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Meteorological Spring hits March 1st, thus begins the quiet season on the forums. This thread should suffice until fall for any long range disco. I doubt the last flakes have fallen this year but I don't really expect another widespread winter threat either. It was definitely a Plateau to Western Tennessee winter. Tough for Eastern areas not to do any better with virtually the entire month of January being BN for temps. The flood threat, as it always seems to be these days, is definitely elevated again this spring. The severe threat, I'll leave that to Jeff, Jax, and the rest of the severe gurus. -
Please follow NWS statements on the potential for SVR midday Friday. Otherwise, scattered showers develop near midnight becoming bands of briefly moderate to heavy showers during the daylight hours, ending from west to east by around nightfall Friday. Rainfall generally in the 0.4-1.5" range;. Iso 2.5" possible. Gusty surface winds to ~40 MPH BUT please follow NWS SPC on the marginal potential for an embedded SVR storm, even Tornado, due to the strong wind fields aloft and marginal instability for connecting to the surface. This latter SPC threat is the primary reason for beginning this OBS-NOWCAST thread. EDIT: 444PM/11: Guidance seems to be ramping up surface gusts I95 eastward midday Fri...gusts 50 MPH. The above is part ONE. (edit 626P/12 Will post CoCoRaHs data as best I can around 8A Saturday) Part TWO is Saturday--- a 6 hour period of colder notable showers. Edit 444PM: Modeling (some) is trying to focus energy (CAPE etc) for a thunderstorm vcnty NYC. If that happens, hail would also be possible. [EDIT 626P/12 Part Two is on for Saturday midday-afternoon. HRRR has a 'chance' of thunder north of NYC... but its modeled guidance suggest T might occur down to NYC. Slight snow acc Poconos midday Saturday.] Part Three is late Sunday-Monday with potential for general light precip with embedded moderate, and even some minor wet snow accumulations highest terrain northwest of I84. Let's focus on Part ONE when it arrives Friday, and we'll get to separate OBS threads, if needed, for parts Two and Three, if that is okay with everyone and if needed. -
Spring has sprung and it's brought rain again this year. After a fairly dry two weeks that actually had a few brush fires in the area the rain has returned. 2.75 inches in the last 24 hours. A 3+ inch event last week. Suddenly the "dry" March is well AN on rainfall imby with over 7 inches so far. A dry Friday looks like it's going to give way to another bout of heavy rain Saturday into Sunday. Possibly another 10 inch month this month. Had more of them in the last 24-30 months than most 10 year periods produce.
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We don't get a ton of activity once severe season ends, so this thread should carry us til September/Fall.
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Left the botched Title here Wed morning 440AM: Longest heat wave of the season so far, "possible" Sun Aug 8 to possibly Wed Aug 18. Heat: 00z/4 EPS continues 19C Mon-Thu before slight cooling thereafter, but that may be in part climo? 00z/4 GFS has made an abrupt change on backdooring and now has potential 90F heat NON-marine influenced I95 corridor for many days. There could be interruptions due to convection-sea breezes but by and large a lengthy hot spell seems to be increasingly modeled. NAEFS suggests that the above normal temps may continue through the 18th, possibly longer. Heat indices may rise to 100-105F in the I95 corridor (non marine), for two days next work week. This is a time of lush vegetation that contributes to high dew points and it appears dewpoints should rise into the low-mid 70s, as modeled, at times next week. The first hottest HI day should be next Tuesday or Wednesday (10th-11th). The 00z/ 4 GGEM is not favoring a big heat wave and WPC Day 6-7 for next Tue-Wed MAX HI is generally mid 90s... so there is uncertainty although I sense NCEP NDFD blend may be muting the potential heat. We will know more in a week. The reason for this thread: This pattern gives appearance of providing non marine areas with their longest spell of summery 90+ heat. EWR current max stretch is I believe 5 days. This doesn't mean historic numbers but does suggest precautions will need to be taken each afternoon-night in the interior urban centers. QPF: in addition to the 1-2" of rain that at least eastern LI should receive later today-Thursday morning, there could be sea breeze induced thunderstorms in the high CAPE over a portion of the LI shores next week, that could drive up iso max rainfall there to 6". The pattern also suggests, with waves of PWAT near 2" next week and KI in the mid 30s, that there may be small pockets of brief excessive rainfall and wet microbursts in an otherwise light westerly steering flow (generally less than 25 knots next week) I95 corridor northwestward. Where, when or IF? It doesn't look like it gets too warm aloft at upper levels (500MB) to stifle thunderstorm growth, until next weekend at the earliest (14th). fwiw: Marginal 90F appears possible this Fri-Sat (6-7), but the heat portion the thread concentrates from the 8th-possibly as long as the 18th with the initial primary focus next Mon-Fri (9-13)
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Just borrowed on some of the on-going themes for July... as written in June threads, with past 40 year temperature trends supporting some of our posted long range statistical outlooks including those of CPC through today-June 28.
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Started a topic that may not bear as much fruit as the recent ELSA of this past week but with the attached 6 hr FFG fairly low now in the immediate NYC suburbs, thought it might be good to heads up some of the potential. Sun afternoon-Tuesday---warm frontal residuals and moisture pooling in weak low lvl WAA and halfway decent winds aloft that diminish considerably on Tue, I think there will be pockets of FF producing thunderstorms that could yield spot 5" amounts in that 60 hour period (slow movers Tuesday). Instability is related to considerable CAPE over 2000J in parts of the area Mon and Tue. Warm fronts can be big rainfall producers and so my thinking is the biggest problems will be I80 south, though some of the modeling gets things cranking up to I84. Suspect a few SVR Wet microbursts each day, especially Monday and Tuesday. Additionally the heat wave should begin Tuesday in the non-marine wind influenced coastal plain with the HI 95-100 Tuesday, Wednesday, Friday and possibly right through the weekend if the 12az/9 EC op is incorrect and the GFS as of 18z/9 is correct on 576 thickness in our area next weekend. My guess, once the heat wave starts, the debate shifts to it's big break... right now I favor longer than the EC and quite possibly lasting through next weekend. Hottest day(s)?: I think Fri when some of modeling has HI 100-maybe 105 near NYC. SVR seems likely to me on Wednesday the 14th due to increasing wind fields, then a drying out Thu-probably nothing that day, with fairly widespread SVR looming either next Fri or Sat when not only CAPE seems pretty large, but wind fields increase quite a bit and more easily sustain a big outbreak. TT toward next weekend increase a bit toward 48-50..not a huge svr signal but together with the wind fields and CAPE, should be interesting. In Summary: Lower FFG, high CAPE suggest pockets of excessive rainfall coming this week, along with SVR storms, esp Mon, Wed, FRI. Who gets the worst and when?? It does appear this will be more than the routine summer week, once again, with the big 500MB ridge along the east coast and troughing hugging the Great Lakes.
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- flash flooding
- severewx
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The evolving pattern this coming week is continuing to model high CAPE (Heat Index NYC metro non-marine influenced near 100F) Tue-Wed and even Thursday afternoons with enough wind aloft and instability to permit one or 2 days of SEVERE storms in our area. Tuesday SVR appears relegated North of I80 (mainly NYS/CT). Wednesday to me looks like a potentially big day, especially I80 region northward with TT in the lower 50s, big CAPE. Thursday into Friday: Uncertainty on evolution but big CAPE and instability probably remain in the vicinity of our subforum. It too could be a severe day, however of interest is the eventual position of the frontal boundary. IF, it drifts down into our subforum with light north-northeast flow north of it, then it seems to me the projected path of decayed ELSA wind fields and moisture plume - convergence (925-850MB southerly flow overrunning a cool frontal boundary, ranging up to the 200MB RRQ of jet located in se Canada) would promote the potential for a Predecessor Rainfall Event (PRE) as documented in research by NYS associated well known mets. Have added a couple of their composites. These 4+" events occur 24-36 hours in advance of the TC, located hundreds of miles north or northeast of the TC even though the TC itself can miss to the south. If it doesn't and tracks over the PRE then that magnifies the potential sub-basin (mesoscale) trouble. As we are aware, we're starting to pile up the water across our subform so this potential result-NOT guaranteed, should be monitored and we'll see if it can occur, fritter, or displace north of our subforum. I'm doubtful if the potential displaces south of us. My guess is we'll know by Tuesday or Wednesday. In the meantime, I think we can expect severe storm wind/hail in parts of our area during midweek, along with possible storm cluster FF in PW air of 1.6", and probably should monitor the evolution of ELSAs ensembled wind fields up this way. Composites are added, as well as 00z/3 EC PWAT for late Thu (showing the TC well south but PWAT axis up near here). This is imperfectly modeled, the speed and location of ELSA and associated wind fields will adjust and affect the results. Let's see how this may breakdown and whether or not we can pick up ISOLATED 4-6" new rainfall between Tue-Fri in parts of our area-ISOLATED. WPC went to press this morning with a general 1"+ for our area, which supports embedded isolated heavier. You probably recall around the 28th-29th they had our entire area 1.5" for the current ongoing event with general 2"+ central and S NJ. Appears they did quite well. 638PM Monday July 5- EDITED Title to include ELSA- Too much modeling is drifting its track within range of coastal NJ and LI for Tropical Storm considerations Thu night-Friday AM. While it's not certain to make a direct second landfall across LI/southeastern New England, think it best to open the door a little more, at the least for 4+" rains this week combined convective outbursts and whatever Elsa.
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Uncertainty as always but SPC has expanded their D1 into our area, and the attached 12z HRRR suggests iso 50-55KT gusts into PA/NJ/LI, mirroring the 00z/19 EC OP. Looks to me like 90-95F today (non marine), decent CAPE. The severe risk suppresses south tomorrow, but WAA begins late Sunday and then both Monday and Tuesday look steamy 90-95F inland, depending on sunshine which also implies cirrus from Claudette possibly tempering heat/cape. This should result in pockets of heavy convection, and where training, could see a ISOLATED max of 4" by 6PM Tuesday. Otherwise, the necessarily more conservative early Saturday WPC outlook works. So while not a big deal (yet) for heavy rain, the convection later today, later Monday and Tuesday could provide some news (damage) footage, including lightning related. Walt
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HRRR and 3KNAM offer a squall line of sorts in the warm sector 6P-10P, accentuating NJ s of I78 where the Significant Tornado parameter and Supercell composite indices are notably large. This is on the tail end of of 75kt 850 sw jet over LI, just ahead of a cold front with marginal CAPE. (That 850 jet initially causes the midday deluge's in parts of our area with possible flood advisory for poor drainage flooded roads). Should not be much hail, if any. Max Updraft helicity 2-5KM has some swaths across much of the region. Not saying it will happen but should at least have gusts near 40 kt with the line as per HRRR/EC gust algorithms. HRRR prior to 09z/28 has isolated G50-60KT. R# looks more permissive than for this past Fridays wind advisory event . I think most of any severe should be NJ shore but could extend east. Even a small chance of G40-45KT in the strong southerlies for LI, well ahead of the squall line., NWS OKX has a wind advisory posted for the OKX forecast area later this evening-Monday. That should verify with scattered G40kt, especially 3AM-Noon Monday, associated with the cold core arriving (CAA) and pressure rises.
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The tag features the damaging wind in the dry air, especially mid-late Friday afternoon at the warmest time of the day. The severe tag is low risk (Marginal part of the area as per SPC D2 outlook). There should be bands of heavy showers, isolated embedded thunderstorms, moving east northeast across the area between 5A-2P, but the inverted or isothermal sounding should limit transfer of gusts during the morning. However, he last possible line along the cold front midday-early Friday afternoon might allow for isolated SVR as the sounding becomes more unstable to the surface? Please add Friday guidance and reports for Friday's event to this thread, keeping OBS and NOWcast embedded within this thread as well.
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OBS and NOWCAST as this storm unfolds. Power outages may limit some of our participants from adding data. Be prepared for losing the internet, even if you own a generator.
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- damaging wind
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Low to moderate confidence for a damaging wind event (scattered pockets). We're about 48 hours away and within a time that we should be looking for a possible significant event. Not a lock for damaging south wind gust 40-60 MPH in squalls, with an isolated SVR thunderstorm associated with a cold frontal passage, or... brief westerly wind gust to 45-50 MPH within 3 hours of the CFP - associated with strong dry air advection and modest pressure rises. The NAM/UK/EC have 65-75 kt winds near 850 MB at about 7PM Sunday over LI. RGEM even stronger. Op GFS is weakest. As we draw closer to Sunday afternoon, intensity of the wind fields and instability-and any squall lines will need reassessments. The upper 50s SST may limit transfer but lapse rates and any squall lines/kinks or breaks in the lines will be important discriminators for a sizable power outage event on LI/CT. Further west... if damage is to occur in NJ/se NYS, I'll look at hill towns first, and then along the immediate NJ coast, and especially IF, the currently modeled wind fields maintain intensity and can begin sooner as per the RGEM, which is the strongest of the models that I've seen from the 12z-18z/13 cycles. So, to avoid a damaging wind gust, NAM/RGEM/ECMWF/UKMET 65kt+ wind gusts need to weaken 10-15 kt, or a triple point low forms just s of LI. Have three 12z/13 RGEM graphics (slower than the NAM) 4P-7P-10P, added a prob for wind gusts 40+ MPH by the weaker 12z/13 GEFS. Added 18z/13 3K NAM turbulence Richardson # overturning graphic for LGA that is solid .25 up about 925 MB which may favor spotty mixing on the southerly flow and more widespread mixing on the slightly weaker westerly flow behind the front. Also added the 3K NAM modeled wind field from the 18z/13 3K NAM---also for LGA. EC has 3 successive cycles of 40+ MPH for LI/CT and past two cycles 50-60 MPH. Uncertainty on 60 MPH but confidence for ~40, scattered 50 MPH is at at least moderate. RGEM timing below is slower than the 3KNAM. By the way...models have the showers moving east at 62kt. 722P/13
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I'll be away for a large portion of this time frame so creating a possible avenue of posts, IF SVR materializes. Have seen a few models with a separate more northerly strong shear zone near I78 to southern LI early tonight. Added a couple of graphics. This matches the SPC D1 Slight Risk. While I think most of the SVR will be south of our forum, needed to cover for a possible potent developing event. You'll know by 7PM what's moving through and/or near KABE. Keep alert on your radar data. IF a supercell develops...real good chance of 1-3" in 30 to 60 minutes. Again, low prob for our area but could not ignore some of the modeled guidance.
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Just a brief note to ensure all know mPing has returned this afternoon. We'll need to reload the app (delver then add). Its is valuable information-ground truth check on radar. It works. Apparently it returned last evening.
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- severewx
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Monday-Tuesday: Issued a low confidence topic for more widespread heavy thunderstorms with potential for 2-3" max rainfalls (this was modeled for Sunday several days ago by the EC-but delayed for most of our area-except Ocean County- til Monday). KI is up, actually quite high for Monday morning so we may get a quick start Monday. PW up to near 1.8". Cannot rule out an isolated SVR Monday afternoon but the two day topic includes Tuesday's SPC slight risk. SPC sees more detailed model information than I, so despite my concerns about general nw 850MB flow which tends to be negative for convection holding together east of Appalachians, I've included Tuesday per SPC yesterdays D4 and todays D3. I could see best chance SVR early in the day but this hopefully will be improved as we draw closer. Plenty of wind in the sounding and enough CAPE/KI for sure, but don't quite like the 850 flow. 858A/23
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Since PHI issued a FF watch for much of its area yesterday, and then OKX followed suit this morning for parts of NY metro; have started this topic. Yes, potential exists for Flash Flooding and a few small areas of 4+ inch rains by Noon Friday, but model guidance is not overwhelmingly favorable for our NYC forum area. Northeast NJ, because of its infrastructure, and previous soil moisture condition is most vulnerable. But, best convergence for heavy convection appears to favor I78 southward for the entire period (south of more vulnerable ne NJ), with heavy convection possible further north to FWN-HPN-BDR up there only this afternoon. (for now, it seems se NYS and much of interior CT will miss the big stuff these next several days - keep watering the flowers from time to time). More than adequate CAPE and PWAT exist for heavy rainfall, KI are not pooled excessively in our area so far, but enough exists with a frontal boundary in a fairly light wind flow aloft. SVR: Since winds aloft are light, SVR if any, should be very limited, and probably only the I78 region southward-subject to modeling change. In summary: There should be organization for 1-3, short duration episodes of very heavy rain the next several days, especially in NJ. It seems most of this will be in the southern part of our NY forum area and even though the FF guidance is not as vulnerable in Monmouth, Ocean, Mercer counties--- that may be where the predominant threat for excessive rain is greatest-per WPC's morning excessive rain outlook for today-tonight. 610A/12
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LOW chance of exceeding 4" but this is worthy of awareness, I think. Have reviewed most of the typically used 12z/6 modeling, and WPC/SPC guidance. The scenario is a weak wsw flow aloft at 700 mb, over a very moist (near 15C dew point) 850MB vorticity rich wind shift across NJ (sse-sw) with 500mb vorticity maxima passing newd within an approaching 500mb trough that doesn't swing its broad axis through our NYC forum until about 12z Saturday. Dewpoints are already generally in the mid 60s with PWAT 1.6-1.8",-not overly wet, but with slow movers, plenty to allow for potentially excessive rainfall. How it all works is not clear and odds are that more than 4" of rain won't occur but have seen 12z/6 SPC HREF MAX precip guidance nears 10" in 1 spot of east central NJ and spotty 10+ s of LI. Best axis: unsure but for now along or s of I80 through LI or southward down to near I-195 (Ocean Mercer) counties. It should light up late tonight in central or northern NJ into LI and continues into forenoon Friday,. (Could be one or 2 isolated wet microburst SEVERE's?). For nw NJ, if there is very little tonight then I could see isolated svr thunderstorms in ne PA drift into nw NJ and se NYS late in the afternoon or evening and then continue to LI as showers Friday night. Low prob of occurrence. SPC has no risk and wind fields are generally a little too light. 627P/6
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After yesterdays long range failure of convection (arrived Sunday night), must look ahead. Modeling, SPC, WPC graphics all suggest opportunity for heavy convection Wednesday-Thursday (22-23). Attached the 6 hr County Average threshold FFG, with hourly guidance even lower amounts. This shows vulnerability in parts of ne NJ and se NYS, plus urban paved environments. SPC Days 1-3 is attached as issued early Tuesday. Also, added a brief 06z/21 GFS snapshot of modeled winds aloft for LGA via Bob Hart's web page (time is in UTC). Note the near 30 kt or greater westerly flow at 500 and 300 MB, showing the idea of enough wind to foster development of SVR organization and strong downdrafts. In these two days, "isolated" storm totals of 4" easily possible with 'general' two-day total amounts of 1/2-2". Warm Air Advection (WAA) instability burst (KI popping into the upper 30s from southwest to northeast by daybreak Wednesday driven by a modeled small 850MB 30 kt jet core in central PA overnight) 'should' develop some briefly heavy showers or a thunderstorm for parts of our NYC forum early Wednesday morning, especially nw NJ/se NYS. After any clusters pass, cloud debris/instability pooling and surface wind shift convergence boundaries will probably be the determinants of when and where heavy convection occurs Wednesday afternoon through Thursday evening. Heaviest should be afternoon-early evening and per modeling, think the bulk of the FF/SVR should be along and north of I80 (far northern NJ, se NYS, CT and LI) but I defer to your assessments, and those of the NWS offices/SPC/WPC, and the modeling from the HRRR and SPC HREF. 734A/21