Marine Weather and Tide Forecast for Annandale, VA

NEAR TERM /THROUGH TONIGHT/
Slightly warmer conditions this afternoon with added sunshine and less wind as high pressure centered over the southeastern U.S builds eastward into the region. 850 mb temperatures look to rise 5 to 8 degrees C compared to where were this time yesterday yielding slightly warmer high temperatures at the surface. Highs today are forecast to push into the upper 30s and low to mid 40s for most with upper 20s and low 30s forecast across the mountains. Wind chill factors should remain fairly similar to actual air temperatures with light west to southwest winds at 5 to 15 mph. Occasional gusts up to 20 mph are possible along the higher ridges and near the waters.

By tonight, south to southwesterly warm air advection ensues as high pressure pushes slowly off the southeast U.S coast. This will hold low temperatures closer to freezing in most locations. Sheltered valleys will likely dip into the mid to upper 20s and low 30s. Winds will help aid in keeping temperatures up especially over the ridges as a strong west to southwest 925 mb low level jet amplifies over the area. This will enhance wind gusts between 40 to 45 mph over the mountains with a few localized ridges pushing close to advisory criteria. Elsewhere, expect 20 to 30 mph gusts as the sun comes up and mixing ensues early Sunday morning. At this time, Wind Advisories are not expected given the small spatial area affected.

SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/
High pressure drifts off the southeast U.S coast Sunday allowing for return southwesterly flow to pump warmer air into the region. Meanwhile, low pressure will pass to the north across southeast Canada leaving a tightened gradient over the region.
With that said, expect a rather breezy and mild Sunday with dry conditions. Highs for most east of the Alleghenies will push into the mid to upper 50s with even a few low 60s across northern and central VA east of the Blue Ridge. Mountain locations and those along the PA/MD line will see highs in the 40s and low 50s. Wind gusts look to range between 20 and 30 mph especially during the late morning and early afternoon hours.
Mountain locations will see gusts up to 40 mph especially during the front half of the day with a strong low level jet passing overhead.

Winds will gradually slacken Sunday evening into Sunday night with increasing clouds as the next low pressure system tracks north and east from the southern Plains and lower MS River Valley. This low pressure system will send a warm front and piece of shortwave energy through the area late Sunday into the first half of Monday providing a renewed round of widespread precipitation across the region. Most of what falls will be in the form of rain although a little mixed precipitation cannot be ruled out in the sheltered/high valleys of the Alleghenies/Catoctins late Sunday night into early Monday morning. 12z guidance has trended somewhat warmer with this threat eliminating any widespread concerns. Overall the resultant front and shortwave look fairly progressive as they track eastward from the mid- MS and Ohio River Valley. This will lead to rainfall amounts of around a 0.10-0.25" areawide with locally heavier amounts up to 0.50" along and west of the Alleghenies. Rain chances will diminish Monday evening into Monday night outside the mountains. This will be a brief reprieve before the next front and wave of low pressure arrive Tuesday into midweek.

High temperatures Monday continue to trend downward given the extra cloud cover and increased rain chances across the region. Most locations along and north of I-66/US-50 will see highs in the mid to upper 40s and low 50s while locations south see highs in the mid to upper 50s. Lows Monday night will fall back into the upper 30s and low to mid 40s.

LONG TERM /TUESDAY THROUGH SATURDAY/
A deep upper level trough will dig across the Mid-Atlantic Tuesday and into Wednesday before becoming negatively tilted as it pivots towards New England. At the surface, the upper level trough will push a low pressure system north of the area in Northern Canada with the associated cold front moving through the forecast area Tuesday night through Wednesday. Models are in good agreement for widespread rain showers Tuesday night and Wednesday. Given recent drought conditions, rainfall is expected to be beneficial. As temperatures drop overnight, rainfall will transition to snow at higher elevations, mainly along and west of the Alleghenies. Winds become gusty in the wake of the frontal passage, with northwest winds gusting 15 to 25 knots (locally higher at high elevations)
Wednesday. Conditions dry out and winds diminish Thursday as surface high pressure builds over the Mid-Atlantic.

The warmest day of the long term period will be in Tuesday with high temperatures in the 50s and 60s. As the cold front pushes through the area Tuesday night and into Wednesday, it creates a large spread in temperatures Tuesday night and Wednesday. Overnight lows will be in the 40s and 50s ahead of the frontal boundary with the Alleghenies dipping into the low 30s in the wake of the frontal boundary. Additionally, high temperatures on Wednesday will be in the 50s to low 60s east of the Blue Ridge with those further west topping out in the 30s to low 40s.

In the wake of the frontal boundary, overnight low temperatures on Wednesday dip into the teens and 20 with only the metro areas staying in the 30s. High temperatures on Thursday and Friday will be in the 30s and 40s with overnight lows in the teens and 20s each night.



AVIATION /19Z SATURDAY THROUGH THURSDAY/
VFR conditions are expected at all terminals through Sunday as high pressure passes to the south of the region. Outside of a few passing mid and high level clouds, wind and LLWS appear to be the only concern for aviators this weekend. Southwest winds look to gusts between 15 to 20 kts this afternoon with gusts up to 25 kts Sunday.
This is due largely in part to a strengthening 925 mb LLJ later this evening and into tonight which will promote LLWS (260-280 degrees at 35 to 40 kts around 2-2.5 kft) amongst the terminals. Any LLWS will likely diminish mid to late SUnday morning as the LLJ weakens.

Winds will continue to decrease Sunday as a warm front and wave of low pressure push across the region. This will lead to the next chance of MVFR and IFR conditions as widespread rain overspreads the terminals. WInds will turn to the south and southeast with gusts less than 15 kts. The rain will diminish Monday evening and night although sub VFR ceilings and vsbys could linger given the warm/moist airmass over the colder surface below.

Flight restrictions as possible Tuesday as precipitation chances increase at all terminals. Sub-VFR conditions are likely Tuesday night and into Wednesday as widespread rain showers bring reduced visibilities, low ceilings, and potential LLWS to all terminals. In the wake of a frontal passage, light and variable winds shift to northwesterly, gusting up to 30 knots Wednesday. VFR conditions return Thursday through the start of the weekend as high pressure builds back into the region. Winds will remain elevated Thursday on post west to northwest flow.

MARINE

Sub-SCA level winds with gusts up to 15 kts are possible for the remainder of the afternoon across the waters. This will be a brief lull with winds likely to increase later this evening and into the overnight hours as a low level jet amplifies over the region. Small Craft Advisories are in place for most of the waters outside of the northern bay/tidal Potomac outside this evening through early Sunday afternoon. Sub-SCA level conditions are expected to return to the waters Sunday evening into Monday morning. This will be brief though with winds likely increasing again Monday over the open waters of the Chesapeake Bay and tidal Potomac due to southerly channeling.

SCA criteria winds are likely beginning Tuesday evening and continuing through Wednesday in the wake of a frontal passage.
Northwesterly winds gust up to 25 knots Wednesday afternoon.

FIRE WEATHER

A Fire Danger Statement has been issued Sunday for portions of northern and central Virginia in coordination with the State of Virginia Department of Forestry.

Despite the colder temperatures, a number of wildfires have recently broken out in dry/gusty post-frontal environments. Tis is due largely in part to the drier airmasses behind the fronts combined with antecedent drought conditions and gusty winds.

For late tonight through most of Sunday, a tight pressure gradient brings gusty winds to the area, primarily at higher elevations.
Southwesterly winds gust 20 to 25 mph across the area, with gusts around 30 to 40 mph expected at higher elevations. Relative humidity values will drop into the 25 to 35 percent range across portions of northern and central VA with 30-45 percent values elsewhere east of the Alleghenies. These values will gradually recover late SUnday afternoon and evening as moisture advection increases on south to southwesterly flow.

A wetting rain comes in Monday across a vast majority of the region.
Rainfall amounts of a tenth to a quarter of an inch can be expected with locally heavier amounts west of the Alleghenies and along the crest of the Blue Ridge.



TIDES/COASTAL FLOODING
Tidal departures of around 1 ft below normal are expected today.
Departures will continue to recover tonight as winds diminish. Tidal departures recover to near normal by Sunday as winds shift to a more southerly direction. COntinued recovery expected under south to southeast flow Monday and Tuesday next week.

LWX WATCHES/WARNINGS/ADVISORIES
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 7 PM this evening to noon EST Sunday for ANZ531>534-537>543.