Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 10/05/21

Area Forecast Discussion
National Weather Service Boston/Norton MA
1052 PM EDT Mon Oct 4 2021 .SYNOPSIS... Weak low pressure will travel eastward along a front that remains stalled south of the south coast overnight. The result will be rain, with isolated thunderstorms possible along the southern coastal waters. High pressure settling over New England on Wednesday brings clearing skies and milder than normal temperatures through Friday. A backdoor cool front ushers in a shot of cooler autumn-like temperatures and onshore breezes later Friday into Saturday. Next chance for rain is around Sunday or Monday. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... 1045 PM update: Weak low pressure is traveling along a stalled front south of the south coast of New England. Scattered thunderstorms formed during the past two hours along the CT coast and over Long Island Sound. Those dissipated but others were forming just south of Long Island. The HRRR and other models show an uptick in convective activity for the coastal areas off of RI and MA over the next few hours. Have used CAPE greater than 120 as the delineator for where to include a slight chance of thunder for the overnight hours... which restricts it to southern RI and southeast MA, including the Islands. Otherwise, easterly flow and periods of rain will continue overnight. Hydrologically, river gages are again showing rises as the second round of rains have resumed, but the rate of rise is fortunately fairly gradual. While there could be some areas of minor flooding in urban and poor drainage settings, rises on all rivers are expected to be of the within-bank variety. Lows only drop about 5 degrees or so tonight given clouds and onshore flow, mainly from some upper 40s across NW MA to 50s/near 60 elsewhere. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... Updated 1 PM Mon: Slow improvement Tuesday as low pressure exits region. Cross sections show plenty of leftover moisture beneath inversion so expecting cloudy day, perhaps a leftover shower across eastern MA in morning. Flow becomes more N/NE which will begin to send drier air our way, but any appreciable clearing should hold off until Tuesday night or early Wednesday morning. This pattern keeps us in small diurnal temperature ranges, with 50s and 60s for highs Tue and lows in 40s/50s Tuesday night. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Highlights: * Milder than normal and dry weather mid to late week. * Backdoor front moves across New England later Friday, bringing a shot of slightly cooler than normal temps and onshore breezes for later Friday into Saturday. * More unsettled weather around Sunday or Monday but not a slam dunk. Details: Large high pressure to build/settle over New England Wed thru Fri, bringing a lengthy period of dry weather and strong diurnal range in high and low temps. Highs in the upper 60s to mid 70s and lows in the upper 40s to mid 50s should be fairly common. Coming out of a wet weather regime and with good radiational cooling each night, do have to watch for patchy radiational fog during the late night/overnight. Later Fri night into Sat, a potent shortwave digging SE into the Canadian Maritimes will ridge southward a 1030 mb high pressure. It will also be accompanied by sharply falling 925-850 mb temps into the mid single digits Celsius range! This will also bring about a freshening/strengthening of NE/ENE onshore flow, which could be strong enough for a period of marine headlines in terms of gusts. Carried a slight chance for showers but should be mainly dry for this period. Temperatures should trend more seasonable or slightly below average (highs in the 60s/lows in the 40s to mid 50s), and the onshore breezes will also make it feel on the cooler side to begin the holiday weekend. Though it is something of a roller-coaster in terms of temperatures, it is all-in-all a dry weather period. Indications are that the next chance for more widespread rain showers around Sunday or Monday, but this isn`t set in stone as yet. Will continue to carry slight to lower chance PoP reflected in the NBM. Temperatures look to be more seasonable if slightly milder than normal for the second half of the holiday weekend. && .AVIATION /03Z TUESDAY THROUGH SATURDAY/... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 03z TAF Update: Moderate confidence. MVFR and IFR throughout the region, trending toward IFR/areas LIFR overnight. Areas of rain/drizzle/fog. Isolated thunder possible, mainly in eastern CT, RI, and southeast MA. Slow improvement Tue to MVFR ceilings as rain departs in the morning and probably VFR ceilings Tue afternoon in western MA/CT before remaining areas show improvement Tue night. E/NE flow through tonight and more of N/NE flow Tue/Tue night. KBOS Terminal...Moderate confidence in TAF. Onset of IFR is uncertain and could be off by +/- 2 hours. KBDL Terminal...High confidence in TAF. Outlook /Wednesday through Saturday/... Wednesday through Friday Night: VFR. Saturday: Mainly MVFR, with areas VFR possible. Breezy. Slight chance RA. && .MARINE... Forecaster Confidence Levels. Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 1045 PM update... High confidence through Tue night. Stalled front near South Coast will maintain E/NE flow through tonight with 20-25kt gusts at times, especially near Cape Cod and islands with 4-6 ft seas farther offshore. Keeping SCAs posted for these areas. Boston Buoy was still reporting 5 ft seas late this evening, so will continue SCA for Ipswich Bay, instead of allowing it to expire. Low pressure will pass south of New England tonight, so periods of rain and fog overnight. Isolated thunderstorms possible, mainly over southern RI and southeast MA. Winds back to N/NE Tue and Tue night as low passes offshore. Outlook /Wednesday through Saturday/... Wednesday: Winds less than 25 kt. Seas locally approaching 5 ft. Wednesday Night through Friday: Winds less than 25 kt. Friday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Saturday: Winds less than 25 kt. Seas up to 5 ft. Slight chance of rain. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory until 7 AM EDT Tuesday for ANZ232>235-237. Small Craft Advisory until 8 PM EDT Tuesday for ANZ250-251- 254>256. && $$ SYNOPSIS...Loconto/JWD/GAF NEAR TERM...Loconto/JWD/GAF SHORT TERM...JWD LONG TERM...Loconto AVIATION...Loconto/JWD/GAF MARINE...Loconto/JWD/GAF
Area Forecast Discussion
National Weather Service Charleston SC
1018 PM EDT Mon Oct 4 2021 .SYNOPSIS... A weak coastal trough will approach the area late tonight, before moving onshore Tuesday. A complex storm system will then bring periods of unsettled weather mid to late week. High pressure will build inland later in the weekend. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... Late this evening, KCLX detected a few clusters of showers across inland GA, with weakening showers over inland SC. Shower activity should continue to decrease through the rest of the evening. Latest run of the HRRR indicates that showers will begin to develop over the marine zones during the pre-dawn hours as a coastal trough drift westward. The forecast appears on track. The forecast update will feature small changes to PoPs, sky, and temperatures. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/... A large mid level low will linger over the Lower Mississippi River Valley Tuesday into Wednesday, before slowly lifting northward on Thursday. This set-up will maintain a deep moisture feed over the area with PWats nearing or exceeding 1.75 inches at times. The surface pattern will largely be characterized by high pressure to the northeast and an inverted trough meandering over the region. This time period looks fairly unsettled with higher than normal rain chances. Scattered to numerous showers, with a few thunderstorms, are expected each day. Coverage will be maximized during the daytime when instability is highest, but activity could persist overnight as well. High temperatures will mainly be in the lower to mid 80s. Lows overnight will be ~5 degrees above normal, ranging from the upper 60s inland to around 70/low 70s at the immediate coast. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... A mid level trough axis will shift towards the East Coast Friday into Saturday. At the surface, a coastal trough or perhaps a weak low will meander off the Southeast coast, while high pressure resides inland. NHC continues to keep a very low probability of tropical development with this feature. The pattern favors at least scattered showers with isolated thunderstorms each day. By Sunday, a ridge extending northward from the Gulf of Mexico will edge eastward and could push the deepest moisture off the coast. Maintained rain chances in the forecast, but there should be less coverage than previous days. Temperatures will be within a few degrees of climatology. && .AVIATION /02Z TUESDAY THROUGH SATURDAY/... Convection is expected to remain well inland of the terminals this evening. TAFs will feature VFR conditions with steady SE winds through tonight. During the daylight hours on Tuesday, a coastal trough is expected to push inland, passing over the terminals during the mid-day. Showers and thunderstorms may develop and remain somewhat concentrated within the sfc trough. The TAFs will feature a TEMPO between 16-10Z for showers, thunderstorms are possible. Extended Aviation Outlook: Flight restrictions possible, mainly in showers, mid to late week. && .MARINE... Tonight: Southeasterly flow will prevail across the local waters with speeds topping out in the 10-15 knot range. Seas are expected to average 2-3 feet. Tuesday through Saturday: East to southeast winds will persist through mid week with speeds 15 knots or less. Seas will average 2- 4 feet. Winds will turn to the northeast late week into the weekend as a coastal trough or perhaps weak low meanders off the Southeast coast. Conditions are expected to remain below Small Craft Advisory criteria. && .TIDES/COASTAL FLOODING... The evening high tide will occur around 715 pm in Charleston Harbor. Currently, tidal departures are running at about 0.5 ft and a local tide forecast tool expects the evening high tide to peak around 6.8-6.9 ft MLLW. Therefore, a Coastal Flood Advisory is not anticipated at this time. Due to the upcoming new moon (10/6) and perigee (10/8) astronomical tide levels will steadily increase this week. Onshore winds could drive tidal departures up enough to produce minor coastal flooding beginning Tuesday evening in/around Charleston. The time period of primary concern will come late in the week when the astronomical tide peak coincides with northeasterly winds. This could produce moderate coastal flooding in and around the Charleston area. Although chances are slightly less, minor coastal flooding at Fort Pulaski is also possible, mainly near the end of the week. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...NED SHORT TERM...ETM LONG TERM...ETM AVIATION...NED MARINE...BSH/ETM TIDES/COASTAL FLOODING...
Area Forecast Discussion
National Weather Service Corpus Christi TX
612 PM CDT Mon Oct 4 2021 .AVIATION... CIGs are at VFR levels and VFR conditions will persist tonight through Tuesday as skies clear behind a dry frontal boundary. A few storms that were across the Brush Country and Rio Grande Plains this afternoon, have exited the area to the south and west. Can not rule out a few sprinkles across LRD over the next couple of hours before clearing out. Light north to northeast winds can be expected with the direction being variable at times. && .PREV DISCUSSION... /Issued 400 PM CDT Mon Oct 4 2021/ SHORT TERM (Tonight through Tuesday Night)... An upper level trough, extending from TX to the lower Mississippi Valley, is predicted by the ECMWF/GFS/NAM to transition to a cut- off low late tonight/Tuesday, with the center meandering over the ARLATEX region. The associated synoptic scale descent/700-300mb Q-vector divergence expected over the CWA during the period. The surface reflection of the upper system, a weak frontal boundary, triggered isolated convection this afternoon, mainly over the western half of the CWA. Expect this convection to continue then dissipate by 03z Tuesday, based on predicted GFS/HiResW surface theta-E values (caveat, the RAP suggests that drying will be slower). Concur with the NAM/GFS with regard to PWAT values below 1 inch later tonight/Tuesday. Owing to significantly drier conditions tonight, expect cooler temperatures tonight with lows generally 60-65F, and maximum temperatures mid 80s to the lower 90s Tuesday, similar to the SREF ensemble mean values. LONG TERM (Wednesday through Monday)... The long term period is expected to be quiet and pleasant. High pressure is expected to build over South Texas at the beginning of the long term and remained park over the area through the weekend. Towards the beginning of next week, the surface high pressure is expected to move eastward as an upper level low with associated cold front moves into North Texas which will begin to erode the upper level ridge. With limited moisture across South Texas, mostly sunny to clear skies can be expected throughout the long term. Max temperatures are expected to remain constant ranging within the lower to mid 90s while lows drop into the 60s inland and lower 70s near the coast. With the drier air in place, heat indices are expected to remain under 100 degrees until late this weekend when moisture returns to the area. MARINE... Isolated showers/thunderstorms may occur this evening/early tonight along a weak boundary. Otherwise, drier conditions tonight/Tuesday. Weak to moderate northerly flow is expected Wednesday with onshore flow returning Thursday. Weak to moderate winds will return this weekend as the high pressure gradually moves eastward. Dry conditions as well as seas under 3 feet are expected throughout the long term. && .PRELIMINARY POINT TEMPS/POPS... Corpus Christi 65 87 65 88 67 / 10 0 0 0 0 Victoria 60 87 61 89 64 / 10 0 0 0 0 Laredo 67 91 66 94 67 / 20 0 0 0 0 Alice 62 92 61 91 62 / 10 0 0 0 0 Rockport 68 87 69 87 71 / 10 0 0 0 0 Cotulla 64 91 65 95 66 / 10 0 0 0 0 Kingsville 63 90 62 90 64 / 10 0 0 0 0 Navy Corpus 72 85 73 85 74 / 10 0 0 0 0 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...None. GM...None. && $$ TE/81...AVIATION
Area Forecast Discussion
National Weather Service Duluth MN
636 PM CDT Mon Oct 4 2021 .DISCUSSION...(This evening through Sunday) Issued at 402 PM CDT Mon Oct 4 2021 Summary: Dense fog is possible across much of the CWA tonight. Dry and warm conditions will dominate for the majority of the week, before a system brings another round of rain for Friday through Saturday. Stratus is lingering in northwest Wisconsin With dewpoints near in the low 50s and temperatures decreasing into the upper 40s once again overnight, there is another possibility for some dense fog across the majority of the Northland. Dense fog is less likely where the stratus is expected to hover over our eastern counties in northwest Wisconsin. A Dense Fog Advisory is in effect tonight from 1 AM to 10 AM Tuesday morning. Patchy fog could linger past the 10 AM expiration. The high pressure system is expected to remain over the upper Midwest, bringing dry conditions and above normal temperatures in the upper 60s and low 70s for the majority of the work week. On Friday, a trough in the Desert Southwest will move northeast over the Rockies and Northern Plains and bring more light rain showers with possible isolated thunderstorms to the Northland for the weekend. A small ridge will give us a break from precipitation on Monday before a second closed upper level low brings more precipitation to our area on Tuesday. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 636 PM CDT Mon Oct 4 2021 VFR conditions are expected for a time this evening before another bout of IFR/LIFR ceilings and visibilities redevelop tonight. Weather conditions will be similar to what they were last night, except the high pressure ridge axis should be more to the east over northwest Wisconsin. Fog and low stratus are most likely for HIB, DLH, and HYR. The RAP model indicates the low stratus deck near HYR this evening will continue to diminish, enhancing radiational cooling, so we have reduced the visibilities there for tonight. Fog and low stratus will eventually diminish around mid-morning Tuesday, but there is some uncertainty as to exactly when these conditions will improve. && .MARINE... Issued at 402 PM CDT Mon Oct 4 2021 A high pressure system over the Northland will bring calm conditions over Lake Superior for the next couple days. Fog is possible each night over the lake, but is expected to clear throughout each morning. Otherwise, light winds and waves below 2 feet wil be present over western Lake Superior over the next 48 hours. && .PRELIMINARY POINT TEMPS/POPS... DLH 49 66 52 70 / 0 0 0 0 INL 47 74 54 75 / 0 0 0 0 BRD 48 73 53 73 / 0 0 0 0 HYR 45 71 48 72 / 0 0 0 0 ASX 44 70 49 74 / 0 0 0 0 && .DLH WATCHES/WARNINGS/ADVISORIES... WI...Dense Fog Advisory from 1 AM to 10 AM CDT Tuesday for WIZ001- 006>008. MN...Dense Fog Advisory from 1 AM to 10 AM CDT Tuesday for MNZ011-012- 018>021-025-026-033>038. LS...None. && $$ DISCUSSION...Kossen AVIATION...JTS MARINE...Kossen
Area Forecast Discussion
National Weather Service Des Moines IA
643 PM CDT Mon Oct 4 2021 ...Updated for the 00z Aviation Discussion... .DISCUSSION.../Tonight through Monday/ Issued at 256 PM CDT Mon Oct 4 2021 Key Message: -Fog tonight and again Wednesday morning -Light rain Wednesday into Thursday -Warmer over the weekend The main forecast concern was focused on the fog tonight into Tuesday morning. Surface high pressure strengthens and moves over the northeast part of the state tonight into Tuesday providing plenty of subsidence. Minimum temperatures look to be near or slightly warmer that this morning lows and dewpoint depressions should be less than 2-3 degrees past 06z Tuesday. The majority of the hires models are in agreement with fog developing, but the location and density remain questionable. Still, leaned toward the latest HRRR and ARW suggesting the densest fog is in the northeast and this is where the dense fog developed this morning. Confident to hoist a Dense Fog Advisory for the northern parts of the forecast area and wouldn`t be surprised if it needed to be expanded. Fog again is possible Wednesday morning with the surface high pressure remaining over the region. Just have mention in the northeast for now with increasing clouds across the west and south due to an approaching low pressure system. Speaking of this upper level low pressure system, it appears to stall over the Ozarks into Thursday night before slowly moving east-northeast by Friday. There`s a slight uptick in the potential for showers and even a stray thunderstorm Wednesday afternoon through Thursday afternoon over the eastern portions of the forecast area. The forcing and moisture remain limited and thus kept chance pops going. Friday into Sunday...good WAA develops by Saturday morning and provides a nice warm up over the weekend. Highs look to be back in the 80s over the weekend for much of the forecast area. The ECMWF and GFS suggest a surface low pressure to pass across the Dakotas into Minnesota Saturday night into Sunday but any precipitation remains to the north as the state gets locked into the dry slot. && .AVIATION.../For the 00Z TAFS through 00Z Tuesday evening/ Issued at 643 PM CDT Mon Oct 4 2021 Will see VFR ceiling affect eastern portions of the forecast area overnight including KALO and KOTM. In addition, locally dense fog is expected on the back edge of any cloudiness, most pronounced in northern Iowa. Therefore, MVFR to IFR visibilities are expected around sunrise on Tuesday across the area. By midday on Tuesday, much of the area should once again see VFR ceilings and visibilities with light northeast surface winds becoming more easterly with time. && .DMX WATCHES/WARNINGS/ADVISORIES... Dense Fog Advisory from 2 AM to 9 AM CDT Tuesday for IAZ005>007- 016-017. && $$ DISCUSSION...Podrazik AVIATION...Cogil
Area Forecast Discussion
National Weather Service Huntsville AL
1058 PM CDT Mon Oct 4 2021 .UPDATE... For 06Z TAFS. && .NEAR TERM...(Tonight) Issued at 905 PM CDT Mon Oct 4 2021 A cold front that moved across the Tennessee Valley from west to east last night, remained east of the region. It extended roughly from far western NC, across NW GA, and south of BHM. An outflow boundary that was generated from previous convection to our SE earlier today, was moving to the NW across the area; it extended roughly from around Aliceville, to Cullman, and west of Scottsboro and Pittsburg. A few showers (with a little thunder earlier) continued along this boundary over parts of Cullman county. Other shower activity continued south of I-20 over eastern AL and western GA, with it moving to the NE at the present. Otherwise rather mild to warm conditions prevailed over the Tennessee Valley, with temperatures ranging in the mid 60s to around 70 with light winds. The on-going forecast trend looks to be reasonable regarding a lowering of rain chances this evening and the first few hours of Tuesday. Rain chances should begin increasing from the SE to NW in the late night and especially on Tuesday, as the frontal boundary returns westward, and deep moisture from the Gulf/Atlantic overspread the region. An upper level low is also forecast to form over the Deep South, helping enhance broad scale lift over the region. The shorter term models were in fair agreement depicting the moisture and high rain chances returning. The HRRR was the slower and drier one, not quite bringing showers over our eastern areas until daybreak Tue. The others were a bit faster; am staying more this trend. Some of the rainfall over the eastern area could become locally heavy, bringing a risk of flooding for our far eastern areas. The Flash Flood Watch (that starts at 1 AM Tue morning) looks valid, with no changes needed. Given that rainfall may be delayed for the more western areas, will add more patchy fog for the overnight. Passing mid/upper clouds should keep it from being as widespread and/or dense as was the case earlier today. .SHORT TERM...(Tuesday through Wednesday) Issued at 248 PM CDT Mon Oct 4 2021 Coverage of precipitation will continue to increase into the day on Tuesday as continued moisture advection pushes PW values up into the 1.6-1.8 inch range. These values are above the 90th percentile for early October PW climatology. Therefore, expect any showers/storms that develop will produce heavy rainfall. Due to this, a Flash Flood Watch starts early Tuesday morning and will continue through late Wednesday night. The lower heights aloft from the upper closed low will lead to decent mid- level lapse rates.Not seeing any signal for the chance for tornadoes or damaging winds with weak low and mid- level flow but there could be some small to marginally severe sized hail on Tuesday afternoon. Also, seeing some decent convection on the latest 12z CAMS for Tuesday afternoon. Overall, think this is a rather small threat but could not rule out a few stronger to marginally severe storms Tuesday afternoon and evening. Expect this threat will end with the loss of daytime heating Tuesday evening. High temperatures on Tuesday will be in the low to mid 70s for most locations. Widespread precipitation will continue into the overnight hours Tuesday night as shortwave troughs continue to rotate around the eastern periphery of the upper level closed low. Models indicate that this low does drift a but to the northwest Tuesday night and into Wednesday. Overnight lows will generally be in the low to mid 60s. The axis of moisture shifts a bit further to the east on Wednesday as drier air begins to wrap around the southern periphery of the closed low. This will lead to better chances for showers/storms across northeast Alabama and southern Middle Tennessee with slightly lower chances and rainfall amounts over northwest Alabama. Once again, could not rule out a strong storm or two during the afternoon with small to marginally severe sized hail being the main threat. PW values will remain elevated, especially over northeast Alabama. High rainfall rates will lead to the possibility of flash flooding again on Wednesday. Rainfall amount on Tuesday-Wednesday will range from 1-3 inches with locally higher amounts possible. Highs on Wednesday will continue to be in the mid to upper 70s. .LONG TERM...(Wednesday night through Sunday) Issued at 248 PM CDT Mon Oct 4 2021 Drier conditions will finally return during the long-term portion of the forecast. The upper level closed low begins to slowly lift out to the north and east late Wednesday and into Thursday. A few showers will linger across the area on Thursday, especially for locations to the east of I-65. Higher heights aloft will build into the region behind the departing closed low. Temperatures will climb into the upper 70s to low 80s on Friday with low to mid 80s for most locations on Saturday. Low temperatures in the long-term will generally range from the upper 50s to mid the mid 60s. Despite the drier pattern, there is no sign of any fall cold front in the long-term forecast. Dewpoints will remain in the upper 50s to mid 60s throughout the period. && .AVIATION...(For the 06Z TAFS through 06Z Tuesday night) Issued at 1058 PM CDT Mon Oct 4 2021 With mainly just some mid/high clouds filtering into the area from the SW in the wake of a frontal passage, VFR conds are expected into the morning hrs Tue. Cigs closer to 3-4K ft will then develop late Tue morning, as an upper disturbance meanders over the lower MS/Mid South regions. Additional shra/tsra are also expected to develop in response to the upper wave, and PROB30 groups have been added to the latter half of the TAF period. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...Flash Flood Watch through late Wednesday night for ALZ001>010-016. TN...Flash Flood Watch through late Wednesday night for TNZ076-096-097. && $$ NEAR TERM...RSB SHORT TERM...MA LONG TERM...MA AVIATION...09 For more information please visit our website at
Area Forecast Discussion
National Weather Service Lincoln IL
831 PM CDT Mon Oct 4 2021 .SYNOPSIS... Issued at 311 PM CDT Mon Oct 4 2021 Scattered showers and isolated thunderstorms are possible each day this week, mainly during the afternoon hours. The best chances for precipitation will be on Wednesday and Thursday. Temperatures stay near average this week, with highs in the 70s. && .UPDATE... Issued at 831 PM CDT Mon Oct 4 2021 0120z/820pm radar imagery continues to show isolated showers along/north of the I-74 corridor. The showers are dropping southwestward and will dissipate over the next couple of hours. Updated the forecast to keep slight chance PoPs going through 04z/11pm followed by cloudy and dry conditions overnight. Low temperatures will drop into the upper 50s and lower 60s. && .SHORT TERM...(This evening through Tuesday) ISSUED AT 311 PM CDT Mon Oct 4 2021 The upper trough extending from the eastern Great Lakes into TX is beginning to cut off over the southern Mississippi Valley Region, and will continue to do so over the upcoming day as a large scale ridge over much of the US amplifies into south central Canada. This will promote a continued warm air mass over the central US, tempered by cloud cover and precipitation associated with the cut- off low. In the mean-time, scattered diurnally driven showers over central IL this afternoon should diminish fairly rapidly after sunset. Some confluence at the north side of the cut-off looks to produce shower activity Tuesday, also fading away near sunset. Expect little air mass change, again resulting in lows around 60 tonight and highs in the mid 70s Tuesday. .LONG TERM...(Tuesday night through Monday) ISSUED AT 311 PM CDT Mon Oct 4 2021 The cut off low from the southern Mississippi Valley Region will eject north-northeastward Wednesday through Friday, crossing over the central IL vicinity. This will bring better chances for rain showers and thunderstorms Wednesday and Thursday, potentially lingering into Friday. A shortwave ridge should bring dry conditions by Saturday, however another frontal system looks to move into the Midwest or upper Midwest Sunday into Monday, and this could bring another period of precipitation. Forecast uncertainty appears high around this time period, however, as highly variable model solutions are noted this late in the forecast. Temperatures should remain slightly above normal midweek into Friday, with highs generally 70s, then warmer temperatures are expected over the weekend, with highs in the 80s, as the cloudier conditions exit and more southerly flow returns. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) Issued at 644 PM CDT Mon Oct 4 2021 Patchy low VFR cloud cover prevails across central Illinois early this evening. Winds are primarily northwesterly at less than 10kt: however, as winds veer to northeasterly, MVFR clouds across the southern Great Lakes will spread/develop into the area tonight. Based on HRRR forecast, it appears MVFR ceilings will develop at KBMI/KCMI at 03-04z...then further southwest to KSPI by around 07z. Forecast soundings suggest a period of IFR is possible toward dawn, particularly at KBMI and KCMI. Once the low clouds arrive, they will likely stick around for quite some time...with perhaps a brief improvement back to low VFR by late Tuesday afternoon. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Barnes SYNOPSIS...37 SHORT TERM...37 LONG TERM...37 AVIATION...Barnes
National Weather Service Jackson KY
840 PM EDT Mon Oct 4 2021 .UPDATE... Issued at 840 PM EDT MON OCT 4 2021 Most of the low level clouds that were across the region this afternoon have dissipated/eroded with a few lingering near the VA border and some mid level clouds across the Bluegrass region. Additionally, some cirrus is passing overhead across mainly the southern half of the area. Dewpoint depressions in valleys are in the 0 to 3 or 4 degree F range across much of the area with light winds prevailing. This following recent precipitation and somewhat moist solids should set the stage for valley fog development by around midnight. This fog should linger most of if not all of the night, with guidance also suggesting some fog in more open terrain and some midslope to ridgetop locations. A limiting factor as far as areal extent and a reason for uncertainty with the evolution of the fog is an expected increase in mid level clouds from the south and perhaps northwest late tonight. For now have trended for more valley fog compared to the previous forecast and brought in patchy fog chances earlier and lowered pops this evening. && .SHORT TERM...(This evening through Tuesday night) Issued at 430 PM EDT MON OCT 4 2021 Aloft, cut off low over the Midsouth will spin in place as heights rise across the Atlantic Seaboard. Eastern Kentucky will be between these features. As such, moisture will be lifted northward from the Gulf of Mexico and steered straight into the Commonwealth towards the end of the period. At the surface, a stalled out cold frontal boundary over eastern Kentucky will drift back to the west as a warm front as a surface low lifts northward from roughly New Orleans to Memphis during the short term. As a result, eastern Kentucky remains in the warm sector of this storm system through the short term. Sensible weather features isold to widely scattered showers currently across the area this afternoon. While thunder has been absent, a rumble or two can not be ruled out. Early trends were misleading as convection initially fired up quite strongly but waned relatively quickly after initiation. At first, best activity was found across the east but transitioned towards the Blue Grass and northwest from there. HRRR suggests a brief enhancement to convection over the next couple of hours, but overall trends should be towards less activity through sunset. Skies at least partially clear through the evening. But with the moisture return clouds will once again reenter the area late tonight, with rain overspreading the area roughly 24 hours from now. Looks like a potential rain shadow across our southeast as southeast winds eat away at some of the moisture through downsloping actions. Just the same, everyone should see at least a little rain sometime over the course of the latter half of the short term. .LONG TERM...(Wednesday through Monday) Issued at 336 PM EDT MON OCT 4 2021 The period will begin active as an upper level low spins across the Lower Mississippi Valley this will send waves northward leading to periods of showers and thunderstorms. Initially however the flow at 1000 to 850 mb will be southeast and will lead to at least some downslope flow, but the PWATs will be on the order of 1 to 1.5 inches (which will be around the 90th percentile for this time of year) which could help overcome the downsloping. The downsloping will be most pronounced on Wednesday before the upper level is expected to push north and east through the end of the week. In the wake of this upper low expect ridging to work back east and provide a break in the active pattern for the weekend. Maybe a few showers Saturday before a dry day on Sunday. There is quite a bit of uncertainty on the next negatively tilted trough that swings out of the Plains into the Midwest by the first part of next week. This uncertainty is showing in the cluster analysis with one indicting the stronger shortwave trough and much less so on the other possible outcomes, but of course this could be a matter of timing differences as well. Given this uncertainty stuck with the slight PoPs presented by the NBM for now, but could be dry if this system ends up being slower given the negative tilt. && .AVIATION...(For the 00Z TAFS through 00Z Tuesday evening) ISSUED AT 835 PM EDT MON OCT 4 2021 Skies have generally become clear to mostly clear across the region although some mid and low clouds lingered near the VA border with some mid clouds across the Bluegrass/I 64 corridor. Some high clouds were moving across the rest of the area. This should lead to the development of some fog toward 4Z, especially in valleys, with some IFR or lower reductions toward 12Z. TAF sites may be affected by MVFR or possibly brief IFR during the 9Z to 13Z timeframe. With this trended a little lower than guidance overall due to the low dewpoint depressions and relative lack of low and mid clouds currently in place. Fog should lift and dissipate through 13Z to 14Z. How low visibilities go is uncertain and will be determined by the increase in cloud cover that is expected late tonight and on Tuesday morning ahead of a developing low pressure system over the deep south. Precipitation should eventually overspread southern portions of the area toward 18Z and after. Winds are expected to be light and variable through the period, generally around or less than 5 KT. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...RAY LONG TERM...DJ AVIATION...JP
Area Forecast Discussion...UPDATED
National Weather Service Portland OR
838 PM PDT Mon Oct 4 2021 Updated Aviation Discussion .SYNOPSIS...A front will bring light rain to much of the area on Tuesday, with some showers to follow on Wednesday. The cool and unsettled pattern will then persist through the weekend, with additional rain chances Friday and Sunday. && .SHORT TERM...THIS EVENING THROUGH WEDNESDAY NIGHT..Water vapor satellite imagery shows a closed upper low diving southeast across the Gulf of Alaska towards the Pacific Northwest. Differential positive vorticity advection (DPVA) ahead of this feature will lead to surface cyclogenesis today and tonight, with the surface low gradually approaching the coast as it moves north-northeast into the Olympic Peninsula around lunchtime tomorrow. As the low passes closest to the coast tomorrow morning, there will be some breezy southerly winds there, with several high-resolution models suggesting a quick burst of gusts to around 45 mph along the southwest Washington coast at some point in the 6AM to noon timeframe. During that period, gusts to 25-30 mph will be possible in the Willamette Valley as well, so it will be a breezy commute for many tomorrow morning. Rain will also spread east from the coast beginning around 4-6AM PDT. Unfortunately, even the high resolution model guidance is in chaotic disarray in its forecast for the arrival time of heaviest precipitation in the Willamette Valley, but the average of the extremes would suggest the bulk of the rain will arrive around noon to 1 PM. While the forecast reflects this supposedly "most likely" scenario, it is important to be aware that some rain could arrive early enough to thwart any outdoor morning plans, especially if the HRRR is correct in its depiction of an earlier rain arrival. The rain should last for much of the day - clearing from the coast to the eastern Willamette Valley between 6 PM and around midnight - but given this is stratiform rain in an area of weak isentropic lift, rainfall totals are looking pretty anemic. For example, at PDX the NBM`s forecast storm total precipitation through Thursday morning is only 0.14", and its chance for wetting rain (i.e., 0.25") is only around 12%. Tomorrow night, the a reinforcing cold front arrives ahead of the secondary surface low. This one is progged to be better aligned with the upper level low and hence coldest temperatures aloft, so some deeper showers will be possible along the coast, where ample boundary layer moisture and warmth (from relatively warm ocean temperatures as the atmosphere cools after sunset) will induce an unstable vertical thermal profile. Some thunder cannot be ruled out from the north Oregon/southwest Washington shoreline into the Coast Range, where NBM and HREF suggest 10-20% thunder probabilities during the Tuesday night into Wednesday evening time period, so have added that to the forecast for those areas. Some isolated to scattered showers should be around in the rest of the area on Wednesday as well, but the thunder chances are looking low away from the coast given surface heating for instability should be weak. Otherwise, it will be a cool upcoming couple of days, with temperatures unlikely to surpass 65F in most locations, along the coast and inland alike, both Tuesday and Wednesday. In fact, NBM suggests only a 27% chance for temperatures to surpass 60 at PDX on Wednesday. -Bumgardner. && .LONG TERM...THURSDAY THROUGH SUNDAY...The upper trough remains in place through Friday, before a shortwave ridge builds in for the first part of the weekend. A shortwave impulse on the back side of the upper low should bring the area another shot at some rain on Friday and Friday night, but things should clear out on Saturday with the entrance of the ridge. If the area can see some sun on Saturday, it will likely be the warmest (or least cool) day in the entire forecast period for the Willamette Valley, with a ~70% chance of exceeding 60F and a ~25% chance for exceeding 65F at PDX according to the NBM. Thereafter, ensemble agreement is quite high in the pattern trend through the remainder of the long-term period. (Granted, model consensus implies model forecast precision, and not necessarily accuracy.) All four cluster solutions on WPC`s cluster analysis tool page suggest some degree of troughing by the end of the period, though there are some discrepancies between solutions on the depth of it - the deepest (which is also composed of the greatest number of ensemble members) having our area under a -21 to -24 decameter 500mb height anomaly and the shallowest having our area under a -9 to -12 decameter anomaly. Should this pattern materialize, it would favor sub-normal temperatures and above-normal precipitation. Depending on how the kinematic and thermodynamic fields align with the trough these ensemble clusters are forecasting will impact our area Sunday into Monday, there may be another chance for thunder over a large portion of the area. But, given the uncertainty in any forecast 7 days out, the addition of thunder will be forgone for now. -Bumgardner && .AVIATION...Southwest flow aloft continues through Tuesday morning ahead of an approaching upper trough. Mid to high level clouds continue to stream into the area resulting in predominately VFR for inland areas. Coastal areas not currently with IFR conditions are expected to slowly deteriorate towards MVFR/IFR through 06Z Tuesday as a front approaches the coast tonight. This front will likely reach the coast around 09Z to 12Z Tuesday bringing rain and will likely maintain a mixture of MVFR/IFR conditions along the coast. The front will continue moving inland and start impacting inland locations around 15Z Tuesday to 18Z Tuesday, bringing light rain and a chance of cigs lowering to MVFR. For detailed regional Pac NW aviation weather information, go online to: KPDX AND APPROACHES...VFR conditions with broken to scattered high clouds. Light northwest winds will likely turn southwest around 12Z Tuesday. MVFR cigs possible with light rain after 15Z Tuesday. /42 && .MARINE...High pressure offshore will continue to weaken tonight as as a low pressure system approaches. Northerly winds will diminish tonight then turn more southerly after midnight. Seas have been slow to subside today but should fall under 10 feet by early Monday evening. Latest models depict a compact low (around 1002 mb) that will likely move northeast through the northern outer waters Tuesday morning. Southerly winds ahead of an associated cold front will quickly increase to around 20 to 30 kts and likely spread across all coastal waters by 5 am. The strongest winds are expected to occur near the low center, mainly in PZZ270 (northern outer waters) where gale force wind gusts to 35 kt will be possible but should be brief as the low moves through rather quickly. If the track of the surface low shifts further east then parts of the inner coastal waters, mainly north of Cascade head, could also see a period of these stronger wind gusts. The low is expected to weaken as it exits the region and moves onshore near the Olympic Peninsula of western Washington. Winds will turn westerly behind the front by Tuesday afternoon and are expected to fall below Small Craft Advisory levels. A weaker low pressure system will move across the coastal waters Wednesday morning. Winds will back to southwesterly and increase somewhat to around 15 to 20 kt early Wed morning. Westerly winds will then transition to become northerly by Wed night with speeds of around 10 to 15 kt likely through Thursday as high pressure builds back in. This will likely be short lived as the longer range models show another front approaching the coastal waters on Friday. Seas are expected to remain in the 7 to 9 feet range at around 10 to 12 seconds through Tuesday night. A northwesterly swell around 10 feet this afternoon is expected to subside to around 6 to 8 ft overnight into Tuesday morning. Seas will likely become choppy, and may once again touch 10 feet, as the low pressure system moves through the northern waters Tuesday morning. Behind the front a westerly swell around 7 ft is expected to gradually increase by Wed morning to around 8 to 10 ft at 10 to 11 seconds. By Thursday morning seas are again expected to subside to around 4 to 6 ft where they will likely stay through Friday. /DH && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory from 3 AM to 2 PM PDT Tuesday for Waters from Cape Shoalwater WA to Cascade Head OR from 10 to 60 nm. Small Craft Advisory from 5 AM to 1 PM PDT Tuesday for Coastal waters from Cape Shoalwater WA to Cascade Head OR out 10 nm. Small Craft Advisory from 2 AM to 11 AM PDT Tuesday for Waters from Cascade Head to Florence OR from 10 to 60 nm. Small Craft Advisory from 4 AM to 9 AM PDT Tuesday for Coastal waters from Cascade Head to Florence OR out 10 nm. && $$
National Weather Service Raleigh NC
930 PM EDT Mon Oct 4 2021 .SYNOPSIS... A north-to-south oriented surface front and a strong upper level low will hold just to our west through mid week, leaving our area in a warm, humid, and unsettled pattern with a southeasterly flow off the Atlantic. This low will lift northward to the Great Lakes late in the week, while surface high pressure centered over the Northeast strengthens and extends southward into North Carolina. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... As of 930 PM Monday... It remains a challenging forecast tonight, given that the models have not done a great job today, necessitating an increased reliance on observational data for this update. Earlier convection has dwindled as expected, with RAP-adjusted mesoanalyses showing a waning CAPE and overtaking CINH with nightfall. The 00z/05 upper air analyses along with satellite imagery show the upper low settling over AR, with falling heights aloft over the Lower Miss Valley region, raising confidence that the low will ease southeastward overnight toward western MS. The wavy mid level southwesterly flow analyzed over the Deep South and Southeast will likely back to more southerly overnight, a result of rising heights off the Southeast coast and a developing MCV over the central/eastern Gulf Coast. The observed 925 mb flow has already backed from this morning to a S and SSE direction, and with observed surface flow very light and varying but mostly from a S or SE direction, the support remains for a favorable low level flow to generate light moist upglide over the far W Piedmont to the west overnight. PWs remain quite high in the W (over 90th percentile at GSO) and a bit less so in the E (near the 75th percentile at MHX, still above normal), but given these profiles it won`t take much to pop off a shower or two in the W overnight. Will keep a low chance pop in the far W, with little to nothing elsewhere, given the loss of CAPE and the absence of any substantial dynamic forcing for ascent. The very low levels are not quite as wet as earlier RAP runs had suggested, and UA analyses that slightly drier air will actually advect in much of tonight from the S and SSE, so this brings even lower confidence in how much fog and stratus will form overnight, especially given the areas of mid level clouds and convective debris high clouds from the SSW, which could limit radiational cooling. Still, we are already seeing dewpoint depressions under 5F over much of the area, and some isolated fog and stratus patches in the far SW CWA, so still expect areas of fog/stratus overnight, especially in areas that saw rain today. Expect lows of 65-70 except lower 60s over western portions of the forecast area. -GIH Earlier discussion from 330 PM: A shortwave diving SE over the ARKLATEX region this morning will will deepen/close off as it moves over the Lower Mississippi Valley. Deep S-SWLY flow between this developing area of low pressure and subtropical ridging over the western Atlantic has advected a plume of high PWATS of 1.5-1.7" into the Carolinas, which ranks in the 90th percentile or 2 sigmas above normal. Diurnal heating within the axis of the deeper moisture in place across the NC Piedmont has led to the development of moderate instability and scattered/numerous storm development. Convection should largely remain along and west of US 1, with only isolated shower or storm possible to the east. Nocturnal cooling and increasing SBCIN will lead to decreasing rain chances by late evening. However, the next wave of upper perturbations moving into the region during the predawn hours could lead to renewed rain chances, especially across the western Piedmont. Overnight lows in the 60s. && .SHORT TERM /TUESDAY AND TUESDAY NIGHT/... As of 330 PM Monday... The closed low over the lower Ms Valley will gyrate ever so slightly north. Meanwhile the subtropical ridge over the western Atlantic will retrograde westward, back into central NC with notable 30 meter height rises overspreading the area. Central NC will have a feed of both GOM and Atlantic moisture into the area, which will keep the moist 1.5-1.7" PWAT axis over the area. At the surface, models are in good agreement that an inverted sfc trough/wedge front/TMB will briefly develop over the area by the afternoon before surface high pressure begins to wedge south into the area Tuesday night. Fueled by upper impulses moving through the region that largely look to be more concentrated/focus across western NC, still expect the highest PoPs over the western Piedmont. However, the aforementioned feed of Atlantic moisture into central feed coupled with an also inland moving sfc boundary, will likely result in at least some isolated to widely scattered convection over the Sandhills and coastal plain. Continued weak shear and moist lapse rates aloft will preclude a severe threat. Expect the NW-SE temperatures gradient to be a little more pronounced than today, ranging from mid 70s NW to mid 80s SE. Convection will wane after sunset, with some lingering isolated/widely scattered convection possible, mainly across the western Piedmont. The onset of the very shallow NELY winds at the surface will not bring much in the way of an airmass change. Lows in the mid to upper 60s. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... As of 325 PM Monday... Central NC will remain under the influence of the mid/upper level low, centered near AR, and a mid/upper level ridge axis extending from the NC coast up in to the Great Lakes region through the medium range. This will lead to an unsettled weather pattern through the remainder of the work week. Wednesday through Friday: Over the past couple runs of model guidance, the timing of the heaviest rainfall for central NC has been pushed back by as much as 24 hours, with the greatest rainfall now expected on Thursday and Friday. The mid/upper level ridge axis over eastern NC will, for the most part, remain in place through Wednesday. On Thursday, the mid/upper level cutoff low over AR starts to move poleward and open up into the longwave flow, resulting in 30m H5 height falls over the NW Piedmont. At the same time, surface winds will shift out of the northeast in response to a building surface high over the NE U.S. and the potential tropical wave off the NC/SC coast. Given thick cloud cover, rainfall induced surface cooling, and the northeasterly flow, expect CAD-like conditions especially for the NW Piedmont beginning Thursday. Another 30m of H5 height falls will likely occur again on Friday as the now open trough begins to progress eastward. Highest rainfall totals are expected along the foothills of the mountains into the western Piedmont with a local minima in the northern Coastal Plain. Highs will be greatly influenced by the CAD-like set up and any breaks in cloud cover, but for the most part, expect highs ranging from the lower to upper 70s. Saturday through Monday: A mid/upper level ridge that will build into the southern Plains and lower MS Valley this weekend will begin to push the mid/upper level trough off the Mid-Atlantic coast on Sunday. Increasing H5 heights of 40-50m on Sunday will limit showers and storm chances to the Coastal Plain on Sunday. Highs will start to creep up into the upper 70s to low 80s as a meso high begins to build into western NC. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... As of 750 PM Monday... Confidence is high that VFR conditions will start the period at all TAF sites. Some lingering isolated showers and storms remain across central NC, but most activity is expected to weaken by late evening with loss of daytime heating. Additional lift overnight into early Tuesday morning from mid-level energy will be concentrated over the western Piedmont, with some -SHRA possible at GSO/INT. Also, consistent with previous forecast package, guidance favors IFR/LIFR CIGs at GSO/INT and fog at RDU/FAY/RWI Tuesday morning given saturated low-levels and calm winds. LIFR CIGs at GSO/INT should lift to MVFR by the early afternoon but may not reach VFR until late in the TAF period. At RDU/FAY/RWI, morning fog should lift to VFR conditions for the remainder of the period. At all sites, there is the chance of isolated to scattered afternoon/evening storms. However, confidence is not high enough to include storms at any one TAF site, so have just introduced VCSH at the moment. Outlook: A moist low-level airmass will remain in place through Saturday as a nearly stationary low pressure system over the MS valley slowly lifts north into the Great Lakes by late week. That will lead to high chances of showers and associated sub-VFR flight restrictions and fog/stratus each day, especially at GSO/INT. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...Hartfield NEAR TERM...Hartfield/CBL SHORT TERM...CBL LONG TERM...AS AVIATION...Kren/GIH
Area Forecast Discussion
National Weather Service Blacksburg VA
833 PM EDT Mon Oct 4 2021 .SYNOPSIS... A storm system will linger along and west of our region through at least Friday, keeping around period of clouds, showers, and thunderstorms. && .NEAR TERM /THROUGH TUESDAY/... As of 820 PM EDT Monday... Lowered probability of precipitation for the rest of tonight... Current radar showed areal coverage of showers and thunderstorms has diminished. HREF and HRRR guidance had much of the precipitation gone by midnight but have not cut out probability of rain entirely. Overnight will be relative lull in the rain before the next short wave backs winds to the southeast and more widespread upslope and isentropic lift begins Tuesday morning, shortly after 12z/8AM then spreads from southwest to northeast across the region throughout the day. Areas of low clouds and fog will develop overnight into Tuesday morning. Low temperatures tonight will range from the lower 50s in the mountains to the lower 60s in the piedmont. Another shortwave will rotate through our area Tuesday generating showers and a few thunderstorms. The SPC Day Two Convective Outlook keeps our region under general thunderstorms. High temperatures on Tuesday will vary from the upper 50s in the mountains to upper 70s to near 80 degrees in the piedmont. && .SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/... As of 110 PM EDT Monday... Cutoff low expected to continue to drift along to our west throughout the short term forecast period. Surface high pressure over the northeastern states will continue to wedge south into the Carolinas and remain in the area into Thursday night. Continued east/southeast flow will bring in Atlantic moisture into the region. Persistent light rain, drizzle, and fog is expected. Went with the lower side of guidance for high temperatures on Wednesday and Thursday as we will be solidly within the cool air wedge, along with continued light rain and cloud cover, which will limit any daytime heating. && .LONG TERM /FRIDAY THROUGH MONDAY/... As of 130 PM EDT Monday... Meandering cutoff low has not made much progression by Friday. East/southeast flow continues to supply Atlantic moisture into our area. Moving into Saturday, details on the forecast become a little more murky in terms of rainfall and the progression of the cutoff low. Cutoff low begins to become absorbed into the overall flow and an elongated trough sets up over the eastern seaboard. The big question for the weekend will be how long can the easterly flow remain, which will in turn be a big factor on how much rain we will ultimately receive. For now, kept a mention of rainfall into Monday, but tapered the coverage down for Sunday and Monday. Temperatures near or just below normal Friday/Saturday, increasing to slightly above normal for Sunday/Monday. && .AVIATION /00Z TUESDAY THROUGH SATURDAY/... As of 830 PM EDT Monday... Coverage of showers and thunderstorms will be at a minimum tonight, but MVFR is expected to develop in most locations throughout southwest Virginia, northwest North Carolina and southeast West Virginia. KLWB has the best potential overnight for IFR/LIFR fog. MVFR to IFR stratus will develop late tonight and through the day Tuesday as deep southeast to east winds develop. Higher elevations of the Blue Ridge south of KROA will be in the clouds. Poor flying weather is likely during at times Tuesday due to low ceilings and fog. Showers and thunderstorms will spread from southwest to northeast across the region on Tuesday. MVFR conditions are likely with these storms. Average confidence in ceilings, visibility and winds. Extended Aviation Discussion... The potential for Sub-VFR conditions will continue until the end of the week. The chance for showers and thunderstorms will persist through the end of this week due to an easterly wind pumping deep moisture into the central Appalachians. Drier air may come into our region Saturday night into Sunday. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...PW/WP NEAR TERM...AMS/KK SHORT TERM...BMG LONG TERM...BMG AVIATION...AMS/KK/WP
Area Forecast Discussion
National Weather Service Las Vegas NV
837 PM PDT Mon Oct 4 2021 .SYNOPSIS...Low pressure moving in from Southern California will spread showers and thunderstorms across areas mainly along and south of Interstate 15 late tonight and into Tuesday. Heaviest rainfall and best chances for thunderstorms will be across San Bernardino and Mohave counties. Another weather system will approach the region late in the week with renewed shower chances and increased wind speeds. Temperatures for the remainder of the week will tend to be below average. && .UPDATE...Diffluent flow northeast of upper low producing widespread showers and thunderstorms from San Diego County northwestward to Santa Barbara County. So far, rainfall amounts running less than a quarter of an inch. Upper low progged to move toward San Diego tonight with that diffluent flow shifting eastward across the Mojave Desert and lower Colorado River Valley where showers and thunderstorms should develop after midnight. All that development should stay along and south of I-15. Upper low will weaken and accelerate eastward into western Arizona late Tuesday afternoon. Steepening lapse rates under cold pool aloft will generate scattered thunderstorms primarily across northwest Arizona, potentially stretching as far northwest into the Lake Mead National Recreation Area. Latest HRRR accumulated QPF still showing up to a 0.50" across eastern Mohave County with latest runs now supporting locally higher amounts of 0.25"-0.50" for the higher terrain of Clark County. Updated the tonight period which lowered the PoPs, or delayed the onset of precipitation for Clark until late tonight or around daybreak Tuesday. && .SHORT TERM...Through Tuesday night. Closed low off the coast of southern California will drift inland late tonight while filling as it pushes into central Arizona. Ahead of this low, diffluent flow aloft will spread increasing clouds northward as far as the southern Great Basin this evening, with increasing shower activity to follow late tonight. As the upper low and associated cold pool lifts into the southern Mojave Desert tomorrow, steepening lapse rates and breaks in the cloud cover will result in conditions becoming increasingly unstable, and pockets of showers and thunderstorms will form under the cold pocket aloft, particuarly across Mohave county which will be near the cold core center. Brief heavy downpours and a few instances of small hail/graupel will be possible as the low moves through Tuesday afternoon. Through the duration of the storm system, chances for precipitation will be focused along and south of the I-15 corridor, with precipitation coverage becoming increasingly spotty with northward extent. Precipitation amounts overall will be quite light, with between a trace and a tenth of an inch of rain for most of the Mojave Desert region along and south of I-15, including Las Vegas. Higher amounts of a quarter to a half inch will be most favored in Mohave County from Kingman eastward. The low will lift east Tuesday evening, with shower activity diminishing with the loss of daytime heating and increasing subsidence behind the departing low. .LONG TERM...Wednesday through early next week. The weather pattern looks to remain active through early next week, resembling a more typical late fall or winter pattern than early October. As Tuesdays storms system lifts east, another trough will reload off the West Coast by midweek before penetrating inland late in the week. There remains uncertainty in the depth of this next trough, but additional shower chances will likely spread into at least the high terrain by Friday along with increasing southwesterly surface winds. This system will be a little colder than the previous, and could spread some high elevation snow into the Sierra as it moves through. Dry and cool conditions will follow for the weekend, but yet another, potentially even deeper trough is advertised by the forecast guidance by early next week. In summary, dust off the jackets, fall temperatures are right around the corner. && .AVIATION...For McCarran...Winds will follow diurnal patterns overnight and Tuesday morning before becoming more south or southeast Tuesday afternoon. Speeds should remain at 8KT or less through the period. There is a very low chance for sudden gusty winds from nearby outflows Tuesday morning, potentially from the south or southeast. A system will move through on Tuesday and will bring periods of rain and lower ceilings to the terminals. Isolated showers are possible after 09Z Tuesday are ceilings down to around 10kft are likely with the early morning precipitation. More widespread showers are then expected late Tuesday morning through the afternoon, with ceilings 6000-8000ft possible at times. Isolated thunderstorms are also possible Tuesday afternoon, but confidence is too low at this time to include TS in the TAFs. Moderate rain, lower CIGs to 5000ft, and small hail would be possible with any thunderstorms that moved over the terminals. Precipitation is expected to end Tuesday evening, with conditions improving overnight. For the rest of southern Nevada, northwest Arizona and southeast California...Increasing clouds with ceilings between 10kft-15kft are expected through the evening across the region. The chances for showers and lower ceilings to around 10kft will begin south of Interstate 40 around 06Z and spread northeast through Tuesday. The only TAF site that will definitely remain dry through Tuesday is BIH. A few thunderstorms are possible as well, especially Tuesday afternoon in far southern Nevada and western Arizona. Ceilings to around 8000ft and mountain obscuration will be possible with any showers, and lower ceilings down to 5000ft, small hail, and moderate rain would be possible with any thunderstorm. Conditions will improve Tuesday evening and overnight as rain ends from southwest to northeast. && .SPOTTER INFORMATION STATEMENT...Showers and thunderstorms are likely to impact areas mainly along and south of I-15 Tuesday. Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Pierce DISCUSSION...Outler AVIATION...Nickerson For more forecast information...see us on our webpage: or follow us on Facebook and Twitter