Forecast Discussions mentioning any of "HRRR" "RAP" "RUC13" "RUC" "RR" received at GSD on 06/01/18

Area Forecast Discussion
National Weather Service State College PA
952 PM EDT Thu May 31 2018 .SYNOPSIS... A deep, southerly flow of very moist, tropical air will combine with a slow moving frontal system to bring several rounds of showers and thunderstorms right into Saturday. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... It`s been a lesson in mesoscale meteorology today with convection that fired in the column of unstable air over western PA falling apart at the hands of a wedge of cool/stable air over central and eastern PA. As of 7PM, more showers and storms are moving and dying through the NW Mountains, and from portions of Bedford county east into the lower Susq Valley. Meso analysis shows the stable airmass stubbornly hanging in over about the NERN half of my forecast area so the much anticipated tropical downpours have not happened except for a few localized areas of Cambria and Clearfield counties. The HRRR does drag scattered showers eastward, but weakens them steadily as they invade the cold air damming wedge. While the tropical downpours don`t seem likely, a few showers cannot be ruled out as remnant convection moves through the region. Much of the night, the radar could be covered only sparsely with light showers, if any at all. Overnight mins will hang in the 60s again, but a little cooler than Thurs AM. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... Friday should feature a repeat of the convection with the potential for numerous, slowly progressive gully-washers as we will still be in the soupy airmass with PWATS close to 2 inches. A significant upper trough will slide in from the west. The severe threat is lower with less deep-layer shear. Drier air will attempt to push into the state behind a cold front associated with the trough. Therefore, it should dry out Fri evening over the NW, but showers will likely linger into the night in the south and east prior to the weakening front arriving there. Refer to hydro section for flooding thoughts. Max temps should be 5-8F higher than today (reaching the upper 70s to mid 80s) as a result of some decent breaks forming in the cloud cover, that should once again be quite expansive with low ceilings through the mid morning hours. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... Model and ensemble guidance offer a reasonably similar large scale pattern evolution over the Mid Atlantic region this period, trending toward more amplitude/longevity with a developing upper level low/trough. The initial upper trough should migrate across the Appalachians Friday night before closing off near the Delmarva Saturday night. The 500mb pattern takes on a mini Rex Block configuration before another upstream trough rotates southeast from the Great Lakes into the Northeast through early next week. Smaller scale perturbations embedded with the mean flow begin to complicate the upper pattern by increasing model spread and forecast uncertainty later next week. That being said, confidence is better than average in weather conditions staying "unsettled" with repeated/daily rain chances. It looks difficult to string together a few dry days. Temperatures will trending relatively cooler with the upper level trough influence holding readings near to below average for early June. The latest blends favor max rain potential over south-central and southeastern parts of central PA this weekend. Some moderate to locally heavy amounts are possible. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... 01Z RADAR still has scattered showers through the Southeast along with a line of showers approaching DUJ from the west. Restrictions from SHRA will be mainly MVFR with TSRA not expected. The latest HRRR has the convection dissipating as it continues to move eastward. This convection should diminish in both intensity and areal coverage by 04Z. Light wind, partial clearing and wet ground will then likely lead to patchy fog tonight into Friday morning. With light upslope flow in the east IFR to LIFR is possible at LNS and maybe MDT considering the light flow and low level moisture. Conditions will improve 13Z to 15Z with another round of showers and thunderstorms possible Friday after 19Z. .Outlook... Fri...AM fog possible. Scattered PM tsra impacts possible. Sat...AM low cigs possible Laurel Highlands and N Mtns. Sun...AM low cigs possible, mainly KJST/KAOO. Mon...Patchy AM fog possible. && .HYDROLOGY... Precipitable Water values in the 1.5-2.1" range today will dip slightly tonight, then climb again to nearly 2 inches for Friday. The anomalous moisture and short MBE vectors could put the region as risk for flash flooding, esp in the S and W this aftn/eve and the SW Fri. WPC excessive rain outlooks place the SLGT risk over the SW today and again Friday. The drawback to the flash flood threat will be that the HREF members all point to storms which should be moving along steadily, not training. Torrential rain for a brief time, or repeated heavy rain may lead to local problems. It could be that the rain today may not much of an impact but additional rain Fri could cause problems as the ground will soak up less rain. But, the flash flooding threat looks, for the time being, to be a little less dire than it looked yesterday. Holding with mentions of +RA and poss localized flooding in the HWO. && .CTP WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...La Corte/Lambert NEAR TERM...La Corte/Lambert SHORT TERM...Dangelo/Lambert LONG TERM...Steinbugl AVIATION...Lambert/Ceru HYDROLOGY...
Area Forecast Discussion
National Weather Service Grand Forks ND
1001 PM CDT Thu May 31 2018 .UPDATE... Issued at 959 PM CDT Thu May 31 2018 Lowered tonight low a bit...mainly in the east. Scattered storm continues in the northwest zones this evening. No other changes at this update. UPDATE Issued at 659 PM CDT Thu May 31 2018 Tweaked pops for tonight with storms already developing/moving into Towner county. Also tweaked temps and dewpoints. No other changes at this update. && .SHORT TERM...(This afternoon through Friday afternoon) Issued at 312 PM CDT Thu May 31 2018 H5 ridge axis is centrally roughly over our CWA, with southwest flow over the northern Rockies and western ND. A stalled frontal zone is in place near the International Border, with surface high pressure along the Red River Valley. Td have lingering in the upper 50s and lower 60s and with temperatures warming to the 80F range ML CAPE has increased to around 1500 J/KG according to RAP Mesoanalysis. Subsidence has helped inhibit precip potential through the afternoon period. This evening-Friday: Showers/thunderstorms developing within southwest diffluent flow over western ND/eastern Montana are shown by CAMs to transition eastward towards our CWA by late this evening through Friday morning as trough deepens and shifts eastward out of the northwest US. Instability drops off quickly ahead of this (MU CAPE below 1000 J/KG), so while shower/thunderstorm chances may increase over northeast ND severe potential is limited at least through Fri morning. LLJ develops around 15Z Friday supporting increasing winds at the surface. If this overrides lingering cold pool as WAA and instability begins to increase redevelopment may occur in our north/northwest leading to ongoing showers/thunderstorms through the day (and current CAMs are showing this). This ongoing activity could disrupt surface pattern for later Friday afternoon complicating forecast for potential severe weather later in the day and may shift better severe potential further west/southwest. Development of LLJ ahead of approaching trough should support increasing effective shear values, but instability (and whether is it primarily elevated) are much less certain through Friday afternoon. Surface obs/satellite trends will need to be monitored tomorrow for placement of favorable instability axis. In any case better severe potential is current favored by the late afternoon closer to 00Z in our west. .LONG TERM...(Friday evening through Thursday) Issued at 312 PM CDT Thu May 31 2018 The main story for this period will be the strong to severe thunderstorm potential Friday night into Saturday. A quieter period of weather Sunday through Tuesday with some chances for showers and possibly thunderstorms during the middle of next week. Temperatures cooler during this period and closer to normal than the above normal temperatures of the past few weeks of May. There are two main impacts for Friday night into Saturday: excessive rainfall and severe (mainly wind and hail). High precipitable water values are present in the models with NAEFS R-Climate percentiles above 90 percent across eastern North Dakota and parts of northwest Minnesota. In the R-Climate there are also areas at the 99.5 percentile. This combined with WPC has eastern North Dakota in a slight risk for excessive rainfall. Heavy rain could be localized due to convection in the area so rain totals could vary significantly from location to location. The areas that do get rain could have flooding concerns though, especially in locations that got heavy rain earlier this week. For the severe threat the biggest risk area will be to our west in central North Dakota but storms that fire to our west could survive into our area and cause severe concerns. This is driven by an upper level short wave that moves into the Northern Plains. The best conditions will be in southeast North Dakota where ML CAPE values near 3000 J/kg will be possible. This combined with 0 to 6 km bulk shear of 40 to 50 knots will provide an environment favorable for maintaining strong storms. In current model guidance the shear is favorable in the Red River Valley and east but the CAPE does not extend very far to the east. This is why southeast North Dakota has the best chance as it has more CAPE than areas to the north in model guidance. Current models suggest that the convective mode will become linear as it moves east into our region from central North Dakota. Confidence in convective mode will increase as we get closer to the event as the CAMs will begin to resolve more of the system. Low level shear is rather strong with values in the NAM 3km of 150 m2/s2 for 0 to 1 km SRH which means low level rotation could occur and lead to tornadoes. Friday evening and night will be the main time for potential severe weather. Saturday additional showers and thunderstorms will be present as the surface low moves through southern Manitoba but severe weather is unlikely. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 659 PM CDT Thu May 31 2018 MVFR conditions were located over north central MN roughly north of a line from Kelliher to Badger MN. Elsewhere thunderstorms over Towner county may produce MVFR-IFR conditions overnight. Precip expected to affect the northwest zones this evening and more of the western zones toward morning. Expect MVFR conditions to remain over the northeast zones overnight and Fri morning. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...None. MN...None. && $$ UPDATE...JH SHORT TERM...DJR LONG TERM...NC AVIATION...JH
Area Forecast Discussion
National Weather Service Houston/Galveston TX
951 PM CDT Thu May 31 2018 .UPDATE... Warm and winds still up at 5-10 knots with gusts at few locations. Current forecast looking close in the short term so only cosmetic changes to the skies and dewpoints. Sunday still looking interesting along the southward sagging frontal boundary. Primarily looks like a 2 pm to 10 pm window of opportunity. Model soundings certainly support strong gusty winds with abundant CAPE and minimal CIN. May be flirting with severe potential for that period. 45 && .PREV DISCUSSION... /ISSUED 704 PM CDT Thu May 31 2018/ AVIATION... VFR conditions this evening and tonight may briefly drop to MVFR as stratocumulus develop near the coast and spread inland. Have pushed up onset for TEMPO groups reflecting this based on low level condensation pressure deficits in hi-res guidance and trends in HRRR ceilings, with 04-10Z appearing to be the best window for impacts within the 00Z TAF package. Outside of intermittent ceilings, a slightly weaker surface pressure gradient tonight may also create brief windows for patchy MVFR fog development at LBX, CXO, and possibly SGR. Confidence was not high enough in development to include in the TAFs with this issuance. Expect VFR to prevail at all terminals after sunrise. Otherwise, southerly winds 10-20 knots now are expected to drop below 10 knots by mid to late evening, increasing into the 10-15 knot range by mid- morning. Huffman PREV DISCUSSION... /ISSUED 307 PM CDT Thu May 31 2018/ SHORT TERM [Tonight Through Friday Night]... Radar imagery paints a quiet picture over SE TX this afternoon, with only the occasional widely scattered shower pushing inland producing a light sprinkle or two over the coastal counties. Heights continue to rise as surface high pressure builds in from the east, also allowing the surface winds to turn out of the southeast. Aloft, the upper-level ridge is nudging northward and should eventually shift over Texas as we move into the weekend. Northwesterly flow around this upper level region of high pressure is helping to provide a strong cap or pocket of dry air in the mid to upper layers of the atmosphere. This strong cap will also act to hinder further development of any light showers that develop this afternoon, as well as on Friday. A similar set up is in store for tomorrow, with high temperatures a touch warmer by a degree or two tomorrow into the mid 90s due to the stronger influence of this upper level ridge. Hathaway LONG TERM [Saturday Through Thursday]... As a surface low tracks eastward across north Texas Saturday, surface winds will turn more southwesterly sandwiched between this region of low pressure and the surface high located just east the region. This wind shift could help to lower dewpoints a touch Saturday, advecting in slightly drier air. Forecast soundings show slightly lower precipitable water values (PWs) Saturday ranging between 1.2-1.4 inches. The boundary located over northeast Texas Saturday night slowly transitions southeastward Sunday, increasing our PoPs to a slight chance for showers and thunderstorms mainly north of I-10 Sunday afternoon. In the most recent runs of both the GFS and ECMWF, this boundary looks to have slowed, stalling along the coast by Monday morning. There will not be much of a change in the overall airmass behind this feature, besides potentially a small dip in dewpoints bringing in slightly drier air for a short period of time Monday. This lingering boundary Monday, could also help to provide a slight chance for showers for showers and thunderstorms through the afternoon hours. Temperatures will remain above normal through next week. High temperatures Monday through Thursday are expected to rise into the mid to upper 90s, with low temperatures falling into the mid 70s to low 80s. Hathaway MARINE... Will raise the caution flags again tonight for the offshore waters as winds speeds slightly increase into the 15-20kt range. They should taper off before sunrise. Otherwise, expect light to moderate onshore winds to continue. Winds will become more southwesterly this weekend as surface high pressure over the east central Gulf expands further westward. 47 && .PRELIMINARY POINT TEMPS/POPS... College Station (CLL) 75 97 75 97 75 / 0 0 0 10 10 Houston (IAH) 77 95 76 96 76 / 0 0 0 10 0 Galveston (GLS) 82 88 82 89 81 / 10 10 0 10 0 && .HGX WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...SMALL CRAFT SHOULD EXERCISE CAUTION until 4 AM CDT Friday for the following zones: Waters from Freeport to Matagorda Ship Channel TX from 20 to 60 NM...Waters from High Island to Freeport TX from 20 to 60 NM. && $$ Discussion...45
Area Forecast Discussion
National Weather Service Huntsville AL
1047 PM CDT Thu May 31 2018 .NEAR TERM...(Rest of tonight) Issued at 1047 PM CDT Thu May 31 2018 A few thunderstorms popped up in Southern Middle TN this evening from an outflow boundary that came from convection NW of the area. Despite loosing some daytime heating, there was enough instability in place that these storms quickly became severe. Dime to quarter sized hail was reported in Franklin Co TN, while small hail and a downed tree was reported down in Moore Co. These storms have since weakened and moved out of the forecast area. However, there will be another round of showers and storms moving in after midnight. The convective activity currently in the Mid MS Valley will develop into a line as it sinks SE overnight as a shortwave trough swings into the region. Models are in a disagreement on the arrival time for this next round with the HRRR having a faster solution of 09Z and the NAM on the slower side of early tomorrow afternoon. Regardless, the line will be moving into warm, moist and unstable air. Tonight`s temps will be mild in the lower 70s which could flirt with record high mins: MSL 75 (1899), HSV 73 (2013). .SHORT TERM...(Friday through Saturday) Issued at 250 PM CDT Thu May 31 2018 Models move this upper level trough axis into northern Alabama Friday morning. This boundary continues to say south during the day. There might be a brief window of just a bit of sunshine near/south of the Tennessee river just after daybreak, but this will quickly go aways as an area of showers and thunderstorms push south into the area. A little bit of shear could help this activity be a bit more organized than typical pulse summertime activity. With dry air aloft and deeper moist conditions in the lower levels, damaging winds look possible in strongest thunderstorms. Thus, strong to marginally severe storms look like a good possibility on Friday into Friday evening, before becoming scattered in nature. Some drier air should push in behind this trough axis on Saturday, making it a bit more comfortable. However, it will be warmer with highs west of I-65 climbing to around 93 or 94 degrees. Heat index values around 100 degrees look possible in northwestern Alabama as a result. Guidance continues to moves a strong shortwave pushes southeast into the area via northwesterly flow Saturday night. Thunderstorm activity could be strong to marginally severe, with good shear and decent instability ahead of this system. .LONG TERM...(Saturday night through Wednesday) Issued at 250 PM CDT Thu May 31 2018 Sunday will begin as a cloudy and humid day, with some lingering showers and storms behind the initial MCS complex progged to move across the region late Saturday. This activity should begin to wane by late morning into the early afternoon as it dissipates and shifts off to the south and east. A dry forecast is expected for the remainder of the day, with highs reaching the mid to upper 80s. With dewpoints dropping into the middle 60s, it will also feel more pleasant outdoors -- a good way to cap off the weekend. A surface high will move into the region late Sunday into Monday as temperatures will remain at or just below normal for early June. The Tennessee Valley will be caught in between two pressure systems through at least the middle part of next week: A strong area of high pressure over the Southern Plains of TX/OK and fairly notable closed upper-low over the Northeast/Mid-Atlantic. These features will enhance a more northerly flow aloft and generally promote dry and cooler conditions, with high temperatures in the low to mid 80s on Monday, Tuesday, and Wednesday of the upcoming work week. In fact, there may be a reinforcing shot of "cooler" air (from a weak shortwave) on Tuesday/Wednesday which may maintain these conditions through the first full week of June. With drier air at the surface and stronger capping in place, the possibility of pulse, diurnal convection should be quite low and have kept PoPs below mentionable levels. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) Issued at 644 PM CDT Thu May 31 2018 VFR conditions will prevail through the TAF period. Winds will diminish with sunset, along with the chance for showers this evening. However showers and thunderstorms will move into the area early Friday morning. Kept with VCTS throughout the day due to low confidence in timing. && .HUN WATCHES/WARNINGS/ADVISORIES... AL...NONE. TN...NONE. && $$ NEAR TERM...JMS SHORT TERM...KTW LONG TERM...AMP.24 AVIATION...JMS For more information please visit our website at
Area Forecast Discussion
National Weather Service Wilmington NC
938 PM EDT Thu May 31 2018 .SYNOPSIS... The heat will build into the weekend. Scattered showers and thunderstorms this evening will be much fewer late tonight and through Saturday. Showers and thunderstorms may be on the increase Sunday along and ahead of a cold front. High pressure building south should bring much drier air and lower humidity levels mid and late next week. && .NEAR TERM /THROUGH FRIDAY/... As of 930 PM Thursday...Inherited forecast remains on track. Mid-level impulse is pulling off to the NE, with winds expected to slowly shift around to the W through the overnight. Western portions of the CWA which experienced more sunshine and hence more instability this aftn continue to have scattered showers and tstms, but a weakening trend is noted. SPC Mesoanalysis shows parcels capped to the surface now, and although MUCape remains, it is becoming weak, especially as convective elements head east into the more stable airmass. Best chance for any stronger storms will be Florence, Williamsburg, and Georgetown counties the next few hours which are still most unstable. Even these stronger storms are unlikely to feature any significant hazards outside of lightning though. While storm motion is generally increasing due to cold pool interaction and strengthening low-level winds behind the departing mid-level circulation, DCape is lowering and momentum transfer to the surface is becoming more difficult as surface stability increases. Even the heavy rain threat is reduced now thanks to this faster storm motion. Eastern portions of the CWA may catch the tail end of these weakening storms, but will mostly experience isolated showers thanks to forcing from the mid-levels and instability within the residual layer. High-res guidance is in good agreement that most of this will wane after midnight and expect primarily a dry overnight period. Previous discussion below: As of 645 PM Thursday...Satellite imagery reveals a well-defined mid-level circulation is moving across the area now, but with a relative void of shower and thunderstorm activity near the center of circulation. This is likely due to earlier clouds and showers that created a more stable airmass across much of the area between I-95 and the coast. Where better instability exists west of I-95 there has been a resurgence of thunderstorms across Darlington and Marlboro counties, and this activity may survive for another couple hours as it moves eastward toward Florence and Dillon. Locally heavy rainfall is expected due to slow movement and high precipitable water values. A squall line dropping through the foothills of the Carolinas is shown by the majority of models to dissipate before making it this far east. However the HRRR shows some showers getting into the Pee Dee region a little before midnight, so I`ll maintain a small PoP here through early Friday morning. Otherwise, the airmass should generally dry out overnight as the steering flow turns more westerly behind the departing mid- level swirl. Precipitable water values currently around 2.1 inches should fall to 1.7 inches overnight, mainly due to a loss of moisture in the 850-500 mb layer. Forecast lows range from 70-74 degrees, still on the high end of guidance due to recent model performance, but not as exceptionally warm as we`ve seen recently as the airmass begins to dry. && .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...Despite a continuation of very high precipitable water in place Friday night will not offer significant rainfall chances. Some weak upper level impulses will be moving overhead but guidance is fairly insistent that other than perhaps a few sprinkles the mid level dry air will not support measurable precipitation. And given the oft moist bias of models (especially when PW values are at 90% for the date) I`m not inclined to disagree. Mid levels remain just enough into Saturday while steep surface-based lapse rates really dry out the low levels on Saturday, which is shaping up to be a partly sunny and warm afternoon with highs into the low 90s. Instability should be sufficient for isolated thunderstorms mainly along the sea breeze, who`s inland progress will be minimal due to low level offshore flow. Ascent along the seabreeze should be bolstered by a mid level impulse traversing the area in the NW flow. A weak boundary may drop into the area Saturday night though some guidance such as the WRF is backing away from this idea and keeping it well to the north. Expect a warm and muggy night with generally rain-free conditions. && .LONG TERM /SUNDAY THROUGH THURSDAY/... As of 300 PM Thursday...A pronounced ridge in the western CONUS will persist during this portion of the forecast. A series of upper lows diving out of southeast Canada will help to maintain a trough across the East Coast of the U.S. One upper low across the northern Mid-Atlantic Sun morning will be absorbed by a larger and stronger system. This second upper low diving SE across the Great Lakes region will reach the Mid-Atlantic area Mon night and Tue and then E of New England Tue night. Another upper low dropping out of southeast Canada will then merge with this system across the Canadian Maritimes Wed night and Thu. The brunt of shortwave energy rotating around these upper lows will skirt by to our N. However, we will be on the southern periphery of one shortwave late Sun and Sun eve and then another late Mon into Tue. At the surface, a cold front should be moving through the area during Sun and the column does begin to noticeably dry out thereafter and especially in the mid levels. This front should sag all the way to the Gulf Coast and well offshore through Thu as Canadian high pressure builds down the East Coast. If this scenario holds, then lower POPs are warranted as we move through the forecast period and will actually keep POPs below threshold Thu with increasing sunshine, especially by Wed and Thu. Much lower dewpoints are expected to work their way into the forecast area mid and late week. Dewpoints in the summery low and mid 70s Sun will drop into the 60s Mon and Tue and perhaps as low as around 60 Wed and Thu. High temps will be warmest Sun, around 90. For the remainder of the period, highs will be in the 80s. Lows will be as cool as the lower 60s Wed night and Thu night. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... As of 23Z...Moisture profiles in the lowest few thousand of the atmosphere are marginally conducive for stratus formation late tonight, but W-WSW wind flow in the boundary layer may prevent large-areas or widespread IFR/MVFR ceilings, but SCT010 looks like a good bet at a few terminals. In the very near term, KLBT and KFLO, VCTS through 02z based on radar trends and a diurnal expectation of a diminishing trend into late evening. Friday mid-levels appear dry, and am not forecasting SHRA/TSTMS for Friday, but do count on moderate cumulus about the region through the afternoon. VFR will be the rule for Friday, with manageable south low-level wind flow. Extended Outlook...Primarily VFR. Tempo MVFR/IFR in early morning fog/stratus 09z-13z, or briefly in isolated showers and TSTMS. && .MARINE... NEAR TERM /THROUGH FRIDAY/... As of 645 PM Thursday...Southerly winds 10-15 kt are gusting to 17-18 kt on recent buoy and pier reports, mainly due to this afternoon`s seabreeze circulation. As the seabreeze dies away, the overall synoptic wind should increase as a moderate low- level jet develops just off the surface. This should push sustained winds up to around 15 kt with gusts near 20 kt. Seas currently reported at only 2-3 feet at area buoys should build by around a foot overnight, with 4-foot seas becoming quite widespread after midnight. The potential of 5+ foot seas may not be quite as significant across the coastal waters as earlier thought, so the `exercise caution` headline has been dropped from the forecast. SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/... As of 300 PM Thursday...Southwesterly flow and predominantly wind waves will be in place through the period; as longer period swell energy largely gets channeled east of the forecast zones. Still looking for a general 10-15kt of wind but with afternoons growing so warm a few afternoon/evening gusts to 20kt appear possible. Seas will continue to average 2-3 and occasionally 4 ft. LONG TERM /SUNDAY THROUGH TUESDAY/... As of 300 PM Thursday...SW winds will hold into Sun, but are expected to shift to NW Sun night in the wake of a cold front. Northerly to northeasterly winds will dominate Mon and Mon night. The wind direction should briefly become southwesterly late Tue/Tue night ahead of a trough. Wind speeds will be 10 kt or less, except up to near 15 kt later Sun and Sun eve. Seas will be 2 to 3 ft, except up to 3 to 4 ft Sun night. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...None. NC...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM...TRA/JDW SHORT TERM...MBB LONG TERM...RJD AVIATION...MJC MARINE...
Area Forecast Discussion
National Weather Service Wilmington OH
1005 PM EDT Thu May 31 2018 .SYNOPSIS... A series of upper level disturbances will move through the Ohio Valley through Friday, resulting in a continued chance of thunderstorms. Weak high pressure will provide for dry conditions on Saturday before another disturbance brings more storms on Sunday and Monday. High pressure will then build in for the remainder of next week. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... Next round of thunderstorms are moving through Indiana and Kentucky towards the region. Latest runs of the HRRR and RAP seem to have a good handle on the situation. They weaken the convection in nrn IN/nw OH as it comes east this evening. Meanwhile the convection in far sw Indiana, is forecast to lift ne towards the Cinci tri-state, arriving between 06Z-09Z. This area works east along the Ohio River for the rest of the night. Upped PoPs to likely with the srn convection, but this might need to be increased if it holds together better. Cant rule out spotty cells elsewhere in the fa, so went chance PoPs elsewhere. Kept lows in the upper 60s for tonight. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/... While there will be numerous upper level vorticity maxima over the region, the axis of the trough will nose into western CWA by daybreak Friday, be along the I-71 corridor by 18Z, then be east and out of the area by evening. Surface front will lag behind this and a few lingering showers or thunderstorms may persist over the CWA Friday evening and show a decrease in coverage and intensity overnight, exiting to the southeast by daybreak. Surface front will be over the Ohio River towards midnight with rapidly improving conditions overnight. Tonight`s low temperatures will drop to 67-69 degrees across the board, and tomorrow`s highs will be muted to be within a few degrees of 80. Cooler air will result behind the surface frontal passage by Saturday morning, ranging from the upper 50s to around 60 in the I-70 corridor, to the middle 60s over Kentucky and immediate Ohio River Valley. && .LONG TERM /SATURDAY THROUGH THURSDAY/... High pressure at the surface and aloft will move into the region on Saturday. Some models try to develop a few instability showers near our eastern border, but have decided to keep a dry forecast for now. Highs will range from the upper 70s to the lower 80s. It now appears that s/wv energy will dig southeast in the northwest flow aloft, and affect the region late Saturday night into Sunday. This will be associated with a cold front, which will bring a chance of showers and thunderstorms. After lows in the upper 50s to the mid 60s, highs again will generally be in the upper 70s to the lower 80s. The GFS is more of an outlier as we head into the first part of next week, digging an upper level low faster and farther south into the Great Lakes and Ohio Valley. Have leaned more toward the ECMWF/CMC which keep the low farther north and a little slower in its digging. In any case, a weak front should drop south through the region on Tuesday, with a low chance of showers and thunderstorms. High temperatures will cool some into the 75 to 80 degree range Monday into Tuesday. For the remainder of the extended, Wednesday and Thursday, under a northwest flow aloft and generalized surface high pressure, dry weather is expected. Highs 75 to 80 on Wednesday will warm slightly by Thursday into the lower 80s. && .AVIATION /02Z FRIDAY THROUGH TUESDAY/... Tafs are currently in a lull from the convection, as this afternoon`s round has ended. Convection over wrn Indiana is forecast by the models to reach the fa overnight. Models are showing the storms weakening as they come in, so timing them into the tafs is tricky. Waited until 09Z to add VCTS to the wrn tafs when the consensus has convection associated with a h5 s/w move in. May have to update timing if the storms hold together. Time sections are suggesting the possibility of MVFR stratus forming towards sunrise. The chance of MVFR cigs last until about 14Z. Scattered convection will continue during the day Friday, as H5 s/w swings through. Went with VCTS to cover the threat through the end of the tafs. OUTLOOK...Thunderstorms are possible Sunday. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...None. KY...None. IN...None. && $$ SYNOPSIS...Franks/Sites NEAR TERM...Sites SHORT TERM...Franks LONG TERM...Hickman AVIATION...Sites
Area Forecast Discussion
National Weather Service Jackson MS
936 PM CDT Thu May 31 2018 .UPDATE... Updated for evening discussion. && .DISCUSSION... Currently across Mississippi it`s calm and quiet. An MCS has developed over southern Missouri in the past few hours and continues its progression towards the southeast. Rain chances, if any, from this system will be confined to our northernmost counties. The forecast was updated to include patchy fog that could develop across south central and northeastern Mississippi early tomorrow morning. Temperatures will be a bit warmer overnight tonight only dropping into the mid 70s across the state./CW/ Prior discussion below: Rest of today through tomorrow... Ridging is currently in place across northern Mexico into south Texas with a shortwave trough embedded in the westerly flow over the middle Mississippi River Valley. Numerous areas of deep convection are ongoing to our north and are expected to remain displaced from the ArkLaMiss. The only exception will be the potential for a progressive MCS to develop over northern Arkansas and move southeast towards the ArkLaMiss Delta region later tonight. 12z CAM guidance and latest HRRR runs have lacked consistency with respect to this MCS and the nocturnal timing will support a decaying trend as it approaches the area. As such, while a few decaying storms associated with any remnant MCS cannot be ruled out early tomorrow morning over the northwest Delta, overall confidence remains too low at this time to support higher rain chances or introduction of a severe threat in the HWO/graphics but the potential will have to be monitored. On Friday, the main story will be the continued heat stress with afternoon high temperatures reaching the low to mid 90s across much of the area with a humid airmass remaining in place. This will result in widespread 100-105 degree heat index values with the hottest temperatures over the Delta. Will continue to highlight this with the ongoing limited risk for heat in the HWO/graphics. A few afternoon thunderstorms will be possible mainly in northern and eastern portions of the area where any remnant outflow boundary from overnight convection could help initiate storms. However, given the aforementioned uncertainty with tonight`s MCS potential the confidence in placement of convection tomorrow is also low. /TW/ Friday night through next week... A warm, active, and fairly progressive regime will be featured in the long term portion of the forecast. On Friday night/Saturday morning, an upper level ridge will continue to build over the eastern Plains, nudging into our region and resulting in northwest flow. The current forecast mentions a slight chance of thunderstorms in the northern sections of our region during this period to account for the possibility of a decaying MCS entering the region. The ridge will continue to dampen and slide eastward through the day on Saturday as a deep upper trough begins to form over the northern Plains. The main threat to the citizens of the ArkLaMiss on Saturday will be the warm temperatures. Temps will surge into the mid to upper 90`s and combine with increasing moisture values(dew points in the low to mid 70s) to result in heat indices ranging from 100-105 throughout the region. Temperatures in this range will pose a threat to groups who will spend the day outside on Saturday without proper shade and hydration. Confidence of widespread 105+ heat indices wasn`t high enough at this point to issue a Heat Advisory for Saturday but one may be needed later if confidence grows. The aforementioned trough forming across the Plains will begin to approach the Great Lakes late on Saturday and into early Sunday, dragging a cold front that will stretch from the Canadian Border to the Lower MS River Valley. Storms ahead of and along this front will move into the northern sections of our region late Saturday into early Sunday. A few of these storms could become severe with a main threat of wind damage and hail up to the size a quarter. The front will continue to push through our area on Sunday. However, areas that are able to warm enough ahead of the frontal passage could see heat index readings in excess of 100 degrees on Sunday afternoon. This will be possible mainly in the Pinebelt. Drier, cooler air will move into the region behind the front. A building ridge over the Desert SW will result in NW flow over the region through early next week. This will keep temperatures seasonal. Long term models do hint at a possible disturbance developing in the NW flow aloft helping to push an MCS type system through the region anywhere from late Tuesday into Wednesday. && .AVIATION... 00Z TAF discussion: VFR conditions with southerly surface wind will prevail during this TAF period. The exception will be the potential for early morning MVFR category stratus development in the HBG/PIB/MEI area. There is some potential for a few storms to push south toward the GLH/GWO area late tonight, but the threat is not high enough to indicate in TAFs at this time. /EC/ && .PRELIMINARY POINT TEMPS/POPS... Jackson 73 93 74 93 / 3 6 3 22 Meridian 73 94 73 93 / 2 13 6 31 Vicksburg 74 93 74 94 / 1 3 3 10 Hattiesburg 72 93 74 94 / 1 11 5 27 Natchez 73 92 74 93 / 1 8 4 13 Greenville 76 92 75 95 / 3 10 17 22 Greenwood 76 92 74 93 / 9 14 17 22 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...None. LA...None. AR...None. && $$
National Weather Service Jackson KY
1045 PM EDT Thu May 31 2018 .UPDATE... Issued at 1046 PM EDT THU MAY 31 2018 The activity from earlier convection continues to wane this late evening hour. The trend has been evident in radar returns and IR satellite data and think based on the HIRES CAMs this seems reasonable. The CAMs seem to be initializing well and some are showing some of the upstream convection making it east later tonight. However, much of the region remains quite worked over from earlier convection and this is evident on the thermodynamic parameters in the SPC Mesoanalysis data. Therefore, it would seem the more robust upstream convection will decrease in intensity as it works east through the night. Did update POPs to reflect the latest trends and also updated grids to reflect the latest obs and trends. UPDATE Issued at 839 PM EDT THU MAY 31 2018 WSR-88D radar shows greatest concentration of stronger storms and heaviest rain remains in south central Kentucky and Cumberland Valley regions this evening. Given that much of the areas to the north and east are seeing lower rainfall rates under stratiform precipitation did drop the Flash Flood Watch for portions of Eastern Kentucky. See the Flash Flood Watch statement for more details. Also, adjusted POPs to better deal with the latest obs and trends, and the CAMs remain unclear on the evolution of convection tonight. The HRRR seems to have the better overall handle and was able to adjust from that point. All grids have been adjusted and sent. UPDATE Issued at 604 PM EDT THU MAY 31 2018 The latest scans of the WSR-88D radar continue to show the better coverage of stronger thunderstorms is now concentrated in the Lake Cumberland region. Otherwise, we will continue to monitor the flash flood threat in areas that have received larger amounts of rainfall. The good news is areas north of the stronger convection is more in the form of stratiform precipitation with much less rainfall rates. Updated the grids to better portray the current radar trends, but CAMs are not much help given the difficult time they are having dealing with the convective trends. && .SHORT TERM...(This evening through Friday night) Issued at 506 PM EDT THU MAY 31 2018 Cold pool dominated MCS has weakened considerably as it crossed the area, but has led to some training storms on the southern flank of the downdraft leading to some potential flash flooding. Another MCS is spreading into the area and will bring one last round of heavy rainfall and potentially some strong winds as it crosses the area over the next few hours. This should act to finally push out the lingering boundaries and end the heavy rain threat by later this evening. Until then, the flash flood threat will continue and possibly the need for a few warnings. Still lots of moist air feeding this activity with PW`s well above 1 inch. Some uncertainty what will happen overnight as instability will be zapped and we may see a lull late tonight into Friday morning. Another round of showers and storms will push through tomorrow with a cold front which should be our last more widespread event of the week. Localized heavy rain will again be possible, but the severe threat will be less. Some isolated showers or drizzle could hang on post frontal Saturday night, but should not be significant rainfall. .LONG TERM...(Saturday through Thursday) Issued at 241 PM EDT THU MAY 31 2018 The extended portion of the forecast begins on Saturday with an active upper level pattern in place. Expect a pattern with an increase in amplitude as the models suggest a ridge building in the western CONUS with a trough setting up over the east. Closer to the surface, on Saturday an exiting cold front will be slow to shift east with lingering high pressure to the east. This will likely keep a focus of shower and thunderstorm over far eastern Kentucky. Thus will keep pops over the east for Saturday. For Sunday, a second trough will track over the ridge in the west that has shifted east slightly in the Plains. This wave will then track southeast into the OH Valley. Model soundings suggest ample instability for this event. Thus will expect another round of showers and thunderstorms for Sunday and Sunday night. The mentioned upper level ridge will shift east as well through the period. The mid level subsidence will eventually work its way into eastern Kentucky by Monday. This will result in a dry period across the area through the rest of the extended. Given the northwest flow setting up, a shortwave could clip the northeastern portion of the CWA for Tuesday afternoon. Otherwise, will expect a dry period for much of the rest of the extended with much cooler high temperatures. In fact, these temps are more in the normal range for this time of year. && .AVIATION...(For the 00Z TAFS through 00Z Friday evening) ISSUED AT 735 PM EDT THU MAY 31 2018 The latest radar and lightning data show the greatest concentration of stronger showers and thunderstorms are in parts of the Tennessee Valley and south central Kentucky. This could cause temporary restrictions at times through the evening, but most of the TAF sites will probably escape the stronger storms seen across south central Kentucky. Otherwise, some TAF sites north and east are seeing some clearing and this could lead to lower CIGs or VIS, but it is some what unclear how this will trend overall. Given this, will lower VIS at SYM, LOZ, and SME, but the overall uncertain how other sites will trend at this time. A weakening frontal boundary will cross the region Friday and lead to the potential for more showers and thunderstorms in the afternoon. The winds will generally remain light outside of thunderstorms. && .JKL WATCHES/WARNINGS/ADVISORIES... Flash Flood Watch until 2 AM EDT Friday for KYZ068-069-079-080- 083>088-116-117. && $$ UPDATE...DJ SHORT TERM...KAS LONG TERM...SHALLENBERGER AVIATION...DJ
Area Forecast Discussion
National Weather Service Louisville KY
837 PM EDT Thu May 31 2018 .Mesoscale Update... Issued at 830 PM EDT Thu May 31 2018 Convection is diminishing over south central Kentucky, but the next round is really lighting up over extreme southern Illinois. Hi-res models have been inconsistent on how well this will hold together as it pushes east through the night, so confidence still isn`t too high beyond about 06Z east of I-65. Still think the SVR threat is low but non-zero in our area, but the bigger deal is the flooding threat, especially in the Bluegrass and along the Tennessee border. Have tweaked the Flash Flood Watch to better capture the areas that received heavy rain today. Otherwise will see a return of scattered storms later tonight. Updates on the way shortly. Issued at 552 PM EDT Thu May 31 2018 Will end Severe Thunderstorm Watch 136 for the remaining few counties, as the convection has shifted into the very southern tier of the Commonwealth. Cells continue to develop back across western Kentucky, so even as the severe threat diminishes we will have to continue to monitor the hydro threat, for possible southward expansion (or shifting) of the Flash Flood Watch. Issued at 450 PM EDT Thu May 31 2018 Squall line has pushed through the Bluegrass, allowing us to drop all but the southernmost tier of counties from Severe Thunderstorm Watch 136. Moderate stratiform rain continues across the Bluegrass region, and will slow the recovery of any flooded areas from earlier this afternoon, so flood warnings and advisories continue into early evening. Main convective focus is across south-central Kentucky, where strong surface-based CAPE is still present, as well as around 1300 J/kg of downdraft CAPE. We`ll handle that with warnings rather than a Watch extension that will end up completely beyond the original watch. Otherwise keeping an eye on the next round of convection across western Kentucky, as that will continue at least some threat of severe weather, and a bigger threat of flash flooding well into the night. && .Short Term...(This evening through Friday) Issued at 300 PM EDT Wed May 31 2018 ...Severe Weather Through This Evening Including Flash Flooding... Several clusters and lines of strong to severe thunderstorms occurring across much of southern Indiana and central Kentucky today. The storms have had a history of producing damaging winds, bringing down power lines and trees. Torrential rainfall has led to flash flooding in some areas. In the near term, the heart of the forecast concerns is over the next several hours. Environment certainly remains supportive of strong to severe storms in the next 2-3 hours as the long-lived line of storms continues east of I-65. While some areas have been convectively overturned, enough instability recover may lead to damaging wind gusts and small hail. Much more uncertainty resides in how the evening forecast will play out. The HRRR has been very consistent in showing additional convective initiation across southern IL, western KY in the 3-4 hours and then this propagate toward south-central and central Kentucky late this afternoon through the evening. This seems reasonable given that those areas have seen little thunderstorm activity and have plenty of instability to work with. Additional, shear is expected to be on the increase in the evening, so despite some waning instability, better shear will maintain the severe threat there. Flash Flooding will also be a concern across most of the area. The environment is certainly supportive of excessive rainfall given PWATs are running 1.7 to near 2.0 inches and dewpoints remain in the low 70s. The earlier storms produced flooding across the Bluegrass. Flash Flood guidance is about 2.0 inches in 1 hour, but in areas that picked up high amounts already, those values aren`t necessarily representative and are lower. Hi-res models are consistent showing a swath of 2-4 inches locally across central KY and perhaps up into southern IN. This is due to the several rounds of storms. With this in mind, went with a Flash Flood Watch through this evening. Tonight - Friday Storms will be on the decrease late tonight giving way to scattered showers and isolated storms overnight but severe storms are not expected. The current storms should push an effective boundary into Tennessee. Most of Friday is expected to be less active but another front drops through from the north in the afternoon/evening hours. It could fire up a few thunderstorms but aren`t expected to be severe. Highs will be in the 80s. .Long Term...(Friday night through Thursday) Issued at 305 PM EDT Thu May 31 2018 Drier and less humid conditions are expected on Saturday. Highs are expected to top out in the 80s. For Saturday night and into Sunday, another quick moving upper level disturbance is forecast to cross the region. This feature will bring another round of showers and thunderstorms to the area. The best chances for rainfall would be late Saturday night and through Sunday morning with a drier conditions arriving Sunday evening. Lows Saturday night look to cool into the low-mid 60s, with highs on Sunday staying in the lower 80s. Next week looks to be less active. The model consensus was used to show mostly dry conditions Monday through Friday in the northwest flow aloft and high pressure at the surface. Temperatures will gradually warm from near normal to well above normal through the week. && .Aviation...(00Z TAF Issuance) Issued at 725 PM EDT Thu May 31 2018 Low-confidence forecast as everything hinges on eventual convective development overnight. Can initialize BWG with showers and VCTS, with MVFR cig/vis staying just above fuel-alternate. SDF, LEX, and HNB all remain dry with scattered mid-level decks and cirrus ceiling. Greatest convective impact will be in BWG where showers and storms could be intermittent through the night. Have included TEMPO groups in the other terminals around or just after midnight for TSRA, with SDF going in and out of fuel-alternate between 03-07Z as a few storms ride just far enough north to brush the area. Similar theme with LEX, only later in the night. HNB will clear out just enough for some low clouds and fog around daybreak, so will carry TEMPO IFR there but others should remain no worse than high-end MVFR. Winds shift to NW on Fri afternoon, and while we can`t rule out a pop-up shower or storm, confidence is too low to mention in the TAFs. && .LMK WATCHES/WARNINGS/ADVISORIES... IN...Flash Flood Watch until 1 AM CDT Friday for INZ089. KY...Flash Flood Watch until 2 AM EDT /1 AM CDT/ Friday for KYZ023>029-034-035-038>041-045>048-053>057-061>067-071- 073>078-081-082. && $$ Mesoscale...RAS Short Term...ZT Long Term...ZT Aviation...RAS
Area Forecast Discussion
National Weather Service Nashville TN
949 PM CDT Thu May 31 2018 .UPDATE... FOR EVENING DISCUSSION. && .DISCUSSION... Earlier strong to severe thunderstorms that affected much of our eastern counties through the afternoon and evening have mostly moved into eastern Tennessee except for a few strays in Coffee and Grundy Counties. Outflow boundary from this earlier activity has pushed westward and stalled roughly along the I-24 corridor, with temperatures now well below forecast lows across eastern zones due to the rain-cooled air. Went ahead and adjusted lows downward in that area, but kept them near previous values over western zones. Looking upstream, additional strong to severe thunderstorms are ongoing across much of southeast Missouri, southern Illinois, and northern Arkansas, and this activity is expected to congeal into an MCS and push east-southeastward as a strong shortwave aloft moves across the region. Latest HRRR and HREF model runs as well as timing of current storm motions indicate these storms will reach our northwest counties around midnight or so, then continue southeast before exiting the area by 11-12Z. 00Z OHX sounding showed a very moist and unstable airmass was in place with a PWAT near 2 inches and MLCAPE around 2500 J/Kg along with steep low and mid level lapse rates around 7 degrees C/Km and deep layer shear around 30 knots, all of which is favorable for strong to severe thunderstorms overnight. However, HRRR/HREF models both suggests storms will gradually weaken overnight with the loss of daytime heating and instability, so it remains uncertain how strong or severe storms will be as they move across the area. Main threats remain damaging winds and possibly some large hail, along with locally heavy rainfall especially over the Upper Cumberland which got quite a bit of rain today. Adjusted pops downward for the rest of the evening hours, but bumped them up overnight based on the latest forecast thinking. Updated products out shortly. && .AVIATION... 00Z TAF DISCUSSION. Scattered showers and thunderstorms are currently impacting northeastern portions of the CWA. These storms will impact KCSV in the next few hours; VFR conditions at all other terminals. Another round of showers and thunderstorms are possible tomorrow morning moving southwestward. Storm should arrive at KCKV by 06Z, KBNA/KMQY by 07Z, and KCSV by 11Z. MVFR cigs and vis are possible during these showers and storms. After these storms, VFR conditions will return to all terminals. && .OHX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION......Shamburger AVIATION........MacDonald
Area Forecast Discussion
National Weather Service Tulsa OK
928 PM CDT Thu May 31 2018 ...UPDATE... .DISCUSSION... A surface boundary remained positioned from far Northeast Oklahoma through far Northwest Arkansas and into Southeast Missouri this evening. Convection continued to develop and push eastward along/near this boundary...with most of activity remaining northwest and west of Northwest Arkansas. A few showers/storms had begun to develop in Madison/Carroll within the past hour along the boundary. Across the rest of Eastern Oklahoma and Northwest Arkansas...mostly clear to mostly cloudy skies and light winds were observed. Overnight tonight...this surface boundary looks to weaken some and shift east- southeast. This will allow for showers and thunderstorms to remain possible across mainly Northwest Arkansas into the overnight hours. Based on latest radar trends compared to latest CAM solutions...have leaned more toward the HRRR for precip tonight. Latest meso- analysis indicated that the cap was beginning to strengthen over the CWA. In response...a limited severe potential with mainly damaging winds and large hail...will remain possible for the next few hours and then look to weaken late tonight as the cap continues to increase over the boundary. Dewpoints currently in the 70s are progged to not change all that much tonight. Thus...with skies varying from mostly clear to mostly cloudy...temperatures look to remain on the warm side with lows in the upper 60s to mid 70s forecast. For the evening update...have adjusted pops/wx to account for the mentioned above as well as add minor tweaks to hourly temp/dewpoint/sky/wind grids based on latest trends and observations. The rest of the forecast seems to be handling well at this time. && .PRELIMINARY POINT TEMPS/POPS... TUL 74 95 78 93 / 10 0 0 10 FSM 75 95 76 96 / 20 0 0 10 MLC 75 94 77 95 / 10 0 0 10 BVO 68 94 75 92 / 10 0 10 10 FYV 68 90 72 90 / 20 10 0 10 BYV 69 91 72 88 / 30 10 10 10 MKO 74 94 76 93 / 10 0 0 10 MIO 69 92 75 91 / 20 0 10 10 F10 74 94 77 94 / 10 0 0 10 HHW 75 94 75 95 / 0 0 0 10 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...Heat Advisory from noon to 8 PM CDT Friday for OKZ054>057- 059>062-064>067-070>076. AR...Heat Advisory from noon to 8 PM CDT Friday for ARZ019-020-029. && $$ SHORT TERM...20 AVIATION.....10