Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/23/22

Area Forecast Discussion
National Weather Service Charleston SC
1026 PM EST Tue Feb 22 2022 .SYNOPSIS... Atlantic high pressure will prevail through late week, before a cold front passes through Friday night. The cold front could stall offshore through the weekend. High pressure will return early next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... IR satellite images late this evening indicated clear conditions across the forecast area. Given the clear sky and light winds, temperatures are on pace to fall into the upper 50s by daybreak Wednesday. The primary forecast challenge will be with the placement and timing of potential sea fog tonight. Latest runs of the HRRR is consistent with earlier runs, showing sea fog developing over the nearshore GA waters after midnight. SREF probabilities of vis <=3 miles increase across the SC/GA nearshore waters during the pre-dawn hours. Based on the model trends, I will increase the mention of fog to indicate areas of fog within 20 nm off the GA and lower SC coast late tonight. Fog will struggle to develop over land given light and steady sfc winds. However, it is possible that rounds of sea fog may spread across the coastal areas. The fog could become more widespread and the need for Dense Fog Advisories can`t be ruled out. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... Atlantic high pressure will continue to extend into the area on Wednesday, although a weak cold front will approach late in the day. The front could stall near or just north of the area before lifting back north later in the period. A weakening shortwave will bring the next cold front towards the area on Friday. Lack of significant forcing will maintain a dry forecast throughout. Perhaps the most notable aspect of the forecast is the stretch of unseasonably warm temperatures. Most locations away from the cooler coastline will peak in the 80-85 degree range each day. Overnight temperatures will also be quite mild with lows generally in the upper 50s to around 60. In addition, reduced visibilities in fog will be possible each night into early morning, especially closer the coast where sea fog could move onshore. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... A cold front will push through the area Friday night and likely stall offshore and to the south through much of the weekend. An upper disturbance will move through the region on Sunday which could support isolated to scattered showers. Dry high pressure is then expected to return for early next week. Temperatures will gradually cool through the period. && .AVIATION /03Z WEDNESDAY THROUGH SUNDAY/... Prior to the 0Z TAFs, satellite, obs, and webcam at KJZI showed some stratocu with MVFR bases near the terminal. Based on satellite trends, these clouds should drift away from JZI early this evening. KCHS and KSAV are forecast to remain VFR through this evening into the late night hours. During the pre-dawn hours into the early daylight hours Wednesday morning, forecast soundings indicate that an inversion will develop between 1.5-2 kft. Moisture below the inversion could create a period of restrictive ceilings, highlighted in the TAFs with a TEMPO from 10-14Z. High resolution guidance indicates that sea fog will likely expand late tonight into Wednesday night, expected to generally remain over the waters. Conditions should become completely VFR after 14Z with steady SW winds. Extended Aviation Outlook: Flight restrictions possible in fog/low clouds each night and early morning through late week. && .MARINE... Tonight: Southerly flow will prevail across the local waters with wind speeds generally topping out around 10 knots. Seas should average 2-4 feet, highest in the outer GA waters. The main forecast challenge will be the potential for sea fog to develop. Current model guidance favors fog developing as early as the early morning hours along the GA coast and then spreading north through sunrise and thereafter. There is still quite a bit of uncertainty regarding the timing, coverage, and intensity of the fog so the forecast only mentions patchy fog for now. Dense Fog Advisories could be needed late tonight and we will continue to highlight this in the Hazardous Weather Outlook. Wednesday through Sunday: South to southwest winds will prevail through late week. Speeds will average 15 knots or less, although the Charleston county waters could peak in the 15-20 kt range Friday afternoon ahead of a cold front. Seas will be 2-5 feet. The front will cross the area Friday night and winds will flip around to the northeast for at least the first half of the weekend. At this point, conditions look to stay below Small Craft Advisory criteria. Sea Fog: Conditions will remain favorable for sea fog through Friday. Fog could become dense at times, and Dense Fog Advisories could be needed. This potential remains highlighted in the Hazardous Weather Outlook. && .CLIMATE... STATION RECORD HIGH TEMPERATURE --------------------------------------------- RECORDS FOR 02-23 KCHS 82 2018 KSAV 84 2012 KCXM 78 1980 --------------------------------------------- RECORDS FOR 02-24 KCHS 83 2018 KSAV 86 2012 KCXM 81 1930 --------------------------------------------- RECORDS FOR 02-25 KCHS 86 2018 KSAV 87 2018 KCXM 80 1930 && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...NED SHORT TERM...ETM LONG TERM...ETM AVIATION...NED MARINE...BSH/ETM CLIMATE...
Area Forecast Discussion
National Weather Service Gray ME
731 PM EST Tue Feb 22 2022 .SYNOPSIS... Warm moisture rich air will filter into the region tonight with rain and anomalously warm temperatures for Wednesday. Canadian high pressure will build in for Thursday with accompanied by a notable drop in temperatures. Attention then turns to a winter storm system coming out of the Ohio Valley which will have potential for widespread accumulating snowfall Friday. More seasonable temperatures and weather expected for this weekend. && .NEAR TERM /THROUGH TONIGHT/... 730 PM UPDATE... Surface temperatures continue to be the primary point of consternation at this time WRT ongoing freezing rain event over the interior. The CAD is making its presence well known today with a northeasterly to northerly wind over the interior feeding in lower dew points... and allowing precipitation processes to keep temperatures well below freezing in some portions of the western Maine mountains/lakes region, but also bring temperatures back below freezing in other areas along the southern and eastern periphery of the afternoon`s Winter Weather Advisory. Thus have expanded the Advisory into interior York and Sagadahoc, where onshore flow will take longer to work in warmer temperatures. Road temperatures aren`t particularly favorable in these marginal areas however elevated surfaces still stand a good chance of ice accretion. Latest hires guidance (mainly the HRRR grasps onto the CAD sufficiently) still indicates this threat will wane over the entire region by the 06Z target end time of the product... but will closely monitor surface T trends in case an extension is needed. PREVIOUSLY... Icy night for some, rain for most tonight. Winds become gusty tonight, shifting for Wednesday as low pressure pulls into the Canadian Maritimes. Winter Wx: Temperatures across the region have warmed well since a cool push of air last night. This has resulted in max temps in the upper 30s to around 40 for much of southern and central NH as well as coastal ME. With these above freezing temps invading southern portions of the Winter Weather Adv, have chosen to cancel it for interior York Co ME and Belknap/Grafton Counties in NH. Do want to mention that some locations in these counties could have been sheltered from the warmer air, thus a few slick spots could develop on the front end of precip onset this afternoon. Temperatures across the interior, sheltered by terrain, are still well below freezing, with NAM, ECMWF, and GFS Tw aloft indicating a quick invasion of warm air. This sets up a fairly good environment for freezing rain this afternoon and evening for the remaining WWY area. Have increased amts the most across Somerset Co where up to a third of an inch of ice may be possible at the extreme. Limiting factors may be precip rate, and advancing warm air. Rainfall rates, focused between 7pm and midnight, may be such that it does not have time to freeze and cling before washing away on surfaces. Warm air mixing from aloft as well as advancing from the south at the sfc should overcome the remaining temps in the 20s after midnight, tapering to rain showers. Wind: Light NNE winds will increase rapidly from the S this evening and overnight. This will be felt the most in the mtns and along the Penobscot Bay region. Issued a Wind Adv for this area for southerly gust potential up to 50 mph late tonight. While an inversion should keep these stronger winds at bay for much of the coast, this protection weakens along the Midcoast. This with the mod to potentially brief heavy rain rates tonight could mix these LLJ winds down. && .SHORT TERM /WEDNESDAY THROUGH WEDNESDAY NIGHT/... A broad warm sector envelops the CWA Wednesday morning, with temperatures soaring near rec highs. 60s move into southern NH and up coastal ME. It will also be quite breezy Wednesday as mid to low level winds dip in heights and sfc mixing reaches up to about 900mb. While showers will have tapered through the morning hours, any additional clearing could enhance how much of these winds carry to the sfc. This would be more widespread wind gusts than Tues night, up to 30mph or more possible. With the bulk of the day dry and windy, believe most surfaces should dry out ahead of crashing temperatures Wed night. Winds shift NW, with CAA wiping across the CWA. Lows fall into the mid teens for a bulk of the region, with lows around 20 for southern NH. The large temp swing combined with precipitation will have some hydro impacts, or the potential, see Hydrology section. && .LONG TERM /THURSDAY THROUGH TUESDAY/... Confluent flow over New England will keep subsidence and associated high pressure with quiet weather on Thursday. The main forecast challenge will be with the track and subsequent snowfall amounts with a winter storm Thursday night through Friday night. Once again we will see an impressive warm conveyor with deep moisture with a potent 25H jet enhancing lift from the the Ohio Valley. The system will fill/weaken somewhat before giving way to a new area of surface pressure/cyclogensis off the southern New England coast late Friday. Some differences with the upper and surface patterns with this system, but overall looking at the H850 jet seems to keep the system centered mainly south of the forecast area, with the GFS the northernmost/wettest model. The anomalous moisture combined with some modest QG forcing from the strong upper level jet streak should yield widespread qpf from 0.5-1" in southern half of the CWA, somewhat lesser amounts north. Snow growth region is cold so looking at large flakes and higher snow ratios, especially in interior Maine/N NH. The weaker lift along the international border will result in less QPF amounts, but the snow ratios will be a big factor in overall totals. Overall models favor plowable snowfall for much of the area, highest in southern Maine and New Hampshire. Given the timing of the system expect a difficult morning and evening commutes. The storm will be followed by cool and dry high pressure for the weekend. A weak front on Sunday will bring some light snow showers, primarily in interior mountain regions. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... Short Term...IFR to LIFR possible tonight, improving to VFR Wed morning. LLWS also likely at most TAF sites, greatest along the NH/ME coast. Rain lifts through the area tonight, with fog possible, especially where there is snow cover for interior sites. Gusty winds S winds tonight, shifting W Wednesday, and then NW Wednesday night. Long Term...High pressure will favor fair conditions with VFR Thursday. Widespread restrictions and wintry mix developing late Thursday night and continuing into Friday. && .MARINE... Short Term...Southerly Gale conditions tonight, slackening and shifting W Wednesday with SCA conditions continuing. Wave heights increase 6 to 12 ft tonight, and become 4 to 8 ft Wed afternoon. SCA conditions diminish towards Thurs morning. Long Term...Looking at small craft conditions on Friday with the low pressure system just south of the forecast area. This system will support waves Strong NE/N winds 20-25 kts, and then NW Saturday behind the cold front. Seas will at least briefly reach 6+ ft over the outer central waters during the event. && .HYDROLOGY... Flood watch posted for the NW as rain increases in coverage across the area later today/tonight, and QPF and snow melt could combine to make some minor flooding. Recent warm ups have helped rot some river ice, so there is a risk for ice jam flooding primarily in smaller rivers and tributaries. The main stem rivers have ice 9" or thicker, which should limit break up potential given only modest river rises. Looking at impressive high temperatures on Wednesday which will continue the melting/runoff well into Wednesday night. This will keep a threat for ice jam related flooding ongoing even once the rain ends. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...Flood Watch from 1 AM EST Wednesday through Thursday morning for MEZ007-012. Winter Weather Advisory until 1 AM EST Wednesday for MEZ007>009-012>014-018>021-025-033. Wind Advisory until 6 AM EST Wednesday for MEZ027-028. NH...Flood Watch from 1 AM EST Wednesday through Thursday morning for NHZ001>007. Winter Weather Advisory until 1 AM EST Wednesday for NHZ001- 002-004-006. MARINE...Gale Warning until 7 AM EST Wednesday for ANZ150>154. && $$ UPDATE...Casey NEAR/SHORT TERM...Cornwell LONG TERM...Jamison HYDROLOGY...Jamison
Area Forecast Discussion
National Weather Service New Orleans LA
829 PM CST Tue Feb 22 2022 ...EVENING UPDATE... Primary focus for this evening will be for ongoing fog production across coastal marine areas and how far this will spread/build down inland through the overnight hours and into the morning on Wednesday. Looking over the latest 01Z NBM <1mi VIS probabilities hits the greatest chances over just about all of coastal MS, where obs are already slowly coming down right along the coast. GOES-16 Night Fog [11.2-3.9um] shows the thickest low clouds starting out from Hancock east to Jackson, with a slight haze of light fog for all surrounding nearshore marine zones. With light southerly winds tonight and slightly higher observed dewpoints over SSTs in the upper 50`s to low to mid 60`s, conditions will be much better for fog production and maintenance. Looking like fog will become more dense for nearshore coastal waters earlier on later tonight, then spreading inland. Only lower confidence location of the current Dense Fog Advisory is upwards into the Atchafalaya Basin just how far north fog can form, spread and maintain, but feeling good about the current area for now. Otherwise, it will be primarily dry tonight. Latest 00Z HRRR hints at some light isolated showers/drizzle east of I-55 including the MS coast, but not entirely seeing support other than subtle 295 to 300k isentropic ascent at work, and perhaps some localized sfc convergence. Additionally, we`ll see the cold front from our northwest approach NW parts of the CWA early in the morning. For winds, loaded in the NBM with a stronger bias towards the HRRR to account for a realistic frontal position and attendant wind shift, likely getting into MCB around early to mid-morning. Something to note, where the front ends up (likely somewhere near BTR to Franklinton line) will determine how far post-frontal CAA can build in, which could keep temperatures a lot cooler in this area today underneath thicker cloud cover. On the other side of the front in the warm sector, short-range guidance hints at skies eventually clearing out to mainly partly cloudy slowly into the late morning and afternoon. This may lead to a slow diurnal curve/warm up in temperatures in the morning, but may still warm up fast in the afternoon if sunshine can become more widespread. Played it with a blend of the 50th/75th percentile areawide south of the front, but nudged a cooler 25th/50th percentile blend for northwestern areas. Additionally, just enough sfc frontogenetics combined with building instability in the PBL to 800mb layer (below the same subsidence inversion locked in place) may likely get some scattered showers going, with better chances closer to the frontal boundary mid/late morning through all afternoon. NBM hourly PoPs reflect this well as short-range guidance is in good agreement over this idea. Later in the evening and into tonight, the front will remain stationary but slowly start to retreat back north. Should the front remain locked up longer than anticipated, continued frontogenetic ascent in the low-levels may maintain scattered showers for northern areas even into the early overnight hours before midnight. KLG && .AVIATION (00Z TAF DISCUSSION)... Few patchy low clouds this evening will persist for the next few hours with primarily VFR to a few areas of MVFR. By 03 to 06Z, marine fog will likely begin to build inland across coastal areas reaching coastal TAF sites first, with IFR or lower flight categories expected to begin in this time frame (intermittent CIGS in the VV003 to VV002 range). More fog will likely build in north to around the I-10/12 corridor from BTR to HDC/ASD corridor beyond 06Z into daybreak. Given the atmospheric conditions expected, areas of dense fog may persist beyond daybreak for coastal TAF sites with impacts expected to continue, with some slow improvement possible late morning to around noon. Otherwise, light showers on radar this evening will continue to dissipate, with another round of scattered light showers at times mainly during the afternoon on Thursday with no additional impacts expected. KLG .PREV DISCUSSION... /issued 420 PM CST Tue Feb 22 2022/ SHORT TERM...As we watched radar and satellite today it looked much like a late spring or even summer day with scattered to numerous popcorn like showers developing. Rather decent cloud cover and even sprinkles earlier kept the area from warming fast this morning along with keeping the afternoon highs from quite reaching the values initially expected. The next 3 days will be difficult from a forecast standpoint because that will have a lot to do with the location of a cold front that is expected to enter the CWA during the early morning hours. What are the concerns about this? First and the greatest impact is fog tonight and probably again tomorrow night. Second is temperatures, there will be a rather decent temperature gradient depending what side of the front you are on. Temperatures will also be impacted by rain much like it has been today. So first fog concerns. Like the previous forecaster mentioned very rich moisture with dewpoints in the 70s has moved over much cooler shelf waters. The difference is as much as 10-15 degrees (maybe even 20 in isolated areas) and as soon as the sun goes down there is a good chance of fog developing over the coastal waters right around the coast but what about the land areas? Initially it looks like LL winds would be too strong leading to more of a thick stratus deck developing but winds are expected to slowly decrease overnight. As this happens there is a good chance that the stratus deck will slowly drop towards the sfc and for areas south of the I 10/12 corridor and especially coastal MS and coastal SELA fog could begin to develop as early as late this evening. Coastal zones have the greatest threat as marine fog could also advect in with a weak southerly wind along the coast. Looking at forecast soundings near GPT and MSY it appears that the stratus deck expected could drop quickly in these areas with dense fog impacting these locations before midnight. One last positive for fog is we have a weak cold front trying to slide down into the region before sunrise and generally these slow moving cold front will have moisture pool ahead of it this will also aid in the production of fog tonight. Again the biggest concern over the land areas is stratus not dropping to the sfc due to strong LL winds however, the threat of moderate to dense fog is pretty good. With that we have issued a dense fog for a good chunk of the region tonight. We just mentioned the cold front approaching and that will be a problem through the short term forecast. The ridge over the southwestern Gulf will remain strong with deep west-southwest flow aloft and this will provide no real push to get the front through and it will likely stall over the area early tomorrow. This will help provide a little bit of a focus to get scattered showers across portions of the CWA tomorrow. As a sfc low starts to take shape near the TX/OK panhandle it will likely cause the stalled front to lift back to the north as a warm front. That will be short lived though as a sfc low develop over southern TX will lift northeast with a s/w moving through the plains and into the Mid MS Valley. This low will track into KY and WV and it will finally drive a cold front into the Gulf but it will be slow. Additional light rain is possible with this front. LONG TERM...Quite a bit of uncertainty in the extended portion of the forecast. Ensemble means are in good agreement with the pattern setup this weekend and early next week but b/c of this there could be rather large shifts with respect to temperatures and frontal locations. Confidence is rather low in the forecast so we will stick to the NBM at this point but an honest opinion it along with most of the guidance appear to be a little on the high side respect to morning lows a few days. This weekend and into next week it is all about the cold front. Model spreads in the temperatures, especially the NBM is rather large. That said all of the deterministic guidance is on the lower end and most of the ensemble guidance is on the lower end as well. Honestly with the setup though we would like to lean a little higher with the temps but given everything is lower we have a hard time finding the confidence to make that change right now. This starts as early as Saturday morning with forecast lows in the mid 40s to mid 50s but given the slow push of the front and the likelihood of overrunning moisture bringing clouds and even possibly rain, morning lows should really struggle to get that low. If the cold front has a cleaner push then the morning low forecast is fine. There is another re-enforcing cold Sunday and that should finally drive through completely with northwest flow finally in place Sunday night this will likely provide cool yet nice conditions across the region for Lundi and Mardi Gras. /CAB/ MARINE...Biggest concern for the marine areas will be fog. Very rich moisture with dewpoints about 10-15 degrees or even more warmer than the SST should easily allow for the production of Marine fog quickly this evening. Winds will relax as well overnight but could help to advect some of the fog inland. Cold front will stall north of the coastal waters tomorrow but a cold front should finally drop into the Gulf Saturday and a strong one on Sunday. /CAB/ && .PRELIMINARY POINT TEMPS/POPS... MCB 65 81 62 81 / 40 40 20 30 BTR 66 83 63 82 / 10 40 20 30 ASD 65 81 60 79 / 10 20 10 20 MSY 67 81 65 79 / 10 20 20 20 GPT 63 76 60 74 / 10 10 10 10 PQL 64 79 60 74 / 10 10 0 10 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...Dense Fog Advisory until 10 AM CST Wednesday for LAZ046>050- 056>061-063>070-072-075>078. GM...Dense Fog Advisory until 10 AM CST Wednesday for GMZ530-532-534- 536-538-550-552-555-557. MS...Dense Fog Advisory until 10 AM CST Wednesday for MSZ080>082. GM...Dense Fog Advisory until 10 AM CST Wednesday for GMZ532-534-536- 538-550-552-555-557. && $$
National Weather Service Morristown TN
926 PM EST Tue Feb 22 2022 .UPDATE... EVENING UPDATE. && .DISCUSSION... The front is still off to our west, but showers and some thunder are moving northeast with the flow across our area and the overall motion of this band of precip has slowed to a crawl allowing training which is bringing heavy rainfall especially southern and western areas. The Flood Watch still looks to be warranted given this set up. The shear is strong, but limited instability has led to convective cells weakening as they move into our area. This trend should continue, but we will still need to be alert for any stronger storm and brief tornado spin ups mainly Southern Plateau and adjacent areas. Will lower most temps a bit with this update given many obs are approaching lows already. Will also bump winds up a bit over the higher elevations. && .AVIATION... 00Z TAF DISCUSSION. Will see rain and perhaps some rumbles of thunder especially CHA moving across the area tonight. Conditions will become mainly MVFR/IFR as the precipitation moves through, with some improvement during the day Wed although MVFR cigs look likely to linger for much of the day. LLWS looks borderline early tonight but the best chance looks to be at CHA, so will include it for a few hours there. && .PREV DISCUSSION... /ISSUED 311 PM EST Tue Feb 22 2022/ SHORT TERM...(Tonight and Wednesday)... Key Messages: 1. Focus of heavy rainfall tonight along a mesoscale boundary for the central East Tennessee valley and northern Cumberland Plateau. One to three inches expected with locally higher amounts. 2. Drier Wednesday with clouds hanging around for most areas. Discussion: Current radar imagery shows a line of rain extending from SW VA across the northern Cumberland Plateau and southwestward through Middle TN. This will provide an mesoscale focus for additional rainfall through the evening and overnight hours. Ahead of the cold front tonight, southwest winds increase with the RAP showing a focus of low-level boundary layer convergence across the I-40 corridor through Middle TN and into East TN. The strongest low- level convergence will likely be later tonight between 05z and 09z across the northern Cumberland Plateau and central East Tennessee Valley near Knoxville. The RAP shows PW values around 1.5 to 1.6 inch during this time period with low values of skinny MUCAPE around 200 J/Kg. This will be supportive of heavy rainfall rates and potential training as convection develops with storm layer steering flow nearly parallel to this mesoscale boundary. HREF guidance continues to indicate the potential for 1 to 3 inches of rain with locally higher amounts, and with morning rainfall today, 6-hr FFG are now around 2 to 2.5 inches or less because of the wetter antecedent conditions. With the anomalously high moisture and being in the warm sector, temperatures remain well above normal tonight. The cold front should be mostly southeast of the area by 15z Wednesday with slightly drier air arriving behind the front. Expect to continue with mostly cloud sky conditions, especially across the valley and eastward around the mountains and foothills. Max temperatures remain slightly above normal with upper ridging and the bulk of cold air remaining to our northwest as the cold front stalls out just to our south. JB LONG TERM...(Wednesday night through Monday night)... Key Messages: 1. Another system will impact the region Wednesday night through Friday morning with locations north of I-40/I-81 expected to see heavier totals of an additional 1" to 2" or more of rainfall. 2. Saturday is dry and cooler before another system is expected Saturday night through Sunday. Confidence remains limited, but an area-wide rain/snow mix is possible. Snow accumulation (if any) will likely be confined to the higher elevations of the Northern Cumberland Plateau, SW Virginia and the East Tennessee Mountains. Wednesday Night through Friday In the upper levels, a ridge will be over the Southeast with nearly zonal flow over the region becoming more southwesterly Thursday night. At the surface, a boundary will develop near the Tennessee/Kentucky state line on Wednesday night. This boundary will slowly lift north on Thursday. Thursday night this system will get better organized with a more discernible low and cold front. The cold front will move through the region late Thursday night into Friday morning. The first round of rain will be along the stationary/warm front Wednesday night and Thursday. A steadier rain and therefore higher rain totals are expected along and north of I- 40/I-81 with 1 to 2 inches total forecast there in addition to rain received earlier this week. The second round of rain will be more widespread as the cold front moves through late Thursday night into Friday morning. Minor flooding issues may occur late this workweek mainly north of I-40/I-81. Ponding of water on roadways and ponding in low lying areas are the biggest concerns. Conditions do not look favorable for strong or severe storms since instability will be low. A few rumbles of thunder cannot be ruled out. Saturday will be dry and cooler with highs in the upper 40s and near 50. The next system is expected Saturday night into Sunday. Temperatures will be cool enough Saturday night to get a rain/snow mix in many locations. Confidence remains limited, but this does not look like a big event at this time. Snow accumulation (if any) will likely be confined to the higher elevations of the Northern Cumberland Plateau, SW Virginia and the East Tennessee Mountains. Monday and Monday night will be dry and cool with highs in the upper 40s and lower 50s. McD && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 56 66 50 72 52 / 90 60 40 30 60 Knoxville McGhee Tyson Airport, TN 54 62 47 67 52 / 100 60 60 60 50 Oak Ridge, TN 54 61 45 64 50 / 100 50 60 60 60 Tri Cities Airport, TN 52 61 45 61 50 / 100 60 60 80 40 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...Flood Watch until 7 AM EST /6 AM CST/ Wednesday for Anderson- Bledsoe-Blount Smoky Mountains-Bradley-Campbell-Claiborne- East Polk-Grainger-Hamilton-Hancock-Knox-Loudon-Marion- McMinn-Meigs-Morgan-Northwest Blount-Northwest Monroe-Rhea- Roane-Scott TN-Sequatchie-Southeast Monroe-Union-West Polk. VA...Flood Watch until 7 AM EST Wednesday for Lee-Wise. && $$
Area Forecast Discussion
National Weather Service San Diego CA
113 PM PST Tue Feb 22 2022 .SYNOPSIS... A cold winter storm has arrived in SoCal, which will continue to bring rain and snow showers, gusty west winds, and cold temperatures through the middle of the week. Just as quickly as the trough will dig south through tomorrow, high pressure over the Pacific will expand as the storm departs to the east. Though dry weather can be expected starting Thursday, Thursday and Friday mornings will be quite cold for areas west of the mountains especially. A warming trend will begin Thursday as well, where temperatures are expected to reach near average by the weekend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... .SHORT TERM...(Today through Wednesday Night)... A large trough will continue to dig south into Southern California today and Wednesday. This has led to the chilly temperatures we are seeing this afternoon with many areas currently with widespread 50s for the coastal valleys and 30s/40s for our mountain areas. Gusty winds have accompanied this system where gusts over 50 MPH will continue across parts of the mountains and deserts through tonight. Coastal and valley regions west of the mountains will continue to see west winds gusting near 35 MPH at times. Hi-res model guidance points to less wind by Wednesday but still gusty across mountains and desert regions with widespread gusts 30-40+ MPH possible. Scattered showers this afternoon will increase in coverage as the trough moves south and east over SoCal this evening. Heaviest precipitation will be expected area wide tonight into early Wednesday morning, diminishing from north to south on Wednesday. Rain totals will be greatest over San Diego County per latest WPC, local WRF, and HRRR guidance. Most areas west of the mountains in SD County will see one half to locally over one inch of rain, which OC/IE will receive near one quarter. Deserts may also see a bit of rain as well! Orographic lift will be most prominent across RIV and SD Counties favoring high precip totals, including snow. These areas will see widespread snow totals of 8-12 inches in higher terrain, locally one to two feet in some spots. && .LONG TERM...(Thursday through Early Next Week)... High pressure will build off the Pacific on Thursday and expand into California slowly into the weekend. Though we will see a gradual warming trend, low temperatures will be quite cold on Thursday and Friday mornings, especially in valleys west of the mountains. ECMWF Extreme Forecast Index along with NBM 10th percentile and GFS MOS point to single digits widespread mid 20s to low 30s for the valleys of SD County into the Inland Empire by Thursday morning, which may lead to freeze conditions. Friday morning will be slightly warmer, but we still may see ares dip below the freezing mark. As the high moves over the southwest, this will lead to more dry weather by Thursday into the weekend. High temperatures will return to average readings by this weekend. A weak shortwave may brush the region by early next week, which would provide cooler temperatures and greater onshore flow. && .AVIATION... 222045Z...BKN-OVC030-040 with tops to 15000 feet with SHRA through 24Z, lowering to BKN-OVC020-030 from 00Z-14Z with widespread SHRA/TSRA over/west of the mountains. -SHRA extending into deserts. CIGS 2000 feet and vis 1-3 SM in heaviest showers. Mountains: Obscured in clouds/fog/pcpn. Mountains experiencing near blizzard conditions at times from 00Z-14Z with 30-50 kt winds and heavy snow. Snow level lowering to 2000 feet overnight. Deserts: West to northwest winds through the passes and down the desert mountain slopes with gusts 30-50 kt. Strong up/downdrafts over/east of the mountains with rotors and LLWS vcnty KPSP. Reduced visibility to 1-4 miles in BLDU at times. && .MARINE... SMALL CRAFT ADVISORY THROUGH 10 PM WEDNESDAY for northwest winds of 15-30 kt and steep choppy seas from a large short-period swell. Scattered showers and thunderstorms through Wednesday morning. No marine hazards are expected Wednesday night through Saturday. && .BEACHES... Elevated surf of 3-6 feet from a short-period northwest wind swell today through Wednesday. High rip current risk. Ocean water temperatures from 57-61 degrees. && .HYDROLOGY... Mostly light showers will continue this afternoon with the greatest coverage along and near the coastal slopes of the mountains with widespread showers in the mountains. Widespread showers will develop near sunset over the region. Some showers could produce small hail or graupel. There is also a slight chance of thunderstorms for late this afternoon into early Wednesday morning. Snow levels around 4500 feet this afternoon will fall to 2000 to 2500 feet for late tonight into Wednesday morning. Showers will continue on Wednesday with greatest coverage in the mountains and across San Diego County. Showers will end from the northwest late Wednesday afternoon and Wednesday night. For Orange and southwestern San Bernardino Counties through Wednesday, rainfall and liquid equivalent above the snow level is expected to range from one-tenth to one-quarter inch near the coast to one-half to one inch in the mountains with locally greater amounts with mostly one-tenth inch or less in the high desert. Light snowfall is possible down to around 2000 feet with 4 to 6 inches from 4000 to 6000 feet and 6 to 12 inches above 6000 feet with locally greater amounts on higher peaks. For San Diego and western Riverside Counties through Wednesday, rainfall and liquid equivalent above the snow level is expected to range from around one-half inch near the coast to 1 to 2 inches in the mountains with mostly one-tenth to locally one-quarter inch in the lower deserts. A snow level around 4500 feet will lower to around 2500 feet for late tonight into Wednesday morning. Light snowfall is possible down to around 2500 feet with 6 to 12 inches above 4000 feet with local amounts of one to two feet on the higher peaks. && .SKYWARN... Skywarn activation is requested. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...High Wind Warning until 4 PM PST this afternoon for Riverside County Mountains-San Diego County Mountains. Winter Storm Warning from 4 PM this afternoon to 6 PM PST Wednesday for Riverside County Mountains-San Diego County Mountains. High Wind Warning until 9 PM PST this evening for Coachella Valley-San Diego County Deserts-San Gorgonio Pass Near Banning. Winter Weather Advisory from 4 PM this afternoon to 6 AM PST Wednesday for Apple and Lucerne Valleys. Wind Advisory until 4 PM PST this afternoon for Apple and Lucerne Valleys-San Bernardino County Mountains. Freeze Watch from Wednesday evening through Thursday morning for San Diego County Valleys. Wind Advisory until midnight PST tonight for San Diego County Coastal Areas-San Diego County Valleys. Winter Storm Warning from 4 PM this afternoon to noon PST Wednesday for San Bernardino County Mountains. Winter Weather Advisory from 4 PM this afternoon to noon PST Wednesday for Santa Ana Mountains and Foothills. Hard Freeze Watch from Wednesday evening through Thursday morning for San Bernardino and Riverside County Valleys-The Inland Empire. Wind Advisory until 6 PM PST this evening for Orange County Coastal Areas-Orange County Inland Areas-San Bernardino and Riverside County Valleys-The Inland Empire. PZ...Small Craft Advisory until 10 PM PST Wednesday for Coastal Waters from San Mateo Point to the Mexican Border and out to 30 nm-Waters from San Mateo point to the Mexican Border Extending 30 to 60 nm out including San Clemente Island. && $$ PUBLIC...APR AVIATION/MARINE/BEACHES...Moede
Full Forecast Discussion:

Temperatures have struggled to warm even a few degrees today due to continued cold air advection behind yesterday`s strong front. The tight pressure gradient currently evident on surface maps is keeping winds breezy across KS as low pressure exists east of the area and a 1045 mb surface high resides in Montana. The combination of very cold ambient temperatures and continued breezy north winds tonight will create dangerous wind chill readings tonight and Wednesday morning. Thus, we have issued a Wind Chill Advisory from 8 PM this evening until 11 AM Wednesday where wind chills are expected to drop to -15F or lower. After sunrise, temperatures should increase more than they did today, however, we went with the 25th percentile of model guidance for afternoon highs, which would keep temps generally in the low 20s. The next storm system to watch is a mid-level system set to move out of the Four Corners region on Thursday. A cold air mass will remain in place so if precipitation occurs, it will be of the wintry variety, largely in the form of snow. Deterministic models are still not in great agreement with the amount of saturation through the DGZ on Thursday, and the amount of ascent that will occur as the system advances toward the area. SREF plumes show decent agreement in lower snow totals with an average between 0.5" and 1.0" of snow in Topeka. GEFS plumes average a little higher, around 2.0" of snow in Topeka. Until confidence increases, we are going with a uniform 0.5" to 1.0" of snow accumulation area-wide on Thursday. South of I-35, freezing drizzle also looks possible for a few hours where conditions look drier in the DGZ. Following some light snow or freezing drizzle on Thursday, temperatures will undergo a noticeable warming trend through this upcoming weekend with temperatures back in the 50`s by Sunday afternoon. Another mid-level trough will move over the area this weekend but with minimal impacts as it is currently expected to come through dry. && .AVIATION...(For the 00Z TAFS through 00Z Thursday) Issued at 453 PM CST Tue Feb 22 2022 Cold and dry high pressure will continue to build in from the north tonight. The RAP and GFS show some high RH in low levels implying some stratus persisting overnight. However satellite shows clouds upstream to be cumuliform. So think these should fall apart with the loss of daylight. But will keep an eye on this since forecast soundings show such cold temps in the lower troposphere that it wouldn`t take much to saturate. Otherwise VFR conditions should persist. && .TOP WATCHES/WARNINGS/ADVISORIES... Wind Chill Advisory until 11 AM CST Wednesday for KSZ008>012- 020>024-026-034>039-054-055. && $$ UPDATE...Wolters DISCUSSION...Teefey AVIATION...Wolters