####018005573#### FXUS61 KILN 241847 AFDILN AREA FORECAST DISCUSSION National Weather Service Wilmington OH 247 PM EDT Wed Apr 24 2024 .SYNOPSIS... High pressure over the Great Lakes will bring cool conditions tonight, with dry weather through Thursday. A warming trend will begin by the end of the week, as an upper level ridge moves east of the region, with precipitation chances beginning again by Friday afternoon. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... A cold front has now moved most of the way through the ILN WA, with northerly flow bringing drier air into the region. There is a large surface high over the Great Lake, but also a notable amount of relatively cold air at 925mb-850mb. This cool air aloft will keep clouds in place for a while, and the potential for these clouds to dissipate overnight is one of the main challenges for the forecast. This forecast has been trended slightly more cloudy than the previous update, based on the overall size and robust appearance of the cloud shield across northern OH/IN and southern Michigan. Frost and freeze conditions remain a concern for the area overnight into Thursday morning, but confidence is not high in how this will end up working out. A Freeze Warning was issued for the areas where some 32-or-lower readings appear likely, even if clouds do remain in place. A Frost Advisory was issued for a few additional tiers of counties. Despite a favorable temperature forecast, formation is actually somewhat uncertain, with winds not going completely calm and some potential for patches of clouds to persist. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH THURSDAY NIGHT/... The surface high will drift eastward into Quebec on Thursday, with generally light northeasterly flow over the Ohio Valley. Mostly clear skies should allow plentiful sunshine, with highs still below normal, but at least getting back into the lower 60s after a notably cooler-than-normal stretch. By Thursday night, some high level clouds will be moving into the area as an upper ridge moves off to the east. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... By Friday late morning, the warm front of the low to our west will be lifting into the Ohio Valley, pushing showers out ahead of it. Currently, precipitation looks to arrive Friday afternoon into evening hours on the nose of a strong LLJ. Instability looks pretty limited through this time frame, so widespread storms are not anticipated, but rumbles of thunder may be heard. Additionally, southerly winds will mix down to the surface, resulting in gustier conditions.Temperatures rise to the upper 60s/ low 70s. The warm front continues to lift through the region and by Friday overnight hours, some additional instability builds into the area, resulting in continued chances for thunder as the ILN CWA becomes warm sectored. Overnight lows fall to the upper 50s. The area remains in the open warm sector, sandwiched under strong southwesterly flow between the low pressure to our northwest and the high pressure that has been creeping toward Bermuda for the weekend. This results in wind gusts around 40 MPH, particularly in west central Ohio on Saturday and gusts in the 30 MPH range on Sunday. As of right now, we look to stay just below advisory criteria, but this might be something to watch. Additionally, thanks to the strong warm air advection regime, Saturday's hit the upper 70s with Tds in the upper 50s, while Sunday's highs reach the low 80s, Tds near 60. Precipitation chances aren't overly high during the weekend, while we're in the warm sector, however, cannot rule out periods of showers/storms, so have kept slight chance to chance in grids. By Sunday night, the upper level trough will have moved toward the western Great Lakes, dragging a secondary surface feature along with it. This brings the associated cold front into the Ohio Valley, forcing showers and storms out ahead of it for Monday. This will be one to watch for some stronger storms as ample shear should still be present and patchy SBCABE. High temperatures on Monday will be dependent on how quickly the front moves through but for now have gone with low 80s. By Tuesday, we'll notice slightly cooler temps in the post frontal regime (though, still above normal!) as high pressure builds in from the south and the area dries out. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... Some MVFR ceilings are still around the area early this afternoon, but all ceilings should lift or scatter out to VFR within the next few hours. VFR conditions are then expected through the rest of the TAF period. Northerly winds of around 10 knots are expected this afternoon, shifting to the northeast at 10 knots or less through tonight and into tomorrow. OUTLOOK...MVFR conditions possible Friday night into Saturday. Thunderstorms are possible on Monday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...Frost Advisory from midnight tonight to 9 AM EDT Thursday for OHZ042-051-053>055-060>065-070>074-080-082. Freeze Warning from midnight tonight to 9 AM EDT Thursday for OHZ026-034-035-043>046-052-056. KY...None. IN...Frost Advisory from midnight tonight to 9 AM EDT Thursday for INZ050-058-059-066. && $$ SYNOPSIS...Hatzos NEAR TERM...Hatzos SHORT TERM...Hatzos LONG TERM...CA AVIATION...Hatzos ####018005834#### FXUS63 KIND 241848 AFDIND Area Forecast Discussion National Weather Service Indianapolis IN 248 PM EDT Wed Apr 24 2024 .KEY MESSAGES... - Cool tonight into Thursday, with some frost across northern portions of central Indiana tonight. - Active pattern returns Friday into next week with above normal temperatures and frequent storm chances && .SHORT TERM (This evening through Thursday)... Issued at 247 PM EDT Wed Apr 24 2024 Rest of This Afternoon... Satellite shows large patches of the low cloud deck becoming more cellular looking with breaks in between. Thicker clouds remain across the northeastern forecast area. Thus believe that clouds will continue to slowly break up across much of the area, with thicker patches remaining in the northeast. Will allow skies to become partly cloudy most areas (far south may be mostly sunny, with far northeast mostly cloudy). The returning sunshine will allow temperatures to warm some but remain well below normal across the north. The south will be warmer but still below normal. Tonight... High pressure will remain centered well northeast of the area, but its influence will still be enough for winds to become light overnight. Lower clouds will linger across the northeastern forecast area into the night as colder air aloft hangs around. There remains higher than desired uncertainty on how long they'll stay though. The NAM would keep skies cloudy through the night, while ensembles are less pessimistic. Even if the low clouds dissipate, high clouds will be streaming in from the northwest as they flow over an approaching upper ridge. Usually, these types of issues would not have much impact. However, tonight, they will have an impact on frost potential and coverage. More clouds would mean less frost and vice versa. Would rather err on the side of caution and after coordination with neighboring offices, will go with a Frost Advisory across the north overnight tonight. Again, confidence is lower than desired. Lows will be in the middle to upper 30s most areas. Thursday... Quiet weather will continue on Thursday with high pressure in control. High clouds will pass through from time to time. Winds will still remain mainly easterly, so temperatures will not be much warmer than today. Will go with highs in the upper 50s to lower 60s. && .LONG TERM (Thursday night through Wednesday)... Issued at 247 PM EDT Wed Apr 24 2024 The long term will be the beginning of our warming trend, with 800- 700mb modest WAA initiating deep ridging aloft. Initially, surface warm air will lag behind the mid to upper level push, leaving an elongated warm-front over the Ohio Valley late Thursday into Friday. Isentropic lift along the warm front will eventually saturate the low to mid levels, leading to scattered rain showers across the State. This will primarily occur between late Thursday night and Friday afternoon, but lingering showers could remain throughout the day/night on Friday. A weak shortwave within the broad upstream portion of the upper level trough may induce enough lift for isolated to scattered showers/thunderstorms overnight on Friday, but most areas should remain relatively dry. By Saturday, central Indiana should be well positioned inside the warm sector, with surface temperatures reaching the upper 70s to low 80s Saturday afternoon. Temperatures should increase even further into Sunday as southerly low level winds increase. The current expectation is for highs in the low 80s on Sunday, but the daily record of 86 for Indianapolis is not out of reach, depending on cloud cover from upstream MCSs. These aforementioned upstream MCSs will be the main source of uncertainty for rain/thunderstorms over central Indiana on Saturday and Sunday. Overall, the environment will lack sufficient lift for convective initiation, but left over boundaries or upscale growth upstream could change this current line of thinking. Best chances for any thunderstorms would likely be over western portions of Indiana. By early next week, a cold front will approach from the west, providing an increased thunderstorm threat. Its still too far out to determine severity, but current parameter spacing expectations could lead to deep convection and a non-zero severe threat. This should become more clear in the coming days. Day 8-14: Multi-model ensemble mean shows anomalous ridging and warmer than normal temperatures for much of this period. Precipitation opportunities will still be present within less dramatic forcing regime, but with sufficient moisture and instability, leading to some convection. && .AVIATION (18Z TAF Issuance)... Issued at 106 PM EDT Wed Apr 24 2024 Impacts: - MVFR cigs are expected to steadily clear through the afternoon - Winds shifting NW to SE overnight Discussion: Current satellite displays low clouds across the region as of 17z. Throughout the day, the southern periphery of these clouds have started steadily eroding with rising cloud bases. This has allowed for all terminals to begin rising into MVFR with further clearing expected throughout the day towards VFR by 05z. Winds are expected to veer from out of the NNW to NNE through the night with winds around 5-10 knots overnight and are expected to be out of the SSE by 12z tomorrow. && .IND WATCHES/WARNINGS/ADVISORIES... Frost Advisory from 1 AM to 9 AM EDT Thursday for INZ021-028>031- 035>043-049. && $$ SHORT TERM...50 LONG TERM...Updike AVIATION...Updike/JAB ####018004312#### FXUS63 KLMK 241849 AFDLMK Area Forecast Discussion National Weather Service Louisville KY 249 PM EDT Wed Apr 24 2024 .KEY MESSAGES... * Patchy frost possible tonight, mainly in the northern Bluegrass, southern Indiana, and other typically cold spots. * Best chances for rain through next week will come Friday ahead of a warm front and Monday ahead of a cold front. * Warm and breezy this weekend, with gusts exceeding 30 mph out of the southwest at times. && .SHORT TERM /THROUGH THURSDAY/... Issued at 249 PM EDT Wed Apr 24 2024 Sfc high pressure over Ontario continues to build south into the Great Lakes, with a reinforcing cold front draped ahead of it across Ohio and Indiana into central Illinois. Stratus behind the front continues to erode and will not be a player, leaving our skies clear as winds go NE or light/variable tonight. There is the question of frost potential tonight, but the light NE breeze is maximized across the Bluegrass, where temps are otherwise expected to be the coldest. So with lows in the upper 30s/lower 40s in most places, would expect any frost to be confined to the most sheltered valleys, so no frost/freeze headlines are planned for tonight. For Friday expect full sun as sfc and upper ridging further dries and stabilizes the column. Could even see a bit of dry air mix-down in the afternoon, but winds are too light to pose any fire weather concerns. Temps will run near or just below normals for late April. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... Issued at 249 PM EDT Wed Apr 24 2024 A warm front will begin lifting into the region Thursday night into Friday ahead of a deep surface low in the central/northern Plains. A narrow corridor of precipitation will likely develop on the 'cool' side of the warm frontal boundary in response to isentropic lift in a zone of deeper moisture. Model soundings show very little, if any, instability ahead of the warm front, so thunder chances are very low with its passage. The weekend will feature above normal temperatures as the region is well engulfed within the warm sector of the Plains surface low. A decaying band of showers and perhaps a few storms could approach the region from the west on Saturday, though strong upper level ridging over much of the eastern CONUS will promote subsidence aloft and greatly reduce any shower/storm chances locally. Sunday continues to trend drier as showers/storms near and ahead of a cold front in the Plains stay well off to our west. Winds will be breezy both Saturday and Sunday as southerly to southwesterly gusts likely get to 30mph (or more) in many locations. It's not until Sunday night into Monday that our persistent eastern CONUS ridging begins to break down as an upper level low/trough swings into the upper Midwest. A line of showers and perhaps a few storms will be pushing into the region late Sunday into Monday ahead of a weak cold front. Environmental deep layer shear will be strong ahead of the front but poor mid/low level lapse rates along with sub- par low level moisture return will result in very marginal instability, so severe weather doesn't appear to be too high of a concern at this time. Drier and slightly cooler conditions will then likely persist through midweek. && .AVIATION /12Z TAFS THROUGH 18Z THURSDAY/... Issued at 1247 PM EDT Wed Apr 24 2024 Mainly VFR conditions expected across the terminals through the valid TAF period. Lingering MVFR cig at RGA will be a close call at initialization, and we'll reflect it lifting into VFR at the valid time and scattering out by 19Z. Otherwise look for sct cu this afternoon with NW winds just shy of 10 kt. Skies will clear off around sunset with winds continuing a veering trend toward NE overnight as high pressure builds into the Great Lakes. Further low-level drying will allow us to remain clear on Thursday, with light winds from the E-NE once mixing picks up again. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...None. IN...None. && $$ SHORT TERM...RAS LONG TERM...DM AVIATION...RAS ####018009206#### FXUS61 KPHI 241850 AFDPHI Area Forecast Discussion National Weather Service Mount Holly NJ 250 PM EDT Wed Apr 24 2024 .SYNOPSIS... A cold front will cross our region during today, then high pressure arrives from the Great Lakes later tonight and Thursday before shifting to our northeast and east during Friday. A warm front should lift north of our area later Saturday, then a cold front gradually approaches later Monday before moving across our area later Tuesday. && .NEAR TERM /THROUGH THURSDAY/... 245 PM...As of this hour a cold front was moving south and eastward into eastern PA and northern NJ with this feature extending south and westward from an area of low pressure over Atlantic Canada. The front, along with an associated upper level trough combined with diurnal heating has brought a fair amount of cloud cover due to Cu development and there are some isolated to scattered showers around. There's even been a few rumbles of thunder as well over SE PA. The chance for showers will continue through the afternoon as the front moves through with the limiting factors for these being more widespread being lack of moisture and that the better upper level forcing is just about to move out. Therefor POPs are only in the 20 to 30 percent range or even a bit lower over southern parts of our forecast area. Otherwise, breezy NW winds will continue this afternoon with generally falling dew points as the front ushers in drier air. Tonight, Canadian high pressure builds southward reinforcing the cool, dry air mass pushing southward. It should become mainly clear over NE PA into NW NJ with still some lingering cloud cover farther south. A Freeze Warning is in effect for the Lehigh Valley into NW NJ where temperatures are expected to fall to around or below freezing and the growing season has started. Meanwhile a Frost Advisory is in effect for Berks, Upper Bucks, and Hunterdon Counties where lows will be mainly in the mid 30s. Winds and relatively drier air could limit frost from being too extensive but decided to err on the side of caution with the advisory. For Thursday, high pressure will dominate over the mid Atlantic and northeast. A notably colder and dry air mass will be in place though despite a mainly sunny sky for most with high temperatures mostly in the 50s. An onshore wind will keep it even cooler along the coastal areas. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... An upper-level trough is forecast to be across the Northeast and Mid- Atlantic regions through Thursday night, then it shifts to our east to start Friday. Strong surface high pressure centered over the Great Lakes Thursday builds eastward through Thursday night, then shifts off the New England coast during Friday. As the center of surface high pressure slides to our north but extends over our area Thursday night, a cold night is forecast with little to no wind and a dry air mass. Much of the area will drop into the low to mid 30s with some potential for some locations getting a little colder. Areas of frost are probable, and frost and/or freeze headlines are quite possible. After a cold start Friday morning, the surface flow should start to become more southeast to even south-southeast. This will still keep some marine influence across the area, however the air mass is forecast to start modifying and therefore high temperatures will be a bit higher compared to Thursday. It will still be cooler though closer to the coast given the onshore flow. Another chilly night Friday night, however as the air mass continues to moderate the temperatures should be mild enough to keep frost not a concern at this point. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... Summary...A significant warm-up probable over the weekend and early next week. Some shower chances later in the weekend and/or early next week. Synoptic Overview...A building ridge arrives from the west as an upper-level trough lifts across the Plains and into the Midwest through Monday. As the influence of the upper-level trough gets closer late Monday and Tuesday, the ridge shifts to our east. The timing of this however is less certain as the upper-level trough in the Plains may become a closed low which tend to be slower moving (may be two separate systems). This will also have an impact on our precipitation chances Sunday through Tuesday. The overall pattern though continues to suggest that a much warmer air mass will overspread our region Sunday through early next week. For Saturday...A building ridge starts to arrive from the west and this will initially keep a cool air mass across our region. However, some warm air advection starts as more of a southerly return flow starts initiates. In addition, a warm front should lift to our north later Saturday. While a few showers cannot be ruled out with this warm front, the probability looks to be on the low side at this point. Cloud cover should dominate the sky during at least a portion of Saturday due to some increasing warm air advection, some increase in moisture, plus ahead of and with the warm front. The timing of this warm front looks to be driven by a lead upper-level trough or closed low that lifts across the Midwest which also has a surface low with it. As we start to get into the warm sector, the clouds should clear from south to north especially at night. For Sunday through Tuesday...As an upper-level trough continues to lift up across the Plains and Midwest, the downstream ridge axis slides across our region Sunday and Monday before shifting offshore into Tuesday. Surface low pressure tracks across the Great Lakes and into adjacent Canada Monday into Tuesday, and its associated cold front approaches our area Monday night. The actual cold front may not slide across our area until later Tuesday. The details however will depend on the timing and amplification of the trough. In addition, high pressure sliding east of Hudson Bay Canada Monday into Tuesday may send a cold front down across New England and closer to our area. While this front may settle into at least our northern areas Monday night into Tuesday, it should not get to far south given the continued southerly flow ahead of the aforementioned trough from the west. Plenty of warm air with increasing dew points are therefore currently forecast across the area, with high temperatures for much of the area in the 70s to even some low to mid 80s. The surface flow however looks more south or even southeast at times and this will keep it several degrees cooler at the coastal communities compared to farther inland. There is a chance for some showers and thunderstorms, especially Monday and Tuesday, however the probabilities look to be on the lower side as of now. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas... Rest of today...Mainly VFR. A brief period of MVFR conditions possible (10%) with some mainly isolated showers. 5% chance of a thunderstorm across northern terminals. Northwest winds 10 to 15 gusting 20 to 25 knots at times. High confidence. Tonight...VFR. Winds diminishing to 5 to 10 knots through the evening and also shifting gradually to more northerly and eventually northeasterly overnight. High confidence. Thursday...VFR. Northwest winds generally 5 to 10 knots before diminishing late day. Outlook... Friday...VFR. Saturday and Sunday...A period of near MVFR ceilings possible Saturday, otherwise mainly VFR. && .MARINE... Seas will remain elevated through tonight before slowly starting to come down through Thursday. For this reason, the Small Craft Advisory was extended to 16z Thursday for our northern ocean zone off the coast of Monmouth County with it running until 22z Thursday for the remaining ocean zones. Northeast winds will increase later tonight to a brief period of SCA levels of 15 to 20 gusting up to 25 knots but should otherwise be sub SCA. Outlook... Friday through Sunday...The conditions are anticipated to be below Small Craft Advisory criteria. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Freeze Warning from 3 AM to 9 AM EDT Thursday for PAZ061-062. Frost Advisory from 3 AM to 9 AM EDT Thursday for PAZ060-105. NJ...Freeze Warning from 3 AM to 9 AM EDT Thursday for NJZ001-007- 008. Frost Advisory from 3 AM to 9 AM EDT Thursday for NJZ009. DE...None. MD...None. MARINE...Small Craft Advisory until noon EDT Thursday for ANZ450. Small Craft Advisory until 6 PM EDT Thursday for ANZ451>455. && $$ SYNOPSIS...Fitzsimmons/Gorse NEAR TERM...Fitzsimmons/RCM SHORT TERM...Gorse LONG TERM...Gorse AVIATION...Fitzsimmons/Gorse/RCM MARINE...Fitzsimmons/Gorse/RCM