Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/10/17
Area Forecast Discussion
National Weather Service Columbia SC
915 PM EST Thu Mar 9 2017
.SYNOPSIS...
An upper disturbance and frontal boundary will provide a slight
chance of showers late tonight and Friday morning. Drier air
will move back into the region Friday, with breezy conditions
expected. Cooler air will filter into the region Friday night
and Saturday, as high pressure builds into the Mid Atlantic. An
area of low pressure will track across the Gulf Coast and
offshore the Carolinas, and will bring rain across most of the
region Saturday night and Sunday, possibly snow across the
Northern Midlands.
&&
.NEAR TERM /UNTIL 7 AM FRIDAY MORNING/...
A cold front will approach the region from the Ohio Valley
tonight. Moisture and clouds will increase ahead of the front.
Scattered showers may begin to move into the western counties
before sunrise Friday. The latest HRRR begins bringing rain
into the western portion of the forecast area around
10Z, so have slowed down the timing from previous forecast.
Overnight lows will be mainly in the upper 40s to the lower 50s.
&&
.SHORT TERM /7 AM FRIDAY MORNING THROUGH SATURDAY/...
Friday should see the day starting off with a few showers across
the area as a fast moving shortwave pushes through the region.
Any rainfall will be light and short-lived, and dry conditions
will return by late morning. A cold front will be sinking
southward and through the cwa during the day. Winds ahead of the
front generally out of the southwest early in the day, then
shifting more out of the northwest by the afternoon. Wind speeds
behind the front will increase and become rather gusty during
the afternoon. May need a lake wind advisory for Friday
afternoon, but right now conditions expected to remain just
below criteria, so plan on holding off on any issuance for now.
Friday night will see cooler air pushing into the region behind
the front as surface high builds towards the Mid Atlantic. Lows
Friday night cooling down to the upper 30s to lower 40s.
Saturday will remain dry as high pressure continues pushing in
from the north. Temperatures will be closer to normal for this
time of year.
&&
.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
The main cold front will still be south of the region Saturday
night. However, an area of low pressure is expected to develop
along this front along the northeastern Gulf, and push east
northeast late Saturday night into Sunday morning. Moisture will
flow over the top of the cold airmass that is in place across
the area. The track of the surface low still appears to be a
little too far north than what typically would provide
significant snow for most of the Midlands and CSRA. However,
there will still be a threat for a mixture of rain/snow across
the northern third of the cwa late Saturday night/early Sunday
morning. Surface temperatures will be falling into the lower to
middle 30s across the Pee Dee and Catawba regions by Sunday
Morning. Most of the Midlands, and all of the CSRA, are expected
to be in the upper 30s to lower 40s with this event.
Models have the h85 0 Degree line across the N/NE cwa, just
north of the Midlands. Partial thickness schemes support some
snow, or a rain/snow mix, across the northern third of the cwa,
with some accumulating snow possible across portions of
Lancaster and Chesterfield Counties. Other across the Pee
Dee/Catawba/Northern Midlands that remain a rain/snow mix will
see little to no accumulations. Soil temperatures are still warm
and could limit accumulation and lead to quick melting after
precipitation ends. Too far out for high confidence. For now,
will continue to mention in the HWO for those two counties.
Highs on Sunday will struggle to get into the lower 40s across
the northern counties. Elsewhere highs in the 40s are expected.
An additional system will move into the the region Monday
afternoon. Precip on Monday afternoon expected to be all rain as
temperatures Monday afternoon should reach the upper 40s to
middle 50s.
Below normal temperatures will continue into next
week, and because of this, freezing temperatures could continue
to be a concern for multiple nights next week. Precip may
continue overnight Monday into Tuesday morning, and with surface
temperatures across the northern cwa approaching freezing, there
could once again be some frozen precip Tuesday morning across
the north. Confidence this far out is low, and will continue to
monitor how system evolves. Remainder of the forecast period
will be dry and cool.
&&
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
High confidence in VFR conditions through 09z.
High pressure centered over the Gulf of Mexico will weaken across
the area tonight allowing a cold front to cross the TAF sites
in the 12Z-15Z time-frame. Ahead of the front...clouds will
increase after 06Z. Mainly mid and high level clouds with bases
AOB 4000 feet. Light rain showers may affect the TAF sites
around daybreak. VSBY restrictions are not expected. Clearing
skies and increasing gusty northwest winds are forecast by 16Z
behind the front.
LLWS possible 10Z-15Z as a 40 knot low level jet crosses the region.
EXTENDED AVIATION OUTLOOK...Widespread precipitation and
restrictions anticipated Saturday night through Tuesday
due to a low pressure system.
&&
.FIRE WEATHER...
After a quick shot of light rain early Friday morning,
conditions are expected to dry out once again by the afternoon
as a cold front pushes through the region. Relative humidity
values during the afternoon hours will drop in to the middle 20
percent range, with some areas possibly even lower. Winds behind
the front will become gusty. Sustained winds around 15 mph, with
some gusts upwards of 25 mph, will be possible during the
afternoon. Have issued a Fire Danger Statement to handle these
conditions. Will monitor later data and conditions on Friday,
and we can not rule out the need for a Red Flag Warning if
conditions change.
&&
.CAE WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
&&
$$
Area Forecast Discussion
National Weather Service State College PA
1040 PM EST Thu Mar 9 2017
.SYNOPSIS...
A developing area of low pressure will track just to the south
of Pennsylvania tonight and Friday. Much colder air will follow
for the weekend.
&&
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
Regional radars at 0330Z showing a band of snow congealing
along I-80 corridor from northern Ohio into central Pa
associated with intensifying band of fgen forcing ahead of
strengthening shortwave diving across the Grt Lks. Latest RAP
output showing a dual jet structure crossing the area overnight,
with main jet streak passing across Lk Ontario and another
tracking over southern Pa. In between, models indicating a band
of intense frontogenetic forcing sliding across central Pa
overnight. Cross section analysis is also indicating a good
instability signature with a layer of negative saturated
geostrophic EPV located in a layer just above the frontogenesis
around 600mb. This supports the idea of briefly heavy snow as
the band shifts across central and south-central Pa overnight.
Any initial period of rain should be short-lived based on
upstream reports and model soundings, which support a rapid
change to snow. Accumulating snow will overspread much of
central and northern PA late this evening, lasting into Friday
morning. Across the Lower Susq Valley, expect accumulating snow
to hold off until around 08Z-10Z.
We tried to favor the latest HRRR QPF/Snow amounts which show
the best chance of several inches of snow in a wedge from the
western higher elevations eastward through the central ridge-
valley region, with a sharp northern and southern gradient.
There is still a bit of uncertainty with amounts due to warm
ground and initially above freezing sfc temps. This should hold
down accums during the first couple of hours of the snowfall,
especially across far southern and southeastern portions of the
area, where temps will be the mildest the longest.
Max snow totals expected in the 4-6" range across the higher
terrain of central PA along and just south of the I-80 corridor.
However, there will still be enough accum across a large
portion of the state to impact/disrupt peak travel Friday
morning. Road conditions varying from wet/slushy to snow
covered.
&&
.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
Widespread synoptic snow should taper off across the southeast
counties by late morning, as developing surface low pushes off
the Delmarva Peninsula. A potent shortwave will follow quickly
on the heels of the departing sfc low, ushering in colder air
and increasing wind. An associated pocket of steep low-mid-
level lapse rates greater than 7C/KM will slide across central
and northern PA during the peak heating hours Friday, creating
the potential for snow squalls over much of the region. Still
too early to be confident that the low level convergence can
support organizing the squalls into some sort of organized line
that could cause widespread disruptions. Very cold air and gusty
wind will bring some scattered mountain and Lake Effect snow
showers to Northern an Western PA, while just some flurries are
expected near and just to the east of the I-99 corridor.
&&
.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
*Unseasonably cold weather pattern into Mid-March
*Late-season snow risk early next week
Minimum temps Saturday morning will range from the single
digits across the NW Alleghenies to the low-mid teens in the
Central Ridges and Mid-Lower Susquehanna Valley. Gusty winds
will drop wind chill values into the 0 to -10F range.
Additional minor snow accumulation (0.5 to 1.0 inch) is likely
across the Northwest Snowbelt Friday night into Saturday due to
persistent cold NW flow.
Gusty winds and snow showers will fade into the weekend but it
will remain unseasonably cold for this time of year, especially
in the face of a prolonged mild winter pattern. Call it
winter`s revenge? The cold pattern continues next week with
high confidence in below/well-below average temps. Multi model
blend supports daytime highs 20 to 30 degrees below average on
Saturday, when some sites could tie or set new low maximum
temperature records. (See climate section for list of record low
maximum temperatures for select sites).
A storm system is expected to develop off the Mid Atlantic
Coast early next week and bring the potential for late season
snow on the northern edge of the precipitation shield. Stayed
close to consensus blend of operational GFS/ECMWF and NBM/ENENS
MOS with max POPs 65-70% over the southeast 1/4 of the CWA.
Rain/snow ptype issues are possible between I-81 and I-95. FWIW
the 09/12z operational ECMWF trended slower and closer to the
coast vs. the 09/00z run, lagging behind the GFS/CMC while much
closer to the 09/12z GEFS low position at 12z on 3/14.
&&
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
An approaching wave of low pressure will bring a period of
precipitation and reduced conditions - developing this evening
from the NW - which will continue into early Friday.
Expect conditions to deteriorate from west to east with
widespread MVFR/IFR conditions developing during the 03-06Z
timeframe, and continuing into Friday morning.
MVFR/IFR conditions will gradually improve with a developing
gusty NW wind later Friday morning into the afternoon. Higher
elevation terminals of the west will be the slowest to improve.
As winds pick up, there will be a possibility of brief heavier
squalls during the early/mid afternoon which could bring rapid
reductions and a quick burst of snow.
Outlook...
Sat-Sun...Mainly VFR. OCNL MVFR with scattered snow showers NW.
Mon...VFR with lowering conditions during the afternoon with
snow possible.
Tue...MVFR with scattered light snow or snow showers.
&&
.CLIMATE...
Low Maximum Temperature Records for Saturday, March 11th:
MDT27 in 1934
IPT 26 in 1934
AOO26 in 1998
BFD13 in 1969
STC21 in 1992/1969
&&
.CTP WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 9 AM EST Friday for PAZ010>012-
017-018-041-042.
Winter Weather Advisory until 9 AM EST Friday for PAZ019-
024>028-033-045-046-049>053-058.
Winter Weather Advisory from 2 AM to 9 AM EST Friday for
PAZ056-057-059.
&&
$$
SYNOPSIS...La Corte
NEAR TERM...Fitzgerald/La Corte
SHORT TERM...Fitzgerald/La Corte
LONG TERM...Steinbugl
AVIATION...RXR
CLIMATE...
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
952 PM CST Thu Mar 9 2017
.UPDATE...
Have decreased the rainfall chances through the overnight as the
current light to moderate rainfall over the I-10 corridor continues
to decrease in coverage after an active afternoon and evening. Hourly
temperatures and dewpoints have been realigned with latest trends.
Have increased rain and thunderstorm chances for Friday afternoon
with a similar set-up progged by models. New zones have been sent
out as well.
Pockets of heavy rainfall this afternoon and evening in select
locations resulted in local creeks/streams to swell and overtop low
water crossing bridges and roads. PWATs near 1.3 inches combined
with CAPE values near 2000-2500 J/Kg and outflow boundary convergence
to support persistent heavy rainfall in isolated locations. Since
instability has waned these past few hours, the convection has
finally decreased. With all the low-level moisture in place from
rainfall, fog will be quite likely overnight and into early Friday
morning. Fog will clear by mid-morning hours but a near similar set
up to today appears likely again Friday with models hinting at
another sea-breeze convergence boundary moving in the from the
southeast along with another potential boundary from the northeast
from overnight storms in OK and North Texas. Storm activity Friday
afternoon looks to also shift farther west into the Hill Country and
portions of the US HWY 83 corridor per hi-res SPC SSEO model output.
Localized pockets of heavy rainfall and briefly strong storms with
small hail and pockets of 30-50 mph of wind will need to monitored
for closely as moisture and instability will once again be in place.
Have increased rain and thunderstorm chances another 10 percent
tomorrow afternoon.
&&
.PREV DISCUSSION... /ISSUED 616 PM CST Thu Mar 9 2017/
AVIATION...
Scattered showers and thunderstorms will move through the Austin and
San Antonio areas during the next few hours. Don`t expect any storms
to affect flying category, but lightning may be an issue at AUS. Have
left the rest of the forecast alone for now as it looks good.
PREV DISCUSSION... /ISSUED 356 PM CST Thu Mar 9 2017/
SHORT TERM (Tonight through Friday Night)...
Temperatures have warmed up rather nicely into the mid 70s to lower
80s across the region given a few brief breaks in the clouds. These
warm temperatures combined with a moisture surge from the south
helped the cap erode, allowing showers and thunderstorms to develop
mainly along and southeast of Interstate 35 as anticipated though
perhaps an hour or so earlier than expected. Hi-res models including
the HRRR are finally beginning to catch on to a bit more widespread
coverage of these cells, so the coverage of showers and thunderstorms
has been expanded for this afternoon and early evening with POPs
raised an additional 10 percent. CAPE values are a little higher than
expected up to 2500 J/kg over the Coastal Plains where temperatures
warmed up into the lower 80s, but shear remains weak below 15-20
knots. Thus, although these storms may pulse to produce some small
hail and gusty winds to 40-50 mph supported by midlevel lapse rates
of 6-7 deg/C and DCAPE values around 700-1000 J/kg, storms should not
be organized enough to produce more than perhaps one rogue pulse
severe storm (if that). Showers and thunderstorms should end by 8-9
pm if not earlier given the lack of surface forcing or strong upper
level support as the atmosphere stabilizes after sunset. This should
keep rain chances limited to weak showers along and north of the
Escarpment towards daybreak with patchy to widespread fog over most
of the region aside from the Rio Grande Plains after Midnight as
temperatures cool to their dew points in the mid 60s with weak winds.
Fog should lift by mid-morning with low clouds persisting into the
early afternoon hours before breaks in the clouds help temperatures
warm up into the mid 70s to lower 80s similar to today. Convective
coverage should generally be higher than tomorrow as a back door cold
front approaches the region from the northeast and a weak shortwave
moves into the Rio Grande Plains ahead of a much broader longwave
trough axis southwest of Baja California. Considering isolated to
scattered showers should also develop with an afternoon moisture
surge tomorrow as well similar to today, most of the region has been
blanketed with 40-50 percent POPs due to all of these features. The
weak upper level feature over western parts of the CWA interacting
with wherever the surface boundary ends up should continue to support
at least isolated, if not scattered showers and thunderstorms well
into the evening hours before decreasing overnight. The effects of
this weak front and evaporative cooling should allow lows to be a few
degrees cooler in the lower 60s for Friday night.
LONG TERM (Saturday through Thursday)...
The high temperature and convective forecast for Saturday remains a
bit tricky as it is still difficult to tell how strong and how far
south this back door front will get and how much rainfall will be
ongoing Saturday morning. Nevertheless, PVA associated with the broad
upper level trough that will be approaching from our southwest should
at least encourage scattered to widespread showers with at least
isolated to scattered thunderstorms with greater coverage and more
intense rainfall over our southern areas and South Texas. Shear will
begin to increase towards 25-30 knots by Saturday afternoon and
evening as the cold front approaches to help trigger one final round
of more organized showers and thunderstorms into early Sunday, but
severe storms are still not expected. Rainfall amounts through Sunday
morning should average around one inch, though there will be spots
that have a few heavy downpours that allow them to get 2-3 inches
while others may get less than a half inch.
Drier conditions should filter in behind the front on Sunday with
northerly 15-20 mph winds and temperatures only climbing into the
lower to mid 60s (and perhaps lower if GFS MOS trends are to be
believed). A weak reinforcing front associated with a shortwave
moving through the Midwest will help keep northerly winds in place
and temperatures closer to normal before southerly flow returns late
Tuesday into Wednesday with temperatures warming back above normal
with highs in the 70s and lows in the 50s. A weak front associated
with a shortwave digging quickly into Texas may cause a slight chance
of rain next Thursday. Otherwise, drier and slightly warmer than
normal conditions should continue through most of next week with
northwest flow aloft as both the ECMWF and GFS build a ridge behind
this shortwave that becomes centered over Texas by next weekend.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 66 79 63 76 50 / 70 50 40 40 50
Austin Bergstrom Intl Airport 65 79 63 75 50 / 80 50 40 40 50
New Braunfels Muni Airport 66 78 63 75 52 / 80 60 40 40 50
Burnet Muni Airport 63 75 60 73 46 / 20 40 40 40 50
Del Rio Intl Airport 65 80 62 79 56 / 20 50 30 20 40
Georgetown Muni Airport 66 77 61 75 47 / 20 40 40 40 50
Hondo Muni Airport 65 80 63 77 54 / 40 60 40 30 40
San Marcos Muni Airport 64 79 63 75 51 / 80 60 40 40 50
La Grange - Fayette Regional 67 79 64 74 52 / 60 60 40 60 50
San Antonio Intl Airport 66 79 63 75 54 / 60 60 40 40 50
Stinson Muni Airport 67 78 64 75 55 / 60 60 40 40 40
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Mesoscale/Aviation...05
Synoptic/Grids...Allen
Public Service/Data Collection...33
Area Forecast Discussion
National Weather Service Green Bay WI
529 PM CST Thu Mar 9 2017
Updated aviation portion for 00Z TAF issuance
.SHORT TERM...Tonight and Friday
Issued at 234 PM CST Thu Mar 9 2017
The latest rap analysis and satellite/radar imagery show a secondary
cold front dropping south into northern Illinois early this
afternoon. Still have a fairly wide swath of mid-clouds across the
state behind the front, but clearing is slowly working south over
far northern WI and the Lake Superior region. Looking upstream, a
very cold arctic high is building south into the northern Plains,
where temps are barely above zero. As this arctic high continues to
build south, temps and wind chills are the main forecast concerns.
Tonight...A 1048mb arctic high pressure system will be building
southeast across the northern Plains and western Great Lakes through
the night. As northwest winds strengthen, they will usher in a very
cold airmass to 25 below at 850mb over far northern WI. The airmass
will be quite dry too, but should have lake effect snow showers
develop over western Lake Superior that should push into the snow
belt areas of north-central Wisconsin overnight. The dry air should
limit the coverage area, southward extent, and possible accums to
under a half inch. Elsewhere, mid clouds will be departing during
the evening, resulting in mostly clear and cold conditions
overnight. Lows will fall into the lower single digits below zero
across the north. Combined with a brisk northwest wind, wind chills
will likely fall to around 20 below for a couple hours. Will issue
a sps to highlight the very cold wind chills.
Friday...The arctic high will continue to dominant the sensible
weather across the area. Light lake effect snow showers will likely
continue over the far northern WI snow belts through the day.
Elsewhere, should be mostly sunny, breezy, and cold. Temperatures
should range from 15 to 25 degrees below normal for the date.
.LONG TERM...Friday Night Through Thursday
Issued at 234 PM CST Thu Mar 9 2017
North-northwesterly flow will keep below normal temperatures in
place Friday night and through the weekend. Wind chills at night
are expected to dip into the negative teens in the north and
negative single digits towards the Fox Valley around Saturday
morning. A small chance of snow showers will linger on in the far
north through Sunday, but otherwise conditions through the weekend
will be quiet.
The storm system expected for late Sunday night and Monday
continues to be the primary concern for the extended period.
Models vary on the exact track of this system, with the Canadian
spreading snow across the region earlier than the GFS/ECMWF.
Models then agree that snow showers will overspread the region
Monday morning, but the variance in the tracks keep totals
uncertain. The GFS and ECMWF favor a storm track that could bring
in some lake enhancement along the shoreline and parts of east-
central Wisconsin during Monday afternoon. Snow chances are
expected to stick around through the night and into Tuesday
morning before moving out with the upper level trough during the
afternoon. A more quiet period then returns in the middle of next
week as temperatures return closer to normal by Thursday night.
&&
.AVIATION...for 00Z TAF Issuance
Issued at 528 PM CST Thu Mar 9 2017
A swath of mid-level clouds will depart later this evening with
mostly clear skies expected overnight and into Friday. The main
exception will be lake effect clouds and scattered snow showers
north of KRHI. Light northwest winds will increase to 10 to 20
knots overnight and into Friday.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
SHORT TERM.....MPC
LONG TERM......Uhlmann
AVIATION.......Kurimski
Area Forecast Discussion
National Weather Service Greenville-Spartanburg SC
1033 PM EST Thu Mar 9 2017
.SYNOPSIS...
Above-normal temperatures will persist until a cold front crosses
the region on Friday, ushering in a period of below-normal
temperatures that will last through early next week. Meanwhile,
low-pressure over the Deep South will bring precipitation to the
area late Saturday into Sunday. Another cold front is expected to
cross the area on Tuesday dropping temperatures well below normal
again for the second half of the week.
&&
.NEAR TERM /THROUGH FRIDAY/...
As of 1015 PM EST...The main concern with this update is the
upstream convection over western TN attm. A solid westerly 850 mb
jet is advecting moisture under an area of steep mid-level lapse
rates. For example, the 00z OHX sounding was very dry and had no
CAPE. But by 2z, convection started firing around the OHX area, and
sure enough, forecast soundings there show MUCAPE balloon to over
1000 J/kg. Effective shear in the 40-50 kt range seems to be just
about right for an MCS to continue to propagate across central TN
and into northern AL/GA. The high res models seemed to have diverged
a little bit on the evolution of the system. The HRRR has been most
consistent, having the deep convection miss our area to the SW, but
bringing a band of dissipating showers across the entire area after
midnight. The 00z NAM is further north and indicates strong storms
might scrape the Smokies before weakening. I`ve opted to bump up
thunder mentions in the western NC mountains, but still think the
HRRR is probably closest to reality. PoPs look on track per latest
trends.
Another concern will be winds behind the front on Friday. A wind
advisory may be needed for at least the northern NC mountains.
Confidence is still too low to throw one out on this update.
A strong cold front cross the area early Friday morning and will be
aided by a distinct H5 s/w, and along with good mech lift will
instigate -shra across the mtns by 09z. Expect The majority of the
showers to cross the FA aligned with the upper energy rather quickly
through 12z. Not anticipating much precip due to the fast
track...however most locales shud see measurable amounts. A strong
llvl jet will traverse the area early tomorrow as well...with the
higher mtn locales likely reaching adv level winds shortly after
daybreak. Will leave this issuance to the midnight crew as some
uncertainty is had btw the models wrt to H85 jet timing and
coordination with surrounding offices.
Clouds will break-up fairly quickly by mid morning as the cA sfc
high builds in. This will bring early moderate gusts and good dry
air mixing. Sfc td/s may be a little suspect due to the overnight
precip...but it looks like another FDS day or perhaps a RFW
depending on the amount of fuel moisture level recovery. Min temps
will be held about 10-12 degrees above normal tonight with crossing
opaque llvl cloud cover. Max temps tomorrow will be lower than today
due to the airmass mix...however highs will likely reach about 5-7
degrees above normal in good insol and downslope warming.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/...
As of 245 pm EST Thursday: A very active weekend is upcoming as
colder temperatures develop across the region and a possible winter
storm threatens. The first order of business will be posting a
Freeze Watch for active growing areas in the NW NC piedmont and NC
foothills for Friday night.
The main order of business will be the winter weather potential over
the weekend. A mid-level impulse will dive southeast through the
central plains on Saturday and sharpen up over the MS Valley
Saturday night. Meanwhile, a 1048 mb arctic high center pushing
south across Saskatchewan Friday night into Saturday will send very
chilly thicknesses settling southward across our forecast area. The
nose of this sprawling high pressure system will be in place on
Saturday and increasing clouds from the west will keep temperatures
on the chilly side. A developing surface reflection should then move
from the Gulf Coast to the southeast coastline through late weekend.
Ahead of the approaching upper support, a 140 kt upper jetlet
passing north of the region through the Mid-Atlantic area will bring
strong right entrance region upper divergence through our forecast
area. The peak of the deep layer QG forcing and deeper moisture will
cross the area overnight Saturday night into Sunday morning. In
addition, moist low level upglide into the cold airmass will ramp up
Saturday evening and maximize around 09Z Sunday. Model profiles for
the main event are spread into warmer (ECM/Canadian) and cooler
(GFS/NAM) camps. The GEFS and SREF are not especially supportive of
the very cold/wet solutions so uncertainty remains high. The one
point of consistency is that none of the models exhibit any degree
of warm nosing in profiles, and the ptype forecast will be
predicated on how deep the surface based warm layer remains. It
still appears as if the NC/SC border is generally where the
rain/snow line will set up, and any heavier banded precipitation
toward daybreak Sunday could push snow showers briefly southward to
produce light snow accums on otherwise warm ground. All told, it
remains too early for watch products and the HWO mention will
continue.
Weak banded NW flow moisture will continue over the mountains
through late Sunday but with little to no additional accumulations.
Sunday temperatures will remain cool but rise above freezing
throughout to briefly promote some melting in areas affected by snow.
&&
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
As of 315 PM EST Thursday: Guidance in pretty good agreement in the
overall pattern but with some usual detail differences. An upper
trough deepens over the eastern US as a short wave moves from the
northern Rockies to our area by Monday. An upper low closes off over
the Great Lakes and drops into the trough on Tuesday. The ECMWF is
deeper and slower with the upper low than the GFS. This keeps lower
heights and more troughing over our area through Thursday. The GFS
is quicker to return to more of a zonal flow by Thursday. The GEFS
mean is between the operational GFS and the ECMWF. Therefore, have
trended toward the slower and deeper ECMWF.
At the surface, the lead short wave develops a clipper type low to
our west. This low moves toward the area Monday with cyclogenesis
off the Carolina coast. While not a Miller B type low, it looks like
one with cool high pressure nosed in over the area in a cold air
damming like pattern between the 2 lows. Precip should develop over
the area as southerly low level flow and isentropic flow develops
and moisture increases. The GFS is colder than the ECMWF, but both
models show some wintry precip is possible even outside of the
mountains Monday night. Have limited the p-types to rain/snow for
now, but sleet may also develop given the forecast thermal profiles.
The ECMWF is also wetter due to its slower and stronger system, so
accums are still questionable but more likely over the NC mountains
than any other location.
Should be a brief break in the precip outside of the mountains as
the first wave and surface lows move north of the area. However,
precip will linger across the NC mountains in NW flow. Moisture and
the resulting precip could break containment and spread outside of
the mountains late Tuesday or Tuesday night as the upper low moves
across the area. Again, thermal profiles suggest wintry precip
across the NC mountains which may develop outside of the mountains.
Any accums outside of the mountains would be highly questionable.
Dry high pressure builds in Wednesday and remains for Thursday as
the GFS is likely too fast with the next weather system.
Temperatures will be well below normal through the period with some
up and down variation. This will bring a continued threat for frost
and freeze conditions each morning.
&&
.AVIATION /04Z FRIDAY THROUGH TUESDAY/...
At KCLT and elsewhere...Weakening SW winds and increasing cirrus
expected this evening. Then a line of -SHRA will quickly cross the
area in the 10-13z time frame. Conditions expected to stay VFR,
except possibly very brief restrictions within the fast-moving SHRA.
High pressure builds in quickly behind a passing cold front. Winds
will shift from SW to NW and become quite gusty by late morning and
continue thru the AFTN.
Outlook: A passing low pressure system late Saturday thru Sunday
will bring widespread wintry precipitation to the region, especially
across the mountains, likely generating CIG and VSBY restrictions.
Confidence Table...
03-09Z 09-15Z 15-21Z 21-00Z
KCLT High 100% High 100% High 100% High 100%
KGSP High 100% High 88% High 100% High 100%
KAVL High 100% High 88% High 96% High 100%
KHKY High 100% High 100% High 100% High 100%
KGMU High 100% High 88% High 100% High 100%
KAND High 100% High 100% High 100% High 100%
The percentage reflects the number of guidance members agreeing
with the scheduled TAF issuance flight rule category. Complete hourly
experimental aviation forecast consistency tables and ensemble forecasts
are available at the following link:
www.weather.gov/gsp/aviation
&&
.FIRE WEATHER...
Dry high pressure will continue to control our weather this evening
as RH values have dropped into the mid teens region-wide. There will
be some RH recovery and a band of showers is expected to cross the
area early Friday morning. Later Friday...an arctic airmass will
begin to filter in and allow for another day of good dry
mixing...however overnight light precip may keep fuel moisture
levels high in some areas. Winds will also become quite gusty early
on and continue thru the day as a strong arctic high builds in. This
will again create wx conditions warranting a Fire Danger Statement
or perhaps even a Red Flag Warning. The SCFC has already agreed to a
FDS across the SC zones...so some coordination will be needed with
the NC forestry officials on possible fire wx products for Friday.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...None.
NC...Freeze Watch from late Friday night through Saturday morning
for NCZ035>037-056-057-068-069-502-504-506-508.
SC...None.
&&
$$
SYNOPSIS...CDG
NEAR TERM...ARK/SBK
SHORT TERM...HG
LONG TERM...RWH
AVIATION...ARK
FIRE WEATHER...
Area Forecast Discussion
National Weather Service Houston/Galveston TX
913 PM CST Thu Mar 9 2017
.DISCUSSION...
At 6 PM, a weak trough of low pressure extended from about Ponca
City OK to Lubbock. Sfc high pressure was located over the
northern gulf coast. Radar still showed a few weak showers north
of houston and some patchy light rain in Colorado/Jackson
counties. Short term guidance has precipitation ending in an hour
or so but with plenty of 850 mb moisture available (dew pts near
11 C) will keep 20 PoPs in place for the remainder of the night.
Bumped min temps up a few degrees with low clouds beginning to
develop and dew pts in the upper 60s, don`t think temps will fall
into the mid 60s by morning. Water temps have warmed into the
upper 60s today and with dew pts in the upper 60s, not getting
enough of a difference to generate sea fog. Certainly can`t rule
it out, but it is looking less likely.
A series of weak upper level disturbances will move across SE TX
Friday and Saturday bringing the region a good chance of showers
and thunderstorms. A weak boundary will move into the north on
Friday and may serve as an additional focus for shra/tsra. The 18z
run of the Texas Tech WRF shows good potential for rain on
Saturday and this matches up well with the wetter Canadian and
ECMWF. GFS and NAM continue to advertise much drier solutions.
The ECMWF jet structure places SE TX in a weak jet couplet while
the GFS keeps SE TX in a less dynamic upper pattern. 43
&&
.PREV DISCUSSION... /ISSUED 555 PM CST Thu Mar 9 2017/
AVIATION...
A series of weak upper level shortwave troughs will move over the
area during the next 24 to 30 hours. Saturday evening a cold front
will approach KCLL and KUTS from the north. The main items of
concern for the aviation interests include developing MVFR, IFR,
and LIFR conditions later this evening and the possibility of sea
fog developing along the coast and over Galveston Bay.
The isolated to scattered showers and thunderstorms will diminish
early this evening. Kept in the possibility through 02Z. Best
chances for thunder will be near or at KCLL and KUTS.
The model forecast soundings and model guidance both forecast
lowering conditions to IFR to LIFR between 04Z and 08Z over the
inland sites. Sea fog chances look less than 24 hours ago given
the dewpoints over the continental shelf waters were near the
water temperatures. Some warm air and moist air advection was
occurring which should lead to slight higher moisture values later
tonight. The model soundings near the coast also indicate the
possibility of sea fog. Will wait to see if the fog develops
before going with lower visibility values.
As did earlier today, the low ceilings and any fog should lift
between 15Z and 18Z. Models are showing the possibility of showers
Friday afternoon.
40
PREV DISCUSSION... /ISSUED 408 PM CST Thu Mar 9 2017/
DISCUSSION...
High temperatures today still expected to reach into the late
70s late this afternoon. Current radar observations show scattered
showers and an isolated thunderstorm or two in the northwestern
section of the CWA. Showers and an isolated thunderstorm will
still be possible late this afternoon and into the early evening.
Short term guidance, such as the HRRR and RAP are both showing the
showers and thunderstorms ending around 02Z or 8PM CT tonight.
High pressure located over the eastern seaboard scoots to the
southwest Thursday night into Friday, pushing over the Gulf of
Mexico. This high pressure system hangs tight through most of the
afternoon Friday. Late Friday afternoon, a backdoor front pushes in
from the northwest. As this front moves into SE TX, it`s orientation
should be perpendicular to the coast. Therefore, not much
convergence or lift will be provided due to the direction from which
the front pushes into the region. Although there will be a lack of
lift from the backdoor front, forecast soundings are showing
fairly unstable conditions. PWs are also fairly high for Friday
afternoon, with values around 1.5 inches. The instability in the
atmospheric profile, along with daytime heating should provide
decent shower and thunderstorm development. PoPs ranging Friday
between 50 to 70% out in front of the backdoor front. Winds will
become more easterly behind this passage.
Southeasterly onshore flow returns early Saturday, out ahead of
the next cold front pushing through the region late Saturday, into
early Sunday. Expecting showers and thunderstorms Saturday
afternoon into Sunday night, out ahead of this cold front. High
temperatures should dip into the low 60s on Sunday, which will be
the coolest day this weekend. Strong north northeasterly winds
behind the front will prevail through late Tuesday. High
temperatures will be back into the 70s by Monday. Winds should
slowly shift out of the southeast by Wednesday morning and partly
cloudy skies will return to the forecast.
Hathaway
MARINE...
Sea fog has mixed out and visibility 3 to 5 miles but late this
afternoon and evening expect it to lower and another dense fog
advisory may be needed for the bays and nearshore waters.
Winds and seas remaining on the low side tonight and Friday with
winds increasing late and Saturday. Winds will be highly dependent
on the formation of surface low near the Coastal Bend and tracking
near the coast or offshore as the lead s/w rotates across
Saturday/Saturday night. Low confidence on winds late Saturday.
Strong storms possible with the passage of the s/w Saturday/Saturday
night.
45
&&
.PRELIMINARY POINT TEMPS/POPS...
College Station (CLL) 67 75 62 72 48 / 20 60 60 70 50
Houston (IAH) 67 78 61 72 53 / 20 70 30 60 40
Galveston (GLS) 67 70 64 71 57 / 20 40 30 60 50
&&
.HGX WATCHES/WARNINGS/ADVISORIES...
TX...NONE.
GM...NONE.
&&
$$
Discussion...43
Area Forecast Discussion
National Weather Service Lincoln IL
848 PM CST Thu Mar 9 2017
.UPDATE...
Issued at 848 PM CST Thu Mar 9 2017
Cold front continues to sag southward this evening, with 02z/8pm
analysis showing it along the I-64 corridor. Most of the
precipitation associated with this boundary is well to the south
across the Ozarks into western Kentucky/Tennessee where widespread
thunderstorms are occurring. Further north into the cool sector, a
narrow band of showers and isolated thunderstorms developed near
I-72 earlier this evening. This precipitation has since nearly
completely dissipated, with only a few lingering showers across
east-central Illinois near the Indiana border. Based on latest
trends and HRRR forecast, have dropped PoPs everywhere except
across east-central and southeast Illinois where a few showers
will continue to be possible through midnight. After that, am
expecting clearing skies and chilly temps for the remainder of the
night with lows ranging from the lower 20s far northwest around
Galesburg to the middle 30s far southeast around Lawrenceville.
&&
.SHORT TERM...(This evening through Friday)
ISSUED AT 234 PM CST Thu Mar 9 2017
A quasi-stationary front south of I-72 near a Taylorville to Paris
line at mid afternoon and extended to a weak 1012 mb surface low
pressure over southeast KS. Temps at mid afternoon contrast from 49
at Lacon to 72F in Flora. The front begin to push southward as a
cold front across southeast IL late this afternoon and early
evening, as weak surface low pressure tracks eastward into southern
IL by mid evening. Have chances of rain showers mainly south of I-72
during early/mid evening with isolated rain showers as far north as
I-72. MUCAPES peak from 200-400 J/kg in southern six counties by
early evening and will continue mention of isolated thunderstorms in
southeast IL especially during 1st half of this evening. Mid and
high clouds have increased over central IL by mid afternoon and
clouds will increase over southeast IL during next few hours. Lows
overnight will range from the lower 20s nw of the IL river, to the
lower 30s in southeast IL from I-70 southeast.
Strong 1048 mb Canadian high pressure over northern parts of Alberta
and Saskatchewan and ridging into the upper Midwest, will continue
to ridge/build into the Midwest through Friday and bring dry and
colder air into the region overnight and Friday. Clouds will be
increasing already from the nw by Friday afternoon ahead of next wx
system. Much colder highs Friday range from mid 30s from I-74 north
and lower 40s in southeast IL, which is a good 10 degrees below
normal.
.LONG TERM...(Friday night through Thursday)
ISSUED AT 234 PM CST Thu Mar 9 2017
Main forecast issues revolve around the fact that winter is deciding
it finally wants to show up. A couple periods of snowy conditions,
as well as temperatures below normal, are the highlights.
Friday night/Saturday storm system continues to track primarily
southwest of our forecast area. Several of the models are holding
back a bit on the arrival aside from the ECMWF, mainly focusing on
Saturday. Given the warm ground temperatures (50-55 degrees at 4
inch depth) and the higher sun angle these days, this will work
against any substantial accumulations. Currently appears the main
focus will be in west central into southern Illinois, with potential
for an inch as far east as Jacksonville and Flora, with generally
minor accumulations elsewhere. Will linger some light snow across
the far south into early Saturday evening, but think most of the
precipitation will be out of the area by late afternoon.
As a shortwave drops southeast into Montana early Sunday morning, it
will aid in the development of a surface system over the northern
Rockies, with the longer range models centering it over western
Missouri or Iowa by Monday morning. As a warm front extends eastward
across Illinois, precipitation will be most widespread north of this
boundary, so the ultimate positioning will be key. Snow again looks
to be the main issue, at least into Monday morning, with a
transition to rain or a mix from south to north. Too early to pin
down accumulations, but with a more extended period of colder air in
place, this could help prime the ground to let the snow stick better
than the weekend system. Most of the lingering snow should move out
Monday evening, but as the storm system intensifies off the mid-
Atlantic coast, the circulation could bring some snow showers off
Lake Michigan into eastern Illinois through Tuesday. For now, will
only carry slight chance PoP`s to address the latter scenario.
Other complication is with the temperatures. Upper long wave trough
will dig across the Mississippi Valley early next week, as an upper
low closes off over the Midwest. 850 mb temperatures fall to -14C on
Tuesday. Blended model guidance appears to be too warm, likely due
to the bias corrections that were absorbed during the abnormally
warm weather over the last few weeks. Have undercut the numerical
guidance by 3-5 degrees for Monday through Wednesday, with highs
mainly in the 30s.
Nighttime temperatures are more problematic. Normal lows are close
to 30 degrees these days, and lows through the period will generally
be in the upper teens to mid 20s. Normally this wouldn`t be much of
an impact, but spring growth is starting to take off much earlier
than normal due to the warm weather the last few weeks. Checks with
horticultural interests in southeast Illinois indicate that
ornamental and flowering trees (such as peaches) are already
blooming, and are very susceptible to freezing conditions. As such,
a Freeze Warning is being issued for Friday night through Sunday
morning for areas south of I-70, in conjunction with the NWS offices
to the west and south. Impacts north of there are not as significant
yet, so no headlines will be used there at this time. There likely
will need to be additional headlines next week, as the lows don`t
rise above freezing through midweek, but daytime temperatures in the
30s will negate the need for a single warning running the entire
forecast period.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 537 PM CST Thu Mar 9 2017
VFR conditions will prevail through the entire 00z TAF period.
23z/5pm radar imagery shows a narrow band of showers developing
near the I-72 corridor well behind a cold front that is dropping
into southern Illinois. Most high-res models do not adequately
pick up on this band: however, based on radar loops, have decided
to include a 2-3 hour period of -SHRA with ceilings around 6000ft
at KSPI, KDEC, and KCMI through 03-04z. Once these showers push
off the E/SE, overcast but dry conditions will persist for the
remainder of the evening. Satellite imagery shows partial clearing
upstream across Missouri, and am expecting that clearing to work
into central Illinois overnight into Friday morning. Winds will
initially be from the NE this evening, then will gradually back to
the NW later tonight into Friday.
&&
.ILX WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from 6 PM CST Friday to noon CDT Sunday for
ILZ066>068-071>073.
&&
$$
UPDATE...Barnes
SHORT TERM...07
LONG TERM...Geelhart
AVIATION...Barnes
AREA FORECAST DISCUSSION
National Weather Service Jackson KY
1027 PM EST Thu Mar 9 2017
.UPDATE...
Issued at 1027 PM EST THU MAR 9 2017
WSR-88D radar is showing an MCV is moving into portions of western
KY and TN this hour. Some showers and isolated storms are moving
east toward the southern portions of the CWA this hour. Given the
trends did opt to bring showers into the far south a bit earlier
than before. Otherwise feel like the forecast grids remain in good
shape this update. Also updated temps/dews/winds with latest obs
and trends.
UPDATE Issued at 710 PM EST THU MAR 9 2017
Evening surface analysis suggests the cold front resides across
the Ohio Valley and stretches back to into eastern Kansas near
the surface low. This surface low is expected to eject east across
Kentucky tonight and swing the cold front across the region toward
dawn. Overall latest guidance and analysis would lead to little
change needed in current forecast grids. However will update
temps/dews/winds with latest obs and trends.
&&
.SHORT TERM...(This evening through Friday night)
Issued at 317 PM EST THU MAR 9 2017
Water vapor imagery this afternoon show significant dry air over
the area. A shortwave is crossing Missouri has triggered some deep
convection over the central portion of the state. A surface cold
front is then dropping southward across Illinois and northern
Indiana. The convection out to the west will work east southeast
through the evening and overnight hours. Given the convection has
already formed, short term hi-res guidance should do fairly well
with this activity as it spreads our way. In fact, HRRR has been
fairly consistent with this convection spreading across our
far southern Kentucky counties late tonight. For this reason, have
opted to toss in some small thunder chances for areas south of the
Hal Rogers Parkway. Showers should increase ahead of the
approaching cold front as well overnight as it draws moisture
north from the shortwave passing across the area. This will yield
widespread showers across the area late tonight. Best rainfall
will probably be in the south with any convection. As the front
exits early Friday morning, we should dry out nicely and in fact
should see some clearing by late morning or afternoon. Cooler
weather settling in behind the front will keep temperatures much
cooler generally in the 40s. Dewpoints will drop off sharply and
we may still see some lower RH values Friday afternoon, but with
the rain, fuels should be too wet for much of a fire weather
concern.
By tomorrow night, a cold night is setting up as temperatures
could plummet early before clouds begin to move in ahead of our
next system late at night. Low temperatures in the upper teens to
low 20s are likely. After talking with the UK Ag weather center
today, we have decided to start issuing freeze headlines as fruit
trees, especially peaches could be impacted by the temperatures we
are expected this weekend.
.LONG TERM...(Saturday through Thursday)
Issued at 405 PM EST THU MAR 9 2017
The overriding theme during the period will be below normal
temperatures, and the potential for winter weather from two
difference systems.
A cold air mass will already be in place as the period starts. A
mid/upper level wave will move in from the northwest and moisture
will override a front well to our south. The result should be snow
developing, but the big questions still remaining are: 1) where
will the northern edge be, and 2) how much will fall. Models are
still not in agreement, but the overall trend in models is still
for the system to track further south. Taking this into account,
the Thursday afternoon forecast issuance contains no precip at the
northern edge of the JKL forecast area. The heaviest snow is at
our southern/southeastern border with near 3 inches. However,
models trends will still need to be monitored for potential
changes.
A brief break in inclement weather occurs Sunday into Monday,
before system number two shows up. A deep mid/upper level trough
will dive into the eastern CONUS. An associated surface low should
sweep by near of just north of the JKL forecast area, with a burst
of cold air arriving in its wake. We should see some showers
develop, initially as rain on Monday, but transitioning to snow as
colder air arrives. Tuesday still looks like a blustery day with
scattered to numerous snow showers before precip begins to taper
off. Temperatures in this air mass may very well fall into the
teens Tuesday night and Wednesday night, spelling bad news for
vegetation which got a jump start with early season warm weather.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
ISSUED AT 650 PM EST THU MAR 9 2017
VFR conditions are the story to begin the period, but this will
not stick as we move into the overnight. A cold front and
developing surface low is expected to move across eastern KY late
tonight into Friday morning. This front will bring showers into
the region after 06Z. This will also lead to low MVFR to perhaps
brief period of IFR CIGs by 10Z to 12Z. Right now confidence is
low on actually seeing IFR and window would be quite short. VFR
conditions will return late morning to early afternoon. Winds will
shift from 220 tonight to 320/350 toward dawn behind the front,
and also winds could be gusty through the day Friday at 15 to 20
knots.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from 11 PM Friday to 10 AM EST Saturday for
KYZ044-050>052-058>060-068-069-079-080-083>088-104-106>120.
&&
$$
UPDATE...DJ
SHORT TERM...KAS
LONG TERM...HAL
AVIATION...DJ
Area Forecast Discussion
National Weather Service Louisville KY
942 PM EST Thu Mar 9 2017
.Mesoscale Update...
Issued at 940 PM EST Thu Mar 9 2017
Storms are making it into our southern KY counties now, and we have
elected to leave our counties out of Severe Thunderstorm Watch #74,
in coordination with SPC. A wing of warm advection elevated storms
is lifting into the area, and they have a history of producing
marginally severe hail due to low freezing levels. However, the lack
of any surface or ML CAPE, will limit the wind/tor threat so expect
problems to be minimal. Strong storm threat will also be shortlived
as the main surge will be ESE with a bowing segment across western
KY/TN. This should stop the northward progression of the meso-warm
front over our southern tier or two of counties in the next few
hours.
Have thunder mention in the grids/TAFs to cover the threat, along
with a graphical nowcast on web/social media to mention best chance
for storm coverage and associated threats.
Issued at 807 PM EST Thu Mar 9 2017
A cold front is expected to slowly sink along the Ohio River over
the next few hours. Meanwhile, a convective complex will slide from
southern MO across western KY and into TN. The bulk of the activity
should miss to our SW, however a few showers and storms are possible
in the warm advection regime ahead of the main complex. In fact,
chances for isolated to widely scattered storm coverage will
increase over the next 1 to 2 hours near the Bowling Green region.
Not expecting any severe at this time, however will have to watch
our far south if a stronger storm is able to hold together and
present a brief hail threat. Will continue to monitor latest
convective trends, radar, and hourly mesoanalysis.
Further north, expect mainly just rain with perhaps an embedded
rumble of thunder by late evening.
&&
.Short Term...(This evening through Friday night)
Issued at 255 PM EST Thu Mar 9 2017
Big changes in the weather pattern are on the way. A cold front that
will impact us tonight is sitting north of the CWA, with
temperatures in the 40s and 50s across the Upper Ohio River Valley.
Currently in our CWA, temperatures are in the 70s and winds are
breezy out of the southwest. Satellite reveals mostly clear skies
with only a few high cirrus moving in from the west.
The cold front will move through the region this evening and put an
end to the warm temperatures we`ve experienced recently. Showers and
thunderstorms will be possible along and ahead of the cold front as
it sweeps in from the north around midnight. Another round of
thunderstorms that are already ongoing in KS/MO could end up
evolving into a large squall line and clipping southwestern portions
of the CWA just ahead of the cold front (between 03-06z). Most
models keep MUCAPE under 500 J/Kg for duration of event, with the
exception of the RAP and NAM which push MUCAPE as high as 700-
800J/Kg in southwestern portions of the CWA. Given strong deep layer
shear (50-60kts of 0-6km shear), can`t rule out some of the storms
producing gusty winds and small hail, and perhaps even an isolated
low-end severe report. The greatest chance for any strong or
isolated severe storm will be in southwestern portions of the CWA,
and this aligns well with latest SPC outlook at the time of writing
this.
Friday will be cool and breezy as a very strong high pressure system
begins to build into the region and advect cold, Canadian air
southward. Should see sunshine for most of the day Friday until the
afternoon when high to mid level clouds start building in ahead of
the next system.
Clouds will continue to increase in coverage Friday night but should
remain dry as low levels of the atmosphere show quite a bit of dry
air. Overnight temperatures will be quite chilly, with low to mid
20s expected in most locations. Temperatures this cold will have an
impact on peach and other fruit trees that are currently in bloom,
as well as strawberries and winter wheat. After coordinating with at
the UK Ag Weather and surrounding WFOs, we have decided to go
forward with a freeze warning for all of central Kentucky given the
aforementioned impacts to trees and crops.
.Long Term...(Saturday through Thursday)
Issued at 300 PM EST Thu Mar 9 2017
...Accumulating Snow Possible Saturday and Saturday Night Across
South Central Kentucky...
Attention turns to an incoming storm system for Saturday that will
bring snow to the region. Details of this system are expanded on
down below.
Track and Timing...
Confidence is moderate in track and timing. The operational 12z
GFS/GEFS/ECMWF/Canadian are fairly consistent and keep majority of
precipitation across southern Kentucky and northern Tennessee. The
NAM is an outlier and has the precipitation shield much farther
north toward southern Indiana. Will lean more toward a
GFS/GEFS/ECMWF/Canadian forecast blend and throw out the NAM for now.
Precipitation Type...
Confidence is high in the precipitation type. Model soundings show
temperature profiles that are below freezing for the entire column
for the duration of the event once the precipitation starts reaching
the ground across southern Indiana and central Kentucky. Even
locations near the Tennessee border look to be all snow.
Precipitation Timing...
Confidence is moderate in the timing of this event. Model soundings
reveal very dry air in the 900mb-800mb layer of the atmosphere that
the precipitation will have to overcome before it reaches the
surface. This will ultimately have an impact on when the snow will
start, but current thinking is that western portions of the CWA
could see it start as early as 15z-17z, before it spreads eastward
by the afternoon. Should see snow end west to east, with snow
tapering off in western portions of the CWA by Saturday evening (03z-
06z Sunday), and eastern portions of the CWA after midnight (09-12z).
Potential Accumulations...
Confidence is moderate regarding snowfall accumulations. At this
time, it appears that southern Kentucky (south of a line from
Morgantown, KY to Liberty, KY) have the best chance to a wet 1 to 2
inches of snow, with isolated higher amounts near the Tennessee
border. North of that line toward north-central Kentucky and
southern Indiana, snowfall and accumulations will be very limited,
maybe a half inch to inch at most. Warm ground temperatures will be
the main limiting factor for a big snow event for this region,
despite having temperature profiles aloft below freezing and
saturation/lift in the DGZ. Changes in storm track will also
influence where the heaviest amounts fall, which have been fairly
consistent in the past day or so, but were all over the place just a
few days ago.
After collaborating with neighboring offices, have decided to keep
an SPS out for the potential snow Saturday and Saturday night. As
confidence increases and the finer details begin to reveal
themselves, winter weather headlines may be needed in the near
future.
By 12z Sunday, the system will be pushing out to the eastern US.
Might have a few lingering clouds early in the morning, but should
see the sunshine return by late morning. The weather pattern beyond
Sunday remains cold and unsettled, with additional chances for
precipitation through early next week. Thermal profiles would
support some snow during that period, but there are quite a few
differences in long range model output to get into any detail on
amounts and timing. For now will take a blended approach of the
models.
&&
.Aviation...(00Z TAF Issuance)
Issued at 633 PM EST Thu Mar 9 2017
A cold front currently sits across southern MO/IL/IN/OH and will
works southward overnight. Ahead of this boundary, a convective
complex is moving ESE across southern MO. This complex will threaten
mainly BWG later this evening, however all TAF sites have a shot at
some rain.
Best chance for a shower and storm at BWG will be 1030 PM CST to 100
AM CST. Brief MVFR ceiling/vis is possible along with gusty winds.
Best chance for a shower at SDF will be 1030 PM to 1 AM EST where
brief MVFR vis is possible. Best chance for a shower at LEX will be
from Midnight to 2 AM EST where brief MVFR vis is possible.
Winds quickly shift to a NW and then NNW direction and gust up
around 20-25 mph behind the front overnight. Some lower ceilings
near the MVFR/VFR threshold are also possible, before clearing
toward dawn. A steady, and even gusty NW wind will persist on
Friday.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
IN...None.
KY...Freeze Warning from 11 PM EST /10 PM CST/ Friday to 9 AM EST /8
AM CST/ Saturday for KYZ023>043-045>049-053>057-061>067-
070>078-081-082.
&&
$$
Mesoscale Update...BJS
Short Term...DM
Long Term...DM
Aviation...BJS
Area Forecast Discussion...UPDATED
National Weather Service Mobile AL
648 PM CST Thu Mar 9 2017
.DISCUSSION...See updated information for land areas and aviation
discussion below.
&&
.UPDATE...Did a quick update to the current zone forecast mainly
to increase rain chances a tad for this evening occurring mostly
over the western half of the forecast area or generally along and
west of a line stretching from Camden Alabama to Wiggins
Mississippi. Latest radar trends show isolated to scattered
thunderstorms over the lower part of Mississippi stretching south
over interior sections of Louisiana this evening moving east at
25 to 30 mph. Although most of the model guidance does show a
weakening trend mainly for this evening have opted to extend the
chance of rain a little further east. Better development is still
expected after midnight tonight as better mid level forcing well
to the nw early this evening continues to approach the central
gulf coast overnight and early Fri morning. 32/ee
&&
.AVIATION...
06Z issuance...MVFR to IFR cigs and visibilities later this
evening and overnight continuing through the day on fri. The
lower ceilings and visibilities will be in and around isolated to
scattered showers and thunderstorms moving in from the west and
north overnight continuing through much of the day on Fri. Patchy
fog and low status will also develop late this evening and
overnight continuing through mid morning Fri possibly leading to
brief periods of LIFR cigs and visibilities mostly between 10.09z
and 10.14z. Winds will be south to southwest at 5 to 10 knots
early this evening gradually shifting west then northwest
overnight through fri afternoon. 32/ee
&&
.PREV DISCUSSION... /issued 404 PM CST Thu Mar 9 2017/
NEAR TERM /Now Through Friday/...Weather maps show a rather
broad west northwest flow aloft extending from the southern high
plains into the southeast. At the surface, a quasi-stationary
surface front was draped across the central US where forecasters
are beginning to see convection forming over Missouri. Along the
coast, high pressure ridge was positioned from GA into the Gulf.
Around the western periphery of the high, surface based moisture
has been steadily increasing with dewpoints lifting up into the
mid to upper 50s over the western zones. Going into tonight, the
mean high level flow becomes more northwesterly in direction and
favors the southeastward movement of the storms out of Missouri
and into the Mid-South. There are indications in the high
resolution HRRR model guidance that these storms may make it into
the interior of the local area shortly before daybreak Friday
morning ahead of a front that pushes southward over the deep
south. There is also potential for patchy nighttime fog
development with the latest short range ensembles and HRRR
focusing this along the southern half of the area generally south
of US Hwy 84. A chance of showers and storms follow for Friday
morning. Chances decrease by afternoon over the interior as front
clears those areas. Overnight lows look to be mild, ranging from
the upper 50s interior to lower half of the 60s coast. Daytime
highs on Friday, unseasonably warm with numbers ranging from 75
to 80. /10
SHORT TERM /Friday night Through Sunday night/...A drier northwest
flow pattern aloft will set up across the forecast area Friday
night, while a light northeasterly surface flow pattern is expected
with cool surface high pressure ridging from the Tennessee Valley
to the central Gulf Coast region. With precipitable water values
generally averaging less than 0.5", we will maintain a dry
forecast Friday night, with colder overnight lows in the lower to
mid 40s expected over interior portions of the forecast area with
readings in the upper 40s to lower 50s near the coast and beaches.
The dry/low precipitable water airmass will hold in place across
central and eastern portions of the forecast area through Saturday
morning, before deep layer moisture gradually increases from west
to east across much of the forecast area by Saturday afternoon in
response to an approaching shortwave trough embedded within zonal
mid level flow. Deeper moisture and stronger lift will remain
focused mostly to the west of our forecast area during the day
Saturday, but expect at least isolated to scattered rain showers
and possibly isolated thunderstorms could develop over central and
western portions of the region by Saturday afternoon. We have
generally maintained a 30-40% chance of convection over central
and western portions of the CWFA by Saturday afternoon, with
10-20% coverage at best over the east. Highs Saturday should range
from the upper 60s to lower 70s.
The aforementioned shortwave trough axis will continue to
translate eastward across the central Gulf Coast region Saturday
night into Sunday morning, while the ECMWF and CMC operational
guidance both indicate a deepening surface low over the northwest
and north central Gulf of Mexico Saturday night into Sunday. The
GFS continues to show a weak inverted trough much farther south
during this time frame. Guidance members also show surface ridging
extending southward into the north central Gulf of Mexico this
weekend, with a reinforcement of colder air arriving late Saturday
night into Sunday across our forecast area. Confidence remains
high that rain showers will spread across the region Saturday
night as the shortwave trough and reinforcing cold front spreads
over the region. We will also keep POPs in the likely (60-70%)
range over southern areas into Sunday morning as additional
precipitation spreads overhead with the potential surface low
passing south of our area. Given the cool and relatively stable
airmass over the region, the overall thunder potential looks
relatively low late Saturday night and especially Sunday, so will
keep mention as mostly rain showers. Rain chances should decrease
Sunday afternoon into Sunday night as shortwave troughiness moves
eastward. Lows Saturday night range in the 40s to around 50 over
the interior to the lower to mid 50s near the coast. Highs Sunday
should range in the mid 50s inland to lower 60s coast. Lows Sunday
night will be colder, ranging from 40-45 over the interior to
around 50 near the coast. /21
LONG TERM /Monday Through Thursday/...A cool and dry weather
pattern is expected through the long term portion of the forecast
underneath a general northwest flow pattern aloft. Highs early in
the week generally look to range in the lower to mid 60s. A
reinforcing cold front will bring cooler temperatures late Tuesday
and Wednesday. Will need to watch for lows near freezing over the
interior Tuesday night - the current forecast has readings in the
lower to mid 30s over interior areas, and upper 30s to lower 40s
near the coast. Highs Wednesday should be cooler in the upper 50s
to lower 60s. Temperatures should modify a few degrees Wednesday
night into Thursday. /21
MARINE...A series of fronts make passage over the coastal
waters. The first comes thru on Friday afternoon bringing an
increased offshore flow Friday night. The next frontal passage
looks to occur on Sunday bringing moderate to strong offshore flow
in its wake. A better chance of showers and storms looks to
accompany this front. There is also some potential for a frontal
wave of low pressure to develop over the upper Texas coast late
Saturday night and track eastward across the northern Gulf, off
the Louisiana coast on Sunday. The result would be a moderate to
strong northeast flow and building seas late in the weekend.
Something we will be watching. /10
&&
.MOB WATCHES/WARNINGS/ADVISORIES...
AL...None.
FL...None.
MS...None.
GM...None.
&&
$$
This product is also available on the web at:
http://weather.gov/mob
Area Forecast Discussion...UPDATED
National Weather Service Morristown TN
938 PM EST Thu Mar 9 2017
.DISCUSSION...
MCS over far NW Tennessee will continue to move ESE across Middle
Tennessee and eventually into the Plateau and Central and Southern
Valleys between 06-08z per the latest runs of the HRRR and RUC.
Instability is extremely limited and with essentially no CAPE
east of I-75. A strengthening 60 kt 850 mb jet between 06-09z per
the NAM will help keep this line together into the region, with
strong to marginally severe wind gusts possible, locally in the
50-60 mph range -- and plenty of lightning. This activity will
wane as it moves toward the mountains before exiting the area
early Friday morning. Strong gradient winds are also expected
ahead of the line along the Great Smoky Mountains where a Wind
Advisory is in effect overnight into Friday morning.
&&
.PRELIMINARY POINT TEMPS/POPS...
Chattanooga Airport, TN 53 63 34 53 / 80 10 0 30
Knoxville McGhee Tyson Airport, TN 49 56 28 43 / 80 20 0 30
Oak Ridge, TN 49 58 28 44 / 80 20 0 40
Tri Cities Airport, TN 43 53 23 37 / 80 40 0 50
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...None.
TN...Wind Advisory until 10 AM EST Friday for Blount Smoky Mountains-
Cocke Smoky Mountains-Sevier Smoky Mountains.
VA...None.
&&
$$
AMP
Area Forecast Discussion
National Weather Service Norman OK
846 PM CST Thu Mar 9 2017
.UPDATE...
Reoriented and increased precipitation chances.
&&
.DISCUSSION...
The HRRR and RAP have been showing a consistent signal of the
convective development west along the front as it moves south, and
the satellite and radar trends are beginning to show this
development over the last half hour into Lincoln County. The
forecast was updated around 8 PM to reorient and increase
precipitation chances tonight, especially in the southeast. We
will continue to monitor the convective trends this evening.
&&
.PREV DISCUSSION... /issued 510 PM CST Thu Mar 9 2017/
AVIATION...
A few showers are possible this evening near the I-44 corridor in
central Oklahoma, however chances remain too low to mention in TAFs.
Otherwise, a cold front will drop south through the area this
evening/overnight with gusty northeast winds. Winds expected to
diminish Friday afternoon. Low level moisture may pool enough ahead
of the cold front near the Red River for a period of MFVR ceilings
at SPS Friday morning.
30
PREV DISCUSSION... /ISSUED 310 PM CST Thu Mar 9 2017/
DISCUSSION...
A cold front will move southwest across Oklahoma and north Texas
tonight, shifting winds to the northeast, and bringing somewhat
cooler weather into the region. As it passes through Oklahoma, it
may set off a few thunderstorms, mainly east of I-44. In addition,
a few elevated showers/thunderstorms will occur late this
afternoon in our Texas counties, and perhaps neighboring counties
in southwest/south-central Oklahoma. These will be mainly
isolated. Instability will be strong enough to support
marginally-severe storms in any evening convection that develops,
but wind profiles will greatly limit supercell potential.
Rain chances will increase substantially on Saturday as moisture,
isentropic lift, and an upper-level wave all converge on Oklahoma
and vicinity. Some elevated instability may support a few
thunderstorms over southern Oklahoma and north Texas.
Northwest flow aloft will result in occasional frontal passages,
but generally dry conditions (little or no rain) for the rest of
the forecast period.
&&
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 44 59 45 52 / 20 0 20 70
Hobart OK 45 59 48 61 / 10 0 30 50
Wichita Falls TX 52 63 53 69 / 20 10 20 60
Gage OK 34 57 42 58 / 0 0 20 40
Ponca City OK 40 55 39 44 / 10 0 40 90
Durant OK 52 67 48 59 / 30 20 30 60
&&
.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&
$$
Area Forecast Discussion
National Weather Service Pueblo CO
357 PM MST Thu Mar 9 2017
.SHORT TERM...(This evening through Saturday)
Issued at 357 PM MST Thu Mar 9 2017
Tonight through Saturday...
A cold front will move southward this evening into southeast CO,
bringing northerly winds that may be gusty for a little while. Late
tonight, much of the southeast plains will see the winds then become
easterly. Toward morning the NAM is showing high low level RH
values over the far southeast plains, indicating the possibility of
low stratus in these areas. The HRRR and GFS are not showing the
low levels being as moist as the NAM. The NAM also holds on to the
increased low level mstr thru a good share of the day ovr portions
of the far sern plains, so there could be clouds over those areas.
It will be cooler on Fri acrs the southeast plains. With the model
differences in mstr/clouds ovr the far sern plains, guidance temps
are different by around 10 deg. So, for now will split the
difference between the guidance high temp values for the far eastern
locations. One other thing to note, the NAM is also showing some
light pcpn acrs the far eastern areas thru the morning hours, but
have decided to keep the forecast dry for now due to the uncertainty.
The rest of the forecast area will be dry tonight and Friday. High
temps acrs western portions of the forecast area are expected to be
about as warm as today, with the San Luis and Upper Arkansas River
valleys see highs in the upper 50s to mid 60s.
Fri night a weak disturbance is expected to move into nrn CO late,
and may bring some snow showers to the central CO mtns, as well as
send a front into southeast CO through Sat morning. There will also
be a chance for some showers over Pikes Peak and Teller county, and
northern El Paso county Sat morning. The forecast models are
showing low level upslope flow developing in the late morning or
early afternoon hours on Sat, with the potential for showers
developing along all the eastern mtns and the adjacent lower east
slope areas. Even with the front moving thru the area, temps are
expected to be above average on Sat, with highs in the upper 50s
through the lower 60s acrs the high valleys and southeast plains.
.LONG TERM...(Saturday night through Thursday)
Issued at 357 PM MST Thu Mar 9 2017
Not many adjustments required from previous meteorological reasoning
with primary issues during the longer term continuing to be gusty
winds/elevated fire weather concerns at times, temperatures and
low grade pops at times.
Recent longer term computer simulations, PV analysis and forecast
model soundings continue to indicate that a basically dry and
warm zonal to southwesterly upper flow pattern will continue
over the majority of the forecast district during the longer term
with highest potential of generally light precipitation(over
primarily the central mountains) expected from Sunday afternoon
into Sunday night and then again by later next Wednesday with
passing upper disturbances(per PV analysis) in combination with
north-northeasterly surface surges.
Elevated fire weather concerns are still anticipated over
many southeastern Colorado locations Sunday afternoon and
evening and then again by next Wednesday. As always, WFO Pueblo
will monitor closely and issue fire weather highlights as
warranted.
The highest potential for gusty winds during the longer term
should be experienced from Saturday night into Monday night.
In addition, it still appears that temperatures will continue to
run above mid-March seasonal averages during the longer term with
warmest temperatures anticipated Sunday and then again by next
Thursday.
&&
.AVIATION...(For the 00Z TAFS through 00Z Friday evening)
Issued at 357 PM MST Thu Mar 9 2017
VFR conditions are expected at the terminal forecast sites thru the
next 24 hrs, with mainly just some high level clouds expected.
However, there is a small chance that some low clouds could move
into the vcnty of KPUB Fri morning for a short time. A front will
be moving through KCOS and KPUB tonight and will bring northerly
winds that could be gusty for awhile, but by late night the winds
are expected to become easterly and under 10kts. On Fri both KCOS
and KPUB should have southeast to east winds generally under 15 kts.
KALS should generally have light winds.
&&
.PUB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$