####018005187#### FXUS63 KFGF 250255 AFDFGF Area Forecast Discussion National Weather Service Grand Forks ND 955 PM CDT Wed Apr 24 2024 .KEY MESSAGES... - Near critical fire weather conditions are forecast Thursday late morning through afternoon. - Friday through the weekend: Greater than 50% chance for more than a half inch a of rain across the area. Amounts over 1" tied to isolated thunderstorm activity. && .UPDATE... Issued at 953 PM CDT Wed Apr 24 2024 Some radar returns associated with light precipitation aloft in South Dakota may move into southeast ND into west-central MN tonight. However, due to very dry air underneath where precipitation is being produced, most if not all is expected to evaporate before reaching the ground. Dry conditions are still forecast throughout the night despite what radar may imply. UPDATE Issued at 645 PM CDT Wed Apr 24 2024 Satellite showing numerous thermal anomalies associated with prescribed and agricultural related fires today, of which are producing areas of light smoke. This along with higher cirrus moving across the region will give the sky that hazy-filtered sun look to end the afternoon. Overall, no change in previous thoughts within the Discussion. && .DISCUSSION... Issued at 247 PM CDT Wed Apr 24 2024 Sunny skies prevail through the remainder of today with light winds and low RH keeping near critical fire weather in place until RH begins to climb with the collapse of diurnal heating this evening. RH values as low as the upper 10s may continue to drop slightly as we reach peak mixing in the next few hours by 4-5 pm but should remain above 15 percent. The overall synoptic pattern shows ridging over the eastern conus steering southwest flow aloft into our area with an upper low ejecting into the northern plains by Friday morning. It is the combination of this approaching low and the exiting surface high tonight that is giving us an enhanced low level wind field tomorrow. Warm air advection will keep us very warm Thursday in the low to mid 70s for highs though increasing cloud cover by the afternoon could limit mixing somewhat. Overall expect the WAA to overcome this and realize max temps over 70 for most. Sustained wind speeds while impressive are unlikely to reach wind advisory criteria but the combination of winds in the 20-25 mph, gusts of 30-35 mph, and RH of 30-40 percent could yield another day of near critical fire weather conditions. Very unlikely to reach red flag as RH is progged to bottom out on the lower 30s to isolated upper 20s for only a few hours and winds wont be strong enough to compensate (might relocate a few trash cans though). As the upper low near thursday night (still located in eastern CO/western NE/KS) WAA and deformation will allow for increasing precip chances by the late evening though will likely take a few hours of moistening before echos actually begin reaching the surface. PWAT values of 0.6 to 0.9 for a sustained period should allow for efficient warm rain process as widespread totals over 0.5" seem likely as all clusters show at least a 50% across the forecast area by Sunday morning. Those higher totals nearing an inch or greater will be tied to 1) the exact track of the low, and 2) any MUCAPE that can be found to produce thunderstorms. A little more confidence in the first condition currently with a track to our southeast keeping the higher PWATs out of our area through any enhanced pockets of 850/700mb WAA could be enough to generate some MUCAPE that ensembles are not currently able to resolve thus certainly not ruling out the for isolated thunder and some of those higher 1"+ totals to be realized. As this low escapes northeast over the eastern US another low will track through the southwest flow, though with less moisture available not expecting quite as high rain totals. The active pattern persists into next week with southwest flow and and open feed to gulf moisture likely keeping us above average for the period in terms of moisture and even temperature, a stark change from the mostly dry conditions of the past few weeks and even months. && .AVIATION /00Z TAFS THROUGH 00Z FRIDAY/... Issued at 645 PM CDT Wed Apr 24 2024 VFR conditions are forecast throughout the TAF period. Light winds under 10 kt this evening will markedly increase between 11Z-14Z as strong low level, southerly winds aloft move over eastern ND into western MN. These south winds forecast to be 17-27kt gusting 25-35kt (highest at GFK and FAR) will persist through much of the day Thursday. Some brief gusts to 40kt are possible (60%) at GFK and FAR, more likely to occur during the afternoon hours. Low level wind shear is also forecast at DVL between 10Z-13Z. Winds will decrease some near and just after 00Z, but still remain above 15kt. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...CJ DISCUSSION...TT AVIATION...CJ ####018006872#### FXUS61 KPBZ 250256 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 1056 PM EDT Wed Apr 24 2024 .SYNOPSIS... Colder air filters in tonight with decreasing cloud cover. Temperatures rebound tomorrow with marginal wire weather. The weekend remains warm with intermittent precipitation chances. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... KEY MESSAGES: - Freeze warning and frost advisories are in effect north and west of the Pittsburgh metro beginning at midnight. ------------------------------------------------------------------ Update... Adjusted overnight lows and sky cover based on the latest satellite, surface observations, and near term model output. It appears the low level moisture will remain locked below a subsidence inversion for a good portion of the area overnight. Clearing will likely take place under dry advection, mainly north and west of Pittsburgh, where frost and freeze conditions are likely. Previous discussion... The forecast remains on track late this evening with ongoing cold advection in northwest flow reinforcing saturation and cloud coverage in the low-levels through the early overnight hours before drier air advects in from the north and low level flow veers more northwesterly cutting off the lake source. Right now, there is high confidence in a freeze (80% to 100%), potentially even hard freeze (60% to 80%), north of I-80 where clearing is expected early tonight and radiational cooling will develop. Elsewhere, the degree of cooling will depend on clearing which remains the forecast challenge for tonight. The freeze warning was hoisted for where probabilities of subfreezing temperature are greater than 50%. For the areas in the warning south of I-80, clearing is not guaranteed with large spread between the low and high end of cloud cover in the latest hi res ensemble guidance. Thus, there is a failure mode for the warning. On the contrary, clearing may go as far as covering areas in the frost advisory, where freezing temperatures are also not out of the realm of possibility. Thus, there is generally high uncertainty in temperatures in-between I-80 and the advisory area; a sharp temperature gradient may orient along the cloud extent maxima. Elsewhere, clearing is not favored with probability for less than 50% cloud cover generally sitting below 50%, thus frost formation and significant cooling are also not favored. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... KEY MESSAGES: - Dry conditions with a warming trend are expected through Friday; showers return Friday night. ---------------------------------------------------------------- Thursday will bring mundane weather. In the morning and early afternoon, mixing will act to gradually erode the lingering stratocumulus deck. This will lend to a rebound in temperature under clear skies and high pressure. The NBM clear sky under-mixing bias was accounted for in the forecast as daytime highs were adjusted upward a couple of degrees and daytime dews minimize at the NBM 10th percentile. This has dropped relative humidities into the upper 20s and lower 30s. Dead and fine fuel moistures may dip below 10% during the day, although winds will remain calm to light. This will lead to another day of marginal fire weather, with conditions most favorable in northwestern Pennsylvania. A temperature and dewpoint push is expected through Friday as the high moves east and a southerly component to the flow reestablishes. Low-QPF rain showers are possible Friday night and early Saturday morning as a warm front approaches from the south. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... KEY MESSAGES: - Much warmer through the weekend - Highest chance for showers on Saturday, and again Monday through Tuesday ------------------------------------------------------------------- Model ensembles indicate the initial shortwave and warm front supported rain will continue to cross the region on Saturday. The front is expected to lift north of the region Saturday night, as a strong ridge builds across the SE CONUS to the Upper Ohio Valley region. Mainly dry weather is expected Saturday night and Sunday with the ridge axis across the area. There could be enough diurnally driven instability to result in an isolated afternoon thunderstorm Sunday, though most of the day should be dry, with temperatures in the upper 70s to the mid 80s. 1000-500mb height approach 583 dam Sunday into Monday, with 850 mb temperatures peaking around 14 deg C. Model ensembles indicate the ridge should slowly shift eastward to the East Coast late Monday and Monday night, as the next shortwave trough and surface cold front approach from the Midwest. Scattered showers and thunderstorms are possible Monday with building diurnal instability in moist SW flow ahead of the trough. More numerous showers and possible thunderstorms are expected Tuesday as the trough/cold front cross the region. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... Northwest flow and ongoing shortwave troughing are keeping MVFR stratocumulus (IFR at FKL) in place across much of the region, with locations near/south of the Mason-Dixon Line escaping restrictive impact for now. As a vorticity maximum sinks south and east this evening, lower clouds will accompany it, providing MVFR ceilings to MGW by late evening. Northwest wind will continue to diminish with time, eventually going light by midnight. MVFR ceilings will largely persist through the night and past sunrise with moisture trapped under an inversion. FKL will continue to deal with IFR and potentially LIFR ceilings overnight as the low levels cool. Past sunrise, as high pressure tracks to the north, the low cloud deck will mix out, leading to VFR conditions by midday that will linger through the afternoon, along with light wind. .Outlook... VFR conditions are expected Thursday and Friday. The probability of showers and isolated thunderstorms increases Saturday. This will come with additional restrictions likely. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...Freeze Warning until 10 AM EDT Thursday for PAZ007>009-013>016- 022-077. Frost Advisory until 10 AM EDT Thursday for PAZ020-078. OH...Freeze Warning until 10 AM EDT Thursday for OHZ039>041-048. Frost Advisory until 10 AM EDT Thursday for OHZ049-050-057-058. WV...Frost Advisory until 10 AM EDT Thursday for WVZ001. && $$ SYNOPSIS...Milcarek NEAR TERM...WM/MLB/Milcarek SHORT TERM...Milcarek LONG TERM...WM AVIATION...CL ####018004642#### FXUS61 KCTP 250256 AFDCTP Area Forecast Discussion National Weather Service State College PA 1056 PM EDT Wed Apr 24 2024 .SYNOPSIS... Widespread frost and freeze conditions are expected tonight and Friday morning, with high pressure providing dry and mostly sunny conditions. Clouds increase late Friday leading to a chance of showers Friday night and into the weekend before it turns much warmer for Sunday and Monday. && .NEAR TERM /THROUGH THURSDAY/... Cloud cover is a steadily decreasing, but still a little too slowly. Dry, cold air is punching in from NY and should help temps get to freezing where we have the warning up. The expected frost for the wrn highlands is in jeopardy if we can't shake those clouds. But, we'll continue all flags as is with the expectation that the clouds will continue to diminish across the board. The SHRA have fizzled to nothing over the E, as expected. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/... Chilly/cold start Thursday followed by mostly sunny conditions allowing temps to warm into the mid 50s to around 60F. Very dry air/below normal pwats ~0.20 inches combined with HREF ens min and mixed Td sounding signal suggests a floor for minRH as low as 10-15% across the northern tier. The abnormally dry air and favorable radiational cooling conditions will support renewed frost/freeze concerns tomorrow night into AM Friday. This risk is highlighted in the HWO. The sfc high strengthens to +2SD or ~1035mb as it drifts over interior New England to Long Island by 12Z Saturday. Rain free wx conditions will continue through the end of the week/Friday with sun mixing with high clouds and max temps trending warmer into the upper 50s to lower 60s. Showers along a warm front are likely to reach western PA by daybreak Saturday based on latest operational model/ens consensus. No frost/freeze concerns for Friday night into AM Saturday with increasing clouds and fcst lows 38-45F. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Late evening update holds very few changes to the long term. Have kept the forecast very consistent with a very warm period coming up. Prev... The weekend appears somewhat unsettled, with a warm front arriving Saturday and warm sector struggling to overspread central PA. It won't be raining all the time, but a couple of showers are likely on Saturday with a t-storm possible on Sunday. Upper ridging should eventually win out by early next week, allowing for drier wx and much warmer temps with highs surging through the 70s and perhaps topping 80F across the south on Sunday. The warmest day of the extended period will be Monday as temperatures soar into the 80s areawide. A bit humid as well with fcst Td around 60F. This could support overnight lows near record levels next week (near 60F). Precipitation will be tough to come by in the extended period without much gulf moisture sourcing. Decaying systems that bring severe weather to the Plains will struggle to stay together and 7-day precipitation forecasts show very little rainfall across southeast PA through the middle of next week with amounts only approaching 0.75" in northwest PA. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... A northwesterly flow continues to gust 15-20 kts this evening. Borderline IFR/MVFR cigs were observed across NW PA (BFD), with borderline MVFR/VFR cigs down the western highlands into JST and predominantly VFR conds elsewhere. JST should see cigs drop to solidly MVFR overnight, while the IFR cigs at BFD are expected to eventually scatter out. Expect predominantly VFR conds to persist at the other central PA TAF sites overnight. Wind gusts will diminish, although a light northerly sfc flow should persist in most areas. Skies will clear areawide on Thursday, with widespread VFR conds and a light northeasterly sfc flow of 5-10 kts expected. Outlook... Thu-Fri...Predominantly VFR conds under high pressure. Fri night-Sat...Patchy rain developing from west to east. Sun...Isold SHRA/TSRA possible. Mon...Predominantly VFR. && .CTP WATCHES/WARNINGS/ADVISORIES... Freeze Warning from 2 AM to 8 AM EDT Thursday for PAZ004-005- 010-011-017>019-045-046-049>053. Frost Advisory from 2 AM to 8 AM EDT Thursday for PAZ024>028- 056-057-059. && $$ SYNOPSIS...DeVoir/Steinbugl NEAR TERM...Dangelo SHORT TERM...DeVoir/Steinbugl LONG TERM...Banghoff/Dangelo/Evanego AVIATION...Evanego ####018006612#### FXUS66 KLOX 250256 AFDLOX Area Forecast Discussion...UPDATED National Weather Service Los Angeles/Oxnard CA 756 PM PDT Wed Apr 24 2024 .SYNOPSIS...24/538 PM. Strong onshore flow and a deep marine layer will keep temperatures much cooler than normal across much of Southwest California through Friday. Morning patchy fog and drizzle are expected across portions of the coast, valleys, and foothills. Warmer weather is expected by the weekend into early next week. && .SHORT TERM (WED-SAT)...24/756 PM. ***UPDATE*** Still plenty of cloud coverage visible in the satellite imagery, and expect the low clouds to extend well inland tomorrow morning as a trough will lift the marine layer. Look for morning drizzle in most of southeast LA County. The patch of clouds that contained some lightning activity mentioned in the previous short term discussion seems to be dissipating to our south and should not affect the sky this evening over our area. It is still looking good for advisory strength winds beginning later Thursday evening in the western Santa Ynez Mountains, northern I-5 corridor, and Antelope Valley. Winds will increase in strength and coverage in Friday. ***From Previous Discussion*** A deep marine layer remains in place, however the inversion remains weak so clouds are generally focused across the inland valleys up against the south facing foothills as well as the Central Coast. Confidence remains low with regard to the sky coverage later tonight and Thursday as a trough approaches from the southwest. Satellite imagery shows some baroclinicity to it with even several lightning strikes near the low center earlier today. Models indicate significant weakening of the system as it continues it's trek towards either northern Baja or southern San Diego County so chances for any redevelopment are slim. Still, the low and mid level lifting associated with the low could generate some morning drizzle across southeast LA County. Many of the ensemble solutions suggest this as well. Following the trough passage Thursday afternoon, increasing west to northwest winds are expected that will continue into Friday. In fact Friday has some of strongest winds this week with speeds up to 40 mph near and over the coast and up to 50 mph across the mountains and Antelope Valley. Expect there will be a need for wind advisories, possibly as early as late Thursday afternoon, but certainly by Friday. Later Friday into early Saturday there is a 10-15% chance of light measurable rain across the interior mountains from far western LA County to Santa Barbara County as an inside slider trough brings some additional energy aloft as well a little bit of moisture. Snow levels are at least 6000 feet so there's no threat of snow over the Grapevine, but there may be some light showers there and along the border with Kern County to around the Carrizo Plain in southeast SLO County. All that should end around sunrise Saturday leaving behind sunny skies in all areas with slightly warmer temperatures than Friday. .LONG TERM (SUN-WED)...24/201 PM. Sunday and Monday will be similarly nice days across the area with minimal stratus and warming temperatures. Monday will likely be the warmest day in this stretch with highs in the mid 80s in the valleys and upper 60s and 70s near the coast. The rest of the week will be cooler with increasing low clouds and fog as well as onshore winds, particularly later in the week as another cold upper low drops out of the Gulf of Alaska. && .AVIATION...25/0207Z. At 0030Z at KLAX, the marine layer was 1400 feet deep. The top of the inversion was at 2300 feet with a temperature of 11 C. High confidence in desert TAFs. Low to moderate confidence in remaining TAFs. Cigs will generally be high MVFR to VFR, except lower in some mountain/foothill areas. Much uncertainty of cig arrivals and dissipation, but expecting most TAF sites to see cigs at times from 12Z onward. KLAX...Moderate confidence in TAF. There is a 20-30% chance of no cigs or cigs a category high than forecast during the period. Cigs appear likely after 10Z. No east wind component expected. KBUR...Low to moderate confidence in TAF, due to uncertainty in arrival of cigs. There is a 20-30% chance of no cigs or cigs a category high than forecast during the period. && .MARINE...24/229 PM. In the Outer Waters, good confidence that winds will reach Small Craft Advisory (SCA) levels in the southern zone (PZZ676) this afternoon thru late tonight, with a 30% chance in the two northern zones, particularly around Point Conception. SCA conds are expected Thu morning thru Sun. There is a 50-70% chance of gales starting Thu evening thru Mon, with the highest chances for the southern zone (PZZ676). For the Inner Waters N of Pt. Sal, moderate to high confidence in the forecast. SCA level winds are likely in the afternoon/evening hours Thu-Sun. There is a 50% chance of gales Fri afternoon into late Fri night. In the Inner Waters S Pt Conception, moderate confidence. SCA conds are likely in the SBA Channel and the western portions south of Point Mugu during the afternoon/eve hours today and Thu. SCA conds are likely in the SBA Channel and portions of the southern inner waters during the afternoon and night hours Fri-Mon. There is a 50-60% chance of gales starting Fri morning into Sat. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...Small Craft Advisory in effect from 9 AM Thursday to 3 PM PDT Friday for zones 645-670. (See LAXMWWLOX). Gale Watch in effect from Friday afternoon through late Friday night for zones 645-655-670. (See LAXMWWLOX). Small Craft Advisory in effect until 3 AM PDT Thursday for zones 650-655-676. (See LAXMWWLOX). Gale Watch in effect from Friday morning through Saturday morning for zones 650-673. (See LAXMWWLOX). Small Craft Advisory in effect from 9 AM Thursday to 9 AM PDT Friday for zone 673. (See LAXMWWLOX). Gale Watch in effect from Thursday evening through Saturday morning for zone 676. (See LAXMWWLOX). && $$ PUBLIC...MW/jld AVIATION...Phillips/Schoenfeld MARINE...DB/Schoenfeld SYNOPSIS...jld weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox