Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/15/18
Area Forecast Discussion
National Weather Service Caribou ME
922 PM EST Wed Feb 14 2018
.SYNOPSIS...
Low pressure will track to our north on Thursday. A cold front
will approach Thursday night into Friday and cross the area
Friday evening.
&&
.NEAR TERM /THROUGH THURSDAY/...
9:22 pm update: Stratus is seen on satellite and has spread
east across northern Maine this evening. It covers most of the
area from northern Somerset County to central Aroostook County.
There are some breaks in the clouds, and as of 9 pm some holes
in the clouds were visible at WFO Caribou. The cloud deck is at
around 2500 to 3500 feet. Across the remainder of the CWA the
sky is clear. The stratus may expand south into parts of
interior Downeast by morning, but it is also possible that the
clouds never make it south of Lincoln by morning. Adjustments
were made mainly to the sky grids based on the latest satellite
trends and observations. Some tweaks were also made to the
hourly temperatures and overnight lows.
Previous discussion...
Mild weather will continue into Thursday. Temps have risen well
into the 30s across much of the CWA w/sites across Downeast
seeing lower 40s. So, some melt was occurring. The latest satl
imagery showed some partial clearing and this is expected
through the evening. Temps will drop off after sunset for a
while given dewpoints still in the teens and lower 20s. Temps
look like they will level off later at night as a light ssw wind
sets in. The NAM and RAP soundings both show an inversion
setting up overnight w/moisture getting trapped below 2000 feet.
Given this and the ssw wind aloft, decided to bring some low
clouds into the region overnight into Thursday. The short range
guidance including the GEM, HRRR and GFS show some light precip
moving into western areas overnight into early Thursday morning.
This precip looks to be in response to disturbance aloft moving
across the region. There could be a brief period of light
freezing drizzle or flurries across the western and far northern
areas into Thursday morning. Most of this activity will be
aloft and very light. Not expecting any problems w/this
potential. Temps overnight are expected to be in the 20s
overnight. Some low lying sites could see upper teens given the
inversion.
For Thursday, temps will start their rise as a warm front lifts
across the region during the day. This front looks like it will
trigger some light snow showers or rain showers especially in
the afternoon. There could be some light freezing drizzle in the
morning. Best chance for anything measurable will be across the
far north and west. Afternoon temps are forecast to reach well
into the 30s across the northern 1/2 of the CWA w/lower 40s
central and Downeast.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
Low pressure will lift to our northeast Thursday night while
another weak area of low pressure tracks east across the Gulf of
Maine. Expect mainly cloudy skies Thursday night with the
chance of northern snow showers and rain or snow showers down
east. A arctic boundary will cross the region on Friday with
snow showers across northern and central areas and perhaps a
snow squall. Much colder air will follow the frontal passage for
Friday night. After an unseasonably warm Thursday night with
lows only in the low to mid 30s, low temperatures Friday night
will fall into the single digits below zero across the far north
and the single digits above zero across much of the rest of the
area by Saturday morning. Saturday is shaping up as an
unseasonably cold but dry day as high pressure builds east.
Highs on Saturday will range from the mid to upper teens north
and low to mid 20s down east.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Saturday night we will need to keep any eye on on area of low
pressure that will be moving east of the mid atlantic coast. 12z
operational models keep the low well south of the Gulf of Maine
putting the down east coast on the northern edge of the
precipitation shield. There are some ensemble members that
favor a track a bit closer to the area. A model blended
solution yields chance pops reaching all the way into northern
areas by later Saturday night and Sunday morning. In any event,
the system will be a progressive open wave with any snow early
Sunday diminishing by afternoon. Expect fair weather Sunday
night and Monday as high pressure builds back in. Forecast
confidence for the early to middle part of next week is not all
that great. Uncertainty exists with regard to the extent of the
upper ridging along the east coast next week and just where a
frontal boundary will set up, separating much milder air to our
south and colder air to our north. The latest EC is stronger
with the ridging into northern New England than the latest GFS
is. Just exactly where the boundary sets up will determine the
type and extent of any precipitation. This is way out there so
just followed a model blended solution yielding snow or rain
chances by Tuesday and Wednesday of next week.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
NEAR TERM: High end MVFR to low VFR at the northern terminals
tonight with VFR at KBGR and KBHB. MVFR for the most part Thu.
SHORT TERM: MVFR or lower conditions possible Thursday night in
low ceilings and snow rain showers. MVFR or lower is possible
on Friday with the passage of an arctic cold front. Best chances
for IFR conditions will be across the north on Friday with
potential snow showers or squalls. VFR conditions return
Saturday through Monday. Small chance we could see MVFR or lower
in snow KBGR/KBHB Saturday night into early Sunday.
&&
.MARINE...
NEAR TERM: The SCA remains in effect for the outer zones
through 3 AM. Winds and seas are forecast to drop off below 20
kts and 5 ft respectively early Thu morning. Expecting
conditions to remain below SCA into Thursday.
SHORT TERM: Strong SCA or even Gale Force Wind gusts could be
expected in the northwest flow behind an exiting cold front
Friday night and Saturday.
&&
.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...Small Craft Advisory until 3 AM EST Thursday for ANZ050-051.
&&
$$
Near Term...CB/Hewitt
Short Term...Duda
Long Term...Duda
Aviation...CB/Hewitt/Duda
Marine...CB/Hewitt/Duda
Michigan. Timing offered by the previous forecast discussion remains
on target and is expected to begin lifting across the border and
into southern sections of the forecast area by 00Z this evening.
Overall activity is tied to the lead edge of a prior nocturnal jet
cycle that will only become accentuated along the southeast flank
of a midlevel cyclonic circulation over portions of WI/IL and Lake
Michigan. Deterministic solutions have been onto this moisture surge
for days, resolving splotchy qpf for Lower Michigan for the duration
of tonight. Hi resolution models are now onboard with aggressive
resolution of the surface moisture in latest HRRR solutions. Always
difficult to buy all in potential erroneous boundary layer/over
saturated data, but observational evidence upstream shows some vsbys
of less than 1SM with some light precipitation reports. Still not
completely convinced dense fog will develop over the snowpack here
in southeastern Michigan tonight but confidence on this bearish idea
is very low. In fact, did include areas of drizzle and fog in the
public forecast. Future shifts can monitor trends. No moisture or
dynamics supportive for precipitation outside of drizzle.
Early Thursday, theta e plan view progs support the passage of a low
to midlevel cold front that will very efficiently support dry air
advection in the 1000-2000 ft agl layer. This should be enough to
shut down any lingering drizzle into the early Thursday period.
Clouds will likely support temperatures that are cooler than today
for a good chunk of the day until late day warm advection takes a
hold of then. Highs probably wont make it in until Thursday evening.
Late Thursday becomes active for much of Lower Michigan as the next
frontal wave passes through the Ohio River Valley. Highest QPF will
remain well south, but models show a sizable area getting impacted
by overrunning precipitation. Somewhat noisy on which level in the
elevated frontal slope will activate, with latest guidance
suggesting some activity occurring along or north of I 69. Very well
developed 800-600mb frontal slope will be in place directly over the
heart of the cwa which will lead to low static stability in the
midlevels. Fair question to bring up possibility for some thunder
particularly during the 21-02Z timeframe south of I 96. Will not add
an explicit mention at this time with neutral lapse rate structure.
However, strong model consensus exists for convective rain showers
in the 21-02Z within zone of favorable low level deformation. Bulk
of the liquid amounts exceeding .25 inch will occur in that window.
Precipitation to occur ahead of the cold front, which will support
warm precipitation types.
Aggressive surface ridging Friday will lead to dry weather, a modest
northwest breeze, and temperatures ranging in the upper 20s to lower
30s.
High pressure exiting the region on Saturday will bring continued
dry conditions through much of the day as highs top out in the low
30s. A quick-moving upper wave accompanying a jet streak surging
across the northern US will bring a brief chance for snow showers
Saturday evening. An amplifying upper level ridge centered along the
East Coast will then build into the region on Sunday lifting the jet
northward into southern Canada and bringing quiet weather to end the
weekend as highs approach 40.
An active stretch of weather then begins early next week as the
region remains between an amplified ridge along the East Coast and
trough over the Western US. Low pressure lifting across the region
on Monday will act to strengthen a frontal boundary to the west of
SE Michigan while increasing deep southerly flow pulls Gulf moisture
northward over the region. Model guidance is coming into better
agreement that the frontal boundary will remain just west of SE
Michigan while a series of low pressure systems tracking along it
bring a prolonged period of rainfall through Tuesday.
MARINE...
Moderate southwest flow today will begin to decrease into the
evening as a surge of moisture northward brings drizzle and fog into
the Great Lakes region. Milder air will result in more stable
conditions over the lakes and thus winds will be limited to 25 knots
or less. A cold front will drop southward Thursday night and will
result in some stronger northwest winds. The colder air will allow
more unstable conditions and the potential for winds to reach gales
for a short period of time. Anticipate the duration to be short
enough to not issue any Gale Watches at this time. Gusts mainly
around 30 knots will be more likely Thursday night early Friday
morning before a high pressure arrives by Friday afternoon and
brings calmer conditions.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...Dense Fog Advisory until 9 AM EST Thursday for MIZ075-076-082-083.
Dense Fog Advisory from 1 AM to 9 AM EST Thursday for MIZ063-
068>070.
Lake Huron...NONE.
Lake St Clair...NONE.
Michigan waters of Lake Erie...NONE.
&&
$$
UPDATE.......MR
AVIATION.....MR
DISCUSSION...CB/JD
MARINE.......AA
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Sioux Falls SD
505 PM CST Wed Feb 14 2018
.SHORT TERM...(This evening through Thursday)
Issued at 238 PM CST Wed Feb 14 2018
Fairly mild pleasant evening tonight with light winds and mostly
clear skies. Could see some high clouds build north south of I-90.
These high cloud could limit the potential for fog. RAP suggests
the potential fog patchy fog in low lying areas, while the HRRR has
backed off on the idea all-together. Have a mention of fog in the
current forecast, but is fairly localized across far southeast SD
into northwest Iowa.
Cold front works south across the area on Thursday. Cold air lags
behind the front, but once the cold air advection develops in the
low levels, winds should increase driving wind chills into the
single digits and teens. Could also see some light snow develop
mainly along and north of I-90. Not a lot of lift but a fairly deep
dendritic layer in the near surface layer develops as temps tumble.
Snow amounts should be fairly light, generally 1/2 an inch or less.
Heaviest accumulations are expect across central South Dakota, where
slightly better dynamics exist.
.LONG TERM...(Thursday night through Wednesday)
Issued at 238 PM CST Wed Feb 14 2018
The extended starts off and ends cold, with a brief warm up in
between. Thursday night, temperatures will fall to near zero, and
with relatively brisk north winds through the night, could see wind
chill values of -10 to -20 below. Developing southwesterly flow
aloft throughout the day on Friday will help draw warmer air into
the region. The mild temperatures last through Sunday, when a strong
cold front associated with a low pressure system moves along the
northern edge of the US. Have raised winds closer to CONSMOS Sunday
into Monday. Behind the front, several mid level waves move through
associated with a large upper trough creating periodic chances of
precipitation from Sunday night through at least the first half of
next week. Details of the various waves are still model specific, so
left pops broad brushed for now. Behind this system, below normal
temperatures look to reign with 925 hpa temps remaining in the teens
below 0C.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 459 PM CST Wed Feb 14 2018
Winds will drop off later this evening, and could see patchy fog
develop in lower lying areas. Will see an increase in high clouds
from the south later tonight which may limit additional fog
development. A frontal boundary will slide through the area on
Thursday, with winds transitioning to northerly and picking up
during the afternoon. May also see light snow develop behind the
boundary, with the potential for the greatest impact being at
KHON by 17Z.
&&
.FSD WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
IA...None.
NE...None.
&&
$$
SHORT TERM...BT
LONG TERM...BT
AVIATION...JM
Area Forecast Discussion
National Weather Service Wilmington OH
905 PM EST Wed Feb 14 2018
.SYNOPSIS...
Showers that formed in a warm and moist southerly flow ahead of a
slow moving cold front will move east this evening, leaving cloudy
skies and patchy fog. An upper disturbance interacting with the
cold front will produce widespread showers on Thursday. Drier air
and colder temperatures are expected Friday with high pressure
arriving behind the cold front.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
As deep-layer moisture has largely departed the area, rain
showers have been replaced by drizzle, coming out of cloud decks
that remain below 1kft AGL. With continued warm and moist flow
in the lower levels, and a dry layer above 650mb (as sampled by
the 00Z KILN sounding), this thick moisture near the surface
will likely remain in place under the inversion -- with drizzle
expected to remain a possibility through the overnight hours.
Areas of fog have also continued across the northern half of the
forecast area, with a few 1/4SM observations mixing in from time
to time. HRRR visibility projections suggest this fog will
continue for another few hours, before starting to gradually
improve (or shift north) going into the early morning.
For the forecast, PoPs were dropped considerably with a change
to drizzle as the main weather type overnight. No significant
changes to the fog / temperature / dewpoint forecasts were
required. Temperatures are actually still very slowly rising,
which should be the trend through the morning.
Previous discussion >
Showers that have formed in a moist southerly flow near an ill-
defined warm front will translate eastward across the FA, with
precip diminishing this evening. A few thunderstorms developing
in a layer of elevated instability containing ~200 J/KG CAPE
will weaken and end as the short wave triggering the instability
moves east. Overnight, a few showers may linger, skies will
stay cloudy, and patchy fog may form in nearly saturated low
level moisture over cooler ground. With a persistent southerly
flow carrying warmer air, temperatures are not forecast to fall
much if at all, with lows ranging from the mid 40s north up to
the upper 50s south.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/...
Thursday will see ingredients for widespread rain showers
coming into phase. As ample moisture advection continues in a
southerly flow ahead of a slow moving cold front, short wave
energy will trigger a surface low along the front. A swath of
showers will develop and move into the area in enhanced lift
surrounding the surface wave, with the main focus of showers
being roughly along I-70 during Thursday afternoon.
As the cold front strengthens and accelerates in response to
increasing jet stream winds, showers will continue Thursday
night, while the bulk of showers shifts toward Southeast Ohio
behind the departing surface low. Drier conditions should begin
to arrive ahead of high pressure by late Thursday night.
Models predict rainfall amounts of around one inch. Localized
flooding potential seems rather low so held off on a flood
watch, though ponding may be a concern.
High temperatures rising well above normal will reach around 60
north up to around 70 south.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
Drier air will work in from the northwest behind the cold front
through the day Friday. This will allow for pcpn to end behind
frontal passage. In the CAA pattern, temperatures will slowly fall
into the 30s through the day.
Surface high pressure will quickly traverse the region Friday night.
Dry weather is expected with lows in the 20s.
For Saturday, a s/wv will approach the region from the west. This
will perturb a weak area of low pressure along the old frontal
boundary to our southeast. Dynamic lift will pull moisture northward
with the likelihood of pcpn expected across our south/east with a
chance of pcpn west. There could be a little snow mixed on the
northern/western fringes, with little if any accumulation expected.
By Saturday night, the weather system will quickly exit east with
pcpn ending.
For Sunday, we will once again see a brief reprieve in the wet
pattern with high pressure expected across the Ohio Valley. Highs
will range from the 40s to around 50.
Upper level pattern across the CONUS will become more amplified as
we head into next week. This will bring back the wet pattern as
embedded s/wvs in the flow combine with a slow-moving boundaries to
bring periods of showers, some of which may be locally heavy. This
pattern will keep the flood threat going for our region, including
river points. Likely PoPs were used for Monday and Tuesday, with
chance PoPs lingering into mid/late week. Persistent southerly flow
will keep temperatures warm until at least mid week.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
IFR conditions are expected to continue this evening and into
the overnight hours, with some LIFR ceilings in the near term
and the potential for LIFR visibilities over the next several
hours as well. Precipitation is changing to a mix of light rain
and drizzle, and this will be included in the TAFs as well.
As the overnight hours progress, a very slow improvement in
conditions will allow ceilings to get more toward the high end
of the IFR range (or even the low end of the MVFR range) by
morning. There will still be a chance of some light rain or
drizzle going into Thursday morning, but not as likely as
earlier in the period.
More rain is expected to move into the area during the afternoon
on Thursday, eventually bringing IFR conditions again. Some
pockets of heavier rain will be capable of IFR visibilities as
well.
Winds through the period will generally remain out of the
southwest at around 10 knots. These values may increase slightly
later on Thursday.
OUTLOOK...MVFR to IFR conditions are expected to continue
through Friday.
&&
.ILN WATCHES/WARNINGS/ADVISORIES...
OH...None.
KY...None.
IN...None.
&&
$$
SYNOPSIS...Coniglio
NEAR TERM...Coniglio/Hatzos
SHORT TERM...Coniglio
LONG TERM...Hickman
AVIATION...Hatzos
Area Forecast Discussion
National Weather Service Lincoln IL
909 PM CST Wed Feb 14 2018
.UPDATE...
Issued at 909 PM CST Wed Feb 14 2018
Dense fog has already developed and will continue to spread
tonight across northern parts of the area. Have already updated to
account for the dense fog and have issued a dense fog advisory for
overnight through tomorrow at 10am. Some areas will likely improve
sooner in the morning while some areas in the extreme northern
parts of the CWA may not improve much at all, but 10am seems like
a happy middle. Since already updated once and other parameters
are looking good, no further updates are needed at this time.
&&
.SHORT TERM...(This evening through Thursday)
ISSUED AT 310 PM CST Wed Feb 14 2018
The main concern in the short term is the coverage of fog,
potentially dense fog, overnight into Thursday. High resolution
guidance is generally overdoing the amount of coverage of 1/4 mile
fog, and shows trends of the fog shifting farther north of I-74
this evening. Later tonight, areas of dense fog are forecast by
the HRRR and RAP models to expand southward into our counties, at
the same time as a band of fog expands into our southern counties,
roughly between I-72 and I-70 from Shelbyville and east. Bufkit
soundings are complicating the matter even more, showing a
potential for the fog to mainly become a very low stratus deck
instead. There remains enough uncertainty to where a dense fog
advisory would be needed, and after collaboration with
surrounding NWS offices, we will not issue a dense fog advisory
this afternoon for the tonight into Thursday period. Fog trends
will need to be closely monitored however.
Despite some brief thinning of the clouds in our SW counties this
evening, clouds should dominate the skies tonight. The blanket of
clouds along with southwest winds will help to keep low temps on
the mild side, to say the least. Lows will be near normal highs
for mid February. Areas near Galesburg will bottom out in the
upper 30s, while areas south of I-70 see lows in the lower 50s.
Lows may actually occur earlier tonight, as temps remain
relatively steady or slowly rise late. The warm temps tonight and
Thursday will go into melting quite a bit of the remaining snow
cover across our northern counties, adding fuel to the potential
for dense fog.
Highs on Thursday will have a large spread from NW to SE across
our forecast areas. That will have something to do with the path
of a surface low across north-central Illinois. It will be cooler
to the north of the track and very mild south of the track. A cold
front extending south from the surface low will progress toward
the Illinois River Valley by 6 pm Thursday. The end result will be
likely chances of rain through the day, with no thunderstorms
expected. MUCAPEs in our SE counties remain less than 100, so we
left thunder out for now. There will be a wide range of high
temps across central IL. We expect upper 40s near GBG, with mid to
upper 60s south of I-70.
.LONG TERM...(Thursday night through Wednesday)
ISSUED AT 310 PM CST Wed Feb 14 2018
Thursday night, the cold front will push across the southeast half
of our forecast area. Likely rain chances should be mainly
confined to areas east of I-55, and especially east of I-57.
As the precipitation comes to an end late Thursday night, there
could be a brief transition to some light snow, but it should melt
as it hits the ground. The bulk of the cold air will arrive on
Friday and Friday night, as high pressure settles southeast from
the Plains. Some brief rain showers could linger south of I-70
early Friday morning, then dry conditions should occur the rest of
the day Friday and Friday night. Despite some sunshine on Friday,
highs will be limited to the mid 20s near Galesburg, with low to
mid 30s in the central portions of the CWA, and upper 30s south of
I-70. Lows Friday night will be the coldest of the next week, as
readings drop into the lower teens in the NW and mid 20s in the
SE.
A warming trend is forecast for Saturday through Monday,
highlighted by a warm front lifting into central IL on Monday.
High temps will climb into the upper 30s to low 40s Saturday,
reaching the upper 40s to upper 50s on Monday.
Rain chances look to be confined to Saturday afternoon in our
E-SE counties due to a low pressure system passing by to the S of
Illinois. Dry conditions look likely from Saturday night through
Sunday evening, before the approaching warm front and baroclinic
zone increase precipitation chances again. The precip type looks
to be mainly rain for Monday and Monday evening, before low
pressure and a cold front arrive and snow chances increase NW of
the Illinois river after midnight Monday night. Rain chances will
continue on Tuesday as the surface low and cold front advance east
of Illinois. Model differences in timing of that system have
caused the blended extended to contain chances of rain Tuesday
night and Wednesday, when there should be a dry period developing
at some point in that time frame.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 557 PM CST Wed Feb 14 2018
Conditions have improved in some areas but am expecting them to go
back down, especially at BMI and possibly at PIA as well. MVFR
cigs at CMI and DEC should improve to VFR later tonight, but
models indicate lower cigs will return overnight and continue
through tomorrow. SPI is VFR but lower cigs also will be
returning late overnight. PIA looks good now, but they also will
be going down to IFR and then LIFR overnight and through tomorrow.
BMI should remain IFR for several hours, but also decrease back to
LIFR overnight. Some improvement is possible late in the period as
a cold front approaches and begins to move through the sites.
Winds will be south to southwest but then become more west-
southwest ahead of the front.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM CST Thursday for ILZ027>031-
036>038-040>046.
&&
$$
UPDATE...Auten
SHORT TERM...Shimon
LONG TERM...Shimon
AVIATION...Auten
Area Forecast Discussion...Updated
National Weather Service Saint Louis MO
944 PM CST Wed Feb 14 2018
.UPDATE...
Issued at 921 PM CST Wed Feb 14 2018
The forecast the remainder of tonight and through Thursday morning
is anything but clear cut. A defined low level WAA regime is in
place with veering south to southwesterly flow through the lower
trop. Mostly cloudy skies will be the rule tonight resulting from
both a continued increase in high clouds from the Plains and also
increasing stratus. Stratus already blankets the east-southeast
portion of the CWA and the latest GOES East Stratus and Nighttime
Microphysics products are showing the development/spread into
southwest/south-central MO. This later stratus is expected to
continue developing/spreading north-northeast through the night
across the CWA. I think the clouds as well as increasing low level
flow should keep any substantial fog at a minimum. Min temps will
be quite mild for late February and actually above normal highs
for this time of year. Another change was to increase POPs on
Thursday morning, especially for areas along and north of
Interstate 70. The last 5+ runs of the HRRR along with some
support from the NAMNEST and RAP have been showing a rather
explosive development of showers in response to low level WAA and
moisture advection associated with a southwest LLJ and weak ascent
attendant with a migratory impulse aloft. If this precip indeed
pans out and persists through much of the morning, it could have
a negative impact on the highs presently forecast.
Glass
&&
.SHORT TERM... (Through Late Thursday Afternoon)
Issued at 310 PM CST Wed Feb 14 2018
Zonal flow aloft exists over our region this afternoon with
southerly flow at the surface. A strong storm system was anchored
off the southern coast of California. After a relatively mild start
to this morning, and thanks to dissipation of the expansive low
cloud field for most locations, temps have surged well into the 50s
and 60s this afternoon under a filtered sunshine from abundant
cirrus clouds.
A piece of energy will break off from the CA storm system and will
race eastward towards our region by Thursday morning with a larger
piece in tow. This will increase deep lift across our region late
tonight into Thursday as a surface cold front also moves thru the
area.
Abundant high cloudiness from cirrus will continue for many areas
this evening as thicker clouds begin to roll back in. Along with a
steady moderate southerly flow of wind, temperatures will not fall
much overnight, with min temps in the low-mid 50s for many areas
near and south of I-70, and mid-upper 40s for areas to the north.
The threat for rain showers is also expected to hold off until very
late tonight for parts of central MO or into Thursday morning for
most areas near and north of I-70 with this rain threat then
dropping southward during Thursday afternoon with the advent of the
cold front.
Clouds will be another factor in determining how aggressive to
handle what could be a very warm day for February tomorrow, and have
decided to continue a via media with respect to MOS on max temps:
ranging from low 70s for many areas near and south of I-70 to the
low 60s in far northern MO and central IL.
Temperatures will be mild enough to preclude any concerns on pcpn-
types other than all liquid.
TES
.LONG TERM... (Thursday Night through Next Wednesday)
Issued at 310 PM CST Wed Feb 14 2018
(Thursday Night - Sunday)
Cold front will continue to progress southeastward Thursday evening.
Showers are likely along and ahead of the boundary. Some weak low-
level instability so kept mention of slight chance thunder during
the evening hours, mainly across portions of southwest Illinois and
southeast Missouri. An upstream shortwave may also help induce some
more stratiform light rain on the cool side of the boundary
overnight Thursday night. This area may clip portions of
southeastern Missouri.
Strong cold advection takes place most of the day on Friday with a
surface high pressure center sliding down the Missouri River Valley.
Temperatures will much much colder on Friday behind the front. Looks
for highs in the 30s and 40s across the area, or about 30 degrees
colder than Thursday!
Still plenty of uncertainty with the next chance of precipitation
late Friday night and early Saturday. Best chance of precipitation
across the area looks to be across southern sections of the CWFA
where strongest low-level warm/moist advection will reside.
Precipitation type will be problematic as classic battle between the
aforementioned warm advection vs. wetbulbing/evaporative cooling
takes place. Believe a rain/snow mix wording is the best way to go,
leaning toward more snow initially as wetbulbing takes place
transitioning to rain as boundary layer warms well above freezing.
Some minor accumulations are possible but still quite a bit of
uncertainty with respect to precipitation type and northern extent
of stratiform precipitation shield into our area.
A weak warm front is forecast to move through the bi-state area on
Saturday night into early Sunday morning. This will leave the CWA in
the warm sector of a developing cyclone across the Rocky Mountains.
High temperatures are expected to be in the 50s predominantly on
Sunday.
(Sunday Night - Next Wednesday)
Warm and active weather regime still appears likely for early next
week as persistent southwest flow aloft sets up across the mid-
Mississippi Valley. Setup appears conducive to at least a couple
rounds of showers and thunderstorms between Sunday night and Tuesday
night. Moderate to potentially heavy rainfall appears possible, but
the specifics are highly uncertain this far out. Exact placement of
the slowly sagging cold front will be critical and this feature and
its progress will be highly dependent on the strength of the
downstream mid/upper level anticyclone and the strength to the low-
level cold airmass behind the front. At any rate, appears warm and
active ahead of the cold front which should bring at least some
beneficial rainfall to the area.
Gosselin
&&
.AVIATION... (For the 00z TAFs through 00z Thursday Evening)
Issued at 538 PM CST Wed Feb 14 2018
VFR conditions prevail at all the terminals early this evening
with high clouds overspreading the area and stratus across
southeast MO into southern IL. Current thinking is that stratus
will redevelop back to the west across MO late this evening and
overnight, with predominately MVFR flight conditions impacting
the terminals. Also overnight a southwesterly LLJ will develop
across southeast KS and western MO and this will produce LLWS
conditions thru 15Z at KCOU. I think there will be a general trend
for improving flight conditions by late morning as surface winds
increase. Precipitation trends are less defined. A cold front will
be moving through the area during the late morning-afternoon and
present indications are there will be showers ahead of the front.
Coverage and timing of the showers varies amongst the guidance.
There certainly could be higher probabilities at KCOU and earlier
in the day in the St. Louis region.
SPECIFICS FOR KSTL:
VFR flight conditions should prevail this evening then MVFR
stratus is expected to develop and move into the terminal
overnight. Improving flight conditions are expected by midday on
Thursday along with increasing southwest winds. Precipitation
trends are bit harder to define. I kept with the trend of the
previous forecast with showers during the later half of the
afternoon ahead of an advancing cold front. There is some newer
short-range guidance that suggests showers could occur as early as
15-16Z and this will be evaluated in preparation of the next TAF
issuance.
Glass
&&
.CLIMATE...
Record high temperatures for February 15th
STL...75 in 1976
COU...78 in 1911
UIN...74 in 1921
&&
.LSX WATCHES/WARNINGS/ADVISORIES...
MO...None.
IL...None.
&&
$$
WFO LSX
Area Forecast Discussion
National Weather Service Midland/Odessa TX
522 PM CST Wed Feb 14 2018
.AVIATION...
00Z TAF issuance...
No major aviation concerns for the next 24 hours, VFR conditions
expected to prevail at all terminals. Gusty S/SW winds will diminish
this evening however FST and MAF look to remain somewhat elevated
overnight. Moisture return from the SE looks possible later tonight
but confidence is fairly low attm to continue mention of MVFR cigs
at MAF. Will continue to monitor this potential through the night
and make any adjustments if needed. Otherwise, expect winds to
increase again from the SW Thursday afternoon.
&&
.PREV DISCUSSION... /issued 345 PM CST Wed Feb 14 2018/
DISCUSSION...
WV imagery shows the west coast trough has opened, and sits over
SoCal, leaving West Texas and Southeast New Mexico under SW flow
aloft. Morning mid clouds finally dissipated, and afternoon
insolation and SW sfc flow has allowed afternoon temps to top 80F in
many locations.
Overnight, a secondary trough over the PacNW will dig south and
phase w/the first, and set up over nrn Baja over the next 48 hours.
Leeside troughing over the Front Range will veer sfc flow Thu
further to the SW and even W, keeping afternoon highs similar to
today`s. However, mid/hi clouds streaming off the west coast trough
may put a damper on afternoon highs, which may end up a degree or
two cooler than today`s. The NAM depicts a modest mtn wave
signature over the Guadalupes beginning late tonight, and lasting
thru Thu evening, so we`ve upgraded the high wind watch to a warning
there.
Meanwhile, The nrn branch of the secondary trough will keep moving
east, and backdoor a cold front into the area by 12Z Fri.
Accompanying the trough will be a 250mb 180+kt jet moving thru the
central CONUS, which will put West Texas and Southeast New Mexico
under the RR quadrant of the jet Fri/Fri night. This will combine
w/the front and isentropic upglide beginning Fri afternoon for
increasing chances of rain thru Fri night. An atmospheric river of
PWATs 4 std devs abv-normal is still forecast to move over the
region during this time, although latest ensembles have shifted it
north over the past couple of days. Also, models POPs are not quite
as high as the past few runs as well. Still, this looks to be the
best chance of rain for the area in quite some time. Attm, higher
dewpoints look to keep the colder temps at bay until the front
arrives. Even then, freezing temps behind the front should not
arrive until late Fri night, and only then over the far nrn zones.
Forecast soundings show moisture fairly shallow over those areas
by that time, so any changeover will likely be -FZRA...if that. It
must be emphasized that models by this time differ quite
significantly in temp profiles. However, even taking the colder
approach, and FZRA accumulations look to be very light and
isolated.
Rain will taper off Saturday as a tertiary trough drops into the
PacNW. maintaining SW flow aloft over the region. Temps should
rebound quickly to above-normal by Sat afternoon, w/return moisture
resuming Sat night. Sunday night, a dryline sets up mid-CWA, and
enough instability will be in place east of this feature for a
chance of thunderstorms.
By this time, models begin to diverge, but the rest of the extended
looks fairly dry, w/a cold front coming in Tue night.
&&
.PRELIMINARY POINT TEMPS/POPS...
Big Spring 56 81 47 53 / 0 0 0 10
Carlsbad 52 73 48 56 / 0 0 10 40
Dryden 50 78 52 73 / 0 0 0 0
Fort Stockton 55 82 50 63 / 0 0 0 0
Guadalupe Pass 52 66 49 55 / 0 0 10 50
Hobbs 49 73 43 51 / 0 0 10 40
Marfa 42 77 42 69 / 0 0 0 10
Midland Intl Airport 51 79 46 55 / 0 0 0 20
Odessa 52 79 46 56 / 0 0 0 20
Wink 46 80 44 59 / 0 0 0 20
&&
.MAF WATCHES/WARNINGS/ADVISORIES...
NM...High Wind Warning from 11 PM this evening to 10 PM MST Thursday
for Guadalupe Mountains of Eddy County.
TX...High Wind Warning from 11 PM this evening to 10 PM MST Thursday
for Guadalupe Mountains.
&&
$$
27/72
Area Forecast Discussion
National Weather Service New York NY
950 PM EST Wed Feb 14 2018
.SYNOPSIS...
A warm front moves across tonight into Thursday, followed by an
approaching cold front that crosses the area on Friday. High
pressure builds through Saturday morning, and moves off Saturday
afternoon. Low pressure passes to the south Saturday night into
early Sunday morning. High pressure returns Sunday into early
Monday. A frontal system may impact the region late Monday into
the midweek period.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Forecast generally on track for tonight with just minor
adjustments made for timing of the rain.
Rain is quickly moving across PA and will begin entering western
portions of the CWA around 03z. The rain will then quickly
overspread the rest of the region through 06z. The HRRR and
latest NAM seem to have a good handle on the timing and
coverage of the rain. There are no concerns for frozen
precipitation tonight as temperatures will be quite mild and
generally in the lower to middle 40s as the rain occurs.
A middle level shortwave and a warm front are the main lifting
mechanisms for the rain. The shortwave axis quickly slides to
the east early Thursday morning, which will help bring an end to
the rain from west to east. The rain should be offshore with
lingering overcast conditions by day break.
Rainfall amounts should range from around a tenth inland to
around a quarter of an inch near the coast.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...
Airmass behind the warm front gets even warmer. Model 850mb
temperatures will be trending warmer compared to the previous
day, with +7 to +9 on average. Same SW flow will be expected
during the day, but wind direction and cloud timing from the
next system will make temperature forecast a bit tricky for some
parts of the area. Used higher resolution data for winds and
temps. For this forecast package have introduced more of
southerly component to wind compared to previous forecast, and
also have more clouds with a model blend. Therefore have backed
temperatures off some across eastern / coastal sections, and
similar temperatures from the city on west due to wind fetch
over land in these areas. Subsequent shifts will determine
whether to adjust the temperature forecast for Thursday. For now
based on current forecast, only JFK and ISP may come close to
records for the date, otherwise records for Thursday are rather
impressive and difficult to surpass, especially for EWR, NYC,
and LGA.
For Thursday night, next system in good confluent regime gets
here rather quickly and on the heels of the previous system.
Timing is rather quick with a light to steady rainfall arriving
for the late evening into the overnight from west to east. Looks
like a general 0.25 to 0.50 liquid event. A bit more liquid with
this second event due to a good warm tongue and advection push
ahead of the boundary, along with elongated vorticity advection
ahead of the approaching cold front. BUFKIT forecast soundings
show a quick shot of omega at roughly 700-500mb layer.
Cold front should move through Friday morning, and clear east of
the region by the afternoon. Winds will kick up behind the front
as a gusty NW wind follows into late Friday afternoon and
evening. With jet structure aloft still nearby any meaningful
clearing may take awhile into early Friday evening.
&&
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
The quasi zonal flow develops into a large scale northern
trough as one northwestern shortwave moves onshore Thursday into
Friday. The flow will remain rather progressive as another
Pacific shortwave moves onshore late Friday. This wave will
remain south of the region and at this time is still not
expected to phase with another wave tracking through Canada.
Model guidance has been consistent with keeping the track of the
low off the DELMARVA into the mid Atlantic region Saturday
night, with minor variations from run to run. The low track is
south and east of the benchmark with mainly an all snow event,
may be a light rain at the beginning late Saturday afternoon.
The track of the low will depend on any cold air damming with the
high moving off the northeast coast, and may suppress the track
farther to the south. With the progressive flow, the storm will be
quick moving with the precipitation falling Saturday night, ending
across the east Sunday morning. The higher QPF remains offshore. At
this time there may be around a half inch across Long Island and
southern Connecticut. Do not have high enough confidence at this
time for warning level snow and will not mention in the HWO.
However, there is the potential if the track is shifted to the north.
With the quick flow into next week, a weak ridge builds Sunday into
Monday ahead of the next frontal system. A warm front approaches
Monday with the chance of overrunning precipitation. Signals
remain for a significant warmup next week as a ridge builds off
the southeast coast into the midweek period. This will slow the
flow and a series of shortwaves will move through the upper
trough into the midweek, so will have chance probabilities
Monday into Wednesday.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
A prolonged period of SW flow can be expected until a cold front
passes through on Friday.
Cigs will continue to lower tngt as rain overspreads the area.
Cigs could stay vfr at the NYC arpts til around 4z. A break to
vfr is possible during the day Thu, especially across the NYC
arpts. Aft 02Z, additional rain and ifr will sweep into the
area.
Light ssw winds tonight, then winds increase again during the
day Thu. Lgt and vrb flow Thu ngt.
.OUTLOOK FOR 00Z FRIDAY THROUGH MONDAY...
.Thursday Night into Friday...Rain likely with MVFR or lower.
NW winds G25KT Friday afternoon/evening.
.Saturday...VFR.
.Saturday Night...MVFR or lower with a chance of snow.
.Sunday...Improving to VFR.
.Monday...Initially VFR conditions lowering to MVFR or lower
late with rain.
&&
.MARINE...
The forecast is generally on track across the waters. There
could be an hour or two of seas around 5 ft on the offshore
ocean waters east of Fire Island inlet this evening. Seas should
subside to 3 to 4 ft overnight.
Otherwise, a prolonged period of SW flow will prevail through
Friday morning. A cold front passes through during the late
morning and early afternoon on Friday. Seas on the ocean will be
gradually build during this time and will likely exceed 5 ft
late Thursday night and continue to build into the day on
Friday. NW gusts 25-30kt are likely across all waters Friday
afternoon into Friday night behind the cold front. SCA criteria
may occur for the southern most ocean waters as early as late
Thursday night into early Friday morning, with the higher
likelihood of SCA conditions into the day on Friday. A gusty
northwest flow will be ongoing Friday night with SCA level gusts
likely across all the waters Friday evening. With high pressure
building over the waters winds diminish Friday night. Ocean
seas will be slow to subside, falling below 5 feet by Saturday
morning.
Winds and seas are then expected to remain below SCA levels
Saturday through Monday as low pressure passes to the south of
the waters Saturday night, then high pressure builds back into
the waters. Then with an increasing southerly flow ahead of low
pressure approaching Monday ocean seas may build to SCA levels
Monday night into Tuesday.
&&
.HYDROLOGY...
No hydrologic impacts are anticipated with rainfall tonight and
then again Thursday night. Liquid equivalent amounts of 1/10 to
1/4 of an inch are forecast tonight, followed by another 1/4 to
1/2 for Thursday night.
Liquid equivalent precipitation Saturday night into early
Sunday is expected to range from 1/4 northwest to around 1/2
inch through coastal Connecticut and across Long Island.
However, no hydrologic impacts are anticipated this weekend
into early next week.
&&
.EQUIPMENT...
NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) is off the
air for an extended period of time.
&&
.OKX WATCHES/WARNINGS/ADVISORIES...
CT...None.
NY...None.
NJ...None.
MARINE...None.
&&
$$
SYNOPSIS...JE/19
NEAR TERM...JE/DS
SHORT TERM...JE
LONG TERM...19
AVIATION...JMC/MD
MARINE...JE/19/DS
HYDROLOGY...JE/19
EQUIPMENT...
Area Forecast Discussion...UPDATED
National Weather Service Norman OK
848 PM CST Wed Feb 14 2018
.UPDATE...
Allowed the Red Flag Warning to expire for parts of western
Oklahoma this evening. Made small adjustments to all weather
elements tonight, but no major changes.
&&
.DISCUSSION...
Warmer and breezy conditions can be expected tonight.
South to southwest surface winds will continue to bring warmer air
to Oklahoma and north Texas. Don`t think temperatures will fall
much tonight due to the breezy conditions and increasing mid/high
level cloud cover to limit radiational cooling. Surface dewpoints
will be quite high in many locations, in the 50s to near 60F
southeast of a Seymour, Texas to Enid line which is near daily
climatological maximum values for this time of year.
Some patchy fog may occur and reduce visibilities below 3 miles
near and east of Atoka and Durant tonight. Chose not to mention
thinking low level winds will be strong enough (above 10 mph) to
mix the low level moisture into stratus and keep visibilities
above 3 miles in these areas.
Latest HRRR runs have been suggesting some light radar echoes may
occur later tonight into Thursday morning across Oklahoma and
north Texas from some increasing mid level moisture. Do not think
this precipitation will reach the ground due to abundant dry air
between 1500 and 10000 ft AGL.
Near record highs are expected on Thursday. Daily record highs for
February 15 are 81F at Oklahoma City set in 1954, 85F at Wichita
Falls set in 2000, and 83F at Lawton set in 1954. These records
may be in jeopardy.
Wildfire danger will again be Elevated to Near Critical
on Thursday. Will not issue a Fire Weather Watch or Red Flag
Warning at this time for Thursday thinking 20ft winds will stay
generally below 20 mph, especially with abundant mid/high level
cloud cover to limit vertical mixing. However, will closely
monitor as surface winds west of the dryline in western Oklahoma
were much stronger this past afternoon than previously forecast
and depicted by most model guidance.
Products have been updated.
MBS
&&
.PREV DISCUSSION... /issued 553 PM CST Wed Feb 14 2018/
DISCUSSION...
00Z TAFs.
AVIATION...
Most of the signal is that stratus should mainly remain southeast
of the TAF sites tonight/Thursday morning, but there is enough of
a signal of high low-level RHs in the NAM that will at least keep
a TEMPO group with some visibilities of around 5SM and MVFR
ceilings of 015-025 at KOKC, KOUN, KLAW and KSPS. Winds will veer
soon after sunrise Thursday quickly mixing out and MVFR conditions
that do develop. Winds veer above the surface overnight and
become quite strong leading to some LLWS. Have put a generally SW
wind at 020 feet in the wind shear group, but this will be
somewhat variable overnight starting more SSW and becoming more
WSW.
PREV DISCUSSION... /issued 404 PM CST Wed Feb 14 2018/
DISCUSSION...
Strong winds, along with warm and very dry air, have caused
Critical fire weather conditions in far western Oklahoma this
afternoon. Tomorrow promises to be another warm day, although the
axis of maximum temperatures will shift farther east tomorrow.
Though it will again be warm and dry, the approach of a cold front
will dull the south-southwest winds in northwest Oklahoma, but
winds will likely be a problem farther south. Fortunately for fire
concerns, the stronger winds and lower humidities will probably
not coincide tomorrow.
A strong cold front will bring a dose of reality to the region as
winter reasserts itself in Oklahoma and north Texas. Temperatures
will be 30 to 40 degrees F colder Friday afternoon, compared to
Thursday afternoon. Low chances for precipitation will follow the
front, but if any precipitation does occur, it will probably be
very light.
As southerly winds return late Sunday into Monday, moisture and
modest instability will bring our first chance for thunderstorms
in a while. The forecast wind shear, instability, and overall
synoptic setup suggest a possibility of a few marginally severe
storms over the eastern quarter or so of our forecast area.
Another cold front early next week will lower temperatures again,
and some of the expected precipitation may be freezing or frozen
(freezing rain, sleet, or snow). At this time, it appears that
the ice/snow areas will not coincide with areas of significant
precipitation amounts, but we will have to keep an eye on that.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 56 81 32 41 / 0 0 20 10
Hobart OK 52 81 33 42 / 0 0 20 10
Wichita Falls TX 57 84 39 43 / 0 0 10 20
Gage OK 52 78 26 41 / 10 0 0 0
Ponca City OK 58 80 29 41 / 10 10 10 10
Durant OK 58 78 42 46 / 10 10 20 20
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
17/26
Area Forecast Discussion
National Weather Service Blacksburg VA
852 PM EST Wed Feb 14 2018
.SYNOPSIS...
High pressure well to the southeast will weaken allowing a weak
upper level disturbance to cross the area from the west overnight.
A cold front will approach the area from the northwest late
Thursday, but take until Saturday to move through the region.
Unseasonably warm temperatures and widespread rainfall is
expected Thursday through Saturday until the front moves south
of the area.
&&
.NEAR TERM /THROUGH THURSDAY/...
As of 845 PM EST Wednesday...
Showers quickly entering the region from the west and should
overspread the mountains in the next couple of hours before
pushing into eastern sections prior to weakening after midnight.
This supported via the latest HRRR which showers about a 3 hour
window of rainfall along/west of the Blue Ridge through
midnight before moisture shallows out and weak lift heads east.
Cant totally rule out an elevated rumble of thunder mainly far
west otherwise only change was to slow down pops at the onset.
Uncertainty still exists on just how far east rain will make it
given strong westerly flow aloft off evening soundings so going
brief window of higher pops looks good. Otherwise made changes
to lower low temperatures as most already at or below forecast
lows. Should see readings steady out or slowly rise late so adjusted
toward a more uniform non-diurnal curve for lows which puts
most in the 40s outside of the ridges where may stay in the 50s.
Previous update as of 705 PM EST Wednesday...
Generally quiet conditions currently. However, regional radar
mosaic shows band of light to moderate rain with areas of mist
now over the Tennessee Valley and Cumberland Plateau in
Tennessee. This in association with leading edge of warm
front/surge of low-level moisture. Extrapolation of this rain
shield brings it into western Tazewell County around
01-02z/8-9pm and northeast thereafter through 07z. On basis of
good consensus of HREF member reflectivity forecasts as well as
18z guidance, have raised PoPs toward Likely/low Categorical
mainly from the Blue Ridge foothills west/northwest through
07z/2 am, and bumped QPF up a few hundreths of an inch in this
period. Does appear in reflectivity guidance that rain shield
begins to split or break up into two pieces after then. Doesn`t
look like heavy rain but enough to put a potential brief damper
on outdoor plans, especially west of the Ridge. Though patchy
fog also indicated where PoPs are the highest, this is meant to
convey more of a mist than true fog. After rain comes to an end,
have reduced PoPs down to Slight/lower Chance levels into the
morning. May need to increase mist/fog coverage further into
overnight based on METARs in areas currently behind the rain,
though guidance is more bearish on this idea.
Aside from this, temperatures have been running cooler than
previous indications. Have tried to better account for this by
blending in recent GFS LAMP and CONSShort data into the hourly
temperatures. This reduces lows to values in the upper 40s to
mid 50s - all told, a generally small change.
Previous discussion issued at 305 PM follows...
High pressure centered along the South Carolina coastline this
afternoon will move southeast tonight into Thursday. A couple of
weak upper disturbances will rotate eastward across our region.
This will result in periods of rain and drizzle. The best chance of
rain will occur in the western mountains. The ECMWF and GFS looked
overdone with rainfall tonight. Leaned towards the NAM and HRRR for
pops this afternoon into tonight. Added patchy fog to isc grids.
With a 590+dm ridge aloft off the southeast U.S. coast, overnight
low temperatures will be unseasonable mild with readings from the
upper 40s in the mountains to the mid 50s along the western ridges.
Refer Climate section to see Records.
The warm front will continue to lift north on Thursday as the high
center migrates east. Scattered showers are expected especially west
of the Blue Ridge mountains. Rainfall will be less than a quarter
inch. Widespread flooding is not currently anticipated during
daylight hours on Thursday. The axis of the heavier rain will
be northwest of our region generally along the Ohio River.
The west to southwest flow will transport mild air into the region.
High temperatures on Thursday will be challenging record highs with
readings from the upper 50s in the northwest to the lower 70s in the
piedmont.
&&
.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY NIGHT/...
As of 305 PM EST Wednesday...
A cold front will slowly move across the Ohio Valley Thursday night,
then stalls just west of the central and southern Appalachian
Mountains Friday. A series of mid level waves will track along the
front bring moderate to heavy rain to central and northern West
Virginia Thursday night into Friday. By the time this front stalls
to the west of the Appalachians, waves become weaker and moisture
transport will decrease, resulting in light to moderate rain for
southeastern West Virginia and southwestern Virginia. Forecasted
rainfall amounts may range from a half an inch to an inch /0.50-
1.00/ along western slopes Thursday night into Friday. Creeks,
streams and river levels will already have receded from this past
weekend`s event. The ground remains wet but with no snowpack, the
flood threat is low for Friday. The front will move across the area
Thursday afternoon and evening. Winds become westerly quickly,
keeping rainfall amounts along and east of the Blue Ridge to a
quarter of an inch or less. Despite strong pressure rises and a 40
kt low level jet behind the front, subsidence inversion and lack of
strong cold air advection will keep the stronger winds aloft Friday
afternoon/night.
High pressure will move from the Ohio Valley to the mid Atlantic
states Friday night, then wedges south into the Carolinas Saturday.
A disturbance moving over the Tennessee Valley will push overrunning
moisture over the southern end of the wedge during the day Saturday.
Isentropic lift, moist easterly flow and soggy soils could possibly
bring flood concerns to the mountains. This flood threat also hinges
on the amount and duration of rain the area gets Friday. Rainfall
amounts (quarter to half an inch) may trend lower if convection
across the Tennessee Valley develops and tracks southward. Also
complicating the issue is the chance for a wintry mix Saturday
morning, possibly lingering into the afternoon. A secondary wave
develops off the NC/VA coast Saturday evening and quickly pulls the
front across the area.
Record warm low temperatures possible Thursday night with readings
in the 50s. These temperatures are around 30 degrees warmer than
normal for overnight lows and 10 degrees warmer than average daytime
highs this time of year. The warm trend continues Tuesday with
temperatures peaking into the 60s to lower 70s. Areas that have rain
early Friday morning may only have highs in the 50s, still not bad
for February. Temperatures cool down into the 30s following the
front Friday night. Not much warming expected Saturday with a cold
wedge in play.
&&
.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
As of 250 PM EST Wednesday...
High pressure builds in behind Saturday night`s front and wedges
south into the Carolinas on Sunday. A warm front will track over the
wedge bringing another round of precipitation to the region Monday.
Temperatures may be warm enough for an all rain event, but there is
a small window for a wintry mix Monday morning. The warm front will
remove the shallow wedge by Tuesday. The area will stay in the warm
sector Tuesday and Wednesday with well above normal temperatures
with readings in the 60s.
&&
.AVIATION /02Z THURSDAY THROUGH MONDAY/...
As of 650 PM EST Wednesday...
Generally VFR (intervals MVFR at Blacksburg and Lewisburg)
through about 02z. Thereafter, band of light to moderate rain
now evident in radar imagery in the Tennessee Valley lifts its
way northeast mainly northwest of Danville between 02-07z. This
is well indicated by recent higher-resolution guidance
consensus. Upstream observations in the Nashville TN area and
across a broad part of the Tennessee Valley reflect IFR ceilings
and intervals of mist, though forecast guidance is more
optimistic on ceilings/visbys in this 02-07z period. Will base
TAF forecast in this period heavily on extrapolation versus
recently poorly- verifying guidance, which will thus show a
lower in ceilings to IFR-MVFR levels with MVFR mist and light
rain.
Forecast confidence beyond 07z is low, as behind this initial
wave of rain across the western Ohio/Mississippi Valley is a
large area of MVFR-IFR ceilings with mist at times. Maintained
IFR-MVFR ceilings through 12z, though it`s possible in the 06z
TAF issuance that a greater coverage of mist may be needed if
forthcoming guidance supports ongoing observations behind the
rain shield. Have kept ceilings generally VFR- MVFR for
tomorrow, with MVFR-IFR at Bluefield, Lewisburg...and Danville
with stratus returning northeast from the Carolinas. Wouldn`t
rule out off- and-on showers but timing of these is of low-
confidence.
Winds begin light south/southwest 3-8kts, but speeds trend up
into the day to around 6-12 kts. Southwest low-level jet of
35-40 kts will introduce pockets of low-level wind shear after
06z.
Medium confidence on ceilings/visbys through about 07z, low
confidence on ceilings/visbys after 07z. Medium to high
confidence on winds through the 00z TAF period.
Extended Aviation Discussion...
Rather poor aviation conditions expected through the period as a
series of weather systems continues to track across the country.
Southwest flow aloft will prevail across the eastern U.S. as
a high amplitude right of high pressure aloft remains strong.
Numerous periods of widespread sub-VFR conditions expected
through the period. Winds will be quite strong and gusty through
much of this period as well.
&&
.CLIMATE...
As of 300 PM EST Wednesday...
Thursday 02/15/2018
Site MaxT Year HiMin Year
KBLF 72 1990 54 1990
KDAN 76 1990 57 1949
KLYH 77 1989 55 1949
KROA 79 1989 55 2001
KRNK 66 1990 46 1990
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...None.
NC...None.
WV...None.
&&
$$
SYNOPSIS...KK
NEAR TERM...AL/JH/KK
SHORT TERM...RCS
LONG TERM...RCS
AVIATION...AL/KK
CLIMATE...KK