Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 05/07/17

Area Forecast Discussion
National Weather Service Taunton MA
1006 PM EDT Sat May 6 2017 .SYNOPSIS... Below normal temperatures and occasional unsettled weather are expected into this coming week as low pressure at the surface and aloft remains stalled in the vicinity of New England. Some moderation in temperature and less risk of showers Wednesday through Friday but still considerable lingering cloudiness and temperatures probably at least a little below normal. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Shortwave moving north across the region generating another batch of showers. Radar trends and 00Z HRRR suggest scattered showers through at least midnight, possibly an hour or so longer. Second area of showers popped over the Hudson Valley this evening, thanks to cold air aloft and resulting instability as well as surface trough bringing low level convergence. This area will affect the Berkshires and parts of the CT River Valley through midnight. Expect diminishing clouds overnight as drier air works in. Dewpoints fall through the 40s and temperatures fall to the upper 40s and low 50s. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/... Sunday into Sunday night... Turning cooler with continued shower chances. Going to have to watch continued vort-lobe action round the broader occluding low especially as they cyclonically dive S latching into deeper moisture off the NW Atlantic and rotate back N. Forecast models suggesting such activity skirts E/SE areas of S New England with the development of a meso- low along offshore regions of baroclinicity. However there is still a fair amount of low to mid level moisture across the interior and closer to the center of the low in regions of favorable ascent, more so along the W slopes of high terrain. We may see additional shower activity just by way of boundary destabilization beneath the cold pool as was observed W earlier today (Saturday) across Upstate NY and PA. Will forego a mention of thunder for now, if any thinking isolated. Highs upper 50s to low 60s. A bit challenging to forecast the spatial extent and timing of outcomes with greater specificity, so will go with chance PoPs over the entire S New England forecast area. Confident will see scattered to broken cloud decks rotating around the region parent with the low given the abundance of low to mid level moisture along with cooler air wrapping into the region, this as winds become more westerly. Lapse rates steepening with cold air advection within the low levels should see some gusty winds, especially during diurnal heating. One last note, as we go into the overnight period, given continued low level moisture along with cold air advection, more than likely we`ll still see some shower activity along the W slopes of high terrain. H925 temperatures down around -2C, some shower activity may fall in the form of wet snowflakes. Very atypical pattern for early May when normal highs range around the mid 60s. Will also have to monitor for the potential of frost advisories over CT and S of the I- 90 corridor. Lows in the 30s. Coolest over higher elevations. && .LONG TERM /MONDAY THROUGH SATURDAY/... */ Highlights... - Cooler than normal temperatures and a risk of showers from time to time look to be the weather theme for early in the coming week - May see a little moderation in temperatures and less risk of showers Wednesday through Friday */ Overview... The circulation over the USA will be dominated at the start of forecast period by closed upper lows in the Northeast and Southwest. Our weather will largely be modulated by large scale blocking upper flow features. The Northeast upper low will be slow to move given the blocking pattern. As noted in the prior discussion, computer models have a tendency to move closed systems out too fast. Hence, the sensible weather is likely to be slow to change over our area this coming week. Although inherent uncertainty being late in the forecast period, a consensus of models depict the upper low over New England and southeast Canada splitting. The northwest upper low may rotate back through the Great Lakes and possibly phase with energy from the Southwest USA cutoff low that lifts slowly northeast late in the week. This may spawn a surface low off the mid Atlantic states. If it tracks close enough to the coast, we experience a a cool steady rain this coming weekend, but this remains uncertain so far out. We suspect that the models will likely depict in their operational and ensemble runs a modification of the upper flow as we get closer to the end of the week. The combination of considerable cloudiness, a few showers from time to time, and 850 mb temperatures within a few degrees of 0C will likely keep temperatures below normal for most of the week, although some modification is expected from early to late week. */ Details... Monday...Will likely be challenging for temperatures to rise out of the 50s given 850 mb temperatures -3C to -4C across most of southern New England and considerable cloudiness underneath the broad upper low. Any sunshine would likely induce some convection and then more cloud formation in the moist air mass. Although the air mass remains relatively moist, there is not organized forcing and so plan to keep POPs relatively low. Monday night...Will be cool but should be enough clouds to inhibit radiational cooling. Tuesday...With cyclonic flow and upper low in the vicinity anticipate similar conditions as Monday with considerable cloudiness. Evidence of a short wave trough passing along the base of the closed upper low center may induce scattered showers. Air mass temperatures moderate a little but still expect to remain below normal. Wednesday through Friday...Upper heights build a little Wednesday and Friday and looks as though may see some subsidence and less chance of showers. Temperatures at 850 mb slow moderate to a few degrees above 0C, but will likely have trapped moisture and a fair amount of cloudiness. Thus, may see temperatures a little warmer but still probably at least a little below normal for the time of year. Saturday...Energy lifting out of the Southwest USA may reach the mid Atlantic coast and possibly spawn surface low pressure off the coast south of New England. There may be phasing with a northern stream lobe of low pressure that swings towards our region but too soon to be sure. Saturday has the potential to be or become cool and wet with a raw northeast wind. Will go for chance POPs at this time given inherent uncertainty on how all of this will play out on day 7. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday Night/... Scattered showers early, but with drier air moving into the area we expect mostly VFR conditions. Even so, a few showers will be sufficiently moistening to bring a period of MVFR cigs. Expect an overall drying trend overnight with decreasing sky cover by morning. South winds turn from the southwest after midnight. Sunday into Sunday night... Leaning towards BKN-OVC low-end VFR cigs mixed in with MVFR especially over the high terrain. SCT SHRA activity though highest confidence over E/SE MA. SW winds which will be breezy at times, gusts up around 20 kts. More than likely terminals will waver on prevailing conditions as multiple CIG decks at various levels through MVFR to low-end VFR exist. Can not rule out some IFR. KBOS TAF...Partial clearing ongoing. Some stronger S gusts potentially emerging up around 25 kts. Short-lived. Expected low-end VFR / MVFR CIGs to fill back in around 21-22z, lowering to IFR overnight. Chance SHRA. Could scour by morning. KBDL TAF...Gusts up around 30 kts continue with SCT-BKN low-end VFR cigs, through 21-22z. Thereafter BKN-OVC low-end VFR / MVFR CIGs and SHRA move in from the S. IFR CIG conditions possibly developing over- night. Could scour by morning. Outlook /Monday through Thursday/... Confidence...Moderate. Mainly VFR conditions with scattered areas of MVFR ceilings possible from time to time, especially over higher terrain. Visibility may briefly lower to MVFR in widely scattered showers Monday and Tuesday. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Sunday Night/...Moderate confidence. Low pressure wobbling across Upstate NY into S Canada. Round which we`ll see continued low clouds and showers at times along with breezy S winds becoming more W. This results in the continuance of rough seas over the waters given a S/E swell. Some visibility issues with any shower activity. SMALL CRAFT ADVISORIES continue with wave heights of 8 to 10 feet on the outer waters and gusts up around 25 kts at times, more importantly along the near-shores for Sunday. Outlook /Monday through Thursday/... Monday...Confidence is moderate. Left over swell above 5 feet may linger into Monday morning across the outer coastal waters. Tuesday through Thursday...Confidence is high. Winds and seas are expected to remain below Small Craft Advisory levels. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ231>235-237- 250-251-254>256. Small Craft Advisory from 2 AM to 6 PM EDT Sunday for ANZ230. Small Craft Advisory until 6 PM EDT Sunday for ANZ236. && $$ SYNOPSIS...WTB/Sipprell/Thompson NEAR TERM...WTB/Sipprell/Thompson SHORT TERM...Sipprell LONG TERM...Thompson AVIATION...Sipprell/Thompson MARINE...Sipprell/Thompson
Area Forecast Discussion
National Weather Service Charleston SC
1022 PM EDT Sat May 6 2017 .SYNOPSIS... A cold front will move off the coast Sunday morning. High pressure will then build in through early next week. A backdoor cold front will stall to the north during mid week, before a stronger cold front impacts the area late in the week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... As of 1015 PM: Recent images from KCLX radar indicated a fine line, likely the cold front, sliding south across the Midlands toward the Lowcountry. To the north, the stronger showers were tracking east, with weak showers extending west across northern GA. Based on the radar and IR satellite trends, I will increase the coverage of sprinkles across the inland SC counties for late this evening and early Sunday morning. In addition, I will update the sky to increase mid evening cloud cover, sliding the line between clear to mostly cloudy around a county south. As of 735 PM: A band of showers was spreading across the Midlands of SC. Sfc observations below the showers indicate that rainfall rates generally ranged from 0.01-0.05/hr. The greater reflectivity values were tracking east, poised to move north of the forecast area. However, weaker showers to the west still appear in line to brush the northern portion of the forecast area late this evening. Based on the satellite and radar trends, I will adjust sky and will continue to mention sprinkles to the north. Temperatures and winds appear in good shape. As of 630 PM: A well defined mid level vort max was rippling over the southern Appalachians. At the sfc, low pressure was pushing across the Midland, with a tailing cold front extending west across northern GA. A band of showers and thunderstorms have developed along and ahead of the low and associated cold front. Recent radar images indicate that the leading edge of the convection was weakening as it moved east. However, most recent runs of the HRRR indicate that a few showers or sprinkles will reach the inland SC counties before dissipating. The current forecast looks good, I will update temp, sky, and winds to align with latest obs. Previous discussion: An upper disturbance will rotate around the base of large east coast upper low, passing through far northern GA and SC. A cold front will approach from the north around midnight. Models indicate some light showers with this front, but they will be weakening/dissipating as they make their way to our far northwest counties, especially in the vicinity of the Santee Cooper Lakes. We maintained silent POPs for these locations and hinted at some sprinkles for our NW tier for a few hours. Measurable rainfall will be hard to accomplish. The remaining parts of our area will stay dry. The more noticeable things with this front will be a brief increase in clouds, mainly inland and over the SC zones. Winds could increase a bit overnight with the front, but nothing too significant. Lows will again be in the lower to mid 50s most areas, warmer at the immediate coast. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... Sunday through Tuesday: The mid/upper level pattern will essentially remain the same through the period as the forecast area finds itself within the larger scale circulation around the deep upper low over the Northeast. This will result in persistent west to northwest flow aloft. At the surface, a cold front will move away on Sunday and high pressure will build into the region through Tuesday. Plentiful dry air will dominate the period, and the forecast is rain free. Instead the main points will be warming temperatures and breezy conditions Sunday and Tuesday. Temperatures will warm Sunday and Monday, but remain below normal with highs in the upper 70s for most areas. Then by Tuesday there will be enough downslope and compressional warming to produce a big jump to highs in the mid to upper 80s. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Ridging over the Gulf of Mexico and MS valley during mid week will slide east, but flattens overhead Thursday, before giving way to a decent short wave that ejects from the SW states and reaches our area late in the week. Simultaneously at the surface a stationary front will remain off to the north, as high pressure prevails to the south, before a cold front associated with the short wave arrives late in the week. With no influx of either Gulf or Atlantic moisture, there remains no chance of rainfall until the approach of the cold front late in the forecast period. 850 mb temps are as much as 2 or maybe 3 standard deviations above normal, so we`re back well above normal in regards to both max and min temps through the period. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... VFR through 0Z Monday. A cold front is forecast to reach KCHS around 6z, likely bringing a return of gusty west winds. NAM forecast soundings indicate that gusts may continue through the pre-dawn hours. KSAV and KCHS should veer winds from the WNW during the early daylight hours on Sunday. Wind gusts should range from 16-20 kts through the afternoon hours. Extended Aviation Outlook: VFR. && .MARINE... Tonight: Small Craft Advisories are in effect for all of the coastal waters tonight and for the CHS harbor into this evening. Winds may ease a bit before sunset, only to increase again this evening and overnight as a cold front quickly moves through the area from north to south. Seas will respond by peaking after midnight. The highest waves are expected across the outermost portion of the Charleston waters and for the 20-60 nm GA waters. Sunday through Thursday: A cold front will pull away on Sunday and high pressure will gradually build in thereafter. Winds will start off elevated Sunday morning, but any remaining Small Craft Advisory conditions will end. Northwest to west winds in the 15-20 knot range will prevail through the day. Conditions will become increasingly tranquil through Monday as the surface high passes just to the west. Then by Tuesday the gradient will tighten as a backdoor front approaches from the north. Winds will increase and could be 15-20 knots at times, with some potential for Small Craft Advisory conditions into Thursday. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory until 7 AM EDT Sunday for AMZ350-352-354. Small Craft Advisory until 10 AM EDT Sunday for AMZ374. && $$ NEAR TERM...NED SHORT TERM... LONG TERM... AVIATION...NED MARINE...
National Weather Service Jackson KY
1036 PM EDT Sat May 6 2017 .UPDATE... Issued at 1036 PM EDT SAT MAY 6 2017 Based on the latest NAM12 and HRRR model runs, and the latest radar imagery, decided to remove precipitation from the forecast for the rest of the night. It appears that any lingering rain showers will remain east of the forecast area. Skies will continue to gradually clear overnight, with mostly clear to partly cloud conditions expected across the area by 12Z Sunday. The hazardous weather outlook was also updated to remove mention of thunderstorms for tonight as well. UPDATE Issued at 736 PM EDT SAT MAY 6 2017 Made a few updates to the forecast. First, updated the zone forecast text product to remove any afternoon periods or wording, and replaced all that with current timing and wording. Also decided to let mention of thunder to go ahead and drop out of the text forecast product, as radar and lightning data indicate that eastern Kentucky should remain thunder free for the rest of the evening. Still expecting the rain to slowly taper off and be out of the area between 5 and 6Z tonight. Lastly, ingested the latest hourly data into the forecast grids freshen up the forecast elements with new obs and to establish new trends. && .SHORT TERM...(This evening through Sunday night) Issued at 328 PM EDT SAT MAY 6 2017 Main batch of rain continues to push off to the southeast and will be exiting our southeast counties over the next hour. Scattered showers, and maybe a thunderstorm or two, will continue to develop as breaks occur in the clouds and low level lapse rates steepen. The showers will be driven by the sun and will die by or shortly after sunset leaving decreasing clouds from west to east overnight. There is a little bit of uncertainty regarding fog/frost potential tonight. With clearing skies, temperatures will fall into the 30s for most locations, and potentially cold enough for some frost in our western counties, which will clear first. The problem is that a light breeze will stir through much of the night and if winds do go calm, fog will want to form with wet ground after the recent rains. With this in mind, think frost will stay patchy at worst tonight and a frost advisory will not be issued. High pressure and a drier airmass will build into the region Sunday and Sunday night. Despite plenty of sun tomorrow, highs will only reach around 60. Temperatures Sunday night should then drop off quickly and head toward dewpoints which will be in the 30s, and even some upper 20s over northeast Kentucky. However, models indicate that some mid level clouds will likely move overhead at times and winds may also stir much of the night. So, this complicates our low temperature and frost potential forecast but at least patchy frost is again likely, especially over northeast Kentucky. .LONG TERM...(Monday through Saturday) Issued at 328 PM EDT SAT MAY 6 2017 The period begins with a very blocky upper air pattern in place across North America with deep closed lows centered in southwest Quebec and near or just south of California. Upper level ridging will extend from the western Gulf of Mexico into central Canada. This pattern will only slowly change with the upper low in the northeast possibly splitting with a low retrograding into Ontario, and the upper low in the southwest U.S. gradually opening up and moving east. At the surface there will be a northwest-southeast oriented front separating the cooler air to our northeast and warmer air to our southwest. Initially this front will be to our southwest, but it will move northeast as a warm front. However with the blocky pattern in place the front will likely stall near our vicinity on Tuesday, and remain somewhere in our vicinity into the latter part of the week. The exact placement of the front will have a big influence on our sensible weather, and it is uncertain at this point where the front will be each day. With the nearness of the front and the uncertainty of its exact position for most of the week, will need to carry shower chances for the entire week, with thunderstorms possible from Tuesday on. By end of the week, the upper low in the southwest will have opened up and moved east, possibly getting absorbed into the eastern North America trough by next weekend. As the southwest upper low moves east it will induce surface low development. With this stronger system expected to affect the area late in the week, rain chances will be on the increase for the latter part of the week. As far as temperatures go, temperatures will warm through the first part of the week as the warm front moves into the area and then stalls. With the passage of the late week system, cooler air will return for the end of the forecast period. && .AVIATION...(For the 00Z TAFS through 00Z Sunday evening) ISSUED AT 736 PM EDT SAT MAY 6 2017 Isolated rain showers should continue to move across the area this evening, and steadily taper off as the night wears on. Eastern Kentucky should be free of rain by 6Z tonight. The TAF sights should experience VFR conditions with scattered to broken middle level cloud cover move from northwest to southeast across the area for the next few hours. The clouds should scatter out nicely this evening, giving way to mostly clear to partly cloudy skies by 8Z tonight. Winds will generally be out of the west to northwest at 5 to 10 mph through around 4Z before slackening. Sunday should feature mostly clear skies, northwest winds at around 10 mph with some gusts of up to 20 mph possible, and dry conditions for all the TAF sites, as high pressure settles over the region. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AR SHORT TERM...ABE LONG TERM...SBH AVIATION...AR
Area Forecast Discussion
National Weather Service Memphis TN
800 PM CDT Sat May 6 2017 .UPDATE... Updated to remove evening rain chances. && .DISCUSSION... Weak lift and the lack of low level moisture ahead of a passing cold front will produce only patchy cloud cover this evening across portions of the Midsouth. So removed evening rain chances accordingly. The other forecast parameters are currently on track. JAB && .PREV DISCUSSION... /issued 251 PM CDT Sat May 6 2017/ DISCUSSION...Surface analysis this afternoon places a ridge of high pressure over Texas with a weak cold front beginning to enter portions of Northwest Tennessee. As of 2 PM CDT, temperatures across the Mid-South are in the 70s at most locations. A weak cold front will drop through the Mid-South through this evening. Short term models indicate there may be a potential for some limited instability to produce isolated rain showers across portions of West Tennessee and North Mississippi, especially near the Tennessee River. Otherwise, most areas should remain dry tonight. A ridge of high pressure is expected to build in behind the front bringing rain free weather to the Lower Mississippi Valley for the remainder of the weekend through next Wednesday. Long term models indicate the next chance for showers and thunderstorms will come Wednesday night through Friday as a mid- level trough moves through the region. && .AVIATION... 18Z TAFs VFR to prevail through the next 24 hours. A weak cold frontal passage will bring midlevel clouds and perhaps isolated SHRA near sunset east of MEM. Light winds prevail thereafter, as a surface high settles in. HRRR and LAV guidance showing nil chances of radiational fog, some overnight MVFR visibility may be added to MKL and TUP TAFs in a later update. PWB && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$
Area Forecast Discussion
National Weather Service San Francisco Bay Area
857 PM PDT Sat May 6 2017 .SYNOPSIS...Cool and breezy conditions will persist though the remainder of Saturday evening. There is also a slight chance of showers across the southeastern portion of our region overnight, with showers chances also lingering across the far south into Sunday. Otherwise, expect warmer weather on Sunday along with lighter winds. Dry weather with seasonable temperatures are forecast for Monday and Tuesday. Cooler conditions return by the middle of next week. && .DISCUSSION...As of 8:55 PM PDT Saturday...Saturday was a cool and blustery day across much of our region, with high temperatures mostly in the upper 50s and much as 10 degrees cooler than average for the date. Coastal and higher elevation locations were buffeted by northwest winds that gusted as high as 40 mph. Winds have been gradually subsiding this evening and will continue to decrease overnight. The upper low responsible for our cool and blustery weather is currently centered to our south near Point Conception, and is moving slowly to the southeast. Widespread showers and isolated thunderstorms developed over southern and eastern California this afternoon. Current radar shows all precipitation remains to our south and east, although an area of showers that had developed over the Sierra this afternoon is currently moving to the west and directly towards the East Bay. That 00Z NAM shows this shower activity taking a turn to the southwest and tracking across southeastern Santa Clara County by late this evening and eventually into Monterey and San Benito Counties later tonight. The HRRR forecasts all precipitation overnight to remain south of Santa Clara County. In any case, if shower activity does make it into our area overnight, rainfall amounts are expected to be very light. Finally, the airmass is not sufficiently unstable for thunderstorms anywhere in our area this evening, and a forecast update was completed earlier to remove thunderstorm chances. As the upper low continues to move slowly to the southeast overnight and into Sunday, shower chances in our area will continue to diminish. Only far southern San Benito County and southeast Monterey County will continue with a chance of showers on Sunday and mainly during the morning hours. Otherwise, Sunday is expected to be a dry day under partly cloudy skies with temperatures about 5 to 7 degrees warmer than today. Also, winds on Sunday will be much lighter compared to the past two days. An upper ridge is forecast to build across northern California on Monday and Tuesday. Temperatures on those two days are expected to be near normal at the coast and slightly warmer than normal inland. As the boundary layer become more stable early in the work week, look for a marine layer to redevelop, resulting in increasing areas of night and morning low clouds and fog. Warmer temperatures early in the week will be short-lived as the models agree that an upper trough will settle in along the West Coast during the second half of the week and into next weekend. Temperatures will cool beginning Wednesday and then likely remain cool for several days thereafter. Precipitation with this next trough is forecast to remain to the north of our area, so we can generally expect dry, cool and locally breezy conditions during the extended portion of the forecast. && .AVIATION...As of 5:53 PM PDT Saturday...VFR. A closed mid level low currently located 50 miles southwest of Santa Maria will continue to move southward tonight into Sunday. Easterly mid-upper level winds north of this low center will pull residual cloud cover westward off the Sierra Nevada over the Central Valley and toward the coast tonight. Vicinity of KSFO...VFR. Gusty westerly winds this evening becoming light southeast Sunday morning. Westerly winds redevelop Sunday afternoon. SFO Bridge Approach...Similar to KSFO. Monterey Bay Terminals...VFR. Gusty winds will gradually decrease this evening. Onshore winds redevelop late Sunday morning and afternoon. && of 01:45 PM PDT Saturday...Strong northwesterly gale force winds will continue tonight and into tomorrow. Gale force gusts will occur with isolated low end storm force gusts possible, especially along and near the Big Sur and Sonoma coasts. This will be a prolonged wind event with a long fetch for combined seas to build in excess of 15 feet. Mariners should take action now to prevent life and property damage for this strong gale. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...High Surf Advisory...Entire Coast. SCA...Pigeon Pt to Pt Pinos 0-10 nm from 10 PM GLW...Pigeon Pt to Pt Pinos 0-10 nm until 10 PM GLW...Pt Pinos to Pt Piedras Blancas 0-10 nm until 10 PM GLW...Pt Arena to Pigeon Pt 10-60 nm SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm from 10 PM GLW...Pigeon Pt to Pt Piedras Blancas 10-60 nm GLW...Pt Arena to Pt Reyes 0-10 nm GLW...Pt Reyes to Pigeon Pt 0-10 nm SCA...Rough Bar Advisory for SF Bar until 4 AM SCA...Mry Bay SCA...SF Bay until 10 PM && $$ PUBLIC FORECAST: Dykema AVIATION: Canepa MARINE: DRP Visit us at Follow us on Facebook, twitter, and youtube at:
Area Forecast Discussion
National Weather Service Raleigh NC
950 PM EDT Sat May 6 2017 .SYNOPSIS... An upper level low pressure trough will cross the region tonight through Sunday morning. Cool high pressure will build in from the northwest through Monday. A warm front will move into the area from the southwest on Tuesday and then stall over the Carolinas through mid week. && .NEAR TERM /through tonight/... As of 950 PM Saturday... Patchy light showers persist across the area, driven in part by low level warm air advection ahead of a sharpening 850 mb trough slated to cross the CWA tonight, and an upper divergence maximum in the left exit region of a 100+ kt jet diving down from Ontario through the Midwest into SE TN. The HRRR has done a fairly good job so far, focusing the most widespread/heaviest precip just to our south across W/N SC, within a band of low level mass convergence featuring a WSW low level jet and where mid level DPVA is strongest. This band of vorticity will continue to streak across the NC/SC border and into eastern NC overnight, so will stick with chance pops persisting overnight, translating east and increasing a bit late as we head into Sun morning. Thunder chances appear slim, but a few sporadic strikes are certainly possible given the presence of some saturation and lift in the -10C to -20C layer on RAP soundings for a brief period overnight. Expect skies to gradually clear out late tonight as the mid level trough axis shifts to our east, with low level downslope flow and rapidly rising mid level heights. Lows from the low-mid 40s west (clearing and CAA) ranging to around 50 in the east, where clouds will hold on through daybreak Sunday. -GIH Earlier discussion from 100 pm: Convection is expected to re-develop over and/or propagate downstream into west/southwest portions of the state by mid/late afternoon as another potent shortwave (digging SE through eastern KY/TN at 17Z) rounds the base of the trough over the Carolinas. This second round of activity will better coincide with peak heating and will likely be more intense than convection this morning, and an isolated thunderstorm cannot be ruled out in the SW Piedmont late this aft/eve. Diurnal destabilization will be limited in nature this afternoon as the mixed-layer deepens and the low- levels dry out, as will potential instability (theta-e neutral w/height). As a result, severe weather is highly unlikely in central NC. At most, convective wind gusts up to ~40 mph will be possible in the SW Piedmont, Sandhills and Triangle area late this afternoon as low/mid-level flow strengthens in advance of the shortwave in the presence of a relatively deep /well-mixed/ boundary layer invof peak heating. The latest convection allowing models indicate shower activity will pivot from a W-E orientation to a SW-NE orientation after 00Z. As a result, precip chances will initially be highest along/south of Hwy 64 late this afternoon in the W/SW Piedmont, with activity lifting NE toward the Triangle and expanding along/east of the I-95 corridor AOA 00Z as the shortwave begins to eject NE toward the coastal VA/NC border. Shower activity should end from west-east in the coastal plain shortly after midnight. Challenging temperature forecast given ongoing shower activity /evap cooling/ and cloud cover, with additional convection and cloud cover expected by late afternoon. Will reduce highs this afternoon by several degrees, to the lower/mid 60s. Expect lows tonight in the mid/upper 40s, coolest NW where skies will clear earlier. -Vincent && .SHORT TERM /SUNDAY AND SUNDAY NIGHT/... As of 100 PM EDT Saturday... Although a short period of sprinkles cannot be completely ruled out in the far NE Coastal Plain early Sun afternoon in assoc/w additional shortwave energy on the western periphery of the upper level trough as it begins to offshore, dry conditions will otherwise prevail with a dry W/NW flow throughout the column. Expect mostly sunny skies with highs in the upper 60s/lower 70s. With a drier airmass in place, clear skies, and calm winds, optimal radiational cooling should allow for relatively chilly low temperatures Monday morning, in the lower to mid 40s. -Vincent && .LONG TERM /MONDAY THROUGH SATURDAY/... As of 140 PM EDT Saturday... Continuation of strongly negative H5 height anomalies associated with the deep lower over the Northeast/New England will result in another cool and dry day on Monday. The persistent omega block will begin to shift eastward Tue-Wed, with models showing the low splitting over the NE US/Southern Canada by Wednesday, with central NC under the increasing influence of the shortwave ridge building in from the west. Expect gradual warming as heights aloft increase. Rain chances also look to be on the increase, with models showing the potential for episodic-ridge riding disturbances in NW flow aloft to support scattered showers along a quasi-stationary frontal boundary forecast to extend from the Upper MS valley SE invof the Carolinas. The exact location of this front is the next forecast challenge and will ultimately be the key wx feature that will go a long way in determining temperatures and rain chances Wed-Thu. For now will show a rather sharp north to south temperature gradient, coolest across the north where low clouds and rain could support wedge-like air mass, while maintaining slight to low chance pops everywhere due to uncertainty/low- predictability with the NW flow disturbances and the location of the front. Meanwhile, the former closed low over the SW US will eject eastward across the central US as an open wave. This wave will approach the area from the west on Friday, where it will interact with the aforementioned stalled frontal zone, bringing the potential for storms Friday afternoon and into Saturday. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... As of 750 PM EDT Saturday... 24 Hour TAF period: A few scattered showers around this evening but the main shortwave causing a more intense shield of precipitation is diving south of the area. Expect most of the remaining shower activity this evening to be concentrated in the eastern half of the area although an isolated shower anywhere cannot be ruled out. Ceilings at this time have all returned to VFR and for the most part, wind gusts have begun to subside. Expect winds out of the west or northwest overnight at 5-10 kts. For Sunday, VFR conditions should prevail with skies clearing and winds out of the west at 10 kts. Long Term: Weather should remain quiet until Tuesday when a shortwave in the upper flow approaches from the northwest and could bring some precipitation to the area. This will begin a train of weak disturbances that may keep weather unsettled through the end of next week. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield/Vincent SHORT TERM...Vincent LONG TERM...CBL AVIATION...Ellis
Area Forecast Discussion...UPDATED
National Weather Service Reno NV
647 PM PDT Sat May 6 2017 .UPDATE... Based on continued accumulations of snow around Tahoe will expand winter weather advisory northward to include that region. Snow levels have been more problematic than normal today, ranging from 6000 to 8000 feet. Example - South Lake Tahoe picking up snow accumulations while Donner Pass has been mainly just wet. Travel impacts could increase after sundown when temperatures cool, even if precipitation rates/coverage decrease per radar and HRRR trends. Only a few inches expected but it`s late season so travelers are less prepared. Rest of forecast and WWA`s unchanged for the time being. So far river and stream responses have not been overly impressive, but will wait to see how precipitation evolves next 1-2 hours before a go/no-go decision on continuing flood watch. -Chris && .PREVIOUS DISCUSSION... /Issued 242 PM PDT Sat May 6 2017/ SYNOPSIS... Moderate to heavy rain and high elevation snow will continue tonight through Sunday. There is potential for minor flooding of creeks and streams with the rainfall this afternoon and evening. Rises on mainstem rivers are also expected. SHORT TERM... Low pressure moving through CA/NV tonight will bring moderate to heavy rainfall to the region, with high elevation snow mainly above 7500 feet. Precipitation continues to develop this afternoon across the Sierra and western Nevada, as we get good diffluence aloft, broadscale lift and low level convergence in association with the deformation zone as the upper low passes to our south. Models have been in good agreement since yesterday showing this deformation precip since yesterday, so forecaster confidence is high for the banded moderate to heavy precip. Precip will continue through the evening and into early Sunday morning, with rainfall totals around 0.50-1.0". A few localized areas could see precip amounts of greater than one inch. CAPE values are rather weak today, but a few embedded thunderstorms may be possible in the main precip that could intensify precipitation amounts as well. There are flooding concerns for the region, mainly for smaller creeks and streams, but there are a few concerns for mainstem rivers as well. Please see our hydrology section below for more details on flood potential. Snow levels are currently over 8000 feet and expected to come down to near 7000 feet after midnight. This will bring several inches of heavy wet snow (3 to 8 inches) for the high Sierra tonight through Sunday morning, with snow impacts likely for the higher Sierra Passes including Mount Rose Summit, Carson, Echo, Deadman, Devils Gate and Sherwin Summits. There could be some areas that receive up to a foot of snow or more, but those elevations will be mainly over 8500 feet. Several inches of snow are likely for the Mammoth Lakes area tonight and Sunday morning as well. Winter Weather Advisory has been issued for Mono-Eastern Alpine Counties for snow above 7500 feet. The cutoff low will move east across southern CA and NV Sunday night with another band of deformation zone precip Sunday night into Monday. There could be some continuing precipitation in Mono- Mineral Counties through this time, but the heaviest precipitation looks to remain south and east of our area. Hoon LONG TERM...Monday and beyond... While the main upper low is expected to continue moving away from the Sierra, a lingering band of wrap around moisture could still bring showers and a few thunderstorms to areas south of US-50 Monday. Coverage and projected precip amounts will be much lower compared to this weekend`s event. For Tuesday, the main low will move slowly east across Arizona with the outermost moisture band possibly producing a few very light showers in southern Mono-Mineral counties. Otherwise, drier and warmer conditions will prevail with ridge axis building into northern CA. By Wednesday, ridge axis builds into the Sierra and western NV. With a few more degrees of warming and weak flow aloft over the Sierra, afternoon cumulus are probable. Farther north, additional cumulus could develop in the Lassen convergence zone, but limited forcing and warmer mid level temperatures arc likely to cap convective development in both of these areas. Later next week, medium range guidance is in reasonable agreement with a strong low pressure approaching the Pacific Northwest coast Thursday, then moving inland across Washington by early next weekend. The main effects will be a notable increase in winds Thursday with breezy conditions continuing Friday and Saturday. Temperatures are also likely to cook back to a few degrees below average by Saturday. As for precipitation chances, the main moisture feed and dynamics of the low are projected to remain north of the Oregon border so significant rain or snow is unlikely. Shortwave energy rotating around the base of the trough could trigger a few light showers at times from Thursday through Saturday in portions of northeast CA and northwest NV mainly north of I-80. Looking ahead to mid-May, it appears that the main trough axis will remain near the west coast with reinforcing shortwaves potentially bringing additional precipitation chances, along with continued below average temperatures. MJD AVIATION... The main weather concern through early Sunday will be periods of rain and higher elevation snow over the Sierra and much of western NV. The peak rainfall intensity is expected between 22z-06z for areas near and north of US-50 (including KTVL-KTRK-KRNO-KCXP). MVFR conditions with widespread mountain obscurations are likely, with brief IFR visibility possible in heavier rain areas. Farther south for Mineral and Mono Counties (including KMMH), another area of widespread rain and mountain snow is expected to develop later this evening and continue into early Sunday, with peak intensity between 06-12Z. While we are not anticipating snow accumulations at KMMH, periods of brief rain-snow mix are possible during heavier precip bursts. Wind gusts up to 30 KT are also possible at times around the region through this evening. There remains a low potential for isolated thunderstorms until 00z for the Tahoe and Reno-Carson terminals until 00Z, but the better potential shifts to west central NV near and east of US-95, where a few cells could linger until 03Z. For Sunday, the better shower potential will shift to areas south of US-50 and east of US-95. Overall intensity and coverage are expected to be less compared to today, with brief MVFR conditions possible. MJD HYDROLOGY... Rivers, creeks, and streams are already running pretty high from the recent warm temperatures and snowmelt, so this additional precipitation tonight will only add to the problems of minor flooding around the region. A areal flood watch remains in effect for the Eastern Sierra and western Nevada, including around the Tahoe Basin. The areas of highest concern will be the creeks and streams around the Tahoe Basin and Carson Range west of Reno- Carson City where flows are already running high and fast. We have issued a Flood Advisory for the East and West Forks of the Carson River as well, as minor flooding is already occurring from snowmelt and irrigation, and additional rainfall will only exacerbate the situation. Rises on the Truckee and Walker Rivers are expected as well, although no major flooding is expected. Truckee River at Truckee will be at minor flood stage through Sunday, with minimal impacts according to the emergency management there. The Truckee River at Vista is expected to rise sharply overnight due to runoff from rainfall. We do not expect to reach flood stage, but it will be very close. Lastly, terminal lakes such as Swan, Silver, Washoe, and White Lakes will likely see an increase of inflow over the next 24 hours from rainfall and snowmelt. Hoon && .REV Watches/Warnings/Advisories... NV...Flood Watch until 5 AM PDT Sunday NVZ002-003. Lake Wind Advisory until 9 PM PDT this evening for Pyramid Lake in NVZ004. CA...Flood Watch until 5 AM PDT Sunday CAZ071>073. Winter Weather Advisory until 11 AM PDT Sunday above 7500 feet in CAZ073. && $$ For more information from the National Weather Service visit...
Area Forecast Discussion
National Weather Service Blacksburg VA
944 PM EDT Sat May 6 2017 .SYNOPSIS... A large upper level area of low pressure will drift slowly northeast along the Appalachians through tonight. This system should finally exit on Sunday followed by weak high pressure that will gradually build in from the west by Sunday night. This area of high pressure will then cover most of the Mid Atlantic region Monday and Tuesday keeping dry and cool weather in place. && .NEAR TERM /THROUGH SUNDAY/... As of 945 PM EDT Saturday... Showers and even a few thunderstorms have continued in southeast WV and small part of Virginia ahead of upper level disturbances rotating around an upper low across northern WV and southwest PA. The 00Z RNK soundings indicated freezing levels around 3200 ft MSL which is contributing to the thunder despite shallow cloud tops. The 00Z HRRR has performed well on the location of precipitation this evening, and continue to expect an decreasing trend in coverage tonight with skies clearing east of the mountains after midnight. Otherwise, dropped temps a couple of degrees based on current observations, but with 5-10kt winds expected, do not expect a significant drop from current levels. Threat of upslope showers diminishes around midday Sunday as vort axis shifts northeast to the Shenandoah Valley to eastern NC. Anticipate plenty of sunshine across the region by Sunday afternoon, after clouds in the morning over southeast WV to the Blue Ridge of VA erode/lift northeast. Still looking at a gradient in the pressure fields between 994 mb low over Quebec and weak high over the mid-MS Valley. Temps tomorrow at or just above today`s highs in the east, and warmer in the west with sunshine returning and 8h temps warming. Look for readings from the mid to upper 50s west, to lower to mid 60s east. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY NIGHT/... As of 225 PM EDT Saturday... Our weather pattern will still be under the influence of the trough axis of a slow moving, cold upper low that will be making progression eastward through New England. Closer to the surface, high pressure will nose its way way into the area Sunday night into Monday. The result will be dry weather with limited cloud cover. Winds will still be a bit gusty given the pressure gradient between the departing low and the approaching high. While the upper low makes its slow progression eastward, an upper ridge of high pressure will build into the Central Plains states. The result will be the development of a NW-SE oriented baroclinic zone that develops from the Upper Mississippi River valley into the central Appalachians by Monday night into Tuesday. A elongated nose of vorticity is expected to extend the length of this feature with showers becoming more common across the area, spreading from southwest to northeast. Prior to the arrival of the associated precipitation and increased cloud cover, some frost is possible late Monday night into early Tuesday morning across parts of far eastern Greenbrier County WV and Bath County VA. During the afternoon Tuesday, there may be enough instability from the development of isolated thunderstorms across the far southwestern sections of the region. Temperatures during this portion of the forecast will average ten degrees below normal. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... As of 250 PM EDT Saturday... Wednesday through the start of next weekend will be an active weather period for showers and some storms. The New England closed low is progged to either retrograde to near Hudson Bay, or split into to distinct lows with one remaining near New England and its counterpart retrograding to the Hudson Bay region. Either solution is accompanied by a breakdown of the central U.S. upper ridge to more of a zonal flow with a developing low in the lee of the Central Rockies ejecting into the mid-Mississippi Valley by the end of the week. This scenario is progged to result in the baroclinic zone across the area making gradual progression north through the region. Also, shower coverage is expected to become greater with better chances of moderate or heavier rainfall as pieces of energy eject eastward from the closed low along this feature heading into next weekend. Temperatures during this portion of the forecast will average five degree above normal. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... As of 750 PM EDT Saturday... The cold pool of air aloft associated with a large closed low over the northeast US is keeping steep lapse rates over the region. This combined with diurnal heating and short wave energy rotating around the upper low has generated some scattered showers and a few isolated thunderstorms across the region, though the radar is trending down as we are past peak heating. Expect the trend for decreasing precipitation will continue and expect TAf sites to be free of any lingering precipitation by 03Z to 06Z. Cigs are expected to remain VFR east of the Ridge, while conditions to the west will trend down to MVFR as orographic forcing combines with low level moisture to generate lower clouds. Any sub VFR conditions will dissipate shortly after daybreak and expect VFR conditions all sites for the latter portion of the valid period as the upper trof slowly starts to move eastward. Expect a bloom of Cu mainly north and east as diurnal heating is once again able to bubble up some clouds, but do not see enough support to generate any precipitation of sub VFR conditions. Winds will be a bit gusty early tonight before stratifying overnight. However, increasing low level flow coupled with diurnal mixing will bring gusty conditions back to TAF sites by late Sunday morning with gusts up to 25kts possible. Extended Aviation Discussion... VFR conditions will persist into Monday. Moisture increases ahead of the next front Tue-Thu so looking at rain chances increasing along with sub-VFR conditions, especially west of the Blue Ridge. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...AMS/WP NEAR TERM...PH/WP SHORT TERM...DS LONG TERM...DS AVIATION...MBS/WP
Area Forecast Discussion
National Weather Service Sacramento CA
321 PM PDT Sat May 6 2017 .SYNOPSIS... Cooler with a chance of mountain showers and thunderstorms this weekend. Gusty north winds Sunday. Turning warm again early next week. && DISCUSSION (Today through Tuesday)... Upper low will be dropping SEwd along the central CA coast today and into SOCAL tonight and Sun. Given the steering flow will be turning from meridional to cyclonic over Norcal tonight and Sun, the precip chances will trend Wly, from the Sierra today, and into the Sierra Foothills and possibly portions of the Ern Central Valley tonight. The last several runs of the HRRR Model REF prog shows the precip trending Wwd over Norcal (from the "backdoor") and towards the I-5 corridor between 8-10 pm Sat. This higher resolution model seems to be capturing the short waves/impulses that are forecast to rotate Wwd this evening to the N of the closed low. The forecast REFs weaken as they move into the Valley and given the forecast soundings indicate a mid level cap, would expect showers but no thunder in the Valley, and have confined mention of thunder to the Foothills. Radar shows echoes generally expanding in areal coverage from early this morning as moisture wraps around the low center. Although we can`t rule out thunder entirely due to the forecast short waves/ impulses that are forecast to move over the area this evening, deep or significant instability looks to be lacking for widespread storms. Dual Pol radar data indicates the snow level is generally at/above 7000 ft with WBZs forecast to lower to around 6500 ft along the I-80 corridor and 5000-5500 ft in Wrn Plumas Co later tonight and Sun morning. Sierra peaks along and south of I-80 are forecast to receive up to about 4 inches or so of snow through tonight. Little impacts expected for the 80/50 corridor. Building surface high pressure system off the coast will increase the pressure gradient across the valley and the northern mountains starting this afternoon into Sunday. This will bring breezy winds for the northern Sacramento Valley today with gusty winds for most of the valley Sunday. Forecast pressure gradients increase from 10 mbs to 13-14 mbs this evening and overnite which should push winds to near/above WAD criteria mainly on the W side of the Valley and lee-side of the coastal range. Gradients and 925 mbs wind support decreases rapidly Sun afternoon. Would expect winds to decouple enough in the Valley tonight but increase to WAD levels late this evening for the lee-side of the coastal range as the Nly barrier jet develops on the W side of the Valley and surrounding foothills. Thus, the two distinct beginning times for the WAD. As the upper level ridge builds from the west on Sunday, dry conditions will return for the forecast area with high temperatures will warm to slightly above normal for Sunday and between 5 and 10 degrees above normal for Monday/Tuesday. Increasing anticyclonic flow will account for adiabatic warming and should shunt precip chances mainly well to the S of our CWA, save for the are just N of Yosemite NP. JHM .EXTENDED DISCUSSION (Wednesday THROUGH Saturday) High confidence in cooler and breezier conditions returning for interior NorCal after mid-week as upper ridge breaks down and shifts east as another trough sets up near the West Coast. Shower chances expected to be confined to mainly the mountains late next week. JClapp && .AVIATION... VFR conditions expected next 24 hours except local MVFR/IFR vicinity scattered showers and isolated thunderstorms over the northern Sierra Nevada 20Z-06Z this weekend. Northerly surface wind gusts 15-25 kts continuing northern Sac Valley overnight, especially between 1-2K MSL. Northerly winds developing for remainder of Sac Valley overnight, especially westward of Hwy 99. JClapp && .STO WATCHES/WARNINGS/ADVISORIES... Wind Advisory from 11 PM to 4 PM PDT Sunday for Clear Lake/ Southern Lake County-Mountains Southwestern Shasta County to Northern Lake County. Wind Advisory from 8 AM to 4 PM PDT Sunday for Central Sacramento Valley-Northern Sacramento Valley. && $$
Area Forecast Discussion
National Weather Service Las Vegas NV
750 PM PDT Sat May 6 2017 .SYNOPSIS...A low pressure system will be impacting the region through the weekend bringing cooler temperatures and breezy to gusty winds along with showers, thunderstorm chances, and mountain snow. && .UPDATE...So far this afternoon and early evening, showers and thunderstorms have been rather isolated across mainly Inyo, San Bernardino, and Nye Counties. As the upper low which is currently just off the southern CA coast shifts east this evening we are still expecting a band of showers and isolated thunderstorms to develop out ahead of the low. Current radar is showing this band starting to take shape across far eastern San Bernardino County. The HRRR and other hires models do continue to indicate showers developing in this area and rotating north and west between 9pm and midnight. How far east this rain band makes it is still in question and right now the best area for seeing rain will be over eastern San Bernardino, western Clark, southern Nye, and Inyo Counties. It`s still possible that Las Vegas may see some measurable rainfall, but its more likely west of town. After midnight the models indicate a pretty good dry slot moving into the area from the south which is expected the bring an end to much of the shower activity. However, we should see moisture fill back in on Sunday along with a little more instability as the upper low moves over San Bernardino County. Will go ahead and let the Wind Advisory and Red Flag Warning expire at 8pm this evening, but will let the Winter Weather Advisory ride into Sunday. && .AVIATION...For McCarran...Southwest winds should persist the rest of tonight and could gust to 25 kts at time until around 06z. Clouds will continue to fill in this evening and lower with showers and cigs around 5 kft possible mainly between 06z and 09z. Showers Sunday will mainly be over the mountains with clouds at LAS sct-bkn about 10 kft. Winds Sunday will favor a southeasterly direction 8-15 kts. For the rest of southern Nevada, northwest Arizona and southeast California...Southerly flow will dominate through the weekend and through the beginning of next week. Breezy southeast to southwest winds of 15-30 with gusts up to 40 kts winds will persist through this afternoon and diminish this evening. Scattered chance of rain across our region will cause periods of lower ceilings, but should remain within VFR conditions. Best chance of rain for most TAF sites between 06-12Z this evening, slight chances of rain continuing through tomorrow afternoon for BIH and DAG. Gusty winds will begin to diminish around 02-03Z tonight across the region, lingering longer at DAG. Less gusty winds tomorrow with sustained winds 8-15 kts with occasional gusts up to 22 kts in the afternoon. For the rest of southern Nevada, northwest Arizona and southeast California...Southerly flow will dominate through the weekend and through the beginning of next week. Breezy southeast to southwest winds of 15-30 with gusts up to 40 kts winds will persist through this afternoon and diminish this evening. Scattered chance of rain across our region will cause periods of lower ceilings, but should remain within VFR conditions. Best chance of rain for most TAF sites between 06-12Z this evening, slight chances of rain continuing through tomorrow afternoon for BIH and DAG. Gusty winds will begin to diminish around 02-03Z tonight across the region, lingering longer at DAG. Less gusty winds tomorrow with sustained winds 8-15 kts with occasional gusts up to 22 kts in the afternoon. && PREV DISCUSSION 212 PM PDT Sat May 6 2017 .SHORT TERM...Through Monday Morning. Gusty winds have developed basically as expected this afternoon, if not slightly stronger than forecast across the Las Vegas Valley. The Wind Advisory and Red Flag Warning currently in place look good and will continue through 8pm this evening. As of 2 PM this afternoon, showers and thunderstorms were just beginning to develop across the NNSS and the southern Sierra, slightly behind the timeframe expected earlier this morning. In any case, additional development is expected across southern Nevada and Inyo County tonight, mainly to the north and west of Las Vegas. Then after sunset, rapid development is expected across eastern San Bernardino and southern Mohave County (including the Colorado River Valley). This area will expand north overnight, likely spreading across the Las Vegas Valley between 10pm and 4am. This slug of activity is expected to wrap west across the Sierra Sunday morning before diminishing Sunday afternoon. Models are still holding on to the idea of a dry slot making its way across the middle of the forecast area during the day Sunday, with showers lingering around the periphery. The main threats with any storms through this period will be gusty winds, lightning, hail, and brief heavy rain/snow. Speaking of snow, a Winter Weather Advisory was issued earlier today for the Spring Mountains today into Sunday morning, and for the Sierra and White Mountains for today through Monday afternoon. This decision was made based on the recent warm spell and the likelihood of outdoor enthusiasts enjoying the mountain wilderness this weekend. They may be caught off-guard by sudden winter weather conditions such as heavy snow in addition to lightning, hail, and gusty winds. Snow levels will drop from around 10000 feet today to 7000-8000 feet overnight. Snow totals will be highly variable, but in general a trace to 8 inches is likely, with higher amounts possible near the Sierra crest. .LONG TERM...Monday through Friday. The cutoff low and its assortment of weather will be the main focus for the first half of this period. Models are tightly clustered, and also agree well with previous runs, so confidence in the large scale pattern is above average, but confidence in details such as precip placement and point temperatures is below average. On Monday, the low has dived well south of the area, with models indicating a significant dry slot over most of our CWA between higher precip chances near the low center and also in a SW-NE oriented band from the Sierra through the Great Basin. Tuesday, as the low tracks northeast across Arizona, models suggest the northern band will fall apart and precip chances will consolidate in the western semicircle of the low. Raised PoPs for our eastern zones, particularly Mohave County, for this period. As the low pulls away to the east Wednesday, precip chances will decrease from west to east, with dry weather expected areawide from Wednesday night through Friday. Temperatures are expected to increase overall from the abnormally chilly day on Sunday, but as noted earlier, confidence in point temperatures is low because of dependence on exact placement of cloud cover and precip/virga. As the area dries out and skies clear up Thursday and Friday, temps should return to near normal. && .FIRE WEATHER...Gusty winds will continue into this evening across much of the region. Low relative humidity along with the gusty winds have led to critical fire weather for northwest Arizona and the Colorado River Valley, where Red Flag Warnings are in effect. Expect calmer, cooler, and more moist conditions as the low pressure system lingers over the region into early next week. && .SPOTTER INFORMATION STATEMENT...An area of low pressure will impact the region through the weekend, bringing showers, thunderstorms, and gusty winds. Spotters are encouraged to report any impacts from the wind, such as damage or blowing dust/visibility restrictions as well as rain amounts according to standard operating procedures. && $$ UPDATE...Gorelow SHORT TERM...Wolcott LONG TERM....Morgan AVIATION.....Harrison/Kryston For more forecast information...see us on our webpage: or follow us on Facebook and Twitter