Monday, December18, 2017

Marine Weather and Tides
Grasonville, MD

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 7:16AMSunset 4:46PM Monday December 18, 2017 4:09 AM EST (09:09 UTC) Moonrise 7:21AMMoonset 5:24PM Illumination 0% Phase: New Moon; Moon at 0 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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ANZ540 Eastern Bay- 331 Am Est Mon Dec 18 2017
Rest of the overnight..SW winds 5 kt. Waves flat.
Today..SW winds 5 kt. Waves flat.
Tonight..SW winds 5 kt. Waves flat.
Tue..SW winds 5 to 10 kt. Waves 1 to 2 ft.
Tue night..W winds 10 kt with gusts to 20 kt. Waves 2 ft.
Wed..NW winds 5 to 10 kt. Waves 1 ft.
Wed night..N winds 5 to 10 kt. Waves 1 ft.
Thu..SE winds 5 to 10 kt. Waves 1 ft or less.
Fri..S winds 10 to 15 kt. Waves 1 to 2 ft. A chance of rain through the night.
ANZ500 331 Am Est Mon Dec 18 2017
Synopsis for the tidal potomac and md portion of the chesapeake bay.. High pressure will control the weather pattern through Tuesday before a cold front crosses the area Tuesday night. High pressure will build to the north Wednesday into Thursday as a front stalls to the south. A small craft advisory may be needed Tuesday night into Wednesday for portions of the waters.

7 Day Forecast for Marine Location Near Grasonville, MD
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location: 38.88, -76.25     debug

Area Discussion for - Philadelphia/Mount Holly, PA
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Fxus61 kphi 180817
area forecast discussion
national weather service mount holly nj
317 am est Mon dec 18 2017

A warm frontal boundary will continue to lift north of the region
today with high pressure building into the southeast united states.

A cold front will then move through the region late Tuesday into
Wednesday. High pressure will then build southeastward into the
region for the middle of the week. On Friday, an area of low
pressure will track northeast into the great lakes bringing a warm
front through our region. This will be followed by a cold frontal
passage at the end of the week or early next week.

Near term until 6 pm this evening
The warm front has been far slower to lift north than previously
expected. As of early this morning, it was still in delmarva. We
still may have a few more hours left for a window of opportunity for
any precip, but thus far radar trends have been underwhelming. There
is very limited, if any, lift associated with the front, and the 00z
iad sounding indicates a very dry boundary layer south of the front.

Once the front lifts north of the area, expect clouds to scatter
out. Agree with the previous shift that the NAM model snow depth is
likely causing a cold bias with temperatures. We should see clearing
skies through the day and temperatures S of the front are already in
the upper 30s and low 40s even as of 2 am. Therefore, trended on the
warmer side of guidance, with forecast highs from the upper 30s
across the southern poconos to lower 50s in S nj and delmarva.

Short term 6 pm this evening through 6 am Tuesday
I am expecting this period to be dry. A few sprinkles are possible
ahead of a surface trough that digs southeast into the great lakes
region, but through the overnight hours, the latest models keep this
trough well to our west. There will be hardly any directional shear,
as flow from the boundary layer through the upper levels will be

Forecast lows are slightly below GFS mos guidance given the light
winds which should promote radiational cooling. However, if low
clouds build in, as one model is depicting, lows may be several
degrees higher. This appears unlikely given the off shore flow.

Long term Tuesday through Sunday
Tuesday through Tuesday night:
our region will be between a high pressure off the southeast
coastline and an approaching cold front from the west. This will
result in southerly winds and warming temperatures. The signal for
precipitation on both the operational runs and ensembles continues
to be fairly limited and confined to locations north and west of
our cwa. Will maintain a precipitation free period. It looks more
like the increase in moisture may just lead to more in the way of
low stratus early Tuesday.

Used a mav ECMWF blend for temperatures, the met guidance looked too
cool because of overdone cloud cover, maybe snow cover mentioned
in short term? Right now the temperature forecast highs on
Tuesday well into the 50's. Nighttime temperatures Tuesday night
should fall back into the 30's.

Wednesday through Thursday night:
after the frontal passage, we return to northwest flow with cold
air advection into the region. Also, with high pressure
building in, both days should be mostly sunny. Another period of
gusty winds is not out of the question. Bufkit analysis shows
the potential for some gusts from the west at around 20 mph
Wednesday afternoon. High temperatures both days should fall
back into the 40's with lows in the 20's, opted to go on the
cooler end of the ensemble guidance given the cold air advection
into the region.

Friday through Sunday night & longer term:
a warm frontal boundary lifts northward across the region as a low
pressure system tracks into the great lakes on Friday. Another surge
of southerly flow and increase in southerly winds will come into the
region leading toward a moderating trend with temperatures, likely
reaching well into the 50's and 60's by Saturday.

A cold frontal boundary will then approach the region from the west
this weekend. The approach of the front has trended slower on the
modeling over the past day or so. However, model and ensemble
solutions have been rather unstable from one run to the next on the

The speed of the this front depends on where the discharge of very
cold air from a -epo goes, most likely into the plains or western
united states at first. A response to this would to increase high
pressure off the east coast which slows the approach of the cold
front and continues to stream warm air northward into the region.

This would result in a large temperature contrast along the frontal
boundary this weekend.

Even with a slower approach, rain chances would enter the picture
either Friday or Friday night and last through much of the weekend.

If the front moves through quicker than forecasted currently,
temperatures would be a good deal cooler with more wintry concerns
(00z GFS 12 18).

Depending on the frontal timing, a non-diurnal temperature is
possible but not included given we are quite a ways away. Modeling
is keying in on the potential for quite a bit of rainfall
potentially with this system, pops were raised to likely on Saturday
where rainfall confidence is highest. Right now, temperatures look
too warm enough to prevent mixing with snow ice on the front
end of the system Friday afternoon and evening.

The large uncertainty with the weekend front would also carry into
christmas as well.

Aviation 08z Monday through Friday
The following discussion is for kphl, kpne, kttn, kabe, krdg,
kilg, kmiv, kacy and surrounding areas.

Today... Once the low clouds over kabe and kttn dissipate (this is
expected to occur before 12z),VFR conditions are expected for the
remainder of the TAF period. Ceilings around or above 5000 ft agl
should scatter out later today. Light and variable winds are
expected through the day. High confidence.

Tonight...VFR conditions are expected. One model is depicting low
clouds developing late tonight, but this appears very unlikely given
the off shore flow. Winds will still be light (less than 10 kt), but
should settle out of the southwest or west by early this evening.

Moderate confidence.


Tuesday through Tuesday night: mainlyVFR, a brief interval of
lower celings possible around sunrise. Wind gusts from the
southwest at 15 knots Tuesday afternoon, decreasing at night.

Moderate confidence.

Wednesday through Friday:VFR. West to northwest wind gusts around
20 knots Wednesday afternoon decreasing gradually into Thursday.

Winds shifting to southeast by Friday but staying near or under 10
knots. Ceilings may start lower later on Friday. High confidence.

Winds and seas are expected to stay below small craft advisory
conditions today and tonight. Wind direction is expected to be
variable, eventually settling out of the west this evening, when a
few gusts near or above 20 kt will be possible.


southwesterly wind gusts of 20-25 knots Tuesday afternoon and
night from the southwest gradually becoming northwest on
Wednesday. For the coastal waters off of northern new jersey,
gusts may be around 25 knots for several hours late Tuesday
night. Gusts decreasing by Wednesday night on all ocean and bay
waters. Data continues to indicate seas stay below five feet
throughout the outlook period. High confidence.

Phi watches warnings advisories
Pa... None.

Nj... None.

De... None.

Md... None.

Marine... None.

Synopsis... Gaines
near term... Gorse johnson
short term... Johnson
long term... Gaines
aviation... Gaines johnson
marine... Gaines johnson

Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
TPLM2 - Thomas Point, MD 10 mi69 min SSE 1.9 G 1.9 42°F 44°F
CPVM2 11 mi51 min 41°F 37°F
APAM2 - 8575512 - Annapolis, MD 14 mi51 min 40°F 1019.5 hPa
TCBM2 - 8573364 - Tolchester Beach, MD 23 mi51 min ESE 1.9 G 2.9 39°F 39°F1020 hPa
CA2 - 8571892 - Cambridge, MD 23 mi57 min 41°F 39°F1020.6 hPa
44062 - Gooses Reef, MD 24 mi39 min SSW 1.9 G 3.9 44°F 1020.4 hPa
BSLM2 - Chesapeake Bay, MD 25 mi159 min Calm 36°F 1020 hPa35°F
FSNM2 28 mi51 min NE 4.1 G 4.1 39°F 1019.2 hPa
FSKM2 - 8574728 - Francis Scott Key Bridge, MD 28 mi51 min NE 1.9 G 2.9 39°F 1019.9 hPa
BLTM2 - 8574680 - Baltimore, MD 32 mi51 min NE 1.9 G 2.9 40°F 45°F1019.5 hPa
COVM2 - 8577018 - Cove Point LNG Pier, MD 34 mi51 min SSW 5.1 G 6 43°F 1020.6 hPa
SLIM2 - 8577330 - Solomons Island, MD 40 mi51 min S 1.9 G 2.9 42°F 44°F1019.6 hPa
WASD2 - 8594900 - Washington, DC 41 mi57 min Calm G 1.9 41°F 40°F1020.1 hPa
DRSD1 - Delaware Reserve, DE 45 mi159 min Calm 39°F 1020 hPa38°F
BISM2 - 8571421 - Bishops Head, MD 47 mi51 min S 2.9 G 2.9 42°F 38°F1020.4 hPa

Wind History for Cambridge, MD
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1 day
2 days

Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Bay Bridge Field, MD8 mi84 minN 07.00 miFog/Mist41°F35°F81%1020 hPa
Easton / Newman Field, MD11 mi72 minN 010.00 miMostly Cloudy42°F35°F80%1021.3 hPa
Annapolis, United States Naval Academy, MD14 mi75 minN 06.00 miFog/Mist41°F39°F93%1020.1 hPa

Wind History from W29 (wind in knots)
Last 24hr--------S3CalmW3NW3NW3SE5SE5S3CalmSE3N4E3S5CalmCalmCalmCalmCalmSE3Calm
1 day ago----------SW9SW14
2 days agoE3----------------------------------------------

Tide / Current Tables for Claiborne, Eastern Bay, Maryland
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Mon -- 01:31 AM EST     New Moon
Mon -- 03:39 AM EST     0.70 feet High Tide
Mon -- 07:18 AM EST     Sunrise
Mon -- 07:20 AM EST     Moonrise
Mon -- 09:38 AM EST     -0.25 feet Low Tide
Mon -- 04:29 PM EST     1.30 feet High Tide
Mon -- 04:45 PM EST     Sunset
Mon -- 05:24 PM EST     Moonset
Mon -- 11:37 PM EST     0.07 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Tide / Current Tables for Baltimore Harbor Approach, Maryland Current
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Baltimore Harbor Approach
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Mon -- 01:31 AM EST     New Moon
Mon -- 03:07 AM EST     0.00 knots Slack
Mon -- 05:32 AM EST     0.49 knots Max Flood
Mon -- 07:19 AM EST     Sunrise
Mon -- 07:21 AM EST     Moonrise
Mon -- 08:07 AM EST     -0.00 knots Slack
Mon -- 10:56 AM EST     -0.56 knots Max Ebb
Mon -- 01:30 PM EST     0.00 knots Slack
Mon -- 04:45 PM EST     Sunset
Mon -- 05:15 PM EST     1.10 knots Max Flood
Mon -- 05:24 PM EST     Moonset
Mon -- 08:41 PM EST     -0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Weather Map and Satellite Images
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Weather Map
IR Satellite Image from GEOS

GOES Local Image of Mid-Atlantic    EDIT

Wind Forecast for Philadelphia/Mount Holly, PA (4,6,7,8)
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Ground Weather Radar Station Dover AFB, DE
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weather_mapweather_map weather_map

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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.