Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/16/18


Area Forecast Discussion
National Weather Service Charleston SC
1023 PM EDT Mon Oct 15 2018 .SYNOPSIS... Summer-like pattern with above normal temperatures will prevail until a cold front crosses the region Wednesday into Wednesday night. Cooler high pressure will then move in through late week before a stronger cold front likely pushes through Saturday night. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... As of 1015 PM: KCLX detected a few weak showers drifting east over the central Savannah River Valley. The latest run of the HRRR indicates that the showers will slowly fade as they track east. Sfc observations and satellite indicates that no fog has developed across the forecast area so far this evening. However, give dewpoint depressions and latest MOS, I would expected at least isolated fog to develop by midnight. As of 735 PM: The going forecast appears on track. As of 625 PM: Weak coastal showers have generally dissipated along the southern SC coast. KCLX indicates a well defined sea breeze from Bulloch north to Allendale County, advancing inland. The dewpoints in the wake of the sea breeze should increase into the low to mid 70s tonight. Given the rising dewpoints, thinning cloud cover, and light winds, fog should begin to develop late this evening. Fog late tonight may become locally dense. Previous Discussion: Isolated showers extending from the Tybee Island/Hilton Head area north along the I-95 corridor to start will dissipate by early evening. Then, low-level flow veering toward the SW overnight should hold additional isolated/scattered showers over coastal waters and just offshore of coastal counties. Overnight, the combination of elevated dewpoints, light surface winds and relatively dry air aloft should combine to support fog/stratus. The latest forecast indicates patchy fog developing around midnight then expanding to areas of fog late tonight/toward daybreak Tuesday. Fog could become locally dense. However, W/SW winds increasing to 15-20 knots just off the surface later tonight could promote sufficient mixing to prevent a widespread/dense fog event. Also of note, the latest forecast holds significant fog just off the immediate coast. However, low-level winds could push inland fog/stratus toward the coast late. Will continue to assess tonight. Otherwise, unseasonably warm temps will only bottom out around 70F inland and in the mid 70s at the coast. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... After some morning fog Tuesday we expect unseasonably warm temperatures into Wednesday ahead of an approaching cold front which should push through from northwest to southeast Wednesday into Wednesday night. A few showers and thunderstorms are expected Tuesday/Tuesday night, mainly inland, then across most of the forecast area Wednesday into Wednesday night as the front pushes through. Not much rainfall is expected overall and the chance of severe storms is very low. Much cooler and drier conditions are then expected Thursday, although can`t completely rule out a few showers near the central GA coast where some moisture convergence is likely due to the increased northeast winds. Temperatures will remain above normal through Wednesday for most if not all of the forecast area, with the northwest tier toward the Pee Dee/Midlands/CSRA the only area that could see below normal temps depending on the frontal passage timing and associated rain/cloud coverage. Below normal temperatures on likely Thursday with highs only ranging from near 70 close to the Pee Dee/Midlands to mid 70s generally south of I-16. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... By Friday, the center of surface high pressure is expected to shift offshore as another low pressure system moves east near northern Ontario with an associated cold front draped across portions of the northern U.S. Model guidance continues to show this front moving with purpose, crossing the Appalachians by Saturday and moving through the forecast area by Sunday morning. Other than southernmost zones where better moisture persists, a dry forecast will be advertised heading into the weekend, with precipitation chances increasing Saturday and Sunday with the front. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... KCLX indicates a well defined sea breeze from Bulloch north to Allendale County, advancing inland. The dewpoints in the wake of the sea breeze should increase into the low to mid 70s tonight. Given the rising dewpoints, thinning cloud cover, and light winds, fog should begin to develop at the terminals late this evening. The TAFs will continue to feature MVFR vis for fog between 8Z-13Z. Extended Aviation Outlook: VFR will prevail through Saturday at KCHS/KSAV. Brief ceiling/vsby restrictions possible from morning low clouds/fog. Some showers and/or weak thunderstorms also possible, mainly during the afternoon Tue and again Wed/Wed night. && .MARINE... Tonight: S/SE winds around 10 kt will turn toward the S/SW later tonight. Seas will remain 2-3 ft. Tuesday through Saturday: A cold front will move through the waters Wed/Wed night from north to south with increasing winds/waves after that, likely reaching Advisory levels for all waters into Thu night/early Fri. Conditions could go back downhill Saturday as a cold front approaches and possibly moves into the waters later in the day. && .CLIMATE... Record high maximum and record high minimum temperatures will be challenged until midweek. We have listed records that fall within 2-3 degrees of forecast values. Date Location Record High Record High Minimum Mon 10/15 CHS 87 (1985- already tied) CXM - 75 (1925) Tue 10/16 CHS 87 (1942) 71 (1985) CXM 87 (1925) 73 (1933) SAV 90 (1941) - Wed 10/17 CHS - 70 (1999) SAV 91 (1921) - && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...NED/SPR SHORT TERM...RJB LONG TERM... AVIATION...NED/RJB MARINE...RJB/SPR CLIMATE...
Area Forecast Discussion
National Weather Service Dodge City KS
623 PM CDT Mon Oct 15 2018 ...Updated aviation discussion... .SHORT TERM...(This evening through Tuesday) Issued at 1215 PM CDT Mon Oct 15 2018 Despite a persistent strong southwest flow aloft, dry conditions will continue through Tuesday afternoon as a prevailing west to northwest downslope flow near the surface reinforces a much drier air mass across western Kansas. Near to below freezing temperatures are expected tonight even as the aforementioned west to northwest downslope flow draws slightly warmer air at H85 into the region. The question will be whether temperatures drop low enough to warrant a Hard Freeze Warning for those areas failing to drop below 29F this morning, specifically zones along the Oklahoma border and portions of south central Kansas. Under mostly clear skies, the HRRR and HiResW-ARW suggest lows generally down into the upper 20s(F) to the lower 30s(F) overnight regardless of downslope westerlies. However, fairly light winds and the clear skies may allow for lower temperatures in lower lying areas. Will have to keep possible headlines in mind later this afternoon for any hard freeze potential late tonight for the areas mentioned above. A modest warming trend will continue into Tuesday with highs well up into the mid/upper 50s(F) to the lower 60s(F). .LONG TERM...(Tuesday night through Monday) Issued at 100 PM CDT Mon Oct 15 2018 Precip chances remain absent across western Kansas Wednesday as surface high pressure is slow to push eastward, only giving way to a southeasterly upslope flow by Wednesday night. Chances pick up a little Thursday as a closed upper low in the deep Desert Southwest begins to lift northeast into the Four Corners Region creating an increasingly difluent and strengthening southwest flow aloft across the Western High Plains. Meanwhile, a prevailing southeasterly upslope flow will slowly draw low level moisture back into central and much of southwest Kansas, but will do very little to increase instability. Still, enough lift will be present to support the potential for possible light rain development across portions of southwest and central Kansas with minimal rainfall amounts expected. Otherwise, the drier pattern resumes through the weekend as yet another frontal boundary is projected to push through western Kansas Friday bringing another shot of dry air into the Western High Plains. Temperatures are expected to remain a little below normal Wednesday as a broad surface high is slow to shift eastward across the Central Plains, allowing for little erosion of the cooler air mass across the high plains. Should see highs only up into the mid/upper 50s(F) again Wednesday afternoon with a few lower 60s(F) possible further southeast. Similar highs are expected Thursday before a weak cold front pushing through Friday helps keep high temperatures near to below seasonal through the early part of the weekend. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 622 PM CDT Mon Oct 15 2018 Weak high pressure aloft along with high pressure at the surface will keep skies clear and winds light and variable through this period. && .PRELIMINARY POINT TEMPS/POPS... DDC 28 60 37 61 / 0 0 0 0 GCK 27 58 33 58 / 0 0 0 0 EHA 33 58 37 56 / 0 0 0 0 LBL 28 60 37 59 / 0 0 0 0 HYS 25 60 37 59 / 0 0 0 0 P28 28 62 40 63 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... Hard Freeze Warning from 1 AM to 9 AM CDT Tuesday for KSZ080-081- 087>090. && $$ SHORT TERM...JJohnson LONG TERM...JJohnson AVIATION...Gerard
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
921 PM CDT Mon Oct 15 2018 .UPDATE... While the ongoing forecast is in good shape minor tweaks were made to the QPF, PoP, and weather grids to reflect ongoing radar trends and to align the forecast with what the high resolution models show for the rest of the night. A flash flood situation has developed across the Hill Country through the evening as 1 to 3 inches of rain have fallen over the last 6 hours, bringing the daily total across much of Llano, Gillespie, and parts of Burnet county up to 5 to 6 inches. While this rain has fallen over several hours the ground is so saturated from recent rains that anything that falls is turning into runoff resulting in Flash Flooding across these areas. Reports from county EMs and sheriffs offices in Llano and Gillespie county show that multiple roads are closed across both counties due to water over the roadways. This include roads that typically do not flood or are not considered low water crossings. The message tonight across the Hill Country is that if you don`t have to get out and travel, stay home. Flooded roadways at night are difficult to detect, and with such widespread flooding and multiple roads closed being out and about across these areas tonight is dangerous. Over the next several hours the HRRR, Texas Tech WRF, and other high resolution models show rainfall moderate rain continuing to move northeast over the Edwards Plateau and Hill Country before lifting northward out of the area Tuesday morning. Because of the saturated soils this has become less about intense rainfall rates, and more about longer duration rains resulting in runoff and flooding. Flash and River Flooding will continue to be a possibility through the night from Edwards through Kerr, Gillespie, up to Llano and Burnet Counties. Area rivers have also responded to the rainfall with parts of the Nueces, Guadalupe, and Llano Rivers all above flood stage tonight. To those along and east of I-35 isolated to scattered light rain will be possible through the overnight hours with lows dropping into the mid to upper 40s. && .PREV DISCUSSION... /ISSUED 714 PM CDT Mon Oct 15 2018/ AVIATION... Periods of SHRA are expected at the terminals through at least 14-18Z Tuesday as an upper level speed maxima overrides a frontal boundary located around 850 MB draped north of the terminals. This will result in visibilities dropping as low as LIFR in heavier SHRA, with IFR/MVFR conditions prevailing as ceilings remain trapped beneath a low level frontal inversion. With the surface pressure gradient relaxing, expect northerly winds to begin decreasing but remain generally elevated in the 10-15 knot range. Amendments are expected to handle more intense SHRA that approach the terminals. PREV DISCUSSION... /ISSUED 410 PM CDT Mon Oct 15 2018/ SHORT TERM (Tonight through Tuesday Night)... Much cooler temperatures along with widespread rain and a few thunderstorms can be found across south central Texas this afternoon. Temperatures are currently in the upper 30s to upper 40s across the region, compared to 24 hours ago when temperatures were mainly in the 80s to lower 90s. Widespread rain along with a few embedded thunderstorms are expected to continue through tonight as southerly warm air advection above the cold low-level northerly flow continues. For the early part of this evening, the main concern is expected to remain out west along the Rio Grande, where the HRRR suggests some stronger convection from Mexico will move northward into the Rio Grande plains. For the overnight hours, the models suggest additional showers and embedded thunderstorms will continue, with the heavier totals expected to remain across the Rio Grande plains, southern Edwards Plateau and Hill Country. Locally heavy rainfall may also spill over into Tuesday and with this in mind, we have opted to extend the Flash Flood Watch into early Tuesday evening. Storm total amounts through Tuesday of 1 to 3 inches with a few totals of 4 to 6 inches are expected. LONG TERM (Wednesday through Monday)... We could see a brief break in the rainfall on Wednesday for areas along and east of I-35. However, west of I-35, rain chances continue to remain high as additional shortwave energy moves out of Mexico into the Rio Grande plains. Rain chances look to increase again on Thursday as the medium range models show a series of disturbances moving up from deep south Texas into the region. The forecast for the upcoming weekend into early next week remains uncertain as the operational GFS and ECMWF diverge on the mid-level flow pattern. The GFS suggests a drier forecast with a surge of cool and dry air on Saturday. The ECMWF also shows this surge of cooler air, but maintains a warm air advection pattern and keeps much higher rain chances intact. For now, we will keep rain chances in the forecast, but have gone a little lower than the ECMWF. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 46 44 47 45 54 / 100 90 80 50 40 Austin Bergstrom Intl Airport 47 46 47 43 55 / 100 90 80 50 40 New Braunfels Muni Airport 48 45 49 45 56 / 100 90 70 40 30 Burnet Muni Airport 43 41 44 43 53 / 100 100 80 60 50 Del Rio Intl Airport 47 43 48 46 54 / 70 90 70 70 70 Georgetown Muni Airport 45 43 46 45 53 / 100 90 80 50 40 Hondo Muni Airport 50 44 50 48 57 / 100 90 70 50 40 San Marcos Muni Airport 46 44 48 46 55 / 100 90 70 40 30 La Grange - Fayette Regional 51 47 50 49 58 / 80 80 60 30 30 San Antonio Intl Airport 48 45 49 46 57 / 100 90 70 40 40 Stinson Muni Airport 53 47 52 48 58 / 100 90 70 40 30 && .EWX WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch through Tuesday evening for Bandera-Blanco-Burnet- Edwards-Gillespie-Kendall-Kerr-Kinney-Llano-Maverick-Medina-Real- Uvalde-Val Verde-Zavala. && $$ Aviation...Huffman Short-Term/Long-Term...Treadway
Area Forecast Discussion
National Weather Service Marquette MI
756 PM EDT Mon Oct 15 2018 .SHORT TERM...(This evening through Tuesday) Issued at 357 PM EDT MON OCT 15 2018 Water vapor imagery and RAP analysis show a vigorous shortwave moving across the Upper Lakes. Wave gave a nice boost to shsn across the area this morning into the mid aftn as it moved across the area. Another month or so down the road, and this type of system would have produced hvy lake enhanced snow. Now, with subsidence spreading over the area behind the shortwave and with the negative impact of a still relatively high fall sun angle, -shsn have diminished to isold/sct coverage over the w despite 850mb temps around -9C. Diminishing trend has also taken hold over the e recently. Otherwise, it`s been another chilly day under mostly cloudy skies. Temps are mostly in the 30s. Upstream, next shortwave of interest is already diving se thru Saskatchewan/Manitoba. The next shortwave will dive se into the Upper Lakes by Tue morning. In response to this wave, waa will begin with low-level winds backing to the sw tonight. This will bring an end to ongoing light lake effect pcpn from w to e this evening. With a decent shot of isentropic ascent noted on the 290k sfc (roughly 700-750mb), might be able to generate a little -sn over the nw tonight, and then late tonight over the e where low-level winds may back just enough to help bring some shallow moisture off Lake MI. Cold front will then sweep across the area during the day Tue. CAA is not especially strong with 850mb temps dropping from around -2C in the morning to -5 to -7C by 00z. With water temps roughly -6 to 8C, conditions will be marginal for lake effect pcpn, especially with the negative effect of daytime heating. Cyclonic flow will be helpful, but overall not expecting anything more than isold/sct coverage of lake effect showers, not too different from what is currently occurring. Will be a blustery day with winds gusting 20-30mph... up to 35mph or so on the Keweenaw. Expect high temps in the upper 30s in the higher terrain nw to the mid 40s s central and e. .LONG TERM...(Tuesday night through Monday) Issued at 242 PM EDT MON OCT 15 2018 Upper air pattern consists of a 500 mb closed low over the desert sw and a deep trough across the eastern half of the U.S. with a ridge in the sern U.S. and in the Pacific NW 00z Wed. Upper air pattern changes little 00z Fri except that the ridge in the sern U.S. retrogrades a bit to the Gulf Coast. Typical northwest wind flow lake effect pcpn pops will continue through Wed night, then Thu looks dry and temperatures get to near normal. Did not make too many changes to the going forecast overall. In the extended, the GFS and ECMWF show a 500 mb trough in the northern plains and central Rockies down into the desert sw with a ridge over the wrn U.S. 12z Fri. A cold front will be moving through the area on Fri with 850 mb temperatures dropping down to -6C to -9C over Lake Superior 12z Sat as a deep 500 mb trough moves into the upper Great Lakes. This trough moves off into the lower Great Lakes 12z Sun. A shortwave ridge moves into the Rockies 12z Mon with a deep and broad trough across ern N.A. and another shortwave moving into the upper Great Lakes on Mon. Temperatures look to stay below normal for this forecast period and will have lake effect pcpn for most of this forecast period. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 730 PM EDT MON OCT 15 2018 Although there is a break in the cloud cover this evening at the terminals, more clouds are on the way. This next batch should keep ceilings in the VFR category overnight, but could easily teeter into MVFR, especially closer toward daybreak. Additionally, some more showers could develop overnight into tomorrow, with KCMX having the higher chances of seeing a temporary reduction in ceilings and visbys tonight. Look for more lake effect/enhanced shower activity at all three terminals during the day tomorrow. Winds currently out of the W-SW will initially become more southwesterly this evening before veering westerly. These westerly winds will be breezy/gusty during the day tomorrow. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 357 PM EDT MON OCT 15 2018 Typical fall pattern will affect Lake Superior during this week with windy conditions dominating. A few periods of gales are expected. There will be some w to nw gale force gusts over eastern Lake Superior this evening, but a more solid period of gales will develop over western Lake Superior tonight under strengthening sw winds ahead of the next disturbance dropping toward the Upper Lakes. As winds veer w to nw on Tue, gales will transition to eastern Lake Superior though some gale gusts may continue over portions of western Lake Superior. Winds of 20-30kt will then generally prevail Tue night/Wed. A brief period of lighter winds will follow Wed night as a high pres ridge passes. Next period of gales will arrive Thu aftn/night as another disturbance drops toward the Upper Lakes. Winds will mostly be in the 20-30kt range Fri/Sat, but not out of the question that a period of gales will occur at least over eastern Lake Superior during this time. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... None. Lake Superior... Gale Warning from 2 PM Tuesday to midnight EDT Tuesday night for LSZ265>267. Gale Warning from 11 PM EDT /10 PM CDT/ this evening to 8 AM EDT /7 AM CDT/ Tuesday for LSZ162-263-264. Lake Michigan... None. && $$ SHORT TERM...Rolfson LONG TERM...07 AVIATION...lg MARINE...Rolfson
Area Forecast Discussion
National Weather Service Paducah KY
857 PM CDT Mon Oct 15 2018 .UPDATE... Issued at 856 PM CDT Mon Oct 15 2018 With a mid-evening update, will keep the current coverage and timing of the Frost Advisory in place for parts of southern Illinois, and adjacent parts of southeast Missouri and southwest Indiana tonight. However, a minor vort center (possibly a weak baroclinic leaf) has set up over extreme eastern Oklahoma this evening. This would support a greater probability of broken to overcast cloud cover over the WFO PAH forecast area through at least 6-8z (1 to 3 am CDT). After that time, some thinning/breaks should take place to reduce the opaque sky cover in and around the frost advisory area. The effective time for lowered cloud coverage to aid frost development may be only 1-3 hours. Cold air advection has been more efficient this afternoon and this evening, so had to adjust temperatures and dewpoints downward 1-2 degrees. This will place the vulnerable areas in the Frost Advisory closer to reaching critical temperature/radiational cooling levels despite a short residence time of clearing skies between midnight and daybreak Tuesday. So, no changes to the Frost Advisory. Main sensible weather changes made were to increase opaque cloud cover, reduce temperatures and dewpoints overnight. && UPDATE Issued at 620 PM CDT Mon Oct 15 2018 Revised aviation discussion for 00Z TAFs. && .SHORT TERM...(Tonight through Wednesday night) Issued at 154 PM CDT Mon Oct 15 2018 All the short term discussion is temperatures and the impact of, ie Frost and headlines thereof. Problematic is the slow clearing and light gradient that will be maintained, and there may be high clouds advecting overtop the cleared out areas. But the consensus build is that for northern reaches, where temps will drop into the lower to middle 30s, there will be enough of a clear out late, with temps low enough (low to mid 30s), to call for headline Frost across our northern tier counties...namely along and north of the Interstate 64 corridor generally. Clouds/pcpn will linger longer than model indications, although the HRRR keeps picking up on this, carrying into the evening, for our southeast counties. As surface High pressure slides east with time, then we`ll see a better clear out/cool temps with light winds as the surface High over over the Ohio valley Wed night... which may well result in another headline. .LONG TERM...(Thursday through Monday) Issued at 154 PM CDT Mon Oct 15 2018 By 12Z Thursday, the center of surface high pressure will be situated over northern portions of our area. Temperatures during the early morning hours will likely bottom out in the mid to upper 30s. With the clear and mainly calm conditions, along with those temperatures, we will likely see some frost formation, especially across southern IL, southwest IN and parts of west KY. Throughout the day on Thursday, the high will be slowly shifting east. However, our area will remain dry with highs in the mid to upper 50s. Clouds will be increasing from the west as the flow becomes southwesterly Thursday night into Friday, and advects moisture northeast ahead of an advancing cold front. The GFS insists that rain could start as early as 06Z Friday out in far western portions of the cwa. Timing and QPF between the suite of model data continues to be problematic. However, it still appears as though Friday into Friday night will be the best time frame for rain to fall. Placement of higher PoPs for each 6 hour period is what remains in question at this time. However, the GFS ensemble mean QPF is more similar to the latest ECMWF runs than it is the operational GFS. Therefore, the operational GFS may be a bit too fast bringing the rain across the area early Friday. Despite the model differences early on, most are in agreement on the departure of the rain. A weak cold front will push through the area late Friday night. We should see the rain ending during the evening hours on Friday. Surface high pressure will build into the area for Saturday resulting in some breezy conditions early in the day, slackening off later, with highs a few degrees either side of 60. Patchy frost will once again be possible late Saturday night into Sunday with lows in the upper 30s. The rest of the weekend even into Monday looks dry with below normal highs continuing (mid to upper 50s) along with most frost probable late Sunday night into Monday morning. && .AVIATION... Issued at 620 PM CDT Mon Oct 15 2018 Drier air will advect into the region tonight on light north to northwest winds as high pressure over the Plains takes control. As a result, MVFR ceilings will continue to clear from northwest to southeast through the evening, leaving behind VFR conditions during the remainder of the forecast period. && .PAH WATCHES/WARNINGS/ADVISORIES... IL...Frost Advisory from 1 AM to 8 AM CDT Tuesday for ILZ075>078- 080>084. MO...Frost Advisory from 1 AM to 8 AM CDT Tuesday for MOZ076. IN...Frost Advisory from 1 AM to 8 AM CDT Tuesday for INZ081-082- 085>087. KY...None. && $$ UPDATE...Smith AVIATION...RyanP
Area Forecast Discussion
National Weather Service Mount Holly NJ
936 PM EDT Mon Oct 15 2018 .SYNOPSIS... A cold front extended from southwestern Quebec, across the upper Ohio River Valley to the lower Mississippi River Valley this afternoon. The boundary will progress to the southeast and it should pass through our region tonight. Another cold front approaching from the northwest is forecast to arrive on Wednesday. High pressure is expected to build across our region from the west on Thursday and Friday, followed by a cold front late on Saturday. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 930 pm update: Made some minor edits to temperatures and edited PoPs/Wx grids a little bit more to match radar trends. Forecast thinking below remains unchanged at this point. 830 pm mesoscale update: I updated the PoPs/Wx grids substantially based on the past two hours of radar trends. It is becoming increasingly clear that a predecessor vort max has moved through the northern Mid-Atlantic, and the cold front is now upstream of it. When analyzing radar data over the past three hours, the narrow band of showers along the front quickly fizzled after the passage of the vort max (and attendant showers, generated from the midlevels). I suspect weak/transient subsidence upstream of the vort max combined with the nearly-nonexistent low-level parcel buoyancy has (have) countered the lift generated by the front. This process will likely continue until the next perturbation reaches near/downstream of the front, and as the 23z HRRR suggests, this may not happen until the front is near or even off the coast of New Jersey. With the above in mind, greatly reduced PoPs this evening but did keep them elevated near/east of the Delaware River 02z onward (though somewhat lower than before). Also narrowed the region at risk of lightning to the proximity of the front hour- by-hour. Overall, though, think the risk of gusty showers/storms along the front is lowering away from the coast and from Delmarva. 700 pm mesoscale update: Front is quickly approaching the area and will enter the northwestern CWA in the next hour or two. So far, the strongly-forced showers along the front have not fared well, losing some organization and intensity in the past hour or so. However, as the front moves past the higher terrain of central PA, it will begin to approach a modestly more favorable environment to initiate and sustain stronger lift/updrafts. Slab-like lift along the boundary is expected to resume the strongly-forced narrow band of showers with increasing chances of thunder as the front approaches the coast. Hi-res models showing this process occurring between 02z and 04z generally near and east of the I-95 corridor. The chances for stronger convection increase closer to the coast, and with such strong winds aloft, even low-topped convection with little or no lightning will be capable of mixing down these stronger winds, potentially producing gusts strong enough for sporadic wind damage. The main questions are if the above processes occur and when. Hi-res models have been insistent on this occurring, but have performed rather poorly with the predecessor (downstream) rain generated from higher levels (likely associated with a weak vort max). Per the 18Z NAM, the stronger vort max will be moving in from the southwest between 00z and 03z and is quite evident on moisture-channel imagery moving through the central Appalachians at this time. The contributions from large-scale lift in advance of this perturbation should aid in convective regeneration, so confidence is fairly high on the "if" question. The "when" question is more uncertain, and timing is everything given the speed of the front. If the timing of the vort max is slow even by an hour, chances are quite low of any substantive convection developing north of the Mason-Dixon Line before the front moves offshore. They remain higher in Delmarva given the northeast-southwest orientation of the front. But, per the HRRR/NAM Nest, the timing seems to favor development near or just east of the I-95 corridor between 02z and 03z. We shall see. Previous discussion... A strong upper-level trough will slide eastward from the Great Lakes and across Ontario and Quebec Canada through tonight. This will drive a deepening surface low eastward as it tracks well to our north. An associated surface cold front however will sweep across our area later tonight. Some showers will move across parts of the area into this evening well ahead of the cold front. These should be on the lighter side with the rain falling mostly from a mid level cloud deck. As this feature slides eastward an increase in the wind fields are forecast. The 500 mb flow is forecast to increase to 70-95 knots tonight as the core of an intense mid level jet streak tracks across much of New York State. As the flow, initially southwesterly, increases and transports warmer and more humid air northward, some instability is forecast to develop through the evening into the overnight hours. The forecast soundings vary to some degree on the amount of destabilization ahead of the cold front, however generally up to 500 J/KG may be realized. The setup looks to be of a high shear/low CAPE one, and with the strong wind fields coupled with a band of enhanced ascent near the cold front may result in a narrow band of forced low-topped convection. Some of the guidance including the high- res does show a line of showers organizing eastward across our area by later this evening. There is a narrow line forming in western Pennsylvania this afternoon and this should be the feature to watch. It is not all that clear how much lightning will be generated given the low instability forecast, however if the line is organized enough locally strong to damaging winds could occur briefly as the line moves through given the amount of wind above the surface. This potentially looks to be after 8 PM overall for the area from west to east and is then over with by 2 AM. This line may become better organized from about the I-95 corridor on eastward. The combination of the strong wind field and then the cold air advection in the wake of the cold front should result in a period of gusty winds associated with the wind shift. The gusty northwest winds are expected to diminish by daybreak as the strongest winds shift offshore and the pressure gradient lessens some. Temperatures may actually increase some through the evening as the flow strengthens and the low-level warm air advection occurs, then temperatures drop off with and following the showers and cold frontal passage. The dew points will also tumble overnight in the wake of the cold front. Low temperatures are mainly a model/continuity blend. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH 6 PM TUESDAY/... The flow aloft is forecast to be more zonal on Tuesday in the wake of a strong upper-level trough early on that exits northern New England. High pressure at the surface centered in the Ohio Valley is forecast to gradually extend into our area, and this will loosen the pressure gradient. A northwesterly breeze will turn west or west- southwest during the afternoon. As the cold front settles south and east of our area in the morning, it may tend to stall to our south given the flow aloft becoming more parallel to it. Some lingering showers are possible across the far southern areas early, then given dry air advection within the northwest flow should allow for a dry day. The cloud cover should clear out quickly from north to south to start the day, however mid to high level clouds may linger longer mainly from the Philadelphia metro area on southward. It will be a cool day with temperatures mainly in the 50s, however dew points are forecast to drop into the 30s for much of the area. The high temperatures are mostly a blend of guidance and continuity. && .LONG TERM /TUESDAY NIGHT THROUGH MONDAY/... We should be well into a typical autumn weather pattern from Tuesday night through Monday with the polar jet remaining over the Great Lakes and the Northeast for much of the period. A mid level short wave trough and its associated surface cold front are expected to affect our region on Wednesday. The system should bring limited moisture with it. As a result, we will mention only a slight chance of afternoon showers across the Poconos and far northern New Jersey. Ridging at the surface and aloft are forecast to result in dry and mostly sunny conditions for Thursday and Friday. Another mid level trough is anticipated for the weekend. It should bring a cold front through our region late on Saturday. We will keep a chance of showers in the forecast for Friday night and Saturday in the lift ahead of the system. Dry weather is expected to return for Sunday and Monday. Below normal temperatures are forecast through the period. The chill will be most noticeable on the days following the cold fronts. Temperatures are expected to drop into the 30s in much of our region on Wednesday night and Thursday night. A northwest wind at 5 to 10 mph may preclude the development of much frost on Wednesday night. However, the wind should become light and variable on Thursday night and there may be widespread frost in much of our area, away from urban locations and the immediate coast. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. This evening...Front will move through between 00z and 05z across the terminals, likely with showers and a quick switch to west-northwest winds at RDG/ABE around 01z-02z. Timing looks to be 02z to 04z near the Philly terminals, and there is a slight chance of lightning by this point. Confidence is too low for TAF inclusion here. At MIV/ACY, timing looks to be 03z to 05z, and the line of showers is expected to intensify to the point where mention of TS in the TAFs is needed. The main terminal impact will be the quick switch in wind direction, and it will be likely accompanied by gusts (perhaps to 30+ kts near the showers themselves). After frontal passage, any (brief) MVFR conditions will become VFR quickly as winds become 270-320 degrees with speeds 10-20 kts and higher gusts. Moderate confidence. Overnight...Winds become more northwesterly with time and should diminish to around 10 kts by daybreak. VFR. High confidence. Tuesday...VFR with northwest winds around 10 kts becoming more westerly during the mid to late afternoon. High confidence. OUTLOOK... Tuesday night...Mainly VFR. Southwest to west wind 8 knots or less. Wednesday...Mainly VFR. West to northwest wind 10 to 15 knots. Wednesday night...Mainly VFR. Northwest wind 5 to 10 knots. Thursday...Mainly VFR. Northwest wind around 10 knots. Thursday night...Mainly VFR. Variable wind 6 knots or less. Friday...Mainly VFR. Southwest wind around 10 knots. Friday night...Mainly VFR. A chance of showers. Southwest wind 5 to 10 knots. Saturday...Mainly VFR. A chance of showers. Southwest to west 10 to 15 knots. && .MARINE... A cold front will cross the area later tonight. Strong winds above the surface will result in gusty southwest winds ahead of the front, with peak gusts in the 25-30 knot range. Along and behind the front, a period of gale force northwesterly gusts are anticipated for much of the area. As a result, the Gale Warning continues for tonight. A Small Craft Advisory however continues for the Upper Delaware Bay. A narrow band of heavier showers and perhaps some embedded thunder may produce brief stronger winds later this evening into the overnight. For Tuesday, a Small Craft Advisory should be needed for the morning following the Gale as winds and seas subside through the day. OUTLOOK... Tuesday night...Westerly wind gusts may approach 25 knots on our ocean waters north of Atlantic City. Wednesday and Wednesday night...West to northwest gale force wind gusts are expected. Thursday...Northwest wind gusts of 25 to 30 knots are expected. Thursday night and Friday...No marine headlines are anticipated. Friday night and Saturday...Southwest wind gusts around 25 knots are possible. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...None. NJ...None. DE...None. MD...None. MARINE...Gale Warning until 6 AM EDT Tuesday for ANZ431-450>455. Small Craft Advisory until 6 AM EDT Tuesday for ANZ430. && $$ Synopsis...Iovino Near Term...CMS Short Term...Gorse Long Term...Iovino Aviation...CMS/Iovino Marine...Gorse/Iovino