|Dew Point:||37.0°F (2.8°C)|
|Sea Level Pressure:||29.92" (1013.1 mb)|
Lo 39 °F
Lo 45 °F
Lo 47 °F
Lo 41 °F
Lo 37 °F
A chance of rain, mainly after 5am. Cloudy, with a low around 39. Southeast wind around 6 mph. Chance of precipitation is 30%.
Rain before 3pm, then patchy drizzle with a slight chance of rain between 3pm and 4pm, then patchy drizzle after 4pm. High near 50. Southwest wind 8 to 10 mph. Chance of precipitation is 100%. New precipitation amounts between a tenth and quarter of an inch possible.
Patchy drizzle. Patchy fog after 8pm. Otherwise, mostly cloudy, with a low around 45. Southwest wind around 6 mph.
Patchy drizzle and fog before 1pm, then a slight chance of rain after 1pm. Cloudy, with a high near 56. Southwest wind 5 to 7 mph. Chance of precipitation is 20%.
Rain likely, mainly after 1am. Cloudy, with a low around 47. South wind 3 to 6 mph. Chance of precipitation is 60%.
Rain. High near 52. Chance of precipitation is 90%.
Rain likely. Cloudy, with a low around 41. Chance of precipitation is 60%.
Rain. High near 46. Chance of precipitation is 90%.
A chance of rain. Mostly cloudy, with a low around 37. Chance of precipitation is 40%.
Thu Jan 19 2017
SYNOPSIS... High pressure will move off to the east tonight. A warm front will move into the area Friday and stall out nearby through Saturday. Low pressure will affect the area Sunday and Monday. Weak high pressure may approach the area Tuesday before a cold front approaches Wednesday.
NEAR TERM /THROUGH FRIDAY/... High pressure is currently located along the eastern seaboard. With thin spots in the cirrus, some locations have already fallen to their dewpoints (lower to mid 30s), necessitating lowering the low temperatures in some locations. However, with thicker clouds arriving from the southwest, the temperatures should hold steady or rise a few degrees the second half of the night. Any rainfall arriving in the southwest corner of the CWA late tonight will be very light.
Warm advection, albeit rather weak, starts late tonight and continues on Friday as the closed low opens into a shortwave and lifts northeast across the region. With this overall being a weakening feature, rainfall is not expected to be particularly significant on Monday, generally less than a quarter of an inch. Rain may move through as several bands as suggested by short-range high resolution guidance, so went with "periods of rain" given potential for dry intervals. It`s possible the first band is little more than sprinkles, with the second band providing most of the measurable rainfall. The gap between any such bands remains uncertain. That all having been said, in general we expect rain to arrive across metro DC 8-10 AM, with light rain likely occurring at swearing in, and the rain should mostly depart 2-4 PM. However, the low clouds, fog and drizzle may persist given light southeast flow and no frontal passage expected. With the rain expected on Friday, expect highs to stay below guidance, mid to upper 40s generally.
SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... Friday night into Saturday night, the region is more or less between systems, but with the warm front stalling to our south and nothing to disturb the air mass, low clouds, mist, drizzle and perhaps fog look likely to remain over the region, at least through early Saturday. Some insolation may reach the ground enough to dissipate the drizzle, mist and fog on Saturday afternoon, but it will be short lived. Warm advection precip with the next complex low pressure system will start Saturday evening, with rain likely to overspread much of the region late Saturday night.
With the clouds, mist, drizzle and patchy fog, lows on Friday night should not drop much, with readings generally in the 40s. Highs on Saturday will be dependent on the clouds thinning a bit with a break in the fog and drizzle. Assuming this occurs, we will likely rise into the low-mid 50s. Saturday night lows should stay in the 40s with the clouds and rain arriving late.
LONG TERM /SUNDAY THROUGH THURSDAY/... A storm system will develop over the Mississippi Valley and deepen as it moves toward the east-northeast Sunday and Sunday night. This low will send energy into our region Sunday into Sunday night, bringing rain to the region.
On Monday, the main low will move to the northeast a little further. The threat for rain continue Monday into early Monday evening. Temperatures will remain mild for January but cooler air quickly lines up on the doorstep of the region to move in Monday night. Some guidance suggests enough cold air may arrive before precipitation ends to allow a change to snow, particularly across higher elevations well northwest of I-95 corridor. Will need to watch this potential. Other concern Monday is for gusty winds, and some guidance is hinting at wind advisory gusts as the low passes just to the east. Will need to look at this harder in coming day or two.
High pressure will usher in drier air Tuesday and Tuesday night. Clouds will break for sun, except for clouds and upslope rain and/or snow showers in the Potomac Highlands possible.
An upper level trough of low pressure will sag from the Great Lakes region toward the mid-Atlantic Wednesday. A return of mild air from the south will evolve ahead of the trough with some sunshine giving way to some clouds.
Temperatures will be seasonable with some sunshine Thursday. An upper level trough of low pressure will be just to the north but dry conditions should prevail. There is a chance of upslope rain or snow showers in the Potomac Highlands.