Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/18/20
Area Forecast Discussion
National Weather Service La Crosse WI
831 PM CST Mon Feb 17 2020
.UPDATE...
Issued at 825 PM CST Mon Feb 17 2020
Extended the advisory west of the Mississippi River out to
midnight as the snow is exiting the area slower than previously
expected. With a couple more hours of moderate snow, with
visibilities down to a mile or less, roads will remain snow
covered and slippery. Additional accumulations for the rest of the
evening should be in the 1 to 2 inch range for most locations. If
trends in the HRRR are correct, the snow should begin to taper off
in the western sections between 10 pm and midnight and in the east
after midnight. For now, didn`t extend the eastern sections as the
HRRR has been showing the a diminishing trend after midnight as
well.
&&
.SHORT TERM...(Tonight)
Issued at 150 PM CST Mon Feb 17 2020
A challenging forecast persists heading through this evening. Some
amplification of an approaching mid-level shortwave trough is
expected as in interacts with another shortwave approaching from
the northern plains. The trend has been for a slowing of the
onset of accumulating precip in the high res models, especially to
the north and east. Model guidance has struggled with the initial
snow across northeast IA/southwest WI with reports so far of a few
inches already. Accordingly, have added Grant County into the
Winter Weather Advisory. Still may see a transition to a mix/rain
for far southern areas as warmer air tries to lift north.
In addition, a several hour window of potentially moderate/heavy
snow is still expected this afternoon/early evening as the
additional snow develops from the west. In this swath, 2-5+ inches
of snow with rates exceeding 1 in/hr are possible, currently
favoring near or just south of the MN/IA border area into central
WI. The 17.12Z HREF suggests a period of at least 1 in/hr rates
across far northeast IA from around 3-7 pm, spreading into
southwest/central WI in the 6-10 pm window. Given the marginal
thermal profiles, rain could mix in at times under lighter rates
or where temps are a bit warmer, such as river valleys. By late
evening, precip should wind down as the weak surface low pulls
into the northern Great Lakes.
.LONG TERM...(Tuesday through Monday)
Issued at 150 PM CST Mon Feb 17 2020
Beyond the early week system, a quiet week weather-wise is ahead,
with temps the primary challenge. Tuesday will be noticeably cooler
and breezy with highs in the teens/20s. The strongest surge of low
level cold advection will arrive Tuesday afternoon as a secondary
upper trough skirts the northern Great Lakes. Some clearing is
expected through the day as a strong surface high begins to build in
from the Canadian prairies, although could see a period of stratus
and perhaps some flurries Tuesday afternoon/evening before
drying/clearing take place from the northwest. Temps will fall below
zero over much of the area Tuesday night, with the core of the cold
airmass situated across the area on Wednesday as 850 mb temps
descend into the -15 to -18C range. Highs will be mainly in the
single digits/teens. With the ridge axis sitting just to the west,
Wednesday night will be the coldest night of this short-lived cold
spell, with lows well below zero for most areas.
The surface high center will cross the area on Thursday. Limited
mixing and a cold start will keep highs in the teens to near 20,
despite slowly moderating low-level thermal fields.
Much milder Pacific air will spread into the Midwest late this week
into early next week as the upper air pattern flattens and the the
surface ridge slides east. Highs by the weekend will be back into
the 30s to perhaps 40s for some. General indications are that an
upper trough will eject from the southern plains Sunday with a
longwave trough deepening over the Rockies by early next week, but
confidence in the details of this evolution and precip chances from
late weekend and beyond is low right now.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 509 PM CST Mon Feb 17 2020
Surface analysis late this afternoon shows an area of low pressure
over northwest Missouri with a inverted trough of low pressure
extending north into northwest Wisconsin. Snow was occurring in
the vicinity of the inverted trough with IFR visibilities. Expect
that this snow will continue for a good share of the evening at
both airports until the short wave trough over South Dakota swings
across the region. Once the snow ends, the visibility should
rapidly increase but with ceilings remaining IFR/MVFR overnight.
VFR conditions should develop Tuesday morning as an area of high
pressure builds in from the northwest allowing the clouds to
scatter out.
&&
.ARX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory until midnight CST tonight for WIZ029-
032>034-041>044-053>055-061.
MN...Winter Weather Advisory until midnight CST tonight for MNZ079-
086>088-094>096.
IA...Winter Weather Advisory until midnight CST tonight for
IAZ008>011-018-019-029-030.
&&
$$
UPDATE...04
SHORT TERM...JM
LONG TERM...JM
AVIATION...04
Area Forecast Discussion
National Weather Service Columbia SC
727 PM EST Mon Feb 17 2020
.SYNOPSIS...
A series of upper disturbances and a frontal boundary will
bring rain to our forecast area Tuesday through Thursday. Drier
and cooler air will settle into our region Friday and Saturday.
Moderating temperatures expected Sunday and Monday with rain
moving back into the picture by Monday.
&&
.NEAR TERM /THROUGH TUESDAY/...
The upper level flow begin to turn back towards the southwest
in response to upstream troughing over the southern Rockies.
This will begin pushing moisture, along with a surface warm
front, back towards the north through the night. Much of the
night still should remain dry, with rain chances increasing
towards Tuesday morning from west to east. Clouds will be on the
increase this evening, and are expected to lower as the warm
front nears from the south. Expect patchy to potentially more
widespread fog to develop late tonight although latest HRRR
suggest bulk of fog back in central /north GA into the Upstate.
The cloud cover should limit radiational cooling, keeping lows
in the upper 40s northern Midlands to lower 50s in the CSRA.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/...
Tuesday and Tuesday night...Warm front will be north of the
forecast area Tuesday morning with with the first of a series of
impulses bringing rain to the area by mid morning. Model
sounding indicate a relatively stable air mass through the day
however with southwesterly flow pushing Gulf moisture into the
area and corresponding pwat values between 1.4 and 1.5 inches
through the day expect rain to continue. Cold front will
approach the forecast area Tuesday night and although
instability remains weak expect showers to continue as the front
begins crossing the area during the early morning hours.
Temperatures will range from the low 60s in the northern and
western Midlands to the upper 60s in the eastern Midlands and
southern CSRA. Lows will be in the low 50s along the NC Border
with upper 50s in the southern Midlands and CSRA.
Wednesday and Wednesday night...Cold front will drift just south
of the forecast area through the day Wednesday and be just south
of the area Wednesday night. Rain chances will remain high
through the day Wednesday then begin diminishing through the
late afternoon as the front moves south of the area. With the
weak forcing expect rain to continue through the day however
heavy rain is not expected. Temperatures are a concern as
northerly flow could keep temperatures lower depending on timing
of the front. Wednesday night the front stalls south of the
area and models continue having differences on how far south of
the area the front stalls. Expect the front to stall just south
of the area which will keep chance pops over the southern half
of the area with slight chance for the northern Midlands and Pee
Dee. Temperatures will be in the mid 50s to low 60s for highs
with low 40s for lows.
&&
.LONG TERM /THURSDAY THROUGH MONDAY/...
Frontal boundary will once again return northward on Thursday
before pushing offshore Thursday night as low pressure deepens
and moves away from the region. This will allow high pressure
along with cooler and drier air to build into the region for
Friday into Sunday. The next low pressure system will move into
the central US on Sunday and with the high pushing offshore
southerly flow will again begin pushing moisture into the area.
Rain chances will return for Sunday night and Monday as a warm
front crosses the region. Temperatures through the long term
will be below normal for Thursday through Saturday with near
normal for Sunday and Monday.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
IFR restrictions expected to develop overnight and continue
into Tuesday.
Moisture will deepen overnight with a warm front lifting into
the area. A cold front will approach the area on Tuesday and
cross the area Tuesday night. Rain will overspread the
terminals Tuesday morning and will continue into Tuesday night.
MVFR ceilings are already in place at AGS/DNL/OGB this evening
and should also develop at CAE/CUB. Deterioration to IFR/LIFR
is expected overnight as moisture deepens and will continue
throughout the day Tuesday. As the warm front moves northward
overnight, visibilities may also drop to IFR. Light easterly
winds will gradually veer to southwesterly by Tuesday evening.
EXTENDED AVIATION OUTLOOK...Showers and expected restrictions
Tuesday night through Thursday.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service Charleston SC
907 PM EST Mon Feb 17 2020
.SYNOPSIS...
High pressure will give way to a warm front lifting north
through the area Tuesday before a cold front pushes through on
Wednesday. Colder high pressure will then build in from the
north through the end of the week as low pressure passes
offshore Thursday into Friday. Warmer and eventually wetter
conditions are expected early next week.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
As of 9 PM: Based on latest runs of the CAMs, I will lower PoPs
to SCHC across the forecast area for tonight. Otherwise,
conditions still appear on track for areas to patchy fog to
develop late tonight.
As of 635 PM: I will update the forecast to increase sky cover
through tonight. The mention of fog developing later tonight
still looks good. However, based on latest guidance, I will
limit QPF to around 0.01 of an inch for tonight.
Previous Discussion:
Tonight: Within the prevailing west-southwest flow aloft,
embedded shortwave energy will spread across the forecast area
late tonight. At the surface, inland high pressure will steadily
dissipate as a weak low develops offshore under the influence
of the shortwave energy aloft. Overall, much of the overnight
will be dry. Late tonight, the forecast becomes challenging as a
subtle warm front lifts northward and into southeast Georgia.
There is considerable model disagreement regarding the
development of showers along and near the front. The GFS and
ECMWF depict good coverage of rain showers by day break Tuesday.
On the other hand, the NAM, HRRR, and RAP are all totally dry
and favor areas much further inland. These drier solutions seem
to be hitting on where the best low level convergence sets up,
which makes sense given the subtle nature of the warm front
lifting through the forecast area. Confidence is low and either
scenario is plausible, but the forecast has been trended in a
drier direction with lower rain chances. By sunrise Tuesday, the
forecast now shows 30-40 percent chances well inland, tapering
to 20 percent or less along and south of I-16. Fog is also a
concern with the presence of good low level moisture, light
winds, and the nearby weak front. Model guidance is mixed, but
tends to favor southeast Georgia for the best fog chances. The
forecast features areas of fog generally along and south of the
Savannah River, with just patchy fog further north. Can`t rule
out at least patchy dense fog, so we will maintain the mention
in the Hazardous Weather Outlook. Lows are forecast to bottom
out in the low 50s for most areas.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
Low to moderate confidence during this unsettled period. Shower
chances will increase on Tuesday as a warm front moves north
through the area, especially near the CSRA/Midlands/Pee Dee
closer to the deeper moisture/upper level energy. A cold front
will then move into the area late Tuesday night and push through
Wednesday. High pressure will then build in from the north into
Thursday as low pressure develops off the northern
Florida/Georgia coasts Thursday. The combination of deep
moisture and upper level energy will keep conditions unsettled
through the period with most places likely to see an inch or
more of rain, possibly even 2 to 3 inches in spots, although the
risk for significant flash flooding is low. Can`t rule out a
few mainly weak thunderstorms Tuesday as some weak instability
develops behind the warm front especially south of I-16. Winds
will pick up Wednesday night and remain elevated through
Thursday as the pressure gradient increases and could see gusts
at least near 35 mph especially near the SC coast. A Lake Wind
Advisory could also be needed for Lake Moultrie.
Temperatures should be above normal through Wednesday night,
then well below normal Thursday when temperatures should
struggle to rise out of the 40s during the day, especially
inland areas.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Models are in fairly good agreement through the long term
period with much cooler weather on tap late week. Any
precipitation should end Thursday night as offshore low pressure
pulls farther away with relatively quiet weather then returning
until warmer weather and rain chances increase Sunday night as
the next storm system approaches. Temperatures should be well
below normal through at least late week before possibly getting
back above normal late in the period.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
Prior to the 0Z TAFs: Regional observations were generally MVFR
with pockets of VFR near the coast. I anticipate that MVFR
ceilings will develop over the terminals this evening. Late
tonight, A warm front is expected to lift north, arching around
sfc high pressure. The combination of llvl lift over the front
and high BL moisture should support ceilings to lower to IFR at
KCHS, lower at KSAV. In fact, high resolution guidance and SREF
probs indicate that conditions will fall to LIFR during the
pre-dawn hours. A large patch of showers should pass west to
east across the terminals during the daylight hours Tuesday. The
rain showers may result in unsettled flight conditions, but
should favor IFR to MVFR conditions through most of the day.
Extended Aviation Outlook: High confidence in some significant
restrictions at KCHS/KSAV through Thursday night with VFR
returning Friday. Also, strong northeast winds gusting over 20
knots are expected Wednesday night through Friday.
&&
.MARINE...
Tonight: The local waters will be situated between high
pressure inland and a weak offshore low for the first part of
tonight. This will drive modest northeast flow through this
evening, with speeds topping out in the 10-15 knot range. Winds
will drop off to less than 10 knots late, but will likely remain
out of the northeast ahead of a warm front lifting northward.
Seas will average 2-4 feet. Can`t rule out patchy fog in and
around the Charleston Harbor late tonight. Overall confidence in
fog is low.
Tuesday through Saturday: Moderate confidence this period.
Generally no significant concerns until late Wednesday after a
strong cold front moves through, although some dense sea fog
could develop across the nearshore waters Tuesday/Wednesday.
High risk for Small Craft Advisories for all waters Wednesday
night into Saturday, except probably just through Friday for
Charleston Harbor, with Gale Warnings possible Thursday into
Friday night especially eastern waters near the Gulf Stream.
&&
.TIDES/COASTAL FLOODING...
Increasing northeast winds Thursday into Friday behind a strong
cold front could push tide levels high enough to cause minor
saltwater inundation, especially along the SC coast.
&&
.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.
&&
$$
NEAR TERM...NED
SHORT TERM...RJB
LONG TERM...ETM
AVIATION...NED
MARINE...BSH/RJB
TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Des Moines IA
552 PM CST Mon Feb 17 2020
.UPDATE...
Issued at 551 PM CST Mon Feb 17 2020
Finally seeing changeover to snow over the northern areas with
some heavier snowfall rates expected in the advisory area. Have
extended the advisory to 03z due to potential to linger into the
evening hours. North of the border in Minnesota, areas along the
cold front and weak low already much worse. Though totals here
should still be in the 1 to 2 inch or so range, conditions will
continue to deteriorate in the next hour to three hours. Also,
added an SPS for patchy dense fog over eastern and portions of
southeast Iowa where moisture convergence along the warm front
extending from the weak low over southern Iowa continues to focus
boundary layer saturation. Expecting with the eastward translation
of the low that a period of 2 to 3 hours of fog will be the
primary length. Currently worse along the I80 corridor from east
of Des Moines to Grinnell. /rev
&&
.DISCUSSION.../Tonight through Monday/
Issued at 235 PM CST Mon Feb 17 2020
Main Points
Wintry precipitation still anticipated over north central Iowa late
this afternoon and evening, which could lead to some travel
impacts. Confidence in snow totals is quite low due to the
potential for mixed precipitation types and near to above
freezing surface temperatures. Cooler conditions through the
middle of the week with perhaps some light snow in western Iowa on
Wednesday. Warming trend follows to end of the week as highs
return to the 30s and 40s by the weekend. Pattern looks more
active late weekend into next weekend which could bring more
chances for rain/snow to the region.
Discussion
Primarily zonal upper level pattern undergoes amplification
through tonight as a trough digs into the upper Plains. Broad
warm air advection and upper level forcing has spurred light
precipitation over the state today, mainly near and ahead of a
cold front nosing into western Iowa. As of 20z RAP analysis has
the surface wet bulb zero line near the Minnesota border, although
this may be a bit aggressive compared to surface obs. Strong
consensus amongst observational data sets that the max wet bulb
aloft is greater than +1C over the entire area, so at the very
least low to mid level theta-e advection has been warm enough to
support mostly rain so far today. Hi-res model guidance remains
bullish on the development of a tight mesoscale snow band across
far northern Iowa later this afternoon into early evening. Current
setup is favorable given low static stability and some CI evident
in the folded theta-e contours on cross-sections. Near freezing
wet bulb temps and drier air aloft bring possible p-types into
question. Strong, concentrated lift within a well organized
mesoband could provide enough dynamic cooling to support snow, but
near to above freezing surface temps would help mitigate impacts
and result in low SLRs. GOES infrared imagery also shows pockets
of cloud tops warmer than -10C, suggesting a lack of ice
introduction in some areas. Thus some uncertainty still remains
as to how the next few hours will evolve within the advisory area,
and may just end up with a mixed bag of wintry precip and limited
snow accumulations. Temperatures cool below freezing as the cold
front swings through, but precipitation wanes shortly after and
thus limiting the window for additional accumulating snowfall.
Further south light rain is possible until the front swings
through late this afternoon and evening. Cannot rule out a few
rumbles of thunder and some small hail/graupel with MUCAPE progged
between 50-100 J/kg.
Beyond tonight the forecast turns cooler through the middle of the
week. Next precip chances clip western Iowa on Wednesday as a
shortwave trough digs south out of the Canadian prairies. Upper
level forcing is not overly robust with this system and moisture
is marginal, so not expecting much more than just some light snow
at this time. Cold 1045mb surface high settles into the state
Wednesday night. Clearing skies and light winds will lead to
optimal conditions for raditional cooling, particularly in north
central Iowa where a more widespread snow pack should exist and
help temperatures fall off into the teens below zero. Temperatures
to the south will not be quite as cold. Southerly flow and a
gradual warm up for the latter half of the week as low amplitude
upper level ridging builds over the region. Highs return to the
30s and 40s, possibly pushing 50 degrees for parts of southern
Iowa on Saturday. Closed low over the southwest US swings east
beneath the ridge by Sunday, although the track of the low remains
quite uncertain. The more northerly GFS would bring rain/snow
chances into at least the southern half of the state, whereas the
Euro prefers a more southerly track and is mostly dry for the
area. Ensemble guidance sheds little light on the most probable
solution with a fair split between wet/dry. Pattern evolution into
the middle of next week looks quite active as all models develop
a large trough over the western states.
&&
.AVIATION.../For the 00Z TAFS through 00Z Tuesday evening/
Issued at 551 PM CST Mon Feb 17 2020
Conditions continue to worsen north sites at KMCW/KALO and briefly
at KFOD for the next 2 to 3 hours. Southeast sees potential for
some fog through 9 pm. Overall, IFR cigs will give way to MVFR and
then VFR conditions aft 04z northwest at KFOD and in the
southeast/east aft 10-14z. Lower visby continues with 1/4sm at
KMCW and 1/2 to 2sm possible at KALO, KDSM, and KOTM next 3 to 5
hours. Northwest winds increasing to 15 to 20kts gust 28kt aft 02z
northwest progressing southeast through 12z. /rev
&&
.DMX WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 9 PM CST this evening for IAZ006-
007-016-017-025>028.
&&
$$
UPDATE...REV
DISCUSSION...Martin
AVIATION...REV
Area Forecast Discussion
National Weather Service Grand Rapids MI
635 PM EST Mon Feb 17 2020
LATEST UPDATE...
Aviation
.SYNOPSIS...
Issued at 330 PM EST Mon Feb 17 2020
- Snow and rain tonight
- Lengthy stretch of dry weather starts Tuesday
- Brief shot of colder air mid week
- Late week warm up with sunshine
&&
.DISCUSSION...(This evening through next Monday)
Issued at 330 PM EST Mon Feb 17 2020
-- Snow and rain tonight --
No big changes to the going forecast. Snow or a mix begins late
this afternoon/early this evening and ends late tonight or around
daybreak. The snow will transition to rain/drizzle near and south
of I-96 toward midnight, but not before a inch or two of wet
slushy snow coats the roads this evening.
Precipitation stays mainly all snow tonight north of M-46, with
highest accumulations of 3 to 5 inches expected near and north of
Route 10, particularly east of Highway 131 around Reed City and
Clare.
Winter Weather Advisory will remain in effect for all areas since
some travel impacts are likely areawide, even where the lower
accumulations are forecast. Another issue is that the more rural
dirt and side roads currently packed with snow will be icy even
from rain.
This is a classic wet-bulb/evaporative cooling event this evening
for srn Lwr MI, where incoming area of rain becomes mostly wet
snow overhead as it falls into a dry air mass and cools the
thermal profile below freezing. Sfc dew points are creeping up,
but are still only in the lower to mid 20s. Latest HRRR suggests
dew points will be 28-32 at 03Z during the height of the event with
wet bulb zero hgts remaining below 1200 ft north and east of
AZO, supporting mostly snow.
A few concerns: While the dry air will promote wet-bulbing, it
could also help to limit the amount of precip we see. In fact QPF
amounts have decreased southeast of GRR in some of the the latest
guidance due to the feed of dry air from the east. Another
concern is that the precipitation upstream is not totally solid
and there`s some gaps over nrn Il... inbetween the area of precip
over central Il and the snow over WI. Lighter and less widespread
precip could make wet-bulbing less efficient and may lead to more
rain than snow, especially over the sw corner of the cwfa.
-- Lengthy stretch of dry weather starts Tuesday --
Guidance has been consistent in showing mostly dry weather from
Tuesday into next weekend as split flow pattern develops and we`re
inbetween the two branches of the jet. Little to no lake effect is
anticipated mid week as the colder air comes in since a large/dry
sfc high of around 1045 mb will dominate much of the nrn U.S..
-- Brief shot of colder air mid week --
Single digit lows are likely on Wednesday and Thursday nights
under the sfc high. Daytime highs on Wed and Thur will be only in
the lower to mid 20s.
-- Late week warm up with sunshine --
Quick shift toward milder weather occurs late in the week as the
sfc high drifts toward the Mid Atlantic. Southwesterly return
flow helps H8 temps rebound from -15 to -20C Thursday to 0 to +5C
by Saturday. Highs near 40 or in the 40s look likely for the
weekend with strong indications of sunshine... especially Fri/Sat.
Southwest winds will be brisk however and that will make it feel
cooler.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
Issued at 635 PM EST Mon Feb 17 2020
Widespread IFR conditions will prevail overnight and then slow
improvement can be expected Tuesday morning with MVFR conditons
by 15Z. Winds will be southeast this evening with some gusts over
20 knots. Winds will go west overnight and northwest on Tuesday
with some gusts over 20 knots.
&&
.MARINE...
Issued at 330 PM EST Mon Feb 17 2020
Northwest winds to 30 knots and waves 4 to 7 feet are expected
to develop very late tonight after the sfc low tracks through, so
Small Craft Advisories are in effect. We have some ice in the
nearshore area now, which will act as a buffer for beach erosion.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 10 PM EST this evening for MIZ064-
071-072.
Winter Weather Advisory until 1 AM EST Tuesday for MIZ050>052-
056>059-065>067-073-074.
Winter Weather Advisory until 10 AM EST Tuesday for MIZ037>040-
043>046.
LM...Small Craft Advisory from 4 AM Tuesday to 11 AM EST Wednesday
for LMZ844>849.
&&
$$
SYNOPSIS...Meade
DISCUSSION...Meade
AVIATION...Ostuno
MARINE...Meade
AREA FORECAST DISCUSSION
National Weather Service Wilmington OH
938 PM EST Mon Feb 17 2020
.SYNOPSIS...
A low pressure system will approach the region tonight and a
cold front will move through the area on Tuesday. High pressure
will then build back into the region for Wednesday and the rest
of the week.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
Showers are moving across west central Ohio and will continue to
do so over the next few hours before heading off to the east.
Forecast become more uncertain south of that area. Low level jet
and associated axis of moisture transport will translate across
the region overnight. However it appears that showers will be
scattered to perhaps numerous and on the light side. Recent HRRR
and RAP runs have been trending drier. Temperatures are likely
near their lows for the night with slowly rising readings
through the overnight hours.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/...
Cold front will be located from northwest Ohio back through
central Kentucky at the beginning of the period. A second wave
of showers will spread across areas south and east of I-71
during the morning. The front will push through the region
during the morning hours, lead to the a non- diurnal temperature
trend. Highs in the northwest could be shortly after sunrise,
while the southeast they could be closer to mid day. As the
front crosses the fa, it should bring an end to the rain.
Another strong high pressure system will begin to build in Tuesday
night. Right now it looks like it will bring clearing skies. Lows
Tuesday night will be back around normal, ranging generally in the
mid 20s.
&&
.LONG TERM /WEDNESDAY THROUGH MONDAY/...
On Wednesday morning, a cold front will be moving well east of the
region, exiting the mid-Atlantic coast. Deep-layer westerly flow
will keep a pseudo-zonal pattern over the Ohio Valley, with a
relatively dry air mass in place over the region. Surface high
pressure is expected to be centered over North Dakota on Wednesday,
gradually moving southeast, and expected to envelop the Ohio Valley
from late Thursday through Saturday evening.
The cold advection pattern in the boundary layer will be well
established at the beginning of the extended forecast period,
bringing cooling temperatures through Thursday night. Also,
additional reinforcement of cold air is expected to arrive on
Thursday morning, as another cold front moves into the region from
north to south. This front is unlikely to produce precipitation, but
in association with an upper level trough moving through at around
the same time, there will likely be an increase in cloud cover on
Thursday. An even colder and drier air mass, associated with the
approaching surface high, will move over the region behind the
front. This will bring the chance for the coldest temperatures of
the week on Friday morning, with clear skies and winds becoming
light -- all within an exceptionally dry air mass. Min temps on
Friday morning are expected to be in the teens.
After the center of the high has passed through the region on
Friday, a gradual shift to rising heights and southerly boundary
layer flow will take place. This will lead to gradually warming
conditions going into the weekend.
Overall confidence remains relatively high with the large-scale
forecast features, at least through Sunday. Uncertainty becomes a
little bit more of an issue with regards to trough development /
surface cyclogenesis occurring on Sunday over the southern plains,
then moving eastward into the lower/middle Mississippi Valley region
on Monday. This system appears like it will eventually spread
precipitation into the Ohio Valley at some point late in the
extended forecast period, but PoPs will be kept at 20-30 percent
at this distance in the forecast.
&&
.AVIATION /03Z TUESDAY THROUGH SATURDAY/...
VFR conditions will persist through the early part of the TAF
period with winds veering to the south and increasing slightly.
As a low level jet translates across the region, there will be a
brief period of low level wind shear at most sites overnight.
Rain will spread across the region after 06Z, and while it does
not look particularly heavy, it will moisten the low levels.
This will result in MVFR ceilings developing and then fairly
quickly falling to IFR region wide. Some visibility
restrictions will also occur with the low ceilings, at least
until a cold front passes on Tuesday morning. Once this occurs,
visibilities will improve first. Then expect ceilings to lift to
MVFR with some breaks in this lower deck. There could be some
further improvement in ceilings late in the period, mainly in
the Cincinnati area.
OUTLOOK...MVFR ceilings will linger into Tuesday night.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Novak/Sites
NEAR TERM...
SHORT TERM...Sites
LONG TERM...Hatzos
AVIATION...
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Jackson KY
1013 PM EST Mon Feb 17 2020
.UPDATE...
Issued at 1013 PM EST MON FEB 17 2020
Decided to go ahead and stick with earlier trend of slowing down
precipitation onset and not having rain entering forecast area
until around 12Z, which is about 3 hours earlier then day shift
forecast. Of note, the departing dayshift forecast did mention
that it may be necessary to slow down precip onset tonight due to
large amount of dry air that is currently in place. Ingested the
latest obs into the forecast grids to establish new trends.
Updated zone forecast text product has been issued.
UPDATE Issued at 636 PM EST MON FEB 17 2020
The 18Z run of model data has suggested that precipitation onset
will be a few hours slower than previously forecast. With the
latest CONSHORT, NAM12, GFS, and HRRR models all suggesting a
slower onset, decided to go ahead and update the forecast to
reflect this new timing. This supports the idea that dry air that
is currently in place could hinder the eastward progression precip
in our area and the ability of said precip to reach the ground
before evaporating. Also ingested the latest obs into the
forecast grids to establish new trends in the very near term.
&&
.SHORT TERM...(This evening through Tuesday night)
Issued at 353 PM EST MON FEB 17 2020
The current surface analysis as of 20Z features high pressure over
the Northeast retreating east. To the west, crossing the central
Plains is the next low pressure system developing and shifting
east. This feature will begin to move into the OH Valley tonight
into tomorrow morning. The one forecast challenge setting up for
this system is the dry surface layer. Dew point depressions
across the area are on the order of 15 to 20 degrees. This will
make it difficult for the boundary layer to saturate. Thus, have
lowered the pops at onset and brought the bulk of the measurable
rainfall after 08Z. Due to this tonight, there will likely be some
ridge to valley temperature differences as cloud cover will
likely not be thick enough for significant insulation. Have
adjusted the ridge and valley temps for lows tonight according to
this.
By 12Z tomorrow morning, ceilings will finally lower with the
column finally saturating. 850MB winds will be at 40 to 50 knots
with the low level jet impacting the area from the southwest. By
Tuesday morning, a low level inversion setting up will keep the
stronger winds from mixing to the surface but, still some 20 to 30
mph gusts are not out of the question. As well, give weak
instability, have gone with showers across the area but not
expecting thunder at this time. Through the day, southwest flow
will continue with highs reaching into the mid 50s with the cold
front passing through in the afternoon. The air mass moving in
behind this front will bring clearing skies with temps dropping
into the upper 20s for lows. The bulk of the moisture will exit
the area before the colder air changes the precip to snow with the
exception of the higher elevations. Overall, this will lead to
more normal values for lows Tuesday night.
.LONG TERM...(Wednesday through Monday)
Issued at 320 PM EST MON FEB 17 2020
Models are in good agreement with features aloft through the period.
Interestingly, noticed that the 12Z solution of the ECMWF trended
towards the GFS for the last 36 hours of the extended, where some
significant differences had previously existed. The pattern is best
described as a mean zonal flow regime with two main features of
interest, the first a northern stream positively tilted trough that
will drop southeast across the eastern CONUS Thu/Fri. The second
feature will be a southern stream trough or low that will lift out
of the far southwest, push through the Great Plains and into the
Tennessee/Ohio valley regions by the end of the forecast. At the
surface, strong Canadian high pressure will build into the eastern
half of the nation, tracking from the Northern Plains to the
Appalachians during the first 72 hours of the period. A disturbance
will develop over the far southeast Thu/Fri, a weak reflection of
the aforementioned positively tilted trough. This disturbance will
produce generally light, but widespread precipitation from the
Tennesseee Valley southward. It appears our area remains dry, though
some solutions do suggest a slight chance of precipitation along the
KY/TN state line. Otherwise mid, and especially high level clouds,
will blanket the much of the region. Ridging aloft and surface high
pressure will then transit the Ohio and Tennessee valleys.
Thereafter, a storm system approaches from the west by the end of
the weekend or start of the following week.
Sensible weather features generally dry weather through the period.
With Canadian high pressure ushering in dry/colder air into the
region and high pressure centered over the central Ohio Valley
Friday and Saturday morning, expect temps to run below normal for
that time frame. Temps look quite cold (into the teens) by Friday
morning and while closer to normal, still drop to around 20, or mid
20s Saturday morning. A few locations in our typically colder
eastern valley areas could slide into the mid teens again Saturday
morning. Thereafter, temps moderate through to the end of the
forecast with an increase in clouds and the threat of precipitation
as our next weather maker approaches from the west.
&&
.AVIATION...(For the 00Z TAFS through 00Z Tuesday evening)
ISSUED AT 639 PM EST MON FEB 17 2020
Expect VFR conditions to begin the TAF period with generally
light and variable winds. Winds will slowly begin to increase out
of the south through tonight and into tomorrow morning before
shifting to the southwest. Ceilings will begin to drop tonight as
the cold front approaches from the west. Expect some below IFR
cigs by 12 to 13Z with rain dropping vis to IFR conditions as
well. These conditions will then persist through the rest of the
TAF period. The one thing in question at this point, is how fast
will this drop in conditions occur. Dry air in place, may hinder
the drop in cigs and vis pushing the occurrence back a few more
hours, which is now reflected in the TAF forecast.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
UPDATE...AR
SHORT TERM...SHALLENBERGER
LONG TERM...RAY
AVIATION...AR
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Charleston WV
857 PM EST Mon Feb 17 2020
.SYNOPSIS...
Damp Tuesday with rain developing ahead of a cold front that
will arrive late Tuesday. Colder and drier for the end of the
week with high pressure.
&&
.NEAR TERM /THROUGH TUESDAY/...
As of 847 PM Monday...
Have made a couple of changes to the inherited forecast,
including adjusting hourly temps and overnight lows for tonight.
Many of the smaller valleys across the lowlands have already
dropped into the low to mid 40s while area ASOS/AWOS observation
sites at higher airport elevations remain around 50 degrees. As
such, I`ve trended the overall temp forecast to account for
this. Official lows tonight may occur late evening and then
slowly rise closer to sunrise as warm air advection strengthens
(especially so for locations above 2.5kft).
Also slowed down arrival and departure of precip for Tuesday.
There is still quite a thick and stout dry layer in the lower
levels tonight that will take awhile to overcome. Last several
runs of the HRRR have indicated a slower development and
associated progression of precip on Tuesday with time-lagged
models also indicating a greater likelihood of delayed arrival.
As of 200 PM Monday...
High cirrus passing through the Central Appalachians this
afternoon hasn`t put a stop to southerly flow and warm air
advection from taking place. Generally went a few degrees warmer
than guidance for today based on how warm we already are at the
time of this issuance, per local and regional observations.
However, clouds will begin to lower and thicken this evening as
a warm front lifts northward, precluding the next disturbance
ejecting out of the midwest overnight. PWATs will be on the
increase as well overnight, setting up for a wash out of a day
tomorrow. The rain shield will mark the location of the cold
front which will cross from west to east through the day
Tuesday, making it over the mountains by the evening.
Thermal gradient sets up overnight tonight with a cold wedge
along the spine of the Appalachians. Embedded light POPs
within the wedge may allow for a slight chance of light snow
showers around midnight tonight, then transitioning back into
snow as 850mb temperatures rebound above freezing.
Opted to delay the onset of rain in our northwestern zones late
tonight as moisture overcomes dry air established in the low
levels of the atmosphere from today. This coincided well with
the thinking of our neighboring offices, so as it currently
stands I have rain entering into Perry County during the predawn
hours then engulfing the forecast area by the morning rush
hour. May have gone a bit overzealous with POPs in the southern
coalfields for Tuesday morning, but I do expect categorical POPs
by the afternoon as the front continues its pursuit eastward.
Precip winds down heading into the end of the near term, with
colder air right on its tail. It won`t be fast enough to inflict
a changeover to frozen precipitation in the lowlands, but
perhaps over the mountains late Tuesday night.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
As of 215 PM Monday...
Cold front slips southeast Tuesday night with drier and colder
air advecting in from the northwest for Wednesday. Model
soundings indicate some low level moisture may linger beneath a
developing subsidence inversion which may keep some clouds
around through the day.
An upper level system will drop south through the Plains,
eventually interacting with the old frontal boundary draped
along the Gulf Coast Thursday and Thursday night. This will
help to induce surface cyclogenesis which will track east off
the Southeast coast. This will likely just impact the area with
some mid and high level clouds as a strong surface high
traverses down the MS River valley.
Temperatures will start mild and end below average Thursday and
Thursday night.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
As of 220 PM Monday...
Aforementioned surface high will make its way toward our region
Friday and Saturday while weakening. An abundance of dry air
through the column will likely mean quite a bit of sunshine for
a change. This won`t last as the next system approaches from the
west Sunday night and Monday with rain chances increasing.
Temperatures will moderate back above normal for the weekend.
&&
.AVIATION /02Z TUESDAY THROUGH SATURDAY/...
As of 637 PM Monday...
VFR nearly areawide for most of tonight, but rapidly
deteriorating flight rules during the day Tuesday.
Mid level cloud deck currently moving east across the area with
a lack of low level moisture precluding any impacts from CIGs
tonight. By late tonight (and moreso after sunrise Tues),
SSErly llvl flow will promote more significant moisture
advection with rapidly lowering CIGs from VFR to MVFR. Numerous
SHRA to even widespread RA should develop and spread from west
to east Tues morning, aiding in a further deterioration of
flight rules to IFR at times. Precip should end from NW to SE in
the afternoon as a sfc front moves through the area, however
some -RADZ may persist even into the late hrs of the TAF period
from KBKW to KEKN (with improving flight rules elsewhere).
Some variable winds early in the TAF period should become more
SErly overnight...strongest at KBKW/KEKN/KCRW (sustained 5 to 15
kts and gusty at times) and closer to 5 to 10 kts elsewhere.
Winds veer more SWrly during the daytime hours Tues and
eventually NWrly after FROPA mid/late afternoon.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z WEDNESDAY...
FORECAST CONFIDENCE: High tonight. Medium Tues.
ALTERNATE SCENARIOS: Non-convective LLWS may need to be included
in future TAF pkgs for the overnight hours of tonight. Timing of
arrival of precip and lower flight rules on Tues is a bit
uncertain, but may occur sooner than currently forecast.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE TUE
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11
EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06
CRW CONSISTENCY H H H H H H H H H H H H
HTS CONSISTENCY H H H H H H H H H H H H
BKW CONSISTENCY H H H H H H H H H H H H
EKN CONSISTENCY H H H H H H H H H H H H
PKB CONSISTENCY H H H H H H H H H H H H
CKB CONSISTENCY H H H H H H H H H H H H
AFTER 00Z WEDNESDAY...
No widespread IFR conditions expected at this time.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...None.
OH...None.
KY...None.
VA...None.
&&
$$
SYNOPSIS...30/MEK/RQH
NEAR TERM...RQH/MEK
SHORT TERM...30
LONG TERM...30
AVIATION...RQH