Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 09/27/17
Area Forecast Discussion
National Weather Service Caribou ME
957 PM EDT Tue Sep 26 2017
.SYNOPSIS...
A frontal boundary across the north will lift north as a warm
front late tonight. A strong cold front will approach on
Wednesday and cross the area Wednesday night. Canadian high
pressure will build in behind the front Thursday into Friday.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
955 PM Update: Latest radar imagery has shown recent isold to
wdly sct tstm development ovr Ern QB in the St Lawrence Vly W of
the Nrn ME/QB border. Examination of NAM elevated CAPE progs do
show some propagation of elevated CAPE into Nrn ME from Ern QB
so we added isold tstms to the shwrs fcstd ovr this ptn of the
Rgn late tngt. Otherwise, fcst hrly temps/dwpts were updated
thru the late ngt based on trends seen from latest sfc obs, with
fcst lows unchgd attm.
Orgnl Disc: A weak cold front will slowly move southward out of
Canada this evening, making it to as far south as Houlton and
Millinocket before lifting back north later tonight. Hi-res
guidance such as the HRRR and RAP continue to show scattered
showers traveling along this front overnight. The other focus
for tonight will be areas of fog that will lift onshore
overnight. It`ll be another muggy night, especially in those
areas that remain south of the frontal boundary. Northern areas
may get a bit of a reprieve- especially compared to last night-
but it`ll likely still feel a little uncomfortable. Lows will
range from the mid 50s in the Saint John Valley to the mid 60s
in the Central Highlands and interior Downeast.
For Wednesday...a stronger cold front will approach from the west,
bringing a better chance for showers, especially in the afternoon
and evening. Thunderstorms will be possible in the north and west
where SB CAPE is progged to be 500-1000 J/kg. There will be plenty
of low stratus and fog around in the morning, which will help to
keep temperatures a good 10-15 degrees cooler than what we`ve been
experiencing over the past couple of days. Dewpoints will surge back
into the lower and mid 60s though, so the mugginess will continue.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
We will be in a warm humid airmass on Wednesday, but this will be
the last day of the warm humid weather as a strong cold front
approaches from the northwest. The front will push into the north
late Wednesday evening and continue south reaching the coast by
early Thursday morning. A line of rain showers is likely with the
front, especially across the north. Some embedded thunderstorms are
possible. Capes are expected to be close to 500 J/Kg and dynamic
lift with the help of surface convergence may support the
convection. Winds will be strong aloft and any stronger storms could
contain locally gusty winds. The sky will clear behind the front on
Thursday and the air will feel more autumnal as Canada high pressure
begins pushing in from the west. Friday will be very cool with some
stratocumulus limiting sunshine across the north and a mostly sunny
sky Downeast. Highs will only range from the 50s north to 60s
Downeast.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Canadian high pressure will continue to push very chilly air across
the region Friday night into Saturday with dry weather and a sunny
to partly cloudy sky on Saturday. The high will slide south of the
region on Sunday allowing ridging behind the high and a return
southwesterly flow to bring some modification with plenty of
sunshine. Mostly clear and mild weather will continue through early
next week as ridging remains in place along the east coast.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
NEAR TERM: VFR conditions will give way to IFR/LIFR at all
sites overnight, especially the southern terminals, due to low
stratus and fog. Showers will be possible at the northern sites,
as well. Fog will dissipate and ceilings lift gradually after
13z Wednesday, with most sites MVFR by 16z. Showers and
thunderstorms are possible Wednesday, especially in the
afternoon and evening, as a cold front approaches from the west.
SHORT TERM: IFR conditions in rain and some thundershowers are
expected across the north Wednesday night with VFR conditions
lowering to MVFR Downeast. Conditions should improve to VFR
across the north late Wednesday night following the cold frontal
passage. VFR conditions are then expected Thursday through
Saturday with the possible exception of some MVFR conditions in
lower stratocumulus across the far north Friday night.
&&
.MARINE...
NEAR TERM: The Small Craft Advisory remains in effect for tonight and
Wednesday. This is due to long period south swell from Hurricane
Maria. Dense fog is expected to develop again this evening and
linger over the waters into Wednesday morning, reducing visibility
to below 1SM at times.
SHORT TERM: Winds may approach 25 kt in gusts across the
offshore waters Wednesday night and again Thursday night. Seas
Thursday and Friday will be around 6 ft, mainly in S swell from
hurricane Maria. Seas will subside over the weekend.
&&
.TIDES/COASTAL FLOODING...
Currently long period swell from Maria which is running at
13-16 seconds/5-7 feet is affecting the Gulf of Maine. The long
period swell is expected to persist through Wednesday as
Hurricane Marine moves out to sea well to the south of New
England Thursday. Therefore, the High Surf Advisory has been
extended out through Wednesday evening.
Long period waves have a high impact in the surf zone, and can
run up much higher on the shore than shorter period waves
resulting in the danger of spectators being washed into the
ocean. Dangerous rip currents are also expected.
Coastal flooding or beach erosion is not expected at this time.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...High Surf Advisory until 8 PM EDT Wednesday for MEZ029-030.
MARINE...Small Craft Advisory for hazardous seas until 8 PM EDT
Wednesday for ANZ050>052.
&&
$$
Near Term...VJN
Short Term...Bloomer
Long Term...Bloomer
Aviation...VJN/Bloomer
Marine...VJN/Bloomer
Tides/Coastal Flooding...
Area Forecast Discussion
National Weather Service Charleston SC
1032 PM EDT Tue Sep 26 2017
.SYNOPSIS...
Tropical Storm Maria will continue to track off the Mid
Atlantic coast through late week. A cold front will move
through the area by early this weekend, followed by high
pressure into early next week.
&&
.NEAR TERM /THROUGH WEDNESDAY/...
As of 1020 PM: KCLX detected a few clusters of light showers
moving across portions of the outer GA waters. I will update the
forecast to increase PoPs to SCHC across AMZ374 through
midnight. HRRR suggests that another round of showers will
develop across the inland GA counties late tonight ahead of a
passing vort max. Latest water vapor images indicate that a
disturbance was crossing the lower Savannah River Valley at
230z. However, with loss of heating it seems that any showers
that develop would be very weak. We will continue to monitor the
Coastal Plain for any additional showers.
As of 9 PM: Temperatures continue to run a little warmer than
expected. I will issue a quick update to adjust late evening
temperatures up a degree or two.
As of 715 PM: Radar trends indicate that upstream showers have
generally dissipated. Temperatures still remain warm from
daytime maxes. I will update to indicate warmer temperatures
through the late evening hours.
As of 615 PM: KCLX detected a few sprinkles passing over
portions of Berkeley, Dorchester, and Colleton Counties about a
half hour ago. Recently, a few weaken showers were detected
upstream across the Pee Dee region. It appears that the
upstream showers will struggle to reach south of Lake Marion.
Visible satellite very little in associated sky cover across the
region. I will update the forecast to adjust sky, populate
hourly temps with observations, and increase PoPs into the lower
teens.
Previous discussion:
A dry, downslope flow will remain place tonight as Hurricane
Maria meanders offshore of the North Carolina Outer Banks.
Expect dry conditions continue through daybreak with diurnal
cumulus quickly dissipating after sunset yielding clear to
mostly clear skies. The boundary layer looks to decouple later
this evening with lows ranging from the upper 60s well inland to
the mid 70s at the beaches.
&&
.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
A broad upper level ridge to our west Wednesday into Thursday
will maintain dry conditions and well above-normal temperatures.
With highs in the lower 90s we will only be a few degrees away
from daily records.
The development of an upper low over the eastern Gulf of Mexico
will result in the upper ridge retrograding and a relatively
zonal flow setting up over the eastern United States.
Reinforcing Canadian high pressure will move into the Great
Lakes on Friday and push a cold front into the area. Though
moisture and forcing will be limited, there could be enough
ascent to produce isolated showers or tstms across the area on
Friday. Slightly cooler temperatures will affect far northern
areas though little to no cold advection will reach the majority
of the area during the day. Thus highs will again reach the
lower 90s most areas.
&&
.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
High surface pressure will begin filling back into the area later
Friday into the weekend behind the departing cold front. Elevated
probabilities for precipitation will linger behind frontal passage
as a sharpening upper level trough crosses the forecast area
Saturday. Ridging aloft will follow this feature and a weak high
pressure wedge-type pattern could set up near or just inland from
the area later Saturday into Sunday and persist into early next
week.
&&
.AVIATION /03Z WEDNESDAY THROUGH SUNDAY/...
VFR through the 0Z TAF period for both KCHS and KSAV.
Extended Aviation Outlook: Mainly VFR conditions are expected.
&&
.MARINE...
Tonight: Seas have subsided enough at buoy 41004 to cancel the
Small Craft Advisory for the Charleston County waters. Seas will
remain above 6 ft over the Georgia offshore waters where the
Small Craft Advisory remains in effect. Northwest winds will
continue with seas ranging from 2-4 ft nearshore waters to 5-7
ft offshore waters.
Wednesday through Sunday: Seas will continue to steadily
subside on Wednesday with Small Craft Advisory conditions ending
by midday over the offshore GA waters. For the remainder of
Wednesday through Friday, rather tranquil conditions will exist
with weak high pressure building from the northwest.
Northeast winds will begin increasing early Saturday in
response to a tightening pressure gradient, peaking around 20
knots with gusts to 25 knots, and seas increasing in response.
Small Craft Advisory conditions will be possible again by
Saturday afternoon and could persist into early next week.
Rip Currents: With a strong pinching of winds and the resulting
increase in seas this weekend, another round of enhanced rip
current risk seems likely.
&&
.CLIMATE...
Record highs for 28 September:
KCHS: 94/1986.
KCXM: 92/1986.
KSAV: 98/1986.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...Small Craft Advisory until 4 PM EDT Wednesday for AMZ374.
&&
$$
NEAR TERM...NED
SHORT TERM...
LONG TERM...
AVIATION...NED
MARINE...
CLIMATE...
Area Forecast Discussion
National Weather Service Dodge City KS
600 PM CDT Tue Sep 26 2017
...Updated Aviation...
.SHORT TERM...(This evening through Wednesday)
Issued at 314 PM CDT Tue Sep 26 2017
Broad surface high pressure across the Northern Rockies extending
through western Kansas and into the panhandles will continue to
provide north to easterly surface winds tonight. The low level post
frontal stratus has begun to partially mix out this afternoon,
lifting ceilings as insolation indirectly warmed the cloud layer in
this neutral temperature tendency boundary layer. Latest HRRR is
quick to redevelop the lower clouds behind this front this evening
with quite low ceilings, however that`s in contrast to the HiRes
NMM/ARW as well as the SREF probabilities for the low clouds. Most
residual cloud cover will likely remain Mvfr or VFR across the
southern 2/3rds of the area. There is not a large spread in the
various model overnight lows, however there is much support for
widespread 40`s, with even low 40s possible in the far western
sections of Kansas. Warmer highs are expected Wednesday, however
still about 10 climatological degrees cooler, in the low
70s/upper 60s with light northeast winds.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 314 PM CDT Tue Sep 26 2017
Fall like temperatures are expected through the week as cool
recirculated air from the current broad surface high influences
southwest Kansas. Consensus of models indicates a more
substantiated warming by the end of the week as the surface winds
increase out of the south and southwest, with highs in the 80s
probable by the weekend. The best chances for some more showers
and thunderstorms returns Thursday night, which may be a result of
a lead wave associated with the next significant upper low to
develop over the western States. Additional chances for storms in
the western will continue through the weekend as the upper low
lifts into the northern plains, and the high plains from Colorado
into New Mexico becomes convectively unstable each afternoon with
generally a mean southwest steering flow.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 600 PM CDT Tue Sep 26 2017
MVFR stratus cigs will persist through the night into early
Wednesday morning, including LBL, GCK and DDC. Consensus of short
term models keeps stratus out of the HYS terminal. Reductions in
surface visibility are not expected. Surface high pressure ridge
will hold firm through 12z Wed, with 1025 mb surface high centered
near Concordia. Light N/NE winds will prevail tonight. Surface
high remains centered over northern Kansas through Wednesday
afternoon, keeping winds NE near 10 kts at all airports. Expect
lifting cigs and an erosion of the stratus after 15z Wed.
&&
.PRELIMINARY POINT TEMPS/POPS...
DDC 49 69 49 70 / 10 10 10 20
GCK 45 68 49 66 / 0 10 10 30
EHA 45 64 47 60 / 10 20 20 50
LBL 47 65 49 66 / 10 20 10 40
HYS 47 68 49 71 / 10 0 0 10
P28 54 69 53 74 / 20 20 0 10
&&
.DDC WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM...Russell
LONG TERM...Russell
AVIATION...Turner
Area Forecast Discussion
National Weather Service Marquette MI
757 PM EDT Tue Sep 26 2017
.SHORT TERM...(This evening through Wednesday)
Issued at 318 PM EDT TUE SEP 26 2017
WV imagery and RAP analysis indicated a mid/upper level trough over
the Dakotas moving slowly ne toward the Upper Great Lakes. Southwest
flow prevailed through the western Great Lakes between the trough
and a ridge over the eastern Great Lakes and mid Atlantic states. At
the surface, a broad area of low pressure extended from Upper Mi
into nw IL. Strong 850 mb moisture transport was supporting
scattered showers across Upper Mi early this afternoon ahead of the
mid-level trough despite only weak q-vector convergence and fairly
weak instability (a few hundred j/kg at best).
RAP model shows MUCAPE values to near 500 j/kg into central and
eastern Upper Mi late afternoon into early evening and increasing
effective shear to around 40 knots which could lend support for some
stronger storms with small hail possible over the east half of Upper
Mi into early evening.
Tonight and Wednesday, Q-vector convergence ahead of the mid-level
trough could keep some lingering showers and isolated t-storms over
the east half during the evening but expect convection to diminish
quickly overnight as cooler/drier air moves in behind the front.
There may be enough low level moisture along with increasing upslope
wnw flow and 8h temps lowering near 0c per NAM soundings to support
the development of isolated to scattered lake effect rain showers
over the west and eastern counties late tonight into Wed, mainly
over the higher terrain. Otherwise, a surface ridge and drier air
will push into the area on late tonight into Wed which will lead to
mainly drier conditions across much of the area under near normal
temperatures. Lows tonight will be in the 40s to lower 50s. Highs
Wed will be in the mid 50s to lower 60s.
.LONG TERM...(Wednesday night through Tuesday)
Issued at 334 PM EDT TUE SEP 26 2017
Upper level troughing downstream of large upper ridge over western
Conus and western Canada will bring cool down to Upper Great Lakes
rest of the week. Cool down looks brief though as sfc to upper
level ridging for the weekend will bring a return to above normal
temperatures and mainly dry conditions. Appears that warmer than
normal conditions will continue through first week of October as
broad upper ridge dominates much of the Conus.
Low pressure system bringing the showers into Wed will move to
eastern Canada Wed night into Thu. Soundings show gradual drying in
by late aftn which should end lingering showers, but bkn-ovc
stratocu clouds should still linger into Wed evening before
clearing occurs overnight Wed night. Shortwave and re-inforcing sfc
trough moves through Thu aftn into Thu evening. Weak thermal ridge
ahead of trough along with some sunshine may lead to highs bumping
into the 60s ahead of trough, but with cold air advection behind
the trough expect gusty north winds up to 25 mph to usher in temps
mainly in the 50s on Friday. Moisture ahead of trough is limited so
rain chances on Thu look low. Better chance of light rain occurs
late Thu night into Friday over the north forecast area for upslope
favored areas as cooler/moist cyclonic flow develops behind the
trough. Subsidence and drying with approaching high pressure system
should diminish and end any rain later Fri into Fri evening.
High pressure settling overhead Fri night and dry air advection with
pwats as low as 0.3 inches opens door for frost potential inland
where lighter winds are expected through the night. Various bias
corrected guidance indicates min temps in the upper 20s to lower 30s
for the favored cold spots.
Warm up then begins Saturday as the high shifts east and southerly
return flow develops between departing high and large low pressure
system tracking across south central Canada. Highs on Saturday
should be in the 60s with highs on Sunday possibly reaching the 70s
at least over the west. Increasing chances for showers and possible
thunderstorms on Monday as leading front ahead of large low
approaches the region. Temps remain warm aloft though so if clouds
and rain are not widespread, could see highs in the 70s for even
more of the area. Even in wake of the trough early to mid next week,
temps should still remain well above normal with even more 70s
possible as there is not much cold air advection expected behind the
trough. Based on h85 temp anamolies from the GFS and ECMWF ensembles
would not even be surprised to see temps crack 80F sometime next
week.
&&
.AVIATION...(For the 00Z TAFS through 00Z Wednesday evening)
Issued at 757 PM EDT TUE SEP 26 2017
With a low pressure system exiting the area while a ridge of high
pressure moves in, conditions will improve through the forecast
period.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 318 PM EDT TUE SEP 26 2017
Ne winds diminishing over western Lake Superior this afternoon as
low pressure and associated frontal boundary lift into central Upper
Mi. Winds will remain lighter over eastern Lake Superior. As the low
lifts ne of Lake Superior later this evening, w to nw winds will
increase to 20-30kt across the lake late tonight into Wed with the
strongest winds over east half of Lake Superior. Would not be
shocked to see a few gale gusts to 35 knots at higher platform
stations like Stannard Rock. Winds will diminish to mostly under
20kt or less Wed night into Thu as no strong systems are expected to
impact the Upper Great Lakes. A low pres trough swinging se across
the Upper Great Lakes Thu night will usher in another round of 15-
25kt winds on Fri. Winds will then diminish to under 20kt Fri night
for Sat as high pressure moves over the area.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.
&&
$$
SHORT TERM...Voss
LONG TERM...JLA
AVIATION...Titus
MARINE...Voss