Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 04/02/18

Area Forecast Discussion
National Weather Service Boston/Norton MA
1015 PM EDT Sun Apr 1 2018 .SYNOPSIS... Weak high pressure builds over the region with cooler drier air tonight. Low pressure moves offshore along the Mid-Atlantic coast and heads east, brushing Southern New England with some snow Monday morning. Unsettled weather returns Tuesday afternoon into Wednesday with rain at times along with milder temperatures, then blustery and colder weather follows Thursday. More unsettled weather is possible sometime Friday into next weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... 10 pm update... Forecast challenges remain even within 12 to 18 hours. Precipitation amounts coupled with intensity, snow ratios, surface temperatures. All factors to potential snowfall amounts, hazards. Certain, W-E sweeping open-wave H5 vortmax / trof axis, beneath RRQ of a cyclonic H3 jet axis yields Mid-Atlantic cyclogenesis. Advance SW 290-310K isentropic flow against a H925-7 cold airmass in place, S-N thermal packing / frontogenesis, should yield W-E snow banding, especially around H85, towards Monday morning through midday. Can`t rule out snow ratios around 15:1 per H925-85 -4 to -6C temperatures. Fluffier snow, efficient accumulation, more so if 2m temperatures are at or below freezing. Ageostrophic flow, N/E, should maintain lower surface dewpoints 20s to teens S to N, drier boundary-layer airmass, potentially aiding lower 2m temperatures with wet-bulbing. Uncertain is frontogenetical extent N into S New England, whether it remains mainly along or offshore the immediate S-coast. Omega within snow-growth regions under scrutiny, upwards of 25 microbars / second yet to what breadth and extent N? This lends to lower confidence on exact snowfall intensity into S New England. However, given the cold airmass, even if light, should accumulate early Monday morning. SREF continues to signal 1"/hr snowfall rates into SW New England by Monday morning, diminishing while peeling offshore towards midday. Echoing the prior forecaster, such rates would overcome any marginal 2m temperatures yielding efficient accumulation on all surfaces. Close eye on HRRR / RAP / HREF trends. Continued confidence advisory level snows across S-coastal New England. Will hold with the present forecast, headlines. Can`t rule out Outer Cape / Martha`s Vineyard advisory-level snows but perhaps not widespread per warmer ocean influence. Greatest concern for the Monday morning commute across the Hartford- Springfield metro areas. Low visibility along with accumulating snow- fall will make for hazardous travel conditions. Snow moving in around 9 am for areas E around the Providence-metro, perhaps less impact to the commute which should be concluding, however expect hazardous travel conditions with light to moderate snow to spread E. As to the near term, weak high pressure settling in, winds on a down- ward trend. High clouds settling in, window of decoupling boundary layer / radiational cooling is closing. Lows down into the 20s to low 30s as snow settles in by morning. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Daybreak Monday... * Accumulating snowfall could impact the morning commute Open wave and associated surface low pressure system will pass S of the region Monday morning. At the onset of precip, appears to be a strong temp/dewpoint spread. However bufkit and model cross- sections suggest that strong omega in the snow growth region will help overcome this spread resulting in temperatures to wet-bulb. Several hi-res guidance members including the HREF, HRRR and SREF show good probability in an inch an hour snowfall rates as the system passes. These snowfall rates will help overcome and marginal surface temps resulting in accumulations not just on grassy surfaces but on area roadways as well. One thing to note, appears that the best F-gen is still just offshore, so if this low scoots a bit northward than advisories will need to be expanded. Timing of this system appears to be around 6-8 am. Heaviest snowfall closest to the 8am hour which could lead to some impact to the later half of the morning commute, esp for the I-195 corridor. This is a quick moving wave due to lack of any blocking across the Atlantic, thus expect snow to end from west to east between 10 am and 1 pm. Overall updated this portion of the forecast towards a GFS/EC/RGEM blend resulting in 1-2 inches of snowfall south of the Mass Pike. 2-4 inches of snowfall across the southern half of RI and into MA south coast. Still some uncertainty on how much will accumulate across the Cape and the Islands. Snow will be moving in a bit slower in that region and with high sun angle and warming temps, may limit how much would actually accumulate. Anticipate most of the snowfall to occur across the grassy surface and elevated roadways. Locations along the south coast could see area roadways accumulate snowfall. No changes to the headlines at this time. Monday afternoon and evening... Weak high pressure re-builds over our region. This will bring clearing skies and light wind. Fair skies should allow temperatures to warm near 40 during the day and then to drop below freezing in most areas at night. Increasing mid and high level moisture moves in after midnight. Expect increasing clouds at that time. && .LONG TERM /TUESDAY THROUGH SUNDAY/... Highlights... * Moderate temperatures and active weather Tuesday into Wednesday * Blustery and cooler for Thursday * Active weather returns for the end of the week Overview... Active weather pattern remains for southern New England with just a few breaks here or there. Broad upper level trough continues to be anchored with upper level low over Hudson Bay. Strong Pac NW wave will get captures in the broad cyclonic trough and push towards the Great Lakes and into northern New England by mid-week. Expect a few bouts of rainfall with this low as PWAT values are nearing 2-3 +STD with increasing LLJ. As the system`s cold front moves offshore, blustery and cooler temps will usher into the region on Thursday. Ridging for the West will allow for Arctic shortwave to dive into the trough and rotate towards southern New England by Friday. Depending on timing and strength, this system could bring snow/rain to the area. Reinforcing arctic airmass will be in place as southern stream wave approaches from the Ohio River Valley by next weekend. Details... Tuesday into Wednesday...Moderate confidence. Mid-level ridge and surface high pressure to start the period will exit offshore as low pressure system approaches from the west. Showers will begin to move into the region by the late morning/early afternoon as warm front approaches from the south and higher theta-e values advect into the region. This overrunning precip event is not expect to amount to to much. Depending on the timing, could see some wet flakes or sleet mixed in at the onset, but overall p-type will be in the form of rain. Warm front will push through Tuesday night allowing for temps aloft to quickly warm. Trended the forecast towards a mild night and used a non-diurnal trend. Cannot rule out the potential for dense fog, esp across the south coast, as higher dewpoint air advects over the cooler ocean. Pretty strong LLJ will strengthen overnight but lapse rate suggest that mixing will be limited. Thus with this type of inversion the potential for fog to move into the interior is possible. Southern New England will be in the warm sector by Wednesday morning. With a break in the precip during the morning, and perhaps some breaks in the clouds could help increase surface temps into the low to mid 60s. Since temps will warm into the 60s, lapse rates could steepen enough to allow for mixing of the 40-50 kt LLJ down to the surface. If this occurs than a wind adv will be needed. Confidence is higher with mixing behind the front, but LLJ is weaker. As the cold front sweeps through, heavy rainfall is possible thanks to strong LLJ and high PWAT airmass. However, the better dynamics will be closer to the surface low which is pulling away from the region so not expecting any flooding concerns at this time. Overall is appears to be a soggy Wednesday afternoon as rainfall quickly moves through the region. Thursday and Friday...Moderate confidence. Behind the cold front, anomolous cold airmass will filter back into the region. This will knock temps back to below average for this time of year, esp on Thursday. Blustery conditions are expected thanks to strong northwest flow. Another shot of rain and snow will usher into the region on Friday as a quick moving wave swings through. Still some uncertainty on exact location and timing as the EC is more progressive compared to the GFS. The weekend...Low confidence. Reinforcing arctic airmass will be in place as southern stream wave approaches from the Ohio River Valley by next weekend. This system could bring another bout of rain or snow. Something to watch in the coming week. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday Night/...High confidence. Tonight... VFR. Mid-high level CIGs thickening, lowering towards early morning Monday. Light north winds turning from the northeast. Monday... MVFR-IFR cigs move across CT-RI-SE Mass during the morning. Vsbys lower to IFR in snow with brief LIFR vsbys possible. Farther north across Springfield/Worcester/Boston a period of MVFR cigs/vsbys is possible in snow during the morning. Conditions should improve to VFR in clearing during the afternoon. Airports along the immediate south coast have the best potential for snow accumulation. Monday afternoon... VFR. Fair weather with increasing mid and high clouds after midnight. KBOS Terminal...High confidence in TAF through 5 AM, then moderate confidence. Most snow is expected to pass south of the airport, but it is possible for a few hours of lower conditions Monday morning which could impact the morning rush. KBDL Terminal...High confidence in TAF through 5 AM, then moderate confidence Monday morning. A brief period of mod SN is possible which could lower conditions. Outlook /Tuesday through Friday/...Moderate Confidence. Wednesday: Mainly VFR, with areas MVFR possible. Windy with gusts to 35 kt. Chance RA, isolated TSRA. Wednesday Night: VFR. Windy with local gusts to 30 kt. Thursday: VFR. Breezy. Thursday Night: VFR. Breezy. Slight chance SHSN. Friday: Windy with gusts to 35 kt. Chance SHRA. Friday Night through Saturday: Breezy. Chance SHRA, slight chance SHSN. && .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. Short Term /through Monday Night/...High confidence. Tonight... Gusty west winds through the evening with gusts to 25 knots. This wind will diminish 8-11 PM with light winds overnight. Lingering 5 foot seas on the outer waters through midnight, then less than 5 feet overnight. Small Craft Advisory lingers for the first part of the night. Monday... Snow/Rain spreads over the southern waters early morning and possibly reaching the Merrimack River. Precipitation then tapers off midday or early afternoon. Vsbys 1 to 3 miles in snow around the South Coast during the morning. Winds will be less than 20 knots and seas less than 5 feet. Monday night... Winds below 20 knots. Seas less than 5 feet. Outlook /Tuesday through Friday/...Moderate Confidence. Wednesday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 13 ft. Rain likely, isolated thunderstorms. Wednesday Night: Moderate risk for Small Craft Advisory winds with gusts up to 25 kt. Areas of rough seas. Thursday through Thursday Night: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Local rough seas. Friday: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Rough seas up to 12 ft. Chance of rain showers. Friday Night: Moderate risk for Small Craft Advisory winds with gusts up to 30 kt. Areas of rough seas. Slight chance of rain showers. Saturday: Winds less than 25 kt. Seas locally approaching 5 ft. Chance of rain showers. && .EQUIPMENT... Due to our move to the new forecast office in Norton, MA, we are still trying to resolve some communication issues. The following NOAA Weather Radio transmitters are back on the air: Somers, CT transmitter........WXJ41.....162.475 MHz Paxton, MA transmitter........WXL93.....162.550 MHz Johnston, RI transmitter......WXJ39.....162.400 MHz Gloucester, MA transmitter....WNG574....162.425 MHz However, the following NOAA Weather Radio transmitters are not yet on the air: Blue Hill, MA transmitter.....KHB35.....162.475 MHz Hyannis, MA transmitter.......KEC73.....162.550 MHz && .BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...Winter Weather Advisory from 2 AM to 2 PM EDT Monday for MAZ020-021. RI...Winter Weather Advisory from 2 AM to 2 PM EDT Monday for RIZ006>008. MARINE...Small Craft Advisory until 11 PM EDT this evening for ANZ230>237-250-251-254. Small Craft Advisory until 2 AM EDT Monday for ANZ255-256. && $$ SYNOPSIS...WTB/Dunten NEAR TERM...WTB/Dunten/Sipprell SHORT TERM...WTB LONG TERM...Dunten AVIATION...WTB/Dunten/Sipprell MARINE...WTB/Dunten EQUIPMENT...WFO BOX Staff
Area Forecast Discussion
National Weather Service Columbia SC
1038 PM EDT Sun Apr 1 2018 .SYNOPSIS... High pressure over the Southeastern States will weaken Tuesday. Above normal temperatures and dry weather are expected through Tuesday. A cold front will cross the area Wednesday, bringing a chance for showers and possible thunderstorms. Dry high pressure will take hold Thursday and Friday. Another cold front may affect the region next weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Forecast continues to be on track will little change needed for this mid evening update. The thin cirrus that has been overhead this afternoon and early evening is moving away from the area. There are a few patches of mid clouds in the upstate that might try to brush through Lancaster county in the next few hours, so the sky grids are a bit higher up there, but still not enough to worry about any ceilings that might effect overnight temperatures. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... Surface high pressure over the Southeastern States will gradually weaken and slip off the south Atlantic coast Tuesday. Above normal temperatures and generally dry weather is forecast. A Westerly 500 mb flow Monday will back to more southwesterly Monday night and Tuesday and heights will rise in response to digging shortwave energy over the middle part of the country and associated cold front. Warming 850 mb temperatures and deep mixing along with plenty of sunshine will allow temperatures to warm well into the 80s both Monday and Tuesday. Several runs of the MAV MOS indicated highs in the upper 80s Tuesday. Overnight lows will be in the mid and upper 50s Monday night then in the lower 60s Tuesday night. Low-level moisture will continue to increase across the region with deep southwesterly flow and precipitable water values increasing to around an inch by Tuesday afternoon and up to 1.25 of an inch Tuesday night. Since upper-level forcing remains to the west of the forecast area along with an approaching cold front, will continue chance pops in the western Midlands and upper CSRA with slight chance pops elsewhere late Tuesday night. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... The upper-level flow pattern will become more amplified during the extended forecast period with a couple of systems that will impact the forecast area bringing chances of showers and thunderstorms. An upper-level trough and associated low pressure system will lift into New England Wednesday pushing a cold front through the forecast area. Still some timing differences among the operational GFS/ECMWF/CMC but the front will cross sometime during the day Wednesday bringing a period of showers and possibly some thunderstorms depending on the timing and available instability. Severe weather does not appear likely at this time. Will continue to carry likely pops Wednesday with pops diminishing by late afternoon Wednesday as the front moves into the Coastal Plain. Cool high pressure will build into the region from the west with clearing skies by the evening. Rainfall amounts generally expected in the quarter to half inch. Thursday and Friday look to be dry and much cooler behind the front with surface high pressure settling over the forecast area. The next weather system will impact the region Saturday into Sunday as another shortwave trough drops into the Plains and shifts eastward. Temperatures through this period will be near to above normal Wednesday followed by below normal temperatures Thursday and near to slightly below normal Friday through Sunday. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Expect mainly VFR conditions during the TAF period. There may be a period of MVFR or IFR during the early morning hours. High pressure has shifted off the Southeast Coast. Some increase in low-level moisture has occurred. This moisture combined with nocturnal cooling may result in stratus and fog toward dawn. The SREF guidance indicated greater chances of restrictions in the southeast section closer to higher moisture affecting the AGS, DNL, and OGB terminals. Most of the NAM and GFS MOS plus HRRR guidance maintained VFR conditions but based on the period of fog the previous morning at AGS we leaned toward the more pessimistic guidance and forecasted a period of MVFR fog at AGS, DNL, and OGB. Believe heating and mixing will bring improvement after 14z. Followed the GFS and NAM MOS for the wind forecast with wind light tonight and mainly southwest near 10 knots Monday. The NAM Bufkit momentum transfer tool and GFS LAMP suggested gusts around 16 knots Monday afternoon. EXTENDED AVIATION OUTLOOK...Late night and early morning stratus and fog is possible through Wednesday. Showers and possible thunderstorms Wednesday. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$ SYNOPSIS...99 NEAR TERM...99 SHORT TERM...99 LONG TERM...99 AVIATION...99
Area Forecast Discussion
National Weather Service Charleston SC
949 PM EDT Sun Apr 1 2018 .SYNOPSIS... High pressure will prevail through Tuesday. A cold front will move through late Wednesday, followed by high pressure into Saturday. Another cold front will impact the area next Sunday. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Surface high pressure building over the Atlantic is forecast to extend west overnight with a tranquil weather pattern in place for the region. The main forecast challenge overnight continues to be fog and stratus development. The setup is quite good with respect to dry air and light winds atop fairly moist near-surface layers. The latest HRRR surface condensation pressure deficit progs along with LAMP/SREF data suggests the better potential for low stratus may end up to the east of I-95 in SC. We made some adjustments to fog potential in our grids but the message is generally the same, patchy to areas of fog nearing daybreak. No significant changes to lows in the mid 50s most areas with light to calm winds. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... Monday: Dry and unseasonably warm conditions will again prevail, with a zonal flow aloft, while Atlantic high pressure stretching across the local area at the surface. A cold front extending westward from a Clipper-type low off the Delmarva will struggle to make much headway southward, blocked by the high and also aligned parallel to the westerly flow aloft. A deep offshore flow, H8 temps that are as warm as 13-14C (or near the 90th percentile for early April), deep mixing and plenty of insolation will boost max temps into the lower or middle 80s inland from the Intra-Coastal Waterway (ICW). With sea breeze circulations across lower 60 water temps, locations at or near the shoreline will be significantly cooler. Monday night: Little change in the overall synoptic scenario, with high pressure at the surface and a zonal flow persisting aloft. Weak warm advection within a SW synoptic flow won`t allow for temps to get any cooler than 58-62F, which is far above climo. There is at least some potential for fog to develop, as shown by the SREF probabilities of 60% or greater. But geostrophic winds are a little too high around 15 kt, and condensation pressure deficits are no lower than 10-20 mb. So for now we have nothing more than "patchy" wording, and some of that could actually be as sea fog. If it does, coverage could be greater and dense fog would be a concern. Tuesday: A deepening short wave in the central states will cause some increase in heights atop the SE, while a frontal system tracks NE through the upper Midwest and the Atlantic ridging holds firm locally. There is some increase in low level moisture within a deepening S-SW flow, and that along with a little bit of instability and a weaker subsidence cap might allow for a couple of showers to initiate on the sea breeze, mainly in GA. But since we still have quite a bit of dry air above 850 mb, and omega fields are limited, we have maintained a rainfree forecast with PoP no higher than 14%. It`ll be another exceptionally warm day with H8 temps again around 13-14C, leading to highs similar to Monday. Places closer to the coast and on the beaches could actually be a tad cooler than Monday, with an earlier start to the sea breeze. If there is any sea fog it would shift into the Atlantic by mid to late morning. Wednesday: The mid and upper flow becomes more amplified, as a deep surface low passing into eastern Canada, while it`s associated short wave pushes through the Great Lakes and Ohio Valley toward the NE states. A trailing cold front from the low will approach the NW, before passing into the ocean late. Moisture will continue to increase, both of amount and in depth, with PWat reaching near or greater than 1.5 inches. This along with modest QG forcing with height falls aloft, and upper difluence with RRQ of the upper jet nearby to our NW, will support high probabilities of light to moderate showers. Since there are sill some timing differences between the various model solutions, we won`t go any higher than 70% at this time. However, categorical PoP`s are likely as the event draws closer. Despite the elevated PWat, given the progressive nature of the convection, we have presently have up to about 1/4 inch of QPF. We continue to mention slight chance of t-storms in the forecast with some instability, shear and adequate lapse rates. But the overall thermodynamics are rather insignificant, so the risk of severe weather is extremely low. Temps are highly dependent on the timing of convection, but since we`re starting the day some 12-16F warmer than average, max temps should again be well above normal. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... High pressure will prevail, bringing dry conditions. Another cold front should impact the area by next Sunday. Coolest conditions will be on Thursday, before another warming trend develops late in the week into next weekend. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... VFR until later tonight when fog and stratus look to pose a risk limiting flight restrictions. Since coastal GA appears to have a slightly higher potential for IFR conditions, we maintained persistance with the 00Z TAF cycle. Latest NAM forecast soundings show favorable fog stabilities indices progged in the single digits at KSAV and teens at at KCHS later tonight. Southwest synoptic flow is not all that favorable, since advection fog/stratus is unlikely. VFR conditions will return by late morning on Monday. Extended Aviation Outlook: Flight restrictions are possible in fog/stratus late Monday night into early Tuesday morning, then again with SHRA and possible TSRA in association with a cold front on Wednesday. && .MARINE... Tonight: High pressure centered over the western Atlantic will allow winds to veer to the south overnight but no significant winds/seas are expected. Could see some fog impact areas near the coast late. Monday through Tuesday: Sub-tropical high pressure will remain in control early this week, and even with sea breeze influences, winds and seas will remain below any advisory conditions. Wednesday and Thursday: A cold front will approach from the NW during mid week, passing through the waters by late Wednesday, followed by continental high pressure behind the front into Thursday. Warm advection will limit the amount of mixing on Wednesday in advance of the front, so even though winds and seas will climb, conditions still look just shy of any Small Craft Advisory levels. Instead, large isallobaric pressure rises and cold advection behind the front allows for the better chance of obtaining advisories Wednesday night into Thursday, on at least parts of the marine area. Mariners can expect showers and at least a few stronger t-storms to occur in association with the cold front. Friday and Saturday: Much better conditions on Friday with Atlantic high pressure directly atop the waters, before conditions deteriorate again next Saturday ahead of a cold front. Sea Fog: There seems to be about a 12-15 hour period where sea fog is possible from late Monday evening into midday Tuesday, with the most favorable wind fields and dew points to occur during this time. We continue to mention "patchy" sea fog in the forecast and in the Hazardous Weather Outlook. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE...
National Weather Service Jackson KY
1105 PM EDT Sun Apr 1 2018 .UPDATE... Issued at 1105 PM EDT SUN APR 1 2018 Did a quick update to mainly to fine tune the PoPs in the south along with adding a bit more QPF down there. Also touched up the T and Td grids per the latest obs and trends. These have been sent to the NDFD and web servers. UPDATE Issued at 850 PM EDT SUN APR 1 2018 00z sfc analysis shows an area of low pressure riding northeast along a stalled frontal boundary that is bisecting the JKL CWA. This is bringing with it a healthy slug of moisture with over- running rains quickly spreading into eastern Kentucky from the west. Winds across the area are generally light and from the northeast under overcast skies. There is quite a temperature gradient across the JKL CWA running from the mid 40s north to the low 60s in the far southeast. Dewpoints vary similarly from the mid 30s north to the upper 40s and low 50s south. As the pcpn moves in, wetbulbing will lower temperatures significantly across the area. However, they will remain enough above freezing (and with warmer air riding in aloft) to preclude snow despite temperatures likely to fall into the mid 30s by dawn north of I-64. Cannot rule out some brief partially melted snowflakes mixing with the rain north late tonight, but this will be immaterial should it even occur. Otherwise, the forecast is on track with just some adjustments to PoPs and Wx made through the night per the latest HRRR and NAM12. Also added in the latest obs and trends to the T and Td grids. Look for an updated set of zones shortly. The grids have been sent to the NDFD and web servers. && .SHORT TERM...(This evening through Monday night) Issued at 349 PM EDT SUN APR 1 2018 Current conditions across the area feature a boundary draped across eastern Kentucky with extensive cloud cover associated with a passing wave along the boundary. Much of the precip from this morning has exited off to the southeast. To the west, another system takes aim at the region. This wave will quickly push east along the boundary bringing a good shot of rainfall across mainly northern Kentucky. In fact, models suggest a good 0.50 to 0.75 inches of rainfall to the Bluegrass region tonight. Surface temps for this will be too warm for any snowfall so all rain will be anticipated for tonight. In fact, PWAT values will be around an inch which is still a bit wet. Just like the previous wave, this feature will quickly pass to the east as the boundary once again pushes to the south. This will again divide the CWA with cooler temps to the north and warmer temps to the south of the boundary. By the day on Monday, a surface low will deepen out west and will begin to push east as southerly flow increases in strength. This will develop a warm front that will lift north Monday evening and into Monday night. Instability on the increase will allow for the potential of a few thunderstorms. There is some uncertainty here as the instability will be a bit elevated. Thus will go for a slight chance of thunder and mainly in the Bluegrass for late Monday night. If this instability is realized better then the thunder chances will be more prevalent. Will still mention this in the HWO. Still a tricky temperature forecast seems to be on tap with a boundary that will waiver across the area for tonight and tomorrow with a couple passing waves that will cause the gradient to shift from north to south and then shift north again Monday night with the development of the warm front. .LONG TERM...(Tuesday through Sunday) Issued at 329 PM EDT SUN APR 1 2018 The models are in fairly good agreement at the start of the forecast period, but begin to diverge as we move into next weekend. Outside of Tuesday the long term portion of the forecast will feature below normal temperatures, with several systems poised to bring repeated rounds of precipitation to the area. The forecast period begins with a short wave mid level trough moving east from the plains and a surface low in eastern KS or western MO set to move into the Great Lakes Tuesday night. As the surface low moves northeast a cold front will push southeast, and move across our area Wednesday night. A significant warm up should occur ahead of the cold front on Tuesday, with high temperatures in the 70s. With a tightening pressure gradient and some mixing Tuesday afternoon wind gusts of 30 mph or more will be possible, especially in the Lake Cumberland area. Best dynamics still remain to our west, but there will be enough shear and instability, at least across the western part of the area that any thunderstorms that develop ahead or along the cold front could be strong late Tuesday afternoon into Tuesday evening. The best chance for strong storms remains in the western part of the forecast area. After the frontal passage much cooler air will once again spread into the area, with high temperatures on Wednesday 10 to 15 degrees below normal. High pressure will build into the area Wednesday night and set the stage for clearing skies, light winds, with frost and sub freezing temperatures becoming more likely. Will continue to highlight the frost threat in the HWO for Wednesday night into Thursday morning. With the high shifting east and ample sunshine on Thursday temperatures will be several degrees warmer than Wednesday, but still remain below normal. A second cold front will move across the area late in the week or next weekend, with the GFS showing the front moving across our region Thursday night into Friday, but the ECMWF showing the front moving across our area about 24 hours later. Needless to say confidence in the latter part of the forecast is low. While there are timing differences the main theme is that there will be another precipitation chance late in the week and into the weekend, and a reinforcing shot of cold air for next weekend. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) ISSUED AT 820 PM EDT SUN APR 1 2018 With moisture and pcpn riding east northeast into the area along a boundary currently lying across eastern Kentucky, VFR conditions will fall to MVFR and then quickly to IFR from west to east. Conditions will also deteriorate with respect to visibility through the bulk of the night in the rain before backing off to VCSH around dawn. Look for some improvement in cigs later Monday afternoon. Winds are expected to remain rather light through the period. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...SHALLENBERGER LONG TERM...SBH AVIATION...GREIF
Area Forecast Discussion
National Weather Service Memphis TN
855 PM CDT Sun Apr 1 2018 .DISCUSSION...01Z Surface analysis this evening places a cold front between Savannah, TN back through Northwest Mississippi south of Tunica. Temperatures north of the front have dropped back into the 40s with 60s to lower 70s present south across portions of Northeast Mississippi. Latest 00Z HRRR and NAM indicate showers should stay mostly north of the I-40 corridor overnight. Potential for low ceilings, patchy fog and perhaps some drizzle is anticipated for the remainder of the night north of the front. Will make some adjustments to the forecast given current trends. Updated forecast will be available shortly. CJC && .PREV DISCUSSION... /issued 611 PM CDT Sun Apr 1 2018/ UPDATE... Updated to include the 00z aviation discussion. PREV DISCUSSION... /issued 232 PM CDT Sun Apr 1 2018/ DISCUSSION... Currently...a wide range of temperatures across the Midsouth with 40s in the far northwest and near 80F in the southeast...the result of a nearly stalled out cold front near I-40. A few light showers were tracking east over the area...with elevated thunderstorms just upstream along the Arkansas and Missouri border. Winds north of the front were breezy from the northeast providing for wind chills down near freezing...while south of the front winds were generally from the southeast. For tonight through tomorrow. Aforementioned front will get another push to the south tonight as a shortwave swings through the Midwest and Ohio valley. With that showers and a few elevated cracks of thunder will be possible tonight...along with some patchy drizzle and fog closer to the boundary. Temperatures will fall into upper 30s north to mid 50s south. By midday tomorrow the front will start to lift north as the surface flow turns towards a developing lee-side Low in Colorado. This should in turn diminish rain chances in the area as well...drying out the I-40 corridor and points south for the evening and overnight hours. Temperatures will warm back into the 60s and 70s south of the front...but cooler 50s will hang on across the far north. Tuesday...models are in good agreement that the surface wave in Colorado will deepen as it first tracks east across Kansas and then northeast to the southern Great Lakes. Arriving in the Chicagoland area with a 991mb central pressure by evening. Strong south to southwest winds out ahead of the low will likely prompt the issuance of a wind advisory across a large portion if not all of the area during the day. Most of the morning appears dry but by afternoon 850mb winds in the 45-60kt range will aid in the production of storms along an approaching cold front. Breaks of sunshine will allow CAPE values to potentially reach 1000-1500 j/kg...while midlevel lapse rates of near 8C stream in from the west. A few supercells along the line will be capable of damaging winds...hail of golf ball or larger size...and an isolated tornado...especially points along and west of the Mississippi River. Convection will slowly wane in intensity during the evening hours with the both the loss of instability and better dynamics shifting into the mid/Upper Ohio Valley. Highs will generally be in the 70s to near 80F...with lows Tuesday night in the 40s. Wednesday through Sunday...cooler temperatures this period...with the coldest of days being Wednesday. Clouds will start off the day...with clearing expected in the afternoon as high pressure builds in from the Lower Missouri Valley. This should set the stage for some freezing overnight lows and areas of frost for Thursday morning. Highs will climb into the 50s and 60s for Thursday and Friday. Rain chances will ramp back up late Friday as well and continue into Saturday. A few elevated storms will be embedded in the precipitation shield...but unlike Tuesday`s system the instability axis is progged to slide along the I-20 corridor. JAB && .AVIATION... /00z TAFs/ The stalled front has begun moving back to the south again and will continue through the remainder of the Mid-South through 06z. Winds will shift from the north in the wake of this front and flight conditions will deteriorate as ceilings drop to IFR (or even LIFR in some areas). Patchy drizzle and rain showers are expected to develop overnight and will reduce visibility at times. An elevated thunderstorm cannot be ruled out late tonight and early Monday, but probabilities are low at this time. The surface boundary will lift back north as a warm front on Monday, shifting winds back from the south, primarily after 18z. This will result in improving ceilings and visibility and will reduce rain chances as well. Johnson && .MEG WATCHES/WARNINGS/ADVISORIES... AR...None. MO...None. MS...None. TN...None. && $$
Area Forecast Discussion
National Weather Service New York NY
1013 PM EDT Sun Apr 1 2018 .SYNOPSIS... A quick moving low pressure system will pass to the south and east of Long Island late tonight into Monday. Another frontal system will impact the area Tuesday into Wednesday, followed by high pressure passing to the south Thursday and Thursday night. A cold front will then pass through the area on Friday and stall over the Mid Atlantic states. Low pressure forming along the front may impact the area over the weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Mdt to loc hvy snow has been reported across portions on IN tngt. The fcst is on track. NW winds this evening will usher in a colder, drier air mass that will help set the table for the snow event expected to begin late tonight. Precip could briefly mix with rain right at the onset especially in NYC metro, and could begin as early as 2-3 AM. Likely-cat PoP looks to hold off until the very end of the forecast period, and at the start of the AM commute. Given NYS Mesonet ground temps in the upper 40s and lower 50s, much of the snow at the onset likely to melt on roads, and accumulate only on grassy/elevated surface, with close to an inch possible by daybreak. Temps by daybreak should be 30-35, warmest in urban NYC metro. && .SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/... Still some questions as to exactly where bands of highest QPF will set up on Monday as fast-moving low pressure passes to the south. GFS/RAP, which were performing well with the position of banding in the Plains states this afternoon, show this axis passing just S of NYC/Long Island, while the latest extrapolated HRRR aims for Long Island, and the NAM/SREF set up more squarely over the entire area. Taking a blend of these and accounting for usual southerly model bias with frontogenetically force banding suggests this axis will skirt NYC and Long Island, running roughly from RDG-JFK-MTP. NAM 2m boundary layer temps may be a touch cold and tempered them with slightly warmer MOS, but the end result per resulting wet bulb temps still yields a precip type of snow, but with perhaps slightly lower SLR in urban NYC metro and NE NJ. Meanwhile, fcst soundings indicate a quick-hitting 3-4 hour period of moderate to even locally heavy snow possible, with snowfall rates of as much as 1-2 inches per hour as lift is maximized in the dendritic snow growth region, while lapse rates will be neutrally stable, approaching moist adiabatic. Those snowfall rates should overwhelm the warmer ground temps and allow snow to accumulate on roads mainly during and just after the AM commute. When all is said/done, expect 2-4 inch accumulation along the northernmost portion of the CWA, and 3-5 inches for NYC metro, Long Island, and coastal CT. There is potential for total accumulation of 6 inches in the higher elevations of NE NJ west of the Garden State Parkway, perhaps extending up along the Rockland/Orange border. Total accumulation on roads likely to be less than the storm total snow, so previously issued advisories for late tonight into early Mon afternoon remain in effect. Snow may briefly mix with rain before ending west to east during the mid morning to around midday, with plenty of melting Monday afternoon as temps rise into the 40s. Lows Mon night will drop into the 30s, and there is a chance for some light snow NW of NYC and a rain/snow mix in NE NJ late as the next frontal system approaches. && .LONG TERM /TUESDAY THROUGH SUNDAY/... The greatest forecast uncertainty comes next weekend with the amplification of the upper flow, with global models pointing at an amplifying trough over the eastern third of the country. There is though still much uncertainty with the details and whether there is phasing of the two streams. Before then though, an amplifying southern stream shortwave trough moves across the mid Mississippi Valley, lifting across the Great Lakes and into eastern Canada Tuesday through Thursday. This system will send a deepening surface low across the same area, sending a warm front across area the Tuesday night, followed by a strong cold frontal passage Wednesday afternoon. Overrunning rain will spread across the area during the day Tuesday with a possible dry slot Tuesday night as the area enters into the warm sector. A brief period of wintry precipitation is also possible across the interior Tuesday morning. On Wednesday, deep-layered shear coupled with marginal instability and strong frontal forcing will produce a band of moderate to heavy rain showers right along the cold front. There is even the possibility of an isolated thunderstorm. Rainfall totals for the event look to be between one-half to one inch, barring any strong convection. Strong gusty winds will likely precede and follow the cold frontal passage Wednesday with the potential for gusts up to 30 mph. Post-frontal winds could even be stronger should deeper mixing be realized behind the cold front. High pressure follows before another frontal system impacts the area Friday into Saturday. There are differences with the progression of this front through the area on Friday, with the GFS the more progressive of the operational solutions. The GGEM and ECMWF are slower and stall the front farther north across the Mid Atlantic states on Saturday with frontal wave development over the Tennessee Valley. The GFS is slower and farther north with the low track. Once again, its way to early to be specific with the details, but an inclement weekend is possible. As for temperature, it will be a roller coaster ride as a series of frontal systems impact the area. && .AVIATION /03Z MONDAY THROUGH FRIDAY/... Weak high pressure then builds to the north through as low pressure moves to the Mid-Atlantic coast by Monday morning. This low then tracks well south of Long Island into early Monday afternoon. VFR through 06z. Conditions should lower to MVFR through LIFR in snow from 7-13Z from W to east (first to MVFR KSWF last to LIFR KGON), then improve to VFR by around midday (early afternoon eastern terminals) as the snow comes to an end. The snow may briefly mix with rain at the onset/offset. Projected Snowfall Accumulations: KJFK/KLGA/KEWR/KTEB/KISP/KHPN/KBDR: 3-5" on grassy surfaces, up to 1 to locally 2 inches on runways. KSWF/KGON: 2-4", up to 2 inches on the runway at KSWF and up to 1" on the runway at KGON. N winds veer to the NE this evening at speeds around 10 kt or less. Winds should back to the NNE early Monday afternoon. .OUTLOOK FOR 00Z TUESDAY THROUGH FRIDAY... .Monday night...VFR. .Tuesday-Wednesday...IFR or lower possible, mainly in rain or rain showers. LLWS possible Tuesday afternoon-Wednesday morning. NW winds G15-25+KT possible Wednesday afternoon. .Wednesday night-Thursday...VFR. NW-W winds G20-30kt possible. .Thursday night...VFR in the evening then a low chance of MVFR late. SW-W winds G20-30+KT possible. .Friday...MVFR or lower possible in any showers. W winds G20-30KT possible. && .MARINE... Have pushed back the starting time on the SCA for the ocean waters. Winds and seas are below criteria at this time and will likely not come up until Monday morning with a strengthening northerly flow ahead of low pressure moving off the Mid Atlantic coast. For Monday, NE-N winds on the ocean will gust up to 25 kt and seas on the outer waters will build to 5-6 ft. Winds and seas again increase to SCA levels Tuesday night and Wednesday as a frontal system moves through the waters. Gales are possible Wednesday afternoon and night. Winds and seas will be gradually subside on Thursday. Another frontal system will impact the waters on Friday preceded by a strong SW flow && .HYDROLOGY... QPF around 1/2 inch (give or take 1/10 of an inch) expected on Mon, primarily as snow. Snow melt should be fairly rapid, and then followed by a potential 1/2 to 1 inch of rain with a frontal system mid week. && .EQUIPMENT... NYC NOAA Weather Radio Station KWO-35 (162.55 MHz) remains off the air. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...Winter Weather Advisory from 2 AM to 2 PM EDT Monday for CTZ005>012. NY...Winter Weather Advisory from 2 AM to 2 PM EDT Monday for NYZ067>075-078>081-176>179. NJ...Winter Weather Advisory from 2 AM to 2 PM EDT Monday for NJZ002-004-006-103>108. MARINE...Small Craft Advisory from 2 AM to 2 PM EDT Monday for ANZ350- 353-355. && $$ SYNOPSIS...Goodman/DW NEAR TERM...12/Goodman/DW SHORT TERM...Goodman LONG TERM...DW AVIATION...12 MARINE...Goodman/DW HYDROLOGY...Goodman/DW EQUIPMENT...
...Update to aviation forecast discussion...

.SHORT TERM...(This evening through Monday) Issued at 250 PM CDT Sun Apr 1 2018 20Z water vapor imagery showed broad cyclonic flow across the eastern two thirds of the country. A subtle low amplitude shortwave was noted within the flow moving along the KS/NEB state line. Further west, a closed low was propagating southeast along the British Columbian coast while another area of low pressure aloft remained nearly stationary off the southern CA coast. At the surface, high pressure was centered over the mid MO river valley with the associated cold front across northern AR and into west TX. For the late afternoon and tonight, models are in agreement that the forcing for precip will continue to diminish as the shortwave passes east of the forecast area. Radar trends already show the back edge of precip entering northeast KS. The HRRR has been reasonable with the timing of the precip so think much of the activity will exit to the east by 6 PM. Will likely be able to cancel some of the advisory early. The bigger question mark may be with the cloud cover. The RAP an to some extent the NAM keep low clouds across much of the forecast area. Because of this have kept overnight lows in the lower and middle 20s. But if clouds can clear out, lows could end up being a little cooler. For Monday the models develop a low level warm air advection pattern with moisture moving north keeping the low clouds in place across eastern KS. Additionally some decent isentropic upglide looks supportive for a chance of drizzle by mid morning and through the day. Of course with temps below freezing, there could be some light freezing drizzle during the mid to late morning. At this point, the saturation and lift look to hold off until just after the morning rush hour. With surface temps still in the upper 30s and lower 40s, the main impact from any freezing drizzle would be more likely on bridges and overpasses. Have lowered highs for Monday anticipating mostly cloudy to overcast skies over eastern KS. Here forecast soundings only mix the boundary layer to 900MB. So have highs in the middle 40s. There looks to be some clearing across north central KS which should help highs reach the lower 50s. If the clouds mix out sooner, temps over north central KS could be warmer with 925MB temps progged to warm to around +10C. .LONG TERM...(Monday night through Sunday) Issued at 250 PM CDT Sun Apr 1 2018 While models generally agree in moving a shortwave impulse and associated surface low over the area in the overnight hours Monday evening into early Tuesday morning, they continue to vary in the amount of moisture and available instability that make it into the forecast area before the low passes. NAM remains strongly capped and takes most instability to the east, while GFS and EC are similar with the cap but enough uncertainty to keep some potential for a storm to get going along then north of the warm front. Not high confidence in this but if so, hail would be the hazard and mainly between midnight and 7am. Overnight lows hold in the upper 30s to lower 40s. Rain showers end west to east through Tuesday morning as the next cold front sweeps across the area and leaves highs from around 40 north to lower 50s southeast. Wednesday and Thursday bring us back into the 50s then 60s for a short reprieve as warmer southerly flow returns to the area before the next front comes through later Thursday into Thursday night. With this will come colder temperatures once again and more chances for rain or snow, with another wave skimming over the front and keeping it cool and cloudy with a chance for precipitation into Saturday. Another break between systems could bring some recovery in temperatures on Sunday, but overall still a cool pattern for early April. && .AVIATION...(For the 00Z TAFS through 00Z Monday evening) Issued at 639 PM CDT Sun Apr 1 2018 MVFR cigs are expected to continue through 08Z with a transition to LIFR cigs as most model guidance suggests. Some mvfr vsbys are also possible with mist. Conditions are forecast to improve to IFR for TOP and FOE by 17Z, with MHK improving to MVFR, then to VFR after 21Z. Winds light to calm will increase to around 10 kts from the southeast and south after 10Z. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...Wolters LONG TERM...67 AVIATION...53