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high risk

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Everything posted by high risk

  1. high risk
    Yeah, the art of figuring out which type of watch, where / when to place them, and make them connect is referred to as "boxology" by the SPC forecasters.
  2. high risk
    HRRR has been consistent with a few cells forming over Montgomery County and vicinity after 6pm and then affecting DC and points north as a line segment. It may be wrong, but it's sticking to its guns. The supercell composite has looked good to the south and southeast of here all day, so I understand the tornado watch down there. I think that SPC just decided to go with one big tornado watch instead of a tornado watch for southern VA and eastern NC and a severe box for the DC area..
  3. high risk
    Convection now firing in the eastern WV panhandle, very consistent with recent HRRR forecasts. If there is going to be a show, and again, it would mainly be DC and points northward, this is the start of it. I still think that the lack of heating precludes a much more significant event, but the HRRR says that storms will be strong if we can get to near 80.
  4. high risk
    As you noted in the MD you posted, though, the backed low-level winds are in the eastern part of that entire MD area. It's not a north-south thing. Over the next few hours, low-level winds in the DC area up through central PA and west-central NY are clearly progged to veer, which would make the tornado threat very low (unless there is some interaction with a leftover boundary). Over the Delmarva and NJ up through eastern NY, the hodographs may indeed support a low-end tornado threat. Of course, initiation has already happened over central PA, while we're going to have to wait a while in the DC metro area (and I as noted earlier, the HRRR only likes areas from DC to the north, and not until dinner time), so I have no clue how SPC will issue boxes today.
  5. high risk
    I'm going to toss the HiResWs (which don't assimilate ongoing rain) and focus on the NAM Nest and HRRR. Both show some limited airmass recovery this afternoon generally north of DC and generate at least a few storms across northern and central MD towards dinner time. Surface winds are veered, so unless a storm finds an outflow boundary, the tornado threat is likely lower, but IF we can get heating, the shear would support at least isolated instances of damaging wind.
  6. high risk
    Still a ton of uncertainty in the 00Z CAM suite. Several solutions fire convection late morning / midday.
  7. high risk
    The HRRR keeps wanting to kill it just before it reaches the Potomac. That said, while I think that there is a limited life for this thing, the HRRR is slow with the movement, so I could see it making it a bit further east.
  8. high risk
    Yeah, that line will still pack a punch for at least several more hours as it moves east across northern VA and western MD. The question is how far east it can advance as it encounters decreasing instability. Different HRRR cycles have shown it dramatically weakening in the western suburbs, as it crosses the Potomac, or over central MD. Some severe wind into at least part of the immediate DC area is certainly on the table.
  9. high risk
    Everything you wrote about the HRRR and NAM Nest is correct, but I don't think that tomorrow is about mixing. It's about clouds and convection from lead shortwaves. The NAM Nest is a round of storms late tonight and a second round in the very early afternoon, but the second round is mostly south and southeast. The northern areas therefore recover enough during the day for a good round of storms at the end of the day. The HRRR has the early morning stuff, and then round 2 around midday is more expansive. It still warms up behind it, but the surface winds veer, and there is little convergence along the front except in far northern MD, where the HRRR does have a round 3 at the end of the day. I won't go through every CAM, but the keys are heating and wind direction by mid afternoon. If we are heating and the winds are southwesterly, a big late day show is unlikely. If we are heating and the winds are more southerly, I think we'll have at least some coverage of SVR.
  10. high risk
    Put me down for 5/15/15. If we went entirely off of the NAM Nest, it would be an ENH for sure, but several CAMs have some morning or midday convection that ruin the lapse rates.
  11. high risk
    Seems like the GFS wants to break out convection during the morning which kills lapse rates and heating later in the day. The NAM is dry in the morning, and noted by @yoda, the environment at peak heating looks quite good, with nice backing of the low-level winds too. GFS does seem to be a bit of an outlier. My guess is that unless the 00Z ECMWF looks like the GFS, we'll have a Day 3 SLGT when we wake up Saturday morning.
  12. high risk
    I"m surprised. We heard thunder in North Laurel and then again in the Oakland Mills area of Columbia. We were also able to see lightning from the cell up near York after dark. Some signal in the CAMs for a few storms around later tonight, although I'm not sure what would trigger them.
  13. high risk
    It's worth noting that SPC used to be very liberal with issuing Moderate Risks. We had 3 here in a two-week period in some year in the early 2000s. They eventually added the Enhanced category so that they could save the Moderate for legitimate higher-end events.
  14. high risk
    Yeah, that was a cool event. There were definitely several tornadoes in the local area, although none of them were strong, as I recall. One tracked very close to Fort Meade.
  15. high risk
    Monday definitely has potential. SPC hinted at some timing issues in their discussion, and I would definitely prefer the faster progression of the upper wave depicted on the 00Z ECMWF.
  16. high risk
    That watch box comes further east than I expected
  17. high risk
    Definitely no more of the large region-wide area of rain that we had this morning, but some places are still going to get quite wet early this afternoon. There is some good agreement in the guidance for several areas of steadier showers, and the radar is starting to fill in a bit over northern VA.
  18. high risk
    Maybe? The GFS dries things out quickly, but most of the regional models stay wet until much later in the afternoon. But yeah, either way it won't be a good afternoon for outside stuff.
  19. high risk
    After looking at the evening guidance, I still have little confidence in a Saturday forecast, although the trend for those of us east of the Potomac seems to be wetter.
  20. high risk
    That's a very bullish forecast. It certainly seems like the best chances of heavy weekend rain are in the western and southwestern parts of the area, but depending on model of choice, heavy rain is far from a lock even there:
  21. high risk
    Right, but northern stream events here early in the season often struggle with instability, as it's tough to get good low-level moisture north at this time of year without some help.
  22. high risk
    Not only were there a couple of confirmed tornadoes in Garrett County Saturday, but the SPC storm reports list effectively shows a regional mini-outbreak. Quite remarkable for an event without a watch box.
  23. high risk
    models are very emphatic that the warm air is going to be confined to areas well south and west of DC. The trends in the HREF to eliminate the SVR risk in the DC area are quite clear: 12Z yesterday: 00Z today:
  24. high risk
    The HRRR was really the only model that ever went all in on this scenario, but it really backed off yesterday evening.
  25. high risk
    I think there is some clear potential for higher end events like that in the LWX CWA, but it's going to be limited to the extreme southern part of their area unless the models start moving the warm sector back further north
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