####018005034#### FXUS62 KRAH 230132 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 930 PM EDT Mon Apr 22 2024 .SYNOPSIS... High pressure will build overhead tonight through Tuesday, then shift to our southeast. The resulting southwest flow will bring warming temperatures through mid to late week. && .NEAR TERM /THROUGH TUESDAY/... As of 930 PM Monday... High pressure extends form the Deep South across the Carolinas under shortwave ridging in the wake of the departing upper trough. Significant drying below 500mb was observed between the 12Z/22 and 00Z/23 raobs at GSO with PW dropping to 0.3 inches. Clear skies are expected overnight with just some very thin and dissipating cirrus spilling southeast out of the Midwest. A Frost Advisory is in effect until 8am Tuesday for all of the CWA except for Guilford and Forsyth Counties tonight based on latest MET and MEX statistical guidance, which tend to be favored in strong radiational cooling scenarios. This morning's 1000-850mb thickness was 1316m at GSO which would also lean toward more mid 30s with no airmass moderation, and dewpoints are mostly int he 30s, so near surface moisture is also favorable. -BLS && .SHORT TERM /TUESDAY NIGHT/... As of 235 PM Monday... Central NC will be under the influence of shortwave ridging on Tuesday between a closed mid/upper low moving NE in the western Atlantic and a northern stream shortwave diving down into the Upper Great Lakes. So height rises and subsidence will keep us dry and sunny. At the surface, ~1025 mb high pressure centered over GA and the Carolinas on Tuesday morning will shift SE and offshore in the afternoon. This will shift the low-level flow to a southwesterly direction, helping bring 1000-850 mb thicknesses 20-30 m higher than today, supporting warmer high temperatures mainly in the lower-70s. This is still about 1-3 degrees below normal. Lows on Tuesday night will be near normal in the SE and slightly above normal in the NW, where mid and high clouds will be on the increase in advance of the aforementioned northern stream shortwave that will be moving into the OH Valley and Appalachians. This will make for fairly uniform lows in the upper-40s to lower-50s. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... As of 241 PM Monday... An upper level trough will swing across the Northeast Wednesday morning followed by a weak shortwave swinging across the northern Mid-Atlantic region Wednesday night. By Friday, upper level ridging will take over through the weekend resulting in fair weather for the latter half of the long term period. At the surface, a low pressure system centered over the southern portions of Quebec early Wednesday morning will trail a cold front south along the Appalachian Mountains. While showers will be persistent west and north of the mountains latest model guidance is showing much of the forcing loosing energy east of the mountain range thus limiting the chance for rain across Central NC. Expect some passing sprinkles Wednesday afternoon as the front moves across the region. As the front moves offshore overnight, a cool dry high pressure will build into the region with northeasterly winds taking over. If conditions clear out early enough Thursday morning, light NE winds could help result in some patchy fog across portions of the NE Piedmont and Coastal Plain. Thursday and Friday are expected to be fair weather days with mostly sunny skies and temps in the upper 60s north, to low/mid 70s across the south. As high pressure and upper level ridging strengthens across our region over the weekend and early next week temperatures are expected to increase quickly with highs in the mid/upper 70s Saturday, low to mid 80s Sunday, then by Monday mid 80s across the entire region. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... As of 715 PM Monday... 24 hour TAF period: High confidence VFR conditions will prevail through the TAF period. Expect clear skies and calm to light winds overnight, with continued clear skies and winds increasing from NW to SE through the afternoon Tuesday. Outlook: Largely VFR conditions are expected through Sat. There are two possible exceptions. First would be a small chance for a brief period of light showers/sprinkles and/or borderline VFR/MVFR cigs as a weak cold front moves into/through the area on Wednesday. The other would be a possible brief period of borderline VFR/MVFR cigs Thu morn/early aft. However, confidence in both occurrences of restrictions remains low at this time. && .RAH WATCHES/WARNINGS/ADVISORIES... Frost Advisory from 2 AM to 8 AM EDT Tuesday for NCZ007>011- 023>028-038>043-073>078-083>086-088-089. && $$ SYNOPSIS...GIH NEAR TERM...BLS SHORT TERM...Danco LONG TERM...CA AVIATION...KC ####018005286#### FXUS66 KLOX 230133 AFDLOX Area Forecast Discussion National Weather Service Los Angeles/Oxnard CA 633 PM PDT Mon Apr 22 2024 .SYNOPSIS...22/217 PM. Strengthening onshore flow and a deepening marine layer will bring low clouds, fog, and drizzle to the coast and coastal valleys throughout this week. Cool conditions will continue, with high temperatures several degrees below normal each day this week. A couple of weather disturbances will track across the area later in the week, bringing a small chance for light rain showers for mid to late week. && .SHORT TERM (MON-THU)...22/222 PM. Strong onshore pressure gradients will persist through much of this week. These onshore gradients will further strengthen through mid-week in response to midlevel ridging focusing the strongest surface heating over the central Great Basin. Diurnally enhanced onshore gradients for LAX-DAG are forecast to reach 8-9 mb each day through Thursday. In addition, for Wednesday night into Thursday, a midlevel low will progress eastward over the East Pacific and across southern California. This will further reinforce and deepen the marine layer over coastal areas and coastal valleys later this week. Widespread low clouds and fog are expected to accompany the deepening marine layer, which will also cool temperatures across the region. High temperatures are expected to be in the 60s in most areas each day, except rising into the 70s over the Antelope Valley away from the marine layer. In addition, the marine layer will significantly deepen to depths over 2500-3000 feet tonight into Tuesday and then depths over 4000 feet for Thursday. This will support drizzle over many areas -- especially during the evening, overnight, and morning hours. Dry conditions in the mid and upper troposphere will limit the potential for measurable rainfall, though a few light showers could accompany the passage of the midlevel low late Wednesday night and Thursday morning. .LONG TERM (FRI-MON)...22/227 PM. Following the passage of the aforementioned midlevel low, temperatures aloft will cool and onshore pressure gradients will weaken. These factors will allow the marine layer to lose depth and weaken to some extent by the end of this week, with the extent of fog and drizzle correspondingly lessening. Thereafter, further cooling aloft, decreasing onshore flow, and weakening of the marine layer will occur with the glancing influence of a deep midlevel trough amplifying over the Great Basin late Friday into the upcoming weekend. However, despite the weakening marine layer, cooling aloft will maintain high temperatures in the 60s in most areas through Friday. Thereafter, temperatures are expected to warm a few degrees by Sunday as midlevel heights rise behind the deeper trough. Regarding precipitation, there will be a slight chance for light showers Friday into Friday night in conjunction with the second disturbance glancing the area, which will be followed by dry conditions. && .AVIATION...23/0137Z. Moderate/Low confidence in coastal and valley TAFs and high confidence in desert TAFs. Lower confidence for coastal/valley sites due to uncertainties in timing of flight category changes. For tonight, drizzle is likely for much of the coast as the marine layer grows, likely bringing MVFR to IFR CIGs. Low confidence in timing of lowest cigs and drizzle. KLAX...Moderate to low confidence in 00Z TAF. Timing of flight category changes between IFR and MVFR conditions could be +/- 3 hours of current forecasts. No significant easterly wind component is expected. KBUR...Moderate to low confidence in 00Z TAF. Lower confidence in timing of IFR conditions and drizzle. && .MARINE...22/129 PM. For the Outer Waters, moderate to high confidence in current forecast. Today through Wednesday, high confidence in winds and seas remaining below Small Craft Advisory (SCA) levels. For Thursday and Friday, high confidence in winds increasing to SCA levels with a 40% chance of Gale force winds across PZZ673 and PZZ676 Thursday and increasing to 70% on Friday. By Friday night the significant wave height could be in the 10-12' range. For the Inner Waters north of Point Sal, high confidence in current forecast. Today through Wednesday, winds and seas will remain below SCA levels. For Thursday and Friday, about a 40% chance of winds increasing to SCA levels, mainly in the afternoon and evening hours. For the Inner Waters south of Point Conception, moderate to high confidence in current forecast. Today through Wednesday, high confidence in winds and seas remaining below SCA levels. For Thursday, Friday, and into Saturday morning there is a 50-70% chance of winds increasing to SCA levels, especially across western sections. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...Cohen AVIATION...Phillips MARINE...jld SYNOPSIS...Cohen weather.gov/losangeles Experimental Graphical Hazardous Weather Outlook at: https://www.weather.gov/erh/ghwo?wfo=lox ####018004956#### FXUS63 KABR 230134 AAB AFDABR Area Forecast Discussion...UPDATED National Weather Service Aberdeen SD 834 PM CDT Mon Apr 22 2024 .KEY MESSAGES... - Cooler and windy on Tuesday behind a passing cold front overnight. - Pattern becomes more active by week's end with increasing chances for showers and thunderstorms by Friday into the start of the weekend. && .UPDATE... Issued at 833 PM CDT Mon Apr 22 2024 Forecast is doing just fine so only minor updates for this evening. && .SHORT TERM /THIS EVENING THROUGH TUESDAY NIGHT/... Issued at 327 PM CDT Mon Apr 22 2024 Plenty of dry air working into the CWA this afternoon, with most areas along and west of the James River in the 10 to 20 percent range. Areas further east are still expected to see a drop in RH over the next couple hours as drier air continues to advect eastward in the post-frontal air mass. Highest wind gusts from 40 to 50 mph have been occurring across central/north central SD today, and earlier issued a Wind Advisory to cover this. Will leave the headlines in place until its current expiration time of 01Z. Will be watching a cold front drop south across the area overnight, with decent cold air advection and an uptick in northwest winds later tonight (after a lull in winds after sunset), along with cooler temperatures for Tuesday. In the lower levels (925mb), we start off around +14C to +15C at 00Z this evening, but then cool to around +5C to +7C by 12Z Tuesday. Looking for a bit of a setback with highs on Tuesday compared to today, with readings dropping back into the mid 50s to low 60s. As for winds, they appear to stay generally below advisory levels for the time being, and in fact the strongest winds may be morning into early afternoon, with diminishing winds as the afternoon progresses on Tuesday. High pressure then settles in over the eastern Dakotas and Minnesota Tuesday night. This will bring mostly clear skies, light winds, and chilly temperatures perhaps below freezing for some areas. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Issued at 327 PM CDT Mon Apr 22 2024 Beginning 12Z Wednesday, our forecast area will be under the influence of high pressure at the sfc and aloft. The center of the sfc ridge will have translated east of our area Wednesday morning while the ridge aloft will be building across the Northern Plains Wednesday into Thursday. Return flow on the backside of the sfc high will allow south to southeast winds to commence on Wednesday and persist through Thursday. A warmer air mass will be drawn northward into our area. 925mb temperatures are progged to warm to between +10C to +15C on Wednesday and to between +15C to around +20C on Thursday. This should translate nicely into daytime temperatures in the 60s and 70s. We'll just have to keep an eye on cloud cover vs sunshine, which could impact how far readings warm. A tighter pressure gradient these days will lead to gusty south to southeast winds. Models continue to peg Thursday as the windiest day across the board for our CWA. Most of our zones have a 50-90 percent chance to see wind gusts reach or exceed 40 mph. The upper flow pattern will begin to shift by the end of the work week. An upper trough is progged to trek across the 4 Corners region turning our flow southwesterly. This system is forecast to lift northeast into our region on Friday into Saturday. Sfc low pressure in conjunction with this upper disturbance will increase our rainfall chances by early Friday. In fact, during the day Friday into Friday evening appear to be the wettest period from this system. Lingering rain showers will be possible into the start of the weekend, but guidance does hint that a drying trend may take hold for a short time anyway. Another follow on upper trough is progged by longer range guidance to take a similar track early next week. This could increase our pcpn chances again by late in the weekend into Monday. Models are still fluctuating on how they handle this system, so uncertainty still remains. The 12Z deterministic set has latched onto a bit of different solution from previous runs in taking this early next week system just a bit farther south and east of our forecast area. We'll just have to keep an eye on trends during the next few days. && .AVIATION /00Z TAFS THROUGH 00Z TUESDAY/... Issued at 608 PM CDT Mon Apr 22 2024 Terminals KABR,KATY,KPIR,KMBG VFR conditions are forecast through most of the region tonight. However, lower cigs may sneak into the KABR/KATY locales Tuesday morning for a time. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...TDK SHORT TERM...TMT LONG TERM...Vipond AVIATION...TDK