textproduct: Baltimore/Washington

WHAT HAS CHANGED

No major changes have been made to the previous forecast.

KEY MESSAGES

- 1) Slightly cooler and drier conditions are forecast for today, before showers and thunderstorms return Sunday.

- 2) Daily chances for showers persist into next week along with cooler temperatures.

DISCUSSION

KEY MESSAGE 1...Slightly cooler and drier conditions are forecast for today, before showers and thunderstorms return Sunday.

High pressure currently centered across southern Quebec will continue to build southeastward over the course of the day today, eventually reaching the Gulf of Maine by this evening. As the high shifts further east, winds will gradually shift from out of the north/northeast this morning to out of the east and then southeast this afternoon. Persistent cool/dry advection has enabled dewpoints to drop into the upper 50s to mid 60s as of early this morning. With this somewhat drier airmass in place, zonal flow aloft, and the influence of the high building to our north, conditions are expected to remain dry through the day today. Temperatures are forecast to climb into the 70s to near 80 beneath mostly cloudy skies.

High pressure will shift further offshore tomorrow while a shortwave disturbance tracks eastward across southern Ontario and Quebec. Winds at the surface will turn southerly in response to the high moving further offshore, while winds aloft turn westerly in response to the shortwave passing to our north. The net effect of these wind shifts will be to draw a warmer, more humid airmass back into the area from the south and west. Temperatures are forecast to climb well into the 80s with dewpoints jumping back into the lower 70s. Model guidance suggests that chances for showers and potentially a few thunderstorms will increase tomorrow afternoon into tomorrow night as a cold front approaches from the north, moving into the warm and humid airmass. This cold front will eventually move through the area Sunday night, causing winds to shift to out of the north to northeast.

KEY MESSAGE 2...Daily chances for showers persist into next week along with cooler temperatures.

Upper-level ridging breaks down early next week, with multiple shortwave disturbances moving across the Mid-Atlantic in the days following. Mid-level moisture brought in from the south will overrun moist northeasterly flow off the Atlantic, leading to daily chances for showers. Temperatures remain somewhat uncertain due to model discrepancy in cloud cover, but they continue to favor the cooler side of guidance given a possible cold air damming surface pattern.

Well below average temperatures could last through midweek as nearby disturbances continue to bring rain and showers to the area. Towards the bay and coastlines, wind gusts could remain elevated through late next week as these disturbances shift offshore. Overall, coastal flooding could become something to watch out for next week. See the coastal flooding section below for more details.

AVIATION /06Z SATURDAY THROUGH WEDNESDAY/

VFR conditions are expected through the day today as winds gradually shift from the northeast to the southeast. MVFR ceilings may be possible later tonight, with gradual improvement back to VFR tomorrow morning. Winds will be out of the south tomorrow, and a few showers and thunderstorms may be possible tomorrow afternoon into tomorrow night as a cold front approaches from the north. Winds eventually shift to out of the north later Sunday night as the front moves through. Sub-VFR ceilings appear likely behind the front in northeasterly flow on Monday.

Sub-VFR ceilings likely continue on Tuesday and Wednesday, along with showers and gusty northeasterly winds.

MARINE

Small Craft Advisory conditions continue over the main stem of the Bay within northeasterly flow early this morning. Winds are expected to decrease after sunrise and then gradually shift around to out of the east. Winds pick up out of the east to southeast tonight, with SCA conditions possible. Low-end SCA level winds may linger into Sunday within southerly flow across the wider waters of the Bay. A cold front will move over the waters Sunday night, causing winds to shift to out of the north. SCA conditions may be possible in the surge of northerly winds behind the front Sunday night. SCA conditions will likely continue within northeasterly flow on Monday, and then easterly flow Monday night.

Heading into the middle of next week, winds could approach Gale conditions between Tuesday and Wednesday within northeasterly flow as a strong area of high pressure builds to our north.

TIDES/COASTAL FLOODING

Tidal anomalies will gradually increase as winds shift from the northeast this morning to east this afternoon, southeast tonight, and then south tomorrow. Annapolis could come close to Minor Flooding tomorrow, but for now the forecast has them just below in Action stage. After a brief drop in anomalies behind a cold front Sunday night, anomalies should gradually increase once again next week within onshore flow. At least Minor flooding appears likely during the middle of next week, and Moderate flooding can't be completely ruled out.

LWX WATCHES/WARNINGS/ADVISORIES

DC...None. MD...Small Craft Advisory until 10 AM EDT this morning for MDZ008. VA...None. WV...None. MARINE...Small Craft Advisory until 10 AM EDT this morning for ANZ530>533-539>541. Small Craft Advisory until 10 AM EDT this morning for ANZ534- 537-543. Small Craft Advisory from 5 PM this afternoon to 1 AM EDT Sunday for ANZ534-537-543.