Marine Weather and Tide Forecast for Arden on the Severn, MD

KEY MESSAGES
- 1) Near-record April heat through Thursday as elevated fire weather conditions persist through Saturday.

DISCUSSION
KEY MESSAGE 1...Near-record April heat through Thursday as elevated fire weather conditions persist through Saturday.

A perturbation in the westerly flow aloft is resulting in scattered thunderstorms across the northern quarter of the forecast area this evening. While shear is sufficient for organization, thermodynamic profiles have been a limiting factor for more robust thunderstorms. With nightfall and cooling from the first round of convection a few hours ago, the current storms (and subsequent severe threat) seem to be on a weakening trend. However, subcloud layers are still dry (ceiling heights around 8kft), so gusty winds remain possible. Most of this activity should exit or dissipate by midnight. Any remnants from the thunderstorms over Ohio should remain north. Tonight's forecast lows in the upper 50s to mid 60s are near the average daytime highs for mid April.

Near-record April heat and mostly dry conditions are forecast Wednesday and Thursday. Highs will reach the upper 80s to low 90s across the area both days. Humidity will be on the low side, so heat indices are going to be the same (or lower) than air temperatures.
Still, those who are sensitive to heat should take steps to avoid heat-related illnesses.

There will be showers and thunderstorms in PA tomorrow as another front approaches, but all of the guidance keeps convection north of our area for tomorrow. The next front arrives Thursday night into Friday, but it won't bring any relief from the heat as temps will still be in the 80s Friday. Scattered showers and a few thunderstorms are possible early Friday, but rain amounts will be meager at less than 0.10" for any given area. Saturday looks to be the last day of well above normal temps before a stronger cold front arrives.

A deep upper-level trough centered over the northern Great Plains will form later this week, and will begin to make its way towards the East Coast by late this weekend. The 12z model runs are currently well aligned on a Sunday timeframe for a strong cold front stemming from this trough to track through the Mid-Atlantic. After several days of near-record temperatures in the 80s and 90s, expect a sharp drop in daily highs once this system moves through, with early model runs suggesting a 10-20 degree overall drop in temperatures between Saturday and Monday. Widespread rainfall is likely to accompany this front; thunderstorm chances also return at this time, with ensemble runs showing some convective signatures and NCAR's AI Convective Hazards forecast currently placing the area under a 15-30% likelihood for convection on Sunday. High pressure moves into the area afterwards, allowing for cooler temperatures to persist for a bit once this system moves offshore.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/
Scattered showers and thunderstorms are straddling the MD/PA line this evening. The strongest thunderstorms will likely avoid the terminals, but some showers could affect MRB, BWI, and MTN.
There could also be wind shifts due to outflow. The second half of the night will be dry with light southwest to west winds.

VFR conditions are expected to prevail through at least Saturday morning. Breezy conditions possible each afternoon, with south to southwest winds gusting around 20-25 knots for several hours. A few thunderstorms are possible this evening, and again Thursday night into Friday, but coverage and impacts are forecast to be low.

MARINE
Extended the Small Craft Advisory until midnight for the wider mid-Bay waters where some southwesterly gusts to around 20 kt continue this evening. Otherwise light winds should prevail through the night.

SCA conditions are possible each afternoon through Saturday as southerly channeling produces a few hours of wind gusts around 20 knots. Outside of that, winds remain generally at or below 10 knots.
Some thunderstorms will be possible Thursday night into Friday, then again over the weekend as cold fronts track through the area.

FIRE WEATHER
Elevated fire weather conditions are likely to continue across most of the area through Saturday. Each afternoon will bring well above normal temperatures in the 80s to low 90s, southwest winds gusting around 20-25 mph, and minimum RH values around 25-35 percent. Fire weather SPSs will likely be needed each day, with coordination from local fire partners and surrounding NWS offices to hone in on areas that are most sensitive. The ongoing lack of rain is going to continue to dry fine fuels, with fuel moistures decreasing a bit each successive day. Local showers and thunderstorms which have occurred across portions of northern Maryland and eastern West Virginia may provide a bit of reprieve in those areas.

Thursday looks to be the most fire sensitive day due to a combination of RH values around 20-30 percent and wind gust around 20-25 mph in the afternoon. There is the potential for very dry air to mix down to the surface, this could possibly drop RH values below 20 percent in some areas. If these low RH values come to fruition, it is possible we could be close to Red Flag conditions.

Scattered showers and thunderstorms are possible Thursday night into Friday, but coverage will be too low for any beneficial wetting rain. A strong cold front is set to cross the area Sunday, with cooler temperatures into next week. However, there is uncertainty regarding whether most of the area sees a wetting rain, it could be limited rainfall from this front.

CLIMATE
Many daily records are likely to be broken this week, for both high temperatures and warm low temperatures. Some stations could tie or set their all-time high temperature and warm low temperature records for the month of April.

April 14 Location RECORD HIGH RECORD WARM LOW Washington-National (DCA) 91F (1960) 65F (2014)
Washington-Dulles (IAD) 87F (1960) 63F (2014)
Baltimore (BWI) 91F (1941) 65F (2018)
Baltimore Inner Harbor (DMH) 90F (1960) 67F (2018)
Martinsburg (MRB) 87F (1960) 62F (2014)
Charlottesville (CHO) 90F (1945) 67F (1899)
Annapolis(NAK) 90F (1941) 65F (1977)
Hagerstown (HGR) 86F (2024) 64F (2014)

April 15 Location RECORD HIGH RECORD WARM LOW Washington-National (DCA) 89F (1941) 65F (2023)
Washington-Dulles (IAD) 87F (1967) 62F (2023)
Baltimore (BWI) 88F (1941) 65F (1941)
Baltimore Inner Harbor (DMH) 92F (2024) 67F (1960)
Martinsburg (MRB) 90F (1941) 63F (1967)
Charlottesville (CHO) 92F (2024) 68F (1941)
Annapolis(NAK) 91F (1941) 68F (1994)
Hagerstown (HGR) 85F (1960) 61F (2023)

April 16 Location RECORD HIGH RECORD WARM LOW Washington-National (DCA) 92F (2002) 65F (2017)
Washington-Dulles (IAD) 91F (2002) 63F (2017)
Baltimore (BWI) 90F (2012) 66F (1941)
Baltimore Inner Harbor (DMH) 91F (2012) 65F (2012)
Martinsburg (MRB) 90F (2002) 63F (2017)
Charlottesville (CHO) 92F (1976) 67F (1941)
Annapolis(NAK) 89F (2017) 70F (1994)
Hagerstown (HGR) 88F (2002) 62F (2002)

April 17 Location RECORD HIGH RECORD WARM LOW Washington-National (DCA) 95F (2002) 65F (2002)
Washington-Dulles (IAD) 93F (2002) 59F (2024)
Baltimore (BWI) 93F (2002) 66F (1896)
Baltimore Inner Harbor (DMH) 95F (2002) 66F (1976)
Martinsburg (MRB) 93F (2002) 60F (1941)
Charlottesville (CHO) 94F (1976) 65F (1976)
Annapolis(NAK) 90F (1976) 68F (1994)
Hagerstown (HGR) 90F (2002) 64F (2002)

All-Time April Record Highs: Washington-National (DCA) 95F 4/17/2002, 4/18/1976, 4/23/1960 4/27/1915 Washington-Dulles (IAD) 93F 4/6/2010, 4/17/2002, 4/25/1960 Baltimore (BWI) 94F 4/25/1960, 4/23/1960, 4/20/1941, 4/18/1896 Baltimore Inner Harbor (DMH) 98F 4/26/1990, 4/22/1985 Martinsburg (MRB) 96F 4/21/1941 Charlottesville (CHO) 98F 4/24-25/1925 Annapolis(NAK) 95F 4/20/1941 Hagerstown (HGR) 94F 4/6/2010, 4/18/1976, 4/26/1915

All-Time April Record Warm-Lows: Washington-National (DCA) 70F 4/29/2017 Washington-Dulles (IAD) 68F 4/27/2011 Baltimore (BWI) 70F 4/19/1896 Baltimore Inner Harbor (DMH) 76F 4/26/1990 Martinsburg (MRB) 69F 4/19/2025 Charlottesville (CHO) 72F 4/26/1915 Annapolis(NAK) 70F 4/28/1994, 4/16/1994, 4/18/1896 Hagerstown (HGR) 69F 4/27/2009

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until midnight EDT tonight for ANZ534-543.