Forecast Discussions mentioning any of
"HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/13/20
Area Forecast Discussion
National Weather Service Flagstaff AZ
846 PM MST Wed Feb 12 2020
.SYNOPSIS...Quiet weather will continue through Sunday. Daytime
temperatures will warm to above normal values by Saturday. A
weather system brings a slight chance of precipitation to the
region Sunday night into Monday. Expect cooler temperatures early
next week.
&&
.UPDATE...
Satellite imagery from this afternoon showed a large portion of
snow cover melting in the Little Colorado River Valley. This has
led to surface dew points about 10 degrees higher than most of the
guidance has this evening. We have updated dew point forecasts
following the HRRR model overnight and added some patchy fog for
late tonight through mid day Thursday for much of the Little
Colorado River Valley.
&&
.PREV DISCUSSION /235 PM MST/...The morning cloud cover over far
eastern Arizona dissipated around 10 am, leaving us with sunny
skies and light west-northwest flow. Clear skies and calm winds
will allow for a chilly night as radiational cooling is maximized.
Additionally, remaining snow cover over eastern Arizona will aid
in cooling surface temperatures even further.
The next notable weather feature will be a dry shortwave set to
cross the region Friday night into early Saturday. The only impact
from this system is expected to be breezy west to southwest winds
on Friday and Saturday. Rising heights will result in warming
temperatures over the next few days, with daytime highs reaching
5-10 degrees above normal on Saturday and Sunday.
Long range operational and ensemble guidance continues to indicate
another trough brushing the state late Sunday into Monday. This
system has a bit more moisture to work with, so left in the slight
chances for precipitation from the previous forecast. We will
continue to monitor the track of this system over the next several
days. Temperatures look to cool behind this system early next
week, with highs currently forecast to be right around normal for
mid-February.
&&
.AVIATION...For the 06Z package...Mainly VFR conditions will prevail
through the TAF period. Patchy MVFR due to low clouds and/or fog
possible east of a KRQE-KINW-KSOW line through 14Z Thursday. Sfc
winds light. Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Dry weather and warmer temperatures will continue
for the next couple days. Light and variable winds on Thursday will
become breezy out of the southwest on Friday.
Saturday through Monday...Expect dry and warm weather for much of
the weekend. A weather disturbance will bring a slight chance of
precipitation and cooler temperatures later Sunday into Monday.
&&
.FGZ WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
PUBLIC...DL/TPS
AVIATION...Peterson
FIRE WEATHER...AT
For Northern Arizona weather information visit
weather.gov/flagstaff
Area Forecast Discussion
National Weather Service Grand Rapids MI
1017 PM EST Wed Feb 12 2020
LATEST UPDATE...
Update
.SYNOPSIS...
Issued at 330 PM EST Wed Feb 12 2020
- Accumulating snow Tonight-Thursday with Surface Low/Arctic Front
- Lake effect snow Thursday night into Friday
- Clipper system brings another shot of snow Sat-Sat Night
- System for Monday/Tuesday trends a bit cooler/more snow
&&
.UPDATE...
Issued at 1015 PM EST Wed Feb 12 2020
The arctic front is crossing Grand Travis Bay as I write this (955
pm). There is a band of heavy snow showers associated with the
front. It would seem the front is moving faster than we expected
it to. It now seems the arctic front will reach MKG by 2-3 am. It
should get to GRR by 4-5 am. That band of heavy snow showers will
just sinks south just ahead of the front. I believe our entire
CWA will see a 15 minute period of heavy snow with some blowing
and drifting snow.
What has been curious to watch is where the heaviest snowfall this
evening has been. There is frontal trough, enhanced by the core of
the upper jet being over it and an upstream shortwave over WI over
Muskegon County, Northwest Kent and Southern Newaygo County were
1 to 2 inches of snow has fallen already based on our radar snow
accumulation algorithm. It would seem to me by 7am the greatest
snowfall will actually end up being in our Lake Shore Counties
north of Holland due to the frontal trough and then the arctic
front coming through. For now I was thinking to leave our
headlines as they area as most of the snow from this system will
be during the day Thursday as the upper wave comes through behind
the arctic front.
UPDATE Issued at 642 PM EST Wed Feb 12 2020
As of 6 pm the snow has made it as far north as Three Rivers.
Based on the last few runs of the HRRR and the 18z NAMNest it
seems to me snow should reach I-94 by 7 pm and I-96 by 9 pm.
Here is the glitch through. All of the recent (since 15z) runs of
the HRRR,HRRRX,HRRRdev3, NAM and NAMNest show a break in the
snowfall over most of our CWA between 1 am and 5 am. The shortwave
associated with the arctic front redevelops the snow and that
continues over most of our CWA during the daylight hours of
Thursday. Still we get 2 to 3 inches over most of our CWA south
and east of a line from Alma to near Grandville by 4 pm Thursday.
&&
.DISCUSSION...(This evening through next Wednesday)
Issued at 330 PM EST Wed Feb 12 2020
-- Accumulating snow Tonight-Thursday with Surface Low/Arctic
Front
The snow totals have trended down a bit from this time yesterday
with the ECMWF leading the way on that trend. Totals were never
expected to be extremely heavy though with our 2-5 inch forecast
from yesterday moving towards 1-4 inches in the current forecast.
Most areas will see 1-3 inches of snow the next 24 hours (this
evening through Thursday evening), with the highest amounts
(isolated 4`s) towards BTL and JXN.
The impacts are still expected to be potentially substantial in
terms of travel given the temperature plummet late tonight and
Thursday morning. Temperatures will drop 10 degrees with in an
hour or so with the passage of the Arctic front. In the Grand
Rapids metro area for instance, the temperature is forecast to
drop from around 32F at 600am to 22F at 800am. That type of drop,
along with falling snow at the morning commute could potentially
be significant. So, dispute the lack of bigger snow totals,
impacts may be the same as an advisory with higher snow amounts.
A burst of snow will move into the forecast area from the south
this evening after dark and persist into the overnight hours. This
snow is associated with the low pressure system moving through the
Ohio Valley. Another burst will come on the Arctic front on
Thursday. This secondary burst will be on the order of a half inch
to possibly two inches. This secondary burst is the one that
coincides with the temperature plunge. Bottom line, we are
expecting impacted travel in the current advisory area and
potentially even further north across Central Lower Michigan. We
considered expanding the current advisory through Central Lower,
but held off at this point given lower totals and shorter duration
of the heavier snow. Thursday morning will be the main time frame
of concern across Central Lower.
-- Lake effect snow Thursday night into Friday
The lake effect snow still looks impactful and we will likely
transition into a Winter Weather Advisory towards the lake as we
get closer to that event. Solid lift remains in BUFKIT overviews
in a DGZ that remains off the ground. Moisture depth is limited,
but snowfall will continue towards the lake Thursday night and
Friday. Expect small flake size, snow totals in the 2-4 inch range
and potentially bigger impacts given the cold temperatures on road
mitigation efforts. Salt will not be effect given air temps in the
single digits and low teens.
-- Clipper system brings another shot of snow Sat-Sat Night
Quick hitting snow event is still in the forecast for Saturday
afternoon and Saturday night. It looks like we could see a quick
1-3 inch snow with a lake enhancement boost. The flow will be
southwest so Newaygo County may be the spot that see the most
snow.
-- System for Monday/Tuesday trends a bit cooler/more snow
The early next week system has trended a bit further south so we
may see a bit more snow on the lead edge and on the back side of
the low as well. Models still have disparity, so we have time to
lock in on a solution.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 642 PM EST Wed Feb 12 2020
I based the TAFs tonight on looking at several runs of the
HRRR,HRRRX,HRRRdev3, NAM and NAMNest and looked at radar loops and
in so doing tried my best to figure out when the snow would move
from our I-94 TAF sites (01z ) to I-96 (03z). I do not think cigs
will become IFR once the snow starts, it may take an hour or two
for the cigs to lower that much since there is still a fair amount
of low level dry air to overcome. Between 03z and 06z all TAF
sites should be IFR in snow.
As stated in the update section the HI RES models all show a break
in snow pattern between 07z and 11z (more or less). Maybe Jackson
would be least impacted by that break in the snow pattern. None
the less since all of the Hi-Res model runs have shown this since
mid morning, and it make sense given the meteorology of the
situation, I did feature a break in the snowfall in most of our
TAF sites. I did not totally stop the snow but brought the
visibility up to either VFR (MKG) or MVFR (GRR, AZO , BTL, LAN)
during that time frame.
Once the arctic front comes through expect gusty winds, snow and
blowing snow at all TAF sites. At any one location the lower
conditions with the front will last around 3 hours. I expect the
snow to start to end by late afternoon.
Lake effect snow bands will start impacting MKG by late afternoon
but will not reach the GRR or AZO taf sites will well after
midnight.
Do expect moderate to heavy icing in the clouds tonight and light
to moderate icing in the clouds Thursday. As the arctic front
pushes south of the area by midday expect only light icing in the
clouds.
&&
.MARINE...
Issued at 330 PM EST Wed Feb 12 2020
Small Craft Advisory (SCA) remains in place north of Holland for
a southwest flow event that is ongoing. Big Sable Point has been
gusting to 25 to 30 knots all afternoon and the Muskegon GLERL cam
that looks southwest has plenty of white water (waves) ongoing.
The SCA looks good.
Earlier today we upgraded to a Gale Warning for late tonight into
Thursday. There is a core of wind seen in the BUFKIT overviews at
mid lake that should be indicative of the winds over much of the
water. We should see gales from 400am through 100pm which is the
core of the wind. The incoming waves on the South Haven GLERL cam
should be solid with 6 to 9 footers expected. Points to the south
will have higher waves with 10+ foot waves expected on the south
end of the lake.
&&
.HYDROLOGY...
Issued at 330 PM EST Wed Feb 12 2020
Despite the lack of rainfall/runoff lately, river levels continue to
fall extremely slowly, due to the high groundwater levels and
saturated soils. Maple River at Maple Rapids is still near bankfull,
but should finally drop below in the next day or so.
Meanwhile, we are still expecting a fairly brief but intense blast
of cold air to move into Lower Michigan tomorrow (Thursday) and
continue through Saturday morning. This will start up the ice
machine on our rivers, and also creates the possibility of a few ice
jams forming in the area. Because it`ll be warming up quickly by
Saturday, the risk for significant jams will be lower than during
typical cold snaps, but the common trouble spots could see water
level increases as the ice piles in this weekend. These spots
include the Muskegon River between Big Rapids and Rogers Dam, the
tributaries of the Grand River like the Looking Glass and Maple
River, as well as parts of the Grand River itself near Robinson
Township. In addition, the Kalamazoo River will also be seeing new
ice formation, so the area near Comstock will have the possibility
of renewed ice jam formation as well.
&&
.GRR WATCHES/WARNINGS/ADVISORIES...
MI...Winter Weather Advisory until 7 PM EST Thursday for MIZ056>059-
064>067-071>074.
LM...Small Craft Advisory until 1 AM EST Thursday for LMZ846>849.
Gale Warning from 1 AM to 1 PM EST Thursday for LMZ844>849.
&&
$$
UPDATE...WDM
SYNOPSIS...Duke
DISCUSSION...Duke
AVIATION...WDM
HYDROLOGY...AMD
MARINE...Duke
Area Forecast Discussion
National Weather Service Wichita KS
920 PM CST Wed Feb 12 2020
.UPDATE...
Issued at 918 PM CST Wed Feb 12 2020
Last snow bands associated with the main deformation zone continues
to make slow progress to the east this evening. Now mainly located
east of the KS Turnpike. So will nix another row of counties from
the winter weather advisory for areas west of the Turnpike. Current
eastward progression of the snow suggests that the rest of the
winter weather advisory will be allowed to expire as planned at
midnight CST.
A strong cold front is currently working its way south with gusty
north winds already moving into Newton, McPherson and points north.
As the cold front moves in, temperatures are falling rapidly, with
portions of central KS already falling into the low 20s. Temperatures
are already in the low teens across southern Neb. there is some
drier air moving south, with will help evaporate or sublimate some
of the moisture on the roads, but could still see some patchy slick
spots develop from "flash freezing" by early Thu morning.
This arctic air will continue to plunge south across the area late
this evening and overnight with expected lows falling into the
single digits! Made some tweaks colder, to forecast mins, as model
certainty suggests lots of clustering of model temps closer to the
RAP and HRR min temps, which would push lows a few degrees colder.
With the expected winds overnight, even a few degrees colder will be
critical for expected wind chill values for areas near the Wichita
metro and points northeast towards EMP. Could see wind chill values
of minus 11 to minus 13.
Ketcham
&&
.SHORT TERM...(This evening through Friday night)
Issued at 305 PM CST Wed Feb 12 2020
Highlights:
1) Snow/rain will end by midnight
2) Flash freeze of residual water and slush tonight
3) Below zero wind chills on Thursday morning
4) Single digit wind chills Friday morning
Headline: Winter Weather Advisory thru midnight
A strong cold front will push southward across the region tonight
with much colder air in its wake. The snow/rain mix will continue
across the area into the evening with some light additional snow
accumulations possible. Meanwhile a second band of precipitation
looks to develop along the surface front and race southeast across
the region due to strong forcing. The main concern will be the surge
of much colder air and gusty north winds(around 40mph) spreading
southward overnight. This will cause all wet roads and surfaces to
flash freeze thus resulting in slick conditions for any untreated
roadways. Another concern will be sub-zero wind chills overspreading
the area for late tonight and daybreak on Thursday. -Jakub
After a chilly start to Thursday with surface high pressure over the
area, temperatures will rise only into the upper teens to mid 20s.
Some models suggest even lower temperatures are within the realm of
possibility which could occur with the snow cover from today. Friday
morning is going to start out cool (not as cold as Thursday morning)
with wind chills in the single digits. Despite temperatures rising
to around 40 degrees during the day, breezy winds should keep wind
chills below freezing throughout the day as mentioned in the
previous discussion.
.LONG TERM...(Saturday through Wednesday)
Issued at 305 PM CST Wed Feb 12 2020
Highlights:
1) Warm up (back to 50s) Saturday to Monday
2) Slight chances of precip (rain/snow) Monday to Tuesday
A weak wave is expected to move through on Saturday, but minimal
impacts would occur other than a wind shift. After the cool second
half to the week, there will be a stark contrast for Saturday to
Monday as high temperatures are forecast to be in the 50s with the
lower 60s anticipated along the Kansas/Oklahoma border on Monday.
Outdoor activities should flourish.
Another trough should move across at the start of next week.
Discrepancies remain in the model tracks of this system. These
differences as well as the changes in the track have resulted in
modifications to the chances for precipitation. There are only
slight chances in there at the moment. The precipitation type at
this point will be rain, rain/snow and snow. A relative cool down is
in store for Tuesday and next Wednesday with temperatures falling to
the 40s. Stay tuned for changes to the forecast.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday evening)
Issued at 550 PM CST Wed Feb 12 2020
Lingering light snow will lead to continued IFR conditions for most
of the south central and southeast KS tafs for a few more hours.
Will also carry some MVFR vsbys for the -SN or VCSH with the snow
for the KICT, KHUT and KCNU taf sites. Most of the low cigs and
most of the light snow will end early this evening, and be scoured
out, as a sharp cold front will push south across the forecast early
this evening. This will increase winds to 20 to 35 kts for most of
the late evening and overnight hours. As the cold front moves in,
the sharp front with drier air will scour out most of the low clouds
with VFR conditions returning to the area. Lots of new snow cover
across southern KS, but the wet slushy nature of the snow will keep
blowing snow chances low to near zero.
Ketcham
&&
.PRELIMINARY POINT TEMPS/POPS...
Wichita-KICT 7 23 12 38 / 50 10 0 0
Hutchinson 6 22 11 37 / 20 10 0 0
Newton 5 21 11 35 / 50 0 0 0
ElDorado 6 21 9 37 / 60 0 0 0
Winfield-KWLD 10 25 13 40 / 50 0 0 0
Russell 8 23 13 41 / 20 10 0 0
Great Bend 8 23 13 42 / 20 10 0 0
Salina 6 22 11 36 / 50 10 0 0
McPherson 5 22 10 35 / 30 10 0 0
Coffeyville 14 25 12 42 / 70 0 0 0
Chanute 10 21 9 38 / 80 0 0 0
Iola 9 20 8 38 / 80 0 0 0
Parsons-KPPF 12 23 10 40 / 80 0 0 0
&&
.ICT WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until midnight CST tonight for KSZ053-
069>072-093>096-098-099.
&&
$$
UPDATE...Ketcham
SHORT TERM...CDJ/VJP
LONG TERM...Juanita
AVIATION...Ketcham
Area Forecast Discussion
National Weather Service Northern Indiana
910 PM EST Wed Feb 12 2020
.SYNOPSIS...
Issued at 252 PM EST Wed Feb 12 2020
Accumulating snow will spread into the region from south to north
late this afternoon through the evening hours. The snow will be
heaviest early tonight...gradually tapering off Thursday morning.
Lake effect snow follows the system snow and continues into early
Friday. Much colder air follows Thursday and Friday. Temperatures
will dip into the single digits Thursday night and struggle through
the teens on Friday. The cold air will be shortlived with
temperatures back to near normal Saturday into next week.
&&
.UPDATE...
Issued at 910 PM EST Wed Feb 12 2020
Overall forecast largely on track with just some minor edits this
evening. Broad WAA/isentropic ascent in right entrance region of
potent upper jet streak supporting widespread light-moderate snow.
Some minor banding noted on radar imagery just upstream and in our
far southeast where slightly better moisture/instability reside
but overall just a widespread steady snow. Flake size has been
small at most locations and is a limiting factor for more
efficient accumulation. This forcing will be very brief as upper
jet quickly shifts east and anticipate a lull in steady snow
around 06Z but additional CVA arrives around 12Z and will support
another slight uptick in snowfall rates/coverage. There is still
some potential for freezing drizzle between the two rounds but
the window is short and most forecast soundings still indicate a
good chance of ice nucleation through the overnight. Kept
freezing drizzle mention in the forecast but limited it both
temporally and spatially (along/south of US-224). Net result in
latest update was to lower amounts slightly in our north and raise
them in our south where less melting has already supported 3-4
inches. No upgrades planned in the south as bulk of the event
will be over in the next few hours and additional amounts around
12Z are expected to be light. Steady synoptic snow still expected
to wind down shortly after 12Z but lake effect will ramp up
through the day as colder air arrives. No changes to headlines
planned this evening but extensions (or new advisories) will
likely be needed for our N/NW zones with lake effect snow
continuing into Thu night.
&&
.SHORT TERM...(This Evening into Thursday Morning)
Issued at 252 PM EST Wed Feb 12 2020
A broad trough across the Rockies forces a low pressure system to
form in conjunction with moisture along the western Gulf of Mexico.
This traverses northeast along a track through the Ohio River valley
southeast of our forecast area. High pressure across the area today
continues to push east during the day today. Very cold air still
located in southwest Canada is associated with 1035-1040 mb high
pressure, but air cold enough for snow will still be located over
the Great Lakes region with low level temps a couple degrees below
0C. This should allow for around 10:1-12:1 snow ratios.
Dynamics-wise, upper level support from a phased jet begin moving
into the area right around the onset time of snow and continue a few
hours after midnight. Also good location of -EPV over f-gen forcing
is showing up especially as the deformation zone works in from west
to east not too far after midnight. There is also some indication
from the NAM that the -EPV/f-gen forcing zone would be Soundings
also indicate a near isothermal layer up to around 600 mb below 0C
allowing for the possibility of larger aggregates moving in during a
time frame on either side of midnight. All of these would work to
create a time period of moderate to heavy snow across the area this
evening up until an hour or 2 after midnight.
Saturation to start snowing is a question with this setup. RAP time
sections for FWA and SBN indicate saturation between to 3 and 5pm.
There is some indication that snow could start out at a moderate
intensity with HREF prob of >1"/hr showing 10-30% percentages from
5pm to 10pm as the snow gets started. RAP time sections indicate a
favorable cross hair situation with a relatively moist DGZ and
highest omega in the DGZ. After about 8pm, some indication that
freezing drizzle could work in south of US-24 exists with a dry DGZ
showing up in soundings and cross sections and continuing until
around midnight as a midlevel dry slot works in. This could cut snow
totals down farther than what we already have in there in that area.
&&
.LONG TERM...(Rest of Thursday through Next Wednesday)
Issued at 252 PM EST Wed Feb 12 2020
Upper jet passes by the area by 12z Thursday and cold air advection
takes over allowing for a time frame of lake effect snow. Northwest
trajectories start after 12z Thursday when a cold front moves
southeast away from the lake. Inversion heights rise up to around
850 mb, but with good low level convergence and limited shear to
break up dendrites. Some potential exists for lake effect extending
away from the lake down towards US-24 during the day Thursday with
some instability to work with behind the cold front, but weakly
gusty winds could limit the distance away from the lake it travels.
All told, continue to expect a 1 to 2, localized 3 inch snowfall
total with the greatest totals closer to the lake mainly northwest
of a Starke county to Cass county, MI line.
High pressure noses its way into the region swiveling trajectories
around to the west and shutting off lake effect for much of the
region Friday morning. A cold airmass that is one of the top 5
coldest for this season arrives Friday morning with the entrance of
the high pressure system. Lows Friday morning drop to single digits
away from lake effect clouds to low teens underneath the lake effect
clouds. Highs Friday will only be in the mid teens to near 20
degrees within some sunshine especially in areas southwest of a
LaPorte to Portland line. However, it`s a quick rebound to
seasonable temperatures for the weekend. These temperatures are what
a clipper system has to work with as it brings a chance for snow
Saturday night/early Sunday. With those temperatures being so
marginal, I can`t rule out that snow mixing with rain for a portion
of this event. Another chance for precipitation comes in early next
week that would primarily be a rain event.
&&
.AVIATION...(For the 00Z TAFS through 00Z Thursday Evening)
Issued at 647 PM EST Wed Feb 12 2020
Moderate snow will continue through the late evening as strong
WAA/isentropic ascent wing moves through the area. 300-400ft
ceilings and 1/2SM visibilities will be possible at times over the
next few hours but held slightly higher for prevailing conditions
with these TAFs based on upstream obs and concensus of latest
numerical guidance. Parent upper jet streak exits fast and
anticipate a break in moderate snow around 05-08Z before primary
trough axis and embedded shortwave approach. This will bring
another period of light-moderate snow around 10-12Z (mainly at
KFWA). Some brief freezing drizzle is also possible at KFWA in
the 07-10Z period but confidence is too low for inclusion based on
latest forecast soundings. Lake effect snow showers then expected
on Thursday with variable but steadily improving conditions
through the day.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Winter Weather Advisory until 1 PM EST /noon CST/ Thursday for
INZ003>009-012>018-020-022>027-032>034.
Lakeshore Flood Warning from 6 AM Thursday to midnight CST
Thursday night for INZ003.
MI...Winter Weather Advisory until 1 PM EST Thursday for MIZ077>081.
Lakeshore Flood Warning from 7 AM Thursday to 1 AM EST Friday
for MIZ077.
OH...Winter Weather Advisory until 1 PM EST Thursday for OHZ001-002-
004-005-015-016-024-025.
LM...Gale Warning from 4 AM to 4 PM EST Thursday for LMZ043-046.
&&
$$
UPDATE...AGD
SYNOPSIS...Roller
SHORT TERM...Roller
LONG TERM...Roller
AVIATION...AGD
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Area Forecast Discussion
National Weather Service New Orleans LA
557 PM CST Wed Feb 12 2020
.AVIATION...
Widespread MVFR and IFR conditions will persist until late
tonight into early tomorrow for terminals west to east. Generally
a few showers here and there are expected out ahead and along the
approaching cold front. Ceilings are still generally low, winds
have gusted up into the 20 knots range, and fog may set in again
at the terminals before the cold frontal passage can flush it out.
Once it has passed, conditions should steadily improve.
-BL
&&
.PREV DISCUSSION... /issued 324 PM CST Wed Feb 12 2020/
DISCUSSION...
Much to discuss in the next 24 hours, so lets dive right into it.
Latest satellite/radar observations continue to illustrate a few
pre-frontal, shallow showers developing across the area, generally
along the northshore and west of I-59. CAM`s depicted this
possibility nicely over the previous 24-36 hours. However, so far
these still lack the vertical depth necessary for sustainable
updrafts. HRRR soundings paint a clear picture to what is going
on. As discussed in the morning update, there is a lot of dry air
in the H7-H5 layer, and surface temperatures have not warmed up
just enough yet to allow for ricing parcels to surpass this
layer. KLIX radar trends actually are scanning the tops of these
cells right around 12-14kft AGL, right at the base of this
inversion in model soundings. This will change though, as
intervals of sunshine will continue to destabilize the pre-frontal
environment. Temperatures will continue to rise which will allow
for ricing parcels (both SB and in the mixed layer) to surpass the
inversion, and grow beyond to the EL and become stronger. The
current broken line along I-55 also appears to be along a
mesoscale boundary between convergent wind flow (BTR 190
degrees/HDC 170 degrees) and will continue to drift slowly to the
northeast through the afternoon. Once larger scale destabilization
continues, more isolated cells may develop later this afternoon
and evening. Pre-storm environment continues to indicate
supportive shear conditions, which means any stronger storm may
try to rotate with an isolated tornado and damaging winds the main
threats with these. Once this first round exits later around
4-5PM, next focus will be along the actual front. Look for a
broken line of weak cells to press into our far western CWA
roughly around 6PM. As the surface low to our northwest continues
to eject northeast away from our area, so will the better
atmospheric dynamics and shear. Models are confident on surface
winds shifting more from the SSW to SW, limiting directional shear
in the vertical out ahead of the approaching broken line of
showers/storms. This will largely limit the overall severe risk,
regardless of impressive speed shear (Bulk shear around 55-65
knots).However, a few strong wind gusts cannot be ruled out,
especially along any smaller bowing segments. As the line
continues east after sunset, any lingering stronger storms will
likely diminish due to lack of supportive instability with a line
of showers working its way west of I-55 to the MS coastline by
early Thursday. Still looking like a cloudy day on Thursday with
lingering post-frontal stratocumulus. NAM shows a weak, stretched
area of vorticity riding along the progressive SW to NE flow aloft
which will try to deliver some light drizzle/showers during the
day, with better chances east of I-55 making Thursday a yucky,
gray cool and wet day. However, Friday will promise sunshine with
continued on the cool side.
Still looking like we slowly warm up through the weekend, with
the next, weak low-amplitude trough swinging across the area on
Sunday. Might be just enough moisture to allow for some scattered
showers, but will not amount to much in the way of heavy rain.
Next system beyond this one still looks to be around the middle of
next week, and remains not overly impressive in the form of
delivering any heavy rain or severe weather, but beyond that is
looking quite chilly again. Welcome to late winter along the Gulf
coast. KLG
MARINE...
Latest observations indicate improving conditions across many
marine zones, and have canceled all remaining Marine Dense Fog
Advisories in effect. However, visible satellite imagery does show
some patchy marine fog right offshore the southern MS coastline,
but does not appear overly dense and is rather localized.
HRRR/CONSShort guidance supports re-development of marine fog
later this evening, and have went ahead with marine Dense Fog
highlights beginning at 6PM CST in these areas until a cold front
sweeps it out early Thursday morning. A few strong wind gusts may
be possible along this front as it crosses from west to east
through all marine zones tonight and early tomorrow, but severe
weather appears unlikely. Also, gusty winds in Lake Pontchartrain
and Maurepas prompted exercise caution headlines from noon to 6PM
today. Winds should steadily lower after sunset. After the front
passes Thursday, northwesterly winds will persist. Still looking
like borderline Small Craft Advisory conditions beginning early
Friday through Friday night. Regardless of any headlines, gusty
northeasterly winds can be expected, along with increased
waves/seas. Conditions steadily calm going into the weekend with
no additional hazardous weather expected. KLG
AVIATION...
UPDATED 1821Z...
Advection fog and low ceilings have been slow to dissipate along
the coastal areas. KGPT still has visibility around 1sm and may
not improve much until the cold front moves through tomorrow
morning. Wind have risen to around 10 knots and increased
boundary layer mixing lifts ceilings to around 1500 to 2000 feet
for the afternoon hours. However, ceilings should lower back to
around 500 feet in the evening hours tomorrow as southerly winds
persist. Scattered showers have been spreading across the region
with thunder possible within an hour or so. A band of convection
will also begin to impact most terminals between 00z and 06z. This
convection will be associated with a frontal passage. At KMSY, a
wind shift to the west is expected by 10z as the convective band
and associated cold front pushes to the east. Gradual improving
conditions after fropa tonight.
DECISION SUPPORT...
DSS code: Blue.
Deployed: None.
Activation: None.
Activities: Marine Dense Fog Advisory - MS Sound
Day 1 Marginal Risk for Severe Weather
/Excessive Rainfall
Decision Support Services (DSS) Code Legend
Green = No weather impacts that require action.
Blue = Long-fused watch, warning, or advisory in effect or high
visibility event; Marginal risk severe or excessive rain.
Yellow = Heightened impacts with short-fused watch, warning or
advisory issuances; radar support for slight risk severe or
excessive rain.
Orange = High Impacts; Enhanced risk severe; nearby tropical events;
HazMat or other large episodes.
Red = Full engagement for Moderate to high risk of severe and/or
excessive rainfall, or direct tropical threats; Events of
National Significance.
&&
.PRELIMINARY POINT TEMPS/POPS...
MCB 52 58 37 56 / 80 20 0 0
BTR 52 57 38 56 / 70 20 0 0
ASD 54 61 39 59 / 100 40 10 0
MSY 56 60 44 58 / 100 30 10 0
GPT 56 62 41 57 / 100 40 10 0
PQL 57 65 38 59 / 90 60 20 0
&&
.LIX WATCHES/WARNINGS/ADVISORIES...
LA...None.
GM...Dense Fog Advisory until 6 AM CST Thursday for GMZ532-534-536-
538-557.
MS...None.
GM...Dense Fog Advisory until 6 AM CST Thursday for GMZ534-536-538-
557.
&&
$$
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1012 PM EST Wed Feb 12 2020
.SYNOPSIS...
The cold front will lift back north as a warm front tonight,
followed by a cold front that will cross the area Thursday Night
into early Friday. Cooler high pressure will move in late week
into the weekend.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
As of 1005 PM Wed...Warm front is now just north of Cape
Hatteras with temperatures reaching into the upper 60s and
increasing southeasterly winds. This is the only land area in
our CWA that is in the warm sector, with all other areas still
stuck in the 50s. HRRR has trended towards a slower frontal
passage and nudged the overall forecast in this direction,
favoring lighter winds and lower Td/Ts. The overall forecast
picture has not changed with the front expected to lift north
ushering a warmer airmass over the region overnight.
Prev disc...The latest analysis is showing the cold front that
pushed through early this morning is to the south of the area as
weak high pressure ridges down from the north, while a low
pressure system is developing over the lower Mississippi Valley
this afternoon. The sfc high will gradually slide off the Mid-
Atlantic coast as the low lifts northeast overnight into the
Mid-Atlantic region and prompting the cold front to the south,
to lift as a warm front this evening, which can enhance shower
activity along our coastal counties. Most of the Hi-Res models
are showing most of the light showers to be east of Highway 17.
Temps will climb through the night due to strong WAA, with lows
likely occurring shortly after sunset.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
As of 305 PM Wed... The aforementioned low pressure system will
be located over the Mid- Atlantic region with it`s associated
strong cold front approaching the area from the west. Models are
showing light showers to continue along the immediate coast
during the morning with possible isolated showers to approach
from the west and effecting the coastal plains during the
morning. The bulk of the rain will be early afternoon as models
continue to show an enhanced band of showers crossing the CWA
with the heaviest rain, closer to the coast by tomorrow evening.
Models continue to show a decent low-level jet and weak CAPE
values; while SPC has most of the area in a Marginal Threat of
severe weather tomorrow as a few strong to isolated severe
storms may occur, but think the overall severe possibility will
be fairly limited. Near record-high temperatures will be
possible, especially inland due to the warm advection ahead of
the front. Expect highs in the upper 70s to around 80 degrees
inland and low/mid 70s along the coast.
&&
.LONG TERM /THURSDAY NIGHT THROUGH WEDNESDAY/...
As of 335 PM Wednesday...A strong cold front will cross the
region Thursday evening and Thursday night, followed by a brief
cold snap. A quick return to milder weather is expected by
Sunday into early next week.
Thursday Night through Saturday Night...A cold front will push
through Eastern NC late Thursday evening through Thursday night.
There continues to be a small chance for thunderstorms during
the evening hours ahead of or associated with a line of
convection expected to cross eastern NC during the evening/early
overnight hours. If any storms were to become severe, damaging
wind gusts would be the main threat.
High pressure centered over the Midwest will build in from the
north on Friday and Saturday, then shift offshore of the Mid-
Atlantic region Saturday night. Max temps fall into the 50s
Friday and upper 40s inland to near 50 along the coast for
Saturday. Friday night temperatures will be the coldest of the
long term with lows in the upper 20s inland to mid 30s along the
coast.
Sunday through Monday...Precip forecast for Sunday is a bit
tricky, though guidance continues to suggest a weak inverted
trough forming along the NC/SC coast, while a modest shortwave
crosses the region from the west, helping support shower
production on a larger scale by late Sunday afternoon. Continued
slight chance PoPs for the afternoon with low confidence. Temps
begin to moderate into the 50s Sunday. High pressure builds in
from the north/east Monday allowing for return flow to build
temps/dew points Monday, with forecast max temps in the mid 60s
south to lower 60s north, roughly 10 degrees above climatology
for mid February.
Tuesday into Wednesday...An upper trough will dig from the
central MS valley area northeast into southeastern Canada. A
strong surface low will develop over the Ohio River Valley on
Tuesday, with strong high pressure offshore of the East Coast.
The surface low will track northeast into New England Tuesday
night into Wednesday, dragging a cold front into the region
Tuesday night and offshore of NC by Wednesday. Continued chance
PoPs for Tuesday into Wednesday, with temps well above climo,
lower 70s both days.
&&
.AVIATION /03Z THURSDAY THROUGH MONDAY/...
Short Term /through 06Z Thursday/...
As of 730 PM Wed...Predominantly MVFR conditions this evening
across the sites, but expect conditions to deteriorate as warm
front currently located along the NC/SC state line is forecast
to lift north in the next few hours. Expect more predominant IFR
conditions to begin late this evening with increasing low-level
moisture. Some patchy fog is possible immediately with the
frontal passage as winds remain light, but should quickly lift
to low stratus as southerly winds increase after 06z.
Ceilings should rise back to MVFR just before sunrise with
increased mixing and remain so for much of the day Thursday,
with the exception of locally lower visibilities/cigs with
showers and thunderstorms associated with a passing cold front
during the afternoon. Additionally, strong southwesterly winds
are expected ahead of the front with a few gusts up to 30 knots
not out of the question in the coastal plain.
Long Term /Thursday Night Through Monday/...
As of 335 PM Wednesday...A strong cold front will produce
widespread showers and isolated tstms into Thursday night with
periods of sub-VFR conditions likely. A return to VFR conditions
is expected for Fri/Sat as TAF sites remain under the influence
of dry high pressure. A few afternoon showers, associated with
a strong mid-level shortwave, may briefly reduce ceilings and
vsbys Sunday afternoon. High pressure offshore will build back
into the region on Monday.
&&
.MARINE...
Short Term /through Tonight/...
As of 735 PM Wed...Per hi-res ECMWF guidance and latest HRRR
runs, added the Ablemarle Sound and Alligator River under SCAs
early this morning to the afternoon. Otherwise current marine
forecast remains on track - sea fog is slowly making its way
along the SC coast and should make it to our southern coast in a
few hours.
Prev disc... The latest buoy observations are showing ENE winds
10-20 knots and seas 3-5 ft. A warm front will lift north
across the waters this evening, with winds becoming SE/S 15-25
knots and seas building above 6 ft late tonight. SCA will go
into effect late tonight for all the coastal waters, except the
central waters where Gale Warning. SCA will also in effect for
the Pamlico, Croatan, and Roanoke Sound, while holding off for
the Albemarle Sound and Alligator Rvr. By tomorrow, winds will
peak 15-25 knots with gusts up to 30-35 knots and seas building
to as high as 9-10 feet, especially central waters.
Sea fog is possible beginning late tonight as SW flow develops
and low level moisture values surge. However, coverage may be
limited by persistent breezy flow.
Long Term /Thursday Night through Monday/...
As of 340 PM Wednesday...A strong cold front will cross the
Eastern NC waters late Thursday night into Friday morning. Behind
the front, N winds are expected at 15-20 knots with gusts to 25
knots. Winds diminish a bit Friday, but another good surge
expected Friday night with gusts up to 30 knots again possible.
Rough seas continue through midday Saturday, before subsiding.
As high pressure moves offshore, SW winds develop Sunday at
mostly 10-20 knots, with seas of 2-4 feet.
&&
.CLIMATE...
Record High temps for 02/13 (Thursday)
LOCATION TEMP/YEAR
New Bern 83/2017 (KEWN/ASOS)
Cape Hatteras 70/2019 (KHSE/ASOS)
Greenville 83/1932 (Coop - Not KPGV AWOS)
Morehead City 74/1984 (Coop - Not KMRH ASOS)
Kinston 81/1965 (Coop - Not KISO AWOS)
&&
.MHX WATCHES/WARNINGS/ADVISORIES...
NC...None.
MARINE...Small Craft Advisory from 4 AM to 7 PM EST Thursday for AMZ135.
Small Craft Advisory from 4 AM to 3 PM EST Thursday for AMZ131-
230-231.
Gale Warning from 5 AM to 7 PM EST Thursday for AMZ152-154.
Small Craft Advisory until 7 AM EST Friday for AMZ156-158.
Small Craft Advisory from 4 AM Thursday to 1 AM EST Friday for
AMZ150.
&&
$$
SYNOPSIS...MHX
NEAR TERM...BM/MS
SHORT TERM...BM
LONG TERM...CTC
AVIATION...CTC/MS/ML
MARINE...CTC/BM/MS
CLIMATE...MHX
AREA FORECAST DISCUSSION...UPDATED
National Weather Service Morristown TN
715 PM EST Wed Feb 12 2020
.UPDATE...
EVENING UPDATE.
&&
.DISCUSSION...
A quick update will be issued to account for the faster speed of
the convective line that has been moving across N AL and Middle
TN. Wind damage reports have been numerous with this line, with
some rotation signatures embedded in it. While it is expected to
weaken as it moves east, the southern portions of our area closest
to a boundary across N GA will have the greatest threat of severe
storms/tornadoes over the next few hours.
DGS
&&
.AVIATION...
00Z TAF DISCUSSION.
A narrow convective line will be passing through the area in the
next few hours, bringing IFR conditions with the heaviest rainfall
and a chance of TS at CHA. Gusty winds of 30-40 kts can also be
expected. Ahead of the line, LLWS will be present at all sites.
Behind the line, LLWS should end and lighter rain should allow vis
to rise to MVFR, but with cigs remaining IFR. A wind shift to
westerly will occur toward morning with a frontal passage, with
cigs lifting to MVFR - potentially VFR at CHA - during the day.
DGS
&&
.PREV DISCUSSION...
/ISSUED 339 PM EST Wed Feb 12 2020/
SHORT TERM (Tonight and Thursday)...
Current satellite imagery and surface observations show a warm
front across north GA and AL with dewpoints in the 60s within the
warm sector. North of the front across our area, dew points remain
in the 40s with a more stable airmass and an inversion near the
850mb level. Downslope flow is evident on visible satellite
imagery across portions of Blount, Sevier, Cocke, Greene, Unicoi,
and Carter Counties with breaks in low-level cloud cover.
As the low-level jet strengthens in response to the 180kt upper
jet streak across the Great Lakes and Ohio Valley, warm and moist
boundary layer air will be transported northward overnight. For
this reason, temperatures will rise overnight ahead of the frontal
boundary and line of convection. As dew points approach the upper
50s and lower 60s across northern AL/GA and southern TN, RAP
guidance shows MLCAPE near 200 J/Kg across the southern counties
of Marion, Sequatchie, Hamilton, and Bradley. The weak
instability will greatly limit the severe potential, but with at
least marginal surface based instability possible and low-level
shear being very strong, there will be at least a chance of
damaging wind gusts and a low chance of a brief QLCS tornado with
the line of thunderstorms across the southern Cumberland Plateau
and southern Tennessee Valley near the AL/GA borders in this high
shear / low CAPE environment.
The strong LLJ will result in very strong winds across the
mountains and foothills tonight. With S/SSW winds of 70kt and the
pressure gradient across the mountains, this will be a favorable
setup for mountain wave high winds. Will increase max winds in the
High Wind Warning to around 80mph because of the anomalously
strong LLJ magnitude.
Will continue the Flash Flood Watch, but believe the overall
flash flood threat to be low and isolated. With PW values of up to
1.4 inches, this will favor heavy rainfall. However, the quick
forward motion of thunderstorms tonight will limit overall
rainfall amounts and limit flooding issues to regions of locally
heavy downpours. Expect the Flash Flood Watch can be cancelled by
12z as the line of rain and embedded thunderstorms should have
exited the area.
In the wake of the cold front, winds shift to the WNW/NW on
Thursday with drier and cooler air advecting into the region.
Cloud cover will slowly decrease with some clearing by the
afternoon across downslope regions of the valley downstream of
the plateau. With colder air across the higher elevations, could
end the day with a few flurries or light snow showers across the
highest elevations of the mountains, generally at or above 4000
feet. Amounts would be light and limited to a few tenths of an
inch or less.
JB
LONG TERM (Thursday night through Wednesday)...
A reinforcing shot of cold air will surge into the area Thursday
night and early Friday. There may be a few sprinkles or flurries
around mainly northeast Thursday night, then Friday will be cold
with high temperatures well below seasonal normals despite
increasing sunshine. A short wave ridge aloft and surface high
pressure will keep things dry for the first part of the weekend
with moderating temperatures.
By Sunday and beyond forecast uncertainty is higher. The models
indicate there may be some weak short wave energy moving across the
area at times during the Sunday through Monday period, but differ on
strength/timing/placement. Will have more clouds and carry low PoPs
for Sunday, Sunday night, and Monday, but it is doubtful that we
will see precipitation in our area all three periods and if
precipitation does occur it will likely be light. By Tuesday the
next frontal system will be moving in, with better chances for
precipitation for the end of the long term period. Temperatures look
warm enough for this to be a mainly rain event.
LW
&&
.MRX WATCHES/WARNINGS/ADVISORIES...
NC...Flash Flood Watch until 7 AM EST Thursday for Cherokee-Clay.
TN...Flash Flood Watch until 7 AM EST /6 AM CST/ Thursday for
Anderson-Bledsoe-Blount Smoky Mountains-Bradley-Campbell-
Claiborne-East Polk-Grainger-Hamilton-Hancock-Knox-Loudon-
Marion-McMinn-Meigs-Morgan-North Sevier-Northwest Blount-
Northwest Monroe-Rhea-Roane-Scott-Sequatchie-Sevier Smoky
Mountains-Southeast Monroe-Union-West Polk.
High Wind Warning until 7 AM EST Thursday for Blount Smoky
Mountains-Cocke Smoky Mountains-Johnson-Sevier Smoky
Mountains-Southeast Carter-Southeast Greene-Southeast
Monroe-Unicoi.
VA...Flash Flood Watch until 7 AM EST Thursday for Lee.
&&
$$
Area Forecast Discussion
National Weather Service Tampa Bay Ruskin FL
706 PM EST Wed Feb 12 2020
.UPDATE...
Latest RAP model has mid/upper level ridging...centered near the
Bahamas...beginning to slide eastward later tonight and Thu as a
long wave trough...currently from the Upper Midwest to the
southern high plains...pivots into the Deep South during Thu.
Atlantic high pressure across FL to the Gulf of Mexico pulls away
to the east as a cold front...accompanying the long wave trough...
moves into north FL and southwestward across the Gulf late Thu.
Deep southerly flow will provide adequate moisture for patchy to
areas of fog to form under some cloudiness later tonight and
continue into mid Thu morning. The approaching front and long wave
trough will provide additional moisture and support for showers
in the slight chance to chance range. These will impact Levy
County in the afternoon then spread south to around Tampa Bay
late afternoon or early evening.
&&
.AVIATION...
13/00Z TAFs. Prevailing VFR gives way to MVFR BTWN 06Z and 19Z
with TEMPO IFR 10-14Z...mainly for CIGS although there will be
some patchy BR. Light S winds become SW at 11-15KT AFT 18Z.
&&
.MARINE...
Patchy to possibly dense sea fog will continue to impact the
waters for the next 24 hours or so. Then a front pushing in will
bring showers followed by slightly drier air on northwest flow.
This will help scour out the fog but increase winds and seas into
the caution to advisory range during Fri. Relaxed high pressure
behind the front builds in for the weekend with winds veering and
diminishing.
&&
.Preliminary Point Temps/PoPs...
TPA 67 81 65 74 / 0 30 30 20
FMY 68 83 67 79 / 0 10 0 10
GIF 67 86 66 76 / 0 0 10 30
SRQ 67 82 66 76 / 0 0 20 20
BKV 64 84 61 74 / 0 30 30 20
SPG 67 81 65 74 / 0 30 30 30
&&
.TBW WATCHES/WARNINGS/ADVISORIES...
FL...None.
Gulf waters...None.
&&
$$
UPDATE/AVIATION/MARINE...09/Rude
UPPER AIR...04/Sobien
DECISION SUPPORT...42/Norman