Marine Weather and Tide Forecast for Calvert Beach, MD

KEY MESSAGES
- 1) Heat Advisories have been issued for most of the area today as records are challenged. 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.

DISCUSSION
KEY MESSAGE 1...Heat Advisories have been issued for most of the area today as records are challenged. Heat continues through Friday.

No changes to the forecast for today or Thu with a continental ridge of high pressure flexing over the area. Difference for this heat spell is the source region is continental in nature.
This will result in potentially higher MaxTs, but also less humid with more of a w'ly sfc component rather a s'ly component.

Heat Advisories have been issued for most of the area today outside of the mountains and southern Shenandoah Valley. These locations will be just shy of criteria given lower Td values. Even with that said, expect heat indices between 96-102 degrees outside of the advisory with 100-105 degree heat indices in the advisory area (i.e the Baltimore/DC metros). Air temps will near record levels (see climate section below) with most seeing highs east of the Alleghenies in the upper 90s and lower 100s. A strong dome of high pressure of central Great Lakes is to thank for the high heat yielding a steady supply of +25 to +28 degree C 850 mb warm air advection into the region.
Similar temps and heat indices are expected on Thu although a few more clouds and an isolated t-storm may be observed since the atmosphere will be less capped. Heat headlines will likely be needed once again for portions of the region Thu.

On top of the heat, will come the concern for haze/poor air quality.
The respective air quality agencies in MD and VA have issued Code Orange Air Quality Alerts for the DC/Baltimore metros. This is largely due in part to dense smoke aloft from wildfires over western Ontario, Canada. Over the next couple of days, the smoke may circulate across the area around the periphery of the upper high over the Midwest. So, expect gradually deteriorating air quality conditions across the local area through Fri.

KEY MESSAGE 2...Thunderstorm chances increase this weekend and could potentially linger into early next week as a front drops into the region.

Temps are expected to run a few degrees cooler but remain hot on Fri with highs in the 90s. Tds are forecast to drop into the 50s behind a weak front that will move through from the NE, leading to lesser instability and decreased chances for afternoon showers and t-storms.

A sw disturbance will descend down in NW'ly flow through the Great Lakes on Sat. Surface winds will turn out of the SW in response to the approaching sw, drawing deeper moisture back nwrd into our FA. Most solutions favor Tds reaching near 70 during the afternoon hours. That coupled with height falls aloft ahead of the sw will lead to increased chances for afternoon showers and t-storms. Some of these storms could potentially be strong to severe with modest flow aloft and a high CAPE/DCAPE environment in place. Forecast confidence decreases by Sun, but t-storms could be possible again if the system's cold front remains upstream, keeping a more unstable airmass in place.

AVIATION /12Z WEDNESDAY THROUGH SUNDAY/
VFR and mostly dry conditions will likely continue through Thu.
Smoke aloft will result in a hazy appearance of the sky through Fri although vsby reductions are not likely at this time. An isolated t-storm is possible Thu afternoon/evening although confidence remains low at this time.

Prevailing VFR conditions are expected Fri into the weekend.
Showers and t-storm will be possible each afternoon/evening with the greatest likelihood this weekend. Winds will remain light out of the W and NW with speeds less than 15 kts.

MARINE
Southerly channeling will likely result in a period of SCA conditions through daybreak across the middle and lower Bay.

Sub-SCA level NW'ly winds are expected Thu and Fri. More widespread t-storm activity and the need for SMWS will be needed over the weekend as a cold front sags south. S'ly channeling also returns to portions of the waters Sat into Sun.

CLIMATE
A period of well above normal temperatures is expected Wednesday and Thursday, with daily record highs likely to be set for some locations on Wednesday, although Thursday looks hotter.

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

LWX WATCHES/WARNINGS/ADVISORIES
DC...Heat Advisory until 8 PM EDT this evening for DCZ001.
MD...Heat Advisory until 8 PM EDT this evening for MDZ003>006-008- 011-013-014-016>018-502>508.
VA...Heat Advisory until 8 PM EDT this evening for VAZ026>031-040- 051-053>057-501-502-505-506-526-527.
WV...Heat Advisory until 8 PM EDT this evening for WVZ050>053-055- 502-504.
MARINE...None.