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George BM

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Everything posted by George BM

  1. Forecast Discussion Thursday, September 14, 2023 3:28PM EDT Our most significant and dangerous flash flood threat in more than 50 years will begin by this evening. Through Monday parts of the region may see more than half-a-years’ worth of rainfall. A Flash Flood Watch is in effect for the entire Washington/Baltimore Metropolitan region from 6PM this evening through Saturday though this will almost certainly end up being extended through at least Monday as forecast details for Sunday and Monday become clearer. With a near record strong WAR, a deep trough over the Ohio Valley and moisture from Margot streaming north from the Caribbean and western Atlantic east of Florida, Pwats will rise to the 2.25”-2.5”+ range from this evening through the beginning of next week. Clusters and trains of tropical downpours/storms will move north over the region at all times of the day. With limited sunshine and high moisture content temperatures will probably only vary by about 5-10F from daytime highs to nighttime lows (Low/mid 80s and mid/upper 70s respectively). Dewpoints will remain in the mid/upper 70s throughout the period. As far as severe weather goes there will be a daily threat of gusty winds and even a brief tornado or two especially with any transient supercells given CAPE values of 1500+ J/kg and effective SRH of 150-200 m2/s2. Lack of downdraft CAPE will prevent a bigger wind threat with storms though there may be a couple of mesovort maxes that move from south to north over the region over the next couple of days which may enhance both deep-layer and low-level shear leading to a locally higher risk of a brief tornadic supercell as well as bowing segments allowing for damaging/near-severe wind gusts and a QLCS tornado threat. The main threat by far, however, will be the very heavy rainfall rates with these downpours and storms. Given the aforementioned Pwats and CAPE any location that gets under a band of storms that trains over the area for an extended period of time may receive several inches of rain within a few hours leading to major flash flooding. Even areas that don’t get stuck under a train of convection as frequently if at all will see many individual storms or clusters over the next couple of days resulting in several inches of rain and flooding concerns. All of the above does not even account for when Margot will finally move north into the region by the Sunday PM/ Monday AM timeframe. More on that below. Models are coming into much better agreement that by sometime Sunday Margot will make landfall along the Carolina coastline being pulled north fairly rapidly by the strong ridge of high pressure to the east and deep trough of low pressure to the west. While the exact track and timing of the center are still being ironed out, as this is still 3 days away from occurring, it’s now looking very likely that at least a majority of the Baltimore/Washington region may experience significant impacts from Margot. Ahead of Margot on Sunday the low-level shear that will be with us through the weekend will further increase leading to a higher likelihood of tornadic supercells. As the center approaches and moves over the region a solid shield of heavy rain will move through leading to an additional several inches of rain. The biggest uncertainty that remains with Margot is how strong the tropical system will be at landfall along the Carolina coast as anything ranging from a tropical storm to, in the worst-case scenario, a major hurricane is plausible. This will determine the difference between getting several inches of rain with gusty winds Sunday into Monday OR damaging to hurricane-force wind gusts teaming up with the heavy tropical rains leading to widespread tree and structural damage. We will continue to monitor this potentially catastrophic situation with frequent updates over the next several days. Forecaster Wannabe: George BM
  2. There may be a beautiful sunset coming up later next hour.
  3. Oh I know... it's just that it made all those turns just to hit both Bermuda and Nova Scotia. Usually they just go roughly due north between the two locations.
  4. I mean Bermuda and Nova Scotia have been tropical system magnets in recent years so...
  5. It's actually 968mb at the surface on that sonde... there's just no wind data at the very surface for some reason... so probably good for 967/966mb.
  6. Have fun!... obviously ditto to what Mappy said above as well.
  7. Best of luck to your parents.
  8. 000 WTNT65 KNHC 271513 TCUAT5 Tropical Storm Idalia Tropical Cyclone Update NWS National Hurricane Center Miami FL AL102023 1015 AM CDT Sun Aug 27 2023 ...DEPRESSION STRENGTHENS TO A TROPICAL STORM... Observations from a NOAA Hurricane Hunter aircraft indicate that Tropical Depression Ten has strengthened into Tropical Storm Idalia. The maximum winds are estimated to be 40 mph (65 km/h) with higher gusts. SUMMARY OF 1015 AM CDT...1515 UTC...INFORMATION --------------------------------------------------- LOCATION...19.9N 85.8W ABOUT 80 MI...135 KM ESE OF COZUMEL MEXICO MAXIMUM SUSTAINED WINDS...40 MPH...65 KM/H PRESENT MOVEMENT...E OR 90 DEGREES AT 2 MPH...4 KM/H MINIMUM CENTRAL PRESSURE...996 MB...29.41 INCHES $$ Forecaster Pasch
  9. 97/68 currently at IAD tying the record high for today.
  10. Looks like we have a chance of elevated convection/thunder w/ the main chances coming tonight/early tomorrow morning and again early Friday morning. NW-flow regime... elevated style.
  11. This morning the air was uncomfortable for serious running, pre-dawn. Now it's only 5-7F warmer than it was during the 5am hour w/ dewpoints nearly 20F lower w/ the breeze making it feel like September. Overall, a fairly similar day to this past Friday. Currently IAD at 82/49.
  12. Yeap. 000 WTNT33 KNHC 202053 TCPAT3 BULLETIN Tropical Storm Franklin Advisory Number 1 NWS National Hurricane Center Miami FL AL082023 500 PM AST Sun Aug 20 2023 ...TROPICAL STORM FRANKLIN FORMS IN THE CARIBBEAN SEA.. ...TROPICAL STORM WATCHES ISSUED FOR THE SOUTH COAST OF HAITI AND THE DOMINICAN REPUBLIC... SUMMARY OF 500 PM AST...2100 UTC...INFORMATION ---------------------------------------------- LOCATION...14.6N 67.1W ABOUT 270 MI...435 KM SSE OF ISLA SAONA DOMINICAN REPUBLIC ABOUT 270 MI...435 KM SSW OF SAN JUAN PUERTO RICO MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H PRESENT MOVEMENT...WNW OR 290 DEGREES AT 14 MPH...22 KM/H MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES .....
  13. That's one advantage of living relatively isolated from others.
  14. A little bit of everything for all preferences verbatim.
  15. Severe Thunderstorm Watch coming out until 9pm for much of the area.
  16. ~1.45" in the gauge from yesterday. Brief gusts into the low 40s(mph) w/ the initial line... pedestrian IMBnFY.
  17. This got lost in the severe tracking but that 12z GFS run for Friday the 18th was total lolism. Temps in the mid 80s+ at the crack of dawn w/ 110+F highs across the region during the afternoon. OBVIOUSLY 18z is more realistic with no Desert SW-like heat.
  18. Going on 270 posts in the severe thread today w/ storms not even in the main region yet. Impressive winter-like activity.
  19. It's actually from the same link you shared yesterday. Thanks for that, btw.
  20. ...OH Valley to Mid-Atlantic to the southern Appalachians and Carolinas... Scattered showers and isolated storms are forecast to be ongoing over the OH Valley Monday morning with more widely spaced convection trailing west-southwest into the Mid South/Ozarks. Considerable cloud cover with northward extent over a large moist/warm sector will limit destabilization into portions of PA and north. Farther south, heating of a very moist boundary layer will yield a moderate to very unstable airmass (1500 to 3000+ J/kg MLCAPE) from PA southward into the southern Appalachians. Multiple bands and clusters will likely begin to develop towards midday over the upper OH Valley and central Appalachians. Less certain is convective timing over the TN Valley where a large spread of model solutions is currently depicted. Nonetheless, scattered thunderstorms will likely develop by early to mid afternoon and become quite extensive from northern AL/GA into PA/VA/WV/MD. A mix of semi-discrete cells and clusters are possible initially and a risk for all severe hazards is expected given favorable shear profiles for storm organization/low-level rotation. Upscale growth is expected as storms move into the northern VA/MD and Chesapeake Bay vicinity during the late afternoon/early evening where the wind risk will seemingly be maximized. Much of the activity will eventually move east of the Mid-Atlantic coast during the evening and areas farther south through the Carolina Piedmont and into the coastal plain. Fun sounding disco for this region.
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