Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 12/03/18
Area Forecast Discussion
National Weather Service Cleveland OH
1023 PM EST Sun Dec 2 2018
.SYNOPSIS...
Low pressure centered over the middle Mississippi River will
follow closely behind the front and move through the central
Great Lakes tonight and into Canada for Monday. The associated
cold front will move through the area on Monday. High pressure
attempts to slowly build in from the west for mid-week. Another
cold front will move across the region on Thursday.
&&
.NEAR TERM /THROUGH MONDAY/...
Cold front has shifted east of the area and both the threat of
thunderstorms and severe weather has ended. A band of showers is
moving across NE Ohio and NW Pennsylvania ahead of the upper
level wave. These will move east out of the area after midnight,
leaving just a low chance of showers as the wrap around moisture
and low level trough slide east. Temperatures are falling
quickly behind the front, already in the lower 40s across most
of NW Ohio.
Previous discussion... It is a fantastic mild and breezy Sunday
afternoon. But there is usually a price to pay for this nice
weather for this time of year. Hi-res guidance and forecast
models suggest a little bit of active weather late this
afternoon into early this evening. There are no changes to the
previous mesoscale discussion written earlier today. We are
watching closely the area from a line near Elyria south to
Wooster eastward across northeast Ohio into northwest
Pennsylvania between 4 pm and 9 pm. Convection will start to
develop across northwestern Ohio between 3 and 4 pm. These
storms will move quickly eastward at nearly 40 to 50 mph and a
few of them will become severe by the time they reach the I-71
corridor. Damaging winds up to 65 mph will be the main threat
followed by small hail up to nickel size. Given the very high
shear in the low levels of the boundary layer, we can`t rule out
an isolated tornado threat. Usually, when we have high shear
but low instability this time of year...we see low top
supercells and mini bow like structures.
We expect most if not all the storms to be weakening and east of
our NW Pennsylvania counties by 9 pm this evening. Scattered
light showers will be around tonight and temperatures will
begin to fall as winds become more westerly. A secondary cold
front will move through Monday morning and change our winds more
northerly by midday and afternoon. Temperatures will continue to
fall slowly during the day. We will see rain showers change to
snow showers during the afternoon. Snow showers could be
moderate at times especially in the primary and secondary
Snowbelt region down wind of the lake and higher elevations. It
will take a while before snow will be able to accumulate because
of the warm ground and temperatures around freezing. Lake effect
snow showers will continue across northeast Ohio and northwest
Pennsylvania Monday night. We will likely see some light
accumulations after sunset and as temperatures fall into the
upper 20s. 1 to 2 inches will be possible in primary and
secondary Snowbelts. Isolated higher amounts could be possible
in primary Snowbelt areas.
Previous mesoscale discussion...
We have been looking at the newest Hi-Res model data this
morning for the storm threat late this afternoon and evening. We
are seeing the potential for MUCape to develop between 400 and
700 J/KG thanks to all the extra sunshine and temperatures
expected to reach the low to mid 60s this afternoon. One note to
point out is that forecast low level CAPE 0-1km is around 100
to 200 J/KG which is concerning. 0-1km helicity values are
running about 200 to 500. 0-6km Bulk shear magnitudes are in
the 50 to 70 knots. Surface winds just along the surging front
will be about 170 to 190 degrees. With these given parameters,
we do expect a few low topped supercell like storms right along
the front across northern Ohio into NW Pennsylvania. We really
like the the way the HRRR and 4km NAM has for timing of
development and evolution of this potential severe weather
event. There will be a damaging winds and isolated tornado
threat. We will see CU and convection development just east of
Toledo down to Lima, Ohio between 3 pm and 4 pm. Strong to
severe convection from near Lorain County to Mansfield area by 5
pm. The Cleveland area down the I-71 corridor between 5 and 6
pm. NE Ohio to Akron/Canton area between 7 and 8 pm and NW
Pennsylvania between 8 pm and 9 pm. That is our best
expectations at this time.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Light lake effect will set
up Tuesday but no deep moisture source. Better chance on
Wednesday as the synoptic moisture increases ahead of the next
front. High finally moves off the SE Coast, which will all next
cold front to push through on Thursday. Looks like a widespread
synoptic event, but system will push through so quickly do not
expect much in the way of accumulations.
&&
.LONG TERM /THURSDAY THROUGH SUNDAY/...
Below normal temperatures continue through the long term forecast.
ECMWF coming into agreement with GFS for next weekend. YDY the
ECMWF had low tracking across the Ohio Valley Saturday into Sunday.
Today both models have high pressure over the forecast area through
the entire weekend, with the low tracking much further south. So
next weekend should be cool, but dry with some sun.
&&
.AVIATION /00Z Monday THROUGH Friday/...
Showers with isolated thunderstorms accompanying a cold front
will move across NE Ohio/NW PA producing pockets of strong
winds in excess of 40 knots. These winds may impact YNG/ERI over
the next hour or two with the potential for stronger winds
decreasing beyond that time. Ceilings will lower behind the
front with most sites settling into the MVFR range overnight.
Southwest winds will be remain breezy overnight with gusts of
20-25 knots and a few scattered showers overnight. Otherwise
winds will shift to the northwest with the passage of a
secondary front during the day on Monday. Scattered showers will
mix with snow during the afternoon and eventually transition to
all snow by early Monday evening. Have included MVFR
visibilities with the mixed precip and snow but can not rule out
periods of IFR.
OUTLOOK...Non-VFR probable on Monday into Tuesday with snow as
a cold front crosses the region.
&&
.MARINE...
Currently Low near the Thumb of MI with strong cold front extending
SW to S of Kansas City. Models in good agreement tracking the Low
into New England Monday, with the trailing cold front pushing across
the Lake Monday morning. Surface winds will turn to the southwest
and increase to 15 to 25 knots tonight as a prefrontal trough swings
across the Lake, and 925 winds of 35 knots. Winds turn to the NW
behind the front and gradually diminish. Expect Small Craft
Advisory to last until Monday evening. After that high pressure
tracks across the Ohio Valley Wednesday, then moves off the SE coast
Thursday. That will allow another cold front to push across the
Lake on Thursday.
&&
.CLE WATCHES/WARNINGS/ADVISORIES...
OH...None.
PA...None.
MARINE...Small Craft Advisory until 10 PM EST Monday for LEZ145>149.
Small Craft Advisory until 10 AM EST Monday for LEZ144.
&&
$$
SYNOPSIS...Griffin
NEAR TERM...KEC/Griffin
SHORT TERM...DJB
LONG TERM...DJB
AVIATION...KEC
MARINE...DJB
Area Forecast Discussion
National Weather Service Grand Junction CO
705 PM MST Sun Dec 2 2018
.UPDATE...
Issued at 701 PM MST Sun Dec 2 2018
Persistent light snow continues over the central valleys of the
western slope. Reports of a few accidents on bridges and
overpasses has prompted the issuance of a Special Weather
Statement, covering the threats of refreezing surfaces and 1-3
inches of snow from now through midnight tonight. The statement
focuses on areas from Grand Junction eastward to Glenwood
Springs, however the higher terrain along Douglass pass, Rio
Blanco Hill, and the Grand Mesa will also be impacted. Satellite
and radar trends noted in the previous AFD update continue.
UPDATE Issued at 559 PM MST Sun Dec 2 2018
Radar and satellite trends as well as surface observations and
webcams indicate that snow is winding down over eastern Utah and
western Colorado this evening. Therefore, the Winter Weather
Advisory will be allowed to expire at 6pm.
Interestingly, light snow has persisted over the central valleys,
especially over Grand Junction and northward to Rifle along I-70.
What is left of the 700mb low pressure center currently sits over
far southern Mesa County, and some cooler cloud tops have
blossomed to the east of the low. These colder cloud tops are co-
located with an area of increasing radar returns. 0z radiosonde
data from GJT shows a particularly saturated portion of the
profile between 600 and 750mb, where temperatures are running
between -14 and -8C. Current thinking is that a slight amount of
lift on the east side of the decaying low, combined with
temperatures on the lower end of the dendritic growth zone, are
combining to maximize crystal production and snow rates over Mesa
and Garfield County. High res guidance has not picked up on these
trends very well, so we will have to carefully monitor radar and
satellite for Short Term forecast updates this evening. The
expectation is that this activity will diminish in about 2-3
hours as the low pressure falls apart. We`ll see...
&&
.SHORT TERM...(Tonight through Monday night)
Issued at 139 PM MST Sun Dec 2 2018
An energetic trough with support from a 140 kt jet rounding its
base and divergent flow aloft leading the way will continue to
lift slowly NE over western CO and eastern UT. Temperatures are
cold enough for snow to reach and accumulate in the lower valleys
through about 6 PM this evening. A Winter Weather Advisory
continues until that time for most of southwest CO. Both the HRRR
and HiRes models show support for precipitation decreasing this
evening and continuing to move thru central and northern CO and
UT. At sunrise Monday what`s left will be over the northwest CO
plateau and central CO mountains and valleys. Believe low stratus
and maybe some fog will hang in the central valleys through the
morning. Remnant orographic showers in the northern and central
mountains will slowly dissipate Monday night.
.LONG TERM...(Tuesday through Sunday)
Issued at 139 PM MST Sun Dec 2 2018
The long range will be characterized by progressive large
amplitude systems. Strong high pressure will move through the
Great Basin and Central Rockies Tue. through Wed., being built up
by a deep low pressure system developing off the southern CA
coast. The remnants of a weak warm front will produce a very
slight chance of showers Tuesday night and Wednesday morning.
On Thursday the low will begin moving onshore and it will
influence weather across all of the southwestern U.S., southern
Great Basin and Central Rockies. Plenty of moisture is expected to
be carried into the area from the SW. This system should focus on
southeast UT, southwest CO and the CO central and southwest
mountains until the trough passes overhead Friday night. If this
solution holds together, the mountains and foothills of southwest
CO should bare the brunt of the storm.
Strong high pressure will begin moving in Friday night and
Saturday morning. On Sunday a large ridge will build over the
western U.S. ahead of another deep low developing off the west.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 508 PM MST Sun Dec 2 2018
Low clouds and snow continue across much of the forecast area. For
the overnight hours, conditions will start improving for KDRO and
eventually KCNY. Other TAF sites will likely vary from VFR to IFR
under showers as they move through. Another concern will be fog
where the snow has ended. Cloud cover may inhibit formation so
will amend TAFs as needed. By 12Z, conditions will be worst along
the I-70 corridor so KRIL, KASE, and KEGE will likely see MVFR/IFR
conditions until 18Z, give or take. Southern areas will see FEW to
SCT skies while the rest of the area will continue to see BKN
ceilings.
&&
.GJT WATCHES/WARNINGS/ADVISORIES...
CO...None.
UT...None.
&&
$$
UPDATE...MAC
SHORT TERM...CC
LONG TERM...CC
AVIATION...TGR
Area Forecast Discussion
National Weather Service Lincoln IL
931 PM CST Sun Dec 2 2018
.UPDATE...
Issued at 920 PM CST Sun Dec 2 2018
Spotty rain showers will transition to snow showers from NW to SE
overnight. There appears to be a narrow corridor of enhanced
forcing for precipitation across our SW counties, especially after
snowfall begins. This looks to be a high PoP and low QPF
situation. Still, a dusting of light snow could occur across that
area through mid-morning, possibly creating some slippery spots
for the Monday morning commute. Gusty northwest winds could create
some reduced visibilities during snow showers. Clouds will help
keep low temps from dropping off too far from the mid-evening
readings, with around 30 toward Galesburg and the mid to upper 30s
S of I-70.
The shortwave will depart to the east Monday afternoon, taking
precip with it. However, advancing cold air will limit high
temperatures to climbing only a few degrees above morning lows.
Most areas will remain in the 30s for highs.
Update this evening was to mainly bump up the PoPs/snow wording
slightly overnight into Monday. The latest forecast info is
already available.
&&
.SHORT TERM...(This evening through Monday)
ISSUED AT 230 PM CST Sun Dec 2 2018
20z/2pm surface analysis shows a 994mb low centered over eastern
Michigan, with a trough axis extending W/SW across north-central
Illinois into northern Missouri. Widespread showers have developed
along the trough, particularly across the northern half of the
KILX CWA in advance of a well-defined upper low. As the upper
feature gradually passes to the east, colder thermal profiles on
its back side will allow the rain to transition to snow from west
to east across the area tonight. Minor snow accumulations of a
couple tenths of an inch are expected, mainly on grassy surfaces
as overnight lows drop into the lower to middle 30s. Light snow
will linger through Monday morning before coming to an end by
midday as the trough axis dissipates. Despite an end to the
precip, skies will remain overcast through the day. High
temperatures will hover in the 30s, while brisk northwesterly
winds create wind-chill readings in the teens and 20s.
.LONG TERM...(Monday night through Sunday)
ISSUED AT 230 PM CST Sun Dec 2 2018
Cloudy and cold weather will continue through Tuesday before the
sun finally returns by Wednesday as upper heights begin to rise in
advance of the next approaching short-wave trough. 12z Dec 2
models are in very good agreement with the track and timing of the
wave, showing the strongest lift and deepest moisture passing
through central Illinois late Wednesday into early Thursday. As a
result, will introduce chance PoPs for snow west of I-55 late
Wednesday night...then will go with high chance to likely PoPs
across the board Thursday morning. The atmosphere will be cold
enough to support mainly snow, with a transition to a rain/snow
mix or all rain along and south of a Champaign to Shelbyville line
by Tuesday afternoon as the precip begins to depart. Up to 1 inch
of snow is expected along/north of the I-72 corridor.
Once this system exits the region, cool/dry weather will prevail
through the remainder of the extended. Will need to keep an eye on
a southern stream system tracking across the Southern Plains on
Saturday into the Deep South by Monday. Previous models had
indicated precip from this feature may spread as far north as
parts of central Illinois late Saturday into Sunday: however, the
latest GFS and ECMWF now keep the precip much further south out
of Illinois. Will continue to feature low chance PoPs across the
far southern CWA over the weekend, but these will likely be
removed pending support from another model run. Main weather story
will be the continuation of below normal temps...as highs remain
in the 30s through next Sunday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 537 PM CST Sun Dec 2 2018
MVFR/IFR ceilings will persist at the central Illinois terminals
through the entire 00z TAF period. Latest radar imagery shows
widespread light showers from just east of the Illinois River to
the Indiana border. Based on radar loops and HRRR forecast, have
included predominant -RA at KBMI through 02z, KDEC through 03z,
and KCMI until 06z. After that, have maintained VCSH at all sites
until Monday afternoon. Ceilings will hover in the IFR to low MVFR
category through the night, then will gradually improve into the
MVFR category from west to east across the area on Monday.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...Shimon
SHORT TERM...Barnes
LONG TERM...Barnes
AVIATION...Barnes
Area Forecast Discussion...UPDATED
National Weather Service North Platte NE
530 PM CST Sun Dec 2 2018
.SYNOPSIS...
Issued at 310 PM CST Sun Dec 2 2018
H5 analysis from this morning had a broad trough of low
pressure across most of the CONUS. Closed low pressure was noted
over southeastern Iowa with a shortwave trough extending to the west
northwest into eastern Wyoming. Weak high pressure was noted over
eastern Saskatchewan with another strong shortwave noted over
southern Utah and other embedded shortwaves extending from this
feature into western Nevada and northern California. Further east of
this large trough, a low amplitude ridge extended from the western
Atlantic into the Canadian Maritimes, while west of this trough,
another ridge extended from the eastern Pacific north into the Gulf
of Alaska and the Yukon. At the surface, low pressure was noted over
southeastern Michigan with a cold front extending south to the
Florida Panhandle. West of the low, an occluded front extended to
the west into northern Illinois. High pressure was located over
western Manitoba and northerly winds were present from eastern North
Dakota into central and eastern Nebraska. Lighter winds were present
across the Nebraska Panhandle this afternoon. Light snow continued
to fall across portions of southwestern and Central Nebraska as of
early afternoon. Accumulations with this were very light with hourly
amounts of one to two tenths of an inch per hour. As of 3 PM CST,
snow was present over southern Custer, eastern Lincoln and portions
of eastern Frontier county. This activity is expected to push out of
the area over the next 1 to 2 hours so the winter headlines will be
cancelled with the 4 PM CST forecast issuance.
&&
.SHORT TERM...(This evening through Monday)
Issued at 310 PM CST Sun Dec 2 2018
Light snow will come to an end across
southeastern forecast area by mid evening as forcing finally tracks
east and southeast into sern Nebraska and northern Kansas. Only a
dusting of additional accumulation will be possible and with winds
expected to diminish by sundown, do not see headlines being extended
into the evening. Otherwise, the models continue to advertise plenty
of low level moisture overnight which will be favorable for clouds.
That being said, lows tonight should be higher than the latest
guidance which has lower teens and even some single digits in the
northwest. Given the expected cloud cover, have opted for warmer
than guidance lows tonight and didn`t deviate much from the
inherited forecast. Looking at the latest NAM12 solution from this
morning, light winds and a saturated boundary layer are depicted in
this model tonight in the northwestern forecast area, which would be
favorable for fog formation. The latest HRRR and NAM nest solutions
lend support to fog in the northwest as well. That being said, will
insert mention of patchy fog in the northwest tonight. High pressure
will build south into eastern Nebraska on Monday. However, abundant
low level moisture will persist across the forecast area on Monday,
leading to cloudy to mostly cloudy skies for Monday. This will
limit highs to the lower to middle 20s.
.LONG TERM...(Monday night through Sunday)
Issued at 310 PM CST Sun Dec 2 2018
Surface high pressure
will drop south into the Ozarks Monday night shifting the winds to
the west across the forecast area. This will dry out the boundary
layer, however, mid and high level clouds will stream in from the
northwest ahead of another approaching disturbance. Temperatures
will be cool once again with highs struggling to reach the freezing
mark. A stronger, upper level trough and arctic front will track
into the northern plains early on Wednesday. Ahead of the front,
warmer air will push into the forecast area from the west and
southwest allowing highs to reach the middle to upper 30s. The
warmup will be temporary though as the arctic front arrives on
Wednesday evening. Not expecting much in the way of precipitation
with the front as the best mid level forcing is east and southeast
of the forecast area. For the remainder of the work week into
Saturday, the forecast area will be well north of the arctic front.
Highs will be in the lower 20s for Thursday and mid to upper 20s for
Friday. By Saturday, highs will reach the upper 20s to lower 30s.
The next chance for possible precipitation may move into southern
Nebraska for Friday into Saturday. A nice southern stream trough of
low pressure, will slide from the desert southwest into the southern
plains and southeastern CONUS. The latest ECMWF and GFS solutions
keep the best forcing with this system well south of the area. With
that in mind, will continue with a dry forecast and warm highs into
the 30s for next Sunday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 529 PM CST Sun Dec 2 2018
LIFR in fog is expected across Sheridan and Cherry counties
tonight. Elsewhere across wrn and ncntl Nebraska, IFR/MVFR cigs
continue overnight. An area of VFR is underway across parts of wrn
Nebraska. This area of partial clearing is expected to remain
stationary overnight.
Flight conditions are expected to improve to VFR/MVFR from west to
east Monday.
&&
.LBF WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
SYNOPSIS...Buttler
SHORT TERM...Buttler
LONG TERM...Buttler
AVIATION...CDC
Area Forecast Discussion
National Weather Service Marquette MI
600 PM EST Sun Dec 2 2018
.SHORT TERM...(This evening through Monday)
Issued at 421 PM EST SUN DEC 2 2018
WV imagery and RAP analysis indicated a mid/upper level trough from
James Bay to the mid Mississippi Valley with a prominent shortwave
over northeast IL. Radars indicated diminishing snow over most of
Upper Michigan as the supporting 800-600mb fgen/deformation weakens
and slides to the south and east. However, the combination of
lingering 850-600mb moisture, strong nne flow across Lake Superior
and orographic lift into north central Upper Michigan has sustained
moderate to heavy snow, despite 850 mb temps only around -6C.
Snowfall totals around the NWS office. Closer to the shore totals
were only a few inches at most. Over the west, the nne flow has also
brought an increase in snowfall rates to KIWD.
Tonight, Although CAA will bring slightly colder air into the region
with 850 mb temps to around -10C to -12C, inversion heights near
KMQT dropping to 6k ft by 06z and near 4k ft by 12z, along with 925
mb winds dropping to 25 knots will bring an end to the heavier lake
and terrain enhanced snow. Since a couple more inches are expected
at KIWD and up to 4-5 inches near KMQT, an advisory was issued for
this evening for Gogebic county and the warning remains in effect
for Marquette county. Otherwise, with weak synoptic forcing over the
area additional accumulations over the rest of the area are
expected to remain less than a half inch.
Monday, Winds will diminish and back with increasingly anticyclonic
flow. So, any remained snow will also diminish with some minor
additional accumulations of less than an inch in the morning.
Otherwise, temps will remain near seasonal averages with highs in
the upper 20s to around 30.
.LONG TERM...(Monday night through Sunday)
Issued at 310 PM EST SUN DEC 2 2018
Shortwave finally departs the Great Lakes region, with weak ridging
sliding east towards the Western Great Lakes for late Mon ngt. This
should provide some drier air in the lower/mid-levels, bringing a
brief break to any precipitation for the Upper Peninsula. Thermal
trough will remain overhead, which will keep any precip in mainly
dendritic or snow form. But as mentioned earlier, precip chances are
going to be minimal for a brief period.
Later Tue yet another weak mid-level trough will approach from the
west, which will re-introduce some precip chances for the Upper
Peninsula into Wed, and return a northwest flow with Lake Effect
setup in the main snowbelts for later in the extended. Wed ngt
guidance currently anticipates a stronger frontal boundary will
arrive from the northwest, which will push high temps down further
for Thur only reaching the teens to lower 20s Thur into Fri.
Towards the end of the current extended periods guidance continues
to hint that a shift in the pattern will start, with more of a quasi-
zonal or west to east orientation. This pattern would suggest a
trend towards drier setup and possibly a warming trend currently
just beyond the extended.
&&
.AVIATION...(For the 00Z TAFS through 00Z Monday evening)
Issued at 600 PM EST SUN DEC 2 2018
MVFR conditions will remain for the forecast period at CMX. For SAW,
VLIFR/LIFR conditions will be the prevailing conditions this evening
with persistent lake enhanced/effect snow and blowing snow
contributing to low visibilities with gusty winds. There will be
some improvement to MVFR after midnight as the slightly drier air
moves in at SAW. IWD will briefly be low MVFR Mon morning, otherwise
will stay IFR.
&&
.MARINE...(For the 4 PM Lake Superior forecast issuance)
Issued at 421 PM EST SUN DEC 2 2018
As the pressure gradient weakens tonight winds will diminish to less
than 30 kts late tonight and to less than 25 kts on Monday while
gradually backing to the northwest. Later Monday afternoon through
the middle of the week, winds will rotate back and forth between
west and northwest at speeds of 15 to 25 knots. Next chance for
stronger winds arrive on Thursday behind a stronger cold front.
&&
.MQT WATCHES/WARNINGS/ADVISORIES...
Upper Michigan...
Winter Weather Advisory until 11 PM CST this evening for MIZ009.
Lakeshore Flood Advisory until 7 PM EST /6 PM CST/ this evening
for MIZ002-009.
Winter Storm Warning until midnight EST tonight for MIZ004-005.
Lakeshore Flood Advisory until 2 AM CST Monday for MIZ012.
Lake Superior...
Gale Warning until 2 AM EST Monday for LSZ248>251-265>267.
Gale Warning until 1 AM EST Monday for LSZ243>245-264.
Gale Warning until 11 PM EST this evening for LSZ246-247.
Gale Warning until midnight EST /11 PM CST/ tonight for LSZ162-
240>242-263.
Lake Michigan...
Gale Warning until 5 AM EST Monday for LMZ221-250.
&&
$$
SHORT TERM...JLB
LONG TERM...Beachler
AVIATION...07
MARINE...JLB
Area Forecast Discussion
National Weather Service Mount Holly NJ
930 PM EST Sun Dec 2 2018
.SYNOPSIS...
Low pressure will move from the Great Lakes Region this evening
down the Saint Lawrence Valley Monday. The associated cold
front is expected to sweep through our region late tonight and
Monday. High pressure will build in for much of the middle part
of the week, although a few weak disturbances will also cross
the area. A cold front will cross the area next Friday, followed
by high pressure moving in for the beginning of next weekend.
The next low pressure system may lift along the coast early next
week.
&&
.NEAR TERM /THROUGH MONDAY/...
930pm update: added Carbon/Monroe Counties to the Dense Fog
Advisory as visibilities continue to trend downward as of this
hour. Held off on an advisory in southern New Jersey and
central/southern Delaware since visibilities remain above
advisory criteria in these areas. Thinking areas south of the
front, excluding marine zones, should maintain this trend.
Showery activity also appears to have a downward trend as well,
however may still see some showers firing along the frontal
boundary that is stalled across the Delaware River Valley for
the next few hours. Areas of light drizzle will also be possible
until the arrival of the cold front later on tonight.
Low temps south of the warm front might be a bit too cool, but
most hi-res guidance indicates temps will begin falling later on
tonight despite temps failing to fall much this evening.
Previous discussion...
Another question mark is the potential for some convective
showers to develop along the southwest-northeast oriented front
this evening. Both the HRRR and NAM Nest indicate this, mainly
southeast of the Interstate 95/295 corridor through midnight.
Indeed, a fairly strong temperature gradient exists here, as
Kent/Sussex Counties in Delaware have warmed considerably (where
greater mixing has developed). The associated stronger
southwest winds have also led to modest convergence along this
boundary, and with the approach of a strong vort max to our
north/west this evening, sufficient large-scale lift should be
in place to generate some showers. Although not completely out
of the question, the thunder potential appears too low for
mention at this point. Have increased PoPs in central/southern
NJ and Delmarva to depict this threat.
The cold front associated with the vort max and attendant
surface low to the west-northwest begins to move through during
the overnight hours, and this should advect drier air into the
region as winds switch to westerly. This will be the end of the
fog/low clouds across the area.
Temperatures will remain fairly steady through the night, but
will drop somewhat after the cold front moves through late.
For Monday, as the surface low to our northwest lifts northeast
along the Saint Lawrence River, west flow will become
established in the northern Mid-Atlantic. Associated cold
advection will counter the warming effects of downsloping and
boundary-layer mixing. Skies will be partly to mostly sunny for
most of the area (at least until the deeper mixing occurs during
the afternoon, which may aid in the development of
stratocumulus, especially in the northwestern CWA). The
competing meteorological effects will mean high temperatures
fairly similar to those seen today, except for central/southern
Delmarva, where it will be decidedly cooler (by about 7-12
degrees).
The main sensible-weather impact on Monday will be breezy
winds, which may gust 25 to 35 mph during the day. Increased the
wind forecast substantially given latest BUFKIT soundings and
statistical guidance.
&&
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
A rather quiet period is in store as a broad surface high
slowly moves into the Southeast. The main question is what
impacts a strong vort max moving through the central/southern
Mid-Atlantic may have on our area Tuesday night and Wednesday.
Model consensus seems to suggest showery precipitation will stay
predominantly south of the area, though I cannot completely
rule out a few in our southern areas. However, given the light
look to the precip, short time window, and fairly strong
consensus of the best lift being south of the area, kept PoPs
non-mentionable through the period.
Conditions may remain somewhat breezy on Tuesday as the
pressure gradient does not completely relax given the building
high pressure to our west/southwest and the retreating low in
the Canadian Maritimes. Temperatures will be below seasonal
averages, by around 6- 12 degrees, both Tuesday and Wednesday,
with Wednesday being a little colder as warming effects from
mixing/downsloping diminish. It may also be cloudier on
Wednesday (than currently forecast) if the effects from the
aforementioned vort max are greater than currently projected.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
A long wave mid level trough is forecast to settle over the
eastern states for the period from Wednesday night through
Friday. An initial short wave is expected to be located over our
region on Wednesday evening. It should quickly move away to our
east on Wednesday night. A second short wave and an
accompanying surface cold front are anticipated to arrive on
Thursday night. We will mention a low or slight chance of snow
showers on Thursday night from around the Interstate 78 Corridor
northward, otherwise it should be cold and dry from Wednesday
night into Friday.
The mid level long wave trough is expected to lift to our
northeast on Saturday with a split flow becoming established
over the Middle Atlantic states and vicinity for Sunday. Cold
air to the north and moisture building up from the south should
result in some wintry precipitation. Presently, the guidance is
suggesting the the resulting surface low will be along the
Southeast coast on Sunday with the precipitation remaining to
our south at that time. However, it is expected to begin
progressing up the coast for Monday the 10th and it is
definitely a system to monitor in our region for the beginning
of next week.
&&
.AVIATION /02Z MONDAY THROUGH FRIDAY/...
The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY and surrounding areas.
Tonight...Generally IFR/LIFR through about 09Z to 11Z when a
cold front is expected to begin scouring out the low level
moisture. There is a chance of showers until 03Z mainly around
KMIV and KACY. Southwest wind 8 knots or less becoming west
around 10 knots after 09Z.
Monday...Mainly VFR. Scattered clouds in the morning with a
deck of stratocumulus expected in the afternoon (bases 4000 to
5000 feet). Westerly wind 10 to 15 knots with gusts of 20 to 25
knots.
Outlook...
Monday night through Wednesday...Predominantly VFR with breezy
west to northwest winds Tuesday (10 to 15 kts with higher gusts)
and lighter winds on Wednesday (5 to 15 kts). However, a nearby
storm on Wednesday lends to some uncertainty regarding the sky
conditions and winds in our area. High confidence Tuesday; low
confidence Wednesday.
Wednesday night...Mainly VFR. Northwest wind 5 to 10 knots.
Thursday...Mainly VFR. West to southwest wind 5 to 10 knots.
Thursday night...Mainly VFR. Southwest wind 5 to 10 knots
becoming northwest.
Friday...Mainly VFR. Northwest wind 10 to 15 knots.
&&
.MARINE...
Dense fog continues on the Atlantic coastal waters and Delaware
Bay. Extended dense fog advisory through the night, with
improvement expected thereafter thanks to a cold-frontal
passage.
Winds on the waters have been sub-advisory today, but seas are
elevated. This should generally hold through tonight, but as a
cold front moves through, directions will turn westerly and
gusts will increase to 25 to 30 kts on Monday. Small craft
advisory is in effect for the Atlantic waters through Monday.
Sub-advisory conditions should occur on Delaware Bay.
There is a chance of showers this evening, and a rogue
lightning strike cannot be ruled out. Winds/waves may become
erratic near any showers that develop.
Outlook...
Monday night...Lingering advisory-level northwest winds on the
Atlantic waters through much of the night. Small craft advisory
was extended through the night.
Tuesday and Wednesday...Sub-advisory winds/seas. Fair on
Tuesday, but showers cannot be ruled out on Wednesday,
especially in the southern portions of the Atlantic waters.
Wednesday night and Thursday...No marine headlines are
anticipated.
Thursday night and Friday...A northwest wind may gust to 25 or
30 knots.
&&
.PHI WATCHES/WARNINGS/ADVISORIES...
PA...Dense Fog Advisory until 4 AM EST Monday for PAZ054-055-
060>062-070-071-101>106.
NJ...Dense Fog Advisory until 4 AM EST Monday for NJZ001-007>010-
012>015.
DE...Dense Fog Advisory until 4 AM EST Monday for DEZ001.
MD...Dense Fog Advisory until 4 AM EST Monday for MDZ008.
MARINE...Dense Fog Advisory until 6 AM EST Monday for ANZ430-431-
450>453.
Small Craft Advisory until 6 AM EST Tuesday for ANZ450>455.
&&
$$
Synopsis...CMS/Fitzsimmons/Johnson
Near Term...CMS/Staarmann
Short Term...CMS
Long Term...Iovino
Aviation...CMS/Iovino
Marine...CMS/Iovino
Area Forecast Discussion
National Weather Service Pocatello ID
730 PM MST Sun Dec 2 2018
.SHORT TERM...Tonight through Wednesday. A second update this
evening as the latest 00z NAM12 and HRRR are indicating widespread
light snowfall continuing across the SE mountains including Cold
Water to Pocatello to Shelley overnight. Have boosted precipitation
potential and snow accumulations as a result. Totals still remain
below advisory levels. See previous discussion below for additional
information. Huston
Persistent snow lingers along and south of Interstate 86. Snowfall
intensity is pretty light given the lack of upper-level dynamic
support. However, surface convergence and upslope flow should
sustain this area of now through tomorrow. A weak upper trough will
swing through tonight, lifting the area of snow northeastward into
the Driggs and Island Park areas, and as far south as Bear Lake.
Snow in the Central Mountains tomorrow will continue due to
orographic lift, though intensity will remain light for most areas.
Mountain passes will see about 1 to 3 additional inches of snow
through tomorrow afternoon. Monday and Tuesday will see the upper
low moving out of the area while another upper low approaches from
the California coast. Models are keeping precip right along our
southern border Tuesday night and Wednesday. NAM lifts the precip a
little further northward, but doesn`t progress it much further
northward than the I-86 corridor. Hinsberger
.LONG TERM...Wednesday night through Sunday. Complex forecast
continues to remain on tap for the beginning of the extended portion
of the forecast, as SE Idaho remains sandwiched between stout NW
flow and embedded disturbances flowing east of the Divide, and a
broad low centered over California. Ejecting out of this low will be
a lead disturbance and its associated band of light snowfall, whose
evolution is still looking difficult to pin down. The question that
remains is...how much Snow will make it into Idaho from the south?
Recent trends continue to suggest a southerly adjustment to the
forecast is needed -- and have followed that trend. We`re now
carrying light Snow chances late Tue-Thu for those areas adjacent to
the Utah border, including Malad, Preston and Bear Lake. Recent
trends suggest we may need to narrow the timing as well, as it now
appears Wednesday will see the highest probability of seeing
Precipitation. Overall amounts appear to be on the light side.
After this disturbance moves away, a ridge of high pressure is then
forecast to gradually build over the region from late Thursday
through next weekend. The drying trend that began to emerge on
yesterday`s guidance for next weekend continues, and am now carrying
dry conditions most areas (except for a sneaky snow shower or two
around Island Park) through next weekend. As a result of the high
pressure in place across our region, the sprawling and moist Pacific
trough that moves ashore early Sunday is forced to make only slow
eastward progress, and latest indications suggest any Precipitation
associated with this system will hold off until next Monday, mainly
over the Central Mountains.
Continuing to forecast seasonably cold Temperatures through the week,
with Temperatures 10-15 degrees below climatology for this time of
year. This means sub-freezing highs and numerous single digit lows
for the Snake Plain, with below zero lows for high elevation
valleys. Cloud cover near the Utah border should keep lows `warmer`
there until that cloudiness moves out late-week. We`ll begin to see
a warming trend develop next weekend, which will be most pronounced
above the inversions at mid and upper slopes. We`ll likely need to
wait until early next week for any pronounced warming in valleys
with the approach of the next trough. As a result of the inversions,
patchy fog will be possible in valleys along with deteriorating air
quality through the week. AD/Hinsberger
&&
.AVIATION...Low confidence TAF forecast continues. Broad cyclonic
flow remains in place over the region, with weak surface convergence
aiding to focus snow showers in a north-south oriented band from SUN
south to between BYI and PIH. Have seen conditions improve at BYI to
MVFR, and most guidance suggests this condition will persist into
Monday morning. However, there is extensive IFR stratus in place to
the west across the Magic and Treasure valleys, and the westerly
flow may allow this to advect into the terminal overnight. For PIH,
the MVFR stratus and associated light Snow shower activity has
arrived ahead of schedule, and MVFR to occasionally IFR CIGS
expected to persist into Monday morning with occasional SHSN. With
the southwest flow forecast to overspread the Snake Plain, high
resolution guidance allows this stratus deck to move into IDA
between 06 and 09Z, and begin to rapidly drop CIGs at this point.
Will need to continue to monitor this progression. May see some of
this move into DIJ as well, but am carrying the most optimistic
conditions here. For SUN, MVFR CIGs in place now, and may see these
drop to airfield minimums late this afternoon through early evening
as reservoir of stratus and SHSN may advect in from the south. Should
see some improvement in conditions here late-night but again
confidence is quite low on the details and future amendments will
likely be needed. AD/Hinsberger
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Area Forecast Discussion
National Weather Service Tulsa OK
803 PM CST Sun Dec 2 2018
.UPDATE...
Main update was to insert some low PoPs down near the Red River
after midnight tonight. See discussion below.
&&
.DISCUSSION...
As discussed earlier, an approaching upper wave, which is also
increasing clouds this evening over the region, will also help to
enduce frontogenesis in the 850-600MB layer tonight, mainly
along/near the Red River valley. The latest runs of the HRRR
suggest that some light rain could develop as far east as southern
Choctaw county, and have thus raised PoPs to slight chance.
Otherwise, no other changes needed as trends in other data look
good. Surface high pressure is building quickly southward out of
central Canada and down the Plains, and this will bring a
reinforcing push of colder air into the region. An even colder day
is forecast on Monday.
Lacy
&&
.PREV DISCUSSION... /Issued 550 PM CST Sun Dec 2 2018/
AVIATION...
CONCERNING TAF SITES KTUL/KRVS/KBVO/KMLC/KXNA/KFYV/KFSM/KROG.
VFR ceilings will continue to threaten KBVO and far northern AR
TAF sites this evening as mid level clouds advance from the west
ahead of next system over northern NM. Dry low levels should keep
VFR conditions in place at KMLC and KFSM through the period.
Reinforcing cold surge associated with secondary northern stream
system however will bring MVFR ceilings to northern OK and AR
terminals after midnight. With system slow to eject expect low
clouds to remain in place much of the day Monday. Generally light
northwest winds expected overnight with speeds closer to 10kt
during the day Monday.
PREV DISCUSSION... /Issued 315 PM CST Sun Dec 2 2018/
DISCUSSION...
The main forecast concerns center on a storm system that will
affect the region late this week into next weekend. Heavy rainfall
and winter weather potential will accompany this system. A
challenging forecast lies ahead in the days to come. I will touch
on this later.
Models for several days have suggested that a band of very light
precip will spread east along/near the Red River valley late
tonight. This appears to be forced by 850-600 mb cold
frontogenesis, as a lobe of PV slides across the Plains at the
base of the broad and deep upper trough over the CONUS. However,
models show a fairly dry sub-cloud layer with only light precip
falling into this layer. Also, the forcing weakens and shifts
southeast by the time this precip would extend into SE OK. As a
result, I`m going to maintain a dry forecast for the Red River
valley region for tonight. Reinforcing push of colder air arrives
tonight as surface high pressure over central Canada slides south
down the Plains in the wake of the departing storm system. High
temps Monday will be a good 10 degrees colder than today.
Now to the meat of this forecast. A split flow pattern currently
exists over the eastern Pacific to the west of the broad CONUS
upper trough. As this blocking pattern breaks down by the middle
of this week, a strong system in the southern stream will move
into southern CA Thursday and then quickly east across the
southern tier of states thru next weekend. The system will tap
plentiful Gulf moisture to the south and will produce a fairly
significant precip event over the south central states Friday into
Saturday. In fact, more than an inch of precip is forecast over
the ArkLaTex, SE OK and WC AR. So part 1, the moisture, is a
given. It will precip.
Now to part 2, thermal structure of the environment when this
precip is falling. This will be by far the most challenging part
of the forecast, as it usually is in complex winter weather
scenarios. The GFS has trended colder and closer to the ECMWF, and
will use a blend of the thermal profiles for this forecast. As
such, the transition zone between liquid and frozen precip will
dissect the forecast area, with obviously rain in the south and a
mixed bag of winter types to the north. It is worth noting that there
are differences in the northward extent of the warm layer between
the GFS and ECMWF. Given that the event is still several days out,
a blend is the better approach for now. Since the ECMWF handles
low level cold air better typically, I leaned more heavily on the
raw surface temps for this forecast. The end result and main point
remain the same. The potential for a significant winter weather
event across a good chunk of the area remains. The details of
which will continue to be refined in the coming days.
Lacy
&&
.PRELIMINARY POINT TEMPS/POPS...
TUL 29 40 23 42 / 0 0 0 0
FSM 33 45 27 44 / 0 0 0 0
MLC 33 44 25 44 / 0 10 0 0
BVO 29 39 21 40 / 0 0 0 0
FYV 29 38 21 38 / 0 0 0 0
BYV 30 38 23 36 / 0 0 0 0
MKO 32 42 24 42 / 0 0 0 0
MIO 28 38 22 38 / 0 0 0 0
F10 30 42 23 43 / 0 10 0 0
HHW 37 49 27 47 / 10 10 0 0
&&
.TSA WATCHES/WARNINGS/ADVISORIES...
OK...None.
AR...None.
&&
$$
LONG TERM....30