Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/13/23

Area Forecast Discussion
National Weather Service Cheyenne WY
522 PM MDT Wed Apr 12 2023 .SHORT TERM...(This evening through Friday) Issued at 225 PM MDT Wed Apr 12 2023 Well above average temperatures continue to impact the region this afternoon as observations range from the 70s and 80s east of the Laramie Range, and 50s to 60s west of the Laramie Range. Several areas have already broken the daily record high, including SNY, BFF, AIA, and CYS. Gusty southwest winds are bringing in much appreciated warmth to the area ahead of a slow-approaching frontal boundary on our northern forecast borders. However, this has resulted in elevated fire weather concerns for the I-25 corridor into the NE Panhandle. We will continue to monitor satellite imagery due to the well above average temperatures and dry conditions combining with the breezy winds in the event new fire activity appears. Light rain showers are appearing on radar as weak echoes are being captured due to some cumulus clouds east of the Laramie Range. The rest of the afternoon into the evening hours will bring light rain showers, and even the potential for a rumble of thunder along the stalled cold front boundary of the northern NE Panhandle. The NamNest and HRRR are highlighting a region of Niobrara, Sioux, and Dawes county where weak rain showers could result in localized strong wind downdrafts. Modeled soundings show inverted-V features, and DCAPE values of 750-1300 J/kg that are present between 21Z-3Z today. Should this occur, brief wind gusts of 40-50+ MPH may occur in the aforementioned areas. Overnight temperatures should remain mild, with lows in the 40s and 50s east of the Laramie Range, and the 30s/40s west of the Laramie Range. This could assist with increased snowmelt occurring in the higher terrain. We will monitor the AHPS hydrographs to see if river levels creep up to near any action stage criteria by early tomorrow morning. Hi-res guidance does depict some light rain shower activity being possible by early Thursday morning along the Laramie Range and the foothills, but it is unlikely to be much more than a few sprinkles. Thursday and Friday will be active with respect to a large weather shift from above average temperatures back to near or below normal readings. We will have above average temperatures ahead of a slow advancing cold front from the west and north. Strong WAA will occur ahead of this frontal passage, leading to several areas seeing daytime highs in the 70s to low 80s from a corridor of I-25/HWY-26 to the east and southeast. Other regions will see cooler temperatures due to cloud cover and precipitation occurring. With the warmer temperatures and southwesterly flow being present, it will increase the chances for fire weather concerns. Low RH values and breezy winds have prompted a Fire Weather Watch for FWZs 435-437 in the NE Panhandle from 18Z-0Z Thursday afternoon. Forecast zones further to the west and north are likely to see an earlier daytime high temperature before temperatures cool the remainder of the day. With the cloud cover being present from west to east, some locations across Carbon and Albany County may struggle to reach the forecast high. One additional concern to mention is that there will be very strong surface pressure gradients present on Thursday because of the cold FROPA. The gradients really begin to tighten by Thursday afternoon across the cwa, especially our western forecast zones. The winds aloft are not all that strong, but there will be strong subsidence coupled with the tightened shallow pressure gradients near the surface. There is not a mountain wave signature modeled at this time, but the wind prone and gap areas of southeast WY near Arlington and Elk Mountain could easily gust near or above 55MPH Thursday. The next forecast package may include a short-fused High Wind headline despite the wind direction not being favorable as a southwesterly component. Thursday evening includes the chance for rain showers and general thunder to be present, especially the southern tier of the NE Panhandle. SPC day 2 outlook does include a sliver of Marginal Severe Wx being possible for the BFF/IBM/SNY/AIA areas. MUCAPE values look meager, at or below 500 J/KG. But there are steep lapse rates, moisture, and forcing thanks to the frontal boundary being present. Isolated rain showers east of I-25 into the NE Panhandle will be present Thursday night, with a rain/snow mix and snow showers west of I-25 slowly advancing to the east by daybreak Friday. With the increased sun angle, and 700mb temperatures struggling to stay below -5C to -10C on Friday, there is the potential for the rain/snow line to retrograde to the north and west. At this time of inspection, snowfall accumulations will likely be confined to the higher terrain of the Laramie Range, and Snowy/Sierra Madre Ranges. Winter headlines do not appear likely at this time regarding Thursday night and Friday. Daytime highs on Friday will be much colder due to CAA and cloud cover being present. Would expect a large swath of 30s to upper 40s for a majority of the cwa, with potentially 50 degrees being achieved in the North Platte River Valley. Any lingering precipitation should begin to wind down by late afternoon into early Friday evening. .LONG TERM...(Friday night through next Wednesday) Issued at 235 PM MDT Wed Apr 12 2023 Medium to long range models in good agreement this weekend and early next week, but solution then diverge significantly for the middle portion of next week. For Saturday, Pacific upper level trough will be exiting the area to the east and northeast Friday night and early Saturday. Models show that most of the dynamic forcing will be well east of the Wyoming/Nebraska border by late Friday evening with a secondary disturbance aloft, behind the primary trough axis, digging southeast across southern Wyoming. There should be enough convergence and topographic lift to initiate widely scattered or scattered snow showers across Carbon, Albany, and the western portions of Converse, Platte, Laramie Counties along Interstate 25 into early Saturday afternoon. Models indicate quite a bit of dry air behind the main trough, so do not expect a significant coverage of precipitation outside of the mountains. Increased POP between 20 to 40 percent, with lower probs east of I-25 through Saturday afternoon. Any snow accumulations should be mainly confined to the southeast Wyoming mountains during this time period. Expect windy to very windy (gusts of 45+ mph) conditons across some of the wind prone areas too as low level pressure gradients increase through Saturday night. Do not expect High Wind Warning criteria at this time. All models then show a broad upper level ridge axis translating eastward into the Rocky Mountain Region and amplifying as it tracks eastward. Sunday through most of Tuesday should be much warmer than normal with daytime highs returning to the 60s and 70s outside of Carbon County. Lingering surface snowpack across Carbon County may result in temps in the 40s and 50s, but did not go quite that low yet since some of this snowpack will likely melt leading up to Monday. For now, did lower temperatures a few degrees for Saratoga, Rawlins, and Dixon. Otherwise, dry weather is expected through Monday night with increasing cloud cover ahead of the next system. Low confidence forecast once we get into the middle portion of next week (late Tuesday and Wednesday). Models and ensemble are struggling with the timing of the next Pacific trough approaching the region from the Pac NW coastline. The ECMWF and the Canadian shows the trough moving across the area bringing rain/snow and much colder temperatures to southeast Wyoming by Monday night. The GFS on the other hand keeps the ridge axis over our eastern zones across the high plains with dry weather. Most ensemble members (~75%) agree with the GFS and delay the arrival of the cold front until later in the week. With this in mind, blended POP forecast with the CONSALL and nudged POP forecast on the lower end of the slight chance scale due to lower than average confidence until late Wednesday. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 521 PM MDT Wed Apr 12 2023 Isolated showers will continue in far northwest Nebraska this afternoon. CDR and perhaps AIA may see brief instances of light rain as weak convection moves through. Any lingering showers will quickly diminish after sunset. Gusty southwest winds will also diminish at sunset area-wide. Expect VFR conditions through the forecast period. && .FIRE WEATHER... Issued at 151 PM MDT Wed Apr 12 2023 Elevated to near critical fire weather conditions will remain present this afternoon and again for Thursday afternoon. Overnight humidity values will recover to 45-65 percent by morning for FWZs east of the Laramie Range. Minimum humidity values between 10-15 percent will combine with breezy southwest winds of 15-25MPH on Thursday. Red Flag conditions are possible in the Nebraska Panhandle from 1200-1800 for FWZs 435-437. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...None. NE...Fire Weather Watch Thursday afternoon for NEZ435>437. && $$ SHORT TERM...BW LONG TERM...TJT AVIATION...MAC FIRE WEATHER...BW
Area Forecast Discussion
National Weather Service Grand Forks ND
1021 PM CDT Wed Apr 12 2023 .UPDATE... Issued at 1019 PM CDT Wed Apr 12 2023 Updated to remove pops 06z to 09z in far NW cwa (Cando ND). Kept in 09z-12z and highly doubt anything then as flow supports keeping main mid level moisture west and northwest of our area. Tweeked temps a bit on Thursday a bit warmer as HRRR is trending warmer, though HRRR sfc temps may be a bit much with mid 70s Wadena and 60 in GF. UPDATE Issued at 659 PM CDT Wed Apr 12 2023 Updated sky cover to be a bit more cloudy in NW fcst area due to high clouds and then Wednesday daytime a bit more cloudy due to extensive high clouds and some mid clouds. Late tonight into Thu AM some hint at elevated shower chance in SE ND into MN 12z-15z Thu period. We have that covered in slight chc pops and that seems reasonable. && .SHORT TERM...(This evening through Thursday night) Issued at 231 PM CDT Wed Apr 12 2023 Currently, upper ridge axis is east of our area with southwesterly flow aloft setting up for the next couple of days, with a surface trough slowly pushing southeast out of the southern RRV and WC MN tonight. This surface trough is expected to stall to our south and southeast tonight into Thursday as southwesterly flow aloft and subtle upper height falls promotes poleward flow in the low levels. This poleward transport of low level moisture is beginning to be noticed via ALPW products within the southern and central Plains, even in spite of the cutoff low in the Southeast CONUS. Guidance like NAM3k and FV3 WRF showed some potential for elevated thunderstorms as early as late tonight into early morning Thursday sparked by LLJ/low level WAA overrunning the stalled boundary, however current placement of sufficient moisture content rooted near the LLJ does not appear to be enough to generate convection. Thus we did not include this into the forecast. There still could be some mid/upper level driven showers closer to the international border and/or northeast ND area as early as tonight. Some light showers will be possible during the day tomorrow as upper/mid residual moisture pushes over the area from the exit region of upper troughing over the Intermountain West, but is expected to be very light. Getting into Thursday night, most guidance indicates a mid level wave and LLJ development in the vicinity of the stalled boundary lee of this wave to spark scattered showers and thunderstorms out of SD into ND and NW MN. Some of this convection could produce heavy rain rates between 0.5-0.75 inch per hour, and some small, non-impactful hail can`t be ruled out given low freezing heights and marginal but present effective shear. Should there be training of convection, this could have local impacts to flooding potential should rain help rapidly melt lingering snowpack and/or fall on top of frozen/saturated ground. .LONG TERM...(Friday through Wednesday) Issued at 231 PM CDT Wed Apr 12 2023 Friday through Saturday, upper trough is expected to move east across our region. Initially on Friday into Saturday, shortwave energy will promote scattered to numerous rain showers, with embedded thunder possible. Similar to Thursday night, there is some potential for training of heavier rain rates Friday night into Saturday morning, this time favored in our southern and eastern areas. As the mid level wave moves through the area, there still remains some possibility for rain transitioning to snow Friday night through Sunday. Light snow amounts up to 4 inches remain possible, but impacts are mitigated due to warm surface temperatures especially during the day. Behind the departing trough Saturday, drier and relatively cooler conditions are favored as upper ridging starts to build into the Northern Plains into early next week. Confidence in the synoptic pattern degrades mid to late next week, with ensembles painting either a blocking pattern and upper ridging/dry conditions with milder temperatures back into the region, or progressive pattern with the upper ridging breaking east and more upper troughing nosing into the Plains which would bring more chance for precipitation. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 659 PM CDT Wed Apr 12 2023 VFR anticipated into Thursday morning with high clouds and a northwest wind 5 to 12 kts. Some chances for MVFR cigs to develop Thursday aftn as moisture increases. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...Riddle SHORT TERM...CJ LONG TERM...CJ AVIATION...Riddle
Area Forecast Discussion
National Weather Service Mobile AL
1008 PM CDT Wed Apr 12 2023 ...New UPDATE... .UPDATE... Issued at 1008 PM CDT Wed Apr 12 2023 Minor adjustments were made to expand the higher winds northward over the marine area and to expand the Gale Warning into the nearshore waters. The remainder of the forecast remains on track. /13 && .PREV DISCUSSION... /issued 713 PM CDT Wed Apr 12 2023/ ..New AVIATION... AVIATION... (00Z TAFS) Issued at 713 PM CDT Wed Apr 12 2023 Showers and thunderstorms over the Gulf will spread inland tonight, with coverage tapering off over the coastal counties late Thursday morning. VFR conditions gradually lower to MVFR near the coast later this evening and then over the remainder of the area tonight. IFR ceilings will also be possible across the area early Thursday morning. Conditions are then expected to improve to MVFR by late morning. East to northeast winds 5 to 10 knots increase to 10 to 15 knots tonight, potentially 15-20 knots near the coast, then become southeasterly Thursday morning and southwesterly Thursday afternoon as a surface low moves across the area. /14 PREV DISCUSSION... /issued 354 PM CDT Wed Apr 12 2023/ .New NEAR TERM, SHORT TERM, LONG TERM, MARINE... NEAR TERM... (Now through Thursday) Issued at 354 PM CDT Wed Apr 12 2023 An upper low centered over southwest Louisiana (and part of a Rex Block pattern) drifts slowly to near the border of central Mississippi/central Alabama through Thursday. An associated surface low appears to be located about 190 miles south of the mouth of the Mississippi River per the current satellite loop. The HRRR and 12Z GFS seem to have initiated fairly well with this feature, and deepen the surface low while taking it to coastal Mississippi by 12Z Thursday. The HRRR/GFS continue the surface low slowly northward into central Mississippi on Thursday, with some uncertainty as to how quickly the system weakens. Other guidance is in general agreement with this motion. A frontal boundary extending eastward from the surface low is expected to lift northward into the immediate coastal areas by 12Z Thursday, then continue northward through much of the remainder of the forecast area through the day. Current radar shows an area of rain across much of the marine area which is spreading into the southern portion of the area. A major uncertainty for the rest of the forecast period is how quickly a dry slot currently wrapping around the upper low impacts coverage of precipitation. After likely to categorical pops early this evening, have had to limit the higher pop values to balance the possible outcomes. Coverage is expected to decrease sufficiently over the southern portion of the area to go with chance pops Thursday morning, then pops decrease for much of the area through the afternoon. Shear values increase tonight with the 850 mb jet reaching 30-40 knots, then the 850 jet diminishes to near 20 knots Thursday morning. Instability values will be very low until early Thursday morning when SBCAPE values of 500-1000 J/kg will be realized near the coast. Similar SBCAPE values then develop over the eastern and central portions of the area on Thursday. While there does look to be an intersection of favorable shear and instability generally over the coastal counties late tonight into about mid Thursday morning, the potential for any strong storms, much less severe storm potential, is very murky (that would be underlined if possible) given the uncertainty with how quickly the dry slot will impact convection. Lows tonight range from the mid to upper 50s along and west of I-65 to the upper 50s/lower 60s east of I-65. Highs on Thursday will be in the 70s. A high risk of rip currents continues through the period. A high surf advisory remains in effect for beach areas until 1 pm Thursday. /29 SHORT TERM... (Thursday night through Sunday) Issued at 354 PM CDT Wed Apr 12 2023 An upper low will be located roughly over the border of central Mississippi/central Alabama early Thursday evening then slowly lifts northward and eventually breaks down to an open wave over the interior eastern states on Friday. A nearly co-located surface low weakens while following the system well off to the north, with progressively drier air flowing into the area in the wake of the system. Will have slight chance to chance pops for most of the area Thursday evening tapering off to dry conditions for Friday. A large upper trof meanwhile advances across the western states into the central states through Saturday and begins to strengthen Saturday night. An associated surface low lifts from the central Plains to the Great Lakes, and in the process brings a cold front through the forecast area late Saturday night into early Sunday morning. Deep layer moisture improves over the area as the front approaches, and will have slight chance to chance pops return to the forecast for Saturday. Have continued with chance pops for Saturday night, then slight chance to chance pops follow for Sunday morning as the front moves through the area. For Sunday afternoon, have gone with small pops over the eastern portion of the area for lingering precipitation in the wake of the front. Shear values look to be generally modest ahead of the frontal passage, and instability values appear to be generally limited except for possibly the western portion of the area Saturday afternoon into the early evening hours. At this time, the environment does not appear to support much of a risk for strong to severe storms but will continue to monitor. A high risk of rip currents Thursday night will be followed by a moderate risk for Friday and Friday night, afterwards a low risk is anticipated. Lows Thursday night range from the mid to upper 50s around and west of I-65 to around 60 further to the east. Lows Friday night range from the mid 50s well inland to the mid 60s at the immediate coast, then Saturday night will have lows in the lower to mid 60s. Highs on Friday and Sunday will be mostly in the mid to upper 70s, and highs on Saturday mostly range from the upper 70s to lower 80s. /29 LONG TERM... (Sunday night through Wednesday) Issued at 354 PM CDT Wed Apr 12 2023 Very dry deep layer air flows into the area in the wake of the cold front along with a surface high building into the area through Monday night. A surface ridge evolves along the northern Gulf coast by Tuesday which allows for a light return flow to ensue, but deep layer moisture looks to remain too limited to support consideration of pops and have continued with a dry forecast through Wednesday. /29 MARINE... Issued at 354 PM CDT Wed Apr 12 2023 A Gale Warning is in effect for the 20-60 nm portion of the marine area until 10 pm this evening for east winds 25 to 30 knots with frequent gusts to gale force. A Small Craft Advisory will otherwise be in effect until Thursday afternoon to allow enough time for winds and seas to subside. Will need to closely monitor trends this evening for possible expansion of the Gale Warning. /29 && .PRELIMINARY POINT TEMPS/POPS... Mobile 59 73 58 78 61 79 64 79 / 90 50 20 0 0 40 50 30 Pensacola 62 74 63 75 64 78 67 79 / 70 50 30 0 0 30 50 40 Destin 64 76 65 76 66 77 69 79 / 60 60 30 0 0 30 50 40 Evergreen 57 77 58 77 57 82 62 78 / 70 60 30 0 0 20 40 30 Waynesboro 55 70 55 78 58 81 61 75 / 70 70 20 0 0 30 40 20 Camden 55 76 57 76 57 83 62 76 / 70 70 40 10 0 20 40 20 Crestview 59 78 59 80 57 83 64 81 / 70 60 30 0 0 20 40 40 && .MOB WATCHES/WARNINGS/ADVISORIES... AL...High Rip Current Risk through late Thursday night for ALZ265-266. High Surf Advisory until 1 PM CDT Thursday for ALZ265-266. FL...High Rip Current Risk through late Thursday night for FLZ202-204- 206. High Surf Advisory until 1 PM CDT Thursday for FLZ202-204-206. MS...None. GM...Small Craft Advisory until 9 AM CDT Thursday for GMZ630>636. Gale Warning until 5 AM CDT Thursday for GMZ650-655-670-675. Small Craft Advisory from 5 AM to 1 PM CDT Thursday for GMZ650- 655-670-675. && $$ This product is also available on the web at:
Area Forecast Discussion...UPDATED
National Weather Service Twin Cities/Chanhassen MN
1044 PM CDT Wed Apr 12 2023 .UPDATE... Issued at 821 PM CDT Wed Apr 12 2023 Highs today reached at least the upper 80s across southern MN into parts of west central WI, with several locations touching 90. A cold front is sagging southeast across western and parts of central MN this evening, but will stall overnight and then lift back north Thursday. The thermal ridge responsible for today`s hot temperatures will settle a little farther north Thursday. A pocket of drier air will advect north and ground conditions will be drier after today`s heat. Therefore, areas a little farther north could have their shot at 90 Thursday, including the Twin Cities. If this were to occur, it would be the earliest 90 on record by a couple days. && .DISCUSSION...(This evening through Wednesday) Issued at 303 PM CDT Wed Apr 12 2023 KEY MESSAGES: - Critical fire weather conditions expected Thursday. - Speed of next system continues to slow down, with highs close to 80 still possible Friday over eastern MN and western WI before precipitation chances and cooler temperatures move in Friday night. - Best rain chances come Friday night into Saturday, with some mix with snow still possible Saturday night for any lingering precipitation. - Cooler but mostly dry through the middle of next week. It`s a beautiful summer day out there today as temperatures have been tracking well with our forecast, with record highs still expected to be toppled at MSP and EAU. We`ve seen a weak front/pressure trough slowly sag southeast into western through northeast MN this afternoon, but this boundary will stall out from roughly Redwood Falls to Duluth tonight. Along this boundary, winds will be light, with the potential for fog existing. However, this airmass is so dry, we are not anticipating widespread fog, even where we continue to see some lingering snow melt. Tonight, we`ll see the LLJ strengthen from eastern Neb into southern MN. The result of this LLJ is that it will push the boundary settling over our area tonight back north as a warm front for Thursday. As a result, forecast potential highs for Thursday took a step up today, with record highs again possible for MSP/EAU. The bigger issue here resides with the fire weather threat for Thursday. The HRRR in particular is very aggressive with mixing out dewpoints as the boundary lifts north and our moisture depth becomes shallower, with dewpoints mixing down to around 30 from south central and southeast up into east central MN and western WI. Resultant RH values on the HRRR are down around 15%. We didn`t go completely down that road, but did lower humidities for Thursday, with minimum RH values down around 20% thanks to the presence of temperatures again into the low to mid 80s. With that LLJ up into southern MN, winds are also looking stronger on Thursday as well, with gusts of 30 to 40 mph expected over south central MN up toward the Twin Cities. Given these low RHs and stronger winds, we issued a Fire Weather Watch for Thursday from Brown up to Anoka county, then over to Chippewa county in WI. For Thursday night, it will be another mild night, though precipitation is expected to continue along the periphery of the thermal ridge to the west and north of our area, with dry conditions expected in the MPX area through 12z Friday. The longer term period begins with a low pressure system entering the region from west to east, swinging a broad cold front across the area with showers beginning before sunrise on Friday in western Minnesota. This system and front will swing through the area slowly, with precipitation likely continuing in waves through early Sunday morning until the system ejects towards eastern Ontario later on Sunday. Broad synoptic scale forcing along the front will keep light to moderate rainfall across the area during a good portion of the event. The main question on everyones mind based on how ensemble and deterministic guidance has trended over the past couple of days, is how much snow do we end up seeing? The 12z deterministic runs of the GFS/ECMWF slowed the system down, keeping it around for about 8-12 hours longer and giving us a better shot at seeing snow during the last 1/3rd as cold air continues to wrap around behind the front. WPC & NBM continue to keep things as mostly rain with minimal snow, however a few GEFS/EPS members show up to 2-4 inches of snow across portions of eastern Minnesota to western Wisconsin, and based on the speed of the system this could even bump up a bit more. Bottom line is that we could see a slippery mess of snow late Saturday into Sunday especially, which should melt off fairly quickly given the mid April sun angle and temperatures returning to the 50s. Ridging returns behind the departing system to begin the week, with cooler temperatures especially compared to today and tomorrow as highs struggle to get out of the 50s. Wednesday we could see another smaller rain chance, however for now the forcing appears fairly weak and we are cut off from a significant amount of moisture to produce stronger or more widespread showers. The main story beyond Sunday will be in near to slightly below normal temperatures with our normals in the mid 50s by that point in April. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1044 PM CDT Wed Apr 12 2023 VFR through the period. A front has reached central and western MN, shifting winds northwest. The front will stall by 02Z, then lift back north Thursday with south winds returning area wide. KMSP...No additional concerns. /OUTLOOK FOR KMSP/ FRI...VFR. Chance -RA/MVFR late. Wind S 15-20G30 kts. SAT...MVFR. -RA likely, Wind NW 10-15 kts. SUN...MVFR. Chc -RASN. Wind NW 15-20G30 kts. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...Fire Weather Watch from Thursday afternoon through Thursday evening for Anoka-Blue Earth-Brown-Carver-Dakota-Faribault-Freeborn- Goodhue-Hennepin-Le Sueur-Martin-Nicollet-Ramsey-Rice-Scott- Sibley-Steele-Waseca-Washington-Watonwan. WI...None. && $$ UPDATE...Borghoff DISCUSSION...MPG AVIATION...Borghoff
Area Forecast Discussion
National Weather Service Seattle WA
836 PM PDT Wed Apr 12 2023 .SYNOPSIS...Generally dry conditions tonight into early Thursday before a weak front brings a chance for some showers over Western Washington. Drier conditions return Friday as a weak upper ridge builds into the region. A broad trough over the northeast Pacific will bring a return of active weather early next week. && .SHORT TERM /TONIGHT THROUGH SATURDAY/...A few showers have developed over Pierce county this evening but activity should be fading away over the next hour or two (per HRRR guidance). Otherwise, dry conditions elsewhere. Another chilly night on tap with overnight lows in the 30s. 33 Previous discussion...Current radar showing some light echoes...mostly along a NE to SW line along the east side of the Olympics, through Mason County and into the SE corner of Grays Harbor County. Another batch of intermittent echoes can be found over the northern two-thirds of the Cascade foothills. Nothing spectacular expected from either of these areas...mainly sprinkles or light showers at best. Remainder of the area is generally dry at the time of this writing with current satellite imagery showing increasing areas of clearing as clouds move southward along with the upper level low, now along the OR coast. While that clearing trend will extend into the evening by late tonight and the overnight period/early morning, will start to see clouds filter in as incoming weak frontal system approaches the coast. While the western half of the CWA may see some morning precip, the best chances for showers is expected to be during the late morning and afternoon before PoPs diminish during the evening. Most locations east of the Sound will only see PoPs in the 10-30 pct range /slight chance to low-end chance/ while the Olympic Peninsula and higher elevations of the Cascades will see higher chances /around 60 to 70 pct/. Both ensembles and deterministic models see this front weakening as it moves over the area and even though some locations may get rain, precip amounts will be relatively small...not getting above one- tenth of an inch in many locations. The front fizzles out Thursday night allowing for a weak upper level ridge to nudge into the area. This will help to keep the area dry throughout Friday. In fact, locations east of the Sound may see that dryness extend into at least Saturday afternoon as the next frontal system seems to get hung up along the coast before pushing in late Saturday afternoon/Saturday evening. Temps over the short term will see highs Thursday similar to those of today, generally in the upper 40s to lower 50s while the upper level ridge will give afternoon temps a shot in the arm with lower to mid 50s expected. These still fall short of normals however, as highs this time of year are typically in the upper 50s. Overnight lows tonight and Thursday night will generally range from the mid 30s to around 40 while lows Friday warm slightly, getting into the upper 30s to lower 40s. 18 .LONG TERM /SUNDAY THROUGH WEDNESDAY/...Once the aforementioned Saturday front moves into the area, this will trigger another round of active weather as another upper level low will camp out over the W coast of Canada, spinning system after system into W WA. As one would expect, while breaks and lulls can be expected during the long term, none of them persist long enough to be of any merit, nor do deterministic models find any agreement on when they might occur. Further blurring the picture are the vast array of ensemble solutions, although the ensemble mean keeps precip amounts generally less than or around one-tenth of an inch. If one needed to pick a singular day to plan outdoor activities, it seems like Sunday may be the day to avoid as the ensemble mean seems to be favoring that day for activity, although, as stated earlier, no particular date within the long term period can offer any prolonged dry conditions. Sunday will still see some benefit from the earlier dry period as highs that day look to be the warmest of the forecast period, with highs in the mid 50s to around 60. Otherwise, highs in the lower 50s can be expected. 18 && .AVIATION...North-northwest flow will develop this evening as a transient upper-level ridge builds over. VFR conditions will remain this evening, but low clouds look to develop overnight which could fall to the MVFR threshold. Can`t rule out a brief spell of patchy fog as well, particularly for spots like KPWT and KOLM under enough clearing prior to low cloud development but confidence is not high. Any low clouds that form should see a return to VFR skies later on Wednesday by 18z. However, a weak front will track into the area with light showers which under heavier precip could allow for additional brief instances of MVFR observations for Wednesday afternoon-evening. KSEA...VFR skies observed at the terminal this evening. However, low clouds will return early Wednesday morning with possible MVFR conditions between 12-16z. Winds look to turn south by 12z. 33/McMillian && .MARINE...Low level onshore flow will ease later tonight. Additional fronts will likely cross the waters Thursday and again over the weekend as the pattern remains active. Small craft advisory winds at least over the coastal waters with Saturday`s front. 33/McMillian && .HYDROLOGY...No river flooding expected in the next 7 days. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 6 AM PDT Thursday for Admiralty Inlet- Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. && $$
Area Forecast Discussion
National Weather Service Salt Lake City UT
359 PM MDT Wed Apr 12 2023 .SYNOPSIS...A storm system will move through the area late this evening through Thursday morning, bringing precipitation to northern Utah and dropping temperatures back to or below seasonal normals. High pressure will return for the upcoming weekend. && .SHORT TERM (Through 12Z Friday)...Watching a developing area of cumulus cloud in western Utah at this hour along a weak axis of instability ahead of the approaching mid-level trough and baroclinic zone. Analyzed 250 J/kg CAPE running well below forecasts from CAMs though ample sunshine and steep mid- and low- level lapse rates likely to make up for the lack. Largely missing any sort of moisture, as dewpoint depressions across the region remain large, which will be the main limiting factor in this evening`s convection. Anything that does form showers undoubtedly will produce relatively strong wind gusts in the vicinity. While analysis of the cold front tracks current model forecasts, noting that the latest HRRR has backed way off on the intensification of the front through northwestern Utah and reduced the pre-frontal winds and overall precipitation amounts in kind. Still expecting a brief period of moderate precipitation early Thursday morning as this feature transits the region, but if this latest run is a harbinger of what may come with the rest of the 00Z model suite, likely going to see total precipitation forecast decrease greatly along the Wasatch Front and northern mountains as a result. Additionally, a weaker cold front and more gradual arrival of cold air paired with less intense precipitation rates would shift a greater percentage of the total precipitation back towards snow rather than rain. Further complicating the precipitation type forecast is the strong synoptic lift, cold air aloft and convective potential stemming from it driving some period of graupel. In any case, likely to be a wet and possibly messy morning commute for portions of the Wasatch Front, and a much cooler afternoon on Thursday than we`ve had yet this week. Overnight lows Thursday will return to or just below seasonal norms behind the cold front. .LONG TERM (After 12Z Friday)...The extended forecast period remains largely unchanged as we creep into spring weather in the Great Basin region. Lingering precip from the storm system in the short term makes its way into Friday before giving way to a high pressure ridge. Ridging will bring back clearing skies and warmer temperatures, nearly 5-10F above climatological norms through the weekend and beginning of the coming work week. Uncertainty grows by midweek of a potential large scale low off the PNW coast that could bring widespread precipitation back to Utah. Friday morning the trough axis is expected to be through Utah thus shutting off any main precipitation. With 700mb temperatures remaining cold through the morning there is good potential for orographic processes to take over and squeeze any lingering low level moisture into some lingering snow showers over the northern Utah high terrain. This will later on give way to the ridge growing into the region, bringing more west/southwest flow aloft through the weekend that will rebound 700mb temperatures. Warming aloft will drive back clearer and sunny skies as temps settle to the ground, promoting spring like days through the weekend and into the beginning of the following week. Current grid values point towards the warmest days being Sunday/Monday with low 70s in most Utah valleys (60s Cache, 80s St. George). Current deterministic models favor a low pressure system deepening over the PNW coast that will grow into the region and drive precipitation over the state by the end of the extended period. Uncertainty remains in the exact timing of this trough to impact the CWA but ensemble members seem to help push the favorite towards a Tuesday/Wednesday arrival. This will also bring a cooling back to the area that will bring us back closer to seasonal norms. How much cooling this trough brings also leaves uncertainty in ptype but certainty will clear up in the coming days. && .AVIATION...KSLC...Varying winds from the southwest to northwest will last through roughly 06Z. With prevailing winds from the southwest aloft, any northwest flow would result in marginal low level wind shear. Broken to overcast ceilings will last through the overnight, with chances for rain then a rain-snow mix much of the morning. Ceilings and visibility will lower into MVFR or IFR range with precipitation around 13Z, lasting through the morning. .REST OF UTAH AND SOUTHWEST WYOMING...A cold front will track across northern Utah, reaching the urban corridor near sunrise. IFR or lower ceilings and visibility are likely with snow in far northern Utah, where other locations will mainly have rain or mixed precipitation. MVFR or IFR conditions are likely much of the morning for these locations. Dry conditions are expected throughout southern Utah. The cold front will reach there during the afternoon with southwest winds transitioning to northwest. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ Wessler/Selbig/Wilson For more information from NOAA`s National Weather Service visit...