Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/19/22


Area Forecast Discussion
National Weather Service Boston/Norton MA
1022 PM EDT Fri Mar 18 2022 .SYNOPSIS... Unsettled weather expected this weekend and not as mild. Widespread showers move through Saturday into Saturday evening, with a few rumbles of thunder possible. A few isolated showers possible across the interior on Sunday, but dry and blustery for most with seasonable temperatures. Breezy with seasonable temperatures Monday and Tuesday. Next shot for more widespread precipitation late on Wednesday into Thursday. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... No major changes to the overall forecast overnight. Main concern remains fog potential late tonight, which is still expected as high dew point air moves north over the relatively cooler ocean. The presence of a stalled front complicates things. Areas along the south coast of New England are most likely to get into the more widespread fog. Will be monitoring for a possible Dense Fog Advisory overnight. Otherwise, still expecting a risk for showers to develop after midnight across the western half of southern New England. 645 PM Update... No changes in the latest update. Main concern overnight is the redevelopment of stratus/fog. Still think that the locally dense fog will be most likely along the coast. Given we`ve had fog that past two evenings, am highly confident on it developing again tonight. Just uncertain on the exact timing, but think the HRRRE and other short term guidance has a decent handle on it. Due to the timing uncertainty have not hoisted a Dense Fog Advisory, but will probably be necessary for future updates. Discussion from 4 PM... Main issue tonight will be the redevelopment of stratus and fog which may be locally dense, especially near the coast. The fog bank is already lurking over Nantucket sound. Higher dewpoint air several degrees higher than water temps with onshore flow turning SE later tonight will result in stratus and fog expanding along the coast this evening and eventually into the interior overnight. Areas of dense fog are possible and dense fog advisories may eventually be needed. Otherwise, lead shortwave ahead of mid level trough to the west will lift across New York into northern New Eng overnight. While, best chance of showers will be to the north and west, a few showers are expected to move into western New Eng late tonight as low level jet approaches from the west. Weak backdoor front from northern New Eng drops south and likely stalls across northern MA tonight with wind shift to NE. S/SE winds will persist closer to the coast. Temps will fall back into the 40s overnight. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Saturday... Modest low level jet and increasing PWAT plume 1 to 1.25" moves into SNE with accompanying area of showers lifting NE across the region. There is some elevated instability developing in the afternoon so can`t rule out an isolated t-storm with any of the heavier showers. The CAMs indicate that there may be a lull in the activity in western New Eng mid/late afternoon as the focus shifts to the east. Temps will be mildest south of the Pike and especially across CT/RI and SE MA which will be south of the boundary with southerly winds. In fact, winds may gust to 20-30 mph near the south coast and Cape/Islands during the afternoon as the low level jet develops. Highs should reach well into the 50s to near 60 here. Cooler temps in northern MA where northerly winds should keep highs closer to 50 near the NH/VT border. Saturday night... Fairly robust shortwave from western NY lifts NE into northern NY/VT in the evening with cold front approaching from the west. Expect a weakening line of convection approaching western MA/CT in the evening as activity becomes further removed from best forcing lifting well to the NW. But will have to monitor these storms as they move in from the west. Further weakening is expected as the showers move east across SNE through midnight. Meanwhile, elevated instability peaks in the evening across the Cape/Islands within the axis of a 50-60 kt low level jet. MUCAPES may approach 1000 J/kg so will have to watch any convection around the Cape Islands as deep layer shear is rather strong and is supportive of hail if elevated instability is realized. HRRR is most aggressive with storms moving across Cape/Islands in the 6-8 pm time frame. Drying conditions expected overnight behind the front as the column dries. However, areas of fog will likely persist over the Cape/Islands through the night. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Highlights: * Isolated showers possible across the interior on Sunday, but dry for most. Above normal temps across the region and breezy. * Dry with near to above normal temps persisting for much of Monday and Tuesday. Gusty winds persist. Cannot completely rule out an isolated shower or two along the south coast late on Monday into early Tuesday. * Next shot for widespread heavier precip possible late on Wednesday into Thursday. Could have some wintry precip with this, but still too early for exact details. Sunday... A trough will lift from the OH Valley/Carolinas early in the day into southern New England by the evening and offshore late on Sunday/early Monday. A ridge axis will build across the Mississippi River Valley. Low pressure will lift across Quebec/northern New England further northeastward, however will have a surface trough extend from the low into southern New England. Generally expecting dry and quiet weather for most, as high pressure nudges into the region and WNW/NW downslope flow aids in some drying out moisture in the lower levels. However, have kept slight chances of precip across portions of interior MA given the trough lifting in late in the afternoon. Have a pretty good cold pool associated with this as 500 hPa temps are in the -25 to -20 degree Celsius range. This in combination with diurnal heating and decent RH locked in the low/mid levels should result in isolated rain showers. Elsewhere think that there will be a good amount of CU given the cold pool moving in, but moisture will be a bit more limited further S/E. The only changes made were increasing the temps and wind speeds/gusts. As previously mentioned have some decent downslope flow with W/WNW flow at 925 hPa. Speeds up in the level are around 20-30 kts, which will not be too difficult to mix down given the boundary layer grows to roughly 3-5 kft. Manually bumped up the wind speeds/gusts a bit given what am seeing in the Bufkit soundings. Have increased the temps to the 75th percentile of guidance given the downslope flow. The only potential wrench is the amount of cloudiness that develops as the trough is lifting in. Think that the CT/Merrimack Valley could see some low/mid 60 degree readings. Elsewhere temps will be in the 50s. Monday through Tuesday... Ridge axis over the Mississippi River Valley builds into the OH Valley/central Great Lakes on Monday into Tuesday. More confident in the amplitude/progression of the ridge today. On the northeast side of the ridge a shortwave will dig into the eastern Great Lakes late Monday/early Tuesday. Throughout much of this period high pressure will build into the region from the Carolinas/Mid Atlantic and Ontario. The high over the Carolinas will move offshore late Monday/early Tuesday while the high over Ontario nudges in more on Tuesday as it builds into Quebec. Generally expecting dry and quiet weather throughout this period with high pressure in control. Did increase PoPs to slight chances across the south coast late on Monday into early Tuesday. A cold front swings through and appears that there is enough moisture for an isolated shower or two. May need to expand this slight chance further north in future updates if the GEPS/GEFS/EPS guidance continue to indicate there could be some light precip a bit further inland. Really not expecting any impacts other than breaking up a period of dry weather. Most confident on both days featuring near to above normal temps along with gusty winds. Will have prolonged WNW/NW flow with speeds of 20-40 kts in roughly the 850 and 925 hPa levels. Given the cooler air advecting in should see excellent mixing on both days. Do think that the gustier of the two days will be on Tuesday where there could be some 25-30 kt gusts during the afternoon. Still breezy on Monday, but think gusts falling mostly in the 20-25 kt range. Will have temps in the 50s across the region on Monday. Does cool a bit in wake of that frontal passage for Tuesday with highs in the upper 40s to low 50s. Wednesday and Thursday... Most uncertainty in the forecast lies during this period. Main change made in the latest update was the slow down the progression of precip chances on Wednesday from the NBM guidance as it seems too fast compared to other pieces of ensemble guidance. Have a blocky ridge/trough pattern in place with a ridge building from the central Great Lakes early on Wednesday into the eastern Great Lakes/New England by late in the day. Behind the ridge a cutoff/deep trough lifts northeastward later on Wednesday into Thursday as the ridge builds further northeast. As mentioned, lots of uncertainty through this timeframe. Did hedge toward the drier end of guidance for much of Wednesday given that the high over Quebec will still be nudging into southern New England as this system is deepening over the IA/MO/IL/WI area. Will take a bit for the drier air to moisten up, and the current PoPs match well with the timing of GEPS/GEFS/EPS 24 hr measurable QPF. Biggest uncertainty for late Wednesday is the position of the ridge and its amplitude based on WPC Cluster analysis. At this point 55/100 ensemble members keep us dry as the ridge is more built up. The wetter solutions feature a weaker ridge that is a bit further east along combined with a deeper trough or a more flattened out trough/ridge. The former (28 members) features heavier precip moving in quicker, whereas the latter would bring in lighter QPF. Again at this point have leaned on the drier guidance for Wednesday, so bumped PoPs back. May need to bring back further in future updates. Confidence increases in precip chances late on Wednesday through Thursday. Most uncertainty lies here in the amplitudes of the trough/ridge and then the position of the trough. All guidance shows QPF across the region during this window, but just a question of the exact details. The wetter solutions (60/100 members) essentially feature a deeper ridge/trough, whereas the drier solutions show a less amplified trough/ridge. Given it is a 60/40 spread and we are talking Day 7, have leaned on NBM as things can change. Confidence highest in at least some precip here, so have kept chance to likely precip late on Wednesday through much of Thursday. Do have some uncertainty in the exact track of the frontal system moving through, but thermal profiles suggest there will be some wintry precip. Still see some low probabilities of snowfall amounts AOA 1 inch across portions of the interior late on Wednesday into early Thursday per the EPS/GEFS/GEPS guidance. Given the track of the system thinking that any wintry precip should change over to rain as warmer air surges in, but there is considerable uncertainty in the thermal profiles. At this point will need to stay tuned until there is more confidence in how things will evolve. Lots of uncertainty in this timeframe with regard to timing, intensity and location of the next trough lifting into the region. Have stuck with the NBM guidance as models are all over the place at this point in time. Think that there will be precipitation somewhere in this window, but hard to pin point down. Have kept chances to likely PoPs per the NBM through the Wed-Fri timeframe. Majority of the variance on Thursday is due to the positioning on the ridge and the amplification of the trough/ridge per WPC cluster analysis (35 percent variance in the positioning of the ridge and 28 percent on the amplification). Late in the week the uncertainty falls mostly in the amplification/deamplification of the ridge/trough. Given the uncertainty have not hedged in any direction. Will note that there are some low probabilities of snowfall AOA 1 inch per the GEFS/GEPS guidance for late Wednesday into Thursday, while the EPS is a warmer solution with no snow probs AOA 1 inch. Again something to monitor, but still too early to hammer down the exact details. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Tonight...High confidence in trends. Moderate on exact timing. IFR to VLIFR stratus and fog expanding along the coast through 06Z. Will see the stratus/fog spread farther inland after 06Z. Expecting dense fog especially along the immediate coastline. Showers developing across western New Eng 09-12Z. Saturday and Saturday night...Moderate confidence. IFR to VLIFR conditions with areas of fog and widespread showers moving across the region during Sat into Sat evening, then exiting around midnight. Isolated t-storms possible. Have added a VCTS mention across the Cape/Islands where have a bit more confidence in the activity late in the afternoon. May need to be expanded elsewhere if confidence in coverage increases. Will improve to VFR late Sat night, but areas of IFR/LIFR persisting Cape/Islands until daybreak. S wind gusts 20-25 kt developing late Sat/Sat evening Cape/Islands along with areas of LLWS accompanying low level jet. KBOS TAF...High confidence in trends. Expect stratus and fog redeveloping tonight with a return to LIFR 04-06Z, but exact timing uncertain. Expect a period of VLIFR fog near the morning push. KBDL TAF...Moderate confidence. LIFR stratus and fog may redevelop after 06Z. Outlook /Sunday through Wednesday/... Sunday through Sunday Night: Mainly VFR, with local MVFR possible. Breezy. Monday: VFR. Breezy. Monday Night: VFR. Breezy. Isolated SHRA. Tuesday through Tuesday Night: VFR. Windy with local gusts up to 30 kt. Wednesday: VFR. Chance RA. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Tonight... Leftover southerly swell will keep seas near 5 ft over outer southern waters this evening before subsiding overnight. Variable winds below SCA. Poor vsbys as areas of dense fog develop. Saturday... Increasing S winds with gusts 25-30 kt developing in the afternoon as low level jet develops. Building seas. Poor vsbys in showers and fog. Isolated t-storms possible in the afternoon. Saturday night... Gusty S winds in the evening becoming SW and diminishing overnight. 5-8 ft seas over souther waters. Vsbys reduced in showers and fog and isolated t-storms in the evening. Outlook /Sunday through Wednesday/... Sunday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Sunday Night: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Monday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Monday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Isolated rain showers. Tuesday: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Local rough seas. Tuesday Night: Low risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of seas approaching 5 ft. Wednesday: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain. && .CLIMATE... Below are the record highs for Today, March 18th: BOS: 74F (2012) BDL: 76F - previously 72F (2012) PVD: 73F (2011) ORH: 74F (2012) && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 1 PM Saturday to 5 AM EDT Sunday for ANZ232. Small Craft Advisory from 1 PM Saturday to 2 AM EDT Sunday for ANZ231-233-234. Small Craft Advisory from 1 PM to 11 PM EDT Saturday for ANZ236. Small Craft Advisory from 1 PM Saturday to 8 AM EDT Sunday for ANZ235-237. Small Craft Advisory from 2 AM Saturday to 8 AM EDT Sunday for ANZ250. Small Craft Advisory until 8 AM EDT Sunday for ANZ254>256. && $$ SYNOPSIS...KJC/BL NEAR TERM...Belk/KJC/BL SHORT TERM...KJC LONG TERM...BL AVIATION...Belk/KJC/BL MARINE...Belk/KJC/BL CLIMATE...Staff
Area Forecast Discussion
National Weather Service Gray ME
1132 PM EDT Fri Mar 18 2022 .SYNOPSIS... A low pressure system will pass northwest of New England on Saturday night, bringing mostly rain to the region. Sunday, drier conditions arrive on a northwest wind for the start of the next work week with dry conditions near the coast and snow showers in the mountains. High pressure passes to the south through early week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 1125 PM Update... Minor update to account for latest conditions across the forecast area. Still awaiting fog to develop as moisture continues to pool in the lower levels of the atmosphere. Eventually, the marine layer will push onshore, allowing for drizzle to form as well, mainly in western Maine and much of New Hampshire. Will make minor adjustments to pops and temperatures for the near term portion of the forecast. In terms of temperatures, wind fields have begun to veer to the northeast at areas such as KWVL, KAUG, KPWM and KRKD. This will allow for cold air advection overnight across portions of the region as the precipitation arrives late tonight and Saturday morning. Nevertheless, current readings are lagging the colder HRRR and 3 KM Nam solutions, at least for the near term portion of the forecast. However, a brief period of mixed precipitation continues for northern areas. Hence, a Winter Weather Advisory remains in place. Prev Disc... Very warm day will wind down this evening as clouds begin to increase amid moistening mid/low levels. Some radar reflectivity over northern VT and southern Quebec should remain elevated as dew depressions are still quite wide. Will see effects of sfc moisture advection along the coast late this evening. Onshore breeze has already infiltrated along the coast, with temps in the 40s along the beach with 60s just a bit further inland. Expect fog to redevelop late, along with some drizzle for the NH coast. Satellite imagery depicts a bank of this low stratus and fog about 26nm off the coast, with a dodge inland over the last few frames. HREF guidance also brings these low ceilings back in with some restrictions to visibility. The main weather maker for the next day or so is still pivoting over IL, and will slowly track towards New England overnight. Have trended precip arrival back a few hours, but overall expect clouds to continue to increase this evening, with light rain showers arriving after midnight. Will see cool air pushing in at the surface from the north overnight, and this will be key north of the mtns and foothills for precip types Saturday. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... Low pressure will advance into the Great Lakes Saturday morning, with rain expanding east along a warm front pushing north. Cool temperatures at the surface should be at or around freezing for much of the western mtns and some valley foothills. With warm air pushing in aloft, expect the chance for some freezing rain at the cooler spots north of the mtns. The usual CAD mechanism will help prolong this pool of cold air, and thus issued a Winter Weather Adv here with the chance for a glaze of ice. After such a warm day Friday, have limited the area of coverage to just north of the mountains, especially because the weak push of cold air has a limited amount of time to advect in. With precip shield lifting north, showers will increase in coverage and intensity through central NH and ME. Expect some coastal enhancement for QPF and rain rates along the coast, as well as upslope regions of the mtns. Weak secondary low development off the ME coast could accentuate these rates further. Max QPF is forecast to be along the Midcoast. In addition, did further the mention of thunder chances for the coast and coastal waters. While there will be a steep low level inversion, instability aloft is decent with 200 to 700 j/kg of CAPE during the Sat evening hours. Have restricted this to the coast and southern NH w/ best lift and instability outlined by NAM/RAP/NBM. Showers will being to taper Saturday evening, west to east, with some mountain showers remaining. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Overview: Departing low pressure on Sunday will allow for a return to drier weather through early next week with just some upslope showers possible across the north and mountains. Mean shortwave troughing will persist through early next week, which will help to keep temperatures near to slightly above normal. Another storm system may then impact the area late next week with both rain and snow possible. Impacts: Little to no major weather related impacts are expected through at least the middle of next week. Forecast Details: Low pressure will continue to more northeastward over southern Canada on Sunday as high pressure begins to build to our west. Any rain across mainly eastern areas will end by mid morning but upslope showers will continue throughout the day across the north and mountains. As the system departs it will begin to drag down colder air from the north and therefore the rain will likely begin to mix with and change to snow across the mountains and minor accumulations may result. High temperatures on Sunday will still be well above average with many locations south of the mountains once again making a run for the 60 degree mark. Temperatures on Sunday night will remain mild for March with most areas staying above the freezing mark. A cold front will then cross the area on Monday morning but ensemble and deterministic guidance indicates that this will be fairly moisture starved. Nevertheless, still expecting a few rain and snow showers to develop across the north and mountains but given low QPF any accumulations will be on the light side. Behind this front high pressure will begin to nose into New England from the west, which will result in an increasing PGF over the area as low pressure meanders north of the Canadian Maritimes. This combined with daytime heating will allow for good mixing to occur and thus expecting a breezy stretch of weather through Tuesday. Given this setup went above NBM winds for this portion of the forecast. High temperatures on Monday will generally be into the 40s and lower 50s south of the mountains with readings on Tuesday about 5-10 degrees cooler. Winds will weaken on Wednesday as high pressure moves overhead and this will allow for subsidence over the area which will keep us dry as temperatures rebound a bit. Forecast confidence then decreases as we approach the end of next week as uncertainty remains on a storm system that will be moving through the upper Midwest and Great Lakes region. While there is moderate confidence within ensemble solutions that precipitation will occur with this system across our area there is much lower confidence in precipitation type and amounts. Taking a look at WPC cluster analysis 500 mb EOF patterns it can be seen that uncertainty remains in both the position and timing of a trough that will be swinging east out of the Ohio river valley, which is impacting both QPF output as well as temperature profiles. Did go ahead and delay PoPs compared to NBM during the Wednesday/Thursday timeframe as NBM was faster than the EPS/GEFS solutions and forecast soundings indicate that there will be a plethora of dry air within the low to mid- levels initially.. Over the coming days these details should begin to become more clear but for now would expect a return to more unsettled weather during the late week period along with near normal temperatures. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... Short Term...VFR this evening, with drizzle and fog returning to coastal TAF sites this evening and overnight. All sites remain MVFR/IFR with incoming rain and mist Saturday. Some FZRN possible a KHIE early Sat. LLWS will also be possible Sat evening at coastal sites. Long Term...Low pressure will depart to our northeast on Sunday with improving flight conditions throughout the day from west to east. Across the north continued SHRA/SHSN due to upslope flow will result in some flight restrictions. VFR conditions return early next week but northwest winds will be gusty each day with gusts up to 30 kts possible. && .MARINE... Short Term...SCA conditions will be met tonight amid onshore flow w/ increasing wave heights. SE winds will slowly increase overnight, with gusts to 25 kt Saturday evening as low pressure passes north of New England. Long Term...Marginal SCA conditions are possible on both Monday and Tuesday of next week with offshore flow prevailing. && .HYDROLOGY... Most interior rivers are showing a response to melting in interior watersheds. Due to well above freezing temps and dewpoints today, snowmelt should be plentiful with SWE loss even in the lower elevations of the mountains as the snowpack has ripened. A weak cold front will push south tonight bringing in cooler near freezing air by Saturday morning. Mixed precipitation changing to rain is expected on Saturday with more run-off anticipated across the Whites, than further north in the Western Maine mountains. The rain and snowmelt could lead to a few rivers reaching action stage by Sunday. With the increased CFS flow coming and the warm temperatures, the remaining river ice could flush out this weekend on many interior river systems. Ice jam flooding threat still seems to be limited due to multiple freeze/thaw cycles over the last month helping to rot and thin the ice in many areas. Even so, the potential for ice jam flooding over the next 36hrs can`t be completely ruled out, especially on the Pemi where a previous jam is still restricting flow near Plymouth, NH. Overall, good chance for northern river system to flush their ice this weekend. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Winter Weather Advisory from 6 AM to 2 PM EDT Saturday for MEZ007>009. NH...Winter Weather Advisory from 6 AM to 2 PM EDT Saturday for NHZ001. MARINE...Small Craft Advisory until 3 AM EDT Sunday for ANZ150>152-154. && $$ NEAR/SHORT TERM...Cannon LONG TERM...Tubbs
Area Forecast Discussion
National Weather Service New Orleans LA
847 PM CDT Fri Mar 18 2022 .EVENING UPDATE...Quiet night with clear skies and cool conditions but hourly temps have dropped a tad slower than expected. This is likely due to the strong winds just off the deck still. 00z sounding still had 20kt of winds at 500ft aand VWP at 01z had 25kt in the first gate. This will keep things mixed and slow down radiational cooling as previous forecaster mentioned. Unless these winds just fall off a cliff temps will just continue to drop slowly but steadily. If winds find a way to really relax in the LL we could see temps plummet just before sunrise but that is looking less likely. Only real adjustment to the forecast was to fix hourly temps as morning lows still looked good for the most part however, we did raise a few locations 1 or two degrees. That said it still looks like lows will be in the mid 40s to mid 50s across the region. /CAB/ && .PREV DISCUSSION... /issued 432 PM CDT Fri Mar 18 2022/ SHORT TERM (This evening through Sunday Night)... All severe weather along a pre-frontal trough has drifted east of the area this afternoon/evening, as we reside between this departing convection and an approaching cold front from the west. Winds have remained elevated this afternoon following PBL mixing, but with the bulk of CAA/drier air residing behind the front, we were able to warm up nicely this afternoon reaching the lower 80`s for many. HRRR guidance this afternoon doesn`t develop any shower or convective activity along this front, with very little notable sfc frontogenetic and dynamic ascent at play enough to offset a building strong low-level subsidence inversion. Only expecting a subtle wind shift later this evening from the northwest followed by cooling temperatures and drier dewpoints filtering in. Winds remain light/occasionally breezy out of the northwest tonight following the passing front, with probabilistic guidance really not hinting at winds shutting off with surface high remaining to our west. Not going to aim too low below blended guidance tonight as winds should offset maximized radiational cooling processes regardless of clear skies. Quite the pleasant weekend ahead as the aforementioned surface high builds into the area. Some patchy mid-level altocumulus possible Saturday with a stretch of H5 moisture riding progressive SW/NE flow ahead of a weak positive-tilt trough. Made minor adjustments to afternoon dewpoints to account for strong PBL mixing, with afternoon highs edging between deterministic and 75th percentile ensemble NBM guidance. We`ll likely see the coldest morning early Sunday with high pressure in control helping to promote strong sfc/low-level radiational cooling. Edging between the deterministic and 25th percentile ensemble guidance to account for a more plausible range of temperatures, with emphasis on drainage locations. The positive-tilt trough passes east of the northern Gulf during the day on Sunday allowing us to enter into a building ridge pattern across the Plains, drifting east into the MS valley region with very little, if any clouds around (other than some patchy upper- level cirrus). Highs a few degrees warmer overall with the same bias towards warmer ensemble guidance. KLG LONG TERM (Monday through Thursday)... Starting out early next week, a strong, amplifying longwave trough axis building into the intermountan west, which will be the focus for the next developing major storm system. NAM/GFS guidance/trends illustrate plenty of very strong deep upstream vorticity all the way into northern Mexico, eventually causing the axis tip to become negative tilt and close off while the base axis splits over the northern Rockies. This in turn leads to two developing surface lows, one over the northern Plains and the other over west Texas. Meanwhile for us during the day on Monday, we begin to see deep-moist return flow building into the southern Plains. Origination source of the pull of deepest moisture is well far southwest into the Bay of Campeche with a pool of 70 degree dewpoints that never gets "swept out" by this front passing this evening, and is a big consideration into the degree of sfc to low- level moisture advection magnitude ahead of the developing low. Convection ignites across the southern Plains on Monday given strong developing dynamic ascent and building deep-layer moisture/instability. Meanwhile, we begin to transition into a developing veering sfc to low-level wind profile given noticeable expansion in low-level curvature per forecast hodographs. Moisture will slowly rebuild back into the area with time, all underneath partly to mostly cloudy skies. From here, it becomes a bit unclear if convection could potentially organize or develop into an eastward-surging MCS into the lower MS valley region late Monday/Monday night and greater confidence will come when CAM guidance reaches this time frame. It is possible some of this activity could breach our western or northwestern CWA, but am not 100% sold on this unless cold-pool propagation could overtake extending convection more eastward. Just depends on convective mode potential for now. Regardless, this closed upper-low does not move much centered right in the central US helping to strongly occlude the southern surface low. The speed of the low not moving much, helping to continuously promote strong sfc to low-level moisture advection originating from the deep/moisture-rich source mentioned earlier means we will have no problem spreading lower 70 degree Td`s all across the area, north into central MS. Any residual convection that drifts into our area will either dissipate or drift north late Monday/early Tuesday with most of the area starting off on the dry side other than some light, shallow coastal showers. Low- level ridging anchored offshore coastal Atlantic FL does illustrate some drying in the 850-700mb layer being drug north from the western Gulf, which could be an early indication at a subsidence/capping inversion which supports the idea at a mainly drier morning, but GFS soundings strongly illustrate deep-moist ascent eroding the cap with time, with convection igniting along the front just to our west around midday Tuesday. Widespread MLCAPE in the 1500-2000J/kg range combined with a re-developing 50kt+ 850 jet will support developing convection, likely in the form of a QLCS with some embedded cells/supercells. H5 temperatures in the -12 to -14C range and mid-level lapse rates around 7 to 7.5C/km will support large hail, with damaging winds and isolated tornadoes a risk as well. As with every system, this one holds challenges that may require close monitoring, especially as we get closer into this weekend. One item specifically; How long will the developing 50kt+ 850 jet reside in our area before drifting north, which would eventually lead to diminishing low- level winds as surface winds begin to clock more out of the SSW, reducing the tornado threat towards the east. Hard to say, and very hard to nail specifics this far in advance, and the latest SPC Day 5 Convective Outlook introduces a 30% probability area very much in the one area with greatest deep-layer shear/instability overlap all within peak diurnal heating. 12Z GFS soundings for KMCB for 18Z TUE, putting it lightly, is rather extreme and support the potential for significant tornadoes, extending north into central MS. This would be a system that will require close attention, as inhibiting factors we`ve seen from previous events (lack of deeper moisture return, whether cells will be elevated or not and where greatest dynamics would line up with convection) does not appear to be a major concern with this one. The only question remains the eastward and southern extent if/where low-level jet dynamics is greatest. But above all, will continue to closely monitor. The line of showers/storms along the cold front continues to parade east late Tuesday thru early Wednesday, likely weakening with time with the front racing through to follow. Wednesday is looking breezy and slightly cooler. Meanwhile aloft, the overall mid-level pattern gets rather complicated as this same upper-low drifting northeast becomes absorbed into a southern Canada shortwave, leaving lingering energy holding back into the four corners region. Northerly flow will support weak shortwave impulse riding south over the Rockies to kick this energy east, closing off within developing zonal flow to the north. This in turn could possibly place an upper-low somewhere over the southeastern US late week into next weekend, but many doubts remain this far in advance how this would impact our area, if at all. KLG AVIATION (18Z TAF DISCUSSION)... All rain and storms have departed the area to the east, with gusty westerly surface winds continuing across all terminals. Patchy low clouds remain, mainly across eastern areas, but will continue to clear out through the afternoon and evening hours with VFR prevailing. A dry cold front is expected to pass through the area later this evening into early tonight, with the main impacts being a wind shift from the northwest and remaining breezy with VFR continuing into early Saturday for all terminals. KLG MARINE... A passing cold front this evening/early tonight will re-introduce gusty northwesterly winds. Small Craft Advisories are hoisted back into effect to account for wind gusts upwards of 20-25kt with building wave/seas reaching 5 to 7ft, latter for 20-60nm zones south of the MS. High pressure builds in this weekend with calm/clear conditions. This high will shift east early next week with deep, southeasterly Gulf fetch helping to increase winds with wave/seas to follow. Next major storm system expected Tuesday and into early Wednesday with another strong front swinging through which will be followed by gusty northwesterly winds following into late-week. KLG && .PRELIMINARY POINT TEMPS/POPS... MCB 81 45 69 40 / 60 0 0 0 BTR 82 46 70 41 / 40 0 0 0 ASD 83 48 71 41 / 80 0 0 0 MSY 83 54 68 48 / 70 0 0 0 GPT 82 51 70 43 / 80 0 0 0 PQL 80 49 72 41 / 90 0 0 0 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...Small Craft Advisory until 10 AM CDT Saturday for GMZ532-536-538- 550-552-555-557-570-572-575-577. Small Craft Advisory from midnight tonight to 10 AM CDT Saturday for GMZ530-534. MS...None. GM...Small Craft Advisory until 10 AM CDT Saturday for GMZ536-538-550- 552-555-557-570-572-575-577. Small Craft Advisory from midnight tonight to 10 AM CDT Saturday for GMZ534. && $$
Area Forecast Discussion
National Weather Service New York NY
1006 PM EDT Fri Mar 18 2022 .SYNOPSIS... High pressure weakens this evening as a frontal system approaches from the west. The associated warm front lifts over the area Saturday morning and afternoon, followed by a cold front Saturday night. A broad area of high pressure will then build in through the middle of next week. Low pressure may impact the area for the end of next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Fog and low stratus are continuing to slowly move into the area from the south with much of Long Island seeing reduced visibilities. This should gradually spread northward into the overnight, perhaps a bit slower than initially anticipated. Other than that, this update accounts for the latest observations of temperature and dew points. The main concern overnight revolves around how much fog will return across coastal CT, and whether or not it expands inland. There is a chance that it will end up being more stratus over land, especially as the night moves along. The fog bank along and just off the Long Island coast has diminished somewhat earlier this afternoon. However, concerned that it will start to expand northward overnight as the boundary layer cools. The HRRR has been consistent on showing fog overspreading at least coastal sections, but could also expand well inland as well. Some factors that could play against dense fog include increasing middle and high level clouds and increasing low level flow, especially tonight. Have held off on a dense fog advisory, but will issue an SPS to highlight potential for areas of dense fog this evening. Otherwise, ridge axis both at the surface and aloft weakens this evening ahead of a southern stream shortwave that is lifting towards the Ohio Valley. Warm advection and increasing low level flow will increase through the night. Low clouds are likely and as mentioned above, areas of fog are possible. Low pressure associated with the shortwave will send a warm front towards the area early Saturday morning. A few showers may develop as the forcing increases, especially towards day break. Lows will likely be in the 40s for the eastern two thirds of the area, with lower 50s in the NYC and urban NE NJ corridor. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SATURDAY NIGHT/... The warm front will slowly lift across the region on Saturday. Confidence is not high that the boundary will fully lift north of the area, and it is possible it becomes stationary over or just south of the region. Parent low pressure will move across the Great Lakes through the day and the surface flow may end up a bit more SE than S. The marine influence in the low levels will help slow down the warm front progression and also keep conditions more stable over the region. Warm advection and some shortwave energy will lead to showers in the morning and early afternoon. This activity should diminish in coverage by middle to late afternoon. Forecast soundings do show limited elevated CAPE in the morning and a rumble of thunder cannot be completely ruled out. The trailing cold front will then approach in the evening and move across at night. Forecast soundings indicate more elevated instability in the evening and have continued to show a slight chance of thunder. High resolution guidance hinting at a broken line of showers along and ahead of the cold front. They do agree the line will weaken as it encounters the more stable low level air and maritime influence. SPC has highlighted a portion of Orange County in a Marginal risk, with a general outlook elsewhere. Even in Orange county low level profiles are inverted, so the severe threat there is very limited. The cold front should be moving offshore around midnight, bringing an end to the chance of showers and rumbles of thunder. Average rainfall for this evening looks to be around a half inch. Locally higher amounts are possible in any heavier downpours, but no flooding concerns given the quick movement of the activity. Temperatures on Saturday should stay in the 50s across much of the area, but could see some low 60s in the NYC metro. Lows Saturday night look to be in the 40s. && .LONG TERM /SUNDAY THROUGH FRIDAY/... The models were in fairly good agreement thru the extended, so the NBM was generally followed. Mainly dry wx Sun-Tue. The NBM is dry. There is wave invof the polar front that comes thru in the ECMWF and GFS Mon ngt that could put down a stripe of pcpn across the area. Decided for now to hold off on going abv the NBM with the ECMWF trending drier with the feature. Despite the colder airmass Mon and Tue, high temps several degrees abv climo with good mixing. Low pres emerging from the Rockies on Mon reaches the local area around Thu. This is progged to produce some rain across the CWA. Mainly dry Wed before the sys, then again on Fri behind the sys. Still some timing concerns this far out, so pops are not completely dry Wed and Fri. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... Weak high pressure continues to retreat offshore, while a frontal system approaches from the west. The associated warm front approaches from the south tonight and moves through the area on Saturday, with the cold front approaching Saturday evening. Conditions along the immediate coast have fluctuated a bit as low stratus tries to make its way onshore. Despite the slow start, conditions are still anticipated to drop into the overnight for most terminals. Low stratus and fog over the ocean is expected to make its way onshore through 6Z allowing conditions to drop to IFR/LIFR for much of the area. Some improvement is expected Saturday morning as showers move across the region and mix up the lower levels but mainly IFR conditions are expected to continue through much of the day Saturday. An isolated thunderstorm is not out of the question, especially toward the evening, but confidence is low at this time. Winds will be generally out of the SE less than 10kt but may become briefly variable overnight. Winds then veer gradually on Saturday as the warm front lifts through the area. There is a chance of LLWS for the easternmost terminals (KISP, KGON) during the afternoon. NY Metro (KEWR/KLGA/KJFK/KTEB) TAF Uncertainty... Amendments are likely for the timing of lowering ceilings/vsbys overnight to IFR/LIFR. .OUTLOOK FOR 00Z SUNDAY THROUGH WEDNESDAY... .Saturday Night...IFR initially becoming VFR behind a cold frontal passage. .Sunday and Monday...VFR. WNW winds 10-15G20kt. .Tuesday...VFR. .Wednesday...Mainly VFR. Chance of rain late. Detailed information, including hourly TAF wind component forecasts, can be found at: https/www.weather.gov/zny/n90 && .MARINE... Main concern on the waters through tonight is with dense fog. The dense fog advisory on the ocean and south shore bays remains in effect through tonight and goes into effect on the Harbor, LI Sound, and eastern LI Bays at 7pm tonight. The fog bank has diminished in coverage somewhat, but the expectation is it will expand northward this evening. Otherwise, winds and seas should remain below SCA levels tonight. There could be some seas to around 5 ft well offshore east of Moriches Inlet, but it looks marginal. Winds and seas then increase on Saturday to SCA levels. An SCA has been issued on the ocean starting at 8 am and goes through 6 am Sunday. Winds on the LI Sound Winds and seas on the non-ocean waters should remain below SCA levels on Saturday and Saturday night. A sca will likely be needed on Sun for all waters with gusty with gusty wly flow. The sca may be needed on the ocean for Mon, and perhaps again on Tue with mrgnl nwly winds and seas. All waters blw sca lvls on Wed. && .HYDROLOGY... An average of about a half inch of rain is forecast on Saturday. Locally higher amounts are possible in any heavier downpours. No hydrologic issues are anticipated at this time. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Dense Fog Advisory until 6 AM EDT Saturday for ANZ331-332-335- 338-340-345-350-353-355. Small Craft Advisory from 8 AM Saturday to 6 AM EDT Sunday for ANZ350-353-355. && $$ SYNOPSIS...JMC/DS NEAR TERM...JMC/DS/MW SHORT TERM...DS LONG TERM...JMC AVIATION...MW MARINE...JMC/DS HYDROLOGY...JMC/DS
Area Forecast Discussion
National Weather Service Mount Holly NJ
848 PM EDT Fri Mar 18 2022 .SYNOPSIS... A warm front crosses our region late tonight and Saturday morning as low pressure moves into the Great Lakes region. An associated cold front then moves through late Saturday afternoon or early evening. High pressure builds in Sunday night into Tuesday, although a weak cold front moves through late Monday. Low pressure is forecast to arrive later Wednesday into Thursday. && .NEAR TERM /THROUGH SATURDAY/... Forecast mostly on track this evening. Widespread fog lies over the ocean, and should spread west inland as the evening progresses. A Dense Fog Advisory may be needed for coastal New Jersey and coastal Delaware, but confidence is a bit low to warrant issuing one at this time. 18Z/18 NAM and latest HRRR have an area of showers passing through the northern zones sometime after midnight through prior to daybreak as a warm front lifts north through the region. After the showers end, there lingering low level moisture will result in patchy fog. It is possible for fog to lower to Dense Fog Advisory levels of 1/4 mile or less, but confidence is low. Otherwise, with increasing low level moisture over the area, patchy fog is likely to develop throughout the region. With the clouds and increasing moisture, low temperatures will be well above average for this time of year, in the low to mid 50s. An unsettled day is expected Saturday with a couple of things to watch. Occluding low pressure will steadily track northeastward through the central Great Lakes during the day. The warm front will continue pushing into our region during the morning hours. As usual, it will be a struggle for the warm front to push through. It will eventually get through most or all of the region, but may take until well into the afternoon up north. Along and ahead of it, low clouds, patchy fog, and scattered showers will remain possible for most of the morning. Heading into the afternoon, there should see breaks in the clouds, especially to the south. Temperatures will be tricky on Saturday. Fairly strong warm advection develops aloft behind the warm front. Winds at the surface will increase and turn more southwesterly in the afternoon as the region gets into the warm sector. As the sun starts to break out, it should turn into a mild day with many places rising into the 70s. If the area clears out a little sooner, the southern half of the region, away from the coast, has a shot to make a run at 80, but not willing to go that far in the forecast due to cloud cover concerns. There remains a threat of severe weather on Saturday, though the setup looks quite a bit different than it did yesterday. For southern portions of the area like Delmarva and southern New Jersey, it appears increasingly unlikely that there will be sufficient forcing to overcome a significant amount of dry air aloft. Convection will likely attempt but fail to initiate, with an isolated shower or storm possible but updrafts quickly getting choked off by dry air. Instead, we are now more focused on portions of eastern Pennsylvania and northern New Jersey. Guidance has trended towards a much stronger mid-level shortwave tracking just northwest of us by Saturday afternoon or evening. Lift from this shortwave and a prefrontal surface trough are likely to yield convective development over east-central PA during the afternoon, propagating east-northeast towards northern NJ. Some of these storms could become strong to severe. Regarding hazards, expect damaging winds to be the main threat given very strong mid-level flow, and dry air aloft to aid in momentum transport via evaporation/DCAPE. Mid-level lapse rates still look better than normal, which could contribute to a hail threat. Not expecting anything crazy due to modest SB CAPE (around 1000 J/kg), but expect there will be a number of small hail reports and possibly some marginally severe ones. The tornado threat is not quite zero, but seems low. With strong forcing and very strong but unidirectional shear, think any discrete cells would rapidly grow upscale, and QLCS tornado potential (if a QLCS develops) looks limited due to boundary parallel shear vectors. Overall, this is definitely not looking like a widespread severe outbreak, but is the first "traditional" warm season convective setup that has developed this year. && .SHORT TERM /SATURDAY NIGHT/... A cold front associated with the Great Lakes low will move through overnight, with dry weather behind it. The front itself is unlikely to trigger any convection. Overnight lows are forecast to fall into the mid 40s to low 50s. Think westerly winds will stay up just enough behind the front to prevent another round of fog, but can`t totally rule it out if winds end up lighter. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Summary...Temperatures generally near to above average with a main system moving through later Wednesday and Thursday. Synoptic Overview...No major changes to the long term forecast with this update. The large scale upper-level pattern becomes less progressive through the week, with a ridge building over the East and a slow moving longwave trough over the central portions of the country. As this trough slowly advances eastward, a storm system looks to arrive in the later Wednesday and Thursday timeframe. For Sunday...A transition day as Saturday`s system pulls away and high pressure begins to build to our southwest. Deeper mixing develops and a notable breeze is expected with wind gusts up to 30 mph. There is not a lot of cold air behind the cold front, however a moisture layer should result in stratocumulus across much of the area for a while. Despite the cloud cover, downsloping flow should result in temperatures above average (in the 50s and low 60s). Overnight lows Sunday night are forecast in the mid/upper 30s to low 40s, though could end up cooler if the boundary layer fully decouples and as the sky becomes mostly clear. For Monday and Tuesday...High pressure over the Southeast should provide mainly dry and mild conditions. Plenty of sunshine Monday and a steady westerly breeze will lead to good mixing and temperatures rising into the low to mid 60s. A cold front looks to move through late Monday as Canadian high pressure presses southeastward. This front looks to move through dry. Tuesday is a little more uncertain as the front should stall to our south. If the strong subsidence with the eastern Canadian high is less this far south, then more cloudiness will occur across much of our area. For now, maintained a dry forecast but continued with more cloud cover and hold temperatures at least few degrees below Monday`s values. For Wednesday and Thursday...Guidance indicates a large storm system develops over the center part of the country and slowly pushes east, with an increasing chance for precipitation in our area by late Wednesday and Thursday. However, high pressure pushing south out of Canada may try to delay the arrival of it. For this reason think NBM may be a bit fast and we maintained continuity with previous forecast which delays the arrival of the precip until late day Thursday into Thursday night. The high to the north will also draw cooler and drier air into the region and potentially even introduce wintry precipitation types mainly across portions of the northern areas. This is a result of an overrunning setup with colder air lurking to the north. Given the uncertainty, did not make any significant changes. Friday...A lot of uncertainty in the forecast at this lead time as the GFS builds in high pressure into the area behind Thursday`s system while the EC fractures the upper trough associated with the system. This brings another piece of upper level energy through Friday bringing more showers. Given the uncertainty we stayed with NBM guidance which depicts slight chance POPs across the area. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight (00Z through 12Z)...Overall, a low confidence forecast throughout. VFR initially. Fog and stratus will spread west into KACY and MIV early with LIFR and VLIFR conditions likely. Otherwise, an area of showers spreads through the other terminals sometime after 05Z through 12Z or so. Once the showers end, fog and stratus with IFR/LIFR conditions will develop late and through daybreak. Light SE winds. Saturday (12Z through 00Z)...Mainly IFR, locally lower, in the morning with fog, low clouds, and showers. Slow improvement to MVFR/VFR from south to north is likely during the late morning and early afternoon hours. An area of SHRA and TSRA may affect most terminals except for KMIV/KACY from 20Z through 00Z with gusty winds and hail possible. LGT/VRB winds in the morning, becoming S 5 to 10 kt, then SW 10 to 15 kt with 20 to 25 kt gusts late. Moderate confidence. Outlook... Saturday night... A lingering shower or tstm is possible mainly north of PHL through about 02z. Otherwise, VFR. Winds shifting from southwest to west at 5 to 10 kt. Moderate confidence. Sunday...VFR. West-northwest winds 10-15 knots with gusts to 25 knots, diminishing to 5-10 knots at night. High confidence. Monday and Tuesday...VFR. West-northwest winds around 10 knots. Moderate confidence. Wednesday...Mainly VFR through at least the first part of the day with a system arriving late day into Wednesday night bringing possible restrictions. Winds becoming east/southeast around 10 knots. Low confidence. && .MARINE... Through tonight... A Dense Fog Advisory is in effect for the Atlantic coastal waters. Reduced visibilities are expected to continue through the night. The Advisory does not currently include Delaware Bay, but fog development is possible there also. Otherwise, sub-SCA conditions are expected with southerly winds 10 to 15 kt and seas 3 to 4 ft. Saturday-Saturday night... Fog should gradually diminish on Saturday morning or early afternoon. SCA conditions are expected to develop. Seas building to 4 to 6 ft for late Saturday morning through the night. Southerly winds turning more southwesterly and increasing to 15 to 25 kt with gusts up to 30 kt, before gradually decreasing and becoming more westerly overnight. Rain showers possible. Outlook... Sunday...Small Craft Advisory conditions likely due to wind gusts to 25 knots and elevated seas. Monday and Tuesday...The conditions are anticipated to be below Small Craft Advisory criteria. Wednesday...Winds/seas start to increase ahead of the next system with Small Craft Advisory conditions possible beginning late day or at night. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Dense Fog Advisory until 6 AM EDT Saturday for ANZ450>455. Small Craft Advisory from 11 AM Saturday to 6 AM EDT Sunday for ANZ450>455. && $$ Synopsis...Fitzsimmons/Gorse Near Term...MPS/O`Brien Short Term...O`Brien Long Term...Fitzsimmons/Gorse Aviation...Fitzsimmons/MPS/O`Brien Marine...Fitzsimmons/O`Brien