Chesapeake Bay From Pooles Island to Sandy Point MD Marine Forecast
| Rest Of This Afternoon...Sw Winds 10 Kt. Waves 1 Ft. |
| Tonight...W Winds 5 To 10 Kt...Becoming N Late. Waves 1 Ft. |
| Thu...Nw Winds Around 5 Kt...Becoming Sw Late. Waves 1 Ft. Areas Of Smoke. |
| Thu Night...W Winds 5 To 10 Kt...Becoming N After Midnight. Waves 1 Ft. Areas Of Smoke. |
| Fri...N Winds 5 To 10 Kt...Becoming Se In The Afternoon. Waves 1 Ft. Areas Of Smoke. |
| Fri Night...Se Winds 5 To 10 Kt. Waves 1 Ft. |
| Sat...S Winds 5 To 10 Kt. Waves 1 To 2 Ft. Showers With Tstms Likely. |
| Sun...Nw Winds 5 To 10 Kt...Becoming Ne After Midnight. Waves 1 Ft. A Chance Of Showers In The Morning, Then A Chance Of Showers And Tstms Through The Night. Winds And Waves Higher And Visibilities Lower In And Near Tstms. |
| Area Forecast Discussion National Weather Service Baltimore MD/Washington DC 329pm EDT Wednesday July 15 2026 .WHAT HAS CHANGED... Have held off on any Heat Advisories for Thursday due to uncertainties in both humidity and smoke affecting temperatures and heat index values. So far today, temperatures have been a bit slower to rise and dew points a bit slower to fall, resulting in heat index values around where they were expected to be. Added a slight chance of thunderstorms Thursday late afternoon and evening across northern and eastern areas due to a weak cold front dropping in. .KEY MESSAGES... - 1) Heat continues through Friday. - 2) Thunderstorm chances increase this weekend and could potentially linger into early next week as a front drops into the region. KEY MESSAGE 1...Heat continues through Friday. Although temperatures will likely peak this afternoon, above normal temperatures will persist through Friday. The 12Z KIAD RAOB (Radiosonde Observation or Upper-Air Observation) showed 850 hPa temps around 23 C, a pinch higher than they were during the heat wave earlier this month. Recent NUCAPS data from 18Z shows 925 hPa temps around 30 C which if mixed dry adiabatically to the surface would result in temps in the lower 100s. Mixing has been a bit subdued so far today due to thin smoke aloft, similar to how mixing is limited in the presence of a Saharan Air (Dust) Layer. This has also held dew points up in the upper 60s to lower 70s, highest northeast of the Potomac River where latest NUCAPS data shows a relative max in 850 hPa Tds. It is possible that areas of even slightly deeper mixing could see surface temps jump several degrees through late afternoon (with a corresponding drop in dew points). Either way, the heat index values will remain the same - generally 100 to 105 (slightly higher east of I-95). There is uncertainty in just how high temperatures get both Thursday and especially Friday as smoke from wildfires over Canada continues to trek toward the Mid-Atlantic. There are also questions around how much dew points mix out Thursday afternoon in particular, so have held off on any additional headlines. Of note, the RRFS-A may be onto something in how it resolves the incoming smoke with slightly lower air temps and higher dew points the next few days when compared to other guidance. After similar temperatures Thursday, lowering thicknesses and increasing smoke aloft support the idea of temperatures being several degrees lower on Friday. The forecast may need to be lowered further if smoke is thicker, or a passing weak cold front is a bit stronger/pushes further south. KEY MESSAGE 2...Thunderstorm chances increase this weekend and could potentially linger into early next week as a front drops into the region. Ample subsidence and dry air aloft are expected to start the day on Thursday. Height falls/PVA will be negligible as most forcing for ascent will be associated with shortwaves in cyclonic flow passing to the north and northeast. However, a halt in height rises paired with a slowly southward sagging cold front and potentially bay breezes in areas where low-level flow goes weak in the vicinity of the front, may be enough when coupled with heating to result in a couple of isolated thunderstorms. There is further uncertainty given continued smoke aloft, as that could hamper heating and instability/convective initiation. Upstream over NE PA into NJ and the NYC tri-state area may offer a clue this afternoon as we will be in a similar environment across the MD/PA border tomorrow afternoon. Any storms that manage to develop will have ample MLCAPE (2000-3000 J/kg) and DCAPE (1000-1500 J/kg) to work with, as well as notable flow in the mid and upper levels for mid July (40-50+ kts). If any storms manage to develop by late afternoon, they could at least briefly congeal into a small cluster and propagate south/ southeast toward and across the Chesapeake Bay during the evening hours. Damaging winds would be the primary (conditional) risk, but large hail is also possible given ample CAPE, shear, and low seasonably low wet-bulb zero heigheights around 11.5 kft. The surface front will drop further southward Friday. Additional smoke likely mixes into the region. Any convection on Friday will likely be limited to the higher terrain as the front washes out and pairs with orographic lift. Again, any storm that does form could be on the strong side. Friday night, the aforementioned front will begin to lift north ahead of a wave of low pressure and stout shortwave approaching from the Upper Midwest/Great Lakes. Increasing MLCAPE late at night with some moisture advection and modest low-level flow overtop the front may result in a few thunderstorms heading into early Saturday morning, especially east of the Blue Ridge where a bit richer low-level theta-e ridge looks to pivot through. Forcing and shear will be ample on Saturday, but the amount of instability is in question due to potential morning precip. Should enough instability develop, severe weather is certainly possible with all hazards (damaging straight-line winds, large hail, a few tornadoes, and isolated instances of flash flooding) on the table. If the front does not make it entirely through the area, repeated strong storms will be possible on Sunday. After a brief lull possible on Monday, another strong wave may approach by mid week next week. Marine Winds will waver between N/NW and SW over the next few days as a cold front dangles near the waters. Depending on the strength of the front and how far north or south it pushes, there may be at least brief/marginal periods of SCA (Small Craft Advisory) level gusts, though these currently appear too brief with certainty too low for any headlines at the moment. A couple of thunderstorms can't be ruled out along the cold front Thursday late afternoon and evening, and anything that does manage to form could produce rather gusty winds. Waves of showers and thunderstorms are anticipated this weekend. Special Marine Warnings may be needed in stronger convection. Climate Well above normal temperatures will persist through Thursday. Below is a list of record daily high and warm low temperatures for July 15 (Wednesday) and July 16 (Thursday). ================================================================= July 15 Record Daily High/Warm Low Temperatures ================================================================= Baltimore MD 102 (2024, 1995) 79 (1995, 1936) Washington DC 102 (2024) 81 (2024) Sterling-Dulles Airport VA 99 (2024) 75 (2024) Baltimore (Downtown) MD 101 (2024) 85 (1988) Annapolis MD 101 (1995) 81 (1896) Hagerstown MD 102 (1954) 78 (2024) Martinsburg WV 107 (1936) 75 (1995) Charlottesville VA 102 (1954) 76 (1936) ================================================================= July 16 Record Daily High/Warm Low Temperatures ================================================================= Baltimore MD 104 (2024, 1988) 78 (1879) Washington DC 104 (2024, 1988) 84 (1983) Sterling-Dulles Airport VA 104 (1988) 74 (2013) Baltimore (Downtown) MD 105 (2024) 85 (2013) Annapolis MD 98 (1997, 1900) 79 (2024, 2013, 1955) Hagerstown MD 104 (1988) 76 (2024) Martinsburg WV 107 (1988) 77 (1983) Charlottesville VA 102 (1988) 82 (1983) Period of Record (POR) information (records since): Baltimore MD - July 1872 Washington DC - January 1872 Sterling - Dulles Airport VA - January 1960 Baltimore (Downtown) MD - July 1950 Annapolis MD - January 1894 Hagerstown MD - January 1899 Martinsburg WV - January 1891 Charlottesville VA - January 1893 NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories DC... Heat Advisory until 8pm EDT this evening for DCZ001. MD... Heat Advisory until 8pm EDT this evening for MDZ003>006-008- 011-013-014-016>018-502>508. VA... Heat Advisory until 8pm EDT this evening for VAZ026>031-040- 051-053>057-501-502-505-506-526-527. WV... Heat Advisory until 8pm EDT this evening for WVZ050>053-055- 502-504. Marine None. |
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