Tuesday, January16, 2018 L-36.com


Marine Weather and Tides
Grenada, MS

Version 3.4
What's New / NOTES
6/25/2017 - NOAA is having a major issue that impact the 7 day forecast load times. Many users are reporting problems. The issue has been reported.
5/23/2017 - Worked with NOAA again to speed up the 7 day forecast load times. Thanks to them for being responsive.
5/19/2016 - There were issues with the 3 day airport observation history. I switched to another data source. Let me know if you see any issues with the data feeds.

Sunrise 7:02AMSunset 5:18PM Tuesday January 16, 2018 1:01 PM CST (19:01 UTC) Moonrise 7:38AMMoonset 6:07PM Illumination 0% Phase: New Moon; Moon at 29 days in cycle
NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.
Marine Forecasts
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7 Day Forecast for Marine Location Near Grenada, MS
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location: 33.78, -89.81     debug


Area Discussion for - Jackson, MS
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Fxus64 kjan 161816
afdjan
area forecast discussion
national weather service jackson ms
1216 pm cst Tue jan 16 2018

Accumulating snow continues through late evening, dangerous cold
through midweek...

Update
Updated for morning update and 18z aviation.

Discussion
Light snow (with some sleet mixed in across the far south) continues
to move across the area today ahead of a potent mid upper trough
swinging into the mid-south. Temperatures continue to drop like a
rock in the wake of a strong arctic front. Essentially all areas N w
of a mccomb to meridian line are now below freezing and will remain
that way through the remainder of the day and beyond. The small area
that remains above freezing will be falling below freezing within
the next few hours. As we cross midday, temps are in the teens at
cleveland and winona. Snow is tapering off across upper portions of
the delta, with even a few breaks in the clouds already sneaking in
to ashley and chicot counties. A tier of counties farther south east
was added to the winter storm warning as we began to receive a few
2" reports around bastrop start oak grove on the perimeter of the
previous warning area. Otherwise, with snowfall rates remaining
rather low, the accumulation forecast is largely panning out as
anticipated so far. The bigger concern, regardless of exact amounts,
is travel impact. In areas where snow has been accumulating, roads
have become hazardous and there are numerous traffic accidents. With
temperatures in the teens and 20s, those issues will not go away
anytime soon.

Looking ahead through the remainder of the event, wintry precip will
begin to move into the i-59 corridor and the pine belt within the
next few hours. Reports over far S mississippi SE louisiana and
latest SREF guidance suggests there could be more sleet than snow or
a sleet snow mixture in that area at the beginning of the precip,
gradually transitioning to all snow to the south. The 12z nam
depicted a subtle shortwave moving across the southern portion of
the area later this afternoon, which may provide some enhancement in
the precip shield. This area is already covered by a winter weather
advisory, but we did expand the "elevated" area a tad farther
southward and bump up accumulations ever so slightly as this does
increase concern for travel issues a bit farther south. This wave
might also cause light snow to hang around just a touch later into
the evening, but not enough to cause a major change in previous
timing impact expectations.

We have been making regular minor adjustments to the forecast
through the morning to keep track with the latest observational
trends and will continue to do so into the afternoon. We appreciate
any and all reports of winter accumulations and road conditions
today! Dl
prior discussion below:
today:
arctic front is racing through the region, bringing increasingly
cold air and wintry precipitation quickly filtering into the delta
area. Expect this pattern to only continue as cold air advection
(caa) quickly overtakes the moisture ascent in the wake of the cold
front. The synoptic pattern consists of a deep longwave trough
digging through the central portions of the nation, mainly along and
east of the rockies. This is helping to drive this arctic cold front
& anomalously strong 1045-1050mb surface high currently over the
northern to central plains. This strong ridging extends well south
into ARKLATEX and arklamiss, keeping cold air advection locked in.

On the northern side of the cold front, moisture ascent & favorable
jet dynamics in the right entrance region, in addition to nearly a
half inch to three quarters of an inch pws, is helping light snow be
developing across the delta region. The back side of the subsidence
in the wake of the cold front is moving into south-central arkansas.

Overall, we are continuing to expect as the trough digs to the south
and isentropic moisture ascent continues, moisture will quickly
begin to fill in from northwest to southeast through the day. For
the most part, temperatures will be falling into the afternoon in
the 20s while really only in interstate 59 corridor where
temperatures could reach above freezing. Due to this, most of the
area should begin to develop as light snow & stay that way
throughout the event. Local ulm sounding to our west shows that any
limiting issues in the mid-levels (snow growth region ~ -12 to -18
deg c) is not as much of a problem as the forecast soundings were
indicating, which would have held down totals. Kept the official
forecast mostly all snow as it first shortwave progresses across,
while areas in the southeast could have a trend towards light
rain sleet prior to changing over to snow, mainly in the pine belt.

However, wet-bulbing and evaporational cooling, due to caa, should
help cool the column for all snow across the area by later today.

Expect as the first shortwave moves southeast, the snow band should
slowly weaken somewhat but still should make it into central
portions of the area, especially the i-20 corridor. In addition,
models continue to indicate there could be a secondary shortwave
that could help increased isentropic moisture ascent and another
light band of snow that could move back over along and southeast of
a line from natchez to meridian, ms. Right now this can't be ruled
out but for now don't think it would have a significant enough
affect to modify the current thinking. But these trends will have to
be monitored, especially with higher travel impacts due to dry snow
in a sub-freezing environment. Overall this will be a dry snow and
expect ratios to be in the 10-12:1 ratio in central portions of the
area while closer to 15-17:1 ratios in the delta. This should help
higher accumulations even with limited QPF forecasts (0.05-0.2
inches or so across the region).

Generally, the totals for the system have remained nearly the same,
maybe with a slight uptick in QPF and snow totals across the delta.

These areas could see 2-3+ inches, maybe locally higher, while along
and northwest of a line from noxubee to lawrence county could see up
to a half inch to 2 inches closer to the natchez trace corridor.

Areas southeast of that line could see up to a half inch of snow.

For now, our official forecast doesn't reflect too much influence
from the secondary wave but if it has enough qpf, could potentially
add another half inch or so across the region. Due to these
adjustments, expanded the winter storm warning to include grenada &
carroll county. Also expanded the "significant" area to include more
of the delta. Rest of the area for the winter weather advisory
remains the same, other than removing the two counties that were
part of the winter storm warning that remains in effect through this
afternoon. With this being a drier snow & temperatures being in the
20s & us being in the 50s yesterday, significant travel impacts are
possible due to the melting & refreezing of the snow. Utility
impacts are much less likely than they were with our december winter
storm. Though they are possible, confidence in travel impacts in the
pine belt is lesser than areas to the northwest, unless the
secondary wave overachieves with snowfall early this afternoon.

Regardless, prepare for slick roads & difficult to dangerous travel
across the region.

The timing this remains mostly the same as it should be
in the delta & winter storm warning area through around noon,
towards the natchez trace corridor by daybreak & lasting through
around mid-afternoon (6am-3pm), southeast of natchez trace corridor
from natchez to jackson metro to golden triangle around mid-morning
& lasting through through late afternoon (8am-5pm) and southeast
mississippi in the highway 84 & i-59 corridors by early afternoon
through late evening (1pm-9pm). Expect the snow to slowly taper off
as we go into the evening as the snow moves off into southeast
mississippi.

In addition to the snow, wind chills will be widespread in the low
teens to 20s over most of the area (except in the pine belt) while
gusty winds in the wake (upwards of 25-30mph in the delta) could
bring wind chills only reaching the single digits this afternoon.

Due to that, added a "limited" in the hwo for wind chills today and
added a wind chill advisory for this area in the delta. However,
even more dangerous cold & wind chills are expected tonight across
the entire area, where a wind chill advisory already was in effect.

Dc
tonight through the first part of next week:
still will probably be some light snow ongoing early this evening
across portions of southeastern ms (the pinebelt) but all snow
should be gone by around 9 pm. Thereafter the big story tonight
will be the continually plummeting temperatures with lows expected
to be well down into the teens by daybreak Wednesday. We still
cannot rule out a few single digit actual air temperatures up
along and north of the highway 82 corridor. Up in that neck of the
woods wind chill values late tonight should dip at least briefly
below zero in many areas with all locations seeing single digit
wind chills late tonight.

Wind chills may take until late morning on Wednesday to recover
out of the single digits but gradually slackening winds through
the day will help out with the improvement. Sunshine should
prevail through the bulk of the day but the arctic air mass in
place will hold high temperatures into a range from the upper 20s
to lower 30s along and north of a line from natchez to meridian
with highs south of that line maybe sneaking a degree or two above
freezing for only an our or two in the afternoon. As the Sun sets
Wednesday evening anticipate calming winds to allow the
temperatures to again plummet thanks to good radiational cooling.

Any snow cover that managed to stick around through the sunshine
Wednesday will only exacerbate quickness of cooling and ultimate
minimum temperatures. For now we expect another night of low
temperatures well down into the teens. If it turns out some
significant patches of snow cover remain into Wednesday night
there may be some single digit lows near that snow.

The brunt of the arctic air mass will really be moving out
Thursday with some westerly flow above the surface offering
potential for good mixing and warming. However, we are thinking
the cold frozen ground will work again efficient warming although
temperatures should get comfortably above freezing in the
afternoon (even in the arklamiss delta). We inherited a hard
freeze warning expiring in the late morning Thursday and our
forecast does not require an adjustment of that thinking. Despite
the warming trend we still expect a cold (just not quite as cold)
night Thursday night with lows well down into the 20s, especially
across eastern mississippi.

The warming trend will fortunately continue Friday and into the
weekend as the larger scale pattern changes and trough energy
starts digging through the four corners region and into the
plains. There is a slight chance for some rain showers entering
back into the picture in western zones with southerly flow picking
up Saturday into Saturday night. However, the bulk of big rain (and
even associated thunderstorm) chances will likely hold off until
later Sunday into Sunday night when the aforementioned progressive
trough brings a pacific-type cold front into the region. There is
non-negligible potential for some heavy rain issues in this time
frame but we will watch it for another day or two to build
confidence before worrying about inclusion in the hwo graphics.

Following the late weekend FROPA the model consensus decreases,
but in all likelihood conditions should dry out for at least a few
days with the air mass coming in the wake of the cold front not at
all of arctic origin. Bb

Aviation
18z TAF discussion:
light snow continues across the area this morning and into the
afternoon. This has dropped visibilities at times to mfr and ifr
conditions. Ceilings have also been down to ifr categories this
morning. Expect this to continue through the afternoon while snow
continues across the area. Once it moves out from west to east,
ceilings should gradually improve back toVFR and all sites should
beVFR by this evening. In addition, gusty northerly winds are
also occurring with most locations seeing sustained speeds around
10-15kts and gusts occurring in the delta around 20-25kts at
times. 28

Preliminary point temps pops
Jackson 14 32 15 44 99 13 0 0
meridian 14 33 15 45 92 25 0 0
vicksburg 15 29 14 42 100 8 0 0
hattiesburg 17 36 17 46 100 69 0 0
natchez 15 31 16 45 100 15 0 0
greenville 13 27 15 38 50 1 0 0
greenwood 11 27 13 40 88 1 0 0

Jan watches warnings advisories
Ms... Hard freeze warning until noon cst Thursday for msz018-019-
025>066-072>074.

Winter weather advisory until 6 pm cst this evening for
msz029>033-037>039-043>050-053-054-059-060.

Wind chill advisory from 6 pm this evening to 10 am cst
Wednesday for msz026>033-036>039-042>066-072>074.

Winter storm warning until 3 pm cst this afternoon for msz018-
019-025>028-034>036-040>042.

Winter weather advisory until midnight cst tonight for msz051-
052-055>058-061>066-072>074.

Wind chill advisory until 10 am cst Wednesday for msz018-019-025-
034-035-040-041.

La... Hard freeze warning until noon cst Thursday for laz007>009-015-
016-023>026.

Winter weather advisory until 6 pm cst this evening for laz016-
023>026.

Wind chill advisory from 6 pm this evening to 10 am cst
Wednesday for laz007-015-016-023>026.

Winter storm warning until 3 pm cst this afternoon for
laz007>009-015.

Wind chill advisory until 10 am cst Wednesday for laz008-009.

Ar... Hard freeze warning until noon cst Thursday for arz074-075.

Wind chill advisory from 6 pm this evening to 10 am cst
Wednesday for arz074.

Winter storm warning until 3 pm cst this afternoon for arz074-
075.

Wind chill advisory until 10 am cst Wednesday for arz075.

Dl 28


Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Greenwood, Greenwood-LeFlore Airport, MS24 mi69 minN 109.00 miOvercast20°F12°F71%1038.9 hPa

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Last 24hrS7S6SW4NW3SE3CalmN4N8N7NE7N10N9
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1 day agoN8N7NE5NE6E3SE4SE6S3CalmCalmCalmCalmCalmCalmCalmCalmCalmCalmCalmS5S8S9SW36
2 days agoN105NW7N7N6N5N7N5N3N7N3N6NE3N4N3NE7NE5NE4NE5E7NE54N3N5

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Wind Forecast for Jackson, MS (14,3,4,5)
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