Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 03/02/19


See below for an aviation forecast discussion for the 00Z TAFs.

UPDATE Issued at 438 PM CST Fri Mar 1 2019 Dropped the winter weather advisory over the southeastern forecast zones. Just some flurries left now. But, across the entire forecast area since late last night, 1 to 4 inches have been reported throughout the forecast area, with some 3 to 5 inch reports showing up across where there was an advisory in place. && .SHORT TERM...(This Evening through Saturday Night) Issued at 313 PM CST Fri Mar 1 2019 The snow along and east of the James valley will continue to transition east through the afternoon, with advisory level accumulations. There will be a lull this evening with clearing and a light north wind that will allow for some temperature drop before the next batch of clouds move in. A weak system moves mainly west of the Missouri valley, with dry air in the east limiting the eastward extent. Only looking at about 1-2 inches of fluff in the far western CWA. Otherwise winds pick up Saturday with mixed winds topping out around 20kts, plus cold advection as a ridge of high pressure slowly builds across the region. There is some mention of blowing snow but light drifting will generally impact road conditions more than anything else. .LONG TERM...(Sunday through Friday) Issued at 313 PM CST Fri Mar 1 2019 The extended period starts off with very cold air in place over the region. Temperatures will start off in the teens below zero early Sunday morning, with wind chills in the -25 to -40 range. Bitterly cold wind chills will remain a concern through the day Monday as the region remains on the east side of a strong surface ridge, with wind gusts up to 30 mph Sunday afternoon through the day Monday. May still see some gusts up to 20 mph or so on Tuesday, then the surface high slides across the area, with lighter winds Tuesday night into Wednesday. The next chance for snow comes Wednesday night into Thursday as a low pressure system tracks across the Central Plains. High pressure returns Friday, with dry conditions expected. After the very cold start to the day Sunday, will only see temperatures rise to the single digits below and above zero Sunday afternoon. Will then see a gradual warm up through the period, with highs in the single digits above zero on Monday, in the teens to lower 20s Tuesday through Thursday, and in the upper teens to upper 20s Friday. && .AVIATION...(For the 00Z TAFS through 00Z Saturday Evening) Issued at 540 PM CST Fri Mar 1 2019 Things have cleared off or are in the process of clearing off, with good VFR anticipated for much of the next 6 hours. However, short range/rapid update guidance continues to suggest that by 12Z Saturday, lower (sub-VFR) CIGS will develop/move into the area. A low pressure system will also work its way southeastward across the front range and northern high plains, generating some light snow and MVFR vsbys for KMBG/KPIR from early Saturday morning through Saturday afternoon. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...None. MN...None. && $$ UPDATE...Dorn SHORT TERM...Connelly LONG TERM...Parkin AVIATION...Dorn
Area Forecast Discussion
National Weather Service Boston/Norton MA
953 PM EST Fri Mar 1 2019 .SYNOPSIS... Coastal storm tonight into Saturday with mostly snow, a wintry mix with rain along the immediate south coast of New England. Some blustery northeast winds as well. A second storm Sunday night into early Monday will bring snow, likely changing to rain in the coastal plain. Significant snow accumulations possible in the interior. Mainly dry weather, but much colder for the rest of the coming week with temperatures well below normal. && .NEAR TERM /THROUGH SATURDAY/... 10 pm update ... Sticking with the going forecast. An eye on how quickly N Gulf mid-level energy shears downstream out ahead of additional Pacific energy ejecting E from the Rockies. Monitoring the longevity of frontogenesis N/NE of the closing H9-8 low extending on up thru the dendritic growth zone with omega values of 5-10 microbars per second. Saturated column throughout, the grasp of N Gulf energy and higher precipitable waters crucial as to what can be frontogenetically lofted and squeezed out beneath upper level support of a RRQ of a neighboring H3 jet streak N/E. Latest satellite showing ingredients coming together in a nice mini- baroclinic leaf structure. Starting to see some W-E fronto- genetical banding along the immediate S-coast coincident with the clash of higher precipitable waters as surface high pressure lingers to the N/E. Likely will see continued evolution as most of the high-res guidance indicates over S/E areas of S New England, but it`ll be interesting if more robust moisture is sheared out E over the waters, or rather if convection, ongoing well E of the Delmarva Peninsula, can rob the environment N. Following HRRR trends closely. Still some concern that outcomes could turn out slightly less as moisture / synoptics are stretched E. As alluded to below, a shorter residency time of outcomes would subsequently limit snowfall accumulations. Previous discussion ... Plowable snowfall late tonight into Saturday. Low pressure over the southeastern states emerges off the Carolina coast, steadily deepening and strengthening as it tracks toward our area. 12Z GFS tracks the low center over the 40N/70W benchmark, 12Z NAM and ECMWF bring the low center slightly SE of the benchmark during Saturday morning. Some favorable dynamics for this deepening low, with SNE getting into right rear quadrant of upper level jet. However looking at the mid levels, flow shows short wave energy but it is traversing thru a fast flow with only a modest amount of mid level troughing and a lack of a downstream block. This will keep this system progressive, moving steadily thru and then NE of our area during late tonight thru Saturday afternoon. The expedient track of this low brings a challenge to determining snowfall amounts, the shorter residence time limiting accumulations. Although models not fully consistent on QPF amounts, there is model agreement that the highest QPF will be over SE MA, with amounts tapering over the interior. Heaviest snow expected to fall between 4 am and noon. Marginal thermal fields indicate the potential for a heavier, wet snow over SE MA and RI, and some wintry mix closer to the coastline as well as the Cape/Islands. Precip type all snow over the interior, where the snow to liquid ratios will be higher. A Winter Storm Warning is now in effect for Bristol and Plymouth Counties in MA for 4 to 7 inches of snow. Then a Winter Weather Advisory is in effect for the remainder of the BOX County Warning Area, except for a portion of NW MA and also Nantucket where amounts are expected to be lower (in Nantucket`s case, mixing with rain). Generally a 3 to 6 inch event in the Advisory area. Winds will be out of the NE, becoming N and increasing during the day Saturday. Gusts 20 to 30 mph along the east coastal MA and coastal RI locales, except gusts 30 to 40 mph Cape and Islands. With surface dewpoints in the teens and low 20s, there will be some wet bulbing overnight as precip approaches. Looking at overnight lows mainly in the 20s, except around 30 Cape and Islands. Highs on Saturday mostly in the low to mid 30s, except upper 30s on Nantucket. && .SHORT TERM /SATURDAY NIGHT/... Saturday night... The coastal low continues to rapidly deepen but is moving steadily away from our area, east of Halifax by 06Z. There is the potential for some lingering wraparound light snow during the evening, and have slight chance to chance pops for that timeframe. Then after midnight, dry with partial clearing as surface ridging briefly moves into our area. Winds shift from the North to the West and become light. Seasonably cold with lows mainly in the 20s. && .LONG TERM /SUNDAY THROUGH FRIDAY/... Highlights... * Another coastal storm will likely bring significant snow accumulation to the interior Sunday night into early Monday * Snow likely changes to rain near the coast * Much colder for the rest of next week with temps well below normal Sunday... Dry weather holds on for much of the day as high pres gradually shifts to the east. Clouds will be increasing and some light snow may reach western MA/CT toward evening, otherwise a dry day with highs in the 30s to around 40. Sunday night into Monday... High confidence that a winter storm will impact the region but there is still uncertainty with respect to specific details regarding where rain-snow line sets up and specific snow accums across the region. GFS remains furthest south and east with low track near the benchmark and coldest of the guidance and would suggest significant snowfall across the coastal plain. ECMWF is furthest north with track across the Cape with heaviest snow in the distant interior with rain-snow line getting west of the I-95 corridor. NAM is somewhat of a compromise. Given the lack of a blocking downstream ridge and mean trough axis back across the Lakes, we think GFS is to far offshore so favored a track closer to the ECMWF but will blend with NAM thermal profiles as a basis for the forecast. Enough cold air in place for precip to start as snow across all SNE Sun evening, but expect an eventual change to rain overnight along the south coast and the coastal plain near the I-95 corridor from PVD to BOS with mostly snow to the north and west. This area has greatest uncertainty regarding snowfall amounts as ptype transition zone expected to be nearby. A period of heavy snow with 1-2"/hr snowfall rates will possible in the interior overnight Sun night but duration of heavy snowfall rates should will be limited as this will remain an open wave with no closed mid level low developing. Regarding snowfall, prelim thinking is max snowfall axis of 6-10" across the interior west of I-95 corridor, with highest amounts across interior MA and portions of northern CT. Expect 4-7" along the I-95 corridor into interior SE MA, 2-4" PVD-TAN-PYM and 1-2" near the south coast. However, it is important to note that any shift in the storm track will result in changes to these numbers. There is a risk of isolated to scattered power outages, especially from northern CT, NW RI through NE MA where risk of 6+ inches of wet snow. The snow should be drier further back across central and western MA with lower risk of power outages here. The heaviest snow should be winding down Mon morning, but there will be a significant impact to the morning commute, especially in the interior with snow covered roads. Tuesday through Friday... Unseasonably cold airmass settles over New Eng with 850 mb temps 2-3 SD below normal. The coldest period should be around Wed/Thu with 850 mb temps down around -20C. Looks mostly dry during this period with NW flow aloft, but will have to watch next approaching shortwave and low pres which could bring more snow/wintry precip sometime late Fri into Sat. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Saturday Night/...High confidence. Tonight into Saturday... SN spreading north across the terminals 06-10z. Wintry mix with IP/RA along the immediate S-coast, Cape and Islands. MVFR-LIFR impacts, especially with SN, to both CIG and VSBY. SE winds becoming NE overnight, increasing to 10 to 20 sustained along E/SE New England. During Sat, gusts 25 to 30 kts eastern MA/RI, except gusts 30 to 35 kts possible Cape/Islands. Saturday night... Lingering MVFR cigs with some light -SN possible during the evening. Then becoming VFR after midnight with partial clearing. KBOS Terminal... VFR, then lowering cigs/vsbys late tonight with SN moving in around 10Z Saturday, diminishing after 20Z. Expect reductions in both CIGs and VSBYs as SN accumulates on runways anywhere around 3 to 6 inches. KBDL Terminal... VFR, then lowering cigs/vsbys late tonight with SN moving in around 10z Saturday and persisting thru 17Z. Looking at accumulations on runways of 2 to 4 inches. Outlook /Sunday through Wednesday/... Monday: MVFR/IFR conditions possible. Windy with local gusts up to 30 kt. Chance SN. Monday Night through Wednesday Night: VFR. Breezy. Thursday: Breezy. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Saturday Night/...High confidence. Tonight... Low pressure system emerges off the Carolina coastline tonight, strengthening as it tracks towards the coastal waters. Winds/seas increase overnight, Shifting from the S to E/SE with gusts 25 to 30 knots on the southern coastal waters late tonight. Seas on the southern waters building to 3 to 6 feet. Reduced vsbys late in areas of rain and snow. Saturday... Gale Warnings in effect for the southern outer coastal waters and waters east of Cape Cod, as well as Nantucket Sound. NE winds becoming N, intensifying with gusts up to 35 kts. Elsewhere along the waters, SCA headlines hoisted with gusts to 30 kts during the day. Seas 5 to 10 feet. Reduced vsbys in areas of rain and snow, mainly in the morning. Saturday night... Coastal Storm rapidly pulls NE-ward away from our area. Will still have some gusts to 25 kts to start, along the outer coastal waters. Then winds diminish during the overnight. Outlook /Sunday through Wednesday/... Monday: Moderate risk for Small Craft Advisory winds with areas of gusts up to 30 kt. Rough seas up to 10 ft. Chance of rain. Local visibility 1 to 3 nm. Monday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Tuesday: Winds less than 25 kt. Seas up to 5 ft. Tuesday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Local visibility 1 to 3 nm. Wednesday through Wednesday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. Slight chance of snow showers. Local visibility 1 to 3 nm. Thursday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of seas approaching 5 ft. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...Winter Weather Advisory from 1 AM to 7 PM EST Saturday for CTZ002>004. MA...Winter Weather Advisory from 1 AM to 7 PM EST Saturday for MAZ004>007-009>016-022-023-026. Winter Storm Warning from 1 AM to 7 PM EST Saturday for MAZ017>021. RI...Winter Weather Advisory from 1 AM to 7 PM EST Saturday for RIZ001>008. MARINE...Gale Warning from 7 AM to 6 PM EST Saturday for ANZ232. Small Craft Advisory from 3 AM to 7 PM EST Saturday for ANZ233- 234. Small Craft Advisory from 7 AM to 5 PM EST Saturday for ANZ230. Small Craft Advisory from 6 AM Saturday to 3 AM EST Sunday for ANZ231-251. Small Craft Advisory from 6 AM to 5 PM EST Saturday for ANZ236. Small Craft Advisory from 3 AM Saturday to 3 AM EST Sunday for ANZ235-237. Small Craft Advisory from 6 AM Saturday to 5 AM EST Sunday for ANZ250. Gale Warning from 7 AM to 7 PM EST Saturday for ANZ254>256. && $$ SYNOPSIS...KJC/NMB NEAR TERM...KJC/Sipprell/NMB SHORT TERM...NMB LONG TERM...KJC AVIATION...KJC/Sipprell/NMB MARINE...KJC/Sipprell/NMB
Area Forecast Discussion
National Weather Service State College PA
1059 PM EST Fri Mar 1 2019 .SYNOPSIS... Another fast moving weather system will bring a 4 to 8 hour period of snow across Central and Southern Pennsylvania tonight, along with some areas of light freezing rain across the Laurel Highlands and Southeastern PA. After a quiet weather day Saturday, a digging trough over the Miss Valley will spawn a more significant storm system lifting up the east coast late Sunday into early Monday, bringing more widespread and potentially heavier snowfall. An anomalous upper level trough will then pivot across the northeast CONUS next week keeping temperatures below average. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... Northern edge of precipitation shield has been slow to reach the Central Mountains and latest HRRR trends seem to be outperforming the more robust earlier solutions from NAM12 and GFS/ECMWF. Have shaved POPs and snow chances generally to NIL from I80 northward as a result. Farther south, precip began as a snow and freezing rain mix across the southern tie as expected. Did lift the mixing area farther north into the Lower Susq through late evening, but as precip rates increase after midnight, predominate ptype is still expected to be snow with general 1 to 3 inch amounts. Advisory level snow is expected for the southern tier overnight. The milder air will continue to create a Ptype problem along and south of the Mason Dixon line overnight. But a solid 2-3" of snow is likely across the I-81, I-78 corridor overnight until sunrise. Across the Laurel Highlands temps just aloft rise above freezing which will bring some light freezing rain, mainly for Somerset County. Elsewhere, accumulations should be minimal with the northern edge of the light snow not reaching the northwest mountains. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... Behind the tonight`s system will be a break in the weather with improving conditions and milder air over the region for Saturday. Temperatures will rise back towards average for early March with reading in the mid 30s north to mid 40s south. After a quiet night on Saturday clouds increase early on Sunday ahead of the next storms system. Look for clouds to thicken and lower during the day with snow developing in the afternoon from SW to NE. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... There high confidence for a more significant winter storm impacting most or all of the region Sunday. First off, as an upper trough digs over the Miss Valley, all medium range guidance continues to hone in on tracking a developing surface low from the Gulf Coast states/Lower Miss Valley northeast to the Delmarva Peninsula by late Sunday night. With lack of a blocking high to our northeast, we don`t anticipate a major storm and a somewhat quick-hitter. That being said, the latest 09-12Z operational/ENS model guidance indicates a notable, and progressive coupled jet circulation over the Ohio River Valley and Cent Appalachians Sunday morning, lifting NE across PA Sunday afternoon through at least the first half of Sunday night. Large scale forcing gradually wanes late Sunday night and early Monday as the 994 to 988 MB sfc low move to the southeast shore of Long Island by daybreak Monday. Multi-model consensus storm track via the EC/NAM and FV3-GFS is in a remarkably tight range (right over Southern/Central DE, with the GFS being the furthest south by about 100-150 NM, and the GEFS being the compromise right over KORF at 08Z Monday. A plowable snow of 3-5 inches is likely over a good portion of the forecast area Sunday PM/early Monday morning, with the potential for over 6 inches. With the aforementioned sfc low track over the Delmarva (and the elongated 850 mb low track near the I-81 corridor), ptype could be either snow or rain across the Lower Susq Valley (with only a thin ribbon of sleet possible). EC`s Max wet bulb in the 1000-700 mb layer is about +1-2C as far north as the I-81 Corridor for a few hours around midnight local time Sunday night, and should be warm enough to cause a mixture of rain or sleet to fall for a short time near KTHV and KLNS to hold down snow accums by a few inches or more (to mainly advisory levels). Following the winter storm to kick off the workweek will be an even a higher (near certainty) confidence for a several day- long cold outbreak for Monday-Wednesday, with daytime highs running 10-15 deg F below normal and similar departures for overnight mins based on ensemble 850 temps 1-2SD below climo and ECM MOS. The upslope/Lake Effect stratocu clouds during the first half of next week will have temps within the favorable thermal ribbon (of -12 to -18C) for dendritic snow growth, so frequent snow showers will light additional accums per each 12 hour period will occur across the Alleghenies of northern and western PA. As the mid to late wee period nears there will likely be refinement of the snow accums from upslope and LES across the NW Mtns and Laurel Highlands. The large area of high pressure will drift east and over the Mid Atlantic Region Thursday into early Friday with fair and mainly dry conditions. Longer range glance indicates another winter storm possible for next weekend March 9-10. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... Low-level moisture keeping ceiling reductions in place overnight into mid Sat morning. Weak weather system will impact southern portions of CWA starting late this evening with a period of light snow or mixed precipitation into the predawn hours, with precip lingering the longest over the lower Susq. Expect a 4-8 hour period of reduced visibilities (to go along with cig reductions), followed by improving conditions behind this system on Saturday as flow shifts around to westerly. Outlook... Sat...Reductions areawide early. Then MVFR NW. BCMG VFR elsewhere. Sun...Restrictions likely developing due to snow over most of the area/rain & snow SE. Mon-Wed...MVFR/sct SHSN poss W, No sig wx elsewhere. && .CTP WATCHES/WARNINGS/ADVISORIES... Winter Storm Watch from Sunday afternoon through Monday morning for PAZ006-010>012-017>019-037-041-042-045-046-049>053- 057>059. Winter Weather Advisory until 7 AM EST Saturday for PAZ033>036- 056>059-063>066. Winter Storm Watch from Sunday morning through Monday morning for PAZ024>028-033>036-056-063-064. && $$ SYNOPSIS...Ross NEAR TERM...Ross/DeVoir SHORT TERM...Ross LONG TERM...Fitzgerald/Lambert AVIATION...Ross/RXR
Area Forecast Discussion
National Weather Service Lincoln IL
837 PM CST Fri Mar 1 2019 .UPDATE... Issued at 837 PM CST Fri Mar 1 2019 Cold front currently pushing into eastern Iowa is triggering a line of radar echoes from northern Illinois W/SW into northern Missouri. So far this evening, have only seen reports of precip reaching the ground at the northern end of the line...mainly north of I-80. Further southwest, relatively dry boundary layer airmass has prevented precip. Latest HRRR shows zero measurable precip as the front pushes into central Illinois overnight, but based on radar trends cannot rule out a few snow flurries. Have therefore updated the forecast to go with scattered flurries across the northern two-thirds of the KILX CWA as the front approaches. Other than that, it will be a cloudy and cold night with lows mostly in the middle to upper 20s...except lower 30s south of I-70. && .SHORT TERM...(This evening through Saturday) ISSUED AT 258 PM CST Fri Mar 1 2019 Mostly sunny skies will continue through the remainder of the afternoon across central Illinois, however, low clouds continue to linger in southeast Illinois as saturated soils remain an issue. A weak disturbance will slide by in northern Illinois this evening, although no accumulation is expected from this, I added a slight chance of PoPs to the forecast, in case some flurries are seen. Low pressure will move onshore Saturday (west US) and collide with a winter system dropping into the west, then quickly advance to the Plains Sunday morning. As this system moves through the Plains, it will pick up moisture from the Gulf of Mexico. .LONG TERM...(Saturday night through Friday) ISSUED AT 258 PM CST Fri Mar 1 2019 Precipitation will arrive into the Midwest around 06-09z Sunday, well ahead of the main low core. Most of the precip will fall as snow, but a change was made in temperatures across locations south of I-70, providing a chance of rain/snow mixture. As the low deepens Sunday, it will approach the Tennessee Valley region Sunday afternoon. Model trends continue to tighten the snowfall gradient and decrease amounts across central Illinois. New totals show 1-2 inches falling from PIA to ILX- CMI, while locations south of I-72 and north of I-70 will see 2-3 inches, and south of I-70 will see 3-4 inches. The highest amounts of snow are forecast to fall between 09-18z Sunday, as the front side of the system moves through. This system will then quickly slide out of the region Sunday evening, with all precipitation done by 03z. Behind the system, another blast of cold air will filter into the region, as Arctic High pressure dominates the northern Plains through the Midwest. A 1042mb High pressure system will set up in the northern Rockies and linger over the first half of next week. This will cause temperatures to plummet behind the exiting system, with forecast lows Monday and Tuesday morning in the single digits, while wind chill values drop to -10 to -20 around much of the area. Highs will only reach the teens Monday and low 20s Tuesday, but another winter warmup arrives mid-week. As the High drops through the Plains and into the mid-Mississippi Valley region, it will continue to hold strength, as a 1035mb High on Wednesday. Dry conditions will hold through mid- week as well, before another system arrives late week. && .AVIATION...(For the 00Z TAFS through 00Z Saturday evening) Issued at 552 PM CST Fri Mar 1 2019 VFR conditions currently prevail at the central Illinois terminals:however, MVFR ceilings are poised along/southwest of a KEOK to KIJX line and will advect slowly northeastward as the evening progresses. Based on HRRR forecast, it appears ceilings will lower to MVFR at KSPI by 03z...then further northeast to KCMI by around 09z. While HRRR tends to keep lower clouds around through the remainder of the 00z TAF period, the NAM suggests once winds veer to the NW behind a departing surface trough, ceilings will temporarily scatter Saturday morning. Based on upstream satellite trends, have decided to go with the more optimistic NAM and scatter the ceilings from west to east across the area between 11z and 17z. Winds will initially be light and variable tonight, then will become northwesterly at 8-12kt on Saturday. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...Barnes SHORT TERM...Baker LONG TERM...Baker AVIATION...Barnes
Area Forecast Discussion
National Weather Service Jackson MS
846 PM CST Fri Mar 1 2019 ...STRONG TO SEVERE STORMS LIKELY ON SUNDAY FOLLOWED BY MUCH COLDER TEMPERATURES EARLY NEXT WEEK... .UPDATE... Updated for evening discussion. && .DISCUSSION... Looking at the latest IR Sat, mid-level clouds moving in were getting quickly eroded by dry air over the eastern half of MS. JAN`s RAOB had a fairly dry column, but upstream LZK`s RAOB was starting to moisten up to 850mb. This moist air has been slow to really advect into the region and the regional radar mosaic confirmed very little to any precip. HRRR was showing some precip by 03Z, but this hasn`t materialized, so thinking it best to lower pops just a bit over the entire area. Isolated showers are still possible with up to a tenth of an inch of QPF. There may be some patchy fog, but don`t see temps over much of the area reaching the fog point. Temps should stay on track considering there will still be ample cloud cover over most of the area, so didn`t make any changes to lows. /LM/TP Prior discussion below: Tonight and Saturday: Mid afternoon surface analysis had a nearly stationary front across southern Forest county and a 1020mb high centered over east Arkansas. This surface high will provide just enough of a push to shift the nearly stationary boundary southeast of our CWA. A cooler and much drier airmass has settled over most of the CWA and cloud cover has helped hold temperatures in the 40s across our north and in the 50s across the central portions of our area so far this afternoon. There may be a shower or two during the next few hours across our southeast but this potential will end by evening. Light rain will return from the west later this evening though as a weak disturbance within our zonal flow aloft moves across the region. This light rain will end by mid morning as the disturbance moves east of Mississippi. Although the rain will end Saturday morning, there will remain plenty of cloud cover through the afternoon. Despite the cloud cover, temperatures will be milder and make it into the 60s across most of the area with lower 70s across the south. /22/ Saturday night through Thursday: Going into Sunday, a fast-moving shortwave trough will cross into the Southeast as part of a broad upper-level trough over the central U.S. Ahead of the shortwave and at the surface, a cutoff low is expected to develop and allow a broad warm sector to move over the area. Within this sector, the moist boundary layer will provide sufficient moisture to feed storms with heavy rainfall. As the system approaches our area from the west late Saturday night/early Sunday morning, some activity will move in that will have the potential to develop some elevated hail in our western counties/parishes. Instability increases throughout the day though and decent CAPE values of 1500 j/kg and strong deep-layer shear of 35-40kts will support better organized strong to severe storms. Threats will include flash flooding (mostly due to the antecedent soil conditions in conjunction with heavy downpours), damaging wind gusts, hail, and tornadoes. Now, the models differ a bit in that the bulk of the precip seems to be located in the heart of the cutoff low where the greatest convergence is with the GFS while with the Euro it is located along the front where the greatest forcing is. The Euro shows slightly stronger severe parameters. Overall, we didn`t see a need to make any changes to the hazardous weather outlooks at this time. On the backside of the frontal passage, cold arctic air will surge into the area and force temperatures down 15-20 degrees below normal values for the first part of next week. These cold temperatures will be a bit of a shock to the region as we haven`t seen freezing temps since mid-February and plants and trees are starting to bud and bloom already. Low temps will fall into the 20s for at least two nights, including Monday and Tuesday night. Highs will mostly be in the 40s. The arctic surface high finally pushes off to the east on Wednesday though and temps begin to rebound back to normal in the latter part of next week. /10/ && .AVIATION... 00Z TAF discussion: No big changes to the forecast overnight. Looking for MVFR to LIFR ceilings to prevail across the region. Guidance shows rain moving through the area as a wave passes, but there wasn`t much developing upstream. Could see some light rain move across each site with minimal impacts. Patchy fog may develop also, but should be within the MVFR-LIFR range early Saturday. Low ceilings may lift for a few hours in the afternoon. && .PRELIMINARY POINT TEMPS/POPS... Jackson 48 69 55 70 / 35 20 60 99 Meridian 49 68 54 71 / 35 21 48 99 Vicksburg 47 66 55 66 / 35 12 71 98 Hattiesburg 58 74 60 76 / 21 22 28 97 Natchez 50 70 59 71 / 35 21 56 99 Greenville 42 60 50 54 / 22 3 90 99 Greenwood 42 63 50 58 / 35 3 81 99 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$
Area Forecast Discussion
National Weather Service New Orleans LA
749 PM CST Fri Mar 1 2019 ...SOUNDING DISCUSSION... This evening`s balloon launch was successful with no problems encountered. This launch was performed in the warm, unstable airmass ahead of an approaching weak cold front from the northwest. This sounding sampled a rather deep, moist airmass in place with SBCAPE ~1500J/kg, with a distinct moist-adiabatic thermal profile from the well-mixed planetary boundary layer to the low to mid-levels. Comparing this sounding to the previous 12 hours shows an interesting transition in the mid-levels. A weak subsidence inversion at 12Z this morning around 580mb has descended, and warmed due to compression/subsidence to a base of 640mb illustrating a stable airmass in this layer. However, above this layer, upper- level moisture continued to advect along a quasi- zonal phased jet pattern dragging in a thin cirrus deck aloft. Earlier this afternoon, a few areas of showers did develop across SE LA and S MS, but with no distinct dynamic trigger in place (other than surface frontogenisis well to the NW), these showers remained weak and didn`t ascend deep enough to produce much lightning or become strong. Since these showers were primarily diurnally driven by building thermodynamics this afternoon, all this shower activity has ended, with only some areas of marine convection remaining. So for tonight, look for the aforementioned frontal boundary to continue to slowly press south and east across the area, then stall right through the heart of SE LA. Latest HRRR trends do show some isolated showers trying to develop close to sunrise, but lack of surface based thermodynamics will mean these will be fueled only by frontal forcing and deep moist flux transport from the gulf, which means these will be isolated, and should be rather light. However, guidance also supports this weak stationary boundary to eventually drift back north as a warm front later Saturday afternoon, where enough sunshine in the warm sector will build instability back again with isolated showers, and perhaps a few thunderstorms late Saturday into Saturday evening. Good news is it will not be an all day washout, and like today, should dry out by later evening and overnight tomorrow night. KLG && .PREV DISCUSSION... /issued 356 PM CST Fri Mar 1 2019/ .SHORT TERM... Scattered convection developing along and south of a weak boundary extending from Morgan City to Slidell to Lucedale will persist through the late afternoon and early evening hours before dissipating. This convection is largely being forced by daytime heating, and as temperatures cool after the sun sets, the amount of shower activity will diminish. By late evening, a dry forecast is called for. However, the warm and humid airmass combined with light onshore winds will support the development of fog tonight. Dense fog does not look to be very widespread, and have opted to not issue a dense fog advisory at this time. Temperatures north of the boundary should cool into the middle to upper 50s, and temperatures south of the boundary should cool into the lower to middle 60s. Morning fog should begin to lift by mid to late morning, and then a mostly cloudy sky with isolated to scattered rain showers should develop as temperatures warm back into the 70s. Overall coverage should be slightly lower than today, and a lack of instability should keep the risk of thunderstorms at bay. Lapse rates will basically be moist adiabatic, and MLCAPE values will only climb to around 200 J/KG in the afternoon. These values will not support the deeper updrafts needs to support thunderstorms. The shower activity should once again begin to dissipate in the evening hours as daytime heating wanes. As the showers come to an end, another round of fog should begin to develop as the atmosphere remains warm and moist. Dense fog should not be as prevalent due to a gradual increase in atmospheric buoyancy through the overnight hours in advance of an approaching longwave trough. Overnight lows will dip into the lower to middle 60s. Sunday will be the most active day throughout the entire forecast period as the longwave trough and an associated strong cold front sweep through the region. Initially, a band of showers and thunderstorms should sweep through the northern half of the forecast area Sunday morning. This band of showers and thunderstorms will be associated with a fast moving upper level vort lobe swinging out in advance of the main longwave trough. Fortunately, a weak low level stable layer of air combined with the diurnal minimum and weaker mid-level lapse rates should keep most of the thunderstorm activity below severe limits. However, a relatively low wet bulb zero height and 0-3km speed shear for areas north of I-12 could allow an isolated severe thunderstorm to develop. By early Sunday afternoon, the actual cold front and longwave trough axis will begin to move through the forecast area. Have the highest POP values between 18z and 21z extending from Lafayette to McComb, and this is also the most likely area to experience severe thunderstorm during this time of day. Steep mid-level lapse rates, ample CAPE, a low wet bulb zero height, low LCL, and decent low level shear should support all convective modes with hail, straight line winds, and a few tornadoes possible over the aforementioned area extending from from Lafayette to McComb including metro Baton Rouge. By late Sunday afternoon from 21z to 00z the most likely area for convection and severe thunderstorm development will generally extend along a line from the Houma area through metro New Orleans and across coastal Mississippi. The severe threat looks slightly lower for areas south of Lake Pontchartrain with higher lifted condensation levels, lower CAPE values, and lower shear values expected. As a result, any severe thunderstorms will be far more isolated and likely less intense than those across the Northshore and Mississippi Gulf coast where shear and instability values are more favorable for severe thunderstorm activity. Temperatures in advance of the front should easily climb into the upper 70s. After 00z, the band of convection and the parent trough axis and cold front will begin to push offshore. Strong to severe thunderstorms will persist through the early evening hours coastal portions of Southeast Louisiana and Mississippi, but conditions are expected to stabilize to showers by late evening in these areas. Further to the northwest, skies will begin to clear after midnight and a surge of much colder air will advect in. Overnight lows should bottom out in the upper 30s and lower 40s across the northwest CWA and the middle to upper 40s over the southeast CWA. .LONG TERM... A zonal flow regime will linger over the area through Monday night, and expect to see partly cloudy skies persist. However, a very dry and stable airmass will continue to advect into the low levels of the atmosphere. As a result, any cloud cover should have a fairly high base, and any precipitation that tries to fall out of these clouds will evaporate before reaching the ground on Monday and Monday night. Temperatures will be significantly cooler with highs in the low 50s on Monday and lows ranging from the upper 20 to the lower 40s Monday night. Tuesday will see increased negative vorticity advection and subsidence develop aloft, and this will finally completely clear out the skies. These clear skies combined with the dry air advecting into the region will allow overnight lows to cool into the upper 20s and 30s Tuesday night. Highs on Tuesday will only warm into the lower 50s as a pool of cooler air lingers over the Gulf South. Deep layer ridging will dominate the region on Wednesday and Thursday with mostly clear to partly cloudy skies, low humidity values, and gradually modifying temperatures expected. Highs will warm from the 50s on Wednesday into the 60s on Thursday, and lows will be about 10 degrees warmer Wednesday night as compared to Tuesday night. By Thursday night, increased onshore flow and warm air advection will keep temperatures in the low to middle 50s. An elevated inversion should also produce some clouds during the overnight hours. All of the model guidance indicates that a weak and fast moving short wave feature will slip through the forecast area on Friday. Have a slight chance of showers and thunderstorms in the forecast to reflect this passing system. Temperatures should warm back into the 70s, and this should produce just enough low level instability to support a few thunderstorms in the afternoon hours. .AVIATION... MVFR level cloud bases bouncing between SCT-BKN ad most locations this afternoon. Some diurnally driven convection focused primarily along quasi-stationary frontal zone along KMOB- KNEW-KHUM axis with most of the activity likely to diminish by 02/01Z. Some lowering of cloud decks and some marine layer fog to develop overnight for IFR and some LIFR conditions through about 15Z most terminals, then improving to MVFR levels generally by 18Z through 03/00Z. 24/RR .MARINE... Weak frontal zone extends from Mobile Bay to near New Orleans to lower Atchafalaya Bay is nearly stationary but may sag a bit farther south before completely washing out. This may induce some thunderstorms in the coastal waters tonight. Otherwise, relatively light winds and low seas outside thunderstorms into early Saturday. Onshore flow gradient increases Saturday to moderate levels in advance of approaching strong cold front. Front moves off the coast Sunday night and may be accompanied by a squall line of storms. Cold high pressure then builds Monday and Tuesday into the gulf with strong offshore flow and rough seas to warrant small craft advisories possibly before the front in the tighter gradient but certainly post-frontal with the cold air advection. 24/RR .DECISION SUPPORT... DSS code: Blue. Deployed: None. Activation: None. Activities: Ongoing river flooding and parade safety support Decision Support Services (DSS) Code Legend Green = No weather impacts that require action. Blue = Long-fused watch, warning, or advisory in effect or high visibility event; Marginal risk severe or excessive rain. Yellow = Heightened impacts with short-fused watch, warning or advisory issuances; radar support for slight risk severe or excessive rain. Orange = High Impacts; Enhanced risk severe; nearby tropical events; HazMat or other large episodes. Red = Full engagement for Moderate to high risk of severe and/or excessive rainfall, or direct tropical threats; Events of National Significance. && .PRELIMINARY POINT TEMPS/POPS... MCB 56 73 62 75 / 30 20 30 80 BTR 59 76 64 78 / 20 20 30 70 ASD 60 78 64 78 / 20 20 20 80 MSY 62 78 65 79 / 40 30 20 80 GPT 61 74 63 75 / 30 20 20 80 PQL 60 77 63 76 / 30 20 20 80 && .LIX WATCHES/WARNINGS/ADVISORIES... LA...None. GM...None. MS...None. GM...None. && $$
Area Forecast Discussion
National Weather Service Newport/Morehead City NC
1025 PM EST Fri Mar 1 2019 .SYNOPSIS... A warm front will move over portions of the southern coast this evening followed by a cold front late tonight. A strong low pressure system will affect the area late Sunday into Monday. Another low will develop well offshore could produce some light precipitation along the coast late Tuesday. Cold high pressure will build over the area Wednesday and Thursday. A low pressure system is expected to impact the area late next week. && .NEAR TERM /OVERNIGHT/... As of 1005 PM Fri...Minor adjustments for the ongoing forecast, mainly to account for trends in precip over Eastern NC this evening. Wind forecast remains the trickiest part, and made significant adjustments with the warm front now expected to remain more for southern coastal portions, with northerly winds for northern areas shifting west-northwesterly by 7-8Z. Used a blend of latest HRRR and NBM which seem to both have a good handle on current wind field and predicted low pressure passage followed by cold front late. The back edge of the precip is located roughly along I-95 corridor, quickly moving east toward the coast. These showers were associated with a low amplitude shortwave which is forecast to move through the area tonight. The surface reflection of this system is shifting east through the area this evening with a weak surface low now just off Cape Hatteras. The low will help push a cold front through the region late tonight. Widespread showers are expected to taper off from west to east after midnight with minimal coverage of precipitation expected after 8Z. There is enough lift/elevated instability for a couple of lightning flashes and have included a mention of thunder in the forecast. Rainfall amounts of .25-.75" with isolated amounts around an inch are expected. Temperatures along the immediate coast will be mild this evening in the 50s, with temps in the coastal plain- northern Outer Banks in mid the 40s. After the cold frontal passage temps will drop into the low to mid 40s across most of the area with upper 40s/lower 50s coast as CAA develops behind the front. && .SHORT TERM /SATURDAY/... As of 350 PM Fri...The models are indicating an area of enhanced moisture behind the front Sat morning which could result in a few light showers, then drier air will move in for the afternoon as weak high pressure builds over the area. Highs will range from the low 60s SW zones to the low 50s northern Outer Banks. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... As of 330 PM Fri...Unsettled conditions will persist through early Monday, then drier but much cooler weather is expected through late next week. Saturday Night through Monday...Strengthening surface low pressure will move across the NC Piedmont dragging a strong Canadian cold front toward the area Sunday and offshore by early Monday. Deep moisture will be drawn northeast from the Gulf of Mexico with precipitable water values peaking around 1.5" over the area Sun night. A warm front will lift north across the area Sunday with precip chances increasing through the day, but the best forcing/precip chances comes Sunday night with frontal forcing and strong upper level jet dynamics. We will be in a high shear/low CAPE environment with weak instability that could bring an isolated tstm late Sun afternoon and evening. The cold front will push across the area late Sunday night and early Monday morning with CAA ramping up through the day Monday. Highs Sun are forecast in the upper 50s to mid 60s and cooler low to upper 50s Mon. Continue to show a non-diurnal temp curve for Sunday night as it will likely remain fairly warm ahead of the cold front. Tuesday through Friday...Cold high pressure builds into the region through the middle of next week bringing generally dry and cold . Model runs continue to trend drier for Tuesday and Tuesday night with the low tracking further offshore and the GFS is the only model showing light QPF across the region, and mainly near the coast. Also, GFS sounding profiles suggest temps are a bit too warm for P-type concerns along the coast, so have removed mention of snow in the forecast. Cold high pressure will then build over the area Wed and Thu with upper troughing forecast to develop over the eastern US. High pressure moves offshore Thu night with another storm system is progged to impact the area late next week. There are some timing differences among the models so have limited PoPs to slt chc to low chc at this time. Highs Tue expected to be in the mid 40s to lower 50s, then much cooler Wed and Thu with highs in the upper 30s to lower 40s Wed and 45 to 50 Thu. Overnight lows dropping into the mid 20s to low 30s. Continued warming Fri with increasing southerly flow ahead of the front with high expected in the mid to upper 50s. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... Short Term /through Saturday/... As of 555 PM Fri...Widespread sub VFR conditions are expected this evening in visibility and ceiling as frequent showers move across the TAF sites in advance of a cold front. The showers are forecast to end by midnight but IFR ceilings are forecast to persist into early Sat morning as the low levels remain saturated. High pressure building over the area Sat afternoon will result in prevailing VFR conditions as drier air overspreads the area. Long Term /Saturday night through Wednesday/... As of 4 PM Fri ...VFR conditions expected Sat night into Sunday, but deep moisture returns to the region later Sunday into early Monday with widespread sub-VFR conditions likely with a low pressure system tracking across the area. A cold front will push across the area Monday morning with pred VFR conditions returning and continuing through mid-week as a much drier and colder airmass builds into the region. && .MARINE... Short Term /through Saturday/... As of 1015 PM Thu...Wind forecast remains very tricky this evening. Does not appear likely that the warm front will lift as far north as Oregon Inlet/Duck, and have adjusted wind field to indicate winds shifting from N/NE to N and eventually NW late for northern coastal areas. Main concern is for a brief period of marginal SCA winds (in gusts) and possible 6 ft seas over the outer fringes of the central waters after 11 PM/midnight. Peak conditions last about 4 hours with the highest seas/winds possible over the outer waters. Confidence remains low that these conditions will occur and will likely handle with a Marine Weather Statement shortly. Complex low pressure crossing the waters this evening and a cold frontal passage late tonight will initially produce SW flow 15-20 kt with a few higher gusts late this evening. Winds will then shift to the NW around 15 kt late tonight (after 6Z) and continue NW-N around 15 kt on Sat as high pressure builds over the waters. Seas will build to 3-5 ft tonight (outside over the aforementioned outer central waters), then subside to 2-4 ft Sat afternoon. Long Term /Saturday night through Wednesday/... As of 415 PM Fri...Relatively quiet marine conditions are expected Saturday night into Sunday morning with winds at or below 15 knots and seas around 2-4 feet. High confidence in SCA conditions (possibly Gales) late Sunday into Monday night. Strong SW winds 20-30 kt will develop Sunday night ahead of strong Canadian cold front. This will allow seas to build as high as 8-10 feet Sunday night and early Mon. Gale force wind gusts will be possible across the outer waters south of Oregon Inlet and the Pamlico Sound. This will followed by a strong CAA surge behind the front Mon with N winds of 15-25 knots with higher gusts and seas continuing rough at 5-8 feet before subsiding late Monday night. Developing low pressure is currently forecast to be far enough offshore Tue such that winds will be forecast 15 kt or less and seas 3 to 5 ft. Strong CAA develops Tue night and Wed behind the low with NW winds increasing to 15-25 kt and seas building back to 3-6 ft. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...None. MARINE...None. && $$ SYNOPSIS...MHX NEAR TERM...DAG/JME SHORT TERM...JME LONG TERM...SK/CQD AVIATION...JME/SK MARINE...DAG/JME/SK
Area Forecast Discussion
National Weather Service Mount Holly NJ
935 PM EST Fri Mar 1 2019 .SYNOPSIS... A developing coastal low will bring light rain and snow to the region through Saturday morning, with precipitation ending by Saturday afternoon. Dry weather briefly takes hold through Sunday afternoon. A larger coastal storm system will impact the mid- Atlantic Sunday night into early Monday with a mix of rain and snow. High pressure and dry weather moves in for most of the remainder of next week, but temperatures will be well below normal Tuesday through Thursday. Another storm system may threaten by the end of next week. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... 930 pm update: Precipitation is increasing quickly from southwest to northeast at this time. The precipitation is mostly rain, but may be mixing with a bit of sleet or freezing rain in far western portions of the CWA. A trend toward more wintry types will continue as the precipitation shield moves northward, as temperatures are hovering near or just below freezing in the winter weather advisory area. The latest hi-res model simulations continue to indicate the p-type axis near the southeast edge of the current advisory area. As a result, made no significant changes to the forecast at this time. Made some tweaks to PoPs through the night based on latest guidance and current radar trends; otherwise, the forecast appears to be holding for now. 600 pm update: Few changes made to the grids early this evening, but did want to make mention of the trend northwestward with the HRRR p-type axis in the most recent simulations. This places it more in line with other coarser and hi-res guidance, so do not feel the need to change the precipitation types much at this stage. I did add patchy fog this evening to the grids, based on several surface observations of visibilities a couple miles or lower in Delmarva and southern New Jersey. Previous discussion... The main feature of interest in the short term is a coastal low which is currently in the incipient stages of its development off the NC/VA coasts. This low will deepen & be kicked northeastward this evening into tonight as a shortwave approaches from the southwest...passing the area in latitude by early Saturday morning. Isentropic lift on the NW quadrant of this low combined with dynamic ascent from the aforementioned shortwave will produce widespread precipitation over the area tonight into Saturday morning. Timing: Hi-res guidance has slowed slightly with the onset of precipitation, with precipitation entering SW portions of the area around 7-8PM and reaching northern portions of the forecast area around or just after midnight. The heaviest precipitation will be with this initial surge tonight into early Saturday morning when warm advection is maximized in the 850-700 layer . Precipitation type/amount: Precipitation types will be a challenge again, however I-95/the Fall Line look like good approximations for the boundary between wintry precipitation and rain. Guidance has trended a bit colder overall with most ,except the GFS, keeping the warm nose southeast of Berks county/the Lehigh valley. This means most areas in the I-78 corridor and points north/west will recieve primarily snow with this event, with a mix more likely towards the I- 95 corridor with rain through most of Delmarva (outside of northern New Castle county perhaps) and the NJ coastal plain. In terms of the character of the mix, am leaning towards sleet but freezing rain cannot be ruled out with some minor ice accumulations, particularly over portions of SE PA and Central NJ near and just west of I-95. Forecast snow amounts generally range from 1-3 across most of the area in the snow zone, however some 4+ inch amounts may be possible particularly in the Lehigh valley/Bucks county and portions of NW NJ near the I-78/I-80 corridors. Although amounts may be marginal for headlines decided to issue an advisory for most of eastern PA/NW of the Fall Line, and parts of NJ north of and around I-78. Total precipitation amounts will trend down with distance from the Coast, with coastal NJ and Delmarva likely receiving near or over 0.5 inches of water (although this will be rain), with generally near or even under a quarter of an inch in the Poconos. There is some potential of a mix or snow extending a bit further south towards Philly metro for a time of the heavier precipitation (as the HRRR suggests) but feel it is a bit too cold so went with a ptype line more defined by the 3km NAM thermal profiles. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH 6 PM SATURDAY/... Although the heaviest precipitation will have tapered off by Saturday morning a secondary shortwave may reignite another round of lighter precipitation for a time Saturday morning. Rather than the warm advection characterizing the earlier precipitation there will be cold advection in the 850-700 layer in this period. This may reduce precipitation intensity but may also somewhat erode the warm layer aloft allowing some areas further southeast of the Friday night/early Saturday morning rain-snow line to receive some light snow at the tail end of the event. Once this feature passes by mid- morning it should be a quiet but relatively cloudy day over much of the area, outside of maybe a few showers in the Poconos associated with a moisture-starved clipping shortwave. Highs should run about 5 degrees below seasonal normals, but the increasing March sun angle should help melt some of the snowpack in areas affected by the earlier storm. && .LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/... The extended forecast starts out Saturday night with dry conditions and near normal temperatures as a ridge of surface high pressure tries to build across the region from the west. Zonal flow aloft is forecast across most of the CONUS, with a shortwave trof moving across the southern Rocky Mountains. On Sunday the shortwv trof continues eastward and induces low pressure development over the Gulf Coast states. It should be noted that this upper level feature is currently well off the West Coast so there is considerable uncertainty about its future movement and strength, and about the associated surface low and resultant weather. However, on Sunday increasing moisture and upward vertical velocity will be spreading northeast across the mid-Atlantic region. Precipitation in the form of rain and snow is expected to spread across the region Sunday afternoon and continue through much of Sunday night. As for precip-type, we are keeping with the idea of mostly rain south/east of the I-95 corridor, and mostly snow to the north/west. Max temps on Sunday are expected to be above freezing, but will likely fall below freezing north/west as the precip overspreads that area. Several inches of snow accumulation are possible overnight, especially across the Poconos, Lehigh Valley and northwest NJ. Precipitation is expected to be over by around 12Z on Monday with the deepening surface low somewhere near Cape Cod (although the GFS is somewhat slower). Strong low-level cold advection will be underway in NW flow, and max temps are forecast to be 5 to 10 degrees below normal. Beyond the late weekend/early week storm, much drier weather settles in for most of next week. Drier, but also much colder. Slow moving and robust longwave trough will take its time pushing through the East Tuesday through Thursday, likely finally pulling away towards Friday. High pressure moving in from the west should keep most of the region dry for a few days. Some typical nuisance, cold advection snow showers are possible in the higher terrain to the northwest with a couple of moisture starved shortwaves nearby. Also watching cyclogenesis potential offshore towards Tuesday night, but with the trough axis approaching that system will likely remain far offshore as it develops. Otherwise, 850mb temperatures tumble to -20C by Wednesday, impressive for March. Temperatures, both highs and lows, from Tuesday through at least Thursday look a good 10 to 20 degrees below normal, with gradual moderation possible towards Friday. Expecting some cold overnights throughout the week as generally light winds and clear skies will mean opportunities for efficient radiational cooling. Any snow cover will further enhance this potential, so gave some preference to colder solutions for the midweek period. By late next week, we will have to watch a low pressure of Pacific origin moving in from the west as the eastern trough pulls away and the overall flow through the CONUS becomes more zonal. Much too early for any details with that system, but given the cold air mass in place ahead of it there is potential for another winter weather event towards late Friday and into next weekend. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... The following discussion is for KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY and surrounding areas. Tonight through Saturday morning...Conditions expected to deteriorate to IFR from SW-NE between about 02-05Z. Snow is expected at ABE/RDG while rain or a wintry mix is possible in the I-95 corridor, with rain expected at KACY and KMIV. Possibly a short break in precip. early Saturday morning before a second round of lighter precipitation later Saturday morning. NE winds generally between 5-10 knots (slightly more towards the coast) backing to more northerly by daybreak. High confidence in IFR conditions, Moderate confidence in precipitation types,. Saturday afternoon...Conditions improving to MVFR at most terminals with no precipitation only lowered CIGS. A chance of VFR conditions developing, particularly at the southern terminals, later in the day. Winds backing from NW to light westerly through the afternoon. Moderate confidence in flight categories. OUTLOOK... Saturday night-Sunday... MVFR ceilings potentially lingering at least early Saturday night north of PHL. Gradual transition to VFR later Saturday night. VFR Sunday morning, then deteriorating to MVFR and potentially IFR from southwest to northeast late Sunday afternoon. Light WNW winds through late morning Sunday, then becoming light and variable. Sunday night-Monday... IFR or lower conditions likely in rain and snow Sunday night and early Monday morning. Snow most likely near and northwest of PHL-ILG with rain more likely southeast of there. Clearing conditions and a return to MVFR/VFR towards Monday afternoon. Monday night... VFR. WNW winds 5 to 10 kt. Tuesday-Wednesday... VFR. Westerly winds 5 to 10 kt turning WNW Tuesday night. VFR and light WNW flow should linger for Wednesday as well. && .MARINE... 600 pm update: Added lower portions of Delaware Bay to the small craft advisory, as gauges at Lewes and Cape May are approaching or meeting criteria at this time. Maximum winds should be observed through late tonight before diminishing below criteria by dawn. The advisory here goes until 6 am. Previous discussion... SCA seas have already developed over much of the Atlantic waters this afternoon and these 5+ foot seas will continue through most of the day on Saturday. Northeasterly winds will increase this evening into Saturday morning as the coastal low approaches, with gusts decreasing below 25 knots by Saturday afternoon. OUTLOOK... Saturday night through Sunday...Small Craft Advisory conditions may persist for a time Saturday night, mainly elevated seas on the Atlantic coastal waters. Otherwise, the conditions are anticipated to be below SCA criteria. Sunday night through Monday night...Small Craft Advisory conditions probable starting Sunday night as seas build, then northwest winds gust to 25-30 knots Monday. Winds and seas should diminish to below SCA levels Monday night. Tuesday-Tuesday night... Generally sub-SCA conditions. Seas 2 to 4 ft. Winds gusting 15 to 20 kt, with gusts approaching 25 kt possible late Tuesday night. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...Winter Weather Advisory until 7 AM EST Saturday for PAZ054-055- 060>062-101>106. NJ...Winter Weather Advisory until 7 AM EST Saturday for NJZ001- 007>010. DE...None. MD...None. MARINE...Small Craft Advisory until 6 PM EST Saturday for ANZ450>455. Small Craft Advisory until 6 AM EST Saturday for ANZ431. && $$ Synopsis...O`Brien Near Term...CMS/Carr Short Term...Carr Long Term...AMC/O`Brien Aviation...AMC/Carr/O`Brien Marine...AMC/CMS/Carr/O`Brien
Area Forecast Discussion
National Weather Service Reno NV
135 PM PST Fri Mar 1 2019 .SYNOPSIS... After a relatively quiet day today, the next storm will bring snow impacts to much of the region Saturday. Valley areas could be more of a rain-snow mix. Showers, mainly rain, will persist into Sunday with a break on Monday. A stronger, warmer storm is possible Tuesday into Wednesday but predictability on impacts remains below average. && .DISCUSSION... This Weekend... Still tracking our temperamental storm for Saturday into Sunday with rain-snow line elevations Saturday being the main predictability issue. Other than some gusty ridge winds, valley winds thankfully don`t look to be a problem with this storm. * Temperatures have warmed nicely this afternoon even with mostly cloudy skies as gusty SW winds kick in coupled with March sun energy. Not nearly as strong as the past few days but localized impacts possible in wind prone areas through early evening including lakes. These warm temperatures are a factor in valley precip types for late tonight into Sat AM with storm onset... * Latest round of simulations including HRRR showing warmer trend for lowest elevations. Precip types still have a chance of being all (wet) snow at RNO and other valley spots but rain or rain/snow mix is trending. Even if we`re mainly snow within more intense bursts of precip, with boundary layer temps mid to upper 30s the impacts should be low-end (or zero) below 5500`. There could be a little "sweet spot" from Lovelock-Gerlach- Susanville where temps are just below freezing allowing light snow accumulation on pavement. Changeover to mainly rain showers still expected by Sat PM for valleys. * Mountains and other areas above 5500` are pretty much all-snow through Sat AM. Heavy wet snow accumulations expected with corresponding travel impacts, but with quick speed of storm amounts are not major. Given the winter we`ve had I wonder if some will even notice this storm, but travel issues up into Virginia City and Sierra roads are likely Sat AM. Roads should improve quickly by Sat PM with increased sun energy and lighter precip rates. * Sunday is looking more interesting from a rainfall perspective. Secondary and slow moving low off coast of N Cal in latest simulations yielding a warming airmass with band of steady rains setting up from Portola-Gerlach. This could lead to some runoff issues and rises on creeks and rivers in NE Cal and NW Nev. Wouldn`t surprise to see Susan and Feather Rivers rise again. Continued on/off wet snow showers for Sierra passes - possibly a travel issue for ski traffic. Rain showers elsewhere including W Nev cities with even a couple t-storms not out of the question. -Chris Monday Onward... A quiet weather day is in store on Monday with just a light band of showers near the Nevada/Oregon border. The weather will then turn active once again as an upper low across the Pacific Northwest helps draw subtropical moisture northward and push a couple of shortwaves through the region through Thursday. The characteristics of this storm so far appear to be a multi-day event with 2 main pushes of moisture. The first is targeting Tuesday afternoon in early Wednesday morning followed by a second wave Wednesday afternoon into early Thursday. The initial warmer wave will have a weak to moderate atmospheric river moisture source associated with it but the trend has been to keep the main core of the moisture farther south. Right now the main plume is targeting anywhere from southern Mono county into southern Inyo county. This southward trend seems reasonable with colder air enhancing shortwave development on the backside of the main trough. This first wave also is tending towards being a faster moving system with easy but short duration rain spillover into western Nevada due to good isentropic ascent at mid-levels. Snow levels are generally looking to be around 6,000 feet around the Tahoe Basin and closer to 7000 feet farther south into Mono county. The second wave for Wednesday afternoon into Thursday time will drive a cold front through the region with snow levels possibly dropping to as low as 4,500-5,000 feet. Its a little early to assign snowfall totals in the Sierra as there will be variability over the next few days until the trajectory of the AR moisture comes into better focus but higher totals are looking more favorable to the south. Nonetheless, travel impacts for Sierra passes are still looking more likely Tuesday through Thursday. Periods of gusty southwest winds are likely to accompany with Wednesday looking to be more favorable with a tighter gradient in place ahead of the expected cold front. Fuentes && .AVIATION... * Gusty SW winds will persist across the region through this evening, but nothing compared to the past few days. Expect bumpy rides into RNO and other airports through tonight. Recent PIREP of moderate turbulence into RNO doesn`t surprise with an armada of space ship lenticulars overtop low level cumulus out the window. Moderate ridge winds of 30-40 kts will remain through Saturday so expected continued turbulence issues and maybe some wind shear with lighter valley winds. * Quick moving storm will impact the region primarily between 9z- 22z/Sat. Not a big storm but expecting periods of MVFR-IFR in rain and/or snow. Height of the freezing level remains the biggest unknown. Mild temperatures today will help start rain- snow lines above valley floors but periods of more intense precipitation could drive snow down to RNO,CXP at times Sat AM during the morning departure rush. Not expecting runway accumulations due to air temps in mid-upper 30s. For TVL, TRK a heavy wet sloppy snow is expected with some runway impacts. Same goes for MMH but snow won`t last as long there with wave swinging through fast. * Another weak storm will impact the region Sunday but this one is warmer with rain the dominant precip type for most airports in the region. -Chris && .REV Watches/Warnings/Advisories... NV...Winter Weather Advisory from midnight tonight to 6 PM PST Saturday NVZ002. Lake Wind Advisory until 7 PM PST this evening NVZ002. CA...Winter Weather Advisory from midnight tonight to 1 PM PST Saturday CAZ071. Winter Weather Advisory from midnight tonight to 6 PM PST Saturday CAZ072-073. Lake Wind Advisory until 7 PM PST this evening CAZ072. && $$ For more information from the National Weather Service visit... http://weather.gov/reno
Area Forecast Discussion
National Weather Service Blacksburg VA
1027 PM EST Fri Mar 1 2019 .SYNOPSIS... High pressure over the northeast states will wedge southward into the region into tonight. Weak low pressure across the Carolinas should pass to the east as well overnight allowing somewhat drier air to filter in on Saturday. A cold front will cross the area Sunday followed by a surge of Arctic air for early next week. && .NEAR TERM /THROUGH SATURDAY/... As of 1020 PM EST Friday... Short wave had moved into central Virgina and the bulk of the precipitation has moved east of Buckingham to Charlotte Counties. Isolated to scattered light rain will continue to diminish in coverage for the the rest of the night in all but the far western upslope areas. Temperatures from Bent Mountain down through the higher elevations of Floyd County and along the Blue Ridge south of Roanoke were still around freezing. Now that the precipitation is ending, will be cancelling the Winter Weather Advisory. Will highlight the potential for some freezing drizzle and freezing fog along the Parkway. MSAS analysis showed the low off the coast just starting to become deeper than the surface low over West Virginia. The low off the coast will continue to strengthen and become the primary feature overnight. Behind this surface wave a more pronounced northwest trajectory to take place as we slide between systems within fast zonal flow aloft. This should help scour out remaining low level moisture under weak cool advection but to what degree surface mixing evolves remains in question. Appears areas east of the Blue Ridge should be able to clear out per downslope and March sunshine while low clouds may linger Blue Ridge and points west until afternoon, and perhaps never clear the far western upslope areas. However expect any lingering light drizzle/freezing drizzle to fade across the northwest early on with a dry day on tap for the afternoon. Cloud exodus will also make highs tricky with potential to top 60 far south while perhaps staying in the 40s mountains where clouds linger. Therefore trended with the colder Met mos west and some of the warmer guidance east. && .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... As of 300 PM EST Friday... Zonal flow will give way to a broad upper trof settling over the eastern part of the country into the first part of next week. This will usher in much colder air as winter still lingers across the Appalachians and central mid Atlantic region. By Sunday, low pressure moving through the deep south will push warm air up and over a wedge of high pressure east of the mountains. This will gradually generate widespread precipitation across the region through Sunday afternoon. Temperature profiles look to remain on the warm side with support for liquid ptype for all but the far northern sections up near the Interstate 64 corridor where some wet snow or mixed precip may produce a light slushy accumulation. Things will then change as the low slides by to our south and then moves up the coast Sunday night and colder air starts to work in from the west. Expect ptype to change over to snow in the west with possibly a little freeing rain mixed in but precipitation further to the east looks like it will be ending before any appreciable changeover to wintry ptype is possible. The end result will be 2 to 4 inches of wet snow across western Greenbrier WV with lesser accumulations elsewhere across the Alleghany Highlands and at the higher elevations west of the Blue Ridge, along with a light glaze of freezing rain possible Sunday night into Monday morning. There is much uncertainty in these accumulations and if the trend toward a warmer solution continues amounts will be reduced. If a trend toward a colder solution develops amounts will increase, possibly by a considerable amount. With so much uncertainty will not issue a winter storm watch at this point and await later model runs to arrive at a consensus. Overall precipitation totals with this system will be fairly robust with liquid totals of 1 to 2 inches. Soil moisture continues to run well above normal so excessive runoff and some flooding may be possible once again, especially for the Dan river basin. Also, as the low drags an associated cold front along there are indications that convection may fire to our south. There is an outside chance that some thunder may be able to work its way up into portions of the NC foothills/piedmont and possibly Southside VA Sunday evening. Upslope snow showers will linger west of the Blue Ridge, mainly at the higher elevations, into Monday before tapering off through Monday afternoon. Temperatures will be below normal, then begin to nose dive as colder air surges in behind the departing low on Monday. && .LONG TERM /TUESDAY THROUGH FRIDAY/... As of 300 PM EST Friday... The broad upper trof over the eastern US will bring cold and blustery conditions to the Appalachians and central mid Atlantic region through the middle of next week. There may be some upslope snow showers around west of the Blue Ridge on Tuesday and Wednesday but a better chance of rain, mixed with some snow to the north, on Thursday as a warm front pushes into the region. Guidance has then offered a variety of solutions by the latter portion of next week as solutions have ranged from wet to dry. Ensemble clusters have a good amount of spread indicative of the uncertainty in the solutions, so confidence is low heading into Friday. The most likely evolution looks to feature a low moving through the midwest and spreading precipitation into the region on Friday and into Friday night which may be a wintry mix west of the Blue Ridge into the Alleghany Highlands. Temperatures will be well below normal for Tuesday and Wednesday, but some moderation will set in for the end of the week, though any recovery will still leave readings below normal through Friday. && .AVIATION /04Z SATURDAY THROUGH WEDNESDAY/... As of 645 PM EST Friday... Water vapor loops showed a well defined short wave just crossing into southwest Virginia. The western edge of the shield of light to moderate precipitation associated with this short wave was just crossing KROA at 00Z. Based on the current radar trends this MVFR rain will exit southern Virginia and northern North Carolina by 04Z/11PM. Scattered showers and isolated thunderstorms were behind the main area of rain. These showers will weaken as they move east over the well-established surface based wedge of cold air. Behind this wave and the rainfall ceilings and visibilities will remain IFR to LIFR with fog, stratus and drizzle. As low pressure deepens off the coast overnight and erodes the wedge surface winds will gradually come around to the west and northwest. By 15Z/10AM SPC HRRR radar showed a northwest wind all the way through the piedmont. Once this downslope wind develops, ceilings and visibilities will improve in the Virginia and North Carolina foothills and piedmont. Low level moisture will remain banked up against the central Appalachians and ceilings will remain sub- VFR for much of the day at KBLF/KLWB. Above average confidence in the the timing of the precipitation. Average confidence on the category and timing of the ceilings. EXTENDED AVIATION DISCUSSION... Weak cold front crosses the region by later Sunday allowing low pressure to ride up the boundary resulting in widespread rain and western mountain snow including MVFR/IFR conditions Sunday into Sunday night. Deeper moisture exits by Monday with lingering MVFR possible mountains under lingering lower cigs and spotty snow showers. Drier and much colder air on gusty northwest winds will result in improving conditions, especially east of the Blue Ridge Monday afternoon. Will see widespread VFR across the region Tuesday and Wednesday as very dry air associated with Arctic high pressure arrives from the west. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...None. NC...None. WV...None. && $$ SYNOPSIS...JH NEAR TERM...AMS/JH SHORT TERM...MBS LONG TERM...MBS AVIATION...AMS/JH
Area Forecast Discussion
National Weather Service San Diego CA
750 PM PST Fri Mar 1 2019 .SYNOPSIS... A Pacific storm system will move rapidly across California on Saturday, bringing more widespread rainfall and high snow levels Saturday through Sunday morning. Strong and gusty westerly winds will accompany the system over the mountains and deserts on Saturday and Saturday night. Clouds will slowly break on Monday with warmer days on tap for both Monday and Tuesday. Another storm system will take aim at central California by Tuesday. Scattered, light showers could break out this far south, but rain looks more likely for Wednesday or Thursday. Cool and showery weather may persist into next weekend. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... High clouds were streaming east over SoCal this evening. The 00Z Miramar sounding showed a gradual increase in westerly winds and moisture below 25K FT, but little in the way of instability. There still was little in the way of sfc pressure gradient trends, but they remained weak to moderate onshore. Peak westerly wind gusts were still in that 30-40 MPH range at 7 PM PST. The latest Water Vapor imagery over the EastPac shows the upper low tracking rapidly east toward the Central Coast this evening. Lightning was still a prominent feature with this system north of 32N latitude. Indications are that this activity will remain to the north of the forecast area. The latest NAM12 and HRRR operational runs are on track, bringing precip across SW CA area early Sat morning. Given the high PW values forecast, at least moderate precip rates can be expected for a time Sat morning. Southwest to west winds should become quite gusty as well on Saturday, prompting a Wind Advisory for the mts/deserts. Please see LAXNPWSGX or our web page for details. No forecast changes this evening. From previous discussion... Although good moisture is advecting into the system over the Eastern Pacific (Sat estimate PWATs are near 1.5" in advance of the trough and nearly 200% of normal), the trough is on the decaying side and will not be able to quite tap into all that subtropical moisture available. Storm total rainfall through Sunday is expected to be 0.25-1.00" for the coast and valleys, and 1-2" over the mountains, with isolated amounts in the favored upslope sections of the San Bernardino Mountains up to 2.50" through Sunday. Cold air with the Pacific storm is also decreasing and the potential for thunderstorms has gone down over the last couple of model runs. As a result, @SPC has pushed the mention of general thunderstorms to the north of our region, and therefore we have removed mention of thunderstorms for Saturday, which previously was over the Inland Empire and OC for Saturday. With the best colder temperatures to the north, snow levels will generally be very high with the Pacific storm Saturday through Saturday night, initially above 8000 feet, then lowering to around 7000 feet by late Saturday afternoon. On Sunday, occasional mainly light showers will be pesky given the remnant moisture profile and we continue to mention at least a chance of showers in the forecast, especially for the mountains, through Sunday afternoon. Looking ahead to next week... Another Pacific storm system will take aim at Central CA on Tuesday. There is still considerable spread in the operational model runs with regard to the onset and amount of any precip that may fall. Similar to the storm system this weekend, it will have a good tap on Pacific moisture, but the forcing and trajectory favor areas from LA County northward to get the brunt of the precip. At least modest rainfall amounts with high snow levels are possible here, either Wednesday or Thursday, with the greatest amounts north of San Diego County. Moist conditions and possible showers could linger into next weekend. && .AVIATION... 020400Z...Coast/Valleys...Patchy stratus with bases 1000-1500 ft MSL will occur tonight near the coast with local vis 3-5 miles in fog. Widespread higher clouds will gradually lower to 3000-5000 ft MSL by 11Z Sat with rain developing 11Z-14Z Sat and continuing most of the day. BKN-OVC cloud bases will be 800-2500 ft MSL with areas of vis 3-5 miles in rain, locally lower, with areas of terrain obscurations. Mtns/Deserts...Widespread clouds above 15000 ft MSL will gradually lower to 3000-5000 ft MSL by 12Z Sat with mountain obscurations developing. Rain will spread over the mountains and into parts of the deserts after 12Z Sat with widespread mountain obscurations. Areas of west/southwest winds 20-30 knots with gusts 40-50 knots will occur in the mountains starting 09Z Saturday. && .MARINE... Despite the storm system moving through this weekend, winds will mostly remain 20 knots or less, with strongest winds from the south Saturday. Similar winds are expected with the following storm system around next Wednesday. Otherwise, no hazardous marine weather is expected through Wednesday. && .SKYWARN... Skywarn activation is not requested. However weather spotters are encouraged to report significant weather conditions. && .SGX WATCHES/WARNINGS/ADVISORIES... CA...Wind Advisory from 10 AM Saturday to midnight PST Saturday night for Apple and Lucerne Valleys-Coachella Valley-Riverside County Mountains-San Bernardino County Mountains-San Diego County Deserts-San Diego County Mountains-San Gorgonio Pass Near Banning. PZ...NONE. && $$ PUBLIC...10/Brotherton OUTLOOK...10 AVIATION/MARINE...Maxwell