Marine Weather and Tides
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 6:21AM||Sunset 7:57PM||Friday August 18, 2017 6:07 PM EDT (22:07 UTC)||Moonrise 1:50AM||Moonset 4:35PM||Illumination 12%|
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|ANZ540 Eastern Bay- 432 Pm Edt Fri Aug 18 2017 |
.small craft advisory in effect through Saturday morning...
.severe Thunderstorm watch 455 in effect until 9 pm edt this evening...
Rest of this afternoon..S winds 10 kt with gusts to 20 kt. Waves 2 ft. A chance of showers and tstms. Vsby 1 nm or less.
Tonight..W winds 10 kt. Gusts up to 20 kt. Waves 2 ft. Showers and tstms. Vsby 1 nm or less.
Sat..W winds 5 to 10 kt. Gusts up to 20 kt in the morning. Waves 1 ft.
Sat night..NW winds around 5 kt. Waves 1 ft.
Sun..NW winds around 5 kt. Waves 1 ft.
Sun night..SE winds around 5 kt. Waves 1 ft.
Mon..S winds around 5 kt. Waves 1 ft. A chance of showers and tstms through the night.
Tue..SW winds 5 to 10 kt. Waves 1 ft. A chance of showers and tstms. Winds and waves higher and visibilities lower in and near tstms.
|ANZ500 432 Pm Edt Fri Aug 18 2017 |
Synopsis for the tidal potomac and md portion of the chesapeake bay.. A cold will cross the waters tonight. A pressure trough will remain nearby for Saturday and Sunday while high pressure positions itself just to our north and west. The high will move offshore early next week. Small craft advisories may be needed Monday night and Tuesday.
7 Day Forecast for Marine Location Near Stevensville, MDHourly EDIT Help
Area Discussion for - Philadelphia/Mount Holly, PA  (on/off)  Help NOTE: mouseover dotted underlined text for definition
|Fxus61 kphi 181919|
area forecast discussion
national weather service mount holly nj
319 pm edt Fri aug 18 2017
As low pressure tracks well to our north, a cold front moves through
later tonight into early Saturday. High pressure then builds in late
Saturday and remains in place into Monday before shifting offshore.
The next cold front is scheduled to arrive during Wednesday, then
canadian high pressure builds in for Thursday and Friday.
Near term until 6 am Saturday morning
Very warm and humid airmass in place across the region with surface
dewpoints well into the 70s, and even approaching 80 in coastal
portions of southern nj. This results in an unstable environment
with sb CAPE values ranging from up to 1500 j kg across northern nj
to 2500-3000 j kg across southern nj and the delmarva. Given the
amount of instability across the region, and strong lift associated
with an approaching mid-level shortwave, active weather on tap for
Severe thunderstorm watch #455 remains in effect until 9 pm. In
addition, with pwats close to 2.5 inches across the region,
continuing to expect heavy rain and training of thunderstorms. The
flash flood watch remains in effect until midnight, but went ahead
and added all of de and all of nj to the flash flood watch, as model
guidance continues to show a precip MAX across the southern most
portions of the forecast area, mainly associated with weak low
pressure developing along the front.
Low pressure currently north of the great lakes will lift to the
north and east tonight. This will drag a cold front through the east
coast during the overnight hours. Pre-frontal trough has developed
across central ny and pa out ahead of the front, and that pre-
frontal trough will trigger showers and strong to severe
thunderstorms across much of the forecast area this evening. The
first storms that have developed are currently moving into the
lehigh valley, but that activity will spread east through the early
evening hours. Cold front swings through the region after midnight
and during the pre-dawn hours.
After sunset, with loss of diurnal heating, should lose some of the
instability that would lead to severe storms. However, flooding
threat remains in place until the storms end, as the abundant low-
level moisture remains.
The last of the storms look to move off the nj coast around
midnight. However, abundant low level moisture remains in place as
the drier airmass will not get here until Saturday morning. As a
result, can expect widespread fog to develop when rain ends and
skies start to clear out. Cannot rule out patchy dense fog.
Lows tonight remain in the upper 60s to low 70s, except for the
delmarva where lows will be in the mid 70s and the poconos, where
lows will be in the low 60s.
Short term 6 am Saturday morning through 6 pm Saturday
Cold front should be offshore early Saturday morning, and once west
to northwest winds increase a bit, the drier airmass spreads east,
and any lingering fog will burn off. Skies clear out in the
afternoon. Dewpoints drop about 10-15 degrees, generally into the
mid 60s, but temps will be fairly warm, topping off in the upper 80s
to near 90 across the urban corridor of i-95 from trenton to
wilmington, and in the delmarva. Upper trough approaches from the
west, and this may bring isolated late day showers and thunderstorms
to far western portions of the forecast area.
Long term Saturday night through Friday
Summary... Lowering of the dew points through Sunday although
remaining warm to hot, then moistures increases again with some
convection especially Wednesday with the next cold front. A
noticeably cooler and drier airmass arrives for Thursday and Friday
in the wake of the cold front.
Synoptic overview... An upper-level trough is forecast to exit the
northeast Saturday night and Sunday, then the flow aloft turns more
zonal through early next week. Another trough is forecast to amplify
across eastern canada and the great lakes to the northeast Tuesday
into Thursday, which then remains in the northeast on Friday. We
used a blend of continuity guidance for Saturday night through
Sunday night, then blended in the 12z wpc guidance.
For Saturday night and Sunday... The axis of an upper-level trough is
forecast to slide across the region Saturday night, then quickly
move across and exit new england Sunday. A short wave embedded
within this trough is forecast to move through Saturday night,
although it may shear out to the east-northeast. While some drying
is expected to move in, enough lingering moisture and instability
combined with lift may allow for some convection to arrive from the
west before weakening. We therefore carried some slight chance pops
in Saturday evening across parts of the western zones. The flow
aloft then turns more zonal on Sunday with surface high pressure
building in. This should be accompanied by more pronounced drying,
and with plenty of heating during the day Sunday the dew points are
anticipated to lower to more comfortable levels. A northwesterly
breeze on Sunday may be light enough to allow for a sea breeze to
develop in the afternoon.
For Monday and Tuesday... The zonal flow aloft continues at least
into Tuesday. This drives high pressure eventually offshore as it
weakens some later Monday. The next upper-level trough amplifies
eastward from the midwest and upper great lakes Tuesday. This will
start to back the flow more southwesterly, and there may be a lee-
side trough present on Tuesday. As the moisture begins to increase
once again combined with the possibility for some convergence and|
enough instability, some convective development is possible Tuesday
afternoon. We will carry slight chance pops as a result for Tuesday.
Any isolated convection especially inland should tend to diminish
during the night. It will turn more humid during this timeframe.
For Wednesday through Friday... The prospects for convection will
depend on the timing of an incoming cold front Wednesday. This will
be due to an upper-level trough arriving from the west, however a
pre-frontal trough may serve as the primary focus for showers and
thunderstorms. We will continue with chance pops with the idea for
at least scattered convection possible Wednesday. As of now, the
cold front should be offshore to start Thursday and canadian high
pressure builds southeastward, which arrives over our area on
Friday. A noticeably cooler and drier airmass overspreads our region
for Thursday and Friday.
Aviation 19z Friday through Wednesday
The following discussion is for kphl, kpne, kttn, kabe, krdg, kilg,
kmiv, kacy and surrounding areas.
Low-endVFR to MVFR CIGS holding tough across the terminals. There
may be some breaks toVFR from time to time, but shra tsra will
spread across the terminals ahead of a cold front approaching from
the west. Best timing for convection will be through 00z for
krdg abe, from 21-02z for the i-95 corridor terminals (kttn-kpne-
kphl-kilg), and from 22z-04z for kmiv kacy.
Heavy rain and strong and potentially damaging winds are possible
with the strongest thunderstorms. Ifr and lower conditions as well.
Once storms end, abundant low level moisture remains in place.
Ifr lifr CIGS vsbys likely in fog stratus from late tonight through
Vfr conditions develop Saturday morning. NW winds increase to 5-10
kt late Saturday morning, and back to the w-sw in the afternoon.
Isolated late day shra tsra possible at krdg kabe.
Saturday night and Sunday...VFR overall. Southwest winds 5 knots or
less becoming northwest Saturday night, then northwest winds near 10
Monday and Tuesday... MainlyVFR. Southerly winds around 10 knots.
Wednesday... Sub-vfr at times with some showers and thunderstorms
possible as a cold front arrives. Southwest winds 5-10 knots,
Sca remains in effect for the waters. Gusts to 25 kt will
develop on de bay this evening, and gusts to 25 kt along with 5
foot seas will develop on the ocean waters this evening.
Showers and thunderstorms will affect the waters as well this
evening, some of which may require special marine warnings. A severe
thunderstorm watch is in effect for de bay until 9 pm.
Tranquil conditions develop after midnight tonight, and will remain
in place through Saturday.
Fog may develop late tonight and into Saturday morning, which could
reduce vsbys down to 1 nm.
Saturday night through Wednesday... The conditions are anticipated to
be below small craft advisory criteria.
a moderate risk for the development of dangerous rip currents
remains in place for de and nj beaches through this evening.
Thunderstorms will also impact the beaches through this evening.
The rip current risk for Saturday is currently outlooked as low.
Phi watches warnings advisories
Pa... Flash flood watch until midnight edt tonight for paz060>062-
Nj... Flash flood watch until midnight edt tonight for njz001-
De... Flash flood watch until midnight edt tonight for dez001>004.
Md... Flash flood watch until midnight edt tonight for mdz008-012-
Marine... Small craft advisory until midnight edt tonight for anz450>455.
Small craft advisory until 10 pm edt this evening for anz430-
near term... Mps
short term... Mps
long term... Gorse
aviation... Gorse mps
marine... Gorse mps
Weather Reporting StationsEDIT (on/off)  Help NOTE: Click on distance to see the station location on a map
|Stations||Dist||Age||Wind||Air Temp||Water Temp||Waves||Pressure||DewPt|
|CPVM2||7 mi||50 min||85°F||82°F|
|44063 - Annapolis||9 mi||38 min||S 18 G 21||84°F||1007.2 hPa|
|TPLM2 - Thomas Point, MD||9 mi||68 min||S 20 G 22||83°F||81°F|
|APAM2 - 8575512 - Annapolis, MD||11 mi||50 min||88°F||1006.6 hPa|
|44043 - Patapsco, MD||16 mi||38 min||S 14 G 16||84°F||1007.7 hPa|
|TCBM2 - 8573364 - Tolchester Beach, MD||20 mi||50 min||SSE 4.1 G 7||85°F||82°F||1007.7 hPa|
|FSKM2 - 8574728 - Francis Scott Key Bridge, MD||24 mi||50 min||SSE 14 G 16||85°F||1006.2 hPa|
|44062 - Gooses Reef, MD||27 mi||38 min||S 16 G 18||84°F||1008.1 hPa|
|CA2 - 8571892 - Cambridge, MD||27 mi||50 min||90°F||82°F||1008.8 hPa|
|BLTM2 - 8574680 - Baltimore, MD||28 mi||50 min||N 15 G 24|
|COVM2 - 8577018 - Cove Point LNG Pier, MD||37 mi||50 min||S 15 G 18||83°F||1008.5 hPa|
|WASD2 - 8594900 - Washington, DC||39 mi||50 min||SSW 11 G 16||89°F||82°F||1006.6 hPa|
|SLIM2 - 8577330 - Solomons Island, MD||43 mi||56 min||S 12 G 15||89°F||81°F|
|44057 - Susquehanna, MD||44 mi||38 min||NNE 3.9 G 3.9||85°F||1008.3 hPa|
|DRSD1 - Delaware Reserve, DE||46 mi||158 min||S 6||91°F||1009 hPa||79°F|
|CHCM2 - 8573927 - Chesapeake City, MD||48 mi||56 min||WSW 2.9 G 5.1||87°F||83°F||1008.5 hPa|
Wind History for Tolchester Beach, MD(wind in knots) EDIT (on/off)  Help
Airport ReportsEDIT (on/off)  Help Click EDIT to display multiple airports
|Bay Bridge Field, MD||4 mi||83 min||S 13 G 17||7.00 mi||Fair with Haze||90°F||78°F||71%||1007.4 hPa|
|Annapolis, United States Naval Academy, MD||11 mi||74 min||S 17 G 25||9.00 mi||A Few Clouds||88°F||82°F||83%||1006.8 hPa|
|Easton / Newman Field, MD||14 mi||78 min||SSW 15 G 21||10.00 mi||Mostly Cloudy||91°F||78°F||67%||1009.1 hPa|
Wind History from W29 (wind in knots)
|1 day ago||Calm||N||E||Calm||SE||Calm||SE||S||Calm||Calm||Calm||Calm||Calm||Calm||S||S||S||S||S||S||S||S||S||S|
|2 days ago||NE||NE||N||Calm||Calm||Calm||Calm||Calm||Calm||Calm||Calm||Calm||N||Calm||Calm||Calm||N||Calm||NW||Calm||Calm||Calm||S||SE |
EDIT RT Ports Option Weekend mode (on/off) (on/off)  Help One Week of Data
|Kent Island Narrows |
Click for Map
Fri -- 02:27 AM EDT 2.23 feet High Tide
Fri -- 02:49 AM EDT Moonrise
Fri -- 06:21 AM EDT Sunrise
Fri -- 10:05 AM EDT 0.63 feet Low Tide
Fri -- 02:32 PM EDT 1.41 feet High Tide
Fri -- 05:34 PM EDT Moonset
Fri -- 07:55 PM EDT Sunset
Fri -- 08:51 PM EDT 0.32 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
EDIT (on/off)  Help One Week of Data
|Baltimore Harbor Approach |
Click for Map
Fri -- 02:26 AM EDT 1.12 knots Max Flood
Fri -- 02:50 AM EDT Moonrise
Fri -- 06:02 AM EDT -0.00 knots Slack
Fri -- 06:21 AM EDT Sunrise
Fri -- 09:16 AM EDT -0.93 knots Max Ebb
Fri -- 12:53 PM EDT 0.00 knots Slack
Fri -- 03:17 PM EDT 0.46 knots Max Flood
Fri -- 05:35 PM EDT Moonset
Fri -- 05:45 PM EDT -0.00 knots Slack
Fri -- 07:55 PM EDT Sunset
Fri -- 08:54 PM EDT -0.69 knots Max Ebb
Fri -- 11:41 PM EDT 0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Weather Map and Satellite Images(on/off)  Help
|Weather Map ||IR Satellite Image from GEOS|
GOES Local Image of Mid-Atlantic EDIT
Wind Forecast for Philadelphia/Mount Holly, PA (18,4,5,8)(on/off)  Help
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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 L-36.com. 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 L-36.com 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.