vortex95

Pasadena MD 7/5. Listen w/ headphones/earbuds for the full effect! https://www.facebook.com/reel/2524504421303837

Pasadena MD 7/5. Listen w/ headphones/earbuds for the full effect! https://www.facebook.com/reel/2524504421303837

BDR 1.23" so far as of 4am. Radar has the look CoastalWx *hates* in the winter b/c he knows there will be a sharp line between S+ and "diamond dust!" And the 06z HRRR squishes things S more. 00Z RRFS was more N, but lacks the crazy QPF. HRRR shows some mesoscale thingee forming in ern LI Sound and tracking E. That has the big QPF but largely stays offshore except for MVY/ACK. Also, half-decent backlash comma head pcpn at the end. Sfc only low goes from 1015 to 1009 mb, but is tight/coherent and sets up a small solid gradient along the S Coast and CC. Wind pretty good for July. Sustained max 25G40KT shown front end and 30G45KT max in the rear GON-CQX-PYM. Li'l July Nor'easter! 06z 3/12km NAMs way N. So fcst uncertainty quite high still, esp. given the event is already underway.

Could have been some gustnadoes in there, but yes, it was trying to "derecho." Let's makes nouns into verbs for weenie sake! CoastalWx does things this except he omits verbs such as, "WE SNOW!" He also likes to say, "I HAZ..."!

Just by going by sat imagery alone and Bavi's clear and large eye, the centroid of the eye looks like it passed about 6 nm N of the N tip of Rota using EIR. VIS is tougher b/c you have mesovorts within the eye rotating around one another. Each mesovort has its own pressure minimum, and one of those may have crossed Rota. Just curious how this is counted. It is obviously a direct hit but does it count as a landfall? Rota clearly got in the eye, but the centroid was just N. Looking at radar at is closest, looks like the centroid just passed to the N. Radar is better than sat in this case b/c even at 14N, there is a bit of a parallax error in geostationary imagery.

Just by going by sat imagery alone and a very clear and large eye, the centroid of the eye looks like it passed about 6 nm N of the N tip of Rota using EIR. VIS is tougher b/c you have mesovorts in within the eye rotating around one another. Each mesovort has its own pressure minimum, and one of those may have crossed Rota. It will be very interesting to see the pressure measurements on Rota b/c getting such measurement for a super typhoon at its peak is rare.

When you have light/weak winds 500 mb and below, chaotic storm motion is common. Mesoscale factors such as storm rotation, outflow boundaries, and cell back-building (discrete propagation) can take front and center, so you get all sorts of odd storm motion. This is basically what you see almost every day in the summer in the Southeast and Gulf Coast states! We saw the same thing today, esp. w/ that svr storm W of Columbia. Hardly moved at first and then started to drift/build S. I attached a short loop of the W of Columbia svr storm. Also, the CG LTG was intense w/ this storm (plot attached). I think this storm was briefly a supercell before it gusted out. It split as well, indicating rotation. See the storm to its N moving NE fairly quickly? That's a left (anticyclonic) supercell split! You can tell b/c of it flared look NW to SE yet moving NE. When a supercell splits, the mesocycylonic split slows down and turns more to the right, while the anticyclonic split accelerates and moves more to the left (in the Northern Hemisphere).

Ask CoastalWx about such an experience when he lived in Dorchester!

Not be a "dampener" on the event... Two things should mitigate the extent/severity of the flooding: 1) Antecedent conditions are very dry and water levels in lakes, rivers, and streams are low. This is huge factor in this case. How wet or dry antecedent conditions are in a region when big rains occur can make the difference between modest flooding and record flooding! So in this case, we have a plus. 2) The event will be drawn out over 48 hr. 6" of rain in 6 hr is *not* the same as 6" in 48 hr, as one example, at least when it comes to flash flooding. For large-scale river flooding, this often is a problem, but from item 1 above, rivers are starting low so there is considerable buffer before sig flood stage. Not that there will not be any flooding, but the point here is that not all big events are created equal in terms of potential impact. Some may go, "8" of rain coming???!!! OMG, that means massive flooding!!!" Not necessarily. This is why I emphasize context and perspective so much. W/ wx events, and many other things for the matter, it is *not* "one-size-fits-all!" The ppl out there who know their stuff and how to handle/present data/info will adhere to this essential guideline. As I have mentioned before, communication of risk/threats, not forecast model skill, are the biggest challenge we face these days when it comes to wx events.

You can really see the blossoming of the R+ by 48 hr on the 06z HRRR. This corresponds w/ a sig ramp up of S and SE winds 925-700 mb (40-45 kt) and a nose of 2"+ PWATs. WCB/WAA wing in summer?, CoastalWx? (don't say MEH!).

Last evening, a PDS SVR was issued for Block Island. However, the warning stated 60 mph gusts. That is not PDS level (74 mph I believe is). Any insights?

RW++ w/ no thunder observed? Let us know! The HRRR ydy suggested stuff would linger/redevelop after midnight today, but it was right along the S Coast. It's more N, and look in CT and far SW MA. You have these li'l cells developing, moving SE, while high level anvil pcpn areas are moving E! "Pseudo-PRE" event for CT last 12 hr for the big rains coming??

Yes, a 48 hr event will lessen overall impact. 6" of rain in 6 hr is not the same as 6" in 48 hr, at least not for flash flooding. For larger-scale river flooding, this is not the case. However antecedent conditions being so dry and water levels low, this should mitigate large-scale river flooding. Not that there will be none, but "it could be much worse!" Cliche I know, but sometimes it does fit a scenario well when trying to quantify impact. I always go back to VT w/ Floyd from 1999 and Irene from 2011. Similar big rains in VT from both, but Floyd flooding was not big time, but Irene was. Why?, antecedent conditions. Summer of 1999 was one of the driest on record for NNE, and summer of 2011 one of the wettest. Or going way back, Connie and Diane 1-2 punch in a week Aug 1955. Connie "primed" things, and Diane sealed it. Worst flooding in SNE on record I think.

Anywhere near the May 15, 2018 level? How would you rate?

Sharp reflectivity gradient on the leading edge --classic sign of strong straight-line winds!