wdrag

Cant promise colder but it seems the 850 temps cold be colder...if its a mixed environment or LE clouds or offshore storm passages, then the clouds keep the mins up. I kind of think this pattern has a killing freeze in it for the suburbs (1 night) but I could be overdoing it. It seems 850 temps and sfc temps in the Ohio Valley will be 5 to 10 below normal and I think that at least one day should be colder than any to date in NYC this Sept.

For the October discussion topic... Definitely colder or much colder than normal the first week per multiple models-ensembles. Additionally... 12z/22 ensembles suggest a slight covering of snow is possible either in the Catskills or Adirondacks sometime between Oct 4-6? I guess if that occurs that's not a good sign for our 20-21 winter being snowier than normal?

Smoke aloft coming fast across PA mid afternoon. Images of what it might look like for the bands 8P tonight, 8A Wednesday and 8A Thursday. NYC should see the back edge of this mornings band just to the east now, while cirrus from Teddy is along the CT River. So the 8A Thursday image suggests more smoke aloft for later Thu or Fri.

Did add to the 651A post (trajectory path from 00z/22 GFS ensemble). Not impossible for 2+ amount... but I don't see necessary long duration concentration, at least not yet. 803A/22

Wantage NJ Tue am: second consecutive frosty morning..this one more extensive than yesterday. Smoke aloft-albeit thin, is visible and will thicken from west to east late today before passing south of the NYC forum Wednesday...though it looks like a bit more to come toward the end of the workweek. Added one graphic for 2P this afternoon to show the approaching band. Ran some trajectories and not too excited about BETA contribution here, but added the forward trajectory from 500meters vicinity HOU beginning 00z/22 using the 00Z GFS ensemble. NAEFS has very low prob of >2" here by Oct 1, so it will rain and am hoping the WPC D7 totals are close... most or all of it between Sunday-Tuesday in possibly three primary bands (27-29). Will monitor NAEFS cold signal for the first week of October. This 00z/22 cycle has a high probability for colder than normal the first week of October. Hopefully many here noticed the smoke aloft yesterday, especially NYC longitude eastward. Was quite noticeable to my east forenoon Monday. 651A/22

Wantage NJ 629A: Frosty roofs etc and everyone should be noticing smoke in this mornings sunrise...not as dense as last week, but that's coming by Wednesday. Yesterday's predictive smoke post still reasonable.

Looks like smoke is coming back into the NYC forum... Not as thick for the next couple of days but probably a bit noticeable. HRRRX attached predictions for 8PM tonight, 8AM Monday and 8AM Tuesday. You can see it on the visible images over the midwest...but the initial revisit of smoke aloft arrives from southeast Canada tonight, then the midwest pall during mid week after theTeddy passage.

Will probably run some trajectories on BETA moist remnants by Tuesday the 22nd, to support possible moisture contribution to the large scale trough developing into the eastern USA around Monday the 28th. From what I can tell, the initial BETA contribution will be swept eastward, well to our south this coming Friday-Saturday,. Thereafter, it appears to me some of that remnant moisture will be drawn northward along the east coast. NAEFS now onto a potentially meaningful rain event (nne-ssw bands) for early next week (28-29). We'll see if se NYS and extreme nw NJ benefit from this. No rain here since the 10th. 808A/20

Looks like we here in Wantage NJ are in the midst of at least a 14 dry spell having started early on the 11th with the xext chance of measurable rain here around the 24th-25th and per the NAEFS, nothing significant through Oct 2. Good thing days are shorter and overall it's much cooler, so remaining flowers not nipped by frost here in the I84 corridor valleys (Sat-Tue mornings), won't need as much watering. Might??? become interesting for small scale fires around here if this keeps up...especially se NYS (added graphic qpf % departure last 2 weeks and then am mentally projecting ahead next 1-3 weeks). West Coast smoke overhead along I95 corridor through the I84 corridor today sinks southward so that by tonight we should be pretty much cleaned out as it sinks into the southeast USA. Finally, while the NAEFS was indeed too far too north for early today, it and the UKMET (past two cycles) especially picked up on a secondary area of relatively heavy qpf that occurred this morning on the north shore of LI (Suffolk County especially) with 0.5 to .85" amounts are noted in WU data and on the digital radar precip estimates. Overall however, I think the GFS did best on northern extent of qpf throughout the prior week of forecast cycles. 656A/18

Regarding the attached graphics (01z/12): Birds on radar or not… Need to check loops of reflectivity, the VAD wind profile versus modeled wind below 3000 feet for nighttime migration, and preponderance of 20 DBZ reflectivity near roosting areas (example along lakes). Also against bird migration prediction-example attached graphic. To see the birds in the morning, you'll need to see concentric rings take off during the morning. But this was a nighttime radar image. I and others typically referenced these radar clutter's as AP. I don't think it's clear that this was caused by bird migration although the fall bird migration period begins about this time. I may have more confirmatory information, one way or the other in a few days. What you can assume from most of the radars, is a mix of clutter, dust, insects, and possibly birds near the radar. The velocity measures dust/moisture etc at the intersected elevation. Here is a link... examples are provided.https://www.weather.gov/iln/birds. I've referenced a peer reviewed paper in the the AMS Journal Weather and Forecasting. HTTPS://JOURNALS.AMETSOC.ORG/WAF/ARTICLE/13/2/453/38044/DISPLAYS-OF-BIRD-MOVEMENTS-ON-THE-WSR-88D-PATTERNS RESEARCH ARTICLE| 1 JUNE 1998 Displays of Bird Movements on the WSR-88D: Patterns and Quantification* Sidney A. Gauthreaux, Jr.; Carroll G. Belser Wea. Forecasting (1998) 13 (2): 453–464. https://doi.org/10.1175/1520-0434(1998)013<0453:DOBMOT>2.0.CO;2 Article history Abstract The WSR-88D can readily detect birds in the atmosphere in both clear air and precipitation mode, and echo reflectivities of 30–35 dBZ may be realized during heavy migration events or when birds are departing a roosting site. This paper describes the appearance of birds on base reflectivity, base velocity, and velocity azimuth display wind profile products, and presents a calibration curve that relates decibel values of reflectivity to bird migration traffic rates. The recognition of bird displays in WSR-88D products is essential for the accurate interpretation of data gathered by the radar and its use in the development of forecasts. The findings also document the importance of the WSR-88D as a remote sensing tool for biological studies of birds and insects in the atmosphere and the application of such information in the avoidance of bird–aircraft collisions. It is clear that migrating birds are biasing the winds aloft information generated by the WSR-88D VAD algorithms. The birds so influence the VAD wind profiles that they often can be used to document the altitudinal distribution of the migration (see Haro and Gauthreaux 1997; Gauthreaux et al. 1998) 4. Bird roosting movements on the WSR-88D Outside of the spring and fall migration seasons the WSR-88D readily detects concentrations of birds (and bats) as they depart and return to roost sites. The departures of birds from roost sites at dawn and near sunrise are particularly prominent on base reflectivity products as the radar beam is often bent back toward the ground because of superrefraction. Inversions of temperature and moisture influence the index of refraction of the radar beam in the atmosphere, and these conditions are characteristic of the lower atmosphere near dawn when the birds depart their overnight roost (Russell and Gauthreaux 1998). In contrast, near the time of sunset and dusk normal propagation of the radar beam usually occurs, and the beam is often too high to detect the bird targets returning to the roost unless they are flying at altitudes covered by the radar beam. Because dense swarms of insects in the atmosphere produce base reflectivity displays that are quite similar to low-density bird migration displays (see Russell and Wilson 1996), it is essential that base velocity information be gathered at the same time as base reflectivity products. With a knowledge of the winds aloft it is possible to distinguish bird movements from insect movements, because the latter have air speeds that rarely, if ever, exceed 8–10 m s−1 (most are between 4 and 6 m s−1) while migrating birds typically fly at speeds greater than 10 m s−1. Because of their low air speeds insects tend to move with the wind, deviating just a few degrees from down wind, whereas birds will sometimes fly against the wind. In general, insect ground speeds exceed corresponding wind speeds by approximately 2–6 m s−1 (Schaefer 1976). The recognition of migrating birds on weather surveillance radar will also clarify many of the misconceptions that television weathermen have about “noisy” or “anomalous” radar patterns that appear on national mosaics. These mosaics usually display reflectivity levels of 20 dBZ and above, because the lower reflectivity levels have been eliminated or filtered out. Despite setting the minimum base reflectivity filters at 20 dBZ, during dense bird migrations, reflectivity values from the mass of migratory birds may reach 20 dBZ levels and even reach 30-dBZ level during the seasonal peak of migration. Such patterns are commonplace at night during the spring and fall migration periods. 918A/16 1113A added migration news from 9/10-11... was Low-medium in the northeast.

Good Wednesday morning all, The NAEFS may have been very wrong in it's northward extent of rainfall expectations Friday, with the GFS projecting to be best on this (so far). However, the SPC HREF is trying to develop showers along the I95 corridor late Thursday (mid level FGEN) so we're not quite done with a rain chance NJ-LI-S CT. In the meantime, a post included that I've sent to my family-friends on Smoke projections. Continuing the previous theme on West Coast smoke seen in the northeast this Wednesday morning Sept 16. It appears somewhat thinner today. Yet, it may be with us into Friday, but modeled to be less noticeable. High clouds may be arriving this evening but pass above the smoke layer that is generally located between 5000 and 18000 feet aloft. The clouds should be above 20000 feet. Lower clouds (and eventually showers?) will complicate smoke visuals Thursday and Friday. I've added a couple of model forecast smoke graphics. It may be of interest that we get a hint of smelling smoke late Thursday or Thursday night here in parts of the northeast, particularly terrain above 1000 feet elevation. Attached are graphics showing 1) entire smoke plume at 2PM Thursday, then near surface smoke expectations Thursday afternoon at 2PM and Thursday night just after midnight (second and third graphics below from the United States HRRRX model). The last graphic is from a Canadian smoke model. You can see some advance into the northeast. So we'll see how that goes. 846A/16

Reviewing week two outlook as suggested by the NAEFS week 2 guidance posted 8/30. Have added the QPF for week two... (only 1 event the 9th-11th with the second Sun-Mon 13th-14th being a null event)), and the week two national average temp which showed the trough axis was actually further west than implied ~Aug 30. Still the guidance was good at opening up east coast possibilities of more normal rainfall and central USA cooler than normal.

12z NAEFS is hardening the northern fringe of qpf in our NYC forum, despite most models less than 0.1". 12z GEFS/EPS both have 0.1" to central NJ - s coast of LI..the EPS about 12 hours slower than the fast 12z/15 GEFS. The NAEFS 52 member ensemble must have a high bias in some of it's members (plenty of variability is color coded) but has the 0.4" qpf on successive cycles thru NNJ to the N of LI. I know many on this forum do not think much of the GGEM. I do think it's good and to enjoy a cyclonic precip event (non-convective), the GGEM must be on board- I've very seldom seen the GGEM dry and an event occur (lets say within 72 hours). So, for the sake of a conservative approach...we'll expect the NAEFS to be wrong. Just the same I'm posting the 00z/12z cycles 24 hr qpf ending 8PM Friday and we'll see if it had any idea of the northern fringe qpf.

Good Tuesday morning everyone: Sally fringe rain, closest pass may be delayed til Fri night-Saturday? and most 00z/15 models cut the northern fringe below our NYC area forum. However, NAEFS/EPS still give us a chance though with a slight southward trend since yesterday at this time. SMOKE: That I think is our primary visual interest the next 3 days. No change form the HRRR modeled heavy concentrations graphics posted last evening, near 15000 feet today. Have added the 1000 ft concentration for 06z/Thursday, implying a small concentration of the smoke may be getting closer to ground level in parts of the northeast during Thursday? Also added the vertical concentration for that time, which keeps us in the smoke plume, probably through the day Thursday. Finally, a cross section, for 06z Thursday near NYC, showing that most of the smoke is above 5000 feet. NAEFS (no image due to D10 uncertainty) vicinity the 25th: appears a bit QPF active off the east coast. 653A/15

Just a model idea of how thick the smoke may be overhead tomorrow at 12z and 21z/15. Also a cross section of how it should remain at least above 5000 feet late tomorrow, tho descending closer to ground level as we go into Wednesday (modeled data not shown).

Again, for those that are interested. Nothing circular in that radar presentation... this is classic AP. A loop of the radar would show a migration if any ... very highly doubt birds. Instead insects, moisture discontinuities with inversions developing and hills intercepted. I did check with a retired NWS specialist.

Difficult for me to easily explain in lay persons language. Temp/dew of 35/32 should yield a wet bulb of about 33, cold enough to snow. Need that wet bulb at or below about 33.5F to have a chance of snow in a non convective situation. Dewpoint is the commonly referred indicator of discomfort (or lack of) in warm season. Wet Bulb Temperature - Twb The Wet Bulb temperature is the temperature of adiabatic saturation. This is the temperature indicated by a moistened thermometer bulb exposed to the air flow. Wet Bulb temperature can be measured by using a thermometer with the bulb wrapped in wet muslin. The adiabatic evaporation of water from the thermometer and the cooling effect is indicated by a "wet bulb temperature" lower than the "dry bulb temperature" in the air. The rate of evaporation from the wet bandage on the bulb, and the temperature difference between the dry bulb and wet bulb, depends on the humidity of the air. The evaporation is reduced when the air contains more water vapor. The wet bulb temperature is always lower than the dry bulb temperature but will be identical with 100% relative humidity (the air is at the saturation line). Combining the dry bulb and wet bulb temperature in a psychrometric diagram or Mollier chart, gives the state of the humid air. Lines of constant wet bulb temperatures run diagonally from the upper left to the lower right in the Psychrometric Chart. Dew Point Temperature - Tdp The Dew Point is the temperature at which water vapor starts to condense out of the air, the temperature at which air becomes completely saturated. Above this temperature the moisture will stay in the air. If the dew-point temperature is close to the air temperature, the relative humidity is high, and if the dew point is well below the air temperature, the relative humidity is low. If moisture condensates on a cold bottle from the refrigerator, the dew-point temperature of the air is above the temperature in the refrigerator. The Dew Point temperature can be measured by filling a metal can with water and ice cubes. Stir by a thermometer and watch the outside of the can. When the vapor in the air starts to condensate on the outside of the can, the temperature on the thermometer is pretty close to the dew point of the actual air. The Dew Point is given by the saturation line in the psychrometric chart.

Adding on to the coming cooler trend expressed above in Bluewave post...NAEFS D8-14 (Sept 22-29)attached pretty much is cooling us a little a closer to the monthly normal from the above normal first two weeks of Sept.

Good Monday morning everyone, Sally should pass out to sea well south of our area, per NWS guidance as added below. The only major model uncertainty is the CMC ensemble which biases the NAEFS rather wet up here with southerly flow 850MB moisture contribution and potential mid-level FGEN. Ensemble guidance of 00z/14 EPS/GEFS is also wetter than the 00z/14 operational cycle and seems to have trended slightly north from yesterdays post of 00z/13. The NAEFS prob for 2" axis is directed into the northeast USA for Thu night-Friday. So, this is posted not to say Sally will impact our area with moisture contribution but forecaster's considerations that may need blending higher? QPF is yes/no. In this case, operational modeling says much more strongly NO, but ensembles suggest another look see is required. Monitor the future trends to see if a somewhat wetter scenario will develop for the I95 corridor of the NYC forum late this workweek. It's basically our only hope for substantive qpf between the event of this past Wed night-friday morning (9th-11th) and Tuesday Sept 22nd. 648A/14

On Sally: not starting a topic until I see a decent chance of 2+" of rain in our forum(would have to be southeast edge) or resultant pressure gradient creating gale-tropical northeast wind gusts. Right now the NAEFS prob for 2" is less than 20%. Most of the guidance is a potential grazer contributing impact for the southern edge of our NYC forum. So yes, Sally might contribute-enhance potential for a brief nor'easter?? but I don't think it's worth a topic at this point due to likelihood of main hazard risk being only for marine (gale gusts s&e of LI?). You're welcome to start a topic-just doesn't look abnormal to me (at least for rain, and should not be much, if any, player in se NYS which missed a lot of this past Thursday's rain). Graphics: Added 00z/13 EPS, 06z GEFS 24 hr rainfall ending 00z/Sat, and 00z EPS Sally tracks, plus 24 hr NAEFS rainfall for Wed, Thu, Fri-just check the legends. Isohyets In MM, so 10 MM, is about 4 tenths of an inch. Variability of ensemble rainfall is color coded in the legends. Basically this post is in agreement with WPC D1-7 QPF from earlier this morning. 753A/13

I don 't think so. Not likely after sundown... and the best way to see is a loop where you can see them moving, best time tends to be near sunrise.

So it's trending closer for late Thursday or Friday. Added 12z GEFS/EPS tracks which are decidedly closer than the 820AM post. Also NAEFS 52 member mean which offers us on the northern fringe of near 1/2" (10MM). NAEFS probs for 2" are not in yet. Fast moving but a possibility of rainfall enhancement Friday, if it doesn't pass too far south. For now, the trends in the past 12 hours are slightly more favorable.

Problem solved... color coding can be the confusion in high gradient pockets... it will not jump from 0.5 to 2.5" without color coded intervening ranges. It's agreed that this image is about as good as it can get. Accuracy will improve in the future years.

Regarding the probable development of (TD19 as of 12z/12) Sally in GOMEX. Has a currently UNLIKELY but small chance of contributing moisture ahead of an approaching cold front moving into our area late this coming week (Thu-Fri 17th-18th?) Here's the 00z/12 EPS... 00z/12 GEFS does not have it for us (furthest north is dark brown track), but a few from the EC ensemble attempt a newd drift toward PA. No topic planned for this for at least another day or two, to monitor overall 500MB pattern. 821A/12