Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 08/22/21

Area Forecast Discussion
National Weather Service Amarillo TX
612 PM CDT Sat Aug 21 2021 .UPDATE... Updated precip and temp trends based on how the storms are unfolding this evening. HRRR seems to be doing well with storm evolution tonight. Beat && .AVIATION... 00Z Issuance...All sites are currently VFR and look to remain so through the period. KAMA and KGUY may still see some thunderstorms in the vicinity over the next couple hours before they start dissipating for the evening. Winds will be southeasterly overnight and turning to southwesterly during the day tomorrow with some gusts around 20-25kts possible. Beat && .PREV DISCUSSION... /Issued 110 PM CDT Sat Aug 21 2021/ SHORT TERM... A surface low near Canyon TX had a stationary front extended northeast to the east central Texas Panhandle. This stationary front is expected to be the focus for initial thunderstorm development. Southwest flow aloft should carry the storms to the northeast. Some of the storms may become severe with large hail and damaging winds. Heavy rain may cause localized flooding. Thunderstorms will likely move out of our area or dissipate toward midnight. A thunderstorm will be possible across the northwest CWA on Sunday afternoon or evening. But will decide at the last minute on whether to insert this into the forecast. Not all models agree that there will be a thunderstorm in the northwest, so confidence is not very high at this time. Highs on Sunday will be close to a little above normal with readings in the upper 80`s to the mid 90`s. LONG TERM...Monday through Friday Upper high builds over the southern Plains states Monday through Thursday and should keep a dry pattern across the Panhandles. A shortwave trough over the southern Rockies late next week as the upper high breaks down will allow for the possibility of convection by late Friday and Friday night. The GFS hinting at the possibility for convection as early as Thursday afternoon and Thursday night mainly across the western or northwestern portions of the forecast area with the shortwave trough. Surface low over eastern Colorado and western Kansas Monday through Wednesday will deepen and allow for tightening of the surface pressure gradient resulting in gusty southerly to southwesterly winds. Surface low late next week across the central Plains states and central Rockies with surface trough extending south into New Mexico Thursday into Friday. Warmer and drier conditions expected next week with a few breezy to windy days. Schneider && .AMA Watches/Warnings/Advisories... TX...None. OK...None. && $$ 16/24
Area Forecast Discussion
National Weather Service Binghamton NY
946 PM EDT Sat Aug 21 2021 .SYNOPSIS... A chance for showers and some thunder lingers into the evening, then Hurricane Henri will bring additional periods of rain to parts of the region later Sunday into early next week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Late this evening mesoscale models even the brand new HRRR do not or poorly show the batch of showers across northern NJ into the NYC area. This batch of showers continues to move northwest into Sullivan and Pike counties. However, suspect this area of showers will become more diffuse as it tries to push further northwest as it gets farther away from the better forcing and dynamics. This batch of showers has resulted in some 1-2 inch rainfall totals further southeast toward NYC. For now, increased shower coverage and QPF a bit to account for recent trends. Later in the overnight, additional showers will be possible mainly across the Catskills. Otherwise, look for cloudy skies with some patchy fog likely given low level moisture and light winds. Temperatures will stay mild, only falling as far as the mid 60s to lower 70s. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY NIGHT/... 350 PM Update... While some of the model solutions, particularly the NAM/GFS, have trended slightly to the right with Henri`s landfall point, these same models continue to pull the system further to the west post-landfall, bringing significant rainfall further to the west as well. CAMS are generally further west both with landfall and with the axis of heavier precipitation, as has been the overall trend. A band of precip currently off the NJ coast associated with low/mid-level moisture convergence may bring some scattered heavier showers/thunderstorms into the Poconos by early Sunday morning. Otherwise, this band looks to redevelop later in the day across parts of Central NY, with the bulk of the Henri- related moisture holding off until late afternoon or early evening. Would not be surprised to see a significant precip-free area develop somewhere in the far eastern CWA late in the day, but it`s difficult to work this into the grids at this point given the range of possibilities. The heaviest rainfall with Henri looks to be Sunday evening into Monday, with north to northwest flow causing some enhancement along the north and west facing slopes of the higher terrain areas. Uncertainties crop back in again later on Monday. While Henri looks to do a sort of stall and loop before ejecting off to the northeast, a few CAMS execute this maneuver over the lower Hudson or even the Poconos, extending the heavy rainfall even further. Went a little long on the watch timeline in order to account for this possibility. Main impacts still are focused on flash flooding potential, but some flooding on the upper reaches of the mainstem rivers may also occur, lingering later into Monday or Tuesday. It would not take too much of an increase in QPF to throw a few more forecast points/gauges into flood stage. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Much of Wednesday remain dry amid upper level ridging, but additional showers and storms will begin to push in for the afternoon and evening with an influx of heat and moisture as our next system moves in. The cold front associated with this system will drag across NY and PA on Thursday, setting off more thunderstorms. Lingering instability will keep scattered showers in the forecast through the end of the work week. Otherwise, expect temperatures to stay quite warm through the midweek, peaking in the mid and upper 80s before temperatures turn more seasonal into Friday. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... VFR conditions expected at all terminals through 5z this evening. The showers this afternoon are coming to an end with the skies clearing over CNY but mid and high clouds are streaming into NE PA ahead of Hurricane Henri. ELM likely develops fog tonight with uncertainty in how early it will start to develop so a tempo group was put in between 5z and 7z. Greater certainty exist for IFR or worse between 7z and 12z. Other CNY terminals could get some patchy fog to develop around the terminals that could cause brief MVFR restrictions late tonight. Tomorrow, VFR conditions return in the morning once the fog lifts but MVFR conditions return in the late morning and early afternoon as some rain bands move into the region associated with the remnants of Henri. There is still uncertainty in how far NW the rain will make it so ITH and SYR did not have showers or restrictions put into this set of TAFs. Outlook... Sunday night through Monday...occasional showers/thunderstorms bringing restrictions. Some late night vsby restrictions due to valley fog, especially ELM. Tuesday/Wednesday...Mainly VFR conditions expected. May see early morning fog at ELM. Thursday...Restrictions possible in afternoon showers and thunderstorms. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...Flash Flood Watch from 6 AM EDT Sunday through Monday afternoon for PAZ040-044-047-048-072. NY...Flash Flood Watch from 6 AM EDT Sunday through Monday afternoon for NYZ046-057-062. && $$ SYNOPSIS...HLC NEAR TERM...HLC/MWG SHORT TERM...DJP/MPH LONG TERM...DJP/HLC AVIATION...AJG
Area Forecast Discussion
National Weather Service Caribou ME
910 PM EDT Sat Aug 21 2021 .SYNOPSIS... High pressure builds across the Maritimes into Sunday. Henri will approach southern New England tonight and move onshore in southern New England late Sunday. Henri will dissipate while it tracks across our region Monday into Tuesday. High pressure will build over the area Wednesday. Low pressure approaches the area on Thursday. && .NEAR TERM /THROUGH SUNDAY/... 9:10 PM Update: Two main updates at this time. A dense fog advisory was issued along the coast until 9 am Sunday morning. Web cameras around MDI were showing dense fog around the time of sunset, and it is likely to only become more widespread and dense with time. Also, a SCA was hoisted for the coastal waters starting on Sunday morning and running into Monday morning, mainly for swell from Henri. Otherwise, there were no significant changes planned at this time. The 8 pm advisory on Hurricane Henri indicated very little in the way of changes from the 5 pm advisory. Previous discussion: High pres will remain in place through Sunday. Henri will apch from the wrn Atlc overnight heading toward NYC/LI region on Sunday. his will play more of role for our region in regards to larger waves, swells and minor overwash at high tide along the coast later Sunday evening into Monday. More on that in the marine/coastal flood section. For tonight, convection threat is diminishing and will continue to have that trend into the evening. Showers will dissipate through the evening w/the loss of diurnal effects. The challenge then becomes low clouds and fog as llvl moisture gets affected northward from the Gulf of Maine. Kept the mention of fog in the forecast w/the best coverage across the central highlands down to the coast. Some of the high resolution guidance such as the HRRR, NAMNEST and RAP guidance show some light QPF pushing inland from the Gulf of Maine. The operational runs of the NAM and GFS much later in showing some light QPF most likely in the form of drizzle or light rain showers moving wnw from the Gulf of Maine. The ridge axis holds in across the northern 1/2 of the CWA to keep things dry. Mdl soundings do show deep llvl moisture trapped in below 850 mbs w/that light SSE flow and drier air above that layer, leading to more of a drizzle scenario. Therefore, added the mention of drizzle into forecast later tonight into Sunday morning. For Sunday, ridge axis shifts to the n w/the onshore flow setting up in earnest as 925 mb winds are expected to increase to 25 kts as Henri pushes to the NYC/LI area. Strong convergence setting up across the downeast region into the central highlands and w/the increasing winds at 925-850 mbs, showers/light rain threat to increase. Decided to follow GYX`S lead w/expanding the coverage & precip wnw into the Maine Central Highlands. Further n, ridge continues to hold keeping things dry. Low clouds hanging on a bit longer into late morning and w/the ESE wind could keep daytime temps down from what they have been over the last few days. Leaned in that direction w/temps at least 5 degrees cooler than they have been. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... By 00z Sunday, Hurricane Henri will be over southern New England, slowing down in forward speed as it pushes further inland. A plume of moisture out ahead of the system will lead to humid conditions across our forecast area Sunday night into Monday, with dewpoints in the 60s and PWATs surging above 2 inches. All of this moisture will support showers ahead of Henri, which will move into the Downeast region Sunday evening. Patchy fog will be possible across the forecast area Sunday night into early Monday morning due to the abundant moisture. After stalling over southern New England, Henri will begin to push eastward as the subtropical ridge strengthens on Monday. As the weakened system begins to approach our region, showers will increase in number from south to north across the forecast area. Winds will remain relatively light through the day on Monday, especially as a persistent marine layer reaching up to Dover- Foxcroft and Lincoln will provide enough stability to keep higher winds from mixing towards the surface. What remains of Henri will pass to the south on Tuesday, clearing off into the Canadian Maritimes. Showers will remain across the forecast area as the low passes, with the highest rainfall accumulations concentrated along the coast with up to an additional inch possible. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Skies will finally clear Tuesday night into Wednesday, but the lack of rain will not equate to a lack in moisture. A warm, humid airmass will remain through mid-week. Lingering moisture and diurnal heating will result in the chance for convective showers, especially Thursday afternoon. It will take a cold front Thursday night to clear the humidity and bring drier conditions across the entire forecast area. This cold front will be our next chance for widespread rain. Drier weather is expected heading into next weekend. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... NEAR TERM: VFR across the northern terminals to gradually drop back to MVFR later tonight and then could go down to IFR by early morning on Sunday. MVFR for KBGR/KBHB this evening dropping to IFR/LIFR overnight with dense fog possible at times at KBHB through mid morning Sunday. ESE wind < 10 kt. For Sunday, IFR/MVFR for all terminals in the morning w/improvement across the northern terminals to VFR by mid morning. KBGR and KBHB will see a gradual improvement to MVFR by late morning. ESE winds 10 kts. SHORT TERM: Sun night - Tues...MVFR/IFR likely across southern terminals with the approach of Hurricane Henri. Northern terminals will fall to MVFR overnight Sunday night as showers move northwards. Light SE winds will shift S to SW on Tuesday. Tues night - Wed night...VFR across all terminals. Light W winds. && .MARINE... NEAR TERM: Seas are expected to gradually build for this term reaching 5-7 ft by Sunday afternoon w/12-14 second periods leading to large swells. ESE winds increasing to 10-15 kt w/gusts 20-25 kt later in the day over the outer zones. In collaboration with WFO Gray have issued a SCA starting Sunday morning for the coastal marine zones. SHORT TERM: Seas will range from 6 to 8 feet late Sunday into Mon morning before dropping below SCA levels Mon night. Remnants of Hurricane Henri will cross the waters late Monday night into Tuesday. Brief wind gusts approaching 25kts during the period. Visibilities will be reduced in fog as humid air remains over the water through the end of the week. && .TIDES/COASTAL FLOODING... High astronomical tides and TS Henri may bring minor coastal flooding issues around the time of high tide Sunday night and Monday night around midnight. Attm, given the latest setup, some minor splash over is possible, but w/the long period swells, and high surf, the risk of rip currents and big breakers hitting the coast could be an issue. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...Dense Fog Advisory until 9 AM EDT Sunday for MEZ029-030. MARINE...Small Craft Advisory from 8 AM Sunday to 8 AM EDT Monday for ANZ050-051. && $$ Near Term...CB/Hewitt Short Term...AStrauser Long Term...AStrauser Aviation...CB/Hewitt/AStrauser Marine...CB/Hewitt/AStrauser Tides/Coastal Flooding...Farrar/Hewitt/CB
Area Forecast Discussion
National Weather Service Grand Junction CO
546 PM MDT Sat Aug 21 2021 .SHORT TERM...(Tonight through Sunday night) Issued at 248 PM MDT Sat Aug 21 2021 Isolated to scattered storms developed this morning further south than most if not all of the hi res CAM models indicated across southeast Utah and southwest Colorado. These storms tracked northeast over the central valleys by mid to late morning, with a few rumbles of thunder and light to moderate rain, much to the surprise of many. However, these storms were very quick moving and shallow with a dry sub cloud layer as indicated by the 12Z GJT morning sounding and forecast model soundings. As a result, precipitation amounts were very light (a few hundredths to a tenth of an inch at best measured at gauges and estimated by radar). So flooding concerns are minimal at this time and not much a concern. After doing a deep dive in the mesoanalysis to see what is sustaining this convection, looks like steep low level lapse rates and an axis of effective bulk shear ahead of the shortwave trough that is currently moving through the Pacific NW and northern Great Basin. Makes sense. An 80 kt jet streak associated with this shortwave trough will track across northeast Utah and northwest Colorado tonight, helping sustain convection across the north overnight into Sunday morning before dissipating by sunrise. Temperatures have also been trending much cooler than guidance due to the increase in cloud cover and shower activity that models weren`t picking up on as well, so backed off the high temperatures today as well as the next few days as the warming trend seemed a bit too quick given recent trends. Sunday will provide much drier conditions behind this shortwave trough with westerly flow up north helping pull more smoke in from the California wildfires. A bit of good news in regards to the smoke though is the latest HRRR smoke model seems to push most of the smoke out of the central and southern areas and keeps it concentrated across the north, thanks to more of a southwest component to the upper level winds across that portion of the CWA. While that is good news for areas along and south of I-70, not so good news for those locales further north towards the Wyoming border. Temperatures will be a bit warmer on Sunday compared to today, but still around 5 degrees below normal. .LONG TERM...(Monday through Saturday) Issued at 248 PM MDT Sat Aug 21 2021 Eastern Utah and Western Colorado predominately fall under southwesterly flow through the long term period. The region will remain sandwiched between a broad rotation of high pressure over the Southern Plains and lower heights anchored to the PacNW for several days. A series of shortwave troughs rippling through the PacNW low may generate a nudge of lift and instability aloft, favoring isolated showers over higher terrain each afternoon. However, the remaining forecast area will indulge in a warming and drying period, with only increased surface winds from said disturbances. High temperatures will climb from the low 90`s across valley floors on Monday to nearly triple digits by mid-week in some remote desert areas of southeast Utah. Meanwhile, PWATs drop to around 0.25" to 0.5" across the Western Slope by Wednesday. Forecast soundings reveal an inverted V signature deepening each day, which will limit the showers that do try to wring out precipitation from reaching the ground and thus, further enhancing surface winds. In addition, this atmospheric profile is favorable for deep, boundary layer mixing, which can transport some of the stronger momentum aloft down to the surface. Therefore, near critical RH levels and increased winds will increase the concern for localized fire weather conditions each afternoon; though, fuels may very well be a limiting factor (considering all of the rain we`ve received earlier in the week). Model consensus tries to push the stagnant low inland by the middle to end of the week, which will suppress the mid level high to the southwest. This synoptic set up could be more favorable for the CWA to tap into Sub Tropical moisture, though, confidence in the strength of the plume and its trajectory remain low, attm. Looking ahead to next weekend, ridging slides back into the Western CONUS, which would return a dry and warming trend back across the Western Slope. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 546 PM MDT Sat Aug 21 2021 Isolated to low end scattered showers and thunderstorms will continue this evening, mainly over the higher elevations in the north. However, a disturbance passing north of the region overnight may sustain some activity across the northern border zones late. There is little chance this activity will impact TAF sites however, so left VFR conditions at all TAF sites. LLWS is expected as winds diminish this evening and will impact KHDN, KEGE, KASE, KGUC and KTEX through sunrise. Breezy southwest winds develop for most sites again Sunday afternoon. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...None. UT...None. && $$ SHORT TERM...MDA LONG TERM...ERW AVIATION...NL
Area Forecast Discussion
National Weather Service Gray ME
1154 PM EDT Sat Aug 21 2021 .SYNOPSIS... Warm and humid conditions will continue through Monday as Henri moves up the coast and weakens over southern New England tomorrow and tomorrow night. The effects on our region will be occasional showers, possibly heavy, gusty winds at times especially in showers, along with building surf. Thereafter, summery weather continues through the week with mainly dry weather, although a few rounds of scattered showers and thunderstorms cannot be ruled out. && .NEAR TERM /TONIGHT/... 1155 PM Update... Incorporated a fair amount of the 00Z HRRR into a refresh of temperature and dew point trends through tonight and tomorrow. With onshore flow and widespread clouds I don`t expect temperatures to warm much tomorrow, except for over the upper Connecticut River Valley with more breaks in the clouds... and some downsloping. 855 PM Update... Issued a Dense Fog Advisory along the coast through tonight with a strong onshore flow bringing the fog bank in, shown well by satellite imagery... as well as crashing ceilings at this hour. Brief period of dense fog have already been observed, so anticipate more widespread dense fog to develop tonight along the coast. Will be monitoring inland trends for a possible expansion. 650 PM Update... Only a few minor tweaks to temperature and sky trends for now, mainly to go harder with the marine layer for the remainder of the evening and tonight. Satellite and observations are showing crashing ceilings into tonight with stratus over taking most of the region south and east of the mountains. Will be monitoring for dense fog development in the coming hours... in case a dense fog advisory needs to be issued along the coast. Previously... Scattered convective showers will continue in the interior into the early evening as very moist easterly low level flow gently upslopes. This activity should wane this evening. Thereafter, low stratus will become ubiquitous along with areas of fog. It is not out of the question that we will need a dense fog advisory for portions of the coastal plain as well as central ME. Otherwise, some drizzle will be possible as well but overnight temperatures will remain very warm. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... Henri makes landfall on Long Island NY or the New England south coast during the day on Sunday. While it approaches, a northeasterly low level jet will increase across southern zones, to about 50 kt around 900 mb. While mixing heights will be relatively low on Sunday, some gusts of 30-40 MPH will be possible across southern zones starting in the morning on Sunday. The most susceptible area will be the Monadnocks of NH, with winds downsloping into the lower elevations such as Keene. Several CAMs are in good agreement that a northward moving feeder band will quickly move from south to north across the forecast area during the day with a risk of very heavy downpours for a short period of time. As far as timing goes on that, there is general agreement that it will move into southernmost NH between 8 and 10 am, then advancing quickly northward to near a KLEB-KPWM line between noon-2 pm, then likely weakening after that. A quick half inch to inch of rain will be possible with this feature along with some gusty winds that could be mixed down. Other than that, fog and some drizzle remains on the coast during the day with occasional showers. The day should not be a complete washout, however. Went with isold thunder in the south on Sunday, but have left thunder out of the forecast at this time elsewhere due to very poor lapse rates and very high freezing levels. Non-zero chance of a tornado across southernmost zones in accordance with SPC marginal risk, but at this time this far north, it appears that low level thermodynamic profiles will not be conducive. Fog, drizzle, and occasional heavy passing showers expected Sunday night with attendant risk for localized flash flooding, especially across southern NH but winds do not look to be an issue at this time. && .LONG TERM /MONDAY THROUGH SATURDAY/... Focus on long term is the continued influence of TC Henri and then a return to the heat. Expect the stable boundary layer over much of the area starting the day off Monday with some fog/drizzle in the midcoast areas with the tropical airmass in place. Clouds could help hold temperatures down in the 70s for much of the region, with the exception of s NH where highs could creep into the 80s away from the stable air near the coast. Basing the forecast of the NHC 2PM forecast for TC Henri, it is projected to slowly lift across southern NH into southern ME on Monday Night into early Tuesday morning. Have raised pops accordingly and mention flood concerns in the hydro section below. As the low pushes east on Tuesday NW flow will develop and we will see drier air filter into the region. Some clouds will likely linger in the north, but for much of the area some sun should allow temperatures to shoot quickly back into the 80s. Despite drying in the mid/upper levels the surface will remain somewhat muggy. For Wednesday temperatures will be even warmer with much of the area in the mid to upper 80s, with ongoing dewpoints in the 70s. Expect diurnally driven convection, but without much shear for support don`t see potential for any organized storms. Finally the shift in the upper level pattern comes late in the period with the cold front on Thursday. There will be some scattered showers and thunderstorms with a notable drop in temperatures and humidity for the end of the week into the weekend. && .AVIATION /04Z SUNDAY THROUGH THURSDAY/... Short Term...IFR or lower tonight in fog and low clouds, especially on the coastal plain and central ME terminals. Areas of fog may be dense. The first rain bands from Henri will begin to affect the area on Sunday with periods of squally rains. While conditions may lift to MVFR for a time away from the coast during the day Sunday, IFR will prevail. LIFR conditions expected Sunday night. Long Term...The tropical airmass over the area will support a combination of low clouds, fog, drizzle Monday morning followed by moderate and occasionally heavy rainfall by Monday night as the remnants of TC Henri pass over the terminals. Moisture will erode quickly on the backside of the system as it moves east of the area on Tuesday, which should help improve ceiling to VFR in NW flow. && .MARINE... Short Term...Onshore easterly flow develops and strengthens through Sunday as Henri approaches from the south. A small craft advisory has been issued for the coastal waters for Sunday into Monday. Long Term...S swells will continue in the long term as the core of TC Henri remains inland. Seas will be 4 to 6 ft mainly from a 11sec swell from Henri. The S direction of the swell may be reduced along NH and east facing zones in southern Maine due to some by blockage from the Cape. The winds should remain below SCA as cool stable marine air remains in place. Based on NHC latest track, the low will move over the Gulf of Maine Tuesday morning as it moves east. The expectation is that the intensity will have significantly diminished while inland and will not pose a marine wind hazard as it moves by the local waters. Winds will become NW behind the system which will help dampen the lingering s swells to below 4 ft by later on Tuesday. && .HYDROLOGY... High pressure from the north push into the area slightly reducing the PWATs down to 1.75". As TC Henri lifts north the moisture surge will spread into the region with PWATs rising to 2.25" along southern ME/NH by this time tomorrow. As TC Henri lingers to the southwest on Sunday and Monday, scattered showers and thunderstorms are expected to develop over the area with pockets of torrential rainfall. Given how weak the forcing is showers and thunderstorms will be closely tied to the diurnal cycle, with peak coverage this afternoon/evening. At this time concern is not high for widespread heavy rainfall, but these locally high amounts could add up if repeated areas are impacted. The increased support in the upslope regions of the Monadnocks and White Mountains are of particular concern for repeat development. The final track of TC Henri could also bring a swath of moderate to heavy rainfall, with the latest forecast bringing it over S NH and ME. RFC/WPC QPF forecasts attempt to highlight the rainfall enhanced by upslope, and do well for an overall rainfall assessment. However we recognize there could easily be pockets of locally higher amounts that could lead to flash flooding. Soil moisture percentiles remain high in S NH due in part to Fred`s passage a few days back. For now river flooding appears to be a low threat as most rivers remain at or below normal streamflows. Some lakes/reservoirs in S NH where heavy rains have fallen over the last 6 weeks remain high, but there should be enough storage to handle this storm. All of these factors combine to support the Excessive Rainfall highlighting a slight risk mainly over NH up to the White Mountains region. && .TIDES/COASTAL FLOODING... Prolonged onshore flow is expected to increase tonight through tomorrow out of the NE before switching to the SE by late Monday. Looking at the ESTOFS/ETSS/PETSS guidance all models keep storm surge values around .8 to 1.2 feet through this period. Potential exists for the models underdoing the surge on Monday due to the prolonged nature of the onshore flow and multiple tide cycles. The good news is the peak HAT cycle will occur tomorrow night with slightly lower tide cycles heading into Monday. This should keep TWL just below minor flood levels. Its possible that Hampton Area could touch 11ft tomorrow night. In addition, near shore seas will be building to near 5 feet by high tide tomorrow night, so splash-over could be an issue on vulnerable coastal areas. Waves will still elevated on Monday along with water levels, so minor splash-over and beach erosion can`t be ruled out on the Monday night high tide, but the likelihood looks much lower. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Dense Fog Advisory until 9 AM EDT Sunday for MEZ023>028. NH...Dense Fog Advisory until 9 AM EDT Sunday for NHZ014. MARINE...Small Craft Advisory from 8 AM Sunday to noon EDT Monday for ANZ150-152-154. && $$ UPDATE...Casey NEAR TERM...Ekster SHORT TERM...Ekster LONG TERM...Jamison
Area Forecast Discussion
National Weather Service Wichita KS
1028 PM CDT Sat Aug 21 2021 .SHORT TERM...(This evening through Tuesday night) Issued at 225 PM CDT Sat Aug 21 2021 Bottom line up front: A slim chance of late afternoon storms along the KS/OK border this afternoon. A chance of widely scattered elevated convection after midnight. Then a return of very warm temperatures to start the week. Convective outflow from last nights complex of storms over southern KS pushed south into central OK, but has all but washed out by this afternoon. Main synoptic cold front is making slow progress thru the Flint Hills into northern OK and SE KS at this time, with lower 70s surface dewpoints still pooling just southeast of the boundary along the KS/OK line in SE KS. Latest SPC meso page shows SBCAPE values of 3000-3500 J/kg pooling just south of the border across northern OK. For late this afternoon into early this evening, think convergence and afternoon heating along the stalling cold front will be enough for scattered storms to develop across northern OK, as inhibition is lost and this area becomes uncapped. There appears to be a slight chance that a few storms may develop close to the KS/OK border as well, so will leave some slight pops in for this chance for the late afternoon into the early evening. Bulk shear of 25-30kts and SBCAPE values of 3500 J/Kg may lead to a few strong to severe storms, with damaging winds being the main concern. Most of the high rez model solutions keep the bulk of the afternoon convective chances further south in nrn OK. Low level moisture transport and warm advection really gets ramped up across northern OK and southern KS late this evening and overnight, which will lead to the frontal boundary lifting back north as a warm front late tonight. This will probably lead to scattered elevated convection developing across portions of southern KS after midnight as mid level lift increase, with the convection lifting NE across most of the forecast area through early Sun morning. High rez cam solutions only show isolated elevated convection developing late tonight, with the RAP showing the best moisture transport focused in areas west of the forecast area. Still plan on going with a slight chance pops for this chance. Elevated instability of 1750-2000 J/KG, lifting north back across the forecast area may lead a few strong storms. SW flow and a lee side trough reestablishing itself along the front range, will lead to very warm and breezy conditions for Sunday, Monday and possibly into Tue, as convective chances shift back north into Neb. 1000-850h partial thickness values suggest max temps will climb back into the mid to upper 90s for Sun and the upper 90s to near 100 for Mon/Tue. The breezy conditions will help surface dewpoints mix out for the afternoon hours, keeping Wet Bulb Globe Temps (WBGT) and heat index values below heat advisory values. Most of the convective chances will stay well north of the forecast area through Wed. Could see some convection try to get going across NW KS on Tue evening, but as this convection moves east, it will run into warmer mid level temperatures, which will squash the convection as it moves into central KS. Ketcham .LONG TERM...(Wednesday through Saturday) Issued at 225 PM CDT Sat Aug 21 2021 Will keep some low pops across central KS for the Wed evening and Thu, as a frontal boundary tries to sag south into nrn KS, but confidence is low. Confidence in warmer than normal temperatures remaining across the region is increasing. Ketcham && .AVIATION...(For the 06Z TAFS through 06Z Sunday night) Issued at 1027 PM CDT Sat Aug 21 2021 Scattered showers and storms will affect portions of southeast Kansas overnight. Otherwise VFR conditions will prevail for the next 24hrs across the region with easterly winds veering out to the south and increasing on Sunday. && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 71 95 74 99 / 10 10 0 0 Hutchinson 69 95 74 99 / 10 10 0 0 Newton 69 92 73 97 / 10 10 0 0 ElDorado 70 92 74 96 / 10 10 0 0 Winfield-KWLD 72 95 73 99 / 30 10 0 0 Russell 67 97 74 100 / 10 10 10 10 Great Bend 67 94 73 96 / 10 10 0 0 Salina 67 95 75 99 / 10 10 10 0 McPherson 67 92 73 96 / 10 10 0 0 Coffeyville 73 94 74 98 / 30 10 0 0 Chanute 72 92 75 96 / 30 10 0 0 Iola 70 91 74 96 / 20 10 0 0 Parsons-KPPF 72 92 74 97 / 30 10 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...Ketcham LONG TERM...Ketcham AVIATION...CDJ
Area Forecast Discussion
National Weather Service North Platte NE
709 PM CDT Sat Aug 21 2021 .SHORT TERM...(This evening through Sunday night) Issued at 341 PM CDT Sat Aug 21 2021 Isolated POPs are in place tonight and Sunday. The focus tonight will be increasing warm air advection from a low level jet and a weak subtropical disturbance moving northeast out of Colorado. This could produce isolated showers or thunderstorms across swrn and ncntl Nebraska tonight. Another chance for storms develops Sunday afternoon and Sunday evening affecting ncntl Nebraska and perhaps parts of swrn Nebraska. This storm chance is associated with an upper level disturbance moving through Oregon this afternoon. The disturbance will move through the Dakotas Sunday. The disturbance should send a dryline and weak cold front through wrn Nebraska during the afternoon. The models appear to triggering storm activity along the dryline - east of highway 83 in the afternoon. Winds aloft are very strong...50-75 kts at the h500-300mb level and moisture robust across ncntl Nebraska where PWAT will approach 1.5 inches. The uncertainty in the POP forecast revolves around upper level support, low level focus and the very strong shear. For this forecast, the weak forcing aloft, modest focus and very strong shear should limit storm coverage to isolated. SPC suggested a severe storm risk for Sunday and this is certainly warranted given the instability and shear expected to develop. Wind and hail would appear to be the primary hazard. WPC suggested marginal excessive rainfall and this is appropriate for 1.5 inches of precipitable water predicted by the NAM and RAP models. The temperature forecast uses the model blend plus bias correction for lows in the 50s and 60s tonight and Sunday night. Highs in the 80s to lower 90s are in place Sunday. The temperature forecast Sunday might be too warm given the recent rains but it is in the middle of 12 models. .LONG TERM...(Monday through Saturday) Issued at 341 PM CDT Sat Aug 21 2021 The models are in very good agreement building an upper level ridge across Texas north toward Nebraska early this week. Winds aloft at h500-300mb will remain fairly strong at 20-25kts at h500 and 40-50 kts at h300. This belt of fairly strong westerlies and at times southwesterlies, could potentially produce strong to severe storms. The ridge will retreat south Wednesday with the approach of and upper level trof moving through Pacific Northwest. The best chance for thunderstorms arrives Wednesday into Thursday. Warm air will build into the region Sunday and remain in place through next Saturday. H700mb temperatures rise to 12C-15C during this time supporting highs in the upper 80s to lower 90s Monday and Tuesday. A back door cold front cools highs back into the 80s Wednesday and beyond. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 658 PM CDT Sat Aug 21 2021 A few showers and TSTMS are expected to develop late tonight as a southerly low-level jet develops. This will also lead to LLWS across the area through the mid-morning hours Sunday. Winds will be gusty at times from the south-southeast. && .LBF WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...CDC LONG TERM...CDC AVIATION...Taylor
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
900 PM EDT Sat Aug 21 2021 .SYNOPSIS... An upper-level low will remain overhead through the weekend, while Henri tracks northward toward Long Island/New England. High pressure will build in for the first half of the week before a cold front approaches from the north during the second half of the week. && .NEAR TERM /THROUGH SUNDAY/... 9:00 PM UPDATE: Current satellite observations depict an upper low directly over the forecast area, particularly over our western zones. This has re-invigorated convection over the higher terrain, even now in the absence of daytime heating. A few storms have gotten fairly tall, but have failed to become severe thus far. The bigger concern is going to be for some isolated instances of flooding/flash flooding, as storms struggle to move much in the absence of significant steering flow. Do expect this to gradually taper off over the next few hours however, as stabilization continues. So, will maintain an isolated severe/flash flood threat until radar activity tapers off. PREVIOUS DISCUSSION: As we move into the overnight hours, attention will turn to our north, where an inverted surface trough is expected to develop over PA/NJ to the northwest of Henri/ahead of the upper low overhead. Model guidance indicates that a very heavy band of precipitation may form within this inverted trough, but thankfully CAM guidance has also been consistent run to run in keeping this heavier precipitation just to the north and east of our forecast area. However, this feature does bear watching as we move through the rest of the day into tonight, since it could potentially impact northeast MD if its location were to trend further southwest over time. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... 9:00 PM UPDATE: With the latest runs of the HRRR, now including the 18z extended run, not much has changed in regards to our forecast for tomorrow. Still far too much uncertainty at this point to know for sure how much rain northeast Maryland sees tomorrow. The 18z run throws a spiral band down through northeast MD early tomorrow morning, then brings in wrap-around precip late tomorrow night. Should this occur, we would likely have some flooding issues, albeit isolated outside of the Baltimore metro. Will have to monitor closely as the overnight runs come in to see if some consensus is formed on the evolution of things tomorrow regarding Henri. Think as the 00z guidance trickles in, perhaps a decision can be made on any flooding headlines. PREVIOUS DISCUSSION: The aforementioned upper low will continue to reside overhead during the day tomorrow. Meanwhile, Henri will continue to track toward the north, likely making landfall on Long Island some time tomorrow afternoon. Exactly how Henri interacts with the upper low will have a strong influence on our forecast for tomorrow, and an atypical amount of spread exists in the forecast for tomorrow afternoon into tomorrow night, especially across northeastern MD. Some members of the 12z HREF (most notably the HRRR and WRF-ARW members) draw Henri much further south than other model guidance, backing heavy rain into northeastern MD by tomorrow evening. If this type of scenario were to play out, some localized instances of flooding can`t be ruled out. Thankfully, flash flood guidance is relatively high over northeastern MD outside of Baltimore, so we may avoid hydro issues as long as the heaviest rain stays out of Baltimore. These HRRR and WRF-ARW solutions are outliers at the moment, so it is very possible that the entire forecast area avoids heavier rain, with just some lighter rain across northern MD tomorrow afternoon into tomorrow night. Elsewhere, a stray shower or thunderstorm can`t be ruled out tomorrow afternoon or evening, but areal coverage of storms isn`t expected to be high and the storms aren`t expected to be intense. Any precipitation associated with Henri should exit off to our north and east by daybreak Monday. The upper low will also depart off to our north and east during the day Monday, but a warm and humid airmass will still remain in place in its wake. As a result, a stray afternoon or evening thunderstorm can`t be ruled out in response to daytime heating. With limited instability and weak flow, any storms that do form aren`t expected to lead to any hazardous weather. Highs on Monday will return to near normal, with highs in the upper 80s for most. && .LONG TERM /TUESDAY THROUGH SATURDAY/... High pressure returns to the region for the bulk of the week, with hot and humid conditions and spotty afternoon thunderstorms. Hottest and driest day looks likely to be Tuesday in the wake of Henri with best compressional heating as the system moves away and high pressure builds in. This wanes Wednesday and Thursday as high pressure, initially just to our west, shifts east and we start to get a stronger flow of moist tropical air back northward across the region. By Friday into Saturday, we`ll be watching a front approaching from the north, which may start to focus the storm development Friday, then may stall in the area Saturday. Still lots of uncertainty with this, but overall looks like a stormier and cooling trend as we head into next weekend. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... Prevailing VFR conditions are expected through Monday. Thunderstorms will be possible each afternoon, but areal coverage of storms isn`t expected to be high. A steadier period of rain associated with the outer fringe of Henri may potentially work into MTN or BWI tomorrow evening, but confidence in this occurring remains low. Winds will be light out of the east or north today through tonight, before becoming light out of the west to northwest tomorrow through Monday. Generally VFR Tuesday through Thursday under high pressure. Main concern is for patchy early morning fog and isolated to scattered afternoon/early evening thunderstorms. Best risk of both will be at MRB and CHO. The risk likely is lowest on Tuesday with a gradual increase in chances through Thursday. && .MARINE... Sub-SCA level winds are expected through Monday. Winds will be light out of either the east or north today, before becoming light out of the west to northwest tomorrow and Monday. An MWS may be needed this afternoon if a storm were to move over the waters. Light winds likely prevail over Tuesday thru Thursday under high pressure. Only concern would be for an isolated thunderstorm reaching the waters. The risk likely is lowest on Tuesday with a gradual increase in chances through Thursday. && .TIDES/COASTAL FLOODING... Latest guidance has continued to keep tidal anomalies lower. Most sites with the exception of DC Waterfront and Annapolis will remain below action stage over the next few days. Otherwise, not anticipating any minor tidal flooding issues over the next few days. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...None. MD...None. VA...None. WV...None. MARINE...None. && $$ SYNOPSIS...KJP NEAR TERM...CJL/KJP SHORT TERM...CJL/KJP LONG TERM...RCM AVIATION...RCM/KJP MARINE...RCM/KJP TIDES/COASTAL FLOODING...BRO
Area Forecast Discussion
National Weather Service Medford OR
856 PM PDT Sat Aug 21 2021 .UPDATE... An update has been sent this evening to refine some forecast elements based on newer data. Edits were made to sky cover through Sunday evening, to smoke in the present weather grids through Monday afternoon, and temperatures through Monday afternoon. && .DISCUSSION... The thick smoke that has periodically plagued the Rogue Valley from Medford to Ashland and surrounding areas in recent days has shifted it`s focus northeastward this evening. Diamond Lake Resort`s PurpleAir sensor was indicating an instantaneous AQI of 543 at last check. Poor air quality extends from that area southeastward into the Klamath and Tule Lake Basins. Overnight into the morning the HRRR Smoke Model suggests that the smoke from the fires in the Umpqua Basin will split to areas on both sides of the Cascades again, likely resulting in some spill over into the Rogue Valley by morning. On Sunday afternoon this is likely to flush eastward again, but an elevated smoke deck from the California fires is expected to linger overhead through the day over SE Jackson County. This is likely to keep temperatures below guidance in many areas affected by the smoke, once again. Otherwise, the forecast remains on track for little change in the day to day weather through about the middle of next week, though there is an upper level shortwave trough that will ride through Tuesday into Wednesday that bears some watching for stirring things up a bit more then. ~BTL && .AVIATION...22/00Z TAFs...Along the coast and just offshore, VFR conditions will continue into early this evening, then marine stratus will once again form between 3-5z north of Cape Blanco with MVFR ceilings to start, then lowering to IFR tonight into Sunday morning. The marine stratus will gradually burn off with ceilings improving to MVFR between 16-18z, then VFR around midday at North Bend. Inland west of the Cascades, VFR ceilings will continue into this evening with marine stratus forming and/or pushing into the Coquille Basin later this evening, then into the Umpqua Basin and Illinois Valley later tonight with MVFR ceilings at Roseburg towards daybreak Sunday. Medford is expected to remain VFR through the TAF period. There is a slight chance visibility could lower to MVFR late tonight into Sunday morning, but confidence is not high enough to include it in the Medford TAF. East of the Cascades, smoke from the fires in Douglas County will result in MVFR visibility at Klamath Falls through Sunday morning, then winds are expected to shift southwest resulting in improve visibility Sunday afternoon. -Petrucelli && .MARINE...Updated 120 PM PDT Saturday, 21 August 2021...A thermal trough along the southern Oregon Coast will persist into early next week with moderate to strong winds (strongest during the afternoon and evening hours) and steep wind driven seas, especially south of Cape Blanco. The remnants of a front will likely briefly weaken this pattern Tuesday into Wednesday. Then then thermal trough will likely restrengthen late Wednesday into Thursday and persist into the weekend. /BR-y && .FIRE WEATHER...Updated 130 PM PDT Saturday 21 August 2021...An upper trough is moving through our area today. This trough produced a strong marine push last night and the effects of this push are still being felt across the area in the form of elevated humidities and relatively cool temperatures. We will also see some gusty west- northwest winds later this afternoon and evening as stronger winds mix down from aloft. Stratus will surge onshore again tonight but to a slightly lesser degree than last night. This will result in good humidity recoveries again tonight. However, the air mass is beginning to dry out aloft, so the higher elevations of western Siskiyou County will see only moderate recoveries tonight. Weak upper troughiness remains over the PacNW tomorrow through at least Thursday, and this will promote near normal temperatures and humidities, typical diurnal winds, and no threat for precipitation. Guidance generally suggests a warming and drying trend late next week into next weekend as a ridge builds over the area. However, guidance is split as to the strength of this ridge and the resulting warming. However, we do expect to warm to at least a little above normal by next weekend with the potential for increasing offshore (northeast) winds and poorer humidity recoveries. -Wright && .PREV DISCUSSION... /Issued 449 PM PDT Sat Aug 21 2021/ Updated Aviation Discussion. DISCUSSION...Satellite imagery shows mainly clear skies across southern Oregon and northern California with a few cumulus here and there. Additionally, smoke remains intermittent across portions of Jackson County, the East Side, and northern California. Breezy winds from the west may help Jackson County clear out briefly this evening, but the other areas will remain smoky. This set of circumstances is consistent with a trough that is digging southeastward across the Pacific Northwest today and will exit the area tonight into tomorrow. This gave us our strong marine push early this morning, and expect another marine push tonight with marine stratus returning to the Coast and Umpqua Basin. There is a reasonable chance that the marine stratus could spill over into Jackson County once again tonight. Once this system leaves, the Pacific Northwest will remain in a zonal flow pattern with very weak troughs continually moving through through mid-week. This will create the potential for additional marine pushes across the west side, breezy winds and cooler temperatures for most of southern Oregon and northern California. Precipitation, however, is not expected within the forecast period except for light drizzle with the aforementioned marine pushes, largely closer to the coast--but it likely would not measure. Although this pattern continues for most of the week, models diverge their trend with the GFS ensemble trying to show more of a ridging pattern and the ECMWF ensemble showing more of a progressive "troughy" pattern. Although have largely based the forecast on the National Blend of Models, did not allow the full trend back to the thermal trough ridge with triple digit temperatures in west side valleys and mid 90s east of the Cascades. This is largely due to the fact that the NBM is leaning heavily on the GFS in this instance, and the GFS ensemble is not 100 percent on board with the strong ridge/thermal trough pattern. As such, it will be prudent to monitor these trends as another 100 degree day in Medford would have us break our record of the number of hundred degree days in a year. The current record is 23 days of 100 degrees or more, and it was set in 1990. For 2021 in Medford, we are currently sitting at 23 days of 100 degree plus days this year. -Schaaf && .MFR WATCHES/WARNINGS/ADVISORIES... OR... CA...None. Pacific Coastal Waters... - Small Craft Advisory until 5 PM PDT Monday for PZZ356-376. - Small Craft Advisory from 11 AM Sunday to 5 PM PDT Monday for PZZ350-370. $$ BTL/MAP/MNF
Area Forecast Discussion
National Weather Service Marquette MI
749 PM EDT Sat Aug 21 2021 .SHORT TERM...(This evening through Sunday) Issued at 242 PM EDT SAT AUG 21 2021 Water vapor imagery and RAP analysis show a vigorous, well-defined shortwave lifting ne into nw Ontario. Extending southward from the associated 992 mb sfc low is a pre-frontal sfc trough into central Upper Mi with the cold front lagging back into western Lake Superior and nw WI. Ahead of the trough, an area of stratocu is noted over central Upper Mi on visible satellite imagery. A broken/narrow line of convection (shra with some embedded isold thunder) is noted on radar from eastern Lake Superior into western Alger and eastern Delta counties where dewpoints are around 70F and MLCAPEs are noted in the 500-1000 j/kg range. As time goes on this afternoon, the better instability (MLCAPEs up to 1000 j/kg) will continue to get pushed into the eastern counties of the U.P. As a result, have generally confined convective PoPs the rest of the afternoon into the east half counties per latest 18Z HRRR run, which seems to have the best handle on the ongoing convection. Afternoon temps thus far under partly cloudy to cloudy skies have risen into the upper 70s to lower 80s. The vigorous shortwave over southern Manitoba will continue lifting ne, reaching Hudson Bay tonight. With best forcing/height falls shifting ne with it, forcing will be diminishing with the cold front moving across the fcst thru this evening. Expect breezy s winds gusting up to 25-30mph ahead of the cold front, strongest at Grand Marais in downsloping southerly flow. Postfrontal westerly winds will likely gust to around 40mph on the Keweenaw based on potential momentum transfer from mixing off fcst soundings. With incoming pres rises around 4mb/3hr providing an isallobaric wind component aligned with the gradient wind, would not be surprised if some gusts to around 45mph occur at times for a few hrs late afternoon/early evening. The southerly winds up Lake MI in advance of the cold front today will continue to build waves this afternoon so the high swim risk along the Lake MI beaches of Schoolcraft County still looks warranted into this evening. Shower potential will continue over the eastern fcst area this evening until the cold front exits. In the wake of the front, high pres will build toward the Upper Lakes tonight, bringing cooler and drier air into the area. Temps tonight should slip down into the upper 40s over the interior w trending up to around 60F along Lake Superior. Sunday, expect dry, cooler and less humid conditions as sfc high pressure builds in quickly from the west in the wake of the cold front. Max temps will probably be slightly cooler than seasonal normals with highs from the upper 60s/lower 70s north to the mid 70s interior west and south central. The cooler air in combination with dew points falling back into the upper 40s to mid 50s should make for a comfortable day. Waves generated from fairly gusty nw-n winds behind the front will likely warrant a high swim risk for Alger County and probably a moderate swim risk for Marquette County. .LONG TERM...(Sunday night through Saturday) Issued at 436 PM EDT SAT AUG 21 2021 This extended period looks to be somewhat active, with most of the chances for rain looking to happen near the later half of the period. To start off, we have a lifting low over northern MN that could bring some showers and thunderstorms over our far west. However, as the better forcing for the convection lifts upward and the front associated with it dies out over us, expect precip chances to be limited to the west Monday night. No severe weather is expected Sunday night as the instability should be too low. As height rises and WAA moves over us Monday, expect warmer temperatures, mainly in the west. A lot of the U.P. could see highs getting into the mid 80s Monday as a high pressure block remains over the southern US. Expect warmer temperatures again Tuesday as that same block remains pretty stationary and allows warmer temperatures from the Desert SW to advect over us. May see some showers Tuesday in the west as a low over the Canadian Prairie brings height falls over us. As this low traverses east through northern Ontario Tuesday and early Wednesday, expect shower and thunderstorms to move through Upper MI. Expect drier conditions Thursday as ridging begins to shift over us. Model guidance does hint at a pretty long-lived precip event early next weekend as troughing digs across the Northern Plains. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 737 PM EDT SAT AUG 21 2021 VFR conditions are anticipated to prevail through the period as a much drier airmass moves into Upper Michigan behind today`s fropa. The most significant impact continues to be the gusty winds, although KSAW has already begun dropping off, with indications pointing to KIWD on the decline as well. However, KCMX remains impressively gusty, still reporting 40 knots there. This shouldn`t last much longer, and have also indicated the downward trend there as the evening progresses. For Sunday, weather conditions are anticipated to be fair for aviation interests as surface high pressure regains control of the region through the remainder of this TAF period. && .MARINE...(For the 4 PM Lake Superior forecast issuance) Issued at 242 PM EDT SAT AUG 21 2021 A cold front will sweep across this afternoon and evening. After frontal passage, incoming pres rises from the w will give postfrontal west winds a boost. Until the axis of the pres rises passes, there will be the potential for some gale force gusts to around 35kt for a few hrs late aftn/early evening, particularly at higher obs platforms. The area from just w and n of the Keweenaw Peninsula toward Granite Island/Stannard Rock should be favored for the higher wind gusts. Winds will then diminish to under 20kt from w to e overnight thru Sun morning as high pres arrives. At the moment, it appears winds will remain generally under 20kt Mon thru Wed. && .MQT WATCHES/WARNINGS/ADVISORIES... Upper Michigan... Beach Hazards Statement until 10 PM EDT this evening for MIZ014. Lake Superior... None. Lake Michigan... None. && $$ SHORT TERM...Voss LONG TERM...TAP AVIATION...lg MARINE...Voss
Area Forecast Discussion
National Weather Service Pocatello ID
223 PM MDT Sat Aug 21 2021 .SHORT TERM...Tonight through Mon night. Showers and thunderstorms until late tonight with a frontal passage during the late evening. We are still in an area of a marginal threat for thunderstorms. Strongest thunderstorms if you believe the HRRR are tonight around 2100-2200 MDT in the Snake River plain, so an uneasy and unsettled night weather-wise. The front will continue its eastward trek Sun and poses a thunderstorm threat only over the ID-WY border. By Mon, skies will clear and the temperature will be up 5 to 10 degrees for afternoon highs after a seasonally cool overnight. Warming trend continues into the extended. With the upper level ridge returning, wind will calm down Sun but get breezy again Mon afternoon. Messick .LONG TERM...Tuesday through Saturday. Through the entire extended period Idaho is under a trof. Occasion short waves will move through the westerly flow, which will likely becmome more northwesterly as the week progresses. Timing of these short waves seems moot at this point, because they will be glancing blows to the north resulting in little to no threat of precipitation to Idaho through the period. Temperatures starting out relatively cool will finally push to normal levels by about Thursday. Deterministic GFS/ECMWF both show significant wave moving through next Saturday. While this still may be too far east to provide any wx, it should help keep temperatures from getting too warm. Crawford && .AVIATION... Scatteered light shower activity affecting various parts of the basin at this time, but some thunderstorms have already fired up over the favored southeastern Idaho area. Showers are featured as predominant wx at all TAFs this evening with the exception of SUN where they become less likely as system swings through from west to east tonight. Moisture will be deepest over the eastern highlands overnight, with some signifncant rains expected there. Thus have kept previous TAF depiction of MVFR cigs at DIJ after 05Z. Most areas will be clear and dry before 12Z with VFR outlook for Sunday. Only DIJ may still have some low level clouds to clear out first thing after sunrise before going SKC. Crawford && .FIRE WEATHER...Thunderstorms continue late tonight, some of them strong to severe in outflow wind with areas of heavy rain possible. Humid conditions will continue tonight and partially into Sun, but really dry air starts entering the Salmon-Challis NF and other Central Idaho Dispatch areas by then. This will spread to the southeast by Mon, with a few low elevations returning to below 15 percent. Mon is expected to see a return to gusty wind, so depending on fuels, there may be some critical fire weather conditions as early as that day. Lows continue to track through southern Canada during the upcoming week, not enough to bring any showers or thunderstorms except to perhaps the Targhee NF and northern end of the Idaho Falls BLM. The main benefit is that temperatures do not get really hot again until just beyond the upcoming 7 day period. The drawback is that these lows will bring breezy conditions while the landscape gets a chance to dry out. Messick .PIH WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 11 PM MDT this evening for IDZ422-425-427. && $$
For frequently asked questions about the Area Forecast Discussion
Area Forecast Discussion
National Weather Service Sacramento CA
158 PM PDT Sat Aug 21 2021 .SYNOPSIS... Smoke and haze from wildfires will continue to impact portions of interior Northern California. Below normal high temperatures will persist through early next week, warming to above normal Thursday into Friday. && .DISCUSSION... Water vapor satellite imagery depicts a trough tracking through the region this afternoon. This feature has resulted in increased onshore flow and cooler temperatures across interior NorCal. Forecast highs for this afternoon will range from the upper 70s to upper 80s in the Valley. However, thick wildfire smoke may inhibit warming at some locations. The HRRR smoke shows improvement across the Sacramento Valley as winds will continue to push smoke off to the east. GOES-West fire temperature product is showing intense heat signatures associated with the Caldor Fire this afternoon. Observed wind gusts have ranged in the 20-30 mph range across the higher elevations of the northern Sierra and southern Cascades. Local gusts up to 40 mph are still possible. These increased southwest winds will continue to bring elevated fire weather conditions to portions of interior NorCal. A Red Flag Warning remains in effect for portions of El Dorado County including the Caldor Fire until 8 PM PDT this evening given the potential for rapid spread of the existing fire. Lighter winds are expected tonight and Sunday as today`s trough ejects eastward. Ensembles and clusters favor troughing remaining along the West Coast early next week into mid-week. Temperatures will remain below normal through early next week with seasonal temperatures returning by mid-week. Locally gusty wind possible at times, mainly in the Delta and over higher terrain in the afternoons into evenings. && .EXTENDED DISCUSSION (Wednesday THROUGH Saturday)... Ensembles indicate that gradual warming and drying is likely to continue during the second half of next week as the weak trough gradually gives way to ridging from the eastern Pacific. Temperature will be close to average at mid-week, then warm to around 10 degrees above average by next weekend. Some increased north wind possible Thursday and Friday, which may bring smoke back to the valley. && .AVIATION... Smoke from area wildfires will continue to impact interior NorCal today. Local south to west surface wind gusts 15-30 kts in the Central Valley, strongest near the west Delta and mainly after 00Z. Widespread southwest surface wind gusts 15-30 kts Sierra Nevada through 02Z Sunday. && .STO WATCHES/WARNINGS/ADVISORIES... Red Flag Warning until 8 PM PDT this evening for Northern Sierra Including the Tahoe and ElDorado NF/S West of the Sierra Crest. && $$
...Update to aviation forecast discussion...

.DISCUSSION... Issued at 307 PM CDT Sat Aug 21 2021 20Z water vapor shows one shortwave trough lifting north of MN while another upper low propagates east over OR. Ridging was noted along the gulf coast. This placed the forecast area in a weak west southwesterly flow aloft with no obvious forcing upstream. At the surface, a cold front had pushed into the TX panhandle and the Ozarks. Drier air had moved through the northern parts of the forecast area and the north breeze has been somewhat refreshing. The pattern over the next several days keeps the upper ridge over the southern plains while the mean westerlies impact the northern tier of the country. So forcing for precip does not look overwhelming from the model progs. However there may be some isolated showers and thunderstorms over the coming 24 to 36 hours. The first opportunity looks to be Sunday morning. There is reasonable agreement from the operational solutions for a return flow to develop late tonight and the RAP and NAM have some decent theta-e advection along with good isentropic upglide. Forecast soundings suggests there could be some elevated CAPE on the order of 1000 J/kg. While QPF progs are not overwhelming, there is some signal for isolated showers and storms developing around daybreak across central KS. So have inserted a slight chance POP through mid morning to cover this potential. The second opportunity should be Sunday evening. Models continue to show storms developing across central NEB within an axis of low level moisture convergence. The general flow may allow for some of these storms to skirt the state line and move into some of the northern counties. The NAM and GFS show plenty of instability developing as low level dewpoints in the 70s surge back north through the day and 0-6KM bulk shear may be a little better for organized updrafts. So we`ll need to be on the lookout for some severe weather affecting parts of northern KS Sunday evening. With the dry air moving south tonight and skies mainly clear, think lows will fall into the lower and middle 60s. A southerly wind develops early Sunday with the warm air and moisture returning north through the day Sunday. With this highs are expected to be back into the upper 80s and lower 90s. We could even see some heat indices around 100 across central KS is the dewpoint forecast is correct. The forecast for Monday through Wednesday is for hot and dry weather to return. The overall pattern changes little with the center of the upper ridge drifting north over OK. So prospects for decent forcing look low and flow is likely to be pretty weak. because of this POPs were kept at 10 percent or less. Will need to watch out for heat indices in the afternoons as forecast highs are expected to climb back into the middle 90s to around 100. Lows look to be mild with middle 70s forecast. Thursday through Saturday does not see a significant change to the pattern. the National Blend of Models (NBM) has some 20 to 30 percent POPs in the forecast with the potential for a weak boundary to slide into northern KS. However the 12Z operational runs look to stall the boundary out near the NEB state line. Confidence in POPs is marginal and have not changed what the NBM has inserted since it basically is close to climatology. With the 12Z models keeping the boundary north of the area Thursday, trended temps warmer with highs remaining in the middle to upper 90s for Thursday. Looking just beyond the forecast, the ECMWF and GFS have a shortwave trough digging into the central plains with a cold front moving in. Timing differences add some uncertainty, but think the better potential for widespread rain may be Saturday night or Sunday of next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) Issued at 542 PM CDT Sat Aug 21 2021 VFR conditions continue through the overnight with dry air in place. Moisture return takes place into the morning tomorrow with cumulus developing as mixing takes place with some stronger winds mixing to the surface making for generally breezy conditions from the south. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...Wolters AVIATION...Drake