####018008629#### FXUS62 KRAH 031836 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 236 PM EDT Fri May 3 2024 .SYNOPSIS... Sub-tropical high pressure will extend across the South Atlantic states today, while a backdoor cold front will move through eastern VA and northeastern NC. The front will settle southwestward and into north-central NC tonight, where it will stall through Saturday night, then weaken and move northward into VA on Sunday. && .NEAR TERM /THROUGH TONIGHT/... As of 1145 AM Friday... A mid/upr-level ridge centered near the srn Middle Atlantic coast will remain so through tonight, while a mid-level trough and embedded, weak MCVs now over the ern OH and TN Valleys will be directed around the ridge and into the cntl Appalachians. At the surface, a 1019-1020 mb sub-tropical high will remain situated off the coast of the Carolinas. Meanwhile, a backdoor cold front, now stretching from the mouth of the Chesapeake Bay nwwd to a 1014 mb frontal low over OH, will merge with a developing bay breeze and move swwd to the vicinity of the Roanoke River between 22Z-00Z. A separate, srn stream front extending from cntl TX enewd and across the lwr MS and TN Valleys, to a 1013 mb frontal low over Middle/wrn TN, then ewd across nrn GA and the Piedmont of the Carolinas, will move little through the period. With no airmass change from Thu and continued influence of ridging aloft, today will be persistently, unseasonably warm, with temperatures continuing at 10-15F above average - mid 80s to around 90. Showers and isolated storm will focus today along both fronts noted above, including into the NC nrn Coastal Plain and far ne Piedmont early this evening and also with diurnal heating along a differential heating zone evident in late morning visible satellite and surface observational data along the srn stream front from AGS to HKY. The latter activity, should it indeed develop, would then be steered in weak wswly steering flow and into the srn and wrn NC Piedmont late this afternoon-evening. Areas of persistence fog and low stratus will likely redevelop into the srn-cntl Coastal Plain and ern Sandhills tonight, while a separate area of post-frontal, very low stratus will develop behind the backdoor front across the ne Piedmont and nrn Coastal Plain. Temperatures tonight will remain unseasonably mild and mostly persistent in the upr 50s to mid 60s. && .SHORT TERM /SATURDAY AND SATURDAY NIGHT/... As of 225 AM Friday... Confidence is high on increasing chances for showers and a few storms, although no one will see rain the entire day, and pinpointing the location and motion of what should be shower/storm clusters is challenging. PWs will continue to rise, with models indicating a swath of 1.5-1.75" values surging up through central NC, in the 90th percentile and even nearing daily records. This will occur in tandem with increasing low level moisture flux drawing Atlantic moisture into our area. As the backdoor front settles further into the area Sat morning, followed by a very gradual weakening and washing out, the considerable stratus over much of the area, esp N and W sections, will hinder heating and destabilization until it retreats and breaks up later in the day. And our large scale dynamic forcing for ascent will be poor, given the weak mid- upper level flow, but we may still feel the effects of MCVs emanating from today's Plains convection as it shifts into our area late Sat through Sat night. All of this supports scattered to numerous clusters of showers and storms, particularly in areas W of I-95 where moisture will be deepest, with the highest pops in the Triad and perhaps a secondary focus along the weakening backdoor frontal zone. The storm threat will be limited, given the weak deep layer bulk shear and modest CAPE, but a few storms will remain possible mainly in the afternoon and evening. Rain chances will persist overnight with further moistening of the low levels with confluent 925 mb southerly flow strengthening to 15-25 kts with both Atlantic and Gulf taps. While areally averaged rainfall amounts aren't likely to be high, given the anomalously high PW and somewhat slow storm motion with cell mergers possible, isolated areas could see local rainfall totals that could present minor urban flooding issues, esp in the Triad region, despite the recent dry weather. With mostly cloudy to cloudy skies, expect highs from the mid 70s N and W to lower-mid 80s SE. Lows in the 60s. -GIH && .LONG TERM /SUNDAY THROUGH THURSDAY... As of 250 AM Friday... ...Elevated Rain Chances Will Linger Through Monday... ...Heat Returns Middle Part of Next Week... Sunday and Sunday night: The stalled sfc front sagging across northern portions of the forecast will retreat north early Sunday, leaving all of central NC in the warm sector. Subtle upper disturbances coupled with the development of weak to moderate buoyancy during the afternoon will act upon the elevated PWATS (150- 160% of normal)in place over the region to support afternoon showers and storms. Shear is generally less than 20 kts, so the threat for organized severe storms is near zero. The moist PWATs and associated mostly cloudy skies and rain chances should temper afternoon temps. Highs in the upper 70s north to lower 80s. Convection should largely dissipate as BL nocturnally cools and stabilizes. Under mostly cloudy skies, mild overnight temps in the 60s. Monday and Monday night: A compact shortwave trough over the Mid MS Valley will become increasingly sheared as it crosses the central and southern Appalachians Monday afternoon and through the Mid Atlantic States Monday night. PWATs are forecast to increase to ~200% of normal as the trough and associated DPVA moves through the area. As such, expect another healthy uptick in diurnal coverage and PoPs Monday afternoon and into the evening. Shear remains weak. Thus, the threat for severe storms remains low. Low-level thicknesses are on par or slightly higher than Sunday. Highs 80-85. Lows in the 60s. Tuesday through Thursday: Rain chances will lessen during this period, with weak disturbances moving atop the ridge providing the primary focus for scattered shower and storms, mainly across northern portion of the forecast area. The main weather headlines will be the return of the heat during the second half of the work week. Highs Wednesday and Thursday are expected to top out in the mid/upper 80s north lower 90s over interior and southern portions of the forecast area. Expect very warm nights as well, potentially record warm, with lows 65 to 70. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... As of 235 PM Friday... Isolated to widely scattered showers and storms will focus this afternoon-evening along a differential heating zone and surface trough over the Foothills and wrn Piedmont of NC (including at INT/GSO) and also along a backdoor cold front that will reach the Roanoke River vicinity (including near and just north of RWI) around sunset. Areas of very low overcast and fog will likely redevelop through sern NC, including to around FAY between 10-12Z, in a persistence regime of humid, sly flow there. Meanwhile, a separate area of post-frontal, low stratus in enely flow, will develop behind the backdoor front and reach RWI and all Piedmont sites around the same time (between 10-12Z). Ceilings in both regimes should then lift through MVFR through midday Sat, during which time showers/ storms are apt to redevelop with diurnal heating. The greatest concentration of that convection should be along the front, which will likely become quasi-stationary between I-85 and US-64 on Sat. Outlook: IFR-MVFR ceilings are likely to redevelop each night- morning through Monday, as are scattered to locally numerous showers/storms each afternoon-evening. && .CLIMATE... Record High Temperatures: May 3: KGSO: 92/1959 KRDU: 93/1959 KFAY: 95/1913 Record High Minimum Temperatures: May 4: KGSO: 65/2022 KRDU: 68/1938 KFAY: 68/1942 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...Hartfield LONG TERM...CBL AVIATION...MWS ####018008851#### FXUS62 KRAH 031838 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 238 PM EDT Fri May 3 2024 .SYNOPSIS... Sub-tropical high pressure will extend across the South Atlantic states today, while a backdoor cold front will move through eastern VA and northeastern NC. The front will settle southwestward and into north-central NC tonight, where it will stall through Saturday night, then weaken and move northward into VA on Sunday. && .NEAR TERM /THROUGH TONIGHT/... As of 1145 AM Friday... A mid/upr-level ridge centered near the srn Middle Atlantic coast will remain so through tonight, while a mid-level trough and embedded, weak MCVs now over the ern OH and TN Valleys will be directed around the ridge and into the cntl Appalachians. At the surface, a 1019-1020 mb sub-tropical high will remain situated off the coast of the Carolinas. Meanwhile, a backdoor cold front, now stretching from the mouth of the Chesapeake Bay nwwd to a 1014 mb frontal low over OH, will merge with a developing bay breeze and move swwd to the vicinity of the Roanoke River between 22Z-00Z. A separate, srn stream front extending from cntl TX enewd and across the lwr MS and TN Valleys, to a 1013 mb frontal low over Middle/wrn TN, then ewd across nrn GA and the Piedmont of the Carolinas, will move little through the period. With no airmass change from Thu and continued influence of ridging aloft, today will be persistently, unseasonably warm, with temperatures continuing at 10-15F above average - mid 80s to around 90. Showers and isolated storm will focus today along both fronts noted above, including into the NC nrn Coastal Plain and far ne Piedmont early this evening and also with diurnal heating along a differential heating zone evident in late morning visible satellite and surface observational data along the srn stream front from AGS to HKY. The latter activity, should it indeed develop, would then be steered in weak wswly steering flow and into the srn and wrn NC Piedmont late this afternoon-evening. Areas of persistence fog and low stratus will likely redevelop into the srn-cntl Coastal Plain and ern Sandhills tonight, while a separate area of post-frontal, very low stratus will develop behind the backdoor front across the ne Piedmont and nrn Coastal Plain. Temperatures tonight will remain unseasonably mild and mostly persistent in the upr 50s to mid 60s. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... As of 230 PM Friday... Aloft, the sub-tropical ridge will stall along the eastern seaboard through Sat night. A southern stream disturbance will move into the Southeast US on Sat, then lift newd through the area as a sheared out northern stream s/w moves through the OH Valley/Great Lakes Sat night. The sub-tropical ridge will shift offshore and breakdown Sun/Sun night as the disturbances move through the mid-Atlantic and Northeast US. Another southern stream s/w will develop over the southern Plains on Sun, then move eastward into the lower/mid-MS Valley Sun night. At the surface, as high pressure sits over the New England coast, the backdoor cold front is expected to stall over nrn/nern NC through Sat and into Sat night then lift northward late Sat night/Sun. The high should move eastward over the Atlantic as a low moves through the Great Lakes and into the Northeast Sun/Sun night. Precipitation/Convection: Still fairly high confidence/chances for showers and possible storms Sat and Sun. Best threat for storms will be across the Piedmont, mainly along and south of the surface boundary, where surface-based CAPE will be maximized. Bulk shear still appears weak, and PWATs are expected to range from 1.4 to 1.8 inches. Do not expect the entire day to be a wash-out by any means, and Sat could start dry for most, but there will be a chance for showers across all of central NC, with greatest coverage from Sat eve through Sun aft. Highest chances NW, lowest SE. Given the high PWATs and scattered, somewhat disorganized mode of convection, isolated locations could receive locally heavy rainfall, with any potential for minor flooding issues largely limited to urban areas. Temperatures: A bit tricky on Sat, as there is some bust potential north of the front. Widespread overcast skies should somewhat limit heating as well. For now expect highs to range from the mid 70s along the NC/VA border to mid 80s SE. Sat night temps should be continued mild, mainly in the low to mid 60s. On Sun, with the retreat of the front northward, areas across the north may be a few degrees higher than Sat, but given the expected showers/storms through the day, temps may otherwise be limited. Highs in the upper 70s north to low 80s south. && .LONG TERM /SUNDAY THROUGH THURSDAY... As of 250 AM Friday... ...Elevated Rain Chances Will Linger Through Monday... ...Heat Returns Middle Part of Next Week... Sunday and Sunday night: The stalled sfc front sagging across northern portions of the forecast will retreat north early Sunday, leaving all of central NC in the warm sector. Subtle upper disturbances coupled with the development of weak to moderate buoyancy during the afternoon will act upon the elevated PWATS (150- 160% of normal)in place over the region to support afternoon showers and storms. Shear is generally less than 20 kts, so the threat for organized severe storms is near zero. The moist PWATs and associated mostly cloudy skies and rain chances should temper afternoon temps. Highs in the upper 70s north to lower 80s. Convection should largely dissipate as BL nocturnally cools and stabilizes. Under mostly cloudy skies, mild overnight temps in the 60s. Monday and Monday night: A compact shortwave trough over the Mid MS Valley will become increasingly sheared as it crosses the central and southern Appalachians Monday afternoon and through the Mid Atlantic States Monday night. PWATs are forecast to increase to ~200% of normal as the trough and associated DPVA moves through the area. As such, expect another healthy uptick in diurnal coverage and PoPs Monday afternoon and into the evening. Shear remains weak. Thus, the threat for severe storms remains low. Low-level thicknesses are on par or slightly higher than Sunday. Highs 80-85. Lows in the 60s. Tuesday through Thursday: Rain chances will lessen during this period, with weak disturbances moving atop the ridge providing the primary focus for scattered shower and storms, mainly across northern portion of the forecast area. The main weather headlines will be the return of the heat during the second half of the work week. Highs Wednesday and Thursday are expected to top out in the mid/upper 80s north lower 90s over interior and southern portions of the forecast area. Expect very warm nights as well, potentially record warm, with lows 65 to 70. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... As of 235 PM Friday... Isolated to widely scattered showers and storms will focus this afternoon-evening along a differential heating zone and surface trough over the Foothills and wrn Piedmont of NC (including at INT/GSO) and also along a backdoor cold front that will reach the Roanoke River vicinity (including near and just north of RWI) around sunset. Areas of very low overcast and fog will likely redevelop through sern NC, including to around FAY between 10-12Z, in a persistence regime of humid, sly flow there. Meanwhile, a separate area of post-frontal, low stratus in enely flow, will develop behind the backdoor front and reach RWI and all Piedmont sites around the same time (between 10-12Z). Ceilings in both regimes should then lift through MVFR through midday Sat, during which time showers/ storms are apt to redevelop with diurnal heating. The greatest concentration of that convection should be along the front, which will likely become quasi-stationary between I-85 and US-64 on Sat. Outlook: IFR-MVFR ceilings are likely to redevelop each night- morning through Monday, as are scattered to locally numerous showers/storms each afternoon-evening. && .CLIMATE... Record High Temperatures: May 3: KGSO: 92/1959 KRDU: 93/1959 KFAY: 95/1913 Record High Minimum Temperatures: May 4: KGSO: 65/2022 KRDU: 68/1938 KFAY: 68/1942 && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...MWS NEAR TERM...MWS SHORT TERM...KC LONG TERM...CBL AVIATION...MWS ####018007993#### FXUS61 KPHI 031839 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 239 PM EDT Fri May 3 2024 .SYNOPSIS... High pressure builds into New England with onshore flow setting up. A series of cold fronts approaches for the weekend, with the second (and stronger of the two) front stalling out nearby by early next week. The stalled front lifts north as a warm front at some point in the Tuesday/Wednesday timeframe, bringing a return to above normal temperatures. && .NEAR TERM /THROUGH SATURDAY/... 235 PM...It's a challenging near term forecast due to different competing forces. On the one hand, an expansive ridge of high pressure is building into eastern Canada with the southwestward periphery of this feature extending back into the mid Atlantic. And in fact guidance actually depicts this feature strengthening slightly over our area during the next 24 hours. Meanwhile though, this ridge has resulted in easterly flow that has brought in a low deck of some marine stratus into much of NJ, DE, and even extending at times into portions of eastern PA. Finally, there is a frontal system that's approaching from the west with some showers however it will take some time for these showers to get into the area over the weekend as it runs up against the ridge in place. The upshot of all this is that skies are variable across the area this afternoon with the marine stratus starting to mix out and retreat back to the east just within the past hour or two while at the same time some high cirrus has been moving in from the west. It's also a much cooler day compared to yesterday with temperatures as of 2 PM only in the 50s and 60s. As we go through the rest of this afternoon into the evening expect that we'll continue to see variable skies with low stratus continuing to be most persistent near the coast while western parts of the CWA over eastern PA continue to see some filtered sunshine through the high clouds. It will remain precip free though through the evening. Overnight, however, shortwave energy will ride over the top of the upper level ridge centered over the east and help to push showers from the west closer to the region. This could bring a few light showers into parts of Delmarva and eastern PA by daybreak. Otherwise, clouds thicken through the night with lows getting down mainly into the upper 40s to around 50. For Saturday, low pressure moves eastward towards the Great Lakes driven by an advancing upper level trough. As this occurs, showers well ahead of it will continuing to try making inroads into our area while running up against the stubborn surface high that will be slow to move out. The upshot is some scattered showers will likely make it in at times, especially over eastern PA and Delmarva and especially getting into the second half of the day (POPs here by late day generally 40 to 60 percent). Otherwise it will be a mostly cloudy and cool day with continuing easterly winds and highs only making it to the upper 50s to low 60s. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... Not the best weekend ahead weather-wise but not necessarily terrible either. A weakening cold front will approach on Saturday, with some showers moving through ahead of it. Best chance to see showers will be west of the I-95 corridor, but can't rule out some light rain across the area. Otherwise, it will be cloudy and cool with a steady onshore flow. Temperatures will be in the upper 50s/low 60s. With the maritime airmass in place, not expecting much in terms of thunderstorms as it should remain rather stable. Showers become more widespread by Saturday Night through Sunday Night as a stronger cold front approaches from the west. Highest PoPs are concentrated in the Sunday morning timeframe. Some elevated instability could move in for Sunday afternoon/evening but not expecting any severe weather, and just some rumbles of thunder mixed in with passing showers. The maritime airmass will continue to have a grip on the region, though flow turns a bit more southerly in southern Delmarva. The result will be another day in the upper 50s/low 60s for most, with upper 60s/70s in southern Delaware and along the southern Eastern Shore. && .LONG TERM /MONDAY THROUGH FRIDAY/... Unsettled conditions are expected for most of next week as a boundary stalls out over the region. Rain chances are in the forecast each day during the week as several waves of low pressure are expected to ride along the boundary. Each day won't be a washout by any means, and PoPs are generally around 20-40% Monday/Tuesday, with the highest coming in the afternoon. Not much instability will be present, with the threat of any thunderstorms/severe weather being low. Temperatures both days will be in the mid to upper 70s, with some 80s possible on Tuesday. The boundary looks to lift north by Tuesday in the form of a warm front, putting the region in the warm sector. Looking at a period of above normal temperatures for Wednesday/Thursday with upper 70s/low to mid 80s anticipated. A few shortwaves will move through, which will spark off some showers and thunderstorms, mainly in the afternoon/evening both days. More instability will be present, so we will have to watch this window, though too early to tell if/how impactful any convection will be. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Through this afternoon...Mainly MVFR predominating at ACY, MIV, TTN, and PNE due to low stratus. Otherwise mainly VFR with a scattered deck around 2500 feet. East winds 10 to 15 knots with some gusts to around 20 knots possible. Moderate confidence. Tonight...The marine stratus should result in MVFR cigs or lower eventually predominating by the overnight period with conditions lowering through the evening around PHL but likely not until the overnight at RDG and ABE. IFR cigs likely overnight at MIV and ACY. East winds 5 to 10 kt. Low confidence. Saturday...Mainly MVFR in the morning with some improvement in the afternoon to VFR except at MIV and ACY where MVFR may continue. East winds around 10 knots. Low confidence. Outlook... Saturday Night...Restrictions expected with steady rain moving through, with CIGs as low as IFR possible. Sunday...Restrictions expected with showers/low clouds moving through. CIGs as low as IFR possible. Sunday Night...Restrictions possible with 40-60% chance of showers and 15-25% chance of thunderstorms. Monday through Tuesday...Primarily VFR though some restrictions possible with any showers. 20-40% chance of showers through this period. && .MARINE... A Small Craft Advisory continues through this afternoon over our ocean zones as seas remain around 5 to 6 feet with winds gusting 20 to 25 knots. These conditions should diminish early this evening with seas diminishing to 10 to 15 knots and seas around 3 to 4 feet. Little change is expected on Saturday. It will also be mainly cloudy over the waters through Saturday with some patchy fog possible at times. Outlook... Saturday night through Tuesday...No marine headlines anticipated. Showers/thunderstorms possible on the waters Sunday through Sunday night. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Small Craft Advisory until 6 PM EDT this evening for ANZ450>455. && $$ SYNOPSIS...Hoeflich NEAR TERM...Fitzsimmons/MPS SHORT TERM...Hoeflich LONG TERM...Hoeflich AVIATION...Fitzsimmons/Hoeflich/MPS MARINE...Fitzsimmons/Hoeflich/MPS