Marine Weather and Tide Forecast for Alexandria, VA

KEY MESSAGES
- Increasing confidence for widespread soaking rainfall and limited snow (i.e the mountains) with an area of low pressure set to impact the area Sunday into Sunday night.

- The big thaw continues! Above normal temperatures are expected throughout next week.

DISCUSSION

KEY MESSAGE 1...Increasing confidence for widespread soaking rainfall and limited snow (i.e the mountains) with an area of low pressure set to impact the area Sunday into Sunday night.

KEY MESSAGE 1 DESCRIPTION...

Finally, some better agreement amongst the models with some of the hi-res guidance now catching the front end of the low pressure system set to impact the area Sunday into Sunday night. Even with that said, some subtle differences remain in regards to timing with some of the guidance trending slower (i.e precip starting late Sunday afternoon continuing through pre-dawn Monday morning)
while other model runs are faster. The intensity of the system also remains uncertain while the track is becoming a bit better aligned.

The waffling of both the deterministic/ensemble model suites continues to show a more progressive system with unphased flow (limited interaction between the northern/southern jetstream). Most solutions have an area of low pressure ejecting out of the Mid-South toward the central/southern Appalachians Sunday morning/afternoon and off the VA/NC coast Sunday night into Monday morning. Meanwhile, high pressure will remain up across eastern Quebec leaving a marginal cold air along and north of I-70 and west of Blue Ridge.
This puts the highest probabilities for wintry weather along the climo favored areas west of US-15 toward the higher elevations of the Alleghenies, Catoctins, crest of the Blue Ridge, and hilltops of the Potomac Highlands.

The bulk of the area will likely see soaking/beneficial rainfall.
Latest 6/12z solutions continue to hint at a southern suppression while the EURO/EC are slightly north. With that said, the heaviest slug of precipitation may, in fact, be confined to areas south of I- 66/US-50 with lighter amounts to the north.
Guidance continues to show the probabilities of 1" of rain roughly between 10 to 30 percent across the area with the higher end of these probs along and south of US-33/I-64. Flooding could become an issue if higher rainfall values are realized, especially in areas with residual snow pack and icy rivers/creeks (not to mention the cold/less absorptive ground).
Any flooding will likely be due to excessive runoff with average QPF right now ranging from 0.25-0.50 north of I-66/US-50 to 0.50-1" to the south. These values are dependent on where low pressure tracks with a subtle shift north/south playing a big difference. Low pressure will exit Monday morning into Monday afternoon.

High temperatures Sunday will range from the mid 30s to low 40s across the area with overnight lows at or just above freezing. Highs Monday will warm back into the upper 30s and mid 40s as the system pulls away. Keep checking the discussion in the coming days to see how things evolve with this forecast.

KEY MESSAGE 2...The big thaw continues! Above normal temperatures are expected throughout next week.

KEY MESSAGE 2 DESCRIPTION...

Behind the late weekend storm system, high pressure returns to the area and sticks around through the middle of next week. This will result in temperatures rising well above normal. Some areas could reach the 60s by Wednesday and Thursday. Low pressure passing through the Great Lakes could bring a chance of rain Wednesday into Wednesday night.

AVIATION /19Z THURSDAY THROUGH TUESDAY/

NW winds will continue to gust up to 25 kt through early evening, then diminish. BKN-OVC040-050 cigs will also persist through this evening, then begin to clear after midnight.

Sub-VFR conditions look to return to the area Sunday as an area of low pressure passes south of the region. This storm system will bring increased cloud cover and precipitation chances to the region.
Rain and some wintry precipitation is possible mainly north and west of the corridor terminals Sunday into Monday morning. Confidence remains low for substantial wintry precipitation with 15 to 25 percent probs focused toward HGR/MRB compared to IAD. Most will see soaking rainfall with localized runoff on impervious surfaces. Once again, this is subject to change based upon the availability of cold air and track of low pressure. The storm system pulls out of the area Monday with conditions briefly improving Tuesday before another system arrives by the middle of next week.

MARINE

Brisk NW winds will continue overnight, mainly in the central and southern portions of the Chesapeake Bay.The Small Craft Advisory has been extended overnight in these areas. Winds diminish on Friday and are expected to stay below SCA criteria through Saturday. Northwest winds on Friday become light and variable overnight and then shift to southerly on Saturday.

Additional Small Craft Advisories will be needed Sunday night into Monday as low pressure passes to the south. Winds will turn east and northeast Sunday into Monday.

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...Small Craft Advisory until 6 PM EST this evening for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 PM EST this evening for ANZ530- 535-536-538-542.
Small Craft Advisory until midnight EST tonight for ANZ531-532- 539-540.
Small Craft Advisory until noon EST Friday for ANZ533-534-537- 541-543.