wdrag

Thanks much Don! Potent where it coalesces. Excellent info. Walt

Just missed our area too the southwest, but we're seeing 1/2-1" amounts in parts of the forum area of nw NJ this morning. A start. Am unsure whether more big storms develop late today (busted this morning's svr), but I think so... so far no svr/ffw (1130A) but CT LI might be favorable early-mid afternoon for iso SVR/FFW. Sun out in Wantage with 0.27" this morning - minor, normal summer showers with rolls of thunder on two separate occasions around 9A. Dewpoint here 78!! Dry air crossing apps now so we'll see where the boundaries show up at 3P. Will monitor til 120P, then out of touch for a while. See what we missed this morning... from the Reading Eagle! Reading 1 day day record for any August. Reading Regional Airport, the primary weather service site in Berks, was under the gun for several hours before and after dawn. The official site recorded 5.7 inches of rain, a record for the date and any date in the 151 Augusts in the precipitation database. At 9 a.m., other high measurements for Sunday included Riverview Park, 7.4 inches; Kutztown, 4.73; Newmanstown, 3.59; and Bernville, 3.53. -- you saw the wx underground data. I'll post more as time allows late today. Walt 1134A/2

Many 4-6" amounts near Kutztown PA early today. Here's a snapshot. 0.20 here in Wantage NJ since RB around 545A.

Adding in other multiple 5+, one 6" near Kutztown. DIX and OKX radars vastly udnerestimati\ng...axis excellent but amounts are well above their values. 828A/2

Good thread start: I forgot...just buried it in the 3 day due to Flooding. Below from the 709A/ tropical post. Please follow NHC, SPC, WPC, and local office discussion statements/watches/warnings. Plenty coming for our forum area. Whether they'll be significant for more than half our region, I don't know, but some spots will probably be bruised with SVR-Power outages, FF-brief detours. Not sure if anyone has observed what happened in se PA overnight. Near Reading and now approaching Allentown PA, widespread 2-4" rainfall... won't be surprised at 5". Not too much guidance was hinting at that but the WAA is the driver and will continue to be a player in todays weather. Today: RGEM/HRDPS best fit to what is going on now and what sort of expect in the future. SVR/FFW (1-3 issuance of each) anticipated between 8A-1P central/NNJ, se NYS arriving NYC near Noon. The risk probably shuts off for 3 hours early this afternoon in nw NJ/se NYC, but shifts across CT/LI this afternoon, especially CT. Meanwhile, am concerned NAM/HRRR are so paltry on redevelopment in e PA/w NJ 4-8P with weak front approaching from the west, into high CAPE air of near 3000J (HI near 100 in PHL) and pretty strong winds fields aloft for this time of year. IT IS POSSIBLE very little will redevelop late today, but I think unlikely. Had to take into account all dry modeling, but think sct SVR develop e PA 4P-6P, cross NJ/se NYS/CT 6P-11P. NYC/LI am less certain but risk. No promises on afternoon-evening and am less confident than yesterday, due to modeling, and so have to rely on pattern recognition. Rainfall under a few strong storms: 1" in 30 minutes but these are very narrow paths. Apparently biggest threat for heavy rainfall is between now and 1PM in NJ/NYC, se NYS. One additional note: Wind fields are quite strong and supercells not out of the question with a TOR possible somewhere in the forum.

Good Sunday morning everyone in our NYC forum, Please follow NHC, SPC, WPC, and local office discussion statements/watches/warnings. Plenty coming for our forum area. Whether they'll be significant for more than half our region, I don't know, but some spots will probably be bruised with SVR-Power outages, FF-brief detours the next 3 days. Not sure if anyone has observed what happened in se PA overnight. Near Reading and now approaching Allentown PA, widespread 2-4" rainfall... won't be surprised at 5"... and a SVR in progress at 635A. Not too much guidance was hinting at that but the WAA is the driver and will continue to be a player in todays weather. Today: RGEM/HRDPS best fit to what is going on now and what sort of expect in the future. SVR/FFW (1-3 issuance of each) anticipated between 8A-1P central/NNJ, se NYS arriving NYC near Noon. The risk probably shuts off for 3 hours early this afternoon in nw NJ/se NYC, but shifts across CT/LI this afternoon, especially CT. Meanwhile, am concerned NAM/HRRR are so paltry on redevelopment in e PA/w NJ 4-8P with weak front approaching from the west, into high CAPE air of near 3000J (HI near 100 in PHL) and pretty strong winds fields aloft for this time of year. IT IS POSSIBLE very little will redevelop late today, but I think unlikely. Had to take into account all dry modeling, but think sct SVR develop e PA 4P-6P, cross NJ/se NYS/CT 6P-11P. NYC/LI am less certain but risk. No promises on afternoon-evening and am less confident than yesterday, due to modeling, and so have to rely on pattern recognition. Rainfall under a few strong storms: 1" in 30 minutes but these are very narrow paths. Apparently biggest threat for heavy rainfall is between now and 1PM in NJ/NYC, se NYS. One additional note: Wind fields are quite strong and supercells not out of the question with a TOR possible somewhere in the forum. Monday after 4PM: refire convection in NJ and e PA and setting up for some sort of banded 4-8" rainfall Monday night 7P-Tuesday morning 7A. My guess is this band will be somewhere in e PA across extreme nw nw NJ into eastern NYS or w CT. For now my guesstimate is DXR-POU-across High Point NJ to near RDG?? It's not a classic PRE but am very sure there will be some sort of precursor event due to the nose of the 850MB jet favoring strong moisture transport northward into some sort of weak boundary/or mountainous driven lift zone. PWATS back up to 2", plenty of CAPE and winds might favor an embedded SVR, but I think the primary concern, wherever this set's up, is FF. Tuesday afternoon-evening: Isaias remains and associated heavy rainfall left of track and Gust 50kt eastern LI, maybe even all of CT. Storm totals between today-12z Wednesday... am thinking we see a few 7+ but I could be a little overdone, especially if banding doesn't develop as anticipated for Monday night, and/or Isaias track west of NJ. Added clustered 00z/2 guidance tracks for Isaias. 709A/2

Nt sure who're asking... but from my standpoint, FFW likely, even if for only 4 hours. BUT BUT BUT.. as good as this looks right now and has for several days... something always goes wrong. If I'm working, I'd probably want to be safely home by Noonish Tuesday and may not have to work on Wednesday due to the impacts-power outages and/or pockets of leftover flooding. Your 3-6 for the event sounds good... might end up just near 3? or quite a bit more, Take the near 3 as a good start. Storm goes w of you, then little chance of 3, more like just 1. WPC has you a good swath and the NAEFS looks big for NJ/NYC Hud Valley/far w CT. Lets see what happens.

Sorry, been out at family gatherings the past couple of days (distanced). Yes, I "think" this is going to be a multi episodic day in our NYC forum Sunday. 8A-1P n NJ se NYS maybe reaching NYC around Noon. I expect 1 to 3 SVR's and associated 1" 30 minute drenchers moving ne in WAA with diffluent 1000-500mb thickness and decent winds aloft. Then ~1 PM Sunday afternoon...ne PA/nw NJ and SE NYS shuts off, with potential for strong convection shifting only into a few spots of CT and central NJ. Thereafter, the trough approaching from the west , should activate a scattered-broken line of severe thunderstorms in remaining relatively high CAPE between 5P and midnight. First in e PA 5P-8P then possibly training SVR's or FFW in the I78-I195 corridor 8P-midnight. This based on a shot of drying midday moving into ne NJ/interior se NYS, then everything rejuicing late in the day-as it's recovered, and I think primed for release with the trough approaching. Need other input-guidance assessments but that's the way I see it. HI in PHL should rise to 100 tomorrow which tells me plenty of instability feeding in on the sw flow ahead of the trough. I think a PRE is likely Monday night from e PA into se NYS and w CT... i could be too far south on this and/or I could be totally mistaken that it occurs at aLL, but if occurs, 4-8" IN 6-12 HOURS and isolated svr within a fairly narrow swath. Again input from the experts on PRE sought. Isaias as you all see and think per NHC/local offices and AMWX. I have seen model guidance over 10" in in a small part of our area by 12z Wednesday. PRE"s and Tropical storm rains don't necessarily overlap... if they do, that's bad news (significant flooding in the overlap area which might be w CT?). The only other thing on Isaias... I'd like this to look more like a TS in its rain bands by the time it gets to NC. I think jet dynamics might straighten this storm out, which has not been very pretty so far- yet it has, as bad as it's looked, it's been fairly powerful. kind of an oddball storm which may mean it's odd all the way up the coast? In summary not much change from what I saw on the 00z/1 cycle. I have to take this one event at a time. Right now, let's see if SVR reports can be fairly widespread in our area by 1201AM Monday. Will reassess Sunday morning ~7A. 835P/1

Good Saturday morning everyone, Little change from what was posted yesterday and possibly my last post until Sunday morning.At that time, I may start a separate SVR topic for Sunday alone. Need more time to evaluate but SVR is likely for at least a few locations in our forum Sunday. On SVR: big CAPE of 3000J, HI near 100 PHL feeding the storms, decent wind aloft with only worry a little drop of the KI during the afternoon. Nevertheless, this could be a 2 or 3 SVR episode day. The first, northeastward moving storms during the morning with WAA, the second in the afternoon (still northeast moving), and the third a final trough passage line from west to east between 5 and 10PM. Eastern LI may be completely shut out of this. Primary threat region is far w CT-NYC all NJ se NYS and ne PA. Please follow local office and SPC guidance discussions. Thereafter a PRE is possible ~ a DCA-POU axis Monday night followed by squally excessive rain producing Isaias Tuesday afternoon-night. More details on possible impacts below. This does not include power outages but will add concerns on that tomorrow if still possible (SVR Sunday and Isaias squalls Tuesday) 1) Potential killer Rip Currents Monday-Wednesday for anyone who ventures into the waters s of LI. I'd be wary of swimming, especially non expert surfers/non expert swimmers. The significant undercurrent 1 feet 15 second swell may start arriving this weekend. These long period subtle swells surprise swimmers with their energy and are sneaky dangerous. The higher surf just preceding and following the storm (within 18 hours) usually scares off most swimmers. 2) Rainfall as per multiple ensembles and WPC guidance. My impression is that between 1AM Sunday and 1AM Wednesday, a few locations will see ~5-7" rainfall, with isolated (1 location) 10" amount not impossible. My guess is heaviest is NJ, se NYS, w CT... presuming track continues as modeled through 06z/1. To the right of Isaias, squally and less rain, possibly less than 1" total extreme eastern LI if Isaias tracks west of Montauk. 3) Per NHC 5AM Saturday 8/1 track: surge and wind field risks on the western side of ISAIAS are minimal but if the track shifts to where a portion of our area is on the eastern side of the TC, then those risks would significantly increase. I think eastern LI to the southeast New England coast are vulnerable for at least some of these stormier impacts. Preparation should continue for that...ie gusts 50 knot. 4) PRE: Composites posted yesterday. Where this PRE occurs, IF it occurs, is unknown but my best guess now is on an axis from vicinity DCA-POU Monday night based on 00z/1 modeling. Still could end up further north, again if it occurs. Not a CLASSIC PRE (need a little more se low level inflo than currently modeled) but hints are in the qpf modeling. Need to look a lot closer at guidance details and surface wind shift axis on Monday. Just too early to be sure of occurrence and if so, where. I'm thinking it will but I don't know where. These 6-12 hour events can be easy 4-8" producers in 6-12 hours. I'm looking for narrow slices of darker or even brightly colored heavier QPF in the modeling 12-24 hours in advance of Isaias in the GFS/EC/GGEM. If we get to 36 hours and it's still possible, then we shift to the NAM and HRRR SPC HREF. 636A/1

Hi..thanks for this! I agree BUT EC 12z run is drying out considerably during mid Sunday afternoon. So SVR may be limited to 10A-3P time frame. That's too early for my liking but wind fields/CAPE/KI support. Just wish the EC hadn't accelerated. Need to rereview tomorrow morning. Interesting summer weather action on the horizon..we seem to be in the slot for the Sunday morning event, A PRE close by Monday night and then the main show, whatever it is Tuesday. Timing a little uncertain but I think we're in a good spot for at least a portion of our forum. Saw NHC at 5P. Might be a little too dramatic but definitely squally potential. Thank you again. Walt 609P/31

Very good job way in advance nailing wetter than normal first week of August around here. Looks difficult to miss.

Failed forecast for the Max 3-4" range. Only verified about 2.5-2.75 in worst case, that I can find so far in a quick check. Think the rest did okay, timing, axis and glad LI got a pretty good rain. Note the DIX/OKX radar underestimated STP, imo, significantly per CoCoRAHS, RU CLIMATE stations and wx underground reports. Next events already in the other combined tropic. Should be an interesting few days ahead for some of us... water related. Northeast moving SVR a pretty big risk Sunday afternoon with stronger wind aloft, plenty of instability. This may show quite a few more damage reports than what we saw last night. Need to reevaluate with new guidance the next day or 2.

I worry when i put it out there, that some thing it WILL happen. Usually when i put it out there, I think odds are greater than 60% it will happen but have trapped myself too often with too strong a Categorical pontifications (near 100%). I do think we need to be aware of precursor rains, IF indeed Isaias does the coastal hugging as a TS. Bluewave posted on the UL jet anomaly which is a good idea of the potential contributions of the UL jet. Other on here noting the favorable upper air pattern (USA trough-WAR). Also for those using radar rains... I checked OKX and DIX estimates... they were too significantly too low in the east-west axis just below I78 last night. I its safe to say 3/4"-2.75" fell in that band last night (CoCoRAHS, WXUNDERGROUND and RU climate sites). It drains but soil remains a bit moist for whatever happens tomorrow night, then late Sunday svr risk, then the tropics, if its still on NHC track. Let's monitor and look for errors in the thinking. Not the end of the world but a player. Glad I'm not a cruise. 1119A/31

FFG is still high and River Flood ensembles are not amped. Still can see some problems develop if we get decent 1-3 total rains in NJ/se NYS Sunday and then followed by a coastal hugging Isaias track.

Good Friday morning everyone in our NYC forum, Little change from what was posted yesterday. Have used yesterdays as a starter with commented adjustments. It's likely we're going to see significant impact from Isaias. 1) Potential killer Rip Currents Monday-Wednesday for anyone who ventures into the waters s of LI. I'd be wary of swimming, especially non expert surfers/non expert swimmers. The significant undercurrent 1 feet 15 second swell may start arriving this weekend. These surprise swimmers with their energy and are sneaky dangerous. The higher surf just preceding and following the storm (within 18 hours) usually scares off most swimmers. 2) Rainfall as per multiple ensembles and WPC D4-5. Best multiple axis of 6-12 hr 4+ rainfall, to be determined. This on top of the amounts received Friday-Sunday will have to result in pockets of flooding. Where? Ensembles with the east turn (northern shutoff), now further north or non-existent implying less chance for OTS (i just learned that one yesterday). I'll add PRE info for comment in separate post but I think likely for a part of our NY forum Monday or Monday night, then it shifts north and northwest Tuesday as Isaias rolls northeastward. 3) Presuming the NHC 5AM Thursday track is reasonable, surge and wind field risks on the western side of ISAIAS are minimal but if the track shifts to where a portion of our area is on the eastern side of the TC, then those risks would significantly increase. I think eastern LI to the southeast New England coast are vulnerable for at least some of these stormier impacts. Not saying they will occur but my background preparation would include comments to that effect. 4) Isolated 7+" rainfall from the "necessary" combined events of Saturday nights WAA (warm frontal) event, Sunday afternoons probable fairly widespread severe storms, mainly nw NJ/se NYS westward into ne PA, and then finally either a PRE, or a direct impact of Isaias Monday-Tuesday. (maybe the slower 00z/31 EC is correct for early Wednesday but maintaining continuity with NHC). I'm more concerned today about a combined Predecessor Rainfall event and a possible direct ISAIAS impact in our forum. The 7+" rainfall in my estimation would probably have to occur west of the I95 corridor due to the ensembles probable combined Sat night-Sunday afternoon events depositing biggest amounts somewhere near the western edge of our forum coverage (~Sussex-Orange Counties?). If Sat night-Sunday does not occur (1-3" combined event band somewhere in that area), then a PRE or ISAIAS hit would have to do all the work by itself and at this time, this is too uncertain. So to get to 7+", it's a lot easier if we see sizable rainfall Sat night-Sunday. (There is still what I think is a diminishing chance not much happens here next Monday-Tuesday-it's in the envelope of possibilities). Let's see what happens. I'll be particularly interested in PRE comments. I'm adding PRE composites. Where this PRE occurs, IF it occurs, is unknown but my guess based on 00z/31 modeling is between I95 and Williamsport-Burlington Vermont. I'll add a link for the powerpoint. I'll also add modeling for the PRE which occurs in subtle convergence about 12-18 hours prior to the passage of the TC (usually east of the PRE so they don't necessarily overlap QPF events), and we need a decent RRQ of the UL jet (which is modeled to strengthen this coming week) and se inflow at 850MB, for a time. Plenty of PWAT and instability will be available. Looking for comments that this "possiblity" canNOT occur. I'm thinking it will but I don't know where. These 6-12 hour events can be easy 4-8" producers in 6-12 hours. I'm looking for narrow slices of darker or even brightly colored heavier QPF in the modeling 12-24 hours in advance of Isaias in the GFS/EC/GGEM. If we get to 36 hours and it's still possible, then we shift to the NAM and HRRR SPC HREF. I added EC ensemble 24 hr qpf simulation implied PRE in e PA/NJ well ahead of Isaias, and also the IR simulation. It's just a model and it can vanish in the future but this has my attention until it goes away. It's easy to say NO it wont happen but in these situations where it can be a flash flooder, we need to be alert for the possibility. 829A/31 https://www.wpc.ncep.noaa.gov/hmt/seminar_files/PRE_NWS_Teletraining.ppt

Good Friday morning, First glance a little disappointed in max rainfall. So far I find only 2.5" but need further eval. Anyone with more than 2.5" last night, please post. Thanks for adding all those comments on the overnight storms, and the radar imagery. Looks like the modeled R+ and potential SVR track was very good, especially HREF. Looks like general 1/2-2" in that slot, inclusive of LI I78-I195 corridor---definitely a little less than forecast but not all the reports are in yet. Added svr report info. More to post ~845A. 728A/31

Did anyone notice how HOT it may be/feel in NJ Monday if the slower EC is correct? Unsure of whether EC slowness on Isaias is correct? Posting more by 845A

Agreed100%. will update by 830A.

I think we're very close to seeing a rapid increase in convection and subsequent east-northeast development - training near I78. Winds turning nw and soon north, to the north of I78, while hot and humid upper 80s with TD low-mid 70s south of I78 (non marine). A good sign is the remaining pings of small but heavy showers the PA entering se NYS at 745P. In the meantime, not sure what will happen to all that DELMARVA activity, maybe it's own separate entity into the night? This may be pretty interesting between midnight -10AM in the southern part of our NYC forum area-at least for R+/TR+. (I78-LI southward). 750P/30 and possibly my last of the night.

Have seen .88" in ne Sussex County NJ near where digital STP is 1.8", which could have occurred in reality unless hail contaminated?

I think this will occur, big time. look for development between PHL-ABE* around 11-11P and toward NYC from there. All sorts of high dew point air moving northward from the Delmarva along with pressure falls. We've had two or three thunder episodes here. 215P, around 330 and about 520P. Dog barks when outside. Can't see what he hears. Wantage 0.07 so far. Added severe weather so far today in our area... the report in south central CT is a 47MPH wind gust at about 440P.

I'm staying off the EC for now (despite 2 of 3 similar runs the past 3 cycles), but do note a seeming trend to a more robust eastern seaboard-just off the coast solutions. Expert input sought... My guess is that despite cooling SST's as this storm moves north beyond NC, storm intensity may maintain due to pretty strong RRQ of the upper level jet and we should see an expansion of the tropical wind field. That's what I'm looking for. Let me know why this steady state intensity won't happen as the storm passes by LI. (how far east of?) Also: rains tonight, Sat night-Sunday afternoon-eve will be moistening up some of the areas with 3+" storms totals by daybreak Monday (i think). Then do we rely on ISAIAS direct left side heavy rain to douse us, or can ISAIAS pass by to the se of LI but a PRE occurs in the coastal plain with a big 6 hour dump Monday or Tuesday, 18 hrs before ISAIAS passes by?? The PRE is my interest... I still cant buy an eastern LI hit but updated ensembles the next several days can change my mind. For now, I'm hugging the NHC cone to embrace primary surge/wind/wave and primary ISAIAS rainfall. 450P/30

Just letting you know of near 40VIL developed just n part of Wantage NJ since 2PM... so far no warnings. Tha may not last too long. Haent had time to reevaluate but follow local statements and/or warnings. Thanks.

Quick update at 1053A: Too much cirrus today for much if any SVR... still need to monitor CT after 5P. However: Tonight seems destined for some warnings in NJ and possibly LI. FFW in the most vulnerable tracks of 3-4" within 6 hours and I still think 1 or 2 storms overnight with damaging wind and a possible super cell I78 southward. This latter supercell risk, I'll need to recheck at 4P. I've added 1 and 6 hr COUNTY wide threshold FFG for triggering a possible FFW, courtesy of NWS BGM. Do note that the NWS offices have sub basin triggers and can really hone in on specific areas, should the needed rainfall occur. You should be seeing-hearing lightning and dogs barking overnight in parts of NJ and LI with FFW potential late tonight-Friday morning primarily in any heavily paved communities where rainfall exceeds 3".I think that will be between I78-I195 in NJ and probably parts of LI.

Good Thursday morning, Decided to start a combined topic covering Saturday night, Sunday afternoon and the uncertain impact of ISAIAS this coming Monday-Tuesday. ISAIAS has track uncertainties until everything gets re-organized Friday. Thereafter, I think the EPS/GEFS should nail whether or not tropical storm conditions can impact the coasts. Follow NHC guidance and the contributions from American Weather tropical experts. One reason for uncertainty; I see multiple 00z/30 ensembles showing the northern bounds of heavy rainfall not too far north of our NYC forum which suggests, at this distant date, that a hard right turn of ISAIAS could yet occur that would spare us more than a dangerous rip current situation. In other words, we're on the gradient of substantial rainfall impact. Big forecast busts tend to occur in the ensemble gradients, buying in too early to one set of solutions or another. So dangerous rip currents are my first primary concern for Monday-Wednesday, especially Long Island. Southerly swells should gradually build over the western Atlantic into early next week. Presuming the NHC 5AM Thursday track is reasonable, surge and wind field risks on the western side of ISAIAS are minimal but if the track shifts to where a portion of our area is on the eastern side of the TC, then those risks would significantly increase. My secondary primary concern is isolated 7" rainfall from the necessary combined events of Saturday nights WAA (warm frontal) event, Sunday afternoons possible isolated severe nw NJ/se NYS westward into ne PA, and then finally either a PRE, or a direct impact of ISAIAS Monday-Tuesday. I'm more concerned about Predecessor Rainfall event rather than direct ISAIAS impact. The 7" rainfall in my estimation would probably have to occur west of the I95 corridor due to the ensembles probable combined Sat night-Sunday afternoon events depositing biggest amounts somewhere near the western edge of our forum coverage (~Sussex-Orange Counties?). If Sat night-Sunday does not occur (1-3" combined event band somewhere in that area), then a PRE or ISAIAS hit would have to do all the work by itself and at this time, this is far too uncertain. So to get to 7", it's a lot easier if we see sizable rainfall Sat night-Sunday. There is still a chance not much happens here next Monday-Tuesday-it's in the envelope of possibilities. (See the 06z/30 GFS run). Let's see what happens. I'll be particularly interested in PRE comments. 733A/30