arlwx12

Haze showing up at DCA. Current DC air quality listed as 62 (moderate). NWS forecasts air quality to worsen today... ...AIR QUALITY ALERT IS IN EFFECT FOR THURSDAY JULY 16 2026... The Metropolitan Washington Council of Governments and District Department of Environment has issued a Code ORANGE Air Quality Alert Thursday for the District of Columbia. A Code Orange Air Quality Alert means that air pollution concentrations within the region may become unhealthy for sensitive groups. (snip)

Dulles still in the running for warm low for date. BWI just missed.

At least the DC area air quality is not that of Detroit... Detroit registers worst air quality in the world among major cities as wildfire smoke blankets Michigan DETROIT, Mich. (News 10) - Heavy wildfire smoke from Canada and Minnesota continues to settle into Lower Michigan, causing Detroit to have the worst air quality in the world among major cities Thursday morning. Detroit’s air quality index (AQI) was rated at 684 as of 3:30 a.m. Thursday, according to IQ Air which tracks air quality ratings across the world. Air quality is ranked in these categories: 0-50 = Good, 51-100 = Moderate, 101-150 = Unhealthy for sensitive groups, 151-200 = Unhealthy, 201-300 Very unhealthy, 301+ = Hazardous (snip)

In the latest AFD from LWX... National Weather Service Baltimore MD/Washington DC 400 AM EDT Sat Jul 4 2026 .WHAT HAS CHANGED... Given an uptick in today`s heat index forecast, have upgraded to Extreme Heat Warnings across north-central Maryland down across the eastern West Virginia Panhandle into the Shenandoah Valley. For today`s convective threat, the Storm Prediction Center has upgraded to an Enhanced Risk for severe thunderstorms across locations east of the Blue Ridge Mountains. (snip) Before convection enters the picture, it will be another day of record warmth across the Mid-Atlantic region. Using 850-mb temperatures as a proxy, forecast readings should be around 22-23C which dry adiabatic mixing favors another 100 degree day. Adding continued tropical moisture in place will support heat indices pushing into the 105 to 110 degree range. Extreme Heat Warnings are in effect from 10 AM until 9 PM for areas east of the Blue Ridge. (snip) Although vertical shear is only around 20 to 25 knots, any storms able to tap into the robust instability will be capable of damaging winds. Some of this could be locally destructive with gusts up to 60 to 75 mph. (snip) The primary signal east of the Blue Ridge is in the 3-9 PM timeframe, slightly earlier to the west. Damaging to locally destructive winds are the main threat, with any chance for large hail being minimal given the summertime freezing levels. (snip)

Hear=t advisories posted for virtually the entire LWX area. WWA Summary for Heat Advisory Issued by LWX

Severe thunderstorm watch posted further south/east from DC, including Calvert and St Mary's.

Visibility down to about 1/2 mile in the downpour near DCA. edit: now more like 1/4 mile.

Heat advisory up for parts of the DC/Baltimore metros and points east including the western shore of the Chesapeake Bay.

LWX's daily reports showed a T of snow at DCA and IAD, tying records.

Looks like the warm water helped keep DCA (and a few other spots "on" the water) well short of freezing. A few other locations may also have escaped. But IAD hit 27, BWI 30

I prepared for tomorrow morning by looking at a list of DCA "latest last freezes" through 2023. The most recent one on April 10 (or later) was 2016. More on this if DCA does indeed hit freezing tomorrow (it MIGHT not).

In 2025, "last freeze" dates at DCA/IAD/BWI: DCA: March 3 IAD: April 9 BWI: April 9

Warnings for an upcoming freeze all across the region. Only SE Virginia is spared, and of course the mountains don't get freeze warnings yet. ((Sorry for those who might have thought Tax Day signalled "safe to plant" starting time for tender stuff.))

URGENT - WEATHER MESSAGE National Weather Service Baltimore MD/Washington DC 1159 PM EDT Sat Apr 18 2026 MDZ011-504-506-508-VAZ036-037-053-055-056-527-191200- /O.NEW.KLWX.FZ.A.0003.260421T0600Z-260421T1400Z/ Southern Baltimore-Central and Southeast Montgomery-Central and Southeast Howard-Southeast Harford-Nelson-Albemarle-Fairfax- Stafford-Spotsylvania-Central and Southeast Prince William/Manassas/Manassas Park- 1159 PM EDT Sat Apr 18 2026 ...FREEZE WATCH IN EFFECT FROM LATE MONDAY NIGHT THROUGH TUESDAY MORNING... * WHAT...Sub-freezing temperatures as low as 29 to 32 degrees possible, especially northwest of I-95. * WHERE...In Maryland, Central and Southeast Howard, Central and Southeast Montgomery, Southeast Harford, and Southern Baltimore Counties. In Virginia, Albemarle, Nelson, Spotsylvania, Central and Southeast Prince William/Manassas/Manassas Park, Fairfax, and Stafford Counties. * WHEN...From late Monday night through Tuesday morning. * IMPACTS...Frost and freeze conditions could kill crops, other sensitive vegetation and possibly damage unprotected outdoor plumbing. PRECAUTIONARY/PREPAREDNESS ACTIONS... Take steps now to protect tender plants from the cold.

DCA also briefly hir 90 around 1 pm. 88 as of 2:45.