Chesapeake Bay From Sandy Point to North Beach MD Marine Forecast
|Rest Of Tonight...E Winds 5 To 10 Kt. Waves 1 Ft. Rain. Vsby 1 To 3 Nm.|
|Thu...E Winds 10 To 15 Kt With Gusts To 20 Kt. Waves 1 To 2 Ft. Rain. Vsby 1 To 3 Nm.|
|Thu Night...Nw Winds 10 To 15 Kt With Gusts To 25 Kt. Waves 2 Ft. Rain Likely.|
|Fri...W Winds 15 To 20 Kt With Gusts To 30 Kt. Waves 3 Ft. Scattered Showers.|
|Fri Night...Nw Winds 15 To 20 Kt With Gusts To 30 Kt. Waves 3 Ft.|
|Sat...Nw Winds 15 To 20 Kt With Gusts To 30 Kt. Waves 3 Ft.|
|Sat Night...Nw Winds 10 To 15 Kt With Gusts To 25 Kt. Waves 2 To 3 Ft.|
|Sun...Sw Winds 5 To 10 Kt. Waves 1 Ft.|
|Mon...N Winds 5 To 10 Kt. Waves 1 To 2 Ft. A Chance Of Showers Through The Day, Then A Chance Of Rain Through The Night.|
|Area Forecast Discussion|
National Weather Service Baltimore MD/Washington DC
856pm EDT Wednesday Mar 20 2019
Synopsis: Coastal low pressure will develop over North Carolina tonight and the low will pass through our area Thursday. The low will intensify as it moves off to the northeast Thursday night through Friday and high pressure will return for the weekend. Low pressure may impact the area early next week with more unsettled conditions possible.
Near Term - Until 6am Thursday Morning
Clouds continue to gradually lower and thicken tonight ahead of low pressure developing over the eastern Carolinas. Intermittent light rain already encroaching on southern Maryland as of early this evening, and rain is expected to expand quickly northward while increasing in intensity after midnight (mainly east of Interstate 81). Some moderately heavy rain is likely by daybreak between the Blue Ridge and Interstate 95
.SHORT TERM /6am THURSDAY MORNING THROUGH FRIDAY NIGHT/... There is a decent chance this system will be an "overperformer" when it comes to precipitation amounts. Strong height falls with an approaching negatively-tilled mid/upper trough, attendant mid and upper jet/PVA, and strong low-level moisture flux all point to an area of moderately heavy rain from Thursday morning the mid Thursday afternoon across northern Virginia and central Maryland (mainly between the Blue Ridge and I-95). In addition, mid-level lapse rates of around 7 C/km will contribute to embedded convective elements/heavier rainfall rates (possibly 1/2 inch per hour). A few rumbles of thunder are possible as well given all the strong forcing in place, despite low CAPE values (less than 200 J/kg).
The low pressure system will be intensifying NE of our area Thursday night and the shortwave will phase with additional northern stream energy on Friday. This will cause some showers to develop on Friday afternoon. In the meantime, high pressure will be building west of our region over the central CONUS. The gradient from this and the low pressure suggests that gusty NW winds will develop over our area Friday into Friday night. Gusts between 30 and 40 mph are possible across most of our CWA, and gusts up to 50 mph are possible over higher elevations/west of the Blue Ridge. Snow showers west of the Allegheny Front are possible during this time as well, with dry conditions expected elsewhere
Long Term - Saturday Through Wednesday
High pressure will gradually build over the region through the day Saturday as shortwave ridging aloft moves into the Ohio Valley. Enough of a pressure gradient will exist between the building area of high pressure and the departing low over the northeast to maintain some gusty winds through the day. However, winds are gradually expected to diminish late Saturday as the low moves further away and the gradient relaxes. The high will move overhead Saturday Night, then slide offshore on Sunday. This will allow a southerly return flow to develop, enabling warmer conditions to work their way back in. High temperatures will run about ten degrees warmer on Sunday with highs in the low 60s (compared to the low 50s on Saturday).
On Monday, disturbances in both the northern and southern streams will start to approach the area. Model guidance differs substantially with respect to the handling of these disturbances, casting rather high uncertainty on our sensible weather forecast for the Monday through Tuesday time frame. In terms of deterministic solutions, the 12z GFS has a strong northern stream disturbance and a more diffuse, weak southern stream disturbance. At the surface, this solution results in a strong area of high pressure developing over the Upper Midwest, and a strong, progressive cold front being driven southward across the area late Monday through Monday Night. This would result in a period of precipitation late Monday afternoon through Monday Night that would clear the area by Tuesday morning. The 00z Euro, on the other hand, showed a slightly weaker, further northward displaced northern stream disturbance, and a stronger southern stream disturbance (compared to the GFS solution). This combination results in the baroclinic zone stalling out overhead and a more prolonged period of precipitation Monday through Tuesday. The general notion of a low predictability forecast is supported by the 00z EPS members, which show more than 30 degrees of spread in the temperature field through much of the Monday Night through Wednesday time period.
To summarize, the general synoptic pattern appears favorable for us to see some precipitation at some point during the late Monday through Tuesday timeframe. However, most of the finer scale details, including the timing, duration, and character of the precipitation remain in question. There's plenty of cold air associated with the northern stream disturbance, so some wintry precipitation isn't entirely out of the equation, even at lower elevations. However, given the level of uncertainty it's far too early to speculate with respect to what will happen with precipitation type.
A coastal low pressure system will move over the waters on Thursday bringing rainfall and increasingly gusty easterly winds. This low pressure system will intensify Thursday night into Friday as it moves NE and away from us. Breezy conditions are expected over the waters on Friday into Friday night and additional Small Craft Advisories or Gale Warnings may be needed during this time.
Small Craft Advisory level winds appear likely during the day Saturday. Winds will weaken Saturday Night as high pressure builds in Saturday Night
Strong mid/upper height falls/PVA/jet divergence and low-level moisture flux as well as elevated instability will contribute to a widespread soaking moderately heavy rain, generally between the Blue Ridge and I-95. Amounts of 1.5-2+ inches are likely here, with isolated totals of 3 inches possible. Should these higher totals be realized, especially within a 6-9 hour window, minor flooding issues of small creeks, streams and urban areas may result. The heaviest and steadiest rain looks to be between 6am and 3pm Thursday. Most recently, the 21Z SREF (which had previously had many members with lower Quantitative Precipitation Forecast shifted further east) has trended wetter, in line with the GFS/NAM/ECMWF. Therefore, had the confidence to hoist a Flood Watch for the DC/Baltimore metro areas for Thursday through Thursday evening. The steadiest rainfall is expected Thursday morning through mid Thursday afternoon, but residual runoff issues may persist into the evening hours Thursday
Tides / Coastal Flooding
Increasing onshore flow ahead of a developing coastal low pressure system will cause tidal anomalies to continue to increase, with minor flooding likely Thursday afternoon and Thursday evening
NOAA Baltimore MD/Washington DC Office: Watches - Warnings - Advisories
DC...Flood Watch from 6am EDT Thursday through Thursday evening for DCZ001. MD...Flood Watch from 6am EDT Thursday through Thursday evening for MDZ004>006-011-013-014-503>508. VA...Flood Watch from 6am EDT Thursday through Thursday evening for VAZ052>054-505-506. WV...None.
Small Craft Advisory from noon Thursday to 6am EDT Friday for ANZ532-533-540>542.
Small Craft Advisory from 6pm Thursday to 6am EDT Friday for ANZ530-531-535-536-538-539.
Small Craft Advisory from 6am Thursday to 6am EDT Friday for ANZ534-537-543.