arlwx

Seeing a few mixed-in s***flakes falling past my Arlington streetlight.

The latest from LWX: (snip) .NEAR TERM /THROUGH TONIGHT/... A early stationary boundary remains across the Tennessee Valley and southern Virginia early this morning. With ample lifting mechanisms, a band of snow has developed, mainly Winchester- Washington DC and points north. Its been a bit too warm for much to stick yet, but with wet bulb cooling, anticipate that will come soon. The p-type forecast remains tricky today. While much of the ongoing precip is snow, low level temperatures are mostly above freezing, and temperatures aloft will be warming. Thus, we`re looking for a change over to sleet, and then rain...with freezing rain where low level cold air remains trapped. Latest HREF runs generally match current forecast evolution, and thus have not changed much in that regard. The only concern is whether there is too much emphasis on freezing rain in Central Virginia based on current temperatures. By noon, most locations will be seeing just rain, with perhaps northern Maryland and the northern Shenandoah Valleys as the exceptions. Further, most guidance sources suggest there will be a bit of a lull in precipitation between shortwave impulses. For that reason, will not be extending Advisories beyond 1pm at this time. In summary...a Winter Weather Advisory is in effect for immediate metro Baltimore, the farther northern and western suburbs of Washington/Baltimore and for locations near/west of the Blue Ridge and Catoctin Mountains. A Winter Storm Warning is in effect for western Allegheny and western Mineral Counties where several inches of snow are expected before changing to ice from freezing rain. A stronger disturbance will approach this evening, causing steadier precipitation to break out once again. During this time, most areas will be rain, but freezing rain is expected across western MD and western Mineral County in WV. Freezing rain may also hang on for the higher elevations near the Mason- Dixon Line into the Potomac Highlands. Winter headlines may have to be adjusted near the Mason-Dixon Line into the Allegheny and Potomac Highlands due to the possibility of freezing rain. Confidence is too still low to do so at this time. (snip)

From the latest LWX discussion: .SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... An area of low pressure will be getting organized over the middle Mississippi River valley this evening into the overnight. Precipitation associated with the warm front attached to this system will spread into western portions of the CWA late tonight. Precipitation should start as mostly, or all, snow for a brief period tonight into early Monday morning, particularly over eastern WV and western MD. However, warm air aloft will quickly change precipitation over to a wintry mix Monday morning, and most areas change over to rain by the afternoon. The best shot to see any accumulating snowfall will be well to the north and west of I-95, particularly across eastern WV and western MD. Amounts of 1-2 inches are possible as you get north and west of the I-95 corridor, with amounts of 2-4 inches possible across eastern WV and western MD (with some isolated higher amounts possible). That being said, could still be seeing a mix of wintry precip Monday morning during the morning rush. Not expecting any big impacts across the DC/Baltimore metro areas at this time. Without a cold surface high to the north to keep the cold air locked in place, any mixed precipitation is likely to be brief and light, with only trace or light amounts of ice expected. The one exception may be near the Mason-Dixon Line and across the Allegheny and Potomac Highlands. A layer of cold air may be tough to scour out due to light winds underneath the subsidence inversion. Did allow for some more freezing rain across these areas. Rain/showers will continue off and on through Tue until frontal passage late Tue. Given the expected wintry mix and potential for hazardous travel conditions Monday morning, winter weather advisories are likely to be required for NW parts of the fcst area. (snip)

Forecast update from LWX: (snip) NEAR TERM /THROUGH SATURDAY/... Radar imagery shows leading edge of rain pushing northeastward through central portions of Bath, Rockbridge, and Amherst Counties in southwestern Virginia. We have slowed down this forward progress of rainfall by an hour or two. This leading edge should enter our CWA counties of Highland, Augusta, and Nelson Counties around 430am. Temperatures in this region of 28 to 32 degrees would support freezing rain for a few hours after onset. As this rain moves farther northeast just before and during daybreak today, temperatures across the metro areas, eastern and northeast Virginia, and parts of central Maryland will rise a few degrees to just above freezing. Thus, the expectation of freezing rain is these areas are minimal to none through this morning. Areas of greater concern for freezing rain and ice accumulations are along and west of US 15 from Frederick County, Maryland, southwest into western Loudoun and northern Fauquier Counties in Virginia, and all other areas to the southwest and west. A Winter Weather Advisory remains in effect for the aforementioned areas through midday or into this afternoon. Parts of western Maryland and northern West Virginia could see an ongoing threat for ice accumulations through late this afternoon. Elevations below 1500 feet would be more susceptible. As temperatures modify throughout the day today into tonight, there will be a transition to plain rain with rain amounts averaging one half to one inch. The low pressure system responsible for this wintry weather and soaking rainfall will depart to the northeast later tonight and Saturday morning. Rainfall will end from south to north during this period. High pressure will build into the region Saturday. A shift of wind direction to more of a west-northwest flow will promote some upslope snowfall later Saturday into Saturday night. A couple of inches of snow could occur at elevations above 2500 feet. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... Upslope snow will continue Saturday night before tapering and ending Sunday. Cold high pressure will become the flavor Sunday into Sunday night. Temperatures will be below average. A developing warm front to our southwest will propagate northward later Sunday night. This warm front could bring a wave of light snow or perhaps a mix of snow, sleet or rain to our western and west-central zones. (snip)

National Weather Service Baltimore MD/Washington DC 506 AM EST Thu Dec 12 2019 ANZ530>543-DCZ001-MDZ011-013-014-016>018-508-VAZ052>057-131015- Chesapeake Bay north of Pooles Island MD- Chesapeake Bay from Pooles Island to Sandy Point MD- Chesapeake Bay from Sandy Point to North Beach MD- Chesapeake Bay from North Beach to Drum Point MD- Chesapeake Bay from Drum Point MD to Smith Point VA- Tidal Potomac from Key Bridge to Indian Head MD- Tidal Potomac from Indian Head to Cobb Island MD- Tidal Potomac from Cobb Island MD to Smith Point VA- Patapsco River including Baltimore Harbor- Chester River to Queenstown MD-Eastern Bay- Choptank River to Cambridge MD and the Little Choptank River- Patuxent River to Broomes Island MD- Tangier Sound and the inland waters surrounding Bloodsworth Island-District of Columbia-Southern Baltimore-Prince Georges- Anne Arundel-Charles-St. Marys-Calvert-Southeast Harford- Prince William/Manassas/Manassas Park-Fairfax- Arlington/Falls Church/Alexandria-Stafford-Spotsylvania- King George- 506 AM EST Thu Dec 12 2019 This Hazardous Weather Outlook is for the Maryland portion of the Chesapeake Bay, Tidal Potomac River, and adjacent counties in central Maryland and northern Virginia as well as the District of Columbia. .DAY ONE...Today and Tonight Freezing rain may develop in portions of eastern Virginia very late tonight. Winter Weather Advisories may be required. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Freezing rain is possible in portions of eastern Virginia early Friday. Winter Weather Advisories may be required. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. $$ Hazardous Weather Outlook National Weather Service Baltimore MD/Washington DC 506 AM EST Thu Dec 12 2019 MDZ003>006-501>507-VAZ025>031-036>040-050-051-501>508-WVZ050>053- 055-501>506-131015- Washington-Frederick MD-Carroll-Northern Baltimore- Extreme Western Allegany-Central and Eastern Allegany- Northwest Montgomery-Central and Southeast Montgomery- Northwest Howard-Central and Southeast Howard-Northwest Harford- Augusta-Rockingham-Shenandoah-Frederick VA-Page-Warren-Clarke- Nelson-Albemarle-Greene-Madison-Rappahannock-Orange-Culpeper- Northern Fauquier-Southern Fauquier-Western Highland- Eastern Highland-Western Loudoun-Eastern Loudoun- Northern Virginia Blue Ridge-Central Virginia Blue Ridge- Hampshire-Morgan-Berkeley-Jefferson-Hardy-Western Grant- Eastern Grant-Western Mineral-Eastern Mineral-Western Pendleton- Eastern Pendleton- 506 AM EST Thu Dec 12 2019 This Hazardous Weather Outlook is for eastern West Virginia, northern and central Virginia, and central and western Maryland with the exception of Garrett County. .DAY ONE...Today and Tonight Freezing rain may develop in portions of Virginia very late tonight. Winter Weather Advisories may be required. .DAYS TWO THROUGH SEVEN...Friday through Wednesday Freezing rain is possible in portions of Virginia, West Virginia and Maryland on Friday, mainly in the morning. Winter Weather Advisories may be required. There is a slight winter storm threat Monday and Monday night for areas west of Interstate 95. If the threat materializes, it may cause travel disruptions. .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected at this time. $$

From LWX: Special Weather Statement National Weather Service Baltimore MD/Washington DC 437 AM EST Thu Dec 12 2019 MDZ004-005-503>506-VAZ052-053-055-056-501-502-505-506-121545- Frederick MD-Carroll-Northwest Montgomery- Central and Southeast Montgomery-Northwest Howard- Central and Southeast Howard- Prince William/Manassas/Manassas Park-Fairfax-Stafford- Spotsylvania-Northern Fauquier-Southern Fauquier-Western Loudoun- Eastern Loudoun- Including the cities of Frederick, Ballenger Creek, Eldersburg, Westminster, Germantown, Damascus, Bethesda, Rockville, Gaithersburg, Silver Spring, Lisbon, Columbia, Ellicott City, Dale City, Manassas, Woodbridge, Lake Ridge, Montclair, Reston, Herndon, Annandale, Centreville, Chantilly, McLean, Franconia, Falmouth, Fredericksburg, Warrenton, Turnbull, Purcellville, Leesburg, Ashburn, and Sterling 437 AM EST Thu Dec 12 2019 ...POTENTIAL WINTER COMMUTING HAZARD FOR THE BALTIMORE / WASHINGTON METRO AREAS FRIDAY MORNING... There is a potential for hazardous commuting conditions for the Friday morning commute. A period of freezing rain is POSSIBLE (a 30 percent chance in Carroll County increasing to 50 percent in Fauquier and Spotsylvania Counties) Friday morning across the northern and western portions of the Baltimore / Washington metro areas, which would result in an icy accumulation on area roads. If this threat does materialize during the Friday morning rush- hour, many roads could quickly turn icy. This could lead to dangerous traveling conditions, multiple accidents, and extensive delays. If commuting Friday morning, be aware of the POSSIBILITY of significant travel disruptions. Plan ahead by allowing for extra travel time, and consider using public transportation and telework options. Stay tuned for updates on this potential winter weather episode.

Cartopped in Arlington VA.

Ice storm warnings for far north and west, WWAs for icing for not so far north and west. URGENT - WINTER WEATHER MESSAGE National Weather Service State College PA 354 AM EST Sat Nov 30 2019 PAZ024-025-033-034-302200- /O.UPG.KCTP.WS.A.0005.191201T0000Z-191202T0000Z/ /O.NEW.KCTP.IS.W.0001.191201T0000Z-191202T0000Z/ Cambria-Blair-Somerset-Bedford- Including the cities of Johnstown, Altoona, Somerset, and Bedford 354 AM EST Sat Nov 30 2019 ...ICE STORM WARNING IN EFFECT FROM 7 PM THIS EVENING TO 7 PM EST SUNDAY... * WHAT...Significant icing expected from freezing rain. Total snow accumulations of less than one inch and ice accumulations of one quarter to one half of an inch. * WHERE...Cambria, Blair, Somerset and Bedford Counties. * WHEN...From 7 PM this evening to 7 PM EST Sunday. * IMPACTS...Power outages and tree damage are likely due to the ice. Travel could be nearly impossible, especially late tonight and Sunday morning. PRECAUTIONARY/PREPAREDNESS ACTIONS... The Pennsylvania Department of Transportation and Pennsylvania Turnpike Commission strongly encourage motorists to heed all travel restrictions and delay unnecessary travel as severe winter weather conditions will make travel very hazardous. If you must travel, keep an extra flashlight, food and water in your vehicle in case of an emergency. Call 5 1 1 or visit www.511pa.com for the latest travel, roadway and traffic conditions. To report snow or ice, post to the NWS State College Facebook page, use Twitter @NWSStateCollege, or visit weather.gov/ctp. && $$ URGENT - WINTER WEATHER MESSAGE National Weather Service Pittsburgh PA 350 AM EST Sat Nov 30 2019 MDZ001-301700- /O.UPG.KPBZ.WS.A.0006.191201T0000Z-191201T1700Z/ /O.NEW.KPBZ.IS.W.0001.191201T0000Z-191201T1700Z/ Garrett- Including the cities of Mountain Lake Park, Oakland MD, and Grantsville 350 AM EST Sat Nov 30 2019 ...ICE STORM WARNING IN EFFECT FROM 7 PM THIS EVENING TO NOON EST SUNDAY... * WHAT...Significant icing expected. Total ice accumulations of one quarter to one third of an inch. * WHERE...Garrett County. * WHEN...From 7 PM this evening to noon EST Sunday. * IMPACTS...Power outages and tree damage are likely due to the ice. Travel could be nearly impossible. PRECAUTIONARY/PREPAREDNESS ACTIONS... Travel is strongly discouraged. If you must travel, keep an extra flashlight, food and water in your vehicle in case of an emergency. Prepare for possible power outages. Please report snow or ice by calling 412-262-1988, posting to the NWS Pittsburgh Facebook page, or using Twitter @NWSPittsburgh && $$ Winter Weather Advisory URGENT - WINTER WEATHER MESSAGE National Weather Service Baltimore MD/Washington DC 403 AM EST Sat Nov 30 2019 MDZ501-502-WVZ501-503-504-301715- /O.UPG.KLWX.WS.A.0007.191130T2300Z-191201T1700Z/ /O.NEW.KLWX.WW.Y.0027.191201T0000Z-191201T1700Z/ Extreme Western Allegany-Central and Eastern Allegany- Western Grant-Western Mineral-Eastern Mineral- 403 AM EST Sat Nov 30 2019 ...WINTER WEATHER ADVISORY IN EFFECT FROM 7 PM THIS EVENING TO NOON EST SUNDAY... * WHAT...Freezing rain expected. Total ice accumulations of around two tenths of an inch. * WHERE...In Maryland, Extreme Western Allegany and Central and Eastern Allegany Counties. In West Virginia, Western Grant, Western Mineral and Eastern Mineral Counties. * WHEN...From 7 PM this evening to noon EST Sunday. * IMPACTS...Difficult travel conditions are possible. PRECAUTIONARY/PREPAREDNESS ACTIONS... Slow down and use caution while traveling. Prepare for possible power outages. When venturing outside, watch your first few steps taken on steps, sidewalks, and driveways, which could be icy and slippery, increasing your risk of a fall and injury.

IAD reported at 6:52 an intrahour low of 17.

My swag: BWI: 18 DCA: 15 IAD: 21 RIC: 10 Tiebreaker (SBY or LYH): SBY 8 ((and hoping for much less))

DCA did hit 32 at 2.52 am on 9 Nov.

WTOP 103.5 is reporting on the Chain Bridge water main break. Arlington County schools and offices are closed. The break affects much of Arlington County and NW DC. Arlington has announced a boil water advisory.

Have you dug out your parkas out of the attic/elsewhere yet? I have...

It'll be close. Right now NWS forecasts DCA to hit 33 at midnight, 2 at 3 am on 9 Nov.

If I had gone with my guesstimate of climo…. BWI//IAD Halloween DCA/RIC Veterans Day I might be slightly close.

Prepare to defrost or scrape this morning. Although DCA hit only 39, Andrews AFB reported 32 around 6 am.

As of 554 am, RIC hit 33 degrees. Let's see what the 754 6-hour measurement shows.

GFS is claiming next freeze chances for DCA and RIC start next weekend, with a strong likelihood of freezing by the middle of the following week. That said, it IS the GFS...

The 6 hour obs list at 7:54 said BWI was max 36, min 32.

Dulles hit 32 on 2 Nov at 3:52 am. BWI was at 33. The DCA heat island was at 40. Richmond at 37.

LWX just posted freeze watches for early Saturday, Including DC. ((I don't think DCA will freeze)). URGENT - WEATHER MESSAGE National Weather Service Baltimore MD/Washington DC 407 AM EDT Fri Nov 1 2019 District of Columbia-Frederick MD-Carroll-Northern Baltimore- Southern Baltimore-Prince Georges-Anne Arundel-Calvert- Northwest Montgomery-Central and Southeast Montgomery- Northwest Howard-Central and Southeast Howard-Northwest Harford- Southeast Harford-Fairfax-Arlington/Falls Church/Alexandria- Western Loudoun-Eastern Loudoun- Including the cities of Washington, Frederick, Ballenger Creek, Eldersburg, Westminster, Reisterstown, Cockeysville, Baltimore, Bowie, Suitland-Silver Hill, Clinton, College Park, Greenbelt, Laurel, Camp Springs, Glen Burnie, Annapolis, Severn, South Gate, Severna Park, Arnold, Odenton, Chesapeake Beach, Huntingtown, Dunkirk, North Beach, Lusby, Prince Frederick, Germantown, Damascus, Bethesda, Rockville, Gaithersburg, Silver Spring, Lisbon, Columbia, Ellicott City, Jarrettsville, Aberdeen, Reston, Herndon, Annandale, Centreville, Chantilly, McLean, Franconia, Arlington, Alexandria, Falls Church, Purcellville, Leesburg, Ashburn, and Sterling 407 AM EDT Fri Nov 1 2019 ...FREEZE WATCH IN EFFECT FROM LATE TONIGHT THROUGH SATURDAY MORNING... ...WIND ADVISORY HAS EXPIRED... * WHAT...Sub-freezing temperatures as low as 30 possible. * WHERE...The District of Columbia; northern, central, and southern Maryland; and northern Virginia. * WHEN...From late tonight through Saturday morning. * IMPACTS...Frost and freeze conditions could kill crops, other sensitive vegetation and possibly damage unprotected outdoor plumbing. * ADDITIONAL DETAILS...Winds gusting up to 30 mph will be likely this morning. PRECAUTIONARY/PREPAREDNESS ACTIONS... Take steps now to protect tender plants from the cold. To prevent freezing and possible bursting of outdoor water pipes they should be wrapped, drained, or allowed to drip slowly. Those that have in-ground sprinkler systems should drain them and cover above- ground pipes to protect them from freezing. URGENT - WEATHER MESSAGE National Weather Service Baltimore MD/Washington DC 407 AM EDT Fri Nov 1 2019 Charles-St. Marys-Nelson-Albemarle- Prince William/Manassas/Manassas Park-Stafford-Spotsylvania- King George- Including the cities of St. Charles, Waldorf, Lexington Park, California, Lovingston, Charlottesville, Dale City, Manassas, Woodbridge, Lake Ridge, Montclair, Falmouth, Fredericksburg, and Dahlgren 407 AM EDT Fri Nov 1 2019 ...FREEZE WATCH IN EFFECT FROM LATE TONIGHT THROUGH SATURDAY MORNING... * WHAT...Sub-freezing temperatures as low as 33 possible. * WHERE...In Maryland, Charles and St. Marys Counties. In Virginia, Nelson, Albemarle, Prince William/Manassas/Manassas Park, Stafford, Spotsylvania and King George Counties. * WHEN...From late tonight through Saturday morning. * IMPACTS...Frost and freeze conditions could kill crops, other sensitive vegetation and possibly damage unprotected outdoor plumbing. (snip)

And from AKQ: (snip) .SHORT TERM /6 AM THIS MORNING THROUGH SUNDAY/... As of 345 PM EDT Thursday... Sunny and much cooler Fri with highs in the mid to upper 50s. Around 60 is possible near the coast. Expect breezy conditions in the morning, but winds will decrease by afternoon as the high builds in and the pres gradient relaxes. Cool high pres will bring the coldest night of the season to date Fri night/Sat morning. Lows around freezing (well) inland...m-u30s central to lower to mid 40s along the coast. Potential frost/freeze headlines will be contemplated by proceeding shifts as we get closer. Continued cool and dry on Sat w/ highs in the upper 50s to lowers 60s. Another weak front pushed south late Sat night bringing another sot of cool air and colder temps Sunday with high only in the low to mid 50s. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... As of 250 PM EDT Thursday... Cool high pressure becomes centered over the area Sunday evening- Sunday night before moving offshore by Mon aftn. Sun night looks like the coldest night of the season (so far), with lows in the low- mid 30s inland/upper 30s-mid 40s close to the immediate coast. Will continue to monitor the possibility of a freeze (mainly W of I-95).

From the latest LWX forecast: (snip) As winds subside tonight, radiational cooling will be excellent. With dewpoints in the 20s-lower 30s, stage set for a possible freeze everywhere except urban downtowns/near the Bay/Potomac. Will issue a Freeze Watch for area where growing season continues as forecast lows at or below freezing areawide except as noted above. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... High pressure this weekend, with a reinforcing trough axis/surface cold front Saturday night. Will be struggling to reach 50 degrees Sunday. If the growing season doesnt end by Saturday morning, Sunday night`s lows will likely do it. There could also be some upslope snow showers Saturday night-Sunday morning as well.

IAD is reporting it went from 78 at 19:52 to 44 at 2:52. DCA went from 77 to 48.

From the latest LWX advisory: (snip) All the ingredients remain in place for a potentially dangerous severe weather event tonight. MLCAPE values increase to 500-1000 j/kg due to daytime heating in spite of the clock and calendar; there is more than ample shear present as a 60-70 kt low level jet develops in advance of the sharpening/negatively tilting trough axis; the area will be situated in the right-rear quadrant of the upper jet; and the baroclinic zone across the frontal boundary will be dramatic. These factors suggest that a squall line/QLCS should develop near the front, with straight line winds as the primary concern. However, the intensity of the wind/shear also suggests that spin-up tornadoes cannot be ruled out, as highlighted by STP index (HREF ensemble mean ranging from 2-5). THere is general consensus on timing too, from 21-00Z in the mountains, to 03-06Z near the Bay. An Enhanced Risk of severe weather remains in place from SPC.