yoda

@Kmlwx @Eskimo Joe @high risk this sounds great for now lol (from the afternoon AFD from LWX) As we move toward the end of the week, a deep upper low and attendant strong surface low will slowly track eastward into the Upper Great Lakes. As this occurs, rich low-level moisture will be drawn north and east from the Gulf into the Ohio Valley and Mid- Atlantic. Simultaneously, a strong belt of mid-level flow (35-50 knots in the 700-500 hPa layer) will spread overtop that rich low- level moisture, advecting a remnant elevated mixed layer plume eastward as it does so. Rich low-level moisture, steeper than climatology mid-level lapse rates, and strong mid-level flow will result in an environment on Friday, and potentially even Saturday as well, characterized by both strong instability and strong deep layer shear. The EPS and GEPS ensemble means have 2000-3000 J/kg CAPE along with 35-50 knots of 0-6 km bulk shear. The GEFS show lesser instability and similar shear values, but have a well-know low bias when it comes to instability. This type of parameter space raises concerns for severe thunderstorms. While the parameter space being advertised at the moment by models is toward the higher end of what we typically see in this part of the country, we`re still at day 6 and 7, and there is plenty of time for things to change, especially when an upper level low is involved (which models notoriously struggle with in the long range). With an elevated mixed layer involved, there are also signs of stronger capping than we typically see, so that could complicate things as well. For now, the end of the week is a period to monitor for potential severe thunderstorms, with the expectation that the forecast can and will change this far out.

FFWs likely coming tomorrow SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... Monday will act as a day of transition ahead of a wet pattern setting up through around mid-week. The mentioned upper low swirling across the Deep South is part of a larger scale blocking regime (Rex Block). As a deep upper trough swings into the western U.S., this will help nudge the stalled downstream upper low. As this feature gains latitude in time, so will its immense moisture pool, strong jet forcing, and overall shift in sensible weather. Its slow poleward movement will carry some risk of flooding, particularly where upslope trajectories come into play (i.e., the eastern slopes of the Blue Ridge Mountains). Although the local area is in continued drought conditions, forecast rainfall amounts are high enough to cause some flooding concerns late Monday through at least Tuesday night. The latest forecast package calls for rain to arrive into the Potomac Highlands and central Shenandoah Valley by Monday morning. Amounts should initially be light, particularly in light of initial dry boundary layer conditions which may cause some evaporation to occur. However, eventual moistening of the column is expected which will gradually increase overall precipitation efficiency. The swath of showers is expected to track northeastward in time before reaching the I-95 metros by around the evening rush hour. Despite all of the increased cloud cover, high temperatures should still reach the low/mid 70s, with 60s more likely across the central Shenandoah Valley back into the Alleghenies. Conditions continue to deterioriate into the night with southeasterly moist advection further increasing. This moisture plume appears tied all the way down through the southern Gulf of America into the western Caribbean. Characterized by precipitable waters around 1.50 to 1.60 inches, this is easily 1.5 to 2 standard deviations above average for mid-May. Not surprisingly, forecast rainfall amounts are quite high, but are also variable due to uncertainies in the upper low track. By Tuesday morning, the main upper low is expected to lift across the Mid-South toward the southern Appalachians. The surface reflection of this system weakens as the upper low slowly begins to fill, but the quality of moisture remains intact. Tuesday will offer plenty of rainfall with 6-hour totals in the 0.25 to 0.50 inch range, locally higher toward the Blue Ridge. Given how spread out this event occurs over, much of this rain could prove to be beneficial in nature. However, this will less likely be the case along and east of the Blue Ridge where storm totals could be double the rest of the area. Current forecast storm totals are around 1.50 to 2.00 inches, but with 2.50 to 4.00 inches in the mentioned mountainous locations. While Flood Watches are not out yet, these will likely be considered during subsequent shifts.

Next Friday into the weekend looks intriguing per afternoon AFD from LWX After a short reprieve, the system later in the week will have a lot more fuel to work with. As high temperatures on Friday are expected to rise into the mid/upper 80s (coupled with dew points approaching 70 degrees), instability should be plentiful. Some strong to severe thunderstorms are possible as this system tracks through on Friday into early next weekend. Details hopefully become more apparent in the next few days.

Afternoon AFD from LWX makes it sound good The upper low will continue to slowly drift northeastward from the Lower Mississippi Valley into the Tennessee Valley Monday into Monday night. As this occurs, showers will gradually overspread the area from southwest to northeast. As it stands now, most guidance holds precipitation off in the DC Metro until the late afternoon or early evening hours, with precipitation not starting until after dark Monday night around Baltimore. The rain may start to become steadier and moderate to locally heavy at times by late Monday night, especially across Central Virginia. By Monday night, model soundings show deep, saturated profiles, with very limited instability and precipitable water values closing in on 1.5 inches. The lack of instability should limit rainfall rates somewhat, with most of the rain falling as a steady, soaking rain as opposed to very heavy downpours that you`d typically see with a summer thunderstorm. Still, model guidance hints that rainfall totals may reach around 1-2 inches across Central Virginia by daybreak Tuesday, with more rain expected to fall Tuesday into at least Wednesday (see long term discussion below). && .LONG TERM /TUESDAY THROUGH SATURDAY/... A highly amplified and blocky synoptic pattern sets up for a majority of next week. The initial feature of interest is a slow moving closed low which is currently spinning over the Deep South. This deep and anomalous system is set to become more negatively- tilted in time while crossing the Tennessee Valley on Tuesday. Eventually this trough begins to evolve into more of an open wave as it treks toward the Mid-Atlantic region by mid-week. The slow forward motion of this particular system may not see the trough axis pass by until Thursday morning. At this point, the associated surface fronts exit into the coastal Atlantic as high pressure briefly returns. Mid/upper heights begin to build in earnest by late in the work week ahead of the next weather maker. What is currently a strong upper trough off the West Coast will undergo a complex evolution across the nation over the next several days. As expected, a large array of spread is noted across the board when evaluating all recent guidance. The overall pattern shift does favor unsettled conditions on Friday into portions of next weekend. Looking more closely at Tuesday into Wednesday, the mentioned closed low will tap into anomalous Gulf moisture. Characterized by anomalies around 1 to 1.5 standard deviations above normal, this system will interact with strong dynamics with the upper low to produce periods of moderate to heavy rainfall. Ensembles support around 2 to 3 inches of rain during a 24 to 48 hour period. Depending on how much of this falls at once, there will be some flood threat that emerges. However, this will depend on location and intensity of such showers.

Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0400 AM CDT Sat May 10 2025 Valid 131200Z - 181200Z ...DISCUSSION... Medium-range guidance indicates that a generally amplified, split mid/upper flow will persist across the mid-latitude Pacific through North America next week. It appears that this will include at least a couple of significant troughs digging inland of the U.S. Pacific Coast. The first may already be in the process of developing eastward across the Intermountain West early in this period (Tuesday), before progressing across the Rockies, Great Plains and Mississippi Valley during the middle through latter portion of next week. This may be followed by another significant trough digging inland of the Pacific coast by early next weekend. The lead trough will be relatively close on the heels of the remnants of an initially broad quasi-stationary/cut-off low, which may only slowly progress east of the Mississippi Valley through Atlantic Seaboard during the early to middle portion of next week. Low-level moisture return, in the wake of this perturbation and ahead of the mid-level trough emerging from the West, may continue to be impacted across at least parts of the Great Plains into mid week. Thereafter, there appears a general consensus that there will be a better coupling of large-scale forcing for ascent, aided by surface cyclogenesis, with a notable increase in low-level moisture and destabilization across the lower Missouri Valley into the Upper Midwest and lower Ohio Valley by late next Thursday into Thursday night. In the presence of strong shear, it appears that this environment could become supportive of supercells and/or one or two organizing severe storm clusters. Machine learning output and other guidance suggests that potential for strong to severe thunderstorms could persist and potentially become more widespread across the Ohio Valley into Mid Atlantic, and southern Great Plains, next Friday and Saturday. However, uncertainties remain too large at this time to introduce greater than 15 percent severe probabilities. ..Kerr.. 05/10/2025

Morning AFD from LWX suggests we all take .LONG TERM /TUESDAY THROUGH FRIDAY/... Main feature through the long term will be an ULL tracking from the Lower Mississippi Valley into the Mid-Atlantic before shearing out late in the week. Rain chances increase notably Tuesday into Wednesday as the ULL moves nearby. Unlike the past several ULLs to impact the area, this one originating from the Gulf will bring much more moisture with it. However, considerable uncertainty remains with QPF amounts among ensemble guidance, though a notable uptick from 24 hours ago. The probabilities of 1" of QPF is now in the 50- 70% range for much of the CWA. Given the spread, 2" probs are generally low, with the exception of the eastern slopes of the Blue Ridge where ensemble guidance highlights generally 30-40% probabilities. It should be noted some members do have several inches of rain across the FA, which could result in flooding if that came to fruition. The Weather Prediction Center has introduced a Slight Risk for excessive rainfall for portions of the area Tuesday/Tuesday night. Hopefully more clarity over the next several forecast cycles.

WPC has our area outlooked on Days 3 and 4 for excessive rainfall https://www.wpc.ncep.noaa.gov/qpf/excessive_rainfall_outlook_ero.php

@WxWatcher007 would not be pleased https://x.com/AndyHazelton/status/1920133584146354231

Just got warned BULLETIN - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Warning National Weather Service Baltimore MD/Washington DC 617 PM EDT Mon May 5 2025 The National Weather Service in Sterling Virginia has issued a * Severe Thunderstorm Warning for... Northwestern Stafford County in northern Virginia... Southeastern Fauquier County in northern Virginia... Southern Prince William County in northern Virginia... * Until 645 PM EDT. * At 616 PM EDT, a severe thunderstorm was located 7 miles west of Stafford, moving north at 15 mph. HAZARD...Quarter size hail. SOURCE...A trained weather spotter observed quarter size hail in Glendie. IMPACT...Some hail damage to agriculture is expected. * Locations impacted include... Heflin, Ruby, Somerville, and Roseville. PRECAUTIONARY/PREPAREDNESS ACTIONS... For your protection move to an interior room on the lowest floor of a building. && LAT...LON 3841 7748 3840 7756 3854 7767 3858 7751 TIME...MOT...LOC 2216Z 158DEG 15KT 3842 7754 HAIL THREAT...OBSERVED MAX HAIL SIZE...1.00 IN WIND THREAT...RADAR INDICATED MAX WIND GUST...<50 MPH

You will take your watch and like it good sir

40/20 on both hail and wind probs... 20 on 2 or more tornadoes probs

Watch up until midnight

Watch up until midnight URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 228 NWS Storm Prediction Center Norman OK 600 PM EDT Mon May 5 2025 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of District Of Columbia Maryland Southern Pennsylvania Northern and Eastern Virginia Eastern Panhandle West Virginia Coastal Waters * Effective this Monday night from 600 PM until Midnight EDT. * Primary threats include... Scattered damaging wind gusts to 70 mph possible Scattered large hail events to 1.5 inches in diameter possible A tornado or two possible SUMMARY...Scattered linear clusters of strong to severe thunderstorms will likely develop and move northward into the Watch area this evening. A few of the stronger cellular storms will pose a risk for large hail (1 to 1.5 inches in diameter). A transient supercell or two is possible in addition to a couple of line segments. Strong to severe gusts capable of wind damage will be the primary hazard with these storms, but a brief tornado is possible mainly early this evening with this activity. The severe thunderstorm watch area is approximately along and 60 statute miles east and west of a line from 35 miles east northeast of Hagerstown MD to 25 miles southwest of Patuxent River MD. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU8).

Watch potentially coming soon Mesoscale Discussion 0701 NWS Storm Prediction Center Norman OK 0429 PM CDT Mon May 05 2025 Areas affected...Parts of the Mid-Atlantic Concerning...Severe potential...Watch possible Valid 052129Z - 052330Z Probability of Watch Issuance...60 percent SUMMARY...Thunderstorms moving north out of southeast Virginia will migrate into a buoyant air mass in place across the DelMarVa region. Re-intensification is expected and may result in an uptick in the severe hail/wind threat. Watch issuance is being considered to address this potential. DISCUSSION...A mix of semi-discrete thunderstorms and weakly organized linear segments continues to migrate north out of southeast VA. While a few stronger cores persist, much of the convection currently appears weak/disorganized based on GOES IR imagery and MRMS vertical ice/echo top data. However, these storms are moving into an environment characterized by better buoyancy (MLCAPE between 1000-2000 J/kg) that is in place across the DelMarVa region. Consequently, some uptick in intensity is anticipated within the next 1-2 hours. Deep-layer wind shear sampled by regional VWPs is fairly modest - around 20-25 knots of 0-6 km BWD. However, this should be sufficient for a few organized cells and linear segments capable of producing damaging winds and 1.0 to 1.5 inch hail. ..Moore/Smith.. 05/05/2025 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...PHI...AKQ...CTP...LWX... LAT...LON 37687760 38617858 39057882 39307881 39677865 39997827 40077798 40057760 39837722 39257636 38867603 38407592 38117592 37777606 37557624 37357656 37357685 37467726 37687760 MOST PROBABLE PEAK TORNADO INTENSITY...UP TO 95 MPH MOST PROBABLE PEAK WIND GUST...55-70 MPH MOST PROBABLE PEAK HAIL SIZE...1.00-1.75 IN