batmanbrad

one last band trying to move E/NE from Loudoun County, if it holds together could give much of Central/Southern MoCo a bit more accumulation in the next hour or so.

measured about 1.5" on my deck railing, not as accurate as a snowboard measure, but considering a bit of compaction possible I'll take it! Wasn't expecting more than an inch up this far (NE Gaithersburg, close to Laytonsville)

have to say that overall this was fairly well predicted by the models, Euro gets props for having been the earliest and fairly consistent to predict that places even north of DC up to around I70 would get measurable stuff... and the timing of when it would begin and (soon) end was accurate as well. Some of the other models were late to the northern shift but did catch on as we got closer to the event.

clearly they built that stretch of I-70 to coincide with the northern extent of the green portion of the precip! Pretty much in line with much of the model predictions as to where the cutoff would set up?

18Z RGEM about the same as previous run, maybe just a hair better but mostly noise I think

let's see if King Euro comes back north as well and joins the rest of the 12Z model suite. It might as well finish what it started, right?

yep, no more snow for us on the 18Z, everything shifted significantly north - northern New England and interior New York get a good snow from this run.

and now the 12Z GooFus has backed that up to 12/3!

nice break in the clouds over MoCo, full sun here in Gaithersburg (near Laytonsville)!

12km NAM doing its NAM thing on us, look at all that 1+" purple!

latest 18Z GFS painting over .75" QPF for much of our area, has been trending upward:

BWI: 17.8 DCA: 11.4 IAD: 19.5 RIC: 8.5 SBY: 7.5

is it stationary because something of an equilibrium has been (temporarily) reached between the competing steering flows?

both HAFS-A and HAFS-B (12Z) models showing a direct hit to Kingston with around 940mb, yikes

given that it comes in around Halloween, it would seen that the CMC run is trying to look really... scary. Presumably the 0Z run will be like Monty Python says ("And now for something completely different")

even more nastiness, yikes: Flash Flood Statement National Weather Service Baltimore MD/Washington DC 540 PM EDT Sat Jul 19 2025 DCC001-MDC031-033-VAC059-200015- /O.CON.KLWX.FF.W.0115.000000T0000Z-250720T0015Z/ /00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/ District of Columbia DC-Montgomery MD-Prince Georges MD-Fairfax VA- 540 PM EDT Sat Jul 19 2025 ...FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 815 PM EDT THIS EVENING FOR THE NORTHWESTERN DISTRICT OF COLUMBIA AND SOUTHEASTERN MONTGOMERY, PRINCE GEORGES AND FAIRFAX COUNTIES... At 540 PM EDT, emergency management reported thunderstorms producing heavy rain in Emergency management reports water rescues in Takoma Park and Silver Spring area. Flood sensors on SLigo Creek at SLigo Creek Parkway and New Hampshire Avenue show a 10 ft rise in 30 mins. . Between 2 and 3.5 inches of rain have fallen. The expected rainfall rate is 1 to 2 inches in 30 minutes. Additional rainfall amounts of 1 to 2 inches are possible in the warned area. Flash flooding is already occurring. HAZARD...Life threatening flash flooding. Thunderstorms producing flash flooding. SOURCE...Emergency management reported. IMPACT...Life threatening flash flooding of creeks and streams, urban areas, highways, streets and underpasses. Some locations that will experience flash flooding include... Bethesda... College Park... Greenbelt... Langley Park... Beltsville... Bladensburg... Fort Totten... American Legion Bridge... University of Maryland... Potomac... North Bethesda... Landover... Hyattsville... Takoma Park... Wolf Trap... East Riverdale... Great Falls... Adelphi... Kemp Mill... New Carrollton...

Radarscope has a 2" hail marker on it too edit actually that's the cell SW of Point Of Rocks

WPC upped parts of our area to MDT risk for flooding per their late morning update...

pretty large sized watch area too...

and there's our watch as well, just popped up on my phone.

DCA: 103 IAD: 101 BWI: 102 RIC: 100

at least for now there's what appears to be a decent couplet on that cell north of Winchester... TVS indication per RadarScope

not only severe, but WPC says flooding could be a concern too: Mesoscale Precipitation Discussion: #0227 (Issued at 635 PM EDT Mon May 05 2025 ) MPD Selection Mesoscale Precipitation Discussion 0227 NWS Weather Prediction Center College Park MD 635 PM EDT Mon May 05 2025 Areas affected...portions of eastern VA into the DMV and far eastern WV Concerning...Heavy rainfall...Flash flooding possible Valid 052235Z - 060300Z Summary...Training convection will be capable of hourly totals of 1-3" with short-term (3-hr) totals as high as 2-4". Isolated to scattered instances of flash flooding are possible (and may be locally significant in sensitive urban/mountainous terrain). Discussion...Radar and GOES-East satellite imagery indicate the proliferation of convection across portions of eastern VA/NC over the past several hours, moving fairly rapidly (~25 kts) towards the N-NE within nearly unidirectional flow on the eastern periphery of a large, deep layer (850-200 mb) closed low centered over IL/IN/KY. The mesoscale environment in the vicinity and downstream of the aforementioned convection is characterized by SBCAPE of 1000-2000 J/kg, PWATs of 0.8-1.3" (between the 75th and 90th percentile, per IAD sounding climatology), and deep layer (0-6km shear) of 20-40 kts (per 22z SPC SFCOA analysis). The strongest cells have been capable of impressive instantaneous rainfall rates of 3-5"/hr (per MRMS estimates), which has resulted in estimated hourly rainfall totals of up to 2.5" (where deeper convective cells have been able to occasionally train, mainly to the east of I-95 in eastern VA). Recent hi-res CAMs have not handled the evolution of convection particularly well, and recent observational trends (including continued overshooting/cooling cloud tops via GOES-East imagery) suggest that localized hourly totals of 1-3" will continue to manifest farther north (into the more sensitive DMV region) with storm propagation (as a pool of 1500-2000 J/kg of SBCAPE remains untapped). While both of the hourly updating CAMs (HRRR/RRFS) are handling the convection poorly, the 18z HREF suite does still give a good idea of the potential for excessive rainfall through 03z (with 40-km neighborhood probabilities for 2" and 3" exceedance of 20-30% and ~10%, respectively). Given locally sensitive terrain (per FFGs as low as 0.75-1.50" and 1.50-2.50" for 1-hr and 3-hr periods, respectively) over urbanized terrain along and near I-95 and over portions of the Appalachians in the vicinity of northern VA, western MD, and far eastern WV, isolated to scattered instances of flash flooding are possible (and may be locally significant, should 2-4" totals occur over the most sensitive localities). Churchill ATTN...WFO...AKQ...CTP...LWX...RAH... ATTN...RFC...MARFC...SERFC...NWC... LAT...LON 39827743 39597667 39037647 37767669 36447699 36217739 36777738 37437742 38277778 39617833

might have been a "false alarm", but I was getting a TVS on the cell NW of Leesburg on RadarScope for a bit, but it seems to have disappeared.

I'm sure DT loves this run, both for it being a jack in his area and because he worships the Euro.