Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 02/01/21

Area Forecast Discussion
National Weather Service Charleston SC
1038 PM EST Sun Jan 31 2021 .SYNOPSIS... A cold front will move offshore tonight. High pressure will then steadily build into the region through the middle of the week. Another front could reach the forecast area next weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... As of 1030 PM: KCLX indicated a broad band of light to moderate rain off the coast. To the west, a small band of showers was pushing east across the middle Savannah River valley. Latest run of the HRRR indicates that the upstream convection will continue to track east through the rest of the night, passing over portions of the CWA tonight. I will keep mentionable PoPs through most of the night. Temperatures may cool by 10 degrees by day break Monday, with gradually cooling expected through mid-morning. The forecast will feature adjustments to the hourly temperatures through the rest of the night. AS of 920 PM: The cold front and associated convection has pushed off the GA and SC coast. The forecast will be updated to remove mention of thunderstorms over land, shift winds from the west, begin reducing PoPs from west to east. As of 620 PM: KCLX detected a fine line of reflectivity over inland GA/SC approaching the coastal counties. This feature appeared associated with the position of the wedge front/cold front. Based on radar trends, rainfall rates should increase with the passage of the front. Deeper convection was detected over southern GA, tracking to the NE. It is possible that this activity could track over the coastal GA counties with thunder later this evening. The forecast will continue to indicate greater coverage this evening, with a mention of thunderstorms. Previous Discussion: An upper level low/trough located over the MidWest will deepen/dig tonight as mid-level jetting rounds its base, eventually extending from the Great Lakes to the Gulf of Mexico by late tonight. At the surface, its low pressure component will move across the Ohio Valley, and a cold front with waves of low pressure will develop along the front moving across the forecast area tonight. Light rain will continue through the evening, although it will be patchy in coverage due to some areas stabilizing at the surface with evaporative cooling occurring. Because of this, winds/gusts have decreased slightly with some gusts up to 30 mph expected through the night, mainly along the coastal areas. Heavier showers then look to consolidate into a band that rakes through with the front between 6 and 11 pm. It is also during this time when there could be a few t-storms, mainly south of I-16 in Georgia where the best SBCAPE is situated, albeit no more than 250 J/kg. Given that shear is around 50 kt, there is a risk for a stronger storm or two. SPC has portions of Long, Tattnall, Liberty, and McIntosh counties in a Marginal risk for severe thunderstorms through tonight. Deep moisture wrapping around the surface low will make its way into the area behind the main line of showers. Isolated/scattered showers are possible beyond midnight, especially inland as PWATS still cling to close to 1". Cold air advection as well as a more stabilized environment should limit these showers from progressing further east, however. Rainfall totals are still on track to range from 1/2" to 1", with locally higher amounts targeting mainly the Charleston Tri-County region, as well as in the extreme southeast GA counties where a stronger thunderstorm is possible. Cold air advection will strengthen late tonight/early morning, dropping temperatures into the mid and upper 40s, perhaps near 40F in the extreme inland counties by dawn Monday. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... Monday and Monday night: Aloft, an impressive upper low will continue to deepen and sink southward along the Eastern Seaboard, then begin to shift slightly eastward overnight. At the surface, the forecast area will be caught in the cyclonic flow around the deepening low centered just off the New England/Mid Atlantic coast. Plenty of residual moisture will be in place up to around 10 kft, helping to produce mostly cloudy to overcast skies through the period. Also, with the cold air aloft under the trough/closed low we will see isolated to scattered showers, mainly across southeast South Carolina and the Tri-County region. The best gradient will be aligned across southeast Georgia, supporting frequent west-northwest gusts to around 25 mph. Conditions won`t be quite as breezy the further northeast you go as the isn`t nearly as tight. Overall, it will be a very chilly and cloudy day. Temperatures will likely struggled to reach 50 for much of the forecast area thanks to the persistent cloud cover. The best chance for low 50s will be along the immediate coastal corridor. Overnight lows are forecast to range from the low 30 inland to the mid 30s closer to the coast. Tuesday through Wednesday: Lingering moisture will finally pull away from the area on Tuesday and skies will steadily clear out, becoming mostly clear for Tuesday night and Wednesday. Tuesday actually looks like it will be accompanied by the strongest winds as the tightest pressure gradient lines up right across the forecast area. Frequent gusts to around 25 mph are expected, and we could even see some gusts approach 30 mph. There will be plenty of sun by Tuesday afternoon, but we will still see temperatures right around 50 just about everywhere. Wednesday will only be a few degrees warmer, but fortunately not as breezy. Tuesday night lows should result in a widespread freeze with upper 20s inland and low to mid 30s right along the coast. Lake Winds: Winds will remain elevated across Lake Moultrie through much of the early part of the week. The strongest winds are expected Monday night when gusts could approach 25 knots. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Models start out in good agreement. High pressure will be over the region Wednesday night, moving offshore into Thursday. Expect dry conditions with moderating temperatures on Thursday. Friday and Saturday is when each model shows something completely different. All have a front approaching our area, but they disagree on it`s position and the resulting weather. The best we can do at this point is slight chance to chance POPs Friday into Saturday. More changes will be needed with this part of the forecast. && .AVIATION /04Z MONDAY THROUGH FRIDAY/... Prior to the 0Z TAFs, KCLX detected a fine line of reflectivity approaching the terminals from the west. This feature appeared associated with the position of the wedge front. Based on upstream observations near the wedge front, conditions should gradually fall to MVFR early this evening. Based on MOS and forecast soundings, ceilings should fall well within IFR range to LIFR late this evening into the late night hours. A cold front is expected to sweep west to east across KCHS/KSAV during the pre-dawn hours, shifting winds from the NW. During the daylight hours Monday, NW winds should gusts generally between 20-25 kts with MVFR ceilings lingering. Sub-VFR ceilings could linger at KCHS through Monday afternoon, but prevailing VFR should return Monday night. Winds will be breezy Monday afternoon (especially at KSAV), and then again at both KCHS and KSAV on Tuesday. && .MARINE... Today and tonight: A cold front is expected to pass over the waters around midnight, which will allow winds to veer out of the southwest and then out of the west by early morning, with late night cold air advection to develop. Winds will remain 20-25 kt with gusts up to 20 kt throughout the night, hence Small Craft Advisories are in effect across all waters, including the Charleston Harbor. There will also be period of Gales that will impact the outer Georgia waters tonight, where we have a Gale Warning in effect through most of the night. A Small Craft Advisory will be needed thereafter. Seas will continue to build up to 6-8 feet in the nearshore waters out 20 nm and up to 10 ft in the outer GA waters. After the passage of the front, seas will gradually decrease by a couple of feet. Mariners are also alerted to the potential for a few t-storms tonight in advance of the cold front. Monday through Friday: A tight pressure gradient and cold air advection will support persistent and strong northwest winds Monday through Tuesday night. Conditions will improve considerably on Wednesday and then remain below advisory criteria through the end of the week, though southerly flow could be close to criteria Thursday night and Friday. For Monday, the best gradient and strongest winds will be aligned across the Georgia waters with gusts up to around 30 knots. For the South Carolina waters, winds and seas could actually end up falling below Small Craft Advisory criteria for a period of time. However, we opted to just keep the advisory going for all zones (outside of Charleston Harbor) as a solid surge is expected Monday night. In fact, we could see another period of gales in the outer Georgia waters Monday night and this will be added to the Hazardous Weather Outlook. Solid advisory conditions will prevail through Tuesday and much of Tuesday night. All advisories should come down by midday Wednesday. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory until 2 AM EST Monday for AMZ330. Small Craft Advisory until 11 AM EST Wednesday for AMZ350-352. Gale Warning until 4 AM EST Monday for AMZ374. Small Craft Advisory until 5 AM EST Wednesday for AMZ354. && $$ NEAR TERM...NED SHORT TERM...BSH LONG TERM... AVIATION...NED MARINE...BRM/BSH
National Weather Service Hastings NE
544 PM CST Sun Jan 31 2021 .DISCUSSION...(This evening through Sunday) Issued at 108 PM CST Sun Jan 31 2021 The clearing line is slowly moving across the forecast area this afternoon. The west is already sunny and the temperatures are a little warmer than in the east. As a surface high builds into the area, winds continue to decrease. The clouds in the east have kept the temperatures from warming very much. There are several things going on this forecast period. First will be fog. The next round of fog is expected across the area tonight. Temperatures warming to around or just above freezing have melted a little snow and there is plenty of low level moisture. The low clouds moving out will get out of the area this afternoon/evening, but are near enough that fog could form. The surface high across the area and light winds will allow for temperatures to cool below the current dew points and all this leads to an increase in fog chances for tonight. The HRRR and SREF both have fog across at least portions of the area. The HRRR is mostly in the east while the SREF is over the entire area with the best probabilities in the central part of the forecast area. Already have areas of fog in and that should be a good start, but may need to be increased. The next question will be clearing out the fog on Monday. The HRRR and SREF both have it moving out by mid morning or so, so will keep that for now. During the day Monday, the surface high moves to the east and by afternoon there is some warm advection, especially in the western part of the forecast area. Even with warm advection, the temperatures will struggle to warm significantly because the winds are expected to be light enough that mixing will be minimal. The east will still be cool since there will be some clouds through much of the day. The fog does not end there. Even with the surface high moving to the east, winds are expected to be light. Fog is a possibility again Monday night. There will be a little melting of snow, warm advection over the cold snow and light winds. The fog could begin during the evening and last into mid morning on Tuesday. Even then, the fog chances are not over yet. Temperatures Tuesday afternoon will be a little warmer and there will be more snow melting during the day, combined with light winds Tuesday night and the SREF has good probabilities for fog again. Since this is still a few days away, have kept it just patchy for now. Wednesday will be a little warmer. Winds will be from the south and increase just a little. During the day Wednesday, another system develops to the west and by Wednesday night there will be a cold front that moves through the area. Behind the cold front, there is a chance for some precipitation. It could start as rain early in the evening, but is expected to mix with and change to snow as the temperatures cool off during the evening and overnight. Temperatures remain cool during the day Thursday and most of the area will have snow with some of the southern parts of the area having a rain/snow mix. By Thursday evening, this system is departing and only a little light snow is possible. This ushers in the last of the concerns for the forecast period. Friday will continue to be cool, but by Friday night the next cold front moves through and brings in the coldest air of the season so far. Temperatures Saturday and Sunday will only reach the teens and lower 20s for highs and that could be generous. Lows will be in the single digits and even a little below zero in the north. Along with the cold temperatures, there are some small chances for some snow Friday night through Saturday night. It could mainly be just squeezing out moisture out of the cold air, but with it being so cold it would be fluffy and could accumulate. There is still some uncertainty on the precipitation chances at this time. && .AVIATION...(For the 00Z KGRI/KEAR TAFS through 00Z Tuesday) Issued at 544 PM CST Sun Jan 31 2021 Significant wx: Beginning what could very well be prolonged (48-72+ hrs) of mainly IFR/LIFR VSBYs and CIGs. Tonight: VFR to LIFR. Have deteriorated TAFs for tonight fairly significantly as fog appears likely to develop after 03Z. Exact timing remains a bit uncertain, and some model data suggests EAR could be more on the edge compared to GRI. Nonetheless, expect at least IFR VSBYs, perhaps even LIFR (esp. at GRI), and LIFR CIGs of 200-400ft. Winds will be lgt and vrbl. Confidence: Medium. Monday: LIFR or IFR. Expect LIFR/IFR fog and LIFR CIGs to start the day. With lack of mixing, its very possible that conditions will be slow to improve, even by late morning. Have a return to MVFR VSBYs for aftn, but this could be generous. VSBYs like tank again Mon eve. Lgt and vrbl winds during the morning, bec primarily light out of the SE by aftn. Confidence: Medium. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ DISCUSSION...JCB AVIATION...Thies
National Weather Service Jackson KY
745 PM EST Sun Jan 31 2021 .UPDATE... Issued at 745 PM EST SUN JAN 31 2021 00z sfc analysis shows a slow moving area of relatively deep low pressure passing by just to the northeast of the JKL CWA. This is swinging the winds around to the northwest through the area and bringing in colder air. This system is also starting to wrap its commahead pcpn back into Kentucky - soon to be spreading into eastern parts of the state. Combined, this means mainly light snow developing for our western counties late this evening and spreading east with time through the night. Staggered WWA have been hoisted for this prolonged snow event. Temperatures (and dewpoints) are currently running from the middle and upper 30s in the west to the mid 40s east. Meanwhile, winds are blowing from the west to northwest at 5 to 15 mph with gusts to between 20 and 25 mph at times. Have updated the forecast in the near term to fine tune the PoPs and add in the latest obs and trends for the T/Td grids. These updates have been sent to the NDFD and web servers. && .SHORT TERM...(This evening through Monday night) Issued at 530 PM EST SUN JAN 31 2021 Late this afternoon, an upper level low was centered near the IN and OH border, northwest of east KY with an upper level trough extending south through the MS Valley. Several vort maxes were rotating around the upper level low, one of which is working into East KY at present and likely partially responsible for the area of showers across the southeastern portions of the area, another upstream nearing the confluence of the OH and MS Valley sand another further northwest near the IA/MO border. At the surface, an occluded area of low pressure is centered near the OH River to the east of KCVG with a trailing occluded front south into eastern KY extending south from Fleming County to just east of the I 75 corridor. A sfc trough extends southwest from the low near the OH River. Further to the east, a low pressure system is starting to take shape along the eastern seaboard over the Carolinas. Tonight and into Monday, the upper level low is expected to move slowly east to and be centered near the mid OH Valley region around dawn on Monday and then move to the piedmont region along the eastern seaboard by Monday evening. The lead shortwave trough will move east of the area this evening, with the next two approaching the western portions of the area and merging overnight into early on Monday as they track into the Appalachians. A sfc trough will work across the area overnight to around dawn on Monday, with much colder air working in aloft and at the sfc with this. The column should cool sufficiently that around midnight if not 11 PM, rain should begin to mix with or perhaps change to snow along the western tier of counties and then gradually from west to east and from the higher elevations above 2500 feet down to the southeastern valleys through around dawn on Monday. Sfc temperatures should fall to near if not a little below freezing as this passes. Cold air advection continues through the day with another vort likely rotating across the area during the afternoon. The low level flow will also be upslope west to northwest behind the sfc trough, initially enhancing snow a bit near the escarpment and perhaps the Log Mtns of Bell County, and then as the winds become more northwesterly through the morning into the afternoon, enhancing snow in the southeastern counties generally along or southeast of KY 80 and the Hal Rogers Parkway. Even as the upper low moves further east of the area on Monday night, an additional vort likely work across the area while the low level flow remains upslope with moisture persisting, especially over the southeast and east. Periods of snow or snow showers should continue through Monday night as well, particularly across the south and west, but gradually starting to taper off from northwest to southeast. This is going to be a long drawn out event with snowfall over 30 to 36 hours reaching the 4 to 6 inches range in some of the higher elevations above 2000 feet and perhaps reaching the 4 inch mark along the escarpment as well. HRRR and some of the HREF guidance PMM Snowfall point toward this potential. Intensity will be quite variable as well. However, every 6 hour period snowfall should only average a half of an inch to one inch with locally higher amounts, especially late tonight to early on Monday in the escarpment and late Monday into Monday night in the southeast. With that in mind, the Winter Weather Advisory headline category still fits this scenario due to the long duration event. Some adjustments have been made to the start times based on the latest thinking and in coordination with surrounding offices. The end time has been extended into Monday night or early Tuesday across the south and east as the upslope event should persist during that time. There will be travel impacts at times, with the Monday morning and Monday evening commute likely impacted with the Tuesday morning commute also possibly impacted in the southeast. The long duration 30 to 36 hour totals should average 1 to 4 inches for most locations, generally with higher amounts along the escarpment and in the higher elevations in the southeast. Above 2000 feet, 4 to 6 inches may accumulate with locally higher amounts above 3000 feet. .LONG TERM...(Tuesday through Sunday) Issued at 530 PM EST SUN JAN 31 2021 An active long-term period is in store for eastern Kentucky. Lingering upslope snow showers and flurries will gradually be coming to an end on Tuesday with just some minor accumulations possible over Southeast Kentucky. High pressure brings a brief reprieve on Wednesday before another late week storm system and a potential arctic cold front bring more rain, snow, and colder air. 12z Tuesday-00z Thursday... The period will start off Tuesday morning with a powerful nor`easter centered south of Long Island and its supporting ~532 dam low located over the Delmarva Peninsula. A ridge of high pressure will be located over the Plains and will be supporting a surface ridge spanning from the Texas Gulf Coast to western Ontario. The deep low will only gradually drift toward the Canadian Maritimes through 0z Thursday while the next Pacific trough pushes into the Rockies/Northern Plains and knocks down the ridge over the Central US. This will shunt the surface ridge across the Ohio Valley on Wednesday. In sensible terms, look for lingering snow showers across those higher elevations above 1,500 feet Tuesday morning while a few flurries linger as far back as I-75 and I-64. This activity will gradually diminish through the day and perhaps give way to partial sunshine outside of the highest terrain by the afternoon. Additional accumulations will be minimal, ranging from a dusting north of Highway 80 up to around 1-1.5 inches above 3,000 feet. Even though temperatures are expected to reach the low to mid 30s, a brisk northwesterly breeze at around 8 to 15 mph will make it feel several degrees colder. An upper level disturbance rotating around the departing low is expected bring another uptick in cloud cover and perhaps a few flurries Tuesday night. Tuesday night`s low temperatures are tricky, as any clearing would allow for rapid radiational cooling in the snow-covered valleys; but, if clouds prevail, that cooling potential won`t be realized. Remained close to NBM guidance for now and forecasted lows in the upper teens to lower 20s. Skies should become mostly sunny on Wednesday as the high pressure moves in. Even so, light northwest to westerly flow and the snow cover will keep high temperatures on the chilly side, likely mid to upper 30s for most. 00z Thursday-Sunday... The next upper level trough will initiate a low pressure system in the lee of the Colorado Rockies as it descends onto the Plains mid-to-late week. The models still differ on timing and many of the specifics around this system, but they do bring in milder temperatures for eastern Kentucky and a round of rainfall for Thursday into Friday, along and ahead of the system`s cold front. A brief changeover to snow can`t be ruled out on the tail end of the system. Thereafter, the models and ensembles have latched onto the the potential for an arctic cold front arriving over the weekend with 850 mb temperatures plummeting toward -20C or colder. The GFS keeps the arctic frontal passage rather tame with just some blustery snow showers. The ECMWF and the Canadian show a low pressure system riding along the front and leaving behind a blanket of snow. This push of colder is also air well-supported by the various ensemble means. While there is still plenty of uncertainty, given the run-to-run and model-to-model differences, early next week could be very wintry across eastern Kentucky. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) ISSUED AT 720 PM EST SUN JAN 31 2021 Conditions will continue to gradually deteriorate into the IFR range everywhere this evening. IFR conditions should then generally prevail through the end of the period with some periods of LIFR possible in any heavier snow showers into the day Monday. Ceilings could be down to near or below airport mins for some of that time, as well. With the low pressure system working across the area, periods of rain will occur this evening. Colder air flows into the area from west to east through 12Z, and especially between 06 and 12Z, changing any rain to snow during the night. The snow will then continue through the rest of the period. Winds will be basically locked into the northwest direction through the forecast period at around 10 kts with some periods of lull and occasional gusts to near 20 kts. && .JKL WATCHES/WARNINGS/ADVISORIES... Winter Weather Advisory from 1 AM Monday to 7 AM EST Tuesday for KYZ052-060-080-084>086-104-106>117-119. Winter Weather Advisory from 11 PM this evening to 7 PM EST Monday for KYZ044-050-051-058-059-068-069-079-083. Winter Weather Advisory from 1 AM Monday to 10 AM EST Tuesday for KYZ087-088-118. Winter Weather Advisory from 4 AM Monday to 10 AM EST Tuesday for KYZ120. && $$ UPDATE...GREIF SHORT TERM...JP LONG TERM...GEERTSON AVIATION...JP/GREIF
Area Forecast Discussion
National Weather Service Pocatello ID
133 PM MST Sun Jan 31 2021 .SHORT TERM...Tonight through Tuesday night. Early afternoon satellite imagery was showing a ridge over the region with lingering low clouds along the Montana border near Monida Pass. Looking upstream, a broad upper low was noted edging toward the NW coastal waters. The numerical models show the ridge holding firm over CNTRL Wyoming through Monday evening as short-waves eject from the low off the coast into SW Canada. Starting early Tuesday morning and continuing through Tuesday night, the weakened trough begins to move onshore with increasing moisture impinging on the CNTRL mountains through the day Tuesday and the remainder of SE Idaho Tuesday night. The operational models favor a split in the trough with the NRN branch impacting SE Idaho. With that said, there are some interesting differences between the models with the GFS representing the slowest solution, the NAM being the most progressive, and the ECMWF falling in between. The speed of the solution has a direct impact on the onset of precipitation across the SE mountains. With that said, I have generally allowed the National Blend of Models to drive the boat here as it would taken into account all the variability. Temperatures are expected to run at or slightly above normal through Tuesday and then much above normal Tuesday night due to the incoming trough. Huston .LONG TERM...Wednesday through next Sunday. Fairly widespread precip should be ongoing Wed AM, likely predominantly snow or all snow by that time as temps diurnally cool, shutting down from NW to SE Wed afternoon/eve as a cold front crosses the region. Breezy conditions are also possible, with perhaps some pockets of blowing snow. Our storm total snowfall forecast has changed little, with higher- elevation locales that normally benefit from a WSW flow potentially picking up advisory-level totals over 5" (esp the Sawtooths and Galena/Banner Summits), with generally an elevation-dependent 1-4" across the srn/ern highlands and a bit more in the mntns surrounding the Teton Valley. Totals are still coming in at generally less than an inch for the Snake Plain, ern Magic Valley, and some srn highland valleys where precip will be lighter and also fall partially as rain prior to Wed AM. High temps Wed won`t really have a fair shot a fully "topping out" and succeeding at life between the cloud cover and the cold front, generally reaching the 30s. Starting Thurs, SE ID will be positioned directly in an active storm track sandwiched between a building ridge of high pressure over the Pacific and a longwave trough over the cntrl/ern US, with both synoptic features nearly stationary. This storm track will be governed by a cool, moist, NW flow, with occasional disturbances providing foci for precip chances. Temps will thus be near to below normal into the weekend. The first disturbance riding this flow is still forecast to drop SE across the area Thurs night and Fri, bringing light snow that should favor the ern/srn mntns. This disturbance remains pretty progressive, and has trended weaker/less amplified in today`s 12z model suite, more of a ripple in the pressure height field than a bonafide organized shortwave. (In fact, this feature isn`t picked up at all by 500mb cluster analysis.) Every QPF cluster DOES include over 0.10 inches QPF for at least some portion of our ern highlands (if not greater real estate), so a shot of more organized moisture is certainly there with a bit of a mid-level vorticity max/jet embedded in the flow. A range of solutions is noted in the GFS/EC ensemble members as we check snow for various points across the forecast area, but even the highest accums are light-moderate everywhere with that ern highland preference evident for highest totals...some members are coming in as high as 3-4" for Driggs (so likely more at higher elevations). We may see a break on Sat, followed by a variety of potential model solutions regarding the occurrence/timing of our next disturbance Sun or Mon. By this time, 500mb cluster analysis has 2 clusters (55% of the members, GFS-heavy) supporting an increasing eastward influence of the Pacific ridge which may tend to nudge the active storm track east of our area, while another 2 clusters (about 45% of the members, EC/Canadian-heavy) maintain the status quo. Thus, forecast confidence remains high in continued near to below normal temps, but is low in sensible wx details Sat and beyond. High-impact storms currently seem unlikely. Low temps may reach the single digits above to single digits below zero by the weekend for some areas, depending on cloud cover. - KSmith && .AVIATION...A ridge of high pressure will remain the dominant synoptic wx feature across SE Idaho both today/Mon, with light winds and a SLIGHT drying trend noted in the guidance over the period as well. Fog/low stratus development last night/early this AM generally followed the HREF flavor with KIDA remaining just south of the main shield. Tonight/Mon AM, development is much more limited to non- existent across ALL guidance with slightly wider sfc temp/dew point depressions advertised. Given recent rain/snow, we can`t COMPLETELY rule out some development, esp near water sources, but we have no strong basis to include it in any TAFs at this time. The HRRR suggests (unsurprisingly) KIDA/KDIJ would be the best candidates, but both terminals fared well last night, and again we are trending a bit drier. In other news, the HRRR suggests a southerly downslope wind MAY develop at KPIH this afternoon at up to 10kts, but we`re not really seeing signs of this just yet and all coarser guidance maintains a NE down-plain flow, so will stay the course and monitor. Also, high-res guidance tries to creep showers in toward KBYI/KSUN by Mon AM (WELL in advance of the next system), but this is not supported across deterministic models (little upper-level support/ lift) and has been dismissed for now. The result of all of this is mostly one-liner TAFs (except KSUN/KDIJ for wind shifts) with no widespread aviation impacts. Overall confidence is high, with again lower confidence in patchy fog/low stratus. It still appears precip with our next system should hold off until Tue night. - KSmith && .PIH WATCHES/WARNINGS/ADVISORIES...None. && $$
Area Forecast Discussion
National Weather Service San Diego CA
110 PM PST Sun Jan 31 2021 .SYNOPSIS... High clouds will thicken tonight through Monday as moisture aloft increases from the southwest. For Monday, it will be mostly cloudy with sprinkles, or scattered light showers at times. The best chance for anything measurable will be over the mountains. Meantime, low pressure off the coast of western Canada will slowly sink south along the West Coast, bringing a chance of showers on Wednesday. Dry weather and offshore flow is forecast for the latter part of the week. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... Satellite imagery midday showed high clouds streaming NE across the State. After numerous large breaks this morning, they were consolidating early this afternoon, and look even more solid well off to the SW, so look for more thickening overnight. Surface pressure gradients have been moderately offshore all day, with the offshore wind-prone areas of the mtns/passes reporting E-NE winds of 20-25 MPH with gusts 30-40 MPH. Temperatures were running some 7-12F above values observed at midday yesterday. A weak ridge over the Southwest will drift east today, as a longwave trough sets up off the West Coast. At the same time, a little farther to the west, a ridge will be amplifying over the EastPac along 140W. The ridge is now forecast to drift east this week, which will crimp the effects of the trough. Most deterministic model solutions are now coming up dry over SW CA midweek, as the trough gets squeezed by the ridge and comes inland farther south. Shower chances remain in the forecast for Wednesday, but are lower, with a downward trend. The GFS 12Z ensemble member solutions remain predominantly wet, while the ECMWF is mostly dry and the NAM12 deterministic runs are mostly dry. The forecast proximity of the ridge to the West Coast will now limit chances for significant precipitation this week, however, a considerable amount of subtropical moisture will still get entrained in the SW flow aloft for the next 24-36 hours. This could still bring us some light precipitation, especially on Monday. For now, measurable precipitation, if any, is expected on the higher mountains, while lower elevations will likely only see sprinkles at times. This has been advertised by several HRRR runs and the WRFEMS as well. Frequently, advecting moist airmasses from the SW of San Diego are fraught with uncertainty, since we generally only have satellite interpretations of the atmospheric structure. For now, we will accept the current model depictions, keeping small measurable amounts over the mountains and just sprinkles at lower elevations. In any case, amounts will be very light, since there is little forcing to act on this moisture. Once we get the weakening trough out of the way midweek, the latter half of the week looks dry with predominantly offshore flow and seasonally mild temperatures. The block forming over the far EastPac late this week may not be around too long though. The 12Z medium range guidance from the EC/GFS both show it breaking down next week with quite a bit of spread in ensemble solutions as well. && .AVIATION... 312100Z...SCT-BKN clouds with bases 10,000-15,000 feet MSL to continue through Monday. Breezy east-northeast winds expected across mountains and adjacent foothills through tonight, with gusts of 20- 30 kts. Winds will diminish overnight. && .MARINE... No hazardous marine conditions are expected through Tuesday. Increasing northwest winds may develop on Wednesday with gusts near 20 kts and combined seas of 6-7 feet possible across the outer waters. && .SKYWARN... Skywarn activation will not be needed today. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...NONE. PZ...NONE. && $$ PUBLIC...10 AVIATION/MARINE...Connolly
Area Forecast Discussion
National Weather Service Tulsa OK
951 PM CST Sun Jan 31 2021 ...UPDATE... .DISCUSSION... Back edge of low clouds hasn`t made much eastward progress this evening, and recent HRRR output suggests clearing may be a bit slower than previously expected. Have tweaked sky cover some for the remainder of the night. && .PRELIMINARY POINT TEMPS/POPS... TUL 28 50 31 57 / 0 0 0 0 FSM 30 50 28 56 / 0 0 0 0 MLC 28 51 31 58 / 0 0 0 0 BVO 27 47 27 56 / 0 0 0 0 FYV 28 45 24 54 / 0 0 0 0 BYV 28 43 25 52 / 0 0 0 0 MKO 28 47 29 55 / 0 0 0 0 MIO 28 45 26 53 / 0 0 0 0 F10 28 50 31 58 / 0 0 0 0 HHW 29 53 32 56 / 0 0 0 0 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...None. AR...None. && $$ SHORT TERM...18