Wednesday, May23, 2018

Marine Weather and Tides
Lake Norman of Catawba, NC

Version 3.4
What's New / NOTES
5/20/2018 -- NOAA is having problems with the data feed that I use to draw the graphs. They are aware of the issue and working to resolve it. Sometimes changing the location by about a mile will give a correct graph. 3/3/2018 - There is a new GOES Satellite for the east coast that required rewriting that part of the code. Please report any issues.

Sunrise 6:10AMSunset 8:29PM Wednesday May 23, 2018 11:11 AM EDT (15:11 UTC) Moonrise 1:43PMMoonset 1:59AM Illumination 63% Phase: Waxing Gibbous; Moon at 9 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 Lake Norman of Catawba, NC
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location: 35.6, -80.98     debug

Area Discussion for - Greenville-Spartanburg, SC
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Fxus62 kgsp 231040
area forecast discussion
national weather service greenville-spartanburg sc
640 am edt Wed may 23 2018

A moist air mass will remain over the area through today, with good
chances for showers and thunderstorms in the afternoon and evening.

A weak backdoor cold front will then move into the forecast area from
the north later tonight and into Thursday and allow for some brief
drying across north carolina. As a tropical low develops over the gulf
of mexico, deep tropical moisture will overspread the area over the
weekend and persist into early next week.

Near term through tonight
As of 630 am edt Wednesday: only minor changes to morning
temperature trends with the sunrise update. Did made several
adjustments to pops to lower this morning and trend into the going
forecast this afternoon; cams continue to be generally less and less
excited about convective potential this afternoon (we'll take it...

if it's right, that is!) with the drying air aloft, 500-600mb
warming, and actually some drier surface air all working to help
suppress convection, though CAPE still progged at 1200-1500j kg. In
the end, did not feel comfortable making huge adjustments to
afternoon pops, but did decrease through the morning.

Otherwise, a broad upper trough is pushing across eastern canada and
new england this morning, with a shortwave rotating toward the
appalachians at afd time. The former subtropical upper low, now just
a bit of a weakness, remains in place over ga, as upper ridging
continues to build over the center of the country. The eastern
trough is pushing the western atlantic upper high farther south
toward the bahamas, and the center of the surface high off to the
east, though westward ridging toward the south atlantic bight
remains in place. Surface front associated with the upper trough is
making its way down the mid-atlantic states, with a bit of pre-
frontal troughing remaining in place across the nc sc ga piedmonts
which will be absorbed by the incoming front today. The "front" is
really just a wind shift as no airmass change will be expected
behind it as we push toward the short term. Highs pretty close to
seasonal normals today, and lows still 8-10 degrees above.

The big change for today will be the intrusion for dry air aloft,
generally 500mb and above but some creeping as far down as 700mb.

This will help to limit the efficiency of the rainfall processes,
and of course pws will be lower today (more like 1.5" vs 1.75-1.8"
that we've been seeing). However, with the triggering mechanism of
the front, a little upper support from the weak dpva, we could see a
little more intensity to the storms. Nothing significant; deep-layer
shear is at best 20kt, but the mid-level dry air entrainment could
lead to some gusty winds especially with the steep low-level lapse
rates and improving mid-level lapse rates. And even with the lower
pws (just one ingredient of many for potential flash flooding),
soils remain very moist and it will not take much to cause
additional problems. Cams seem to be pointing to a round of
convection initiating over the mountains and pushing off the
escarpment late this morning, drifting southeast and slowly
dissipating, with another round of convection triggering in the nw
piedmont along the front late this afternoon and evening. It would
really be this second round that would carry the minimal severe
weather concern. SPC has us in general thunder for day 1 which seems
perfectly fine given the very low-end concerns. The wpc excessive
rainfall outlook does not actually outline any of our areas today,
but areas along the escarpment that may see the initial convection
later this morning will need to be watched closely given previous
days' rainfall.

Short term Thursday through Friday night
As of 255 am edt Wednesday: the short-term fcst picks up at 12z on
Thursday with steep upper ridging spreading over the eastern conus
from the west and deamplifying in the process. Although upper ridging
will remain over the region thru the rest of the period, fairly stout
shortwave activity moving into the great lakes region will act to
suppress the ridging to some degree. At the sfc, a fairly robust
canadian high will move south and over the great lakes before the
start of the period. On Thursday, the center of the high will move
se of the great lakes and try to push some of the moist sly flow
south of the fcst area. The result is that much of the deeper moisture
is pushed just south of nc, while sc remains under the deeper moisture.

By early Friday, the high begins to drift offshore as low-lvl flow
remains out of the east becoming more southeasterly later in the day.

As this happens, the deeper moisture begins to overspread western
and central nc again. By early sat, a tropical low is deepening over
the northern gulf of mexico and bringing another surge of deeper
moisture over the entire fcst area. As for the sensible fcst, no
major changes were needed. Moderate instability and a weakly sheared
environment will support pulse-type convection, with a minimal severe
threat, each afternoon evening. Also, the risk remains high for
additional flooding thru the period, especially for areas that have
wet antecedent conditions. High temps are expected to be a degree or
2 above normal, while low temps will be about 6 to 8 degrees above
normal each day.

Long term Saturday through Tuesday
As of 245 am edt Wednesday: the extended fcst picks up at 12z on
Saturday with the persistent upper ridge being flattened as a broad
upper trof axis moves off the coast of nova scotia. By late Sat early
Sunday, an upper low develops over the northern gulf of mexico and
slowly drifts northward over the gulf coast. On Monday, the latest
model guidance has the low moving inland, however with the weak steering
flow aloft the models vary quite a bit with the track. By the end
of the period late Tuesday, the upper low is still expected to be
centered somewhere over the southeast. At the sfc, a tropical low
associated with the above mentioned upper low, will deepen over
the gulf of mexico and move northward and towards the gulf coast.

Quite a bit of uncertainty remains with the track of this system
as it moves onshore. The ECMWF and canadian models remain more in
synch with each other. They have the low gradually moving onshore
over the gulf shores new orleans region and then essentially stalling
out just north of there thru day 7. The gfs, on other hand, moves
the low northward over florida on Sunday and then has the system
slowly track farther north and become less organized as it does.

At this point, the GFS solution still appears the least likely,
but it has been varying quite a bit from run to run. Regardless,
we can expect more deep moisture and nearly saturated profiles
over the fcst area from early Sat onward. High temps are expected
to remain near normal, if not slightly above, while low temps will
remain well above normal.

Aviation 12z Wednesday through Sunday
At kclt and elsewhere: MVFR to patchy ifr (and isolated lower) cigs
are in place across the area this morning, with a few holes here and
there. Guidance trend is to continue delaying improvement until noon
or possibly shortly thereafter, and did delay the improving trend in
the TAF but not quite as much as new guidance is indicating; will
have to monitor through the morning. Expect another round of
convection this afternoon though coverage looks less than earlier
anticipated; have continued vcts everywhere with a tempo tsra at
kclt, trending to prob30s later in the afternoon that will have to
be updated with later amds. Winds remain light SW today, though with
the front coming down expect a wind shift overnight with winds on
the NE side for kclt by daybreak Thursday. Guidance hinting at
another round of MVFR CIGS Thursday morning as well and have
included this for all sites.

Outlook: the unsettled pattern will continue the rest of the week,
with flight restrictions possible each day under diurnal showers and
thunderstorms. Tropical moisture may increase through the late
weekend. Morning stratus fog are possible each day - especially
following heavy rain the previous day.

Confidence table...

10-16z 16-22z 22-04z 04-06z
kclt med 75% high 94% high 100% high 100%
kgsp med 68% high 100% high 100% high 100%
kavl med 76% high 100% high 100% high 100%
khky med 72% high 100% high 100% high 100%
kgmu high 86% high 100% high 100% high 100%
kand high 83% high 86% high 100% med 79%
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
WATS1 - Lake Wateree, SC 89 mi41 min WNW 5.1 G 7 78°F

Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Statesville Municipal Airport, NC11 mi16 minSW 310.00 miPartly Cloudy76°F74°F95%1019 hPa
Lincolnton, Lincolnton-Lincoln County Regional Airport, NC13 mi16 minW 710.00 miPartly Cloudy78°F67°F70%1019.3 hPa
Concord Regional Airport, NC20 mi21 minW 610.00 miFair81°F69°F70%1019.6 hPa
Hickory, Hickory Regional Airport, NC24 mi18 minN 010.00 miFair77°F69°F77%1017 hPa

Wind History from SVH (wind in knots)
Last 24hrSW6SW5SW6SW5S5SW9S6SW5SW4SW5CalmSW3S3CalmSW4S5CalmCalmCalmCalmCalmSW4W4Calm
1 day agoCalmCalmSE3E5CalmCalmCalmCalmNE5NE3CalmCalmCalmNE3N3NE3CalmCalmCalmCalmCalmCalmSW4SW4
2 days agoS3W3SW4SW5SE4CalmS3SE3SW4SW4W7CalmCalmCalmW4W4CalmCalmS5W3CalmCalmCalmCalm

Tide / Current Tables for
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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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Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for Greenville-Spartanburg, SC (11,2,3,4)
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Ground Weather Radar Station Greer, SC
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