Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/01/17
Area Forecast Discussion
National Weather Service Columbia SC
608 PM EST Thu Nov 30 2017
A weak cold front will move into the area tonight. The front
will stall and remain in the region through Saturday. The front
will move off the coast Saturday night with high pressure moving
into the region Sunday. A stronger cold front will approach by
the middle of next week.
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
A cold front currently moving into the Ohio and Tennessee
Valleys will move into the forecast area overnight.
Convergence associated with the front plus lift associated with
the left exit region of an h25 jet supports a chance of showers.
Coverage may be limited because of diminished moisture in an
h85 westerly flow. Models begin taking the deeper moisture east
by daybreak, so have pops gradually diminishing from west to
east. Leaned toward the higher temperature guidance because of
mixing associated with the front.
.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
Front pushes through the majority of the forecast area by early
Friday morning. Any rainfall associated with the front should
have pushed east of the area, and be diminishing as it moves
out. High pressure will move north of the FA, with a
northeasterly surface wind pattern shaping up. However, aloft
an onshore flow pattern will develop. This may help to bring
isentropic lift and just enough moisture back across the
southernmost portions of the cwa Friday night into Saturday, and
thus may cause a few scattered showers to form once again
across the FA. Conditions should dry out once again by Saturday
night. Temperatures Friday will be about 10 degrees cooler than
previous day, with additional cooling expected to occur for
.LONG TERM /SUNDAY THROUGH THURSDAY/...
Sunday through what looks like Tuesday should be dry as high
pressure will be over the majority of the area. Temperatures
will once again rise to above normal levels Sunday through
Wednesday. Models then indicate a digging upper level system
will begin to carve out a deepening East coast trough beginning
Wednesday into Thursday. Models do differ on the exact timing
that far out, but a strong cold front is expected to push
through the region near the end of the longer term period. A
return to much colder air will occur behind the front.
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
VFR conditions early this evening. Restrictions expected late
tonight and Friday morning as a frontal boundary moves into the
area and low-level moisture increases.
Mainly mid level ceilings early this evening with lowering
ceilings after midnight. The latest HRRR and LAMP guidance
suggests MVFR strato-cu developing across the CSRA toward
morning and spreading into central SC. Some upper level
clearing after 10z may result in fog development but confidence
low. Think MVFR ceilings dominate through 16z with a period of
IFR possible. Lowest threat for significant restrictions appears
to be OGB as low level moisture flux west of that terminal.
Improving ceilings to VFR expected by afternoon with drying in
the low levels. Winds will be light and variable.
A cold front will move into the forecast area tonight bringing a
chance of showers to the terminals. Coverage may be limited
because of diminished moisture in an h85 westerly flow. The
chance of showers was too low to include in the terminal
forecasts at this time. MVFR or IFR conditions are expected to
develop overnight due to lingering low-level moisture near the
front combined with nocturnal cooling and drying aloft behind a
shortwave trough. The pressure gradient associated with the
front will be weak and expect continued light wind tonight.
Models indicate visibilities returning to VFR by mid Friday
morning with winds picking up slightly. Most of the model
guidance shows IFR ceilings returning to MVFR by mid morning and
remaining MVFR through the end of the 24-hr TAF period.
EXTENDED AVIATION OUTLOOK...IFR or MVFR conditions may occur
at times through Saturday associated with a front lingering
near the area. It should be drier Sunday and Monday with ridging
Area Forecast Discussion
National Weather Service Cleveland OH
942 PM EST Thu Nov 30 2017
A large area of high pressure will move across the area tonight
into Friday then persist into Saturday. A weak cold front will
move across the region Saturday night. High pressure then
reestablishes itself over the area for Sunday.
.NEAR TERM /THROUGH FRIDAY NIGHT/...
Update...Removed slight chance pops nwrn PA. Also made minor
hourly temp adjustments and adjusted overnight cloud cover up a
bit in nern OH and nwrn PA based on satellite trends and 850mb
moisture progression on RUC model.
Original...Cold front is quickly moving eastward across the
region and should be east of the County Warning Area by 23Z.
Expect all the rain to move eastward with it. Skies will
continue to clear from west to east but it will likely slow this
progression across NE OH/NW PA with flow developing off of Lake
Erie. High pressure will then take control of the area by
Friday morning and persist into Friday night.
Seasonal temperatures are expected through the the near term.
.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
High pressure will remain established over the area through
Sunday, slowly drifting east Sunday night into Monday. This will
keep conditions dry through this period, with temperatures
slowly warming from the upper 40s for highs Saturday to the low
to mid 50s by Monday. Dry conditions are expected through early
Monday, but will keep slight chance/chance pops in the forecast
Monday in advance of a cold front/deepening low. The models may
be slowing down a bit with this system, which may end up leading
to dry conditions through the entire daytime hours.
.LONG TERM /MONDAY THROUGH THURSDAY/...
Much colder air still on tap for the long term as deep trough
digs over the forecast area. Will see the coldest air of the
season with highs only in the lower to mid 30s and lows in the
lower to mid 20s.
Models continue to differ somewhat on the precise timing of the
approaching systems. Models continue to push first cold front
across the forecast area Monday night into Tuesday. The ECMWF
continues to be the faster of the 2 models pushing the initial
front through by Tuesday morning. The GFS however develops a low
on the boundary which stalls the front over the area into
Tuesday night. GFS has the secondary arctic boundary catching up
and pushing through Wednesday morning. The ECMWF on the other
hand pushes the first front through Tuesday with a break then
the arctic boundary going through Wednesday evening. For the
forecast leaned toward ECMWF as it is much closer to continuity.
Either way Lake effect snow develops in the snowbelt by Wednesday
night as the 850mb temps plunge to -13c. How much snow will
depend on which model you believe. The GFS has a ridge of high
pressure build over the area Thursday night while the ECMWF has
a secondary trough move across the forecast area Thursday night.
For now used a model blend for temps and pops for Thursday.
.AVIATION /00Z Friday THROUGH Tuesday/...
Post cold front clearing moving in across much of the area with
the exception of nwrn pa and nern OH. Will continue with clear
skies through the night and into Friday most areas. For KYNG
will hold into a low VFR cig through the evening. For KERI will
keep a low VFR cig through the night. Otherwise with all of the
area having rain today and given that winds will be light and
skies mostly clear, have placed mostly MVFR fog in TAFS
overnight away from Lake Erie.
OUTLOOK..Non-VFR may return Saturday night across NE OH/NW PA
in the wake of a weak cold front.
A cold front will push east of Lake Erie by this evening. Winds will
begin to shift to the northwest tonight, with small craft conditions
expected from Cleveland east through most of the night. Winds will
back off to 10 knots or less by Friday morning. High pressure will
build across the region Friday and will remain in control through
the weekend into early next week. Winds will remain southerly to
westerly during this period, with some diurnal rises to near 15 kts
or so. Winds will increase to 20 kts out of the south Monday night
into Tuesday as low pressure deepens and moves into the central
lakes, forcing a cold front across Lake Erie.
MARINE...Small Craft Advisory until 9 AM EST Friday for LEZ146>149.
Area Forecast Discussion
National Weather Service Jacksonville FL
945 PM EST Thu Nov 30 2017
Weak sfc high pressure is over the forecast region but a weak cold
frontal boundary is sagging southeast across wrn NC to central AL
through southeast LA. The front should move to near an Augusta GA to
Ft Walton Beach FL line by 12z Friday. A shortwave trough is across
the TN valley southwest to nrn LA and is generating some isolated to
scattered patches of rain from west central GA southwest to the wrn
FL panhandle. Satellite imagery shows partly to mostly cloudy skies
now beginning to impinge on our northwest to western counties ahead
of the shortwave trough. Otherwise...skies mostly clear with temps
dropping into the 50s in some areas with light to calm winds.
For the update...only minor changes to the min temps in the 50s to
around 60...being a little warmer tonight than last night due to
increased cloudiness. Have brought in a bit more precip to the nrn
zones based on GFS and HRRR runs but staying with about 20 percent
rain chances as QPF will be pretty light...probably at or below
about .02" into early Friday morning. Prospects for areas of
fog...some of it dense...still on track for mainly the east and
primarily southeast zones where clouds will have less impact on
cooling trends overnight. This is also where the SREF guidance has
the highest fog chances...though lower chance than it was for last
.AVIATION...Prevailing VFR up until ~ 06z-08z but then anticipate
VSBY conditions especially for the NE FL tafs with MVFR beginning.
Chance of IFR or lower for CRG, VQQ and JAX toward early morning but
put in a fairly short TEMPO window as mid level clouds will be
moving in as well. conditions should improve to VFR all TAFS through
the mid morning hours but with cigs around the 8-10k level expected.
A light shower possible near SSI toward early morning but basically
no sig wx impact.
.MARINE...Only minor edits for winds tonight that are at or below
10 kt. Seas forecast looks on track. Some patchy fog possible
near/along the coast after midnight.
.PRELIMINARY POINT TEMPS/POPS...
AMG 55 76 55 72 / 20 20 20 20
SSI 58 74 58 70 / 20 10 10 10
JAX 54 78 56 76 / 0 10 10 10
SGJ 53 75 58 74 / 0 0 10 10
GNV 52 78 55 77 / 0 0 10 10
OCF 54 80 56 77 / 0 0 10 10
Area Forecast Discussion
National Weather Service Melbourne FL
833 PM EST Thu Nov 30 2017
Tonight...Surface high pressure ridge over north Florida will cause
onshore flow to diminish, especially across our northern areas.
There`s been a persistent north/northeast flow down the Gulf Stream
this afternoon/evening, which has brought a few showers into the
Treasure Coast. Expect a recent decreasing trend to continue as the
gradient wind slowly eases and drier air filters down the peninsula,
so any south coastal rain chances look brief.
Mostly clear skies and light winds should promote fog development
late tonight, especially across the north interior. Slight drying
has occurred in the lower levels, but low temps will be a few
degrees cooler, so expect at least patchy fog. The latest MOS
guidance and NAM support fog formation, though the HRRR doesn`t
develop any again (but it was wrong last night). Won`t be making any
changes to the current forecast.
Weak to light northerly flow, combined with a little drier air than
24 hours ago, will produce overnight mins a few degrees lower than
this morning. Even the Treasure Coast should have mins a few
degrees lower in the mid-upper 60s.
Guidance continues to indicate a chance for late night fog across
the interior terminals. Therefore have made no changes to the
previous TAFs. Low level winds will be lighter early Fri morning,
but still expect fog to diminish quite quickly in the 13-14z time
Tonight-Friday...Surface high pressure ridge across north Florida
will produce a diminishing northeast flow, except northerly along
the coast. Speeds already look 10 knots or less across the northern
waters. 10-15 knots should hold on in the southern waters through
the night. Seas up to 3 feet near shore and 4-5 feet in the Gulf
Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
907 PM CST Thu Nov 30 2017
.DISCUSSION...See updated information for land and marine areas
.UPDATE...Regional radar imagery indicates that scattered to
locally numerous rain showers associated with a shortwave trough
have moved east and are mainly impacting south central Alabama as
of 9 PM CST. Showers should gradually decrease in coverage through
the late evening and overnight hours, but will leave a low rain
chance in the forecast over the eastern zones overnight as
residual moisture and weak lift remains in place across this
portion of the region ahead of a slow moving cold front.
Areas of dense fog will otherwise be the primary significant
weather impact late tonight into early Friday morning. Surface
observations and 11-3.9u satellite imagery indicate that areas of
dense fog are already forming northwest of a Wiggins, MS to
Camden, AL line right now where moist ground, a shallow saturated
airmass in the low levels, and decreasing upper level clouds are
favoring development. HRRR and SREF probabilities lend confidence
that areas of fog will develop east-southeast with time across
most of the remainder of the area through early Friday morning,
so have issued a Dense Fog Advisory for the entire CWA through 9
AM Friday morning. Forecast updates have been sent. /21
.MARINE...Areas of dense marine fog are likely to develop at
least over Mobile Bay and the Mississippi Sound again late this
evening through early Friday morning, so have issued a Dense Fog
Advisory for these marine zones until 9 AM. /21
.PREV DISCUSSION... /issued 613 PM CST Thu Nov 30 2017/
DISCUSSION...Updated for latest aviation discussion below.
00Z issuance...Scattered to numerous SHRA and associated localized
MVFR to IFR cigs/visibility reductions will continue to push east
of the I-65 corridor through the evening hours. Conditions are
also now looking more favorable for the development of areas of
fog and low ceilings across much of the region late this evening
through Friday morning. IFR to LIFR ceilings are expected to
develop, while visibility may also become reduced to LIFR or lower
levels at times mainly after 03-06z. A light northwesterly to
northerly wind returns this evening/late tonight following the
passage of a weak cold front. /21
PREV DISCUSSION... /issued 356 PM CST Thu Nov 30 2017/
NEAR TERM /Now Through Friday/...Scattered to locally numerous
showers will continue to move east across the Gulf coast this
afternoon through the late evening ahead of an approaching cold
front. The rain will end from west to east overnight as the front
moves southward into the marine area Friday morning. No thunder is
expected due to weak forcing and little instability. Rainfall
amounts will be light, generally less than one-quarter of an inch.
Ahead of the front, areas of fog will again be possible tonight.
However, confidence is low in widespread dense fog due to the clouds
and showers, but patchy dense is possible. Lows tonight will remain
well above normal in the low to mid 50s. Clouds and rain will
gradually clear the area Friday morning as the cold front moves into
the marine area and high pressure builds in. Highs will climb into
the upper 60s and low 70s. /13
SHORT TERM /Friday night Through Sunday night/...A broad upper
ridge over the south central states expands northward across the
remainder of the central states through Saturday night. The upper
ridge amplifies while continuing eastward into the eastern through
Sunday night. A large surface ridge centered over the interior
eastern states persists through Saturday night, then weakens
Sunday into Sunday night as a cold front advances across the
Plains. This pattern will maintain a light northerly flow over the
forecast area through much of the period before finally switching
to a southeasterly direction Sunday night. Within the larger
scale upper level pattern, am embedded shortwave trof advances
across Texas Saturday night into Sunday then weakens as it moves
to near the lower Mississippi river valley late Sunday night. At
this time, this feature looks to weaken sufficiently so as to
continue with a dry forecast through the period. /29
LONG TERM /Monday Through Thursday/...An evolving longwave trof
advances across the Plains through Tuesday, which also has a
positive tilt portending the potential for ejected shortwaves to
advance downstream and across the forecast area. The large upper
trof eventually amplifies further while continuing eastward into
the eastern states through Thursday. A cold front advances from
the Plains early in the period and moves through the forecast area
Tuesday night, although there is some uncertainty with passage
possible as early as early Tuesday evening or as late as Wednesday
morning. Deep layer moisture increases to well above
climatological normals ahead of the approaching front, with
precipitable water values reaching around 1.8 inches immediately
ahead of the front. These values are about 200% of normal for this
time of year. Small pops return mainly to the western portion
forecast area Monday into Monday night, then increase to chance to
good chance on Tuesday as a series of ejected shortwaves move
across the area ahead of the approaching front. Similar pops
follow for Tuesday night with the passage of the front.
Tuesday continues to be a challenging forecast period. There is
some potential for CAPE values of 300 J/kg over the eastern
portion of the area trending to CAPE values of near 500 J/kg
almost becoming likely over southeast Mississippi. In addition,
model soundings show a shallow cap near 800 mb which if overcome
would result in increased CAPE values, perhaps an additional
300-500 J/kg. A veering profile is evident below 800 mb, but the
latest guidance keeps helicity values near 100 m2/s2. Abundant low
level moisture is present below the shallow cap, while dewpoint
depressions of up to 20F exist further aloft and will
significantly aid downdraft production for convection that breaks
through the cap. Considering this environment, there still exists
at least a low end potential for strong storms on Tuesday, and an
isolated severe storm still cannot be ruled out, so will maintain
current wording in the Hazardous Weather Outlook. That said, the
potential now looks to be more over the western portion of the
area but will continue to monitor.
The remainder of the forecast period is another forecast challenge
as well due to uncertainties regarding the strength and duration
of an overrunning flow that continues across the forecast area in
the wake of the front. This occurs as much cooler air flows into
the forecast area with temperatures dropping into the mid 30s over
much of the interior area Wednesday night, along with the 1300
meter 1000-850 mb thickness line dropping to just north of the
coastal counties. Am thinking that drier air will work into the
region to stop the precipitation before a change over to wintry
precipitation could occur - but this will have to be closely
monitored. So, will have good chance pops for the entire area on
Wednesday, then pops taper off to dry conditions before
temperatures drop off sufficiently to change the precipitation
over to a mix. /29
in the low levels
AL...Dense Fog Advisory until 9 AM CST Friday for ALZ051>055.
Dense Fog Advisory until 9 AM CST Friday for ALZ056>060-261>266.
FL...Dense Fog Advisory until 9 AM CST Friday for FLZ201>205.
MS...Dense Fog Advisory until 9 AM CST Friday for MSZ067-075-076-078-
GM...Dense Fog Advisory until 9 AM CST Friday for GMZ630>632.
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Area Forecast Discussion
National Weather Service New York NY
924 PM EST Thu Nov 30 2017
A cold front moves through late tonight. High pressure builds and
will remain along the east coast through the beginning of next
week. A frontal system will impact the area during the mid week
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Forecast is on track. Just minor adjustments to PoPs and hourly
T/Td as temps are holding steady a bit longer than expected.
Most areas should measure even though some values may only be a
hundredth or so.
Otherwise, models in good agreement in handling upper shortwave
and sfc cold front tonight. Upper shortwave moves across the
area tonight, with upper jet passing well to the north. Lift is
weak, and moisture is lacking for any significant showers.
Expect a brief line moving through with best chance for light
measurable remaining across the NW zones, with some weakening as
the line moves east ahead of the cold front. Pcpn should start
to clear NW zones 3-4Z, and SE CT and Eastern LI by 10-11Z. Any
qpf remains under a tenth of an inch, with minimal amounts
expected closer to the coast. HRRR simulated radar reflects this
Temps should fall toward morning behind the front. Lows likely
range from the middle 40s coast/NYC metro to the lower 30s by
daybreak after the showers pass inland. Followed a blend of the
MAV/MET and ECS guidance.
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Shortwave passes in the morning with ridge building behind. Plenty
of sunshine is expected, with perhaps a few high clouds encroaching
from the west Friday night.
Temps a MOS blend with highs in the 50 to 55 degree range after weak
CAA ends. NW winds pick up as the pressure gradient tightens, and
gusts 20 to 25 mph are possible for a few hours between the front
and building high.
At night, lows will range from the lower 20s to the upper 30s as
north winds abate and skies remain mostly clear, allowing
radiational cooling to take place late.
.LONG TERM /SATURDAY THROUGH THURSDAY/...
Zonal flow at the start of the long range period will give way to a
much more amplified pattern with a full latitude trough impacting
the area by the middle of next week.
With a surface high centered over the east coast on Saturday and
Sunday, dry and seasonable conditions are expected for the weekend.
A shortwave passing to the north on Sunday will result in an
increase in cloud cover during the afternoon, but with little
moisture to work with, this is expected to be the only impact.
The high begins to move offshore on Monday as the flow aloft
amplifies with an upper ridge building along the east coast in
response to a trough digging into the western U.S. Models remain in
generally good agreement with the idea of the associated surface low
and cold front progressing across the central CONUS on Monday before
impacting the local area during the mid week period, but differences
in the timing and evolution of this system remain. The ECMWF
continues to advertise a faster frontal passage, bringing rain into
the area during the day on Tuesday, while the GFS keeps the majority
of the area dry until late Tuesday night. Given the uncertainty,
continued with chance PoPs for much of the day on Tuesday into
Wednesday before drying the area out behind the system on Thursday.
Another complication is how far east of the area the front is able
to progress on Wednesday/Thursday, as models continue to indicate
the potential for a wave to develop along the front late in the
period, which could prolong any precipitation.
Temperatures on Monday will be near normal before rising above
normal on Tuesday and Wednesday as southwesterly flow increases
ahead of the front. Temperatures behind the front on Thursday will
be near to a few degrees below normal, in the mid 40s. With strong
warm air advection ahead of the front, the majority of the
precipitation with the mid-week system is expected to fall in the
form of rain, although a few snow showers or a rain/snow mix is
possible north and west of NYC on Thursday as the precipitation
comes to an end.
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
A cold front moves across the region late tonight followed by
high pressure for Friday.
Some pockets of stratus around 2500 ft are possible ahead of
approaching showers, but should not prevail. Otherwise, showers
will quickly move through tonight from west to east. They should
only last for a few hours. After the showers end, MVFR ceilings
around 3000 ft are expected before a return to VFR before day
Increasing southerly flow under 10 kt will gradually veer to
the SW-W after midnight and then NW by early Friday morning.
Timing of wind shifts may be off 1-2 hours from forecast.
Gusty NW flow is expected late Friday morning into the
.OUTLOOK FOR 00Z SATURDAY THROUGH TUESDAY...
.Tue...MVFR possible in showers.
South winds increase ahead of a cold front tonight. Speeds of 15 to
20 kt are possible, especially on the ocean. Then winds shift around
to the NW late tonight/Friday morning. Speeds remain around 15 kt
with gusts around 20 kt. A few gusts could approach or reach 25
kt, but feel this will be brief. As such, no headlines planned
after collaboration with surrounding offices.
NW/N winds diminish Friday night as high pressure approaches
from the west. Seas on the ocean remain 4 ft or less per
guidance, and 2 ft or less on the non ocean waters surrounding
Quiet conditions are expected on the waters this weekend into early
next week as high pressure remains in place along the east coast.
Winds will begin to increase during the day on Tuesday as
southwesterly flow increases ahead of an approaching cold front,
with gusts approaching SCA criteria late. In addition, seas on the
ocean waters will increase to 5 ft by Tuesday afternoon.
No significant hydrologic impacts are expected.
NOAA Weather Radio Station KWO-35 operating on a frequency of 162.55
mHz in New York City is OFF THE AIR for an extended period of time.
See our headline news on the web (weather.gov/nyc).