pressure sitting over the Ohio valley...as
western Atlantic ridging holds firm. Models indicating that the
upper ridge gradually weakens and shifts south enough early next
week to allow the upper low to finally start moving northeast early
next week.
At the surface...stacked low pressure sits over the Ohio
Valley...with its warm front remaining stationary running northeast
from the Mid Atlantic and southeast of Long Island through the
weekend. A series of weak waves running along this front will result
in periods of rain this weekend. Then as the stacked low finally
begins to lift northeast early next week...expect the the main
moisture/lift axis to weaken and lift NE of the region. Lingering
scattered shower activity possibly continues through early next week
with cold pool instability interacting with the maritime airmass.
Thereafter...potential for deep layered ridging developing for mid
week as the region lies under ridging of an omega blocked pattern.
The dry ridged pattern may continue into late week...but will have
to monitor the evolution of Hurricane Matthew. Refer to the National
Hurricane center forecasts for the latest information.
Temps likely several degrees below seasonable Sat and possibly Sun
with cold air damming...clouds and rainfall. Near seasonable temps
likely for early next week.
&&
.AVIATION /22Z THURSDAY THROUGH TUESDAY/...
Terminal area will be in between high pressure to the northeast and
low pressure to the southwest into Friday afternoon.
MVFR ceilings return overnight to all but KSWF and KGON where it
should develop Friday morning. Light rain looks to start towards
sunrise Friday, with moderate rain developing by mid-late Friday.
The exception is at KGON, where light rain should hold off until
around midday on Friday.
NE-E winds through the TAF period, gusting to 25-35kt at
city/coastal terminals and 15-25kt at inland terminals. Gusts could
be intermittent at times into this evening.
NY Metro Enhanced Aviation Weather Support...
Detailed information, including hourly TAF wind component forecasts,
can be found at: http:/www.weather.gov/zny/n90
KJFK TAF Comments: Peak gusts could be 5kt or so higher than
those in TAFs.
KLGA TAF Comments: Variable ceilings between VFR and MVFR possible
into this evening. Peak gusts could be 5kt or so higher than those in
TAFs.
KEWR TAF Comments: A chance of VFR this evening. Peak gusts could
be 5kt or so higher than those in TAFs.
KTEB TAF Comments: Variable ceilings between VFR and MVFR possible
into this evening. Peak gusts could be 5kt or so higher than those
in TAFs.
KHPN TAF Comments: Variable ceilings between VFR and MVFR possible
into this evening. Peak gusts could be 5kt or so higher than those
in TAFs.
KISP TAF Comments: Peak gusts could be 5kt or so higher than
those in TAFs.
.Outlook for 18Z Friday through Monday...
.Friday Afternoon-Saturday...IFR/MVFR in rain. NE winds g25-35 kt
Friday afternoon/evening.
.Saturday Night-Sunday Night...MVFR or lower possible with showers.
.Monday-Tuesday...VFR with isolated to scattered showers possible.
&&
.MARINE...
Winds increase slightly overnight into Friday Morning...thus have
issued a gale warning for all waters except NY Harbor.
SCA conditions expected Friday night into Saturday for the
Ocean...possibly all waters...but should begin to relent Sat
night into early Sunday as easterly flow weakens. Ocean seas
should follow suit as well.
Sub SCA conditions likely for early next week under weak pressure
gradient.
&&
.HYDROLOGY...
There is a high degree of uncertainty on the amount of rainfall
through Friday. Moderate rainfall overnight into Friday morning
for western sections and the NY Metro is possible with up to an
inch of QPF possible.
Overall, totals should range in the 1-2" range through Saturday
night, though this may be on the high end depending on how things
evolve overnight into Friday Morning.
Regardless, the prolonged nature of the rain event should
preclude any hydrologic issues.
No significant rainfall for early to mid next week.
&&
.TIDES/COASTAL FLOODING...
A persistent moderate northeast flow through Friday will keep persistent
elevated water levels.
Water levels across the Atlantic Ocean facing south shore bays in
Nassau will reach minor tidal flooding benchmarks again tonight -
a few inches higher than this morning.
Latest data does not support expansion of the minor flooding on
Friday - with just the bays of southern Nassau reaching minor
benchmarks.
An advisory has been issued for this evening`s and tomorrow`s high
tide. Another advisory will likely be needed for Friday evening`s
high tide.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...Coastal Flood Advisory until 10 PM EDT this evening for NYZ179.
Coastal Flood Advisory from 6 AM to 9 AM EDT Friday for NYZ179.
NJ...None.
MARINE...Small Craft Advisory until 6 PM EDT Friday for ANZ338.
Gale Warning until 6 PM EDT Friday for ANZ330-335-340-345-350-
353-355.
&&
$$
SYNOPSIS...Tongue
NEAR TERM...Tongue
SHORT TERM...Tongue
LONG TERM...NV
AVIATION...IRD
MARINE...Tongue/NV
HYDROLOGY...Tongue/NV
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Phoenix AZ
145 PM MST THU SEP 29 2016
&&
.SYNOPSIS...
Low pressure and tropical moisture moving northward over the desert
southwest will continue to produce showers and thunderstorms over
the region through tonight. Dry and calmer weather will then return
Friday through the weekend with seasonably warm temperatures.
Continued dry weather with a sharp cooling trend is expected early
next week as a strong area of low pressure passes by to our north.
&&
.DISCUSSION...
Tonight...
Another in a series of shortwaves embedded in broad southerly flow
over the region managed to trigger a band of showers and
thunderstorms this morning over south-central and SW AZ as it moved
northward across the region. At this hour, we are in a break between
systems, with most of the significant convective active now moving
off well to our north, into parts of NE AZ. It appears one more
round of convective activity will be affecting our cwa later this
afternoon/evening as a combination of daytime heating, ample low-
level moisture (sfc dewpoints well up into the 60s), and increasing
mid-level shear (bulk shear values in the 30-35 kt range) ahead of
the next shortwave is already beginning to generate new showers and
thunderstorms across SE AZ. Given the high bulk shear values and
observed MLCAPES across SE and Eastern AZ, as well as mid-level
lapse rates in the 6.0-7.0 C/KM range, SPC has placed parts of our
cwa in a marginal risk area for severe thunderstorm development,
mainly for locally severe winds and small hail. Both SPC and the
last several HRRR high-res model runs favors Southern Gila County
and extreme eastern Pinal county for any severe thunderstorm
development, with much lesser chances across the remainder of south-
central AZ. Along with the shower/thunderstorm chances, there is
once again the risk for blowing dust across the lower elevations of
Maricopa/Pinal Counties as outflows from distant thunderstorms to
the south will likely move into the region.
Gradual drying from the southwest later tonight is expected under
the influence of persistent southwest flow aloft, and dynamics will
gradually dissipate as much of the shortwave energy embedded in the
upper flow will lift to the north and northeast of central Phoenix.
Still, there will be enough lingering moisture and weak UVV fields
to keep scattered showers and possibly isolated thunderstorms going
mostly to the east of Phoenix and across the higher terrain. CAPE
values will be unimpressive later tonight, falling mainly below 300
j/kg so any storms that form should not be overly strong.
Friday through Wednesday...
Expect continued drying from the west Friday, as southwest flow
aloft strengthens as a deep Pacific upper trof continues to develop
along the nrn California and Pacific Northwest coast. Low level
moisture across south central AZ will be somewhat hard to scour out,
despite the increasing west/southwest flow aloft so there will be a
lingering slight chance of showers or storms from Phoenix east on
Friday and this is supported by the NAEFS POPs. High temperatures
will stay near seasonal normals Friday in the central deserts, and
will rise into the upper 90s out west where drier air and ample
sunshine are present.
Over the weekend, no significant changes to the weather pattern are
expected; the deep trof to our west will slowly push toward the
coast and eventually move inland over the west coast by Sunday
afternoon. Southwest flow aloft will persist area-wide keeping sunny
days and clear nights in play from Phoenix west, and high
temperatures will edge downward slightly but remain near seasonal
normals. Low level moisture will still linger in far eastern
Arizona, and the ECMWF suggests that an isolated shower/storm could
be possible east of Globe over the higher terrain, but we will keep
POPs in the single digits east of Phoenix, more along the lines of
the NAEFS numbers.
Monday into Tuesday...both the GFS and the ECMWF agree that the deep
upper trof will push east through the western CONUS with the main
center moving well to our north and across Utah. Strong westerly
flow aloft will affect southern Arizona, keeping conditions dry and
breezy and as heights fall with the trof passage, high temperatures
will fall substantially. Highs over the deserts will drop into the
80s both days with the coolest day in Phoenix expected to be Tuesday
with a high of just 84 degrees for Phoenix Sky Harbor. Normal high
in Phoenix on Tuesday is 93 degrees. Widespread lows well down into
the 50s are likely across the lower deserts, with a few lower 60s
likely in the Phoenix urban core.
Dry subsident northwest flow aloft is expected Wednesday for sunny
days and clear nights and continued below seasonal normal high
temperatures as the deserts remain in the 80s.
&&
.AVIATION...
South-Central Arizona Including KPHX, KIWA, and KSDL:
Shower activity from this morning will continue to dissipate.
However, redevelopment of showers and thunderstorms can be expected
over the eastern third of AZ (mainly east of a TUS-PAN line) and
thus there is some potential for outflow from distant storms with an
easterly component. Couldn`t rule out a stray thunderstorm moving
through the metro late this afternoon and evening but likelihood too
low to reflect in the TAFs. Winds will remain light with a primarily
north-northeasterly component to them, with a very brief period of
north-northwesterly winds after 00Z. Expect scattered to broken
ceilings to remain above 7kft through early this evening, with a
gradual decrease in coverage and increase in ceiling height. Vsbys
to remain in VFR territory, however some patchy blowing dust from
outflow winds is possible this afternoon and evening.
Southeast California/Southwest Arizona including KIPL and KBLH:
Isolated to scattered showers will continue to decrease in coverage
and clear out by 21Z/22Z. Expect ceilings to remain AOA 10kft. Winds
will remain light and favor south and southeasterly directions with
a brief period of westerlies after 05Z.
Aviation Discussion not updated for amended TAFs.
&&
.FIRE WEATHER...
Saturday through Wednesday...
A drier and more stable airmass will spread into the region under
westerly flow aloft. Mostly clear skies are forecast with seasonably
warm afternoon temperatures. Minimum relative humidities will drop
to around 15 percent in southeast California and around 20 to 30
percent in southwest and south-central Arizona on Saturday to 10 to
15 percent areawide on Wednesday. Afternoon southwest winds 5 to 15
mph are expected each day with some afternoon breeziness.
Overnight recoveries will be excellent.
&&
.SPOTTER INFORMATION STATEMENT...
Skywarn radio Net activation will not be needed.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
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DISCUSSION...Percha/CB
AVIATION...AJ
FIRE WEATHER...AJ