Wednesday, February20, 2019

Marine Weather and Tides
Lowndesville, SC

Version 3.4
What's New / NOTES
10/6/2018 Colors of tide XTide graphs changed to emphasize that they were upgraded. See next note. Comments welcome.
10/4/2018 I have fixed XTide and updated the harmonic files. There were some name changes so you might have to click EDIT to find the new station name.

Sunrise 7:09AMSunset 6:19PM Wednesday February 20, 2019 7:26 PM EST (00:26 UTC) Moonrise 7:45PMMoonset 8:04AM Illumination 98% Phase: Waning Gibbous; Moon at 16 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 Lowndesville, SC
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location: 34.23, -82.66     debug

Area Discussion for - Greenville-Spartanburg, SC
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Fxus62 kgsp 202343
area forecast discussion
national weather service greenville-spartanburg sc
643 pm est Wed feb 20 2019

Chilly high pressure atop the region will weaken through tomorrow
as a series of low pressure systems moves up from the gulf. The
moist pattern will continue well into the weekend until a cold front
finally moves through the region Sunday. After a brief break early
next week, another system will approach by mid-week.

Near term through Thursday
630 pm update... A frontal band is crossing the fa and some elevated
instability is creating deeper cells with frequent lightning across
the SRN nc br. Expect these cells to continue moving quickly
northeast and begin to weaken as updrafts are curtailed somewhat
atop the sfc wedge. Still... Elcape will be present... So we may need
to issue an additional sps or two... Yet not anticipating any sigfnt
wind or hydro issues with these cells thru the evening.

400 pm update... No sigfnt changes needed to the going fcst. Surface
temps and TD S are remaining rather steady state as the moist wedge
pattern persists. A line of general thunder pushing into the SW nc
mtns ahead of a cold front... Which is well accounted for in the

As of 2pm est Wednesday:
most of the activity through Thursday will be at the surface, as the
upper flow remains southwesterly. At the surface, a fairly
entrenched wedge of cool, moist surface air from cold-air damming,
looks to persist for awhile longer, probably becoming disrupted as
cold front reaches the southern appalachians tonight. This front
extends out of a deep surface low trough that is centered over the
great lakes region. Without much synoptic push on the front this
far south, it appears that it will stall east of, or along the
eastern edge of, the gsp cwa. With wedge persisting through today,
surface temperatures will change little until Thursday afternoon.

Ahead of and behind the front, winds become southwesterly once the
wedge is disrupted, and temperatures will actually begin to climb
with some warm advection on Thursday. Temperatures should warm on
Thursday into the upper 50s and low 60s.

Despite cool surface air, hi-res models have quite a bit of
convective updrafts along and ahead of front tonight, due to
elevated instability. Expect some thunder as line of storms near
the front passes through tonight and Thursday morning, with thunder
more likely over the mountains and foothills. Currently, rain rates
with tonight's round of convection appear to decline as the line
moves eastward into the gsp cwa. This reduces concerns about flash
flooding somewhat. Still, recent rains have some areas near
saturation. 1 hour flash flood guidance levels are 1 to 2 inches,
and with less than an inch of rain expected with the somewhat
scattered convective showers tonight, have opted not to issue a
flood watch product at this time. I wouldn't rule-out the
possibility of some localized flooding if some areas get repeated or
slow-moving showers. Deep layer shear is actually strong, upto
65kts over the mountains. This will give some chance for strong
wind gusts with the convective showers, in addition to possible

Very moist forecast soundings at low-levels due to wedge and rain
give a good chance for fog, some possibly dense, tonight into
Thursday morning. Weather forecast tonight is, therefore, somewhat
complex with rain, some thunder, and fog. Convective showers may
reduce fog transiently when they occur.

With front becoming less distinct Thursday afternoon, and a with a
lack of any upper support, chances for rain are much reduced, though
some surface-based instability does manage to develop as
temperatures warm in the afternoon.

Short term Thursday night through Sunday
As of 137 pm est Wednesday: the bulk of the late part of the week
looks gloomy and damp. Whether or not we actually break out of
our remnant pool of cool, stable air by sunset on Thursday will be
academic, because all indications are that we will be right back
in a wedge by sunrise on Friday. Overall, we stay in a moist sw
flow aloft, with the axis of the upper ridge tilting back over the
midwest such that a new sfc high will already be spilling over the
appalachians Thursday evening. Renewed isentropic lift will help to
redevelop light precip just as a new surge of cooler and drier air
comes down on the east side of the mtns to lock in a new cold air
damming wedge. Once established, this new wedge looks formidable
according to the new guidance, which shows all the trappings we
normally associate with cold air damming maintenance. Thus, the
wedge will be with us through the day Friday and Saturday, which
means relatively high precip prob with mainly light rain drizzle,
low diurnal temp change, and high temps well below normal. The
demise of the wedge is the larger question. Guidance suggests that
the wedge will scour out Saturday night in advance of a strong cold
front approaching from the west that trails out from a powerful sfc
low lifting northeastward over the upper midwest gt lakes. Nighttime
wedge destruction in february is a bad bet when the sfc low is
so far away. What's more likely to happen is a remnant cool pool
hanging on until the cold front blasts through, which guidance
suggests will be during the first half of Sunday. The downslope
flow will sweep out the old air mass around midday. Looks like a
classic case of cold front passing through, allowing temperatures
to get 15-20 degrees warmer than the day before, which always
seems counter-intuitive. This scenario would spare us much of a
threat of severe weather with the frontal passage, and hopefully
allow us to salvage Sunday afternoon with some bright sunshine.

Long term Sunday night through Wednesday
As of 225 pm est Wednesday: the forecast for the first half of
next week looks comparatively bland. The upper pattern GOES flat
on Sunday night and stays that way through Tuesday, which allows
a dry sfc high to approach Monday, move overhead Monday night,
and off the carolina coast Tuesday. Temps will be a bit above
normal. Moisture starts to return on Tuesday and Tuesday night,
but the development of precip looks like a low confidence affair
complicated by temps that could be below freezing over the nrn
mountains early Wednesday. It's often difficult to have much
confidence in a system developing in a broad flat upper ridge out
on day 7, so we will keep temps just above freezing and precip
chances only in the 30-40 pct chance range, for the time being.

Aviation 00z Thursday through Monday
At kclt and elsewhere: a cold front will cross the fcst area and
stall to the south late in the period. There are some deeper conv
cells with thunder currently across the WRN most area... However
expect these cells to weaken as they interact with a stg sfc wedge
thru the overnight. Cant rule out some thunder at any site... But the
best chances for TS will be at kavl and the upstate sc sites over
the next several hours. Thunder at kclt is too uncertain to include
in the TAF attm. CIGS and vsbys will remain low-end in a highly
moist atmos with ifr lifr conds expected thru the morning hrs. MVFR
to ifr conds into the early afternoon... With perhaps a general lift
toVFR later in the period. One caveat will be localized improving
conds as any -shra crosses... Which will help scour out vsbys and
lift CIGS toVFR levels before crashing back down to ifr or lower by
the early morning. Winds will shift from NE ly to SW ly over most
sites as the wedge breaks down... With kavl going from down to up
valley flow. Strong llvl shear associated with the frontal zone will
generate llws issues mainly across the higher terrain aft 06z.

Outlook: a series of low pressure systems will continue to move
through the region through the end of the week. This will produce
precipitation and associated restrictions for long periods of time
with each system.

Confidence table...

23-05z 05-11z 11-17z 17-18z
kclt med 69% high 83% low 56% med 78%
kgsp high 87% med 78% med 75% med 71%
kavl med 75% high 83% med 69% med 64%
khky high 87% high 83% med 75% high 85%
kgmu med 69% med 78% med 75% med 71%
kand high 81% med 78% high 81% med 71%
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:

Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
CHDS1 - Strom Thurmond Dam, SC 46 mi46 min N 4.1 G 8 43°F
LMFS1 - Lake Murray SC 74 mi66 min ENE 5.1 G 12 42°F 1020.3 hPa

Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Anderson, Anderson County Airport, SC18 mi30 minNE 54.00 miFog/Mist40°F39°F97%1021.8 hPa

Wind History from AND (wind in knots)
Last 24hrE11E14E10E12NE10NE10E13NE11NE9NE9NE12NE8NE8NE7NE9NE10NE8NE9NE7NE10NE10NE12N4NE5
1 day agoSW5W4SW7CalmNE5E4E6E10NE7NE10NE10NE9E10E10E10NE8NE9NE9NE6NE10NE9NE9
2 days agoE7E73NE4NE4CalmNW7CalmCalmSW5SW8SW4SW4W7W7W8W13W12W9W12W12W7W8W4

Tide / Current Tables for
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Weather Map and Satellite Images
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NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
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Wind Forecast for Greenville-Spartanburg, SC (19,4,5,8)
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Ground Weather Radar Station Greer, SC
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The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerious of sources and is presented automatically. It is not checked for accuracy either by anyone at or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.