####018005580#### FXUS65 KPIH 250910 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 310 AM MDT Thu Apr 25 2024 .SHORT TERM...Today through Friday Night. Early morning satellite imagery shows three separate H5 lows across the WRN CONUS and NE Pacific which are located across the Desert SW, WRN Canada, and off the PacNW coast respectively. A split H5 trough overhead with the two inland lows and a series of shortwave troughs continue to the main driver of precipitation and instability in our region with that third low off the coast expected to move onshore tonight into Friday. Isolated to scattered showers and thunderstorms today and tonight will increase in areal coverage for Friday as that PacNW low shifts SE into the Great Basin supporting wrap around bands of moisture heading into the weekend. Taking a look at the convective environment for today, the HREF ensemble SBCAPE shows around 200-500 J/kg and 20-30 kts of 0-6km shear with a focus on stronger shear across the Upper Snake Plain and ERN/SRN Highlands. This is where we can expect to see the potential for stronger storms due to a more favorable environment which is in line with the HREF model probability of thunder showing a 60-80% chance for these aforementioned areas. Further west, those probabilities decrease west to east with a 10- 30% chance of thunder in the CNTRL Mountains/Magic Valley region. Stronger storms today will be capable of producing wind gusts in excess of 30 mph, hail up to around nickel to quarter size, and brief moderate to heavy rain. Given the HREF model probability of wind speeds greater than 35 mph remains less than 10% today, the primary hazards today will focus on small to perhaps some larger hail with more organized cells. Winds aloft will also increase today with 700 mb winds around 20-35 kts supporting gusts around 25 to 40 mph across the Snake Plain and Magic Valley region. Winds for these areas will remain elevated heading into the weekend courtesy of continued breezy 700 mb winds. Highs today will be cooler than yesterday in the 50s/60s and will continue that trend into Friday returning back to the 40s/50s. As we end up getting a colder airmass in place for Friday and Saturday, accumulating snow is expected generally above 7000-8000 feet with an emphasis on highest totals in the CNTRL Mountains. This is especially the case in the Lost River, Lemhi, and Beaverhead Ranges where a 10-30% chance of greater than 12 inches of snow exists through Sunday morning across the highest elevations. MacKay .LONG TERM...Saturday through next Thursday. Main impacts Saturday will be continuing showers and thunderstorms with most precipitation expected to be in the Snake River Plain and eastern mountains. Very high probability of over a tenth of an inch in those areas on Saturday with much lower chances of wetting rains further northwest in the central mountains. It will dry west to east Saturday night but showers and thunderstorms will continue mainly in the eastern mountains once again Sunday afternoon with lesser chances further west. It will be very cold Saturday with highs only in the 40s and 50s with widespread cloud cover and showers and thunderstorms limiting much rise. It will moderate to near normal Sunday with highs mainly in the 40s and 50s mountains and 50s to lower 60s in low elevations. Temperatures will warm considerably next week with much lower chances of precipitation Monday through Thursday with only a slight chance of precipitation. Highs in low elevations will be well into the 70s by Wednesday and Thursday. With a fairly strong westerly zonal flow aloft expect breezy to windy conditions Monday through Thursday with the warmer temperatures. GK && .AVIATION...For the 12Z TAFS through 12Z Friday. Another short wave moving through eastern Idaho today will continue chances of showers and thunderstorms mainly this afternoon but will also see some activity this morning. Have a variety of vicinity showers and thunderstorms at all sites through the day. Ceilings will remain VFR and wind speeds at BYI, PIH, and IDA will rise to 10 to 15 knots sustained and 20 to 25 knot gusts later this morning and afternoon. DIJ is the best chance to see sustained showers today. Will continue to have showers and thunderstorms on Friday. GK && .HYDROLOGY... Water levels remain elevated on the Portneuf River in Pocatello and Topaz where River Flood Warnings and River Flood Advisories remain in place respectively until further notice. Minor to moderate flooding is expected or ongoing in these areas with both locations forecast to crest this weekend before dropping slightly heading into early next week. Further north and west along the Snake River, water managers have increased releases from upstream reservoirs leading to high flows in excess of 10,000 cfs downstream from Palisades to Milner. The Snake River near Heise gauge has also reached action stage and is forecast to be at that stage until further notice due to releases from Palisades. Willow Creek below Tex Creek above Ririe Reservoir and the Blackfoot River above Blackfoot Reservoir both also continue to be in action stage since Monday with no major impacts seen elsewhere in our CWA as of Thursday morning. MacKay && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$ ####018007439#### FXUS64 KLUB 250911 AFDLUB Area Forecast Discussion National Weather Service Lubbock TX 411 AM CDT Thu Apr 25 2024 ...New SHORT TERM, LONG TERM, FIRE WEATHER... .SHORT TERM... (Today and tonight) Issued at 410 AM CDT Thu Apr 25 2024 Current satellite midlevel water vapor imagery shows the upper trough over southern Cali this morning with moist southwesterly flow bringing in a plume of high clouds across the area. At the surface, low clouds have begun to develop across the Texas Panhandle and will filter southward through the early morning hours. Southeasterly surface flow will also usher in low clouds from the south, which will fill in a stratus deck across the area by morning. A combination of these low and high clouds are expected to linger through much of the morning hours before clearing from west to east. A lee low will develop across eastern Colorado today, with a dryline extending southward across West Texas. Most of the models have the dryline positioned from north to south along the I-27 corridor (give or take about a 30 mile buffer east or west). Low 60s dewpoints east of the dryline will give way to plenty of low level moisture. Instability will be present during the afternoon hours with MLCAPE values in excess of 2000-2500 J/kg. Winds aloft will still be on the weaker side as the upper jet doesn't approach the area until the evening hours, thus effective bulk shear values will reside around 30-40 knots. One of the biggest caveats to thunderstorm development this afternoon is the cloud cover. Several models have the clouds lingering through most of the afternoon with limited daytime heating and too strong of convective inhibition. If clouds clear and convective temperatures can be reached along or east of the dryline in the afternoon hours tomorrow, a severe storm capable of very large hail, damaging winds and a tornado cannot be ruled out. Uncertainty remains high and therefore PoPs were trimmed to slight chance across mostly the far southeast Texas Panhandle and northern Rolling Plains where the environment may be able to overcome the capping inversion with just in time daytime heating. The threat for severe weather increases around sunset as the right entrance region of the upper jet passes over the forecast area and the dryline sharpens. Instability values increase with MLCAPE values approaching 3000 J/kg as a surge of 850mb theta-e enters the Rolling Plains. In addition, the low level jet will begin to increase as well with effective bulk shear values in excess of 60-70 knots. An isolated supercell or two may develop initially along the dryline in the late evening hours (~10-11pm) with very large hail, damaging wind gusts and a tornado or two possible. The Pacific front will be racing eastward late this evening and therefore any isolated storms will rapidly grow upscale and linear with the main threat becoming damaging wind gusts. The setting sun and loss of daytime heating will also lead to storms becoming elevated and the potential for tornadoes diminishing. However, a spin up along the line of storms cannot be completely ruled out with the presence of the cranking low level jet and slight backing of the southerly surface winds. Storms will quickly move eastward with the Pacific front as storm motions are around 50 to 60 knots. Thus any thunderstorm chances will be out of the Rolling Plains by the early morning hours tomorrow. && .LONG TERM... (Friday through Wednesday) Issued at 410 AM CDT Thu Apr 25 2024 Relatively zonal flow aloft will prevail Friday as the upper level low over the Central Plains continues to lift to the northeast while an secondary upper level low tracks into the Four Corners region. This will allow pleasant warm and quiet weather conditions Friday with high temperatures in the upper 70s to mid 80s under clear skies. The upper level low across the Four Corners region will begin to track eastward through the early morning hours Saturday allowing the surface low across the TX/OK Panhandles to amplify, tightening the gradient, which may lead to wind advisory level southwesterly winds around 30 to 35 mph and patchy blowing dust across areas on the Caprock Saturday. The dry-line will also make its return Saturday morning, however; given strong southwesterly winds through the day we can expect the dry-line to remain fixated across our far eastern column of counties. Regardless of the ensembles hinting at the possibility of showers and thunderstorms developing along the dry-line Saturday afternoon; lack of moisture return, lingering cloud cover, and instability aloft projected farther east may prohibit convective initiation. The upper level low will quickly eject to the northeast by Sunday morning swinging a cold front through the forecast area during the early morning hours on Sunday. This will shift winds out of the northwest where they will remain breezy throughout the day. Sadly this front will not do too much in the way of temperatures with highs in the 70s and 80s expected. Flow aloft will become more zonal by Sunday evening as upper level ridging begins to build back into the region with quiet and dry weather expected for the beginning of next week. Ensembles are continuing to hint at our next disturbance in the flow aloft next Wednesday. A lot of this will vary upon how much moisture return we will see across the forecast area Tuesday and Wednesday as surface winds shift out of the south. Nonetheless will continue with NBM slight chance PoPs for the time being, given the vast amount of uncertainty with the evolution of this system. && .AVIATION... (06Z TAFS) Issued at 1240 AM CDT Thu Apr 25 2024 Low clouds will move in again tonight at all three TAF sites with most likely MVFR ceilings, but brief IFR ceilings may occur. Clouds will clear through the afternoon with the return of VFR sky conditions. Winds will increase through the day with 15 to 25 knot southerly surface winds through the afternoon and evening hours. There is a small chance for thunderstorms to develop late tomorrow night near LBB, but confidence was too low on exact location at this time. The storms may develop just east of the TAF site and then are expected to continue moving quickly eastward. && .FIRE WEATHER... Issued at 410 AM CDT Thu Apr 25 2024 Critical fire weather conditions are possible this afternoon across the far southwest Texas Panhandle and western South Plains. Very dry conditions will persist west of the dryline with minimum relative humidity values dipping into the single digits. Southwest surface winds will increase this afternoon to around 20 to 30 mph with gusts up to 40 mph possible with the approaching upper trough and strengthening lee low across eastern Colorado. Clearing clouds will give way to temperatures warming quite nicely across this area of concern with highs in the mid to upper 80s. && .LUB WATCHES/WARNINGS/ADVISORIES... Red Flag Warning from 1 PM this afternoon to 10 PM CDT this evening for TXZ021-022-027-028-033-034-039. && $$ SHORT TERM...11 LONG TERM....12 AVIATION...11 ####018006736#### FXCA62 TJSJ 250912 AFDSJU Area Forecast Discussion National Weather Service San Juan PR 512 AM AST Thu Apr 25 2024 .SYNOPSIS... Wet and unstable weather conditions are expected to prevail for the next few days with limited to elevated risks of flash flooding, urban and river flooding, and landslides mainly over the interior, western, and northern Puerto Rico, as well as the San Juan metro area. A slight improvement on weather condtions is expected by Saturday night into Sunday as drier air filters into the local area. && .SHORT TERM...Today through Saturday... Isolated to scattered showers affected the eastern third of Puerto Rico and smaller islands during the night hours. However, most of the activity remained over the Caribbean waters. Radar estimates indicated up to 0.60 inches of rainfall fell mainly over and near El Yunque. Similar activity is expected for the rest of the morning hours over windward coastal areas. According to the Tropical Analysis and Forecast Branch (TAFB) surface analysis, the axis of the surface trough that has been over the CWA for the past few days will finally move northwestward today. However, plenty of columnar moisture, combined with diurnal heating and local effects, along with marginal instability aloft, will promote another active afternoon. Model guidance suggests that the bulk of the activity will be clustered a bit further north than the previous day steered by southeast to east-southeast winds. Nonetheless, heavy showers and thunderstorm activity will generally be observed in already saturated soils and areas with elevated streamflows. While the overall wet and unsettled weather pattern will persist for the remainder of the short-term forecast, some changes have been suggested by the latest model cycle for Friday and Saturday. Late tonight through early Friday, we could observe a slight decrease in showers, mostly across the eastern CWA, as a slot of slightly drier air moves in. However, this respite won't last long as the pre- frontal trough currently affecting the Dominican Republic will gradually move over the local area by Friday, increasing low-level instability and moisture convergence over the region. Meanwhile, a mid-level short-wave trough will strengthen and pass over the northeastern Caribbean, further enhancing the potential for deep convective activity. Therefore, another afternoon with widespread activity is expected on Friday. By Saturday, previous model cycles indicated a drying trend, which was expected to limit the areal coverage of convective activity across the area. However, the latest model cycle now suggests a prolongation of above-normal moisture across the islands. The GFS Galvez Davison Index suggests the potential for isolated to scattered thunderstorms and heavy rainfall on Saturday afternoon, delaying the transition to a more stable weather pattern. Additionally, cold air advection at mid-levels will be high, with 500 mb temperatures falling between -8 and -9 degrees Celsius. This will enhance low- to mid-level lapse rates and increase the potential for strong thunderstorms capable of producing frequent lightning and gusty wind conditions. Overall, expect a wet and unstable weather pattern throughout the short-term forecast, with limited to elevated risks of flooding and lightning across the area, particularly over interior, western, and northern Puerto Rico, as well as the San Juan metro area. Urban and river flooding, flash flooding, and landslides will continue to impact areas already affected in the past week. Please continue to monitor the forecast in the next few days and pay attention to any advisories or warnings that our office may issue. .LONG TERM...Sunday through Thursday... A strong surface high pressure moving off the eastern coast of the united states, is expected to promote moderate to locally fresh northeast winds at the beginning of the long-term period. The latest model guidance have changed, delaying the departure of the moisture from the local area. However, by Sunday remnant moisture from a surface trough and old frontal boundary will be pushed south of the region, improving gradually the local weather. Variable weather conditions are expected from Sunday through Tuesday, with passing showers over the east coast of Puerto Rico and the U.S. Vrigin Islands. Then, followed by afternoon convection across the southwest portions of PR due to the combination of daytime heating and local effects. Precipitable water values will remain between 1.40 to 1.50 inches through Tuesday night. By Wednesday, a patch of very dry air will filter into the region, limiting the potential of shower activity across the islands. However, this fair weather pattern will not last long due to the arrival of a big field of moisture pulled from South America toward the eastern Caribbean region on early Thursday. A wet and unsettled pattern is anticipated with an elevated potential of showers and thunderstorms across the local area. The general wind flow will be from the northeast then veering from the east southeast by Thursday. Daytime temperatures will remain in the mid 80s along the coastal and urban areas of Puerto Rico and the U.S. Virgin Islands, and from the mid to upper 70s across the Cordillera Central. && .AVIATION... (06Z TAFs) Expc mainly VFR conditions across all terminals through the forecast period. However, areas of SHRA and SCT TSRA this aftn could produce tempo MVFR/IFR conds and mtn obsc, particularly ovr TJBQ/TJSJ aft 25/17z. VCTS/SHRA at TJPS for the most part. ESE winds reaching speeds of up to 8-12 knots, accompanied by higher gusts and sea breeze variations aft 25/13z. && .MARINE... A small northwesterly swell is expected to spread across the local waters today. Showers and thunderstorms will continue to affect the local waters for the next few days. Another surface trough will strengthen the easterly winds from today into Friday, before becoming northeast on Saturday under the influence of a surface high pressure moving off the eastern coast of the United States. && .BEACH FORECAST... Breaking waves of around 3 feet will maintain the risk of rip currents generally moderate for the northern beaches of the local islands. && .SJU WATCHES/WARNINGS/ADVISORIES... PR...None. VI...None. AM...None. && $$ SHORT TERM...CVB LONG TERM....GRS ####018003326#### FXUS65 KRIW 250912 AFDRIW Area Forecast Discussion National Weather Service Riverton WY 312 AM MDT Thu Apr 25 2024 .KEY MESSAGES... - Widespread showers and a few thunderstorms will overspread the state today. Best chances for accumulation remain across western WY. - Second system moves across the state later Friday and continues through the weekend. Ample rainfall accumulations for lower elevations and some snow accumulations at highest mountain peaks. && .DISCUSSION... Issued at 250 AM MDT Thu Apr 25 2024 The midlevel trough continues to push inland across the Four Corners Region, and will sweep across Colorado this evening. This will draw a cold front southeastward across the state today, bringing some sfc focus to the increased moisture across the state. Widespread showers will continue across the state, with some embedded thunder at times this afternoon. Best rain accumulations will be across the western portions this afternoon. Friday the trough will be deepening across the Northern Plains, keeping the ample moisture wrapped around the backside across WY. The next trough will be dropping in from the NW across the northern Rockies, bringing another batch of instability. Models continue bring better precipitation amounts across the state due to multiple lifting mechanisms, but with some deviation in models on overall precip amounts and trouble with the previous several storms, have kept some of the highest QPF amounts in check for the state. Still expecting at least a half inch of rain for all locations except the Bighorn Basin and Johnson County, with areas of central WY likely seeing around 1 inch by late Sunday. Snowfall amounts remain adequate for the higher elevations, with highest accumulation remaining limited to the highest elevations of the Winds. && .AVIATION /06Z TAFS THROUGH 06Z FRIDAY/... Issued at 949 PM MDT Wed Apr 24 2024 Isolated rain showers will linger tonight into Thursday morning, but by Thursday afternoon convection will develop/become widespread. The chance of any terminal having a thunderstorm move directly over it is too low for prevailing TS at this time, but the chance is high enough for VCTS at KJAC from 19Z-00Z Thursday afternoon. Have prevailing VFR at all terminals through the TAF period, but brief reductions to MVFR are possible (20-30%) if a thunderstorm directly impacts a terminal. Most terminals have prevailing VCSH Thursday afternoon as scattered showers and thunderstorms pass through the area. Gusty erratic wind will occur with thunderstorms and thunderstorm outflow boundaries. Wind gusts at high as 40 mph will be possible with thunderstorms. Tonight an area of -RA is likely (60-70%) to be near KLND/KRIW from 06Z-10Z, so have VCSH to account for this, but some -RA is certainly possible (30%). Mountain obscuration will occur at times as BKN040- BKN100 CIGS continue across the area over the next 24 hours. Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts. && .RIW WATCHES/WARNINGS/ADVISORIES... None. && $$ DISCUSSION...Straub AVIATION...Rowe ####018004365#### FXUS61 KCAR 250915 AFDCAR Area Forecast Discussion National Weather Service Caribou ME 515 AM EDT Thu Apr 25 2024 .SYNOPSIS... Low pressure will exit across the Maritimes today. High pressure will build across the region later today into Saturday. A warm front will approach from the southwest Sunday and move to the Saint John Valley on Monday. && .NEAR TERM /THROUGH TONIGHT/... Surface/upper level low pressure will exit across the Maritimes today. A disturbance rotating around the upper low will clip the region early today. The disturbance could bring scattered flurries to northern portions of the forecast area this morning. Otherwise, high pressure will build across the region later today through tonight. Expect partly/mostly sunny skies north, sunny Downeast, today. The pressure gradient between the exiting Maritimes low and building high pressure will support gusty northwest winds today. Wind gusts of 30 to 35 mph are expected through early this afternoon, then decreasing late. Mostly clear skies are expected across the region tonight. High temperatures today will range from around 40 to the lower 40s north, to the mid to upper 40s Downeast. Low temperatures tonight will range from the upper teens to around 20 north, to the lower to mid 20s Downeast. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... Upper level trof axis will be exiting east across the Canadian Maritimes during Friday. Deep layered northwest flow of dry air remains in place through the afternoon under mainly sunny skies. Afternoon highs will top out around the 50 degree mark across the north and the low to mid 50s for Bangor and Downeast. Upper trof continues to exit to the east with rising heights as upper ridging begins to build in. Surface high slides across the region with mainly clear skies and light winds. Radiational cooling conditions should allow for overnight lows falling into the mid to upper 20s. Upper level ridge builds east toward the region on Saturday as surface high slides east. Expect another mainly sunny day with milder afternoon high temperatures. Developing onshore flow will keep afternoon highs several degrees cooler for the immediate coast and outer islands. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Saturday night should remain dry as upper ridging and dry air remains in place. Any showers in advance of a weakening short wave and warm front from the west should hold off until later Sunday afternoon. A cold front will then begin to move into far northern areas later Sunday night and then tend to dissipate across the area during Monday. Low pressure will track northeast toward James Bay during Monday drawing a warm front toward the region, along with the chance of late night showers. An occluded front will cross the region later Tuesday through Wednesday with the chance for showers, or even perhaps a steadier rain. Afternoon high temperatures will tend to average a bit above normal for this time of year. && .AVIATION /09Z THURSDAY THROUGH MONDAY/... NEAR TERM: Local MVFR conditions possible across northern areas this morning with scattered flurries. Otherwise, VFR across the region today through tonight. Northwest winds 10 to 20 knots with gusts up to around 30 knots through early this afternoon, then decreasing to 10 to 15 knots with gusts up to 25 knots later this afternoon. Northwest winds 5 to 10 knots tonight. SHORT TERM: Friday through Saturday night...VFR conditions expected. NW wind 10 to 15 kt on Friday, light and variable Friday night, then becoming light SE Saturday and Saturday night. Sunday through Monday...VFR/MVFR. && .MARINE... NEAR TERM: A Small Craft Advisory remains in effect for all the waters through 2 PM. Winds/seas then below small craft advisory levels later this afternoon through tonight. SHORT TERM: Winds/seas are expected to remain below SCA levels through the period. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...None. MARINE...Small Craft Advisory until 2 PM EDT this afternoon for ANZ050>052. && $$ Near Term...Norcross Short Term...TWD Long Term...TWD Aviation...Norcross/TWD Marine...Norcross/TWD