Marine Weather and Tide Forecast for Williamsport, MD
May 17, 2024 1:22 PM EDT (17:22 UTC) Change Location
 | Sunrise 5:52 AM Sunset 8:22 PM Moonrise 1:47 PM Moonset 2:08 AM |
ANZ535 Tidal Potomac From Key Bridge To Indian Head- 1034 Am Edt Fri May 17 2024
Rest of today - E winds 5 kt. Waves less than 1 ft. Isolated showers this afternoon.
Tonight - SE winds 5 to 10 kt. Waves 1 ft. Showers likely.
Sat - E winds 5 to 10 kt. Waves 1 ft. Showers likely.
Sat night - E winds 5 to 10 kt. Waves 1 ft. A chance of showers.
Sun - NE winds 5 to 10 kt. Waves 1 ft. A chance of showers.
Sun night - E winds 5 to 10 kt. Waves 1 ft.
Mon - E winds around 5 kt. Waves 1 ft.
Tue - SE winds around 5 kt. Waves 1 ft.
ANZ500 1034 Am Edt Fri May 17 2024
Synopsis for the tidal potomac and md portion of the chesapeake bay -
marine conditions will gradually deteriorate later today and into the weekend as low pressure passes south of the waters. High pressure will build over the waters on Monday and Tuesday, before a strong cold front approaches during the middle of the week. Small craft advisories may be needed for portions of the waters on Saturday and Sunday.
marine conditions will gradually deteriorate later today and into the weekend as low pressure passes south of the waters. High pressure will build over the waters on Monday and Tuesday, before a strong cold front approaches during the middle of the week. Small craft advisories may be needed for portions of the waters on Saturday and Sunday.
Area Discussion for - Baltimore, MD/Washington
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FXUS61 KLWX 171428 AFDLWX
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1028 AM EDT Fri May 17 2024
SYNOPSIS
An area of low pressure will approach from the south and west later today bringing renewed chances for showers and thunderstorms.
Widespread rain and thunderstorm activity is expected Saturday into Sunday as low pressure pushes towards the Carolina coast. Drier conditions with a slight warming trend are expected Monday and Tuesday as high pressure pushes back into the region. A potent cold front looks to bring additional showers and thunderstorms to the area by the middle of next week.
NEAR TERM /THROUGH TONIGHT/
Mid-morning update: Conditions remain dry across the forecast area to start the day. However, coverage of low-level stratus has increased in response to daytime mixing to the east of the Blue Ridge. Further west, mid-high level clouds have increased, leaving pretty much all of the forecast area cloudy as of 10 AM.
Rain is slowly spreading eastward across western PA and WV, and should make it into far northwestern portions of the forecast area around noon. Flooding remains the main concern this afternoon into tonight, with the primary focus of heavier rains still expected to be across the Potomac Highlands, Shenandoah Valley, and Central Virginia. A slight north/westward expansion of the current Flood Watch is being considered at the moment, and a final decision will be made over the next 1-2 hours after all of the incoming 12z CAM guidance is evaluated. Previous discussion follows...
It's a dry start for many this morning. Showers and thunderstorms will be on the increase this afternoon and evening to the west of the Blue Ridge, and eventually into central Virginia. Some minor flooding issues are possible especially in areas that due see repetitive rounds of slow moving convection.
This is especially a concern for portions of the Potomac Highlands (Hardy and Hampshire counties in WV) southward into the Shenandoah Valley and central VA (Rockingham, Madison, Nelson, Augusta, and Albermarle counties). Current CAMS (HRRR, RRFS, ARW, HRRR and FV3)
and 00z synoptic(NAM/GFS/ICON) guidance continues to paint a bullseye of 2-4" of rain across the Potomac/Allegheny Highlands south and east toward the central/southern Shenandoah Valley. 3-6 hour flash flood guidance in these areas sits between 2-3 inches with 1.5-2 inch values across the urban centers (i.e Harrisonburg, Waynesboro, Staunton, and Charlottesville). With all that said, WPC has highlighted this area in a Slight Risk for excessive rainfall within the Day 1 outlook
Given the consistency will go forth with a Flood Watch to encompass the threat later this afternoon and evening. Saturation of column (i.e PWATS around 1.5-1.7"), training convection, terrain, and consistency amongst guidance further confidence for the watch issuance. Any convection should wane as we head into the late evening and overnight hours. Light to moderate rain will remain as shortwave energy pivots east and the incumbent upper level low approaches from the Tennessee River Valley/southern Appalachians region.
High temperatures today will be slightly cooler in the upper 60s and low to mid 70s under increased cloud cover. The warmer air will be down across central and southwest VA where a few breaks in the clouds will occur through midday before filling in this afternoon.
Lows tonight will fall into the mid to upper 50s.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
It's another stormy and soggy weekend ahead across much of the Mid- Atlantic region. This marks our 2nd weekend in row during the month of May and 4th weekend since mid/late April for wet weekend weather.
Once again an upper level trough and slow moving low pressure system are to blame for the increased precipitation chances across the region.
By Saturday, the resultant upper level low pressure system will be ejecting out Tennessee River Valley and toward the Carolina coastline Saturday night into Sunday. Ample moisture will continue to advect in off the Atlantic ahead of low on southeast flow. This will aid in a bit more stability during the afternoon and evening hours especially along and north of I-66/US-50. Even with that said, numerous to widespread showers and thunderstorms are likely late Saturday morning and into Saturday afternoon. The highest likelihood for thunderstorms looks again to be confined to areas south of I- 66/US-50 and in particularly south of I-64 due to the proximity of the upper level low. Severe weather does not appear to be a concern at this point given limited CAPE and shear with ample cloud cover overhead. Localized flooding will remain a concern given repetitive rounds of heavy rain from Friday and rich moisture (high PWATS)funneling in. Some locations could see one to two inches of rain with locally higher amounts throughout the weekend period. WPC and CSU learning probabilities continue to highlight the area in a Marginal Risk for excessive rainfall per the Day 2 outlook. Highest rain totals will be confined to areas along and west of the Blue Ridge and back across the central/southern VA Piedmont.
The upper level low pressure will scoot south of the region Saturday night into Sunday. This will allow for north to northeast flow to advect slightly drier air down the spine of Appalachian Mountains.
Shower and thunderstorm coverage and intensity will decrease as result.
Shower chances continue into Sunday although coverage will become a bit more scattered throughout the day as low pressure pulls away from the region. Highest probabilities for showers will be across central and southern portions of the forecast area with sprinkles/drizzle further north. Rain chances finally diminish Sunday night as drier air filters in. Temperatures were kept to the cooler side of model guidance due to the abundant cloud cover and ongoing chances of showers and thunderstorms Highs will struggle to get out of the mid to upper 60s (low 60s across the PA/MD line and mountains) Saturday afternoon. Lows Saturday and Sunday nights will fall back into the low to mid 50s.
LONG TERM /MONDAY THROUGH THURSDAY/
To start off the work week, a positively-tilted southern stream trough should slowly pull away from the Carolina coast. The resultant surface pattern does maintain low pressure off the Carolinas and high pressure across the northeastern U.S.
Consequently, a net easterly onshore flow is maintained which does keep temperatures slightly below average on Monday. However, a broad mid/upper level ridge eventually settles over the Eastern Seaboard through roughly mid-week. The building of heights will allow for a marked warm up as high temperatures return to the low/mid 80s by Wednesday. Ample subsidence underneath this ridge should squash any shower chances through Tuesday. As return flow increases by mid- week, humidity levels begin to creep back up as dew points rise into the low/mid 60s by Wednesday.
A frontal system approaching from the west will increase shower and thunderstorm chances by mid-week. The net result of warming temperatures and increasing humidity levels should raise surface- based CAPE values to around 1,000 J/kg or so. This increasingly unstable air mass may interact with a series of perturbations tracking through in the southwesterly flow aloft. While global models struggle to capture convective processes this far out in time, the overall signal and pattern recognition suggests an increasingly convective pattern. The approaching cold front is not slated to pass through the local area until late Wednesday. Thus, any convective threats could fester into the overnight hours. In the wake, expect drier conditions into Thursday, but with similar temperatures. Ensemble systems do agree on decreasing humidity owing to the shift to west-northwesterly flow on Thursday.
AVIATION /14Z FRIDAY THROUGH TUESDAY/
Currently sandwiched between an increasing stratus deck advecting in off the Atlantic and mid/high level clouds pushing in from the Ohio/Tennessee River Valley ahead of an approaching low pressure set to impact the area this weekend. Predominantly MVFR conditions are expected across the terminals this morning with intermittent pockets of IFR scattered across mountain terminals and terminals close to large bodies of water.
VFR to MVFR cigs will start the afternoon before deteriorating flight conditions move in late afternoon and into the evening hours. Any shower and thunderstorm activity should be relegated to terminals west of a line from KMRB south to KCHO/KSHD beyond 18z/2pm this afternoon. As for the corridor itself, any thunderstorm activity should wane as precipitation moves east. Did leave a mention of VCTS in at KIAD with the higHer confidence toward KCHO/KSHD/KHGR/KMRB later this afternoon and into the late evening hours.
MVFR to IFR conditions are expected tonight as widespread light to moderate rain overspreads the terminals. Sub-VFR conditions will continue through much of Saturday into Saturday night as numerous showers and thunderstorms pass across the region. This is due in part to an upper level low pressure system that will push off the Carolina coast Sunday. Additional MVFR/IFR conditions will likely remain during this time period.
Winds will remain light out of the north/northeast this morning switching to the southeast this afternoon and evening. Winds will turn toward the east Saturday before switching back to the north and northeast Sunday. Speeds of 5 to 15 kts are expected through the weekend period.
Depending on how long the easterly onshore flow keeps marine stratus in the picture, the D.C. and Baltimore terminals could see MVFR ceilings to start off the day on Monday. Expect improving conditions for the second half of the day and into Tuesday. A period of VFR conditions are likely through Tuesday, accompanied by dry weather and a shift from east to southeasterly winds.
MARINE
Lighter winds are expected today out of the northeast switching to the southeast this afternoon as weak high pressure pushes off the southeast U.S coast.
SCA conditions return Saturday under increased onshore east to northeast flow. Low pressure will pass south of the waters Saturday night into Sunday leading to a continuation of SCA conditions. This will be especially true over middle and lower portions of the bay and lower tidal Potomac where a bit more of the gradient winds will be realized. Numerous showers and perhaps a few thunderstorms will accompany this system Saturday into early Sunday. Winds Saturday night into Sunday will gradually shift to north-northeasterly as the low slides south of the region. Northeasterly winds diminish Sunday night and become light and southeasterly heading into Monday afternoon and evening.
The relatively tight gradient formed by low pressure off the Carolina coast and high pressure over the northeastern U.S. may keep small craft conditions in place for Monday. This is especially the case over the more southern waters. Such gradients weaken into Monday evening/night and Tuesday. Initial easterly flow gives way to southeasterly winds by Tuesday, accompanied by gusts staying under 15 knots.
TIDES/COASTAL FLOODING
Persistent onshore flow will continue through early next week.
This will result in elevated tide levels. Minor flooding is expected in more sensitive locations over the next several tidal cycles.
LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...Coastal Flood Advisory until 7 AM EDT Saturday for MDZ014.
Coastal Flood Advisory until 2 AM EDT Saturday for MDZ017-018.
VA...Flood Watch from 3 PM EDT this afternoon through late tonight for VAZ025>027-029-030-036>040-050-051-504-507-508.
WV...Flood Watch from 3 PM EDT this afternoon through late tonight for WVZ055-506.
MARINE...None.
Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 1028 AM EDT Fri May 17 2024
SYNOPSIS
An area of low pressure will approach from the south and west later today bringing renewed chances for showers and thunderstorms.
Widespread rain and thunderstorm activity is expected Saturday into Sunday as low pressure pushes towards the Carolina coast. Drier conditions with a slight warming trend are expected Monday and Tuesday as high pressure pushes back into the region. A potent cold front looks to bring additional showers and thunderstorms to the area by the middle of next week.
NEAR TERM /THROUGH TONIGHT/
Mid-morning update: Conditions remain dry across the forecast area to start the day. However, coverage of low-level stratus has increased in response to daytime mixing to the east of the Blue Ridge. Further west, mid-high level clouds have increased, leaving pretty much all of the forecast area cloudy as of 10 AM.
Rain is slowly spreading eastward across western PA and WV, and should make it into far northwestern portions of the forecast area around noon. Flooding remains the main concern this afternoon into tonight, with the primary focus of heavier rains still expected to be across the Potomac Highlands, Shenandoah Valley, and Central Virginia. A slight north/westward expansion of the current Flood Watch is being considered at the moment, and a final decision will be made over the next 1-2 hours after all of the incoming 12z CAM guidance is evaluated. Previous discussion follows...
It's a dry start for many this morning. Showers and thunderstorms will be on the increase this afternoon and evening to the west of the Blue Ridge, and eventually into central Virginia. Some minor flooding issues are possible especially in areas that due see repetitive rounds of slow moving convection.
This is especially a concern for portions of the Potomac Highlands (Hardy and Hampshire counties in WV) southward into the Shenandoah Valley and central VA (Rockingham, Madison, Nelson, Augusta, and Albermarle counties). Current CAMS (HRRR, RRFS, ARW, HRRR and FV3)
and 00z synoptic(NAM/GFS/ICON) guidance continues to paint a bullseye of 2-4" of rain across the Potomac/Allegheny Highlands south and east toward the central/southern Shenandoah Valley. 3-6 hour flash flood guidance in these areas sits between 2-3 inches with 1.5-2 inch values across the urban centers (i.e Harrisonburg, Waynesboro, Staunton, and Charlottesville). With all that said, WPC has highlighted this area in a Slight Risk for excessive rainfall within the Day 1 outlook
Given the consistency will go forth with a Flood Watch to encompass the threat later this afternoon and evening. Saturation of column (i.e PWATS around 1.5-1.7"), training convection, terrain, and consistency amongst guidance further confidence for the watch issuance. Any convection should wane as we head into the late evening and overnight hours. Light to moderate rain will remain as shortwave energy pivots east and the incumbent upper level low approaches from the Tennessee River Valley/southern Appalachians region.
High temperatures today will be slightly cooler in the upper 60s and low to mid 70s under increased cloud cover. The warmer air will be down across central and southwest VA where a few breaks in the clouds will occur through midday before filling in this afternoon.
Lows tonight will fall into the mid to upper 50s.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
It's another stormy and soggy weekend ahead across much of the Mid- Atlantic region. This marks our 2nd weekend in row during the month of May and 4th weekend since mid/late April for wet weekend weather.
Once again an upper level trough and slow moving low pressure system are to blame for the increased precipitation chances across the region.
By Saturday, the resultant upper level low pressure system will be ejecting out Tennessee River Valley and toward the Carolina coastline Saturday night into Sunday. Ample moisture will continue to advect in off the Atlantic ahead of low on southeast flow. This will aid in a bit more stability during the afternoon and evening hours especially along and north of I-66/US-50. Even with that said, numerous to widespread showers and thunderstorms are likely late Saturday morning and into Saturday afternoon. The highest likelihood for thunderstorms looks again to be confined to areas south of I- 66/US-50 and in particularly south of I-64 due to the proximity of the upper level low. Severe weather does not appear to be a concern at this point given limited CAPE and shear with ample cloud cover overhead. Localized flooding will remain a concern given repetitive rounds of heavy rain from Friday and rich moisture (high PWATS)funneling in. Some locations could see one to two inches of rain with locally higher amounts throughout the weekend period. WPC and CSU learning probabilities continue to highlight the area in a Marginal Risk for excessive rainfall per the Day 2 outlook. Highest rain totals will be confined to areas along and west of the Blue Ridge and back across the central/southern VA Piedmont.
The upper level low pressure will scoot south of the region Saturday night into Sunday. This will allow for north to northeast flow to advect slightly drier air down the spine of Appalachian Mountains.
Shower and thunderstorm coverage and intensity will decrease as result.
Shower chances continue into Sunday although coverage will become a bit more scattered throughout the day as low pressure pulls away from the region. Highest probabilities for showers will be across central and southern portions of the forecast area with sprinkles/drizzle further north. Rain chances finally diminish Sunday night as drier air filters in. Temperatures were kept to the cooler side of model guidance due to the abundant cloud cover and ongoing chances of showers and thunderstorms Highs will struggle to get out of the mid to upper 60s (low 60s across the PA/MD line and mountains) Saturday afternoon. Lows Saturday and Sunday nights will fall back into the low to mid 50s.
LONG TERM /MONDAY THROUGH THURSDAY/
To start off the work week, a positively-tilted southern stream trough should slowly pull away from the Carolina coast. The resultant surface pattern does maintain low pressure off the Carolinas and high pressure across the northeastern U.S.
Consequently, a net easterly onshore flow is maintained which does keep temperatures slightly below average on Monday. However, a broad mid/upper level ridge eventually settles over the Eastern Seaboard through roughly mid-week. The building of heights will allow for a marked warm up as high temperatures return to the low/mid 80s by Wednesday. Ample subsidence underneath this ridge should squash any shower chances through Tuesday. As return flow increases by mid- week, humidity levels begin to creep back up as dew points rise into the low/mid 60s by Wednesday.
A frontal system approaching from the west will increase shower and thunderstorm chances by mid-week. The net result of warming temperatures and increasing humidity levels should raise surface- based CAPE values to around 1,000 J/kg or so. This increasingly unstable air mass may interact with a series of perturbations tracking through in the southwesterly flow aloft. While global models struggle to capture convective processes this far out in time, the overall signal and pattern recognition suggests an increasingly convective pattern. The approaching cold front is not slated to pass through the local area until late Wednesday. Thus, any convective threats could fester into the overnight hours. In the wake, expect drier conditions into Thursday, but with similar temperatures. Ensemble systems do agree on decreasing humidity owing to the shift to west-northwesterly flow on Thursday.
AVIATION /14Z FRIDAY THROUGH TUESDAY/
Currently sandwiched between an increasing stratus deck advecting in off the Atlantic and mid/high level clouds pushing in from the Ohio/Tennessee River Valley ahead of an approaching low pressure set to impact the area this weekend. Predominantly MVFR conditions are expected across the terminals this morning with intermittent pockets of IFR scattered across mountain terminals and terminals close to large bodies of water.
VFR to MVFR cigs will start the afternoon before deteriorating flight conditions move in late afternoon and into the evening hours. Any shower and thunderstorm activity should be relegated to terminals west of a line from KMRB south to KCHO/KSHD beyond 18z/2pm this afternoon. As for the corridor itself, any thunderstorm activity should wane as precipitation moves east. Did leave a mention of VCTS in at KIAD with the higHer confidence toward KCHO/KSHD/KHGR/KMRB later this afternoon and into the late evening hours.
MVFR to IFR conditions are expected tonight as widespread light to moderate rain overspreads the terminals. Sub-VFR conditions will continue through much of Saturday into Saturday night as numerous showers and thunderstorms pass across the region. This is due in part to an upper level low pressure system that will push off the Carolina coast Sunday. Additional MVFR/IFR conditions will likely remain during this time period.
Winds will remain light out of the north/northeast this morning switching to the southeast this afternoon and evening. Winds will turn toward the east Saturday before switching back to the north and northeast Sunday. Speeds of 5 to 15 kts are expected through the weekend period.
Depending on how long the easterly onshore flow keeps marine stratus in the picture, the D.C. and Baltimore terminals could see MVFR ceilings to start off the day on Monday. Expect improving conditions for the second half of the day and into Tuesday. A period of VFR conditions are likely through Tuesday, accompanied by dry weather and a shift from east to southeasterly winds.
MARINE
Lighter winds are expected today out of the northeast switching to the southeast this afternoon as weak high pressure pushes off the southeast U.S coast.
SCA conditions return Saturday under increased onshore east to northeast flow. Low pressure will pass south of the waters Saturday night into Sunday leading to a continuation of SCA conditions. This will be especially true over middle and lower portions of the bay and lower tidal Potomac where a bit more of the gradient winds will be realized. Numerous showers and perhaps a few thunderstorms will accompany this system Saturday into early Sunday. Winds Saturday night into Sunday will gradually shift to north-northeasterly as the low slides south of the region. Northeasterly winds diminish Sunday night and become light and southeasterly heading into Monday afternoon and evening.
The relatively tight gradient formed by low pressure off the Carolina coast and high pressure over the northeastern U.S. may keep small craft conditions in place for Monday. This is especially the case over the more southern waters. Such gradients weaken into Monday evening/night and Tuesday. Initial easterly flow gives way to southeasterly winds by Tuesday, accompanied by gusts staying under 15 knots.
TIDES/COASTAL FLOODING
Persistent onshore flow will continue through early next week.
This will result in elevated tide levels. Minor flooding is expected in more sensitive locations over the next several tidal cycles.
LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...Coastal Flood Advisory until 7 AM EDT Saturday for MDZ014.
Coastal Flood Advisory until 2 AM EDT Saturday for MDZ017-018.
VA...Flood Watch from 3 PM EDT this afternoon through late tonight for VAZ025>027-029-030-036>040-050-051-504-507-508.
WV...Flood Watch from 3 PM EDT this afternoon through late tonight for WVZ055-506.
MARINE...None.
toggle option: (graph/table)
| Airport | Dist | Age | Wind kt | Vis | Sky | Weather | Temp | DewPt | RH | inHg |
| KHGR HAGERSTOWN RGNLRICHARD A HENSON FLD,MD | 10 sm | 29 min | ESE 05 | 10 sm | Overcast | 66°F | 57°F | 73% | 29.97 | |
| KMRB EASTERN WV RGNL/SHEPHERD FLD,WV | 15 sm | 29 min | calm | 10 sm | Overcast | 64°F | 57°F | 77% | 29.95 |
Tide / Current data from XTide NOT FOR NAVIGATION
Chain Bridge, Washington, D.C., Tide feet
Chain Bridge
Click for Map
Fri -- 03:05 AM EDT Moonset
Fri -- 04:58 AM EDT 3.01 feet High Tide
Fri -- 05:53 AM EDT Sunrise
Fri -- 11:21 AM EDT 0.69 feet Low Tide
Fri -- 02:44 PM EDT Moonrise
Fri -- 05:19 PM EDT 2.85 feet High Tide
Fri -- 08:16 PM EDT Sunset
Fri -- 11:38 PM EDT 0.60 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Click for Map
Fri -- 03:05 AM EDT Moonset
Fri -- 04:58 AM EDT 3.01 feet High Tide
Fri -- 05:53 AM EDT Sunrise
Fri -- 11:21 AM EDT 0.69 feet Low Tide
Fri -- 02:44 PM EDT Moonrise
Fri -- 05:19 PM EDT 2.85 feet High Tide
Fri -- 08:16 PM EDT Sunset
Fri -- 11:38 PM EDT 0.60 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Chain Bridge, D.C., Tide feet
| 12 am |
| 0.8 |
| 1 am |
| 1.4 |
| 2 am |
| 2 |
| 3 am |
| 2.5 |
| 4 am |
| 2.9 |
| 5 am |
| 3 |
| 6 am |
| 2.8 |
| 7 am |
| 2.3 |
| 8 am |
| 1.8 |
| 9 am |
| 1.3 |
| 10 am |
| 0.9 |
| 11 am |
| 0.7 |
| 12 pm |
| 0.8 |
| 1 pm |
| 1.1 |
| 2 pm |
| 1.7 |
| 3 pm |
| 2.3 |
| 4 pm |
| 2.6 |
| 5 pm |
| 2.8 |
| 6 pm |
| 2.8 |
| 7 pm |
| 2.4 |
| 8 pm |
| 1.8 |
| 9 pm |
| 1.3 |
| 10 pm |
| 0.9 |
| 11 pm |
| 0.7 |
Sterling, VA,
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