Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 07/02/16

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
441 PM AKDT FRI JUL 1 2016

.ANALYSIS AND UPPER LEVELS...
The upper level low remains over the Gulf of Alaska, but is
beginning to show signs of moving east. The strong short-wave
system on the northwest side of the low that provided last nights
rainfall to south central Alaska is now in southwest Alaska. There
is an upper level low over the southwest Bering Sea as well as the
western and central Aleutians. This low has stalled and is
continuing to weaken. A weather front associated with this low
stretches from about Nikolski northwestward across the Bering
Sea. A ridge of high pressure separates these two low, with the
"col" over the far eastern Bering.

&&

.MODEL DISCUSSION...
The numerical models are in reasonable agreement on the over-all
pattern. There continue to be some differences in the timing,
location, and strength of various short-waves surrounding the
Gulf low. There are also some minor differences in the handling
of precipitation, especially in regards to convection. Therefore
the forecast confidence is slightly below normal.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2...Sat and Sun)...
Afternoon mountain showers and diurnal sea breezes will be the
story for the weekend. The easterly wave that brought a third to
an inch and half of rain across Southcentral has cleared through
most of the area. The Alaska Range has slowed its westward
progress keeping some rain falling over Kachemak Bay. It will
pivot through this corridor on Sat bringing rain to parts of
Kodiak Island later tonight through the Sat morning hours.
Meanwhile...the rest of the area will remain in very light flow
with generally moist and unstable conditions. With all the recent
rainfall...many places could see some patchy fog or low stratus
develop overnight. But this should dissipate relatively quickly on
Saturday as some sun breaks through. Showers should develop along
the mountains in the afternoon, but with weak steering flow, we
don`t expect many of them to make it into valleys. The best
instability remains farther north over the Alaska Range and parts
of the Talkeetna Mountains, so can`t rule out an isolated
thunderstorm developing on those higher peaks. Sun looks very
similar to Sat with minimal change to the pattern. The leftover
band of rain near Kodiak should move off into the Gulf making for
drying conditions there.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
The Gulf low that has been relatively stationary the last couple
of days will finally push off to the east tonight. This will
change the easterly flow over the area to be more northerly which
will help to diminish showers over the area. The majority of the
rain remaining by the beginning of next week will be in the more
eastern parts of Southwest Alaska like the Alaska and Aleutian
Ranges.

Even though the main upper level low is departing there are still
more shortwaves moving through the area with the strongest one
coming through this evening. It will track south from the
Kuskokwim Valley towards Bristol Bay and will help to initiate
thunderstorms in the area. There will also be enough instability
over the Kuskokwim Valley for possible afternoon thunderstorms
Saturday and Sunday.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
The broad area of low pressure over the Western Aleutians will
track slowly east over the weekend. It looks to bring light rain
to the Aleutians with some making it to the Pribilof Islands on
Saturday. By the beginning of next week the broad upper level low
will be absorbed into a broad trough extending across the Bering
from the north. This trough will keep light rain over the Bering
and Aleutians.

&&

.LONG TERM FORECAST (Days 3 through 7)...
The upper level pattern will begin to shift by the end of this
weekend to a more stable pattern, as the upper low shifts further
east and weak high pressure aloft builds in from the west. Thus,
with everything being weak, any precipitation that develops Sunday
over southern mainland Alaska will be mostly scattered and weak.
The persistence of a mid-level unstable layer over much of the
area will result in some diurnal showers mainly along the
mountains.

For the Independence Day holiday, a strong upper level trough will
dig southward across the eastern Bering. Ridging will build east
of it across the Gulf. However, the models are in disagreement
with how quickly the ridge builds, and where the trough axis sets
up over the Bering. Currently, the models agree enough for the
4th of July to suggest a return to southwesterly winds in the
upper levels. Since the disturbances depicted in the models all
remain weak, the weather looks similar to Sunday at this point for
much of mainland Alaska.

Active weather should persist for much of southern Alaska into
midweek as the trough over the Bering moves into mainland Alaska.
However, the model differences and associated forecast
uncertainty only compound with time concerning how quickly and in
what form (open trough or cutoff low), the troughing moves east.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...BL
SOUTHCENTRAL ALASKA...MO
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...TP



  [top] Southeast Alaska Forecast Discussion National Weather Service Juneau AK 324 PM AKDT FRI JUL 1 2016 .SHORT TERM...A low just west of Sitka this afternoon continues to track north along the outer coast. Visible and WV satellite imagery is clearly depicting the circulation, but it is not nearly as evident in IR imagery. Radar has been showing banding in the returns, but the total system is slightly stronger than originally expected and had produced 30 kts of wind in Clarence Strait earlier today. Morning model runs still showing some divergence on the low center. With the system so close to the outer coast, minor differences in location, track, and intensity can have significant impacts in the forecast. That said, opted for the NAM for updates to pressure and winds today. Resulting changes primarily affect the winds over the eastern gulf and coastal locations north of Cape Decision. On the inside, result was to increase winds speeds a bit, so the afternoon forecast features small craft advisories for several of the inner channels. Clarence Strait is expected to continue at high end small craft intensity through the evening before relaxing. A low approaching the Dixon Entrance from the southwest tomorrow will produce another round of small craft winds out of the east tomorrow afternoon, but these winds will be mostly over southern areas near the Dixon Entrance. Small craft southerlies will get into the ocean entrances of Chatham Strait and Sumner Strait early this evening but should diminish to 15 kts or so by tomorrow morning. Also expect small craft winds out of the east over eastern portions of Sumner and southeasterlies to 25 kts along Frederick Sound south of Cape Fanshaw. Later tonight, max winds on the inside will shift north to include Stephens passage north of Taku inlet, the northern portions of Chatham Strait, and much of Icy Strait. Finally, easterly Small Craft winds to 30 kts from late this evening through tomorrow afternoon are forecast for Cross Sound. Small craft winds on the outside will progress from south to north as well, ending late morning as the low weakens and fills vicinity of Cape Fairweather. POP forecast from last night still looks good, so no changes there. Did update QPF using a blend of Canadian REG and NAMDNG. Overall forecast confidence is average to below average due to uncertainties in how inner channel winds will respond to the low off the coast. .LONG TERM...The low passing through Dixon Entrance Saturday night will keep showers largely confined to the southern panhandle. An upper level low shifts south Saturday night then looks to settle over central BC Sunday. This will also help to clear away showers initially over the north, but then once its in Canada may cause clouds and some showers to move in from the east. For this reason chance/slight chance of showers remain in the forecast over the weekend. Weak ridging will develop over the gulf starting Monday, or a better way to describe it, zonal onshore flow. This leads to a chance of rain in the forecast, or at least a bit more cloud cover. There are some indications that a marine layer could develop over the gulf under the ridge, this will be monitored over the next couple days. If an inversion develops or there is a low cloud deck that would be of concern for Monday night activities along the outer coast. Adjusted temps up slightly through the extended forecast as both base models and bias corrected models were warmer. Thinking that sunny breaks in the clouds will allow for more seasonable highs in the mid 60s. Used an ensemble approach for updates today. Model agreement on pressure was good through the mid range then diverged day 6, used more WPC guidance for later periods. Model differences on the POP forecast were still fairly high over the holiday, so still lower confidence in that part of the forecast. && .HYDROLOGY...Early afternoon indications are that Suicide Basin may have emptied out. The lake, however, will continue to rise through the evening, with a forecast crest of at or near 12 feet later tonight. See the flood warning issued by NWS Juneau for details and be careful and vigilant around flood waters. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ021-022-031>036-041>043. && $$ Fritsch/Ferrin Visit us at http://www.weather.gov/Juneau
Southeast Alaska Forecast Discussion National Weather Service Juneau AK 324 PM AKDT FRI JUL 1 2016 .SHORT TERM...A low just west of Sitka this afternoon continues to track north along the outer coast. Visible and WV satellite imagery is clearly depicting the circulation, but it is not nearly as evident in IR imagery. Radar has been showing banding in the returns, but the total system is slightly stronger than originally expected and had produced 30 kts of wind in Clarence Strait earlier today. Morning model runs still showing some divergence on the low center. With the system so close to the outer coast, minor differences in location, track, and intensity can have significant impacts in the forecast. That said, opted for the NAM for updates to pressure and winds today. Resulting changes primarily affect the winds over the eastern gulf and coastal locations north of Cape Decision. On the inside, result was to increase winds speeds a bit, so the afternoon forecast features small craft advisories for several of the inner channels. Clarence Strait is expected to continue at high end small craft intensity through the evening before relaxing. A low approaching the Dixon Entrance from the southwest tomorrow will produce another round of small craft winds out of the east tomorrow afternoon, but these winds will be mostly over southern areas near the Dixon Entrance. Small craft southerlies will get into the ocean entrances of Chatham Strait and Sumner Strait early this evening but should diminish to 15 kts or so by tomorrow morning. Also expect small craft winds out of the east over eastern portions of Sumner and southeasterlies to 25 kts along Frederick Sound south of Cape Fanshaw. Later tonight, max winds on the inside will shift north to include Stephens passage north of Taku inlet, the northern portions of Chatham Strait, and much of Icy Strait. Finally, easterly Small Craft winds to 30 kts from late this evening through tomorrow afternoon are forecast for Cross Sound. Small craft winds on the outside will progress from south to north as well, ending late morning as the low weakens and fills vicinity of Cape Fairweather. POP forecast from last night still looks good, so no changes there. Did update QPF using a blend of Canadian REG and NAMDNG. Overall forecast confidence is average to below average due to uncertainties in how inner channel winds will respond to the low off the coast. .LONG TERM...The low passing through Dixon Entrance Saturday night will keep showers largely confined to the southern panhandle. An upper level low shifts south Saturday night then looks to settle over central BC Sunday. This will also help to clear away showers initially over the north, but then once its in Canada may cause clouds and some showers to move in from the east. For this reason chance/slight chance of showers remain in the forecast over the weekend. Weak ridging will develop over the gulf starting Monday, or a better way to describe it, zonal onshore flow. This leads to a chance of rain in the forecast, or at least a bit more cloud cover. There are some indications that a marine layer could develop over the gulf under the ridge, this will be monitored over the next couple days. If an inversion develops or there is a low cloud deck that would be of concern for Monday night activities along the outer coast. Adjusted temps up slightly through the extended forecast as both base models and bias corrected models were warmer. Thinking that sunny breaks in the clouds will allow for more seasonable highs in the mid 60s. Used an ensemble approach for updates today. Model agreement on pressure was good through the mid range then diverged day 6, used more WPC guidance for later periods. Model differences on the POP forecast were still fairly high over the holiday, so still lower confidence in that part of the forecast. && .HYDROLOGY...Early afternoon indications are that Suicide Basin may have emptied out. The lake, however, will continue to rise through the evening, with a forecast crest of at or near 12 feet later tonight. See the flood warning issued by NWS Juneau for details and be careful and vigilant around flood waters. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ021-022-031>036-041>043. && $$ Fritsch/Ferrin Visit us at http://www.weather.gov/Juneau
  [top] Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 303 PM AKDT FRI JUL 1 2016 .SYNOPSIS... Aloft... A ridge stretching east to west across northern Alaska will persist through the weekend then retreat east in NW Canada next week as a trough develops over the Bering Sea. A low aloft in the Gulf of Alaska will move over SE Alaska Sat and then move slowly east. A series of short wave troughs rotating around this low will move west across Interior Alaska bringing bands of showers and isolated to scattered thunderstorms to the eastern and southern Interior through the weekend. A strong short wave that now lies from Denali to Livengood to Old Crow will move to McGrath to Tanana to Arctic Village by 4am Sat...and then weaken in place through Sun. There is a wide band of showers NW of this trough that becomes scattered north of the Yukon River. This dropped .10 to .25 inch of rain over the eastern Interior south of Circle with up to .50 inch in the hills north of Fox and east of Delta Junction. Expect this to drop another .50 to 1 inch over zones 221 225 and 227 through Sat with the heaviest amounts in Denali Park. From .50-1.5 inch of rain has already fallen in Denali Park so this will keep small stream and rivers there high through the weekend and could still cause mud and rock slides. A second and weaker short wave trough near Old Crow will move to Fort Yukon by 4am Sat...to Denali to Livengood by 4pm Sat...and then slowly dissipate through Sun. This will cause scattered showers and scattered PM thunderstorms in eastern zone 216 western 221 and 227 Sat and into Sun. The thunderstorms could have small hail Sat. A third short wave trough over the southern Yukon Territory will move to the ALCAN Border by 4pm Sat and then weaken over the eastern Interior through Sun. This will bring more widespread showers to zones 224 226 Sat into Sun and keep scattered showers and at least isolated thunderstorms going in the remainder of the eastern Interior. There is the potential for hail again Sun and this will need to be watched. A fourth short wave is expected to move to the extreme SE interior Sun night and Mon and could bring heavy rain...but this still has a lot of uncertainty. Surface... An Arctic warm front from Barter Island to Deadhorse will move to Barter Island north by 4am Sat then move north of the coast. Expect fog to reform along this front tonight and then move offshore Sat. A 1022 mb high over the central Bering Sea will weaken slowly through Sun. An Arctic cold front in the western Chukchi Sea will move east to Barrow to Cape Lisburne then west by 4pm Sat...to Deadhorse to a 1007 mb low near Point Hope by 4am Sun...and then quasi- stationary. Fog and a chance of rain will accompany the front. Westerly flow will increase south of the low center and should return widespread fog to the southern Chukchi and north Bering Seas and most of the West Coast of AK by Sat night. && .DISCUSSION... Models are similar on the large scale flow pattern and features but differ some on timing and location of weak short wave troughs moving west across the Interior. Since these weak short wave troughs are the main force driving convection over the interior the location is important. We favor the GFS locations of the short waves and heavy rain through Sat night Sun and then the flow becomes so weak that we can really only deal with short wave location and accompanying rainfall in a probabilistic sense. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Continued wet across southern and eastern Interior with drier and warmer conditions in the northwest Interior. Expect isolated thunderstorms a a few lightning strikes today and Sat...except LAL 3 Sat in eastern Zone 216...western 221 and 227. Sun could see LAL 3 over the eastern Interior but uncertain at this point so left it as LAL 2 for Sun. && .HYDROLOGY... The past 36 hrs saw .10 to .25 inch of rain fall over the eastern Interior south of Circle with up to .50 inch in the hills north of Fox and hills east of Delta Junction...while Denali Park had between .50-1.5 inch. Expect another .50 to 1 inch over zones 221 225 and 227 through Sat with the heaviest amounts in Denali Park. This will keep small stream and rivers in Denali high through the weekend and could cause mud and rock slides through the weekend. There is a potential for heavy rain in zones 224 and 226 SE of Tok Sun night and Mon but still much uncertainty on this. && .AFG WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory for PKZ245. && $$ JB JUL 16
Southeast Alaska Forecast Discussion National Weather Service Juneau AK 533 AM AKDT FRI JUL 1 2016 .SHORT TERM...The biggest story over the next 24 hours is the ongoing glacial dam release from Suicide Basin into Mendenhall Lake and River. This will be covered further in the hydrology section below. As for the weather, the main feature is a 1000 mb low pressure system currently in the southeast gulf which will gradually weaken while moving north to near Cape Fairweather by late tonight. A secondary wave of low pressure will develop southwest of Haida Gwaii late tonight but is expected to remain south of the area. Stratiform rainfall is currently ongoing across the southern half of the panhandle aided by warm air advection in association with the advancing low. This will continue to spread northward through the day reaching the Juneau area this morning and the far northern panhandle this afternoon. Precipitation chances will remain high throughout the next 24 hours across all of Southeast Alaska. Expecting rainfall totals to generally range from one half of an inch to an inch with heaviest amounts over the southern panhandle. This system will enhance winds over the southern half of the area but am only expecting 10 to 20 mph for the land areas and 20-25 kt for the inner channels. Decreased winds across the far northern panhandle as a parallel pressure gradient to Northern Lynn Canal will lead to lighter winds. Used the 06z NAM and Hi-Res model guidance for updates to the short term period. Forecaster confidence is above average. .LONG TERM...Through the weekend, generally a zonal flow pattern in place across the north Pacific aloft. The closed low at 500 mb over the Gulf of Alaska weakens and moves into western Canada Monday while a broad weak ridge aloft forms over the western gulf. Weak to null flow aloft over the northern panhandle will be in place headed into early next week. Long range trend for Southeast Alaska looks to be for a development around mid week to the end of the week over the gulf. A surface low near Cape Fairweather is weakening, while a low moving across the southern gulf along 50N and then curving north across Haida Gwaii on Saturday. This will spread rain into the southern half of the panhandle. Saturday evening the low will move into British Columbia while the low off of Cross Sound dissipates. The surface pattern across the gulf Friday into Saturday becomes west to northwest. The potential for low probability showers from onshore flow will exist along the outer coast Sunday into Monday. With the main flow pattern to the south of the forecast area not expecting a significant weather system for the next few days. && .HYDROLOGY...Suicide Basin has released and a flood warning is in effect for Mendenhall River and Lake until Saturday morning. The current forecast crest of 11.6 feet is close to the previous record value of 11.85 feet set in 2014. As of early this morning, Mendenhall Lake had risen to a stage of 8.5 feet and the rate of rise is steadily increasing as expected. The level in Suicide Basin continues to fall rapidly. Residents near the lake or the river should remain alert and keep track of updates to this event as they are issued by NWS Juneau. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ033>036-041>043. && $$ TPS/Bezenek Visit us at http://www.weather.gov/Juneau
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 447 AM AKDT FRI JUL 1 2016 .ANALYSIS AND UPPER LEVELS... Upper level lows are over the western Bering and the southern Gulf of Ak this morning with the jet remaining well south of the forecast area. At the surface, lows are near Attu and over the eastern Gulf. A ridge of high pressure is over the eastern Bering. The thermal trough/theta-e ridge is draped along the Alaska and Aleutian ranges and is serving as the focus for showers and even a few nocturnal thunderstorms. && .MODEL DISCUSSION... Models remain in agreement that the Gulf upper low will slowly rotate its way into British Columbia by Sun morning. Easterly waves moving along the northern flank of the low will interact with the moisture rich thermal trough/theta-e ridge through the weekend. This may explain what is happening, but these waves are poorly timed in model solutions, so exactly when precipitation initiation and enhancement will occur remains a problem. The forecast utilizes some Nam and GFS in an attempt to pinpoint some of the precipitation events. In the west the surface low will drift and weaken over the western Aleutians through the weekend. A weak associated front will move to the central Aleutians during the same period. Again the Nam and GFS were utilized in the forecast. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... The last of a series of fairly strong short-waves crossing westward across Southcentral Alaska this morning will exit to Southwest Alaska this afternoon bringing an end to widespread showers and rain. However, as the large upper low over the Gulf tracks eastward today and tonight, short-waves tracking across Southwest Alaska will rotate southeastward across Kodiak Island and the western Gulf bringing widespread showers to that region. In the wake of the upper level low the flow across the region will become more and more chaotic, with weak impulses wandering around. This creates a lot of uncertainty in the forecast. Have used a broadbrush approach to the precip forecast for tonight through Saturday night. In this scenario would expect more showers during the afternoon and evening hours focused along the mountains. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... Clouds, rain, and thunderstorms will be the focus for Friday and Saturday. Widespread showers with embedded thunderstorms will encompass the Kuskokwim Valley southward through Greater Bristol Bay today. A lesser chance exists over the Kuskokwim Delta, but afternoon showers and a slight chance for thunder are possible. Nearly the same conditions are on tap for Saturday, however, any thunderstorms will stay confined to the Kuskokwim Valley along the Alaska Range. For the Delta, most of the shower activity will be east of Bethel along the Kilbucks. Winds will be on the lighter side everywhere, and temperatures will be well above average for this time of year. Technically speaking...A large upper level low in the gulf controls the pattern, but the real action is rotating around the circulation in the form of embedded easterly shortwaves. Feeding on the baroclinity from the difference between the cooler gulf airmass and the warmer Interior/Yukon airmass, these waves amplify and provide the forcing for diurnally enhanced showers and thunderstorms. Ridging over the northern portion of the state is breeding warm low level temperatures that will be advected down into the Southwest Mainland, as well as some juicy dewpoints by Alaska standards. These conditions are ripe for frequent lightning over mainly the Kuskokwim Valley and into Bristol Bay today. The upper level energy lingers through the weekend keeping at least showers in the forecast. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... A weakening system aloft over the Western Bering will bring rain today from Shemya through the Central Aleutians, and as far east as the Eastern Aleutians. That system will weaken through the weekend and not produce meaningful precipitation after today. A fairly narrow corridor of dense fog will set up today roughly from Saint Matthew through the Pribilofs and linger through tonight. && .LONG TERM FORECAST (Days 3 through 7)... On Sunday, the upper level pattern looks to grind to a halt from the easterly flow of weak disturbances to a much more chaotic movement. This will be due to the departure of the upper level low towards the Panhandle by Sunday morning, with no larger scale features following it. Thus, with everything being weak, any precipitation that develops Sunday over southern mainland Alaska will be scattered and weak. The persistence of a mid-level unstable layer over much of the area will result in some convection popping up with any showers that develop with enhanced lift, likely from topographic enhancement. For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...DS SOUTHCENTRAL ALASKA...SEB SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML LONG TERM...JW
Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 418 AM AKDT FRI JUL 1 2016 .DISCUSSION... UPPER AIR... A high pressure ridge currently extends from the Chukotsk Peninsula eastward across the Brooks Range into northwestern Canada, with a high center near the Bering Strait. The ridge will gradually transition to a high pressure center which will be pushed gradually eastward through Sunday night as a strong short wave drops southward out of the Russian Arctic Ocean. By late Sunday night the upper level high will be centered near Fort Yukon, with the strong short wave trough extending along 178W across the Chukchi Sea and Bering Sea. A series of weak short wave troughs will move westward across the southern interior through Saturday. A weak short wave trough is now moving westward across the central interior. The next short wave trough is now over the southern Yukon Territory and will move to the Alcan border by Friday morning then fracture into two troughs. The southern piece of the trough will continue to move westward and gradually deepen over the lower Kuskokwim Valley and southeastward Friday evening. The northern piece of the trough will stall out over the eastern interior Friday night and gradually weaken Saturday. SURFACE... A 1007 mb low centered near Northway will deepen to a 1001 mb low about 100 miles east of Northway by this afternoon, then remain nearly stationary through Saturday. A weak thermal trough will develop across the northern interior Saturday. INTERIOR... Areas or bands of showers and thunderstorms associated with the short wave troughs aloft will move westward across the southern interior and the Alaska Range, otherwise there will be isolated to scattered showers and isolated thunderstorms over most areas through the weekend. The heaviest rainfall today will likely be over Denali and the lower Kuskokwim Valley. The heaviest rainfall amounts tonight are expect to be in the lower Kuskokwim valley and in nearby area of the middle Yukon Valley. More showers and isolated thunderstorms are expected over much of the interior Saturday, and over much of the southern and eastern interior Sunday. ARCTIC SLOPE AND BROOKS RANGE... Areas of fog near the coast during the late night and early morning hours, otherwise no significant weather expected through Sunday. Warm temperatures in the interior with highs as high as the low to mid 70s. WEST COAST... No significant weather expected through Sunday. Some coastal areas may see areas of fog. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Some warming is expected in the interior over the weekend...with highs approaching or reaching 80 in some northern interior areas. Minimum humidities could approach 30 percent in the northern interior. Minimum humidities in the southern interior likely to remain at 35 percent or above. && .HYDROLOGY... Additional rainfall amounts of 0.5 to 1 inch are expected in Denali and the lower Kuskokwim Valley today. Northern parts of the Upper Tanana Valley and Fortymile country may see up to 0.5 inch, with local amounts of 0.75 inch possible. Locally heavier amounts will be possible in Denali and the lower Kuskokwim Valley today, but the location of the amounts remains uncertain due to the convective nature of the precipitation. && .AFG WATCHES/WARNINGS/ADVISORIES... Small craft advisory for PKZ245. && $$ RF JUN 16
Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 418 AM AKDT FRI JUL 1 2016 .DISCUSSION... UPPER AIR... A high pressure ridge currently extends from the Chukotsk Peninsula eastward across the Brooks Range into northwestern Canada, with a high center near the Bering Strait. The ridge will gradually transition to a high pressure center which will be pushed gradually eastward through Sunday night as a strong short wave drops southward out of the Russian Arctic Ocean. By late Sunday night the upper level high will be centered near Fort Yukon, with the strong short wave trough extending along 178W across the Chukchi Sea and Bering Sea. A series of weak short wave troughs will move westward across the southern interior through Saturday. A weak short wave trough is now moving westward across the central interior. The next short wave trough is now over the southern Yukon Territory and will move to the Alcan border by Friday morning then fracture into two troughs. The southern piece of the trough will continue to move westward and gradually deepen over the lower Kuskokwim Valley and southeastward Friday evening. The northern piece of the trough will stall out over the eastern interior Friday night and gradually weaken Saturday. SURFACE... A 1007 mb low centered near Northway will deepen to a 1001 mb low about 100 miles east of Northway by this afternoon, then remain nearly stationary through Saturday. A weak thermal trough will develop across the northern interior Saturday. INTERIOR... Areas or bands of showers and thunderstorms associated with the short wave troughs aloft will move westward across the southern interior and the Alaska Range, otherwise there will be isolated to scattered showers and isolated thunderstorms over most areas through the weekend. The heaviest rainfall today will likely be over Denali and the lower Kuskokwim Valley. The heaviest rainfall amounts tonight are expect to be in the lower Kuskokwim valley and in nearby area of the middle Yukon Valley. More showers and isolated thunderstorms are expected over much of the interior Saturday, and over much of the southern and eastern interior Sunday. ARCTIC SLOPE AND BROOKS RANGE... Areas of fog near the coast during the late night and early morning hours, otherwise no significant weather expected through Sunday. Warm temperatures in the interior with highs as high as the low to mid 70s. WEST COAST... No significant weather expected through Sunday. Some coastal areas may see areas of fog. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Some warming is expected in the interior over the weekend...with highs approaching or reaching 80 in some northern interior areas. Minimum humidities could approach 30 percent in the northern interior. Minimum humidities in the southern interior likely to remain at 35 percent or above. && .HYDROLOGY... Additional rainfall amounts of 0.5 to 1 inch are expected in Denali and the lower Kuskokwim Valley today. Northern parts of the Upper Tanana Valley and Fortymile country may see up to 0.5 inch, with local amounts of 0.75 inch possible. Locally heavier amounts will be possible in Denali and the lower Kuskokwim Valley today, but the location of the amounts remains uncertain due to the convective nature of the precipitation. && .AFG WATCHES/WARNINGS/ADVISORIES... Small craft advisory for PKZ245. && $$ RF JUN 16
Southcentral and Southwest Alaska Forecast Discussion...CORRECTED National Weather Service Anchorage AK 1108 PM AKDT THU JUN 30 2016 Corrected extended discussion .ANALYSIS AND UPPER LEVELS... The upper levels are starting to look like a mixed bag of goodies. The ever present upper level low spinning south of the gulf is slowly weakening but is continuing to eject shortwaves around it. The first of these waves moved across Southcentral last evening. The next is to the Northwest of PAYA and is noted on upper level analysis as an enhanced bubble of moisture and as a wiggle in the upper level analysis. This wave will move across the ALCAN border and across the Copper River Basin this afternoon. As of 2130z(1:30pm AKDT), showers are already beginning to form. This easterly wave will wrap around the low and slide across the Anchorage and Kenai areas tonight. A much more potent wave is easily identified in water vapor imagery near 49N 141W. As is the case with nearly stationary lows and these easterly waves that get ejected around, timing and placement has been a challenge. This strong wave is now progged to shift east and impact SE AK and BC. Farther west, a ridge between the Gulf low and a weakening Bering low is becoming pinched off as it retreats into the interior of Alaska. A strong upper level jet remains well south of the forecast area. At the surface, progress is being made on moving the nearly stationary low out of the gulf. A stalled out front stretches from a low in the Bering and southeast across the Akpen. && .MODEL DISCUSSION... All models are in pretty good agreement in the short term today. As briefly touched on in the analysis...the upper level low in the Gulf will shift east into the weaken. All of the models have varying levels of agreement with the shortwave strength and timing moving around the lows. The biggest trend from yesterday was slowing down the timing of the onset of the biggest rainmaker over Anchorage. The latest 18z runs of the NAM and GFS are showing a 9-12z time frame while the HRRR is hinting at an early start, between 5 and 6z. Judging by past performance of the HRRR and how poorly the major models play temporally, confidence in timing is low. However, all models are consistent with bringing in a healthy amount of rain across the region. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... Increasing mass ascent ahead of a low amplitude short wave trough over the Western Yukon and Eastern Copper Basin is beginning to manifest itself as increasing convective showers across the region. As the shortwave propagates west tonight, showers will begin to congeal into a large area of stratiform rain which will impact all of Southcentral tonight with brief periods of heavy rainfall. The heaviest axis of rain will likely occur across the Copper Basin into the Mat-Su Valleys, although areas along the Kenai and into Anchorage will also see the potential for brief heavy rains overnight. Thunderstorms have formed already along the Kenai Range, and they will also be possible along the Talkeetnas and Alaska Range as well as along the Chugach in the evening. The shortwave trough will elongate and quickly move west Friday, with most rain moving into Southwest Alaska by the afternoon. Showers will develop in the afternoon behind the main low, but these will be mainly along mountains and rather limited given lack of instability. Saturday will be warmer as broad cyclonic flow sets up over the region, with more afternoon showers but slightly warming temperatures. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... The upper level low over the Gulf continues to bring easterly flow with embedded shortwaves over Southwest Alaska. This combined with the unstable environment is helping to kick off thunderstorms over the area through Friday. The most likely times for thunderstorms are during peak heating and as the shortwaves move through. The shortwaves look to move through this evening, Friday morning and Friday evening. Friday will also see heavier rain from the Kuskokwim Valley south towards Bristol Bay and east towards the Alaska and Aleutian Ranges. Saturday will see a lesser chance for thunderstorms with the most likely area over the Kuskokwim Vally but rain will still be likely from the valley through Bristol Bay. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... A broad low over the Western Aleutians will last through the weekend slowly tracking east and bringing rain to the area. Areas from the Alaska Peninsula through the Pribilof Islands will be under the effects of weak ridging providing more fair conditions than areas to the west. && .LONG TERM FORECAST (Days 3 through 7)... On Sunday, the upper level pattern looks to grind to a halt from the easterly flow of weak disturbances to a much more chaotic movement. This will be due to the departure of the upper level low towards the Panhandle by Sunday morning, with no larger scale features following it. Thus, with everything being weak, any precipitation that develops Sunday over southern mainland Alaska will be scattered and weak. The persistence of a mid-level unstable layer over much of the area will result in some convection popping up with any showers that develop with enhanced lift, likely from topographic enhancement. For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...SS SOUTHCENTRAL ALASKA...JA SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK LONG TERM...JW
AREA FORECAST DISCUSSION
NWS LOS ANGELES/OXNARD CA
1100 AM PDT THU JUN 30 2016 ...Aviation discussion updated... .SYNOPSIS... Breezy winds for Santa Barbara...Ventura and Los Angeles mountains and deserts into Friday. The increasing onshore flow into Independence Day will spread the overnight marine layer farther inland and bring a cooling trend. The high should roll back in on Monday for a gradual warmup for next week. The temperatures will remain above normal through the forecast period. && .SHORT TERM...(TDY-SAT) .UPDATE...12z models so far offering up nothing really new to at least the short term portion of the forecast. Cooling trend with a deepening marine lyr the main themes the next few days. There`s a little bit of mid level moisture to our east today but aside from possibly a few afternoon cu over the mtns they shouldn`t amount to anything. Dry southwest flow will keep the area basically cloud free through the weekend with the exception of the night/morning marine lyr, some of which will hang around the beaches through the afternoon. && Overall, 00Z models in good synoptic agreement through the period. At upper levels, ridge will be replaced by a weak trough developing over northern/central California. Near the surface, onshore flow is forecast to gradually strengthen through the period. Forecast-wise, main concern in the short term will be the marine layer stratus as well as temperatures. Current sounding data indicates marine inversion running between 1000 and 1500 feet while satellite shows stratus filling in across the coastal plain. With the weak upper trough and increasing onshore flow, the marine inversion should deepen over the next couple of days with stratus and fog penetrating further inland to the coastal valleys. Each afternoon, the stratus should dissipate nicely as the inversion will likely not be too strong. Other than the marine layer stratus, skies should remain mostly clear through the period. As for temperatures, the increased marine influence as well as lowering thicknesses will lead to a cooling trend through Saturday. The most noticeable cooling will occur today and again on Friday with only minor additional cooling on Saturday. Temperatures on Friday/Saturday will generally be a couple degrees below seasonal normals. As for winds, the increasing onshore flow will likely generate some gusty afternoon/evening southwesterly winds across the mountains and deserts. However, at this time, there does not appear to be any wind that would approach advisory thresholds. .LONG TERM...(SUN-WED) Overall, 00Z models remain on the same synoptic page through the period. At upper levels, trough will disappear as a flat ridge builds in from the east. Near the surface, moderate onshore flow will continue (although slowly weakening from day-to-day). Forecast-wise, nothing too exciting is anticipated into the middle of next week. With the above synoptic pattern, the main issues will continue to be the marine layer stratus and temperatures. There will be some day-to-day variation in the areal coverage of the stratus, but still should be plenty of night/morning stratus in the coastal valleys each day. As for temperatures, there should be a gradual warming trend, especially away from the beaches. At this time, the mid-level flow looks to remain southwesterly which should keep any monsoonal moisture to the east through Wednesday. && .AVIATION...30/18Z... At 17Z at KLAX... The inversion was about 3950 feet deep. The top of the inversion was near 5600 feet with a temperature of about 25 degrees Celsius. Overall... Moderate confidence in the 18z TAFs. The uncertainty is primarily due to the timing of the marine incursion with some uncertainty regarding the location and intensity as well. The marine incursion is lingering a bit in some coastal locations but should be dissipated by late morning. It will return tonight in a similar fashion as to last night though a bit deeper and that will get it into the adjacent coastal valleys sooner and with greater intensity. The deeper incursion will result in a slightly delayed diminishment tomorrow morning but all sites are expected to be VFR by midday. Otherwise and elsewhere VFR conditions will prevail. KLAX... Moderate confidence in the 18z TAF. The uncertainty is primarily due to the timing of the marine incursion with some uncertainty regarding the intensity as well. VFR conditions will prevail into the evening then the marine incursion will return tonight in a similar fashion as to last night though a bit deeper. The deeper incursion will result in a slightly delayed diminishment tomorrow morning but KLAX should be VFR by late morning. KBUR... Moderate confidence in the 18z TAF. The uncertainty is primarily due to the timing of the marine incursion making its way into the San Fernando Valley tonight. The incursion will be deeper tonight so it will return sooner and with more intensity than last night. The deeper incursion will also result in a slightly delayed diminishment tomorrow morning but KBUR will be VFR by late morning. && .MARINE...30/830 AM... Overall... Small Craft Advisory winds will continue across the outer waters through the early morning hours. Steep combined seas of 7 to 10 feet across the outer waters will slowly subside tonight. Winds and seas across all coastal waters will remain below advisory levels from mid morning Friday through the weekend. Patchy dense fog will continue across the coastal waters into at least the weekend. && .LOX WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement in effect through Friday evening For zones 40-41-87. (See LAXCFWLOX). PZ...Small Craft Advisory in effect until 3 AM PDT Friday For zones 670-673-676. (See LAXMWWLOX). && $$ PUBLIC...MW/DB AVIATION...KJ MARINE...KJ SYNOPSIS...Seto weather.gov/losangeles
Area Forecast Discussion National Weather Service San Francisco Bay Area 1039 AM PDT THU JUN 30 2016 .SYNOPSIS...Onshore flow will continue to bring cooler air into far inland valleys through the weekend and into early next week. Temperatures will be near seasonal normals for the Fourth of July Holiday Weekend with seasonal temperatures likely persisting through the middle of next week. && .DISCUSSION...as of 09:10 AM PDT Thursday...The marine layer has deepened slightly overnight and resulted in stratus spreading well inland this morning, especially into the Salinas Valley. Meanwhile, drier air in the boundary layer continues to advect southward and has allowed cloud cover to burn-off rapidly this morning across the North Bay and over the northern offshore waters. Do expect the cloud cover to burn-off inland through the morning and give way to mostly sunny conditions. Daytime temperatures near the coast will greatly depend on if/when cloud cover clears along the coast. Upper 50s to lower 60s will be common near the coast with widespread 70s and 80s inland. However, do expect some 90s in the hills and far interior valleys again this afternoon. Have made a few adjustments to the sky cover to reflect current trends. Otherwise, the ongoing forecast remains on track for today with no major updates needed. && .PREV DISCUSSION...As of 2:52 AM PDT Thursday...The Fort Ord Profiler indicates a marine layer depth of around 1500 feet, and the latest satellite fog product imagery shows coastal stratus from the Golden Gate south, and also extending locally into the San Francisco Bay area and well into the Monterey Bay area and into the entire Salinas Valley. Temperatures are running steady compared to yesterday morning at this time with readings in the mid to upper 50s at most area airports. The onshore surface pressure gradients are still moderate to strong with 2.9 mb between SFO and SAC and 5.7 from SFO to LAS. High pressure aloft is weakening as an upper level trough settles in over the western states. This factor combined with the continued onshore flow will allow cooler air to filter inland. This will result in cooler temperatures through the weekend, and also persisting into next week as the trough deepens somewhat. High temperatures early next week are forecast to be at or below seasonal normals...upper 50s and 60s at the coast, to the 70s and 80s around the Bay, to the mid 90s well inland. Aside from occasional night and morning coastal fog/drizzle, conditions will be dry through the period. && .AVIATION...as of 10:33 AM PDT Thursday...With the exception of Monterey Bay terminals, VFR conditions prevail. Expect a very slow clearing for KMRY through this afternoon. Clouds linger along the coast through the day so an early return seems likely. IFR to MVFR Cigs tonight. Vicinity of KSFO...VRF through this evening. Cigs return after 06z and remain through the Friday AM rush. Gusty W to NW will be possible this afternoon. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...IFR cigs linger for KMRY with clearing on the doorstep of KSNS. Cigs return early this evening. && .MARINE...as of 10:32 AM PDT Thursday...High pressure over the eastern pacific will keep gusty north winds over the coastal waters. Winds will be strongest over the outer waters resulting in hazardous conditions. High pressure will weaken thursday evening bringing lighter winds to the inner coastal waters and improving sea conditions for the weekend. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tday...SCA...Pt Arena to Pigeon Pt 10-60 nm SCA...Pt Arena to Pt Reyes 0-10 nm SCA...SF Bay from 12 PM SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm && $$ PUBLIC FORECAST: RGass AVIATION: MM MARINE: MM Visit us at www.weather.gov/sanfrancisco Follow us on Facebook and twitter at: www.Facebook.com/nwsbayarea www.twitter.com/nwsbayarea
Area Forecast Discussion National Weather Service Phoenix AZ 943 AM MST THU JUN 30 2016 .SYNOPSIS... Plentiful monsoonal moisture will bring continued chances for showers and thunderstorms through at least Friday. Due to the increased moisture and cloud cover, high temperatures will fall with some locations dropping below 100 degrees today and Friday. There will be a return to drier southwest flow aloft over the weekend and into early next week which will limit thunderstorms to higher terrain areas east of Phoenix by Sunday. High temperatures will steadily climb late this week and early next week as the atmosphere becomes drier. && .DISCUSSION... A variety of cyclonic circulations evident in satellite imagery this morning. Some of these include one centered near Lake Mead, another over southern AZ, and another over southern Baja. These are in between troughing to our west and ridging centered over northwest Mexico and the interior western states. Radar imagery also indicates a circulation (likely an MCV from last night) centered near the Maricopa/Yavapai border. Otherwise, there is a lot of debris cloudiness covering most of AZ and Sonora. Near and west of the Lower Colorado River Valley. The vast majority of radar echoes this morning are weak showers associated with the aforementioned circulations. However, isolated stronger activity has developed over Mohave County where there has been less cloudiness. For our area, anticipating strongest convection to be over southwest AZ (mainly La Paz County) where surface heating will be better and there will be some steering flow advecting storms southwestward from Yavapai/Mohave Counties. Further west, there is good moisture and RAP depicts very high CAPE with decreasing CIN later this afternoon. May need to increase PoPs in these areas. Meanwhile over south-central AZ, thinking shower activity will be isolated to scattered the whole day but with only isolated stronger storms (more likely over higher terrain). However, with such high PWAT values, the showers will be very efficient rain producers. && .PREVIOUS DISCUSSION...Issued 329 am MST/PDT... A complex situation is ongoing across eastern Arizona and northern Mexico with multiple mesoscale features and broad upper level support. A very weak (but still relevant) upper level jet max is situated across the Baja northward into central Arizona. To the right of this jet is an area of difluence over southern Arizona which continues to aid in shower and thunderstorm develop early this morning. At least three distinct MCVs can be seen within radar imagery between Phoenix and Tucson. An inverted trough or even a weak closed mid level circulation also resides over northern Sonora Mexico. In the near term there remains enough mid level instability, low level foci, and upper level difluence to support persistent shower and thunderstorm development. Hi-res model data overall have been all over the place with what to expect the rest of tonight, but it seems likely enough the current activity will persist for several more hours. Given all this current activity, widespread cloud cover will likely persist through much of the day. Due to the cloud cover, it is difficult to determine whether this afternoon and evening will be extremely active. We start to lose some upper level support as flow aloft becomes less difluent, but the inverted trough over northern Sonora is shown to move into far southeastern Arizona by this evening. Moisture levels will continue to increase through tonight as 1000-700mb mixing ratios increase toward 12 g/kg as the inverted trough inches northward. Very moist mid levels should result in mostly cloudy skies through at least the south-central Arizona deserts and possibly as far west of the Lower Colorado River Valley. This should keep instability levels fairly low. Another inhibiting factor for any stronger thunderstorm activity will be the warming aloft that is forecast and rather weak mid level lapse rates. Taking all these factors into account, this afternoon and evening will still likely see scattered to even numerous showers east of the Colorado River, but overall thunderstorm activity may be dampened due to the lower instability. Tonight into early Friday may continue to be quite active at least across eastern Arizona as the mid level circulation tracks across Tucson by around midnight and then into east-central Arizona by 12Z Friday morning. The weak upper level jet max will also move into central Arizona by 12Z Friday providing additional support. The combination of the mid level circulation and the jet max will likely provide enough for showers and thunderstorms to last through tonight mainly east of Phoenix. During the day Friday, a drying upper level westerly flow overtakes most of Arizona likely scouring out any mid and upper level cloudiness by late morning. Ample low level and sufficient mid level moisture will still be present for Friday afternoon for us to likely see another day of scattered showers and thunderstorms, mainly from Phoenix eastward. There is some doubt to how much activity will be across the lower deserts as a southwesterly steering flow of 10-20kts will keep most high terrain storms off the lower deserts. The drying westerly flow will persist through this weekend into early next week with most lingering lower desert moisture mixing out on Saturday and completely being scoured out on Sunday. We should still see some isolated to scattered high terrain storms on Saturday, but activity will stay confined to areas east of Phoenix. By Monday, 1000-700mb mixing ratios drop to below 8 g/kg which is even likely too low for any high terrain storms. This flow looks to persist through Tuesday and possibly into next Wednesday before the high shifts far enough north into New Mexico to bring a moist southeasterly flow back to our region. Forecast temperatures during the period start out below normal for areas over Arizona through Friday due to the increased moisture and extensive cloud cover. Once the drying takes place this weekend, temperatures will be on the rebound with near normal highs by Sunday. Monday through Wednesday should see temperatures climb to above normal levels, but at this point it does not look like excessive heat will be a big concern. && .AVIATION... South-Central Arizona including KPHX, KIWA, and KSDL: Today feels more like a day that should be in August...not late June. Deep monsoon moisture surface with various embedded disturbances will continue to circulate through south-central AZ, supporting periods of BKN-OVC CIGS generally 8-10kft. Given the significant increase in moisture and some rainfall over the Phoenix area overnight, some lower SCT decks around nearby terrain/foothills cannot be ruled out. The stronger thunderstorm activity ended overnight, with showers and an isolated lightning strike or two possible through midday. Winds should maintain headings with some slight variants off of east through midday. Confidence in the forecast beyond midday degrades significantly. Conceptually, storm activity should be rather diminished today as the atmosphere is well mixed and worked over from last evenings storm activity. Usually a busy aftn/evening/overnight is followed by a less busy aftn/evening the next day. However, any sky clearing and solar heating of the moisture-rich atmosphere could allow for shower/thunder development into the evening again. For now, left the aftn/even rush periods with at least VCSH mention to introduce some mention of weather in the terminal airspace and elevated easterly breezes, potentially from outflow winds from nearby/on-going storms. Southeast California/Southwest Arizona including KIPL and KBLH: South to southeasterly headings to persist for the next 24 hours, with some afternoon gustiness possible for KBLH. SCT to BKN clouds will develop on and off through the day, with thicker clouds possible towards the afternoon and evening hours. Bulk of the thunderstorm activity should stay east of the river and across Arizona again today, but thunderstorm outflow winds and a few pulse thundershowers near KBLH are possible later this afternoon and evening. Aviation discussion not updated for amended TAFs. && .FIRE WEATHER... Saturday through Wednesday... Enhanced humidities and storm chances will continue on Saturday before trending downward, with minimum humidities in the lower deserts ranging from 20-30 percent on Saturday to 10-20 percent on Wednesday. Similarly, overnight recoveries will also be trending downward as we start to dry out this weekend. Thunderstorm chances on Saturday will be greatest north, east, and southeast of Phoenix. Sunday through Wednesday, thunderstorm chances will greatly decrease and be confined to the higher terrain of south-central AZ. Apart from strong erratic winds associated with thunderstorms, winds will primarily have a southerly component in southeast California and southwest Arizona through the period with some afternoon gustiness up to 20 mph. Over south-central Arizona, winds will following typical upslope and downslope directions with winds around 5 to 15 mph. && .SPOTTER INFORMATION STATEMENT... Spotter activation is not expected. && .PSR WATCHES/WARNINGS/ADVISORIES... AZ...None. CA...None. && $$ Visit us on Facebook...Twitter...and at weather.gov/phoenix DISCUSSION...AJ PREVIOUS DISCUSSION...Kuhlman AVIATION...Nolte FIRE WEATHER...Hernandez
AREA FORECAST DISCUSSION
National Weather Service Northern Indiana
801 PM EDT FRI JUL 1 2016 .SYNOPSIS... Issued at 116 PM EDT Fri Jul 1 2016 High pressure will build into the area overnight and Saturday. Gusty northwest winds and any remaining cloud cover will gradually diminish by this evening. Afternoon highs will be in the upper 60s and 70s. Under clear skies, low temperatures tonight will drop into the 50s. There is a high swim risk for Lake Michigan beaches through tonight. Conditions will be life threatening to anyone who enters the water. && .SHORT TERM...(This Evening through Monday) Issued at 217 PM EDT Fri Jul 1 2016 Water vapor imagery showing short wave pushing eastward into the eastern great lakes while surface analysis has cold front moving through the Ohio valley. Visible satellite indicating diminishing trends in stratocu cloud cover and expect this to continue as high pressure builds into the region. This will provide for a very pleasant start to the holiday weekend. Cool dry airmass will have temps dropping to near 50 tonight and comfortably in the 70s Saturday with low humidities. Stalled frontal boundary across the TN valley extending back into the southern plains will begin to lift northward as frontal wave develops in response to short wave energy ejecting eastward from the intermountain west. Still alot of spread and uncertainty with models in handling the evolution of this system for timing...placement...and strength. By 12Z Sunday...solutions have frontal wave ranging anywhere from Western MO and central KS down to OK and northern TX with some having northern edge of precip entering our far SW CWA by this time. Plan is to stay the course with going forecast and introduce pops beginning 12Z Sun in SW CWA and keep in chance range with focus of higher pops in the south...deviating from the blend which extends pops too far north too quickly and has likely in the south. Potent Theta-E ridge extending up into central Indiana will be coincident with PW exceeding 2 inches which will set the stage for a convective complex producing a significant rain event...not anticipating it extending up into our area at this time but certainly needs monitoring if models show any northward trends. && .LONG TERM...(Monday night through Friday) Issued at 217 PM EDT Fri Jul 1 2016 Models in decent agreement with the exit of frontal wave...moving from the Ohio valley to the mid Atlantic Monday night through Tuesday. Will trend precip chances accordingly with dry in the NW Monday night and entire CWA Tuesday and Tue night. Remainder of the extended still up in the air as models continue to offer varying solutions. GFS...operational and good agreement in the ensemble members...still building upper ridge while ECMWF continues to hint at northern stream dipping down into the region. Result has blend going with low chance pops days 5-7 with warmer and more humid conditions as highs get up toward 90 and 65-70 dewpoints will have overnight lows near 70. && .AVIATION...(For the 00Z TAFS through 00Z Saturday Evening) Issued at 800 PM EDT Fri Jul 1 2016 Vfr conds xpcd through the pd as sfc ridging builds acrs the Grtlakes. && .IWX Watches/Warnings/Advisories... IN...Beach Hazards Statement through Saturday morning for INZ003. MI...Beach Hazards Statement through Saturday morning for MIZ077. OH...NONE. LM...Small Craft Advisory until 8 AM EDT Saturday for LMZ043-046. && $$ SYNOPSIS...MCD SHORT TERM...JAL LONG TERM...JAL AVIATION...T Visit us at www.weather.gov/iwx Follow us on Facebook...Twitter...and YouTube at: www.facebook.com/NWSNorthernIndiana www.twitter.com/nwsiwx www.youtube.com/NWSNorthernIndiana
Area Forecast Discussion National Weather Service Indianapolis IN 631 PM EDT FRI JUL 1 2016 .UPDATE... The AVIATION Section has been updated below. && .SYNOPSIS... Issued at 340 PM EDT FRI JUL 1 2016 Cool High pressure over the upper midwest will move to north central Indiana Saturday and then retreat on to the east Sunday. Low pressure over the western U.S. will move across the southern and central Plains Saturday... the middle Mississippi valley Sunday and to south central Indiana Monday. This system will bring showers and a few thunderstorms along with heavy rainfall over over the 2nd half of the weekend. It will get hotter by the middle and later parts of next week as an upper ridge of high pressure builds across Indiana. Models continue low chances of thunderstorms much of next week. && .NEAR TERM /Tonight and Saturday/... Issued at 340 PM EDT FRI JUL 1 2016 A cold front was over the Ohio valley and high pressure was over the upper midwest. Satellite showed partly cloudy skies with scattered cu across the area. Expect most of these clouds to clear out after sunset. Models indicate thin mid/high clouds may begin moving in to at least western sections late tonight. High pressure will move to north central Indiana by Saturday. For most areas Saturday will be a nice day...but with thickening mid/high clouds. Will go mostly cloudy most areas by Saturday afternoon. Some models bring a few light showers into our far southwest by late Saturday afternoon. Will continue low chances of a few showers southwest of a Sullivan to Bedford line Saturday afternoon. However any rain amounts would be no more than a few hundredths. Concerning temperatures...went close to a MOS blend with lows in the lower to middle 50s tonight and highs Saturday in the middle 70s with some upper 70s east. && .SHORT TERM /Saturday Night through Monday/... Issued at 340 PM EDT FRI JUL 1 2016 Forecast challenges focus for the rest of the weekend will be for a threat of heavy rainfall...especially Saturday on increasing threats for locally heavy rainfall by late weekend as the front returns north into the region and becomes quasi-stationary. High pressure will retreat on to the east Saturday night and low pressure over the southern and central plains and a warm front to our southwest will be moving our way. Most models spread rain into west central and southern sections late Saturday night and across the rest of our region Sunday. Most models this run have trended a little farther north with the track of the heaviest rain with it more across the I70 corridor. The GEMNH takes the heaviest rain across our far northern sections. On the other hand...CONSALL and HPC still take the heaviest rain amounts across our south and I would suspect that some of the models may be too far north. For now will keep the heaviest rain amounts across our south...but even northern sections will see significant rainfall. Expect 3 to 4 inches across our southern sections and one to two inches across our far north over the 2nd half of the holiday weekend. The heaviest rainfall will occur late Sunday to early Monday. Will mention heavy rainfall all but far north Sunday night. Models indicate showers and thunderstorms will diminish some on Monday and by Monday evening we should only see a chance of showers and storms. Many areas could see a record low high on Sunday with rain spreading in along with cool air and dewpoints starting in the 50s Sunday. This will result in evaporational cooling which will hold temperatures down. Anyways expect highs from the upper 60s to lower 70s north and central Sunday to middle 70s far southwest. Highs Monday will be a little warmer with highs from the upper 70s to lower 80s. Concerning lows went slightly above a MOS blend with lows from 55 to 60 SAturday night and lower 60s northeast to around 70 southwest Sunday night. && .LONG TERM /Monday Night Through Friday/... Issued at 241 PM EDT Fri Jul 1 2016 Models are close enough that the SuperBlend initialization was accepted for most items. Rain chances will continue for most areas throughout the Long Term. Monday night into Tuesday will see rain chances lingering from a exiting low pressure system. Afterward, the area will be on the edge of an upper level ridge, which will allow various waves to ride around the ridge into the area. Of course timing is very uncertain that far out. Heat and humidity will increase through the period as the upper ridge gets closer. Highs look to be in the 90s by Thursday and Friday with potential heat index values around 100. && .AVIATION /Discussion for 020000Z TAF issuance/... Issued at 625 PM EDT Fri Jul 1 2016 High pressure will be in control overnight giving VFR conditions through morning. Next weather system will begin effecting the region with mostly high cloudiness late Saturday morning, then increasing through the day. It looks like Saturday, for the most part, will be VFR, with the exception of maybe KHUF/KLAF where there may be some VCSH towards evening. Looks like conditions begin to deteriorate late Saturday, definitely Sunday as low pressure comes out of the Plains towards our area. && .IND Watches/Warnings/Advisories... NONE. && $$ SYNOPSIS...RYAN NEAR TERM...JH SHORT TERM...JH LONG TERM....JH AVIATION...DWM
Area Forecast Discussion National Weather Service Indianapolis IN 430 PM EDT FRI JUL 1 2016 .UPDATE... The aviation section has been updated below. && .SYNOPSIS... Issued at 340 PM EDT FRI JUL 1 2016 Cool High pressure over the upper midwest will move to north central Indiana Saturday and then retreat on to the east Sunday. Low pressure over the western U.S. will move across the southern and central Plains Saturday... the middle Mississippi valley Sunday and to south central Indiana Monday. This system will bring showers and a few thunderstorms along with heavy rainfall over over the 2nd half of the weekend. It will get hotter by the middle and later parts of next week as an upper ridge of high pressure builds across Indiana. Models continue low chances of thunderstorms much of next week. && .NEAR TERM /Tonight and Saturday/... Issued at 340 PM EDT FRI JUL 1 2016 A cold front was over the Ohio valley and high pressure was over the upper midwest. Satellite showed partly cloudy skies with scattered cu across the area. Expect most of these clouds to clear out after sunset. Models indicate thin mid/high clouds may begin moving in to at least western sections late tonight. High pressure will move to north central Indiana by Saturday. For most areas Saturday will be a nice day...but with thickening mid/high clouds. Will go mostly cloudy most areas by Saturday afternoon. Some models bring a few light showers into our far southwest by late Saturday afternoon. Will continue low chances of a few showers southwest of a Sullivan to Bedford line Saturday afternoon. However any rain amounts would be no more than a few hundredths. Concerning temperatures...went close to a MOS blend with lows in the lower to middle 50s tonight and highs Saturday in the middle 70s with some upper 70s east. && .SHORT TERM /Saturday Night through Monday/... Issued at 340 PM EDT FRI JUL 1 2016 Forecast challenges focus for the rest of the weekend will be for a threat of heavy rainfall...especially Saturday on increasing threats for locally heavy rainfall by late weekend as the front returns north into the region and becomes quasi-stationary. High pressure will retreat on to the east Saturday night and low pressure over the southern and central plains and a warm front to our southwest will be moving our way. Most models spread rain into west central and southern sections late Saturday night and across the rest of our region Sunday. Most models this run have trended a little farther north with the track of the heaviest rain with it more across the I70 corridor. The GEMNH takes the heaviest rain across our far northern sections. On the other hand...CONSALL and HPC still take the heaviest rain amounts across our south and I would suspect that some of the models may be too far north. For now will keep the heaviest rain amounts across our south...but even northern sections will see significant rainfall. Expect 3 to 4 inches across our southern sections and one to two inches across our far north over the 2nd half of the holiday weekend. The heaviest rainfall will occur late Sunday to early Monday. Will mention heavy rainfall all but far north Sunday night. Models indicate showers and thunderstorms will diminish some on Monday and by Monday evening we should only see a chance of showers and storms. Many areas could see a record low high on Sunday with rain spreading in along with cool air and dewpoints starting in the 50s Sunday. This will result in evaporational cooling which will hold temperatures down. Anyways expect highs from the upper 60s to lower 70s north and central Sunday to middle 70s far southwest. Highs Monday will be a little warmer with highs from the upper 70s to lower 80s. Concerning lows went slightly above a MOS blend with lows from 55 to 60 SAturday night and lower 60s northeast to around 70 southwest Sunday night. && .LONG TERM /Monday Night Through Friday/... Issued at 241 PM EDT Fri Jul 1 2016 Models are close enough that the SuperBlend initialization was accepted for most items. Rain chances will continue for most areas throughout the Long Term. Monday night into Tuesday will see rain chances lingering from a exiting low pressure system. Afterward, the area will be on the edge of an upper level ridge, which will allow various waves to ride around the ridge into the area. Of course timing is very uncertain that far out. Heat and humidity will increase through the period as the upper ridge gets closer. Highs look to be in the 90s by Thursday and Friday with potential heat index values around 100. && .AVIATION /Updated Discussion for the 011800Z TAF Issuance/... Issued at 430 PM EDT Fri Jul 1 2016 Cold front has moved south of the Ohio River at this hour as high pressure has moved in with only scatter cumulus clouds. Skies expected to clear for tonight into Saturday, thus VFR conditions through much of tomorrow. Previous discussion below... VFR conditions expected through the period. Broken cumulus field will have lifted to VFR levels by valid time, and this field will break up during the afternoon as subsidence develops over the area. Otherwise a gradual increase in high and eventually mid cloud can be expected. North winds around 10kt (perhaps some gusts to 15kt) this afternoon will diminish around sunset, then become light east by Saturday morning. && .IND Watches/Warnings/Advisories... NONE. && $$ SYNOPSIS...RYAN NEAR TERM...JH SHORT TERM...JH LONG TERM....JH AVIATION...50/DWM
Area Forecast Discussion National Weather Service Indianapolis IN 430 PM EDT FRI JUL 1 2016 .UPDATE... The aviation section has been updated below. && .SYNOPSIS... Issued at 340 PM EDT FRI JUL 1 2016 Cool High pressure over the upper midwest will move to north central Indiana Saturday and then retreat on to the east Sunday. Low pressure over the western U.S. will move across the southern and central Plains Saturday... the middle Mississippi valley Sunday and to south central Indiana Monday. This system will bring showers and a few thunderstorms along with heavy rainfall over over the 2nd half of the weekend. It will get hotter by the middle and later parts of next week as an upper ridge of high pressure builds across Indiana. Models continue low chances of thunderstorms much of next week. && .NEAR TERM /Tonight and Saturday/... Issued at 340 PM EDT FRI JUL 1 2016 A cold front was over the Ohio valley and high pressure was over the upper midwest. Satellite showed partly cloudy skies with scattered cu across the area. Expect most of these clouds to clear out after sunset. Models indicate thin mid/high clouds may begin moving in to at least western sections late tonight. High pressure will move to north central Indiana by Saturday. For most areas Saturday will be a nice day...but with thickening mid/high clouds. Will go mostly cloudy most areas by Saturday afternoon. Some models bring a few light showers into our far southwest by late Saturday afternoon. Will continue low chances of a few showers southwest of a Sullivan to Bedford line Saturday afternoon. However any rain amounts would be no more than a few hundredths. Concerning temperatures...went close to a MOS blend with lows in the lower to middle 50s tonight and highs Saturday in the middle 70s with some upper 70s east. && .SHORT TERM /Saturday Night through Monday/... Issued at 340 PM EDT FRI JUL 1 2016 Forecast challenges focus for the rest of the weekend will be for a threat of heavy rainfall...especially Saturday on increasing threats for locally heavy rainfall by late weekend as the front returns north into the region and becomes quasi-stationary. High pressure will retreat on to the east Saturday night and low pressure over the southern and central plains and a warm front to our southwest will be moving our way. Most models spread rain into west central and southern sections late Saturday night and across the rest of our region Sunday. Most models this run have trended a little farther north with the track of the heaviest rain with it more across the I70 corridor. The GEMNH takes the heaviest rain across our far northern sections. On the other hand...CONSALL and HPC still take the heaviest rain amounts across our south and I would suspect that some of the models may be too far north. For now will keep the heaviest rain amounts across our south...but even northern sections will see significant rainfall. Expect 3 to 4 inches across our southern sections and one to two inches across our far north over the 2nd half of the holiday weekend. The heaviest rainfall will occur late Sunday to early Monday. Will mention heavy rainfall all but far north Sunday night. Models indicate showers and thunderstorms will diminish some on Monday and by Monday evening we should only see a chance of showers and storms. Many areas could see a record low high on Sunday with rain spreading in along with cool air and dewpoints starting in the 50s Sunday. This will result in evaporational cooling which will hold temperatures down. Anyways expect highs from the upper 60s to lower 70s north and central Sunday to middle 70s far southwest. Highs Monday will be a little warmer with highs from the upper 70s to lower 80s. Concerning lows went slightly above a MOS blend with lows from 55 to 60 SAturday night and lower 60s northeast to around 70 southwest Sunday night. && .LONG TERM /Monday Night Through Friday/... Issued at 241 PM EDT Fri Jul 1 2016 Models are close enough that the SuperBlend initialization was accepted for most items. Rain chances will continue for most areas throughout the Long Term. Monday night into Tuesday will see rain chances lingering from a exiting low pressure system. Afterward, the area will be on the edge of an upper level ridge, which will allow various waves to ride around the ridge into the area. Of course timing is very uncertain that far out. Heat and humidity will increase through the period as the upper ridge gets closer. Highs look to be in the 90s by Thursday and Friday with potential heat index values around 100. && .AVIATION /Updated Discussion for the 011800Z TAF Issuance/... Issued at 430 PM EDT Fri Jul 1 2016 Cold front has moved south of the Ohio River at this hour as high pressure has moved in with only scatter cumulus clouds. Skies expected to clear for tonight into Saturday, thus VFR conditions through much of tomorrow. Previous discussion below... VFR conditions expected through the period. Broken cumulus field will have lifted to VFR levels by valid time, and this field will break up during the afternoon as subsidence develops over the area. Otherwise a gradual increase in high and eventually mid cloud can be expected. North winds around 10kt (perhaps some gusts to 15kt) this afternoon will diminish around sunset, then become light east by Saturday morning. && .IND Watches/Warnings/Advisories... NONE. && $$ SYNOPSIS...RYAN NEAR TERM...JH SHORT TERM...JH LONG TERM....JH AVIATION...50/DWM
Area Forecast Discussion National Weather Service Indianapolis IN 340 PM EDT FRI JUL 1 2016 .UPDATE... Synopsis...Near term and short term sections have been updated below. && .SYNOPSIS... Issued at 340 PM EDT FRI JUL 1 2016 Cool High pressure over the upper midwest will move to north central Indiana Saturday and then retreat on to the east Sunday. Low pressure over the western U.S. will move across the southern and central Plains Saturday... the middle Mississippi valley Sunday and to south central Indiana Monday. This system will bring showers and a few thunderstorms along with heavy rainfall over over the 2nd half of the weekend. It will get hotter by the middle and later parts of next week as an upper ridge of high pressure builds across Indiana. Models continue low chances of thunderstorms much of next week. && .NEAR TERM /Tonight and Saturday/... Issued at 340 PM EDT FRI JUL 1 2016 A cold front was over the Ohio valley and high pressure was over the upper midwest. Satellite showed partly cloudy skies with scattered cu across the area. Expect most of these clouds to clear out after sunset. Models indicate thin mid/high clouds may begin moving in to at least western sections late tonight. High pressure will move to north central Indiana by Saturday. For most areas Saturday will be a nice day...but with thickening mid/high clouds. Will go mostly cloudy most areas by Saturday afternoon. Some models bring a few light showers into our far southwest by late Saturday afternoon. Will continue low chances of a few showers southwest of a Sullivan to Bedford line Saturday afternoon. However any rain amounts would be no more than a few hundredths. Concerning temperatures...went close to a MOS blend with lows in the lower to middle 50s tonight and highs Saturday in the middle 70s with some upper 70s east. && .SHORT TERM /Saturday Night through Monday/... Issued at 340 PM EDT FRI JUL 1 2016 Forecast challenges focus for the rest of the weekend will be for a threat of heavy rainfall...especially Saturday on increasing threats for locally heavy rainfall by late weekend as the front returns north into the region and becomes quasi-stationary. High pressure will retreat on to the east Saturday night and low pressure over the southern and central plains and a warm front to our southwest will be moving our way. Most models spread rain into west central and southern sections late Saturday night and across the rest of our region Sunday. Most models this run have trended a little farther north with the track of the heaviest rain with it more across the I70 corridor. The GEMNH takes the heaviest rain across our far northern sections. On the other hand...CONSALL and HPC still take the heaviest rain amounts across our south and I would suspect that some of the models may be too far north. For now will keep the heaviest rain amounts across our south...but even northern sections will see significant rainfall. Expect 3 to 4 inches across our southern sections and one to two inches across our far north over the 2nd half of the holiday weekend. The heaviest rainfall will occur late Sunday to early Monday. Will mention heavy rainfall all but far north Sunday night. Models indicate showers and thunderstorms will diminish some on Monday and by Monday evening we should only see a chance of showers and storms. Many areas could see a record low high on Sunday with rain spreading in along with cool air and dewpoints starting in the 50s Sunday. This will result in evaporational cooling which will hold temperatures down. Anyways expect highs from the upper 60s to lower 70s north and central Sunday to middle 70s far southwest. Highs Monday will be a little warmer with highs from the upper 70s to lower 80s. Concerning lows went slightly above a MOS blend with lows from 55 to 60 SAturday night and lower 60s northeast to around 70 southwest Sunday night. && .LONG TERM /Monday Night Through Friday/... Issued at 241 PM EDT Fri Jul 1 2016 Models are close enough that the SuperBlend initialization was accepted for most items. Rain chances will continue for most areas throughout the Long Term. Monday night into Tuesday will see rain chances lingering from a exiting low pressure system. Afterward, the area will be on the edge of an upper level ridge, which will allow various waves to ride around the ridge into the area. Of course timing is very uncertain that far out. Heat and humidity will increase through the period as the upper ridge gets closer. Highs look to be in the 90s by Thursday and Friday with potential heat index values around 100. && .AVIATION /Discussion for the 011800Z TAF Issuance/... Issued at 1219 PM EDT Fri Jul 1 2016 VFR conditions expected through the period. Broken cumulus field will have lifted to VFR levels by valid time, and this field will break up during the afternoon as subsidence develops over the area. Otherwise a gradual increase in high and eventually mid cloud can be expected. North winds around 10kt (perhaps some gusts to 15kt) this afternoon will diminish around sunset, then become light east by Saturday morning. && .IND Watches/Warnings/Advisories... NONE. && $$ SYNOPSIS...RYAN NEAR TERM...JH SHORT TERM...JH LONG TERM....JH AVIATION...50
Area Forecast Discussion National Weather Service Indianapolis IN 241 PM EDT FRI JUL 1 2016 .UPDATE... The LONG TERM section has been updated below. && .SYNOPSIS... Issued at 355 AM EDT Fri Jul 1 2016 A cold front will move quickly through the area this morning and may bring a few showers and storms. High pressure will then return with dry pleasant weather into Saturday. A much more unsettled and active pattern sets up beginning Sunday through the early part of next week as the front returns back into the region and becomes nearly stationary. Warmer weather will arrive later next week along with the potential for more storms as central Indiana resides on the edge of an expanding upper ridge. && .NEAR TERM /Rest of Today/... Issued at 920 AM EDT Fri Jul 1 2016 Update...Showers and thunderstorms had just about ended across our forecast area. The only area remaining was far southern Daviess.. Martin...Lawrence and Jackson counties. Could see a POP up shower south for another hour or two. The main update...will be to drop the early morning part of forecast. Surface chart indicated cold front extended from near Richmond to just south of Sullivan at 1300Z. Tweaked temperatures and rest of near term slightly. But overall everything is on track. Portion of previous near term discussion follows... Any rain will be gone by midday as the upper wave and surface front quickly move off to the southeast and are replaced by a renewed surge of drier air and deep subsidence. Water vapor imagery showing a slug of very dry air currently present across the mid Mississippi Valley. Expect this to advect into the area by late morning with sunshine increasing as the day progresses. Mainly clear skies are expected by late afternoon as high pressure builds into the area. Temps...expect temps to warm nicely this afternoon in the drier airmass. Trended towards warmer METMOS which was supported by forecast low level thermals. Should see highs ranging from he mid 70s into the lower 80s most locales. && .SHORT TERM /Tonight through Sunday Night/... Issued at 355 AM EDT Fri Jul 1 2016 Forecast challenges focus on increasing threats for locally heavy rainfall by late weekend as the front returns north into the region and becomes quasi-stationary. Initially...high pressure will maintain dry pleasant weather through most of Saturday as it drifts slowly through the Ohio Valley. Model soundings and RH progs show the deeper layer of subsidence remaining over the region into Saturday...aided by low level flow veering from northerly to E/NE. Chances for rain will slowly increase from the southwest Saturday afternoon and night as moisture and isentropic lift arrive into the region. The drier airmass will be slow to saturate however with more widespread rain holding off for many until near or after daybreak Sunday. Upper energy currently over the Four Corners region will eject out into the central Plains on Saturday then shift east into the Ohio Valley by Sunday. Additional upper waves will follow as an easterly flow aloft aligns between a flat but strong ridge across the far southern part of the country and deeper upper lows along the western and eastern Canadian coasts. This will draw moisture with a Pacific origin east into the central Plains...mid Mississippi Valley and Ohio Valley. At the same time...southwest low level flow will develop around the back side of the Bermuda high and transport rich tropical Gulf moisture into these same regions for the second half of the weekend into early next week. The remnant frontal boundary will be drawn back north in response to the waves aloft kicking out to the east...and will serve as a focusing mechanism for repeated rounds of locally heavy rainfall beginning in the central Plains Saturday and shifting east into the Ohio Valley for Sunday and Monday. To the chagrin of many...confidence continues to grow in negative impacts for those with outdoor plans both Sunday and Monday as the frontal boundary will likely set up somewhere across the southern portions of Illinois and Indiana. The exact location of where the boundary ends up will be a big factor in where the heavy rain axis aligns. With that being said...numerous factors are strongly suggestive of a period of moderate to locally heavy rainfall focused from late Sunday afternoon into Sunday night and for some...likely persisting into Independence Day. The dual moisture surges coming from both the Pacific and Gulf will produce an impressive axis of high precip water values at 2 to 3 standard deviations above normal for July...in excess of 2 inches across much of central Indiana. Precip efficiency is maximized along and south of the I-70 corridor as deep convergence up to 700mb organizes at the nose of a 40-45kt low level jet Sunday afternoon and night. Strong frontogenetical forcing and diffluence aloft are also present along the boundary and should further enhance rainfall coverage and intensity Sunday night. Feel comfortable raising pops for the entire area and focusing the highest pops at this time along and south of the I-70 corridor for Sunday and Sunday night. There are still likely to be some fluctuations in the heaviest rainfall and where the frontal boundary aligns but as discussed above...numerous signals supporting the mention of heavy rainfall for the southern 2/3 of the forecast area late Sunday into Sunday night. The severe threat south of the front should largely remain just south of the forecast area...but again any northward bump to the boundary would bring that possibility into play for Sunday and Sunday night. Lots still to work out in the coming 24-48 hours ahead of the rain. Temps...felt a model blend generally handled highs and lows well through the period. With the rain/storms and clouds on Sunday... there exists a real possibility that highs have a difficult time even making it to 70 in some locations. The record for coolest high for July 3 is 70 at Indy from 1924 and that could be in jeopardy. && .LONG TERM /Monday Night Through Friday/... Issued at 241 PM EDT Fri Jul 1 2016 Models are close enough that the SuperBlend initialization was accepted for most items. Rain chances will continue for most areas throughout the Long Term. Monday night into Tuesday will see rain chances lingering from a exiting low pressure system. Afterward, the area will be on the edge of an upper level ridge, which will allow various waves to ride around the ridge into the area. Of course timing is very uncertain that far out. Heat and humidity will increase through the period as the upper ridge gets closer. Highs look to be in the 90s by Thursday and Friday with potential heat index values around 100. && .AVIATION /Discussion for the 011800Z TAF Issuance/... Issued at 1219 PM EDT Fri Jul 1 2016 VFR conditions expected through the period. Broken cumulus field will have lifted to VFR levels by valid time, and this field will break up during the afternoon as subsidence develops over the area. Otherwise a gradual increase in high and eventually mid cloud can be expected. North winds around 10kt (perhaps some gusts to 15kt) this afternoon will diminish around sunset, then become light east by Saturday morning. && .IND Watches/Warnings/Advisories... NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN/JH SHORT TERM...RYAN LONG TERM....50 AVIATION...50
Area Forecast Discussion National Weather Service Indianapolis IN 241 PM EDT FRI JUL 1 2016 .UPDATE... The LONG TERM section has been updated below. && .SYNOPSIS... Issued at 355 AM EDT Fri Jul 1 2016 A cold front will move quickly through the area this morning and may bring a few showers and storms. High pressure will then return with dry pleasant weather into Saturday. A much more unsettled and active pattern sets up beginning Sunday through the early part of next week as the front returns back into the region and becomes nearly stationary. Warmer weather will arrive later next week along with the potential for more storms as central Indiana resides on the edge of an expanding upper ridge. && .NEAR TERM /Rest of Today/... Issued at 920 AM EDT Fri Jul 1 2016 Update...Showers and thunderstorms had just about ended across our forecast area. The only area remaining was far southern Daviess.. Martin...Lawrence and Jackson counties. Could see a POP up shower south for another hour or two. The main update...will be to drop the early morning part of forecast. Surface chart indicated cold front extended from near Richmond to just south of Sullivan at 1300Z. Tweaked temperatures and rest of near term slightly. But overall everything is on track. Portion of previous near term discussion follows... Any rain will be gone by midday as the upper wave and surface front quickly move off to the southeast and are replaced by a renewed surge of drier air and deep subsidence. Water vapor imagery showing a slug of very dry air currently present across the mid Mississippi Valley. Expect this to advect into the area by late morning with sunshine increasing as the day progresses. Mainly clear skies are expected by late afternoon as high pressure builds into the area. Temps...expect temps to warm nicely this afternoon in the drier airmass. Trended towards warmer METMOS which was supported by forecast low level thermals. Should see highs ranging from he mid 70s into the lower 80s most locales. && .SHORT TERM /Tonight through Sunday Night/... Issued at 355 AM EDT Fri Jul 1 2016 Forecast challenges focus on increasing threats for locally heavy rainfall by late weekend as the front returns north into the region and becomes quasi-stationary. Initially...high pressure will maintain dry pleasant weather through most of Saturday as it drifts slowly through the Ohio Valley. Model soundings and RH progs show the deeper layer of subsidence remaining over the region into Saturday...aided by low level flow veering from northerly to E/NE. Chances for rain will slowly increase from the southwest Saturday afternoon and night as moisture and isentropic lift arrive into the region. The drier airmass will be slow to saturate however with more widespread rain holding off for many until near or after daybreak Sunday. Upper energy currently over the Four Corners region will eject out into the central Plains on Saturday then shift east into the Ohio Valley by Sunday. Additional upper waves will follow as an easterly flow aloft aligns between a flat but strong ridge across the far southern part of the country and deeper upper lows along the western and eastern Canadian coasts. This will draw moisture with a Pacific origin east into the central Plains...mid Mississippi Valley and Ohio Valley. At the same time...southwest low level flow will develop around the back side of the Bermuda high and transport rich tropical Gulf moisture into these same regions for the second half of the weekend into early next week. The remnant frontal boundary will be drawn back north in response to the waves aloft kicking out to the east...and will serve as a focusing mechanism for repeated rounds of locally heavy rainfall beginning in the central Plains Saturday and shifting east into the Ohio Valley for Sunday and Monday. To the chagrin of many...confidence continues to grow in negative impacts for those with outdoor plans both Sunday and Monday as the frontal boundary will likely set up somewhere across the southern portions of Illinois and Indiana. The exact location of where the boundary ends up will be a big factor in where the heavy rain axis aligns. With that being said...numerous factors are strongly suggestive of a period of moderate to locally heavy rainfall focused from late Sunday afternoon into Sunday night and for some...likely persisting into Independence Day. The dual moisture surges coming from both the Pacific and Gulf will produce an impressive axis of high precip water values at 2 to 3 standard deviations above normal for July...in excess of 2 inches across much of central Indiana. Precip efficiency is maximized along and south of the I-70 corridor as deep convergence up to 700mb organizes at the nose of a 40-45kt low level jet Sunday afternoon and night. Strong frontogenetical forcing and diffluence aloft are also present along the boundary and should further enhance rainfall coverage and intensity Sunday night. Feel comfortable raising pops for the entire area and focusing the highest pops at this time along and south of the I-70 corridor for Sunday and Sunday night. There are still likely to be some fluctuations in the heaviest rainfall and where the frontal boundary aligns but as discussed above...numerous signals supporting the mention of heavy rainfall for the southern 2/3 of the forecast area late Sunday into Sunday night. The severe threat south of the front should largely remain just south of the forecast area...but again any northward bump to the boundary would bring that possibility into play for Sunday and Sunday night. Lots still to work out in the coming 24-48 hours ahead of the rain. Temps...felt a model blend generally handled highs and lows well through the period. With the rain/storms and clouds on Sunday... there exists a real possibility that highs have a difficult time even making it to 70 in some locations. The record for coolest high for July 3 is 70 at Indy from 1924 and that could be in jeopardy. && .LONG TERM /Monday Night Through Friday/... Issued at 241 PM EDT Fri Jul 1 2016 Models are close enough that the SuperBlend initialization was accepted for most items. Rain chances will continue for most areas throughout the Long Term. Monday night into Tuesday will see rain chances lingering from a exiting low pressure system. Afterward, the area will be on the edge of an upper level ridge, which will allow various waves to ride around the ridge into the area. Of course timing is very uncertain that far out. Heat and humidity will increase through the period as the upper ridge gets closer. Highs look to be in the 90s by Thursday and Friday with potential heat index values around 100. && .AVIATION /Discussion for the 011800Z TAF Issuance/... Issued at 1219 PM EDT Fri Jul 1 2016 VFR conditions expected through the period. Broken cumulus field will have lifted to VFR levels by valid time, and this field will break up during the afternoon as subsidence develops over the area. Otherwise a gradual increase in high and eventually mid cloud can be expected. North winds around 10kt (perhaps some gusts to 15kt) this afternoon will diminish around sunset, then become light east by Saturday morning. && .IND Watches/Warnings/Advisories... NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN/JH SHORT TERM...RYAN LONG TERM....50 AVIATION...50
Area Forecast Discussion National Weather Service Northern Indiana 221 PM EDT FRI JUL 1 2016 .SYNOPSIS... Issued at 116 PM EDT Fri Jul 1 2016 High pressure will build into the area overnight and Saturday. Gusty northwest winds and any remaining cloud cover will gradually diminish by this evening. Afternoon highs will be in the upper 60s and 70s. Under clear skies, low temperatures tonight will drop into the 50s. There is a high swim risk for Lake Michigan beaches through tonight. Conditions will be life threatening to anyone who enters the water. && .SHORT TERM...(This Evening through Monday) Issued at 217 PM EDT Fri Jul 1 2016 Water vapor imagery showing short wave pushing eastward into the eastern great lakes while surface analysis has cold front moving through the Ohio valley. Visible satellite indicating diminishing trends in stratocu cloud cover and expect this to continue as high pressure builds into the region. This will provide for a very pleasant start to the holiday weekend. Cool dry airmass will have temps dropping to near 50 tonight and comfortably in the 70s Saturday with low humidities. Stalled frontal boundary across the TN valley extending back into the southern plains will begin to lift northward as frontal wave develops in response to short wave energy ejecting eastward from the intermountain west. Still alot of spread and uncertainty with models in handling the evolution of this system for timing...placement...and strength. By 12Z Sunday...solutions have frontal wave ranging anywhere from Western MO and central KS down to OK and northern TX with some having northern edge of precip entering our far SW CWA by this time. Plan is to stay the course with going forecast and introduce pops beginning 12Z Sun in SW CWA and keep in chance range with focus of higher pops in the south...deviating from the blend which extends pops too far north too quickly and has likely in the south. Potent Theta-E ridge extending up into central Indiana will be coincident with PW exceeding 2 inches which will set the stage for a convective complex producing a significant rain event...not anticipating it extending up into our area at this time but certainly needs monitoring if models show any northward trends. && .LONG TERM...(Monday night through Friday) Issued at 217 PM EDT Fri Jul 1 2016 Models in decent agreement with the exit of frontal wave...moving from the Ohio valley to the mid Atlantic Monday night through Tuesday. Will trend precip chances accordingly with dry in the NW Monday night and entire CWA Tuesday and Tue night. Remainder of the extended still up in the air as models continue to offer varying solutions. GFS...operational and good agreement in the ensemble members...still building upper ridge while ECMWF continues to hint at northern stream dipping down into the region. Result has blend going with low chance pops days 5-7 with warmer and more humid conditions as highs get up toward 90 and 65-70 dewpoints will have overnight lows near 70. && .AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon) Issued at 116 PM EDT Fri Jul 1 2016 As of 1730Z this afternoon a cold front was drifting southeast of the TAF sites with high pressure building in its wake. Large scale subsidence and gradual drying will continue to scour out remaining MVFR cloud decks by late afternoon. Northwest winds gusting as high as 25 knots will begin to diminish towards the evening hours as well. Expect VFR conditions tonight and Saturday. && .IWX Watches/Warnings/Advisories... IN...Beach Hazards Statement through Saturday morning for INZ003. MI...Beach Hazards Statement through Saturday morning for MIZ077. OH...NONE. LM...Small Craft Advisory until 8 AM EDT Saturday for LMZ043-046. && $$ SYNOPSIS...MCD SHORT TERM...JAL LONG TERM...JAL AVIATION...MCD Visit us at www.weather.gov/iwx Follow us on Facebook...Twitter...and YouTube at: www.facebook.com/NWSNorthernIndiana www.twitter.com/nwsiwx www.youtube.com/NWSNorthernIndiana
Area Forecast Discussion National Weather Service Northern Indiana 121 PM EDT FRI JUL 1 2016 .SYNOPSIS... Issued at 116 PM EDT Fri Jul 1 2016 High pressure will build into the area overnight and Saturday. Gusty northwest winds and any remaining cloud cover will gradually diminish by this evening. Afternoon highs will be in the upper 60s and 70s. Under clear skies, low temperatures tonight will drop into the 50s. There is a high swim risk for Lake Michigan beaches through tonight. Conditions will be life threatening to anyone who enters the water. && .SHORT TERM...(Today and Tonight) Issued at 351 AM EDT Fri Jul 1 2016 Short wave rotating through the Great Lakes early this morning was responsible for a broken line of showers and a few isolated thunderstorms ahead of associated sfc cold front. These showers and the cold front should move steadily east and exit the far eastern portions of NW Ohio counties around or shortly after 12z. Clearing looks to quickly follow with IR satellite showing clearing skies immediately behind front and water vapor showing substantial drying/subsidence. Skies expected to become mostly sunny with another cool and comfortable day in store for beginning of July. Highs will range from 60s near Lake Michigan to middle and upper 70s over the far south and southeast. Cooler marine layer to spread well inland given synoptic northwest winds. High pressure will settle over the area tonight providing another cool night with light winds. Lows expected to dip back to around 50 with some upper 40s likely in rural areas but warmer readings near the lake. && .LONG TERM...(Saturday through Thursday) Issued at 351 AM EDT Fri Jul 1 2016 High pressure to be centered over the region Saturday with very comfortable temperatures and humidity levels. This high will slide east over the weekend as front to our south tries to lift back north as a warm front. 00z models continued trend of keeping this boundary south again with dry easterly flow dominating from retreating high. Still some concern front could move farther north as previous model runs indicated but did side toward consensus blends with pop gradient over the forecast area. Highest chance pops in the south Sunday into Monday but kept far northern areas pcpn free for the holiday weekend. Heavy rain potential just south of our area and this will need to be watched closely for any northward shift. This deeper convection in models is cutting off moisture transport north thus limiting northward expansion of pcpn shield. Increasing moisture and another warm frontal push indicated in some of the medium range models by mid week. GFS remains an outlier compared to ECMWF and GEM which seem to be in decent agreement with each other. Blended guidance leads to low chance pops through much of next week but did try to keep some periods dry per latest guidance. Confidence remains low on timing of pcpn chances next week. Heat and humidity does look to build back by mid to late week as upper ridge strengthens and potential for temps climbing well into 90s with warmer solutions. Some heavy rain potential as well depending on where warm front ends up and location of any convective systems riding the boundary. && .AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon) Issued at 116 PM EDT Fri Jul 1 2016 As of 1730Z this afternoon a cold front was drifting southeast of the TAF sites with high pressure building in its wake. Large scale subsidence and gradual drying will continue to scour out remaining MVFR cloud decks by late afternoon. Northwest winds gusting as high as 25 knots will begin to diminish towards the evening hours as well. Expect VFR conditions tonight and Saturday. && .IWX Watches/Warnings/Advisories... IN...Beach Hazards Statement through Saturday morning for INZ003. MI...Beach Hazards Statement through Saturday morning for MIZ077. OH...NONE. LM...Small Craft Advisory until 8 AM EDT Saturday for LMZ043-046. && $$ SYNOPSIS...MCD SHORT TERM...Lashley LONG TERM...Lashley AVIATION...MCD Visit us at www.weather.gov/iwx Follow us on Facebook...Twitter...and YouTube at: www.facebook.com/NWSNorthernIndiana www.twitter.com/nwsiwx www.youtube.com/NWSNorthernIndiana
Area Forecast Discussion National Weather Service Northern Indiana 121 PM EDT FRI JUL 1 2016 .SYNOPSIS... Issued at 116 PM EDT Fri Jul 1 2016 High pressure will build into the area overnight and Saturday. Gusty northwest winds and any remaining cloud cover will gradually diminish by this evening. Afternoon highs will be in the upper 60s and 70s. Under clear skies, low temperatures tonight will drop into the 50s. There is a high swim risk for Lake Michigan beaches through tonight. Conditions will be life threatening to anyone who enters the water. && .SHORT TERM...(Today and Tonight) Issued at 351 AM EDT Fri Jul 1 2016 Short wave rotating through the Great Lakes early this morning was responsible for a broken line of showers and a few isolated thunderstorms ahead of associated sfc cold front. These showers and the cold front should move steadily east and exit the far eastern portions of NW Ohio counties around or shortly after 12z. Clearing looks to quickly follow with IR satellite showing clearing skies immediately behind front and water vapor showing substantial drying/subsidence. Skies expected to become mostly sunny with another cool and comfortable day in store for beginning of July. Highs will range from 60s near Lake Michigan to middle and upper 70s over the far south and southeast. Cooler marine layer to spread well inland given synoptic northwest winds. High pressure will settle over the area tonight providing another cool night with light winds. Lows expected to dip back to around 50 with some upper 40s likely in rural areas but warmer readings near the lake. && .LONG TERM...(Saturday through Thursday) Issued at 351 AM EDT Fri Jul 1 2016 High pressure to be centered over the region Saturday with very comfortable temperatures and humidity levels. This high will slide east over the weekend as front to our south tries to lift back north as a warm front. 00z models continued trend of keeping this boundary south again with dry easterly flow dominating from retreating high. Still some concern front could move farther north as previous model runs indicated but did side toward consensus blends with pop gradient over the forecast area. Highest chance pops in the south Sunday into Monday but kept far northern areas pcpn free for the holiday weekend. Heavy rain potential just south of our area and this will need to be watched closely for any northward shift. This deeper convection in models is cutting off moisture transport north thus limiting northward expansion of pcpn shield. Increasing moisture and another warm frontal push indicated in some of the medium range models by mid week. GFS remains an outlier compared to ECMWF and GEM which seem to be in decent agreement with each other. Blended guidance leads to low chance pops through much of next week but did try to keep some periods dry per latest guidance. Confidence remains low on timing of pcpn chances next week. Heat and humidity does look to build back by mid to late week as upper ridge strengthens and potential for temps climbing well into 90s with warmer solutions. Some heavy rain potential as well depending on where warm front ends up and location of any convective systems riding the boundary. && .AVIATION...(For the 18Z TAFS through 18Z Saturday Afternoon) Issued at 116 PM EDT Fri Jul 1 2016 As of 1730Z this afternoon a cold front was drifting southeast of the TAF sites with high pressure building in its wake. Large scale subsidence and gradual drying will continue to scour out remaining MVFR cloud decks by late afternoon. Northwest winds gusting as high as 25 knots will begin to diminish towards the evening hours as well. Expect VFR conditions tonight and Saturday. && .IWX Watches/Warnings/Advisories... IN...Beach Hazards Statement through Saturday morning for INZ003. MI...Beach Hazards Statement through Saturday morning for MIZ077. OH...NONE. LM...Small Craft Advisory until 8 AM EDT Saturday for LMZ043-046. && $$ SYNOPSIS...MCD SHORT TERM...Lashley LONG TERM...Lashley AVIATION...MCD Visit us at www.weather.gov/iwx Follow us on Facebook...Twitter...and YouTube at: www.facebook.com/NWSNorthernIndiana www.twitter.com/nwsiwx www.youtube.com/NWSNorthernIndiana
Area Forecast Discussion National Weather Service Indianapolis IN 1219 PM EDT FRI JUL 1 2016 .UPDATE... The AVIATION section has been updated below. && .SYNOPSIS... Issued at 355 AM EDT Fri Jul 1 2016 A cold front will move quickly through the area this morning and may bring a few showers and storms. High pressure will then return with dry pleasant weather into Saturday. A much more unsettled and active pattern sets up beginning Sunday through the early part of next week as the front returns back into the region and becomes nearly stationary. Warmer weather will arrive later next week along with the potential for more storms as central Indiana resides on the edge of an expanding upper ridge. && .NEAR TERM /Rest of Today/... Issued at 920 AM EDT Fri Jul 1 2016 Update...Showers and thunderstorms had just about ended across our forecast area. The only area remaining was far southern Daviess.. Martin...Lawrence and Jackson counties. Could see a POP up shower south for another hour or two. The main update...will be to drop the early morning part of forecast. Surface chart indicated cold front extended from near Richmond to just south of Sullivan at 1300Z. Tweaked temperatures and rest of near term slightly. But overall everything is on track. Portion of previous near term discussion follows... Any rain will be gone by midday as the upper wave and surface front quickly move off to the southeast and are replaced by a renewed surge of drier air and deep subsidence. Water vapor imagery showing a slug of very dry air currently present across the mid Mississippi Valley. Expect this to advect into the area by late morning with sunshine increasing as the day progresses. Mainly clear skies are expected by late afternoon as high pressure builds into the area. Temps...expect temps to warm nicely this afternoon in the drier airmass. Trended towards warmer METMOS which was supported by forecast low level thermals. Should see highs ranging from he mid 70s into the lower 80s most locales. && .SHORT TERM /Tonight through Sunday Night/... Issued at 355 AM EDT Fri Jul 1 2016 Forecast challenges focus on increasing threats for locally heavy rainfall by late weekend as the front returns north into the region and becomes quasi-stationary. Initially...high pressure will maintain dry pleasant weather through most of Saturday as it drifts slowly through the Ohio Valley. Model soundings and RH progs show the deeper layer of subsidence remaining over the region into Saturday...aided by low level flow veering from northerly to E/NE. Chances for rain will slowly increase from the southwest Saturday afternoon and night as moisture and isentropic lift arrive into the region. The drier airmass will be slow to saturate however with more widespread rain holding off for many until near or after daybreak Sunday. Upper energy currently over the Four Corners region will eject out into the central Plains on Saturday then shift east into the Ohio Valley by Sunday. Additional upper waves will follow as an easterly flow aloft aligns between a flat but strong ridge across the far southern part of the country and deeper upper lows along the western and eastern Canadian coasts. This will draw moisture with a Pacific origin east into the central Plains...mid Mississippi Valley and Ohio Valley. At the same time...southwest low level flow will develop around the back side of the Bermuda high and transport rich tropical Gulf moisture into these same regions for the second half of the weekend into early next week. The remnant frontal boundary will be drawn back north in response to the waves aloft kicking out to the east...and will serve as a focusing mechanism for repeated rounds of locally heavy rainfall beginning in the central Plains Saturday and shifting east into the Ohio Valley for Sunday and Monday. To the chagrin of many...confidence continues to grow in negative impacts for those with outdoor plans both Sunday and Monday as the frontal boundary will likely set up somewhere across the southern portions of Illinois and Indiana. The exact location of where the boundary ends up will be a big factor in where the heavy rain axis aligns. With that being said...numerous factors are strongly suggestive of a period of moderate to locally heavy rainfall focused from late Sunday afternoon into Sunday night and for some...likely persisting into Independence Day. The dual moisture surges coming from both the Pacific and Gulf will produce an impressive axis of high precip water values at 2 to 3 standard deviations above normal for July...in excess of 2 inches across much of central Indiana. Precip efficiency is maximized along and south of the I-70 corridor as deep convergence up to 700mb organizes at the nose of a 40-45kt low level jet Sunday afternoon and night. Strong frontogenetical forcing and diffluence aloft are also present along the boundary and should further enhance rainfall coverage and intensity Sunday night. Feel comfortable raising pops for the entire area and focusing the highest pops at this time along and south of the I-70 corridor for Sunday and Sunday night. There are still likely to be some fluctuations in the heaviest rainfall and where the frontal boundary aligns but as discussed above...numerous signals supporting the mention of heavy rainfall for the southern 2/3 of the forecast area late Sunday into Sunday night. The severe threat south of the front should largely remain just south of the forecast area...but again any northward bump to the boundary would bring that possibility into play for Sunday and Sunday night. Lots still to work out in the coming 24-48 hours ahead of the rain. Temps...felt a model blend generally handled highs and lows well through the period. With the rain/storms and clouds on Sunday... there exists a real possibility that highs have a difficult time even making it to 70 in some locations. The record for coolest high for July 3 is 70 at Indy from 1924 and that could be in jeopardy. && .LONG TERM /Monday through next Thursday/... Issued at 236 AM EDT Fri Jul 1 2016 Ensembles suggest system that is expected to affect the area during the tail end of the short term will will in the process of passing off to the east early next week. Will keep PoPs going in the forecast for Monday into Tuesday to cover this system. By the middle of next week, ensembles agree on shifting heat ridge eastward more towards the Plains and Midwest, but there are differences in how aggressive this ridge builds into the local area. Some ensembles suggest ridge will build over the Ohio Valley, effectively capping off convective threat by the middle of next week, while others keep the center of the ridge more over the southern Plains. This would allow for the potential for periodic convective clusters along the edge of the heat ridge to affect the area. For now, will keep some small chance PoPs in the forecast for next Wednesday and Thursday to cover this possibility. && .AVIATION /Discussion for the 011800Z TAF Issuance/... Issued at 1219 PM EDT Fri Jul 1 2016 VFR conditions expected through the period. Broken cumulus field will have lifted to VFR levels by valid time, and this field will break up during the afternoon as subsidence develops over the area. Otherwise a gradual increase in high and eventually mid cloud can be expected. North winds around 10kt (perhaps some gusts to 15kt) this afternoon will diminish around sunset, then become light east by Saturday morning. && .IND Watches/Warnings/Advisories... NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN/JH SHORT TERM...RYAN LONG TERM....JAS AVIATION...50
Area Forecast Discussion National Weather Service Indianapolis IN 1023 AM EDT FRI JUL 1 2016 .UPDATE... The AVIATION section has been updated below. && .SYNOPSIS... Issued at 355 AM EDT Fri Jul 1 2016 A cold front will move quickly through the area this morning and may bring a few showers and storms. High pressure will then return with dry pleasant weather into Saturday. A much more unsettled and active pattern sets up beginning Sunday through the early part of next week as the front returns back into the region and becomes nearly stationary. Warmer weather will arrive later next week along with the potential for more storms as central Indiana resides on the edge of an expanding upper ridge. && .NEAR TERM /Rest of Today/... Issued at 920 AM EDT Fri Jul 1 2016 Update...Showers and thunderstorms had just about ended across our forecast area. The only area remaining was far southern Daviess.. Martin...Lawrence and Jackson counties. Could see a POP up shower south for another hour or two. The main update...will be to drop the early morning part of forecast. Surface chart indicated cold front extended from near Richmond to just south of Sullivan at 1300Z. Tweaked temperatures and rest of near term slightly. But overall everything is on track. Portion of previous near term discussion follows... Any rain will be gone by midday as the upper wave and surface front quickly move off to the southeast and are replaced by a renewed surge of drier air and deep subsidence. Water vapor imagery showing a slug of very dry air currently present across the mid Mississippi Valley. Expect this to advect into the area by late morning with sunshine increasing as the day progresses. Mainly clear skies are expected by late afternoon as high pressure builds into the area. Temps...expect temps to warm nicely this afternoon in the drier airmass. Trended towards warmer METMOS which was supported by forecast low level thermals. Should see highs ranging from he mid 70s into the lower 80s most locales. && .SHORT TERM /Tonight through Sunday Night/... Issued at 355 AM EDT Fri Jul 1 2016 Forecast challenges focus on increasing threats for locally heavy rainfall by late weekend as the front returns north into the region and becomes quasi-stationary. Initially...high pressure will maintain dry pleasant weather through most of Saturday as it drifts slowly through the Ohio Valley. Model soundings and RH progs show the deeper layer of subsidence remaining over the region into Saturday...aided by low level flow veering from northerly to E/NE. Chances for rain will slowly increase from the southwest Saturday afternoon and night as moisture and isentropic lift arrive into the region. The drier airmass will be slow to saturate however with more widespread rain holding off for many until near or after daybreak Sunday. Upper energy currently over the Four Corners region will eject out into the central Plains on Saturday then shift east into the Ohio Valley by Sunday. Additional upper waves will follow as an easterly flow aloft aligns between a flat but strong ridge across the far southern part of the country and deeper upper lows along the western and eastern Canadian coasts. This will draw moisture with a Pacific origin east into the central Plains...mid Mississippi Valley and Ohio Valley. At the same time...southwest low level flow will develop around the back side of the Bermuda high and transport rich tropical Gulf moisture into these same regions for the second half of the weekend into early next week. The remnant frontal boundary will be drawn back north in response to the waves aloft kicking out to the east...and will serve as a focusing mechanism for repeated rounds of locally heavy rainfall beginning in the central Plains Saturday and shifting east into the Ohio Valley for Sunday and Monday. To the chagrin of many...confidence continues to grow in negative impacts for those with outdoor plans both Sunday and Monday as the frontal boundary will likely set up somewhere across the southern portions of Illinois and Indiana. The exact location of where the boundary ends up will be a big factor in where the heavy rain axis aligns. With that being said...numerous factors are strongly suggestive of a period of moderate to locally heavy rainfall focused from late Sunday afternoon into Sunday night and for some...likely persisting into Independence Day. The dual moisture surges coming from both the Pacific and Gulf will produce an impressive axis of high precip water values at 2 to 3 standard deviations above normal for July...in excess of 2 inches across much of central Indiana. Precip efficiency is maximized along and south of the I-70 corridor as deep convergence up to 700mb organizes at the nose of a 40-45kt low level jet Sunday afternoon and night. Strong frontogenetical forcing and diffluence aloft are also present along the boundary and should further enhance rainfall coverage and intensity Sunday night. Feel comfortable raising pops for the entire area and focusing the highest pops at this time along and south of the I-70 corridor for Sunday and Sunday night. There are still likely to be some fluctuations in the heaviest rainfall and where the frontal boundary aligns but as discussed above...numerous signals supporting the mention of heavy rainfall for the southern 2/3 of the forecast area late Sunday into Sunday night. The severe threat south of the front should largely remain just south of the forecast area...but again any northward bump to the boundary would bring that possibility into play for Sunday and Sunday night. Lots still to work out in the coming 24-48 hours ahead of the rain. Temps...felt a model blend generally handled highs and lows well through the period. With the rain/storms and clouds on Sunday... there exists a real possibility that highs have a difficult time even making it to 70 in some locations. The record for coolest high for July 3 is 70 at Indy from 1924 and that could be in jeopardy. && .LONG TERM /Monday through next Thursday/... Issued at 236 AM EDT Fri Jul 1 2016 Ensembles suggest system that is expected to affect the area during the tail end of the short term will will in the process of passing off to the east early next week. Will keep PoPs going in the forecast for Monday into Tuesday to cover this system. By the middle of next week, ensembles agree on shifting heat ridge eastward more towards the Plains and Midwest, but there are differences in how aggressive this ridge builds into the local area. Some ensembles suggest ridge will build over the Ohio Valley, effectively capping off convective threat by the middle of next week, while others keep the center of the ridge more over the southern Plains. This would allow for the potential for periodic convective clusters along the edge of the heat ridge to affect the area. For now, will keep some small chance PoPs in the forecast for next Wednesday and Thursday to cover this possibility. && .AVIATION /Discussion for the 011500Z TAF Update/... Issued at 1023 AM EDT Fri Jul 1 2016 Based on upstream conditions, added an hour to the length of the TEMPO MVFR conditions at KIND, and lowered the ceiling to 2000ft. Wouldn`t be surprised if brief ceilings below 2000ft were observed. Upped wind speed as well based on current conditions. Previous discussion follows... Convective activity that had impacted KLAF earlier has moved off to the east, while the rest of the activity upstream is diminishing in intensity. Lightning potential in the vicinity of the terminals doesn`t look too impressive this morning, however threat for scattered showers will linger into the mid to late morning hours as a cold front drops through. Could be a period of MVFR ceilings 015-025 in the wake of frontal passage through midday, but with quite a bit of dry air upstream, ceilings should scatter out this afternoon. Surface winds expected to veer around to 320-350 degrees by mid to late morning as front passes by, with speeds 9-12 kts. && .IND Watches/Warnings/Advisories... NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN/JH SHORT TERM...RYAN LONG TERM....JAS AVIATION...JAS/50
Area Forecast Discussion National Weather Service Indianapolis IN 920 AM EDT FRI JUL 1 2016 .UPDATE... Near term for the rest of today has been updated below. && .SYNOPSIS... Issued at 355 AM EDT Fri Jul 1 2016 A cold front will move quickly through the area this morning and may bring a few showers and storms. High pressure will then return with dry pleasant weather into Saturday. A much more unsettled and active pattern sets up beginning Sunday through the early part of next week as the front returns back into the region and becomes nearly stationary. Warmer weather will arrive later next week along with the potential for more storms as central Indiana resides on the edge of an expanding upper ridge. && .NEAR TERM /Rest of Today/... Issued at 920 AM EDT Fri Jul 1 2016 .Update...Showers and thunderstorms had just about ended across our forecast area. The only area remaining was far southern Daviess.. Martin...Lawrence and Jackson counties. Could see a POP up shower south for another hour or two. The main update...will be to drop the early morning part of foreast. Surface chart indicated cold front extended from near Richmond to just south of Sullivan at 1300Z. Tweaked temperatures and rest of near term slightly. But overall everything is on track. Portion of previous near term discussion follows... Any rain will be gone by midday as the upper wave and surface front quickly move off to the southeast and are replaced by a renewed surge of drier air and deep subsidence. Water vapor imagery showing a slug of very dry air currently present across the mid Mississippi Valley. Expect this to advect into the area by late morning with sunshine increasing as the day progresses. Mainly clear skies are expected by late afternoon as high pressure builds into the area. Temps...expect temps to warm nicely this afternoon in the drier airmass. Trended towards warmer METMOS which was supported by forecast low level thermals. Should see highs ranging from he mid 70s into the lower 80s most locales. && .SHORT TERM /Tonight through Sunday Night/... Issued at 355 AM EDT Fri Jul 1 2016 Forecast challenges focus on increasing threats for locally heavy rainfall by late weekend as the front returns north into the region and becomes quasi-stationary. Initially...high pressure will maintain dry pleasant weather through most of Saturday as it drifts slowly through the Ohio Valley. Model soundings and RH progs show the deeper layer of subsidence remaining over the region into Saturday...aided by low level flow veering from northerly to E/NE. Chances for rain will slowly increase from the southwest Saturday afternoon and night as moisture and isentropic lift arrive into the region. The drier airmass will be slow to saturate however with more widespread rain holding off for many until near or after daybreak Sunday. Upper energy currently over the Four Corners region will eject out into the central Plains on Saturday then shift east into the Ohio Valley by Sunday. Additional upper waves will follow as an easterly flow aloft aligns between a flat but strong ridge across the far southern part of the country and deeper upper lows along the western and eastern Canadian coasts. This will draw moisture with a Pacific origin east into the central Plains...mid Mississippi Valley and Ohio Valley. At the same time...southwest low level flow will develop around the back side of the Bermuda high and transport rich tropical Gulf moisture into these same regions for the second half of the weekend into early next week. The remnant frontal boundary will be drawn back north in response to the waves aloft kicking out to the east...and will serve as a focusing mechanism for repeated rounds of locally heavy rainfall beginning in the central Plains Saturday and shifting east into the Ohio Valley for Sunday and Monday. To the chagrin of many...confidence continues to grow in negative impacts for those with outdoor plans both Sunday and Monday as the frontal boundary will likely set up somewhere across the southern portions of Illinois and Indiana. The exact location of where the boundary ends up will be a big factor in where the heavy rain axis aligns. With that being said...numerous factors are strongly suggestive of a period of moderate to locally heavy rainfall focused from late Sunday afternoon into Sunday night and for some...likely persisting into Independence Day. The dual moisture surges coming from both the Pacific and Gulf will produce an impressive axis of high precip water values at 2 to 3 standard deviations above normal for July...in excess of 2 inches across much of central Indiana. Precip efficiency is maximized along and south of the I-70 corridor as deep convergence up to 700mb organizes at the nose of a 40-45kt low level jet Sunday afternoon and night. Strong frontogenetical forcing and diffluence aloft are also present along the boundary and should further enhance rainfall coverage and intensity Sunday night. Feel comfortable raising pops for the entire area and focusing the highest pops at this time along and south of the I-70 corridor for Sunday and Sunday night. There are still likely to be some fluctuations in the heaviest rainfall and where the frontal boundary aligns but as discussed above...numerous signals supporting the mention of heavy rainfall for the southern 2/3 of the forecast area late Sunday into Sunday night. The severe threat south of the front should largely remain just south of the forecast area...but again any northward bump to the boundary would bring that possibility into play for Sunday and Sunday night. Lots still to work out in the coming 24-48 hours ahead of the rain. Temps...felt a model blend generally handled highs and lows well through the period. With the rain/storms and clouds on Sunday... there exists a real possibility that highs have a difficult time even making it to 70 in some locations. The record for coolest high for July 3 is 70 at Indy from 1924 and that could be in jeopardy. && .LONG TERM /Monday through next Thursday/... Issued at 236 AM EDT Fri Jul 1 2016 Ensembles suggest system that is expected to affect the area during the tail end of the short term will will in the process of passing off to the east early next week. Will keep PoPs going in the forecast for Monday into Tuesday to cover this system. By the middle of next week, ensembles agree on shifting heat ridge eastward more towards the Plains and Midwest, but there are differences in how aggressive this ridge builds into the local area. Some ensembles suggest ridge will build over the Ohio Valley, effectively capping off convective threat by the middle of next week, while others keep the center of the ridge more over the southern Plains. This would allow for the potential for periodic convective clusters along the edge of the heat ridge to affect the area. For now, will keep some small chance PoPs in the forecast for next Wednesday and Thursday to cover this possibility. && .AVIATION /Discussion for the 011200Z TAFS/... Issued at 630 AM EDT Fri Jul 1 2016 Convective activity that had impacted KLAF earlier has moved off to the east, while the rest of the activity upstream is diminishing in intensity. Lightning potential in the vicinity of the terminals doesn`t look too impressive this morning, however threat for scattered showers will linger into the mid to late morning hours as a cold front drops through. Could be a period of MVFR ceilings 015-025 in the wake of frontal passage through midday, but with quite a bit of dry air upstream, ceilings should scatter out this afternoon. Surface winds expected to veer around to 320-350 degrees by mid to late morning as front passes by, with speeds 9-12 kts. && .IND Watches/Warnings/Advisories... NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN/JH SHORT TERM...RYAN LONG TERM....JAS AVIATION...JAS
Area Forecast Discussion National Weather Service Indianapolis IN 920 AM EDT FRI JUL 1 2016 .UPDATE... Near term for the rest of today has been updated below. && .SYNOPSIS... Issued at 355 AM EDT Fri Jul 1 2016 A cold front will move quickly through the area this morning and may bring a few showers and storms. High pressure will then return with dry pleasant weather into Saturday. A much more unsettled and active pattern sets up beginning Sunday through the early part of next week as the front returns back into the region and becomes nearly stationary. Warmer weather will arrive later next week along with the potential for more storms as central Indiana resides on the edge of an expanding upper ridge. && .NEAR TERM /Rest of Today/... Issued at 920 AM EDT Fri Jul 1 2016 .Update...Showers and thunderstorms had just about ended across our forecast area. The only area remaining was far southern Daviess.. Martin...Lawrence and Jackson counties. Could see a POP up shower south for another hour or two. The main update...will be to drop the early morning part of foreast. Surface chart indicated cold front extended from near Richmond to just south of Sullivan at 1300Z. Tweaked temperatures and rest of near term slightly. But overall everything is on track. Portion of previous near term discussion follows... Any rain will be gone by midday as the upper wave and surface front quickly move off to the southeast and are replaced by a renewed surge of drier air and deep subsidence. Water vapor imagery showing a slug of very dry air currently present across the mid Mississippi Valley. Expect this to advect into the area by late morning with sunshine increasing as the day progresses. Mainly clear skies are expected by late afternoon as high pressure builds into the area. Temps...expect temps to warm nicely this afternoon in the drier airmass. Trended towards warmer METMOS which was supported by forecast low level thermals. Should see highs ranging from he mid 70s into the lower 80s most locales. && .SHORT TERM /Tonight through Sunday Night/... Issued at 355 AM EDT Fri Jul 1 2016 Forecast challenges focus on increasing threats for locally heavy rainfall by late weekend as the front returns north into the region and becomes quasi-stationary. Initially...high pressure will maintain dry pleasant weather through most of Saturday as it drifts slowly through the Ohio Valley. Model soundings and RH progs show the deeper layer of subsidence remaining over the region into Saturday...aided by low level flow veering from northerly to E/NE. Chances for rain will slowly increase from the southwest Saturday afternoon and night as moisture and isentropic lift arrive into the region. The drier airmass will be slow to saturate however with more widespread rain holding off for many until near or after daybreak Sunday. Upper energy currently over the Four Corners region will eject out into the central Plains on Saturday then shift east into the Ohio Valley by Sunday. Additional upper waves will follow as an easterly flow aloft aligns between a flat but strong ridge across the far southern part of the country and deeper upper lows along the western and eastern Canadian coasts. This will draw moisture with a Pacific origin east into the central Plains...mid Mississippi Valley and Ohio Valley. At the same time...southwest low level flow will develop around the back side of the Bermuda high and transport rich tropical Gulf moisture into these same regions for the second half of the weekend into early next week. The remnant frontal boundary will be drawn back north in response to the waves aloft kicking out to the east...and will serve as a focusing mechanism for repeated rounds of locally heavy rainfall beginning in the central Plains Saturday and shifting east into the Ohio Valley for Sunday and Monday. To the chagrin of many...confidence continues to grow in negative impacts for those with outdoor plans both Sunday and Monday as the frontal boundary will likely set up somewhere across the southern portions of Illinois and Indiana. The exact location of where the boundary ends up will be a big factor in where the heavy rain axis aligns. With that being said...numerous factors are strongly suggestive of a period of moderate to locally heavy rainfall focused from late Sunday afternoon into Sunday night and for some...likely persisting into Independence Day. The dual moisture surges coming from both the Pacific and Gulf will produce an impressive axis of high precip water values at 2 to 3 standard deviations above normal for July...in excess of 2 inches across much of central Indiana. Precip efficiency is maximized along and south of the I-70 corridor as deep convergence up to 700mb organizes at the nose of a 40-45kt low level jet Sunday afternoon and night. Strong frontogenetical forcing and diffluence aloft are also present along the boundary and should further enhance rainfall coverage and intensity Sunday night. Feel comfortable raising pops for the entire area and focusing the highest pops at this time along and south of the I-70 corridor for Sunday and Sunday night. There are still likely to be some fluctuations in the heaviest rainfall and where the frontal boundary aligns but as discussed above...numerous signals supporting the mention of heavy rainfall for the southern 2/3 of the forecast area late Sunday into Sunday night. The severe threat south of the front should largely remain just south of the forecast area...but again any northward bump to the boundary would bring that possibility into play for Sunday and Sunday night. Lots still to work out in the coming 24-48 hours ahead of the rain. Temps...felt a model blend generally handled highs and lows well through the period. With the rain/storms and clouds on Sunday... there exists a real possibility that highs have a difficult time even making it to 70 in some locations. The record for coolest high for July 3 is 70 at Indy from 1924 and that could be in jeopardy. && .LONG TERM /Monday through next Thursday/... Issued at 236 AM EDT Fri Jul 1 2016 Ensembles suggest system that is expected to affect the area during the tail end of the short term will will in the process of passing off to the east early next week. Will keep PoPs going in the forecast for Monday into Tuesday to cover this system. By the middle of next week, ensembles agree on shifting heat ridge eastward more towards the Plains and Midwest, but there are differences in how aggressive this ridge builds into the local area. Some ensembles suggest ridge will build over the Ohio Valley, effectively capping off convective threat by the middle of next week, while others keep the center of the ridge more over the southern Plains. This would allow for the potential for periodic convective clusters along the edge of the heat ridge to affect the area. For now, will keep some small chance PoPs in the forecast for next Wednesday and Thursday to cover this possibility. && .AVIATION /Discussion for the 011200Z TAFS/... Issued at 630 AM EDT Fri Jul 1 2016 Convective activity that had impacted KLAF earlier has moved off to the east, while the rest of the activity upstream is diminishing in intensity. Lightning potential in the vicinity of the terminals doesn`t look too impressive this morning, however threat for scattered showers will linger into the mid to late morning hours as a cold front drops through. Could be a period of MVFR ceilings 015-025 in the wake of frontal passage through midday, but with quite a bit of dry air upstream, ceilings should scatter out this afternoon. Surface winds expected to veer around to 320-350 degrees by mid to late morning as front passes by, with speeds 9-12 kts. && .IND Watches/Warnings/Advisories... NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN/JH SHORT TERM...RYAN LONG TERM....JAS AVIATION...JAS
Area Forecast Discussion National Weather Service Northern Indiana 656 AM EDT FRI JUL 1 2016 .SYNOPSIS... Issued at 352 AM EDT Fri Jul 1 2016 A cold front will push through the region this morning. Scattered showers and a few thunderstorms ahead of this front will quickly exit the east early today. Skies will then clear behind the cold front as high pressure builds back into the area. It will be a mild and comfortable day with highs ranging from the upper 60s near Lake Michigan...to the middle and upper 70s over northwest Ohio. Clear skies and light winds tonight will allow low temperatures to drop into the upper 40s and lower 50s. && .SHORT TERM...(Today and Tonight) Issued at 351 AM EDT Fri Jul 1 2016 Short wave rotating through the Great Lakes early this morning was responsible for a broken line of showers and a few isolated thunderstorms ahead of associated sfc cold front. These showers and the cold front should move steadily east and exit the far eastern portions of NW Ohio counties around or shortly after 12z. Clearing looks to quickly follow with IR satellite showing clearing skies immediately behind front and water vapor showing substantial drying/subsidence. Skies expected to become mostly sunny with another cool and comfortable day in store for beginning of July. Highs will range from 60s near Lake Michigan to middle and upper 70s over the far south and southeast. Cooler marine layer to spread well inland given synoptic northwest winds. High pressure will settle over the area tonight providing another cool night with light winds. Lows expected to dip back to around 50 with some upper 40s likely in rural areas but warmer readings near the lake. && .LONG TERM...(Saturday through Thursday) Issued at 351 AM EDT Fri Jul 1 2016 High pressure to be centered over the region Saturday with very comfortable temperatures and humidity levels. This high will slide east over the weekend as front to our south tries to lift back north as a warm front. 00z models continued trend of keeping this boundary south again with dry easterly flow dominating from retreating high. Still some concern front could move farther north as previous model runs indicated but did side toward consensus blends with pop gradient over the forecast area. Highest chance pops in the south Sunday into Monday but kept far northern areas pcpn free for the holiday weekend. Heavy rain potential just south of our area and this will need to be watched closely for any northward shift. This deeper convection in models is cutting off moisture transport north thus limiting northward expansion of pcpn shield. Increasing moisture and another warm frontal push indicated in some of the medium range models by mid week. GFS remains an outlier compared to ECMWF and GEM which seem to be in decent agreement with each other. Blended guidance leads to low chance pops through much of next week but did try to keep some periods dry per latest guidance. Confidence remains low on timing of pcpn chances next week. Heat and humidity does look to build back by mid to late week as upper ridge strengthens and potential for temps climbing well into 90s with warmer solutions. Some heavy rain potential as well depending on where warm front ends up and location of any convective systems riding the boundary. && .AVIATION...(For the 12Z TAFS through 12Z Saturday Morning) Issued at 652 AM EDT Fri Jul 1 2016 Primarily anticipating VFR conds through the period for northern Indiana. Only exception perhaps a brief fuel/alternate criteria cigs initial hour or two at/near KSBN until deeper mixing promotes lifting ceilings. Thereafter...cloud coverage/bases to quickly mixout more/higher with afternoon dissipation trend coincident with progressive moisture scour through midday/afternoon. && .IWX Watches/Warnings/Advisories... IN...Beach Hazards Statement through Saturday morning for INZ003. MI...Beach Hazards Statement through Saturday morning for MIZ077. OH...NONE. LM...Small Craft Advisory until 8 AM EDT Saturday for LMZ043-046. && $$ SYNOPSIS...Lashley SHORT TERM...Lashley LONG TERM...Lashley AVIATION...Murphy Visit us at www.weather.gov/iwx Follow us on Facebook...Twitter...and YouTube at: www.facebook.com/NWSNorthernIndiana www.twitter.com/nwsiwx www.youtube.com/NWSNorthernIndiana
Area Forecast Discussion National Weather Service Indianapolis IN 631 AM EDT FRI JUL 1 2016 .UPDATE... The AVIATION Section has been updated below. && .SYNOPSIS... Issued at 355 AM EDT Fri Jul 1 2016 A cold front will move quickly through the area this morning and may bring a few showers and storms. High pressure will then return with dry pleasant weather into Saturday. A much more unsettled and active pattern sets up beginning Sunday through the early part of next week as the front returns back into the region and becomes nearly stationary. Warmer weather will arrive later next week along with the potential for more storms as central Indiana resides on the edge of an expanding upper ridge. && .NEAR TERM /Today/... Issued at 355 AM EDT Fri Jul 1 2016 Plenty of clouds present over central Indiana early this morning as a cold front moves into the region from the northwest. Scattered convection has gradually increased in coverage over the last few hours in the vicinity of the boundary over northwest Indiana back into central Illinois. 07Z temps ranged from the mid 60s to the lower 70s. Primary focus for today is on precip chances during the morning as the front sweeps across the forecast area. Weak lift along and immediately ahead of the front and subtle instability will be the main drivers of showers and storms through the next several hours but with limited moisture and little forcing aloft...hard to justify more than chance pops through the morning hours. Hi-res guidance has this thinking captured well...led by the WRF with the HRRR playing catchup. Any rain will be gone by midday as the upper wave and surface front quickly move off to the southeast and are replaced by a renewed surge of drier air and deep subsidence. Water vapor imagery showing a slug of very dry air currently present across the mid Mississippi Valley. Expect this to advect into the area by late morning with sunshine increasing as the day progresses. Mainly clear skies are expected by late afternoon as high pressure builds into the area. Temps...expect temps to warm nicely this afternoon in the drier airmass. Trended towards warmer METMOS which was supported by forecast low level thermals. Should see highs ranging from he mid 70s into the lower 80s most locales. && .SHORT TERM /Tonight through Sunday Night/... Issued at 355 AM EDT Fri Jul 1 2016 Forecast challenges focus on increasing threats for locally heavy rainfall by late weekend as the front returns north into the region and becomes quasi-stationary. Initially...high pressure will maintain dry pleasant weather through most of Saturday as it drifts slowly through the Ohio Valley. Model soundings and RH progs show the deeper layer of subsidence remaining over the region into Saturday...aided by low level flow veering from northerly to E/NE. Chances for rain will slowly increase from the southwest Saturday afternoon and night as moisture and isentropic lift arrive into the region. The drier airmass will be slow to saturate however with more widespread rain holding off for many until near or after daybreak Sunday. Upper energy currently over the Four Corners region will eject out into the central Plains on Saturday then shift east into the Ohio Valley by Sunday. Additional upper waves will follow as an easterly flow aloft aligns between a flat but strong ridge across the far southern part of the country and deeper upper lows along the western and eastern Canadian coasts. This will draw moisture with a Pacific origin east into the central Plains...mid Mississippi Valley and Ohio Valley. At the same time...southwest low level flow will develop around the back side of the Bermuda high and transport rich tropical Gulf moisture into these same regions for the second half of the weekend into early next week. The remnant frontal boundary will be drawn back north in response to the waves aloft kicking out to the east...and will serve as a focusing mechanism for repeated rounds of locally heavy rainfall beginning in the central Plains Saturday and shifting east into the Ohio Valley for Sunday and Monday. To the chagrin of many...confidence continues to grow in negative impacts for those with outdoor plans both Sunday and Monday as the frontal boundary will likely set up somewhere across the southern portions of Illinois and Indiana. The exact location of where the boundary ends up will be a big factor in where the heavy rain axis aligns. With that being said...numerous factors are strongly suggestive of a period of moderate to locally heavy rainfall focused from late Sunday afternoon into Sunday night and for some...likely persisting into Independence Day. The dual moisture surges coming from both the Pacific and Gulf will produce an impressive axis of high precip water values at 2 to 3 standard deviations above normal for July...in excess of 2 inches across much of central Indiana. Precip efficiency is maximized along and south of the I-70 corridor as deep convergence up to 700mb organizes at the nose of a 40-45kt low level jet Sunday afternoon and night. Strong frontogenetical forcing and diffluence aloft are also present along the boundary and should further enhance rainfall coverage and intensity Sunday night. Feel comfortable raising pops for the entire area and focusing the highest pops at this time along and south of the I-70 corridor for Sunday and Sunday night. There are still likely to be some fluctuations in the heaviest rainfall and where the frontal boundary aligns but as discussed above...numerous signals supporting the mention of heavy rainfall for the southern 2/3 of the forecast area late Sunday into Sunday night. The severe threat south of the front should largely remain just south of the forecast area...but again any northward bump to the boundary would bring that possibility into play for Sunday and Sunday night. Lots still to work out in the coming 24-48 hours ahead of the rain. Temps...felt a model blend generally handled highs and lows well through the period. With the rain/storms and clouds on Sunday... there exists a real possibility that highs have a difficult time even making it to 70 in some locations. The record for coolest high for July 3 is 70 at Indy from 1924 and that could be in jeopardy. && .LONG TERM /Monday through next Thursday/... Issued at 236 AM EDT Fri Jul 1 2016 Ensembles suggest system that is expected to affect the area during the tail end of the short term will will in the process of passing off to the east early next week. Will keep PoPs going in the forecast for Monday into Tuesday to cover this system. By the middle of next week, ensembles agree on shifting heat ridge eastward more towards the Plains and Midwest, but there are differences in how aggressive this ridge builds into the local area. Some ensembles suggest ridge will build over the Ohio Valley, effectively capping off convective threat by the middle of next week, while others keep the center of the ridge more over the southern Plains. This would allow for the potential for periodic convective clusters along the edge of the heat ridge to affect the area. For now, will keep some small chance PoPs in the forecast for next Wednesday and Thursday to cover this possibility. && .AVIATION /Discussion for the 011200Z TAFS/... Issued at 630 AM EDT Fri Jul 1 2016 Convective activity that had impacted KLAF earlier has moved off to the east, while the rest of the activity upstream is diminishing in intensity. Lightning potential in the vicinity of the terminals doesn`t look too impressive this morning, however threat for scattered showers will linger into the mid to late morning hours as a cold front drops through. Could be a period of MVFR ceilings 015-025 in the wake of frontal passage through midday, but with quite a bit of dry air upstream, ceilings should scatter out this afternoon. Surface winds expected to veer around to 320-350 degrees by mid to late morning as front passes by, with speeds 9-12 kts. && .IND Watches/Warnings/Advisories... NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN SHORT TERM...RYAN LONG TERM....JAS AVIATION...JAS
Area Forecast Discussion National Weather Service Indianapolis IN 428 AM EDT FRI JUL 1 2016 .UPDATE... The AVIATION Section has been updated below. && .SYNOPSIS... Issued at 355 AM EDT Fri Jul 1 2016 A cold front will move quickly through the area this morning and may bring a few showers and storms. High pressure will then return with dry pleasant weather into Saturday. A much more unsettled and active pattern sets up beginning Sunday through the early part of next week as the front returns back into the region and becomes nearly stationary. Warmer weather will arrive later next week along with the potential for more storms as central Indiana resides on the edge of an expanding upper ridge. && .NEAR TERM /Today/... Issued at 355 AM EDT Fri Jul 1 2016 Plenty of clouds present over central Indiana early this morning as a cold front moves into the region from the northwest. Scattered convection has gradually increased in coverage over the last few hours in the vicinity of the boundary over northwest Indiana back into central Illinois. 07Z temps ranged from the mid 60s to the lower 70s. Primary focus for today is on precip chances during the morning as the front sweeps across the forecast area. Weak lift along and immediately ahead of the front and subtle instability will be the main drivers of showers and storms through the next several hours but with limited moisture and little forcing aloft...hard to justify more than chance pops through the morning hours. Hi-res guidance has this thinking captured well...led by the WRF with the HRRR playing catchup. Any rain will be gone by midday as the upper wave and surface front quickly move off to the southeast and are replaced by a renewed surge of drier air and deep subsidence. Water vapor imagery showing a slug of very dry air currently present across the mid Mississippi Valley. Expect this to advect into the area by late morning with sunshine increasing as the day progresses. Mainly clear skies are expected by late afternoon as high pressure builds into the area. Temps...expect temps to warm nicely this afternoon in the drier airmass. Trended towards warmer METMOS which was supported by forecast low level thermals. Should see highs ranging from he mid 70s into the lower 80s most locales. && .SHORT TERM /Tonight through Sunday Night/... Issued at 355 AM EDT Fri Jul 1 2016 Forecast challenges focus on increasing threats for locally heavy rainfall by late weekend as the front returns north into the region and becomes quasi-stationary. Initially...high pressure will maintain dry pleasant weather through most of Saturday as it drifts slowly through the Ohio Valley. Model soundings and RH progs show the deeper layer of subsidence remaining over the region into Saturday...aided by low level flow veering from northerly to E/NE. Chances for rain will slowly increase from the southwest Saturday afternoon and night as moisture and isentropic lift arrive into the region. The drier airmass will be slow to saturate however with more widespread rain holding off for many until near or after daybreak Sunday. Upper energy currently over the Four Corners region will eject out into the central Plains on Saturday then shift east into the Ohio Valley by Sunday. Additional upper waves will follow as an easterly flow aloft aligns between a flat but strong ridge across the far southern part of the country and deeper upper lows along the western and eastern Canadian coasts. This will draw moisture with a Pacific origin east into the central Plains...mid Mississippi Valley and Ohio Valley. At the same time...southwest low level flow will develop around the back side of the Bermuda high and transport rich tropical Gulf moisture into these same regions for the second half of the weekend into early next week. The remnant frontal boundary will be drawn back north in response to the waves aloft kicking out to the east...and will serve as a focusing mechanism for repeated rounds of locally heavy rainfall beginning in the central Plains Saturday and shifting east into the Ohio Valley for Sunday and Monday. To the chagrin of many...confidence continues to grow in negative impacts for those with outdoor plans both Sunday and Monday as the frontal boundary will likely set up somewhere across the southern portions of Illinois and Indiana. The exact location of where the boundary ends up will be a big factor in where the heavy rain axis aligns. With that being said...numerous factors are strongly suggestive of a period of moderate to locally heavy rainfall focused from late Sunday afternoon into Sunday night and for some...likely persisting into Independence Day. The dual moisture surges coming from both the Pacific and Gulf will produce an impressive axis of high precip water values at 2 to 3 standard deviations above normal for July...in excess of 2 inches across much of central Indiana. Precip efficiency is maximized along and south of the I-70 corridor as deep convergence up to 700mb organizes at the nose of a 40-45kt low level jet Sunday afternoon and night. Strong frontogenetical forcing and diffluence aloft are also present along the boundary and should further enhance rainfall coverage and intensity Sunday night. Feel comfortable raising pops for the entire area and focusing the highest pops at this time along and south of the I-70 corridor for Sunday and Sunday night. There are still likely to be some fluctuations in the heaviest rainfall and where the frontal boundary aligns but as discussed above...numerous signals supporting the mention of heavy rainfall for the southern 2/3 of the forecast area late Sunday into Sunday night. The severe threat south of the front should largely remain just south of the forecast area...but again any northward bump to the boundary would bring that possibility into play for Sunday and Sunday night. Lots still to work out in the coming 24-48 hours ahead of the rain. Temps...felt a model blend generally handled highs and lows well through the period. With the rain/storms and clouds on Sunday... there exists a real possibility that highs have a difficult time even making it to 70 in some locations. The record for coolest high for July 3 is 70 at Indy from 1924 and that could be in jeopardy. && .LONG TERM /Monday through next Thursday/... Issued at 236 AM EDT Fri Jul 1 2016 Ensembles suggest system that is expected to affect the area during the tail end of the short term will will in the process of passing off to the east early next week. Will keep PoPs going in the forecast for Monday into Tuesday to cover this system. By the middle of next week, ensembles agree on shifting heat ridge eastward more towards the Plains and Midwest, but there are differences in how aggressive this ridge builds into the local area. Some ensembles suggest ridge will build over the Ohio Valley, effectively capping off convective threat by the middle of next week, while others keep the center of the ridge more over the southern Plains. This would allow for the potential for periodic convective clusters along the edge of the heat ridge to affect the area. For now, will keep some small chance PoPs in the forecast for next Wednesday and Thursday to cover this possibility. && .AVIATION /Discussion for the 010900Z KIND TAF Update/... Issued at 428 AM EDT Fri Jul 1 2016 Scattered convection over east central Illinois seems to be diminishing a bit in intensity over the past hour. Convective potential around the KIND terminal doesn`t look particularly high early this morning, with the best potential around 011000Z-011400Z. Will hold onto CB`s in the vicinity of the KIND terminal in that time frame for now. Previous discussion follows. Challenge right now is if there will be showers/storms move across the area over the next six hours or so. HRRR is skimpy with the -TSRW generating isolated activity. This is in line with the storms that are on satellite currently in IL moving just south of east. Look like the best chance for precipitation across the region will be the 08Z-12Z time frame. Models also want to generate IFR/MVFR conditions towards morning, but RH fields clear pretty rapidly as the cold front moves southeast through the area by 12Z- 14Z. Looks like skies could clear out after the front goes through, but will hold on to some low scattered clouds during the morning. && .IND Watches/Warnings/Advisories...NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN SHORT TERM...RYAN LONG TERM....JAS AVIATION...DWM/JAS
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
622 PM CDT FRI JUL 1 2016 ...Update to aviation forecast discussion... .SHORT TERM...(This Evening through Saturday) Issued at 344 PM CDT FRI JUL 1 2016 This afternoon a deep mid-level trough was stretched across the eastern U.S. with surface high pressure situated west of the trough across the Northern and Central Plains. This west-northwesterly flow aloft combined with low/mid cloud cover supported cooler conditions this afternoon with highs topping out in the low/mid 80s. Drier conditions from the surface high were noted across northeast Kansas where dewpoint temperatures dropped into the 40s with dewpoints in the 50s to near 60 degrees elsewhere. With these drier conditions in place, the onset of precipitation will be slower than originally expected as it will take longer to overcome the drier air and for the atmospheric profile to become more deeply saturated. As a result, have lowered PoPs for eastern Kansas late afternoon into this evening. There actually is still model uncertainty with the eastward progression of precipitation tonight into Saturday morning as some models are showing the better lift holding off until overnight across north central to east central Kansas as the low- level jet begins to increase over the area. The larger-scale models still show showers and thunderstorms overspreading the entire forecast area overnight, while the early afternoon model runs of the HRRR and RAP suggest that precipitation may not even advance into northeast Kansas overnight. If this slower solution pans out, then PoPs are too high across eastern Kansas for overnight tonight. However, expect moderate to heavy rainfall rates overnight into Saturday morning with any precipitation that develops as an embedded shortwave lifts northeastward over the area. Model soundings show a deep saturation layer developing with PWAT values upwards of around 2 inches. As a result, rainfall amounts of 1 to 1.5 inches will be possible across portions of north central, central, and east central Kansas by Saturday morning. While instability will be limited through tonight, 0-6km bulk shear values may be upwards of 40-50kts across north central Kansas, so cannot rule out the potential for a few strong storms tonight with gusty winds and hail being the primary hazards. Morning showers and thunderstorms will lift to the northeast as the first embedded shortwave exits the area and a surface warm front and inverted surface trough lift into east central Kansas by early afternoon. Models show the inverted surface trough becoming more north-south oriented during the afternoon hours, and this boundary should provide sufficient lift to support additional widespread showers and storms across north central and far northeast Kansas by mid to late afternoon. Model soundings show a deep saturation layer in place with this second round of storms, with PWAT values rising into the 2 to 2.5 inch range so expect increasing rainfall rates over north central Kansas during the mid/late afternoon hours. If we are able to see some breaks in the cloud cover between the morning and afternoon rounds of precipitation, conditions may destabilize enough to increase the concerns for strong to severe storms as 40- 50kts of 0-6km shear should still be in place. With a few rounds of moderate to heavy rainfall possible, a Flash Flood Watch remains in effect beginning tonight across the entire outlook area. As for temperatures, with the warm front lifting into east central Kansas Saturday afternoon, a decent spread in afternoon temperatures is likely. There is still some uncertainty with where across east central Kansas this temperature gradient will be, but the current forecast has high temperatures ranging from near 70 degrees in far northeast Kansas to the mid/upper 80s across central and east central Kansas. .LONG TERM...(Saturday Night through Friday) Issued at 344 PM CDT FRI JUL 1 2016 The upper trough over the southwest US is forecast to slowly move east into the Central Plains on Saturday and then into the Missouri Valley Saturday night. The upper trough should be strong enough to produce a surface wave along the stalled frontal boundary across southern Kansas Saturday afternoon. The upper trough and associated surface wave moves through the area by Sunday morning. The 12z NAM was faster with the system compared to the 12z GFS/ECMWF. The slower movement appears to be associated with a piece of shortwave energy moving into southern plains Sunday. In all cases, there is a high probability of a heavy rainfall event over northeast Kansas Saturday night. Low-level warm advection over surface boundary, synoptic scale UVV which should have a very moist airmass in place by that point to work with with PWAT values around 2 inches. The convective resolving models (ARW and NMM)produce thunderstorms over the forecast area Saturday night. The 12z NAM/GFS/ECMWF all produce significant pcpn over the area, although their maximum amounts are north of the area closer to the apparent 850 mb warm front. This decreases overall confidence somewhat, but enough confidence remains for high pops and heavy rain over the forecast area. The lingering shortwave energy on Sunday supports keep pops in over the east. Will end the flash flood watch at 12z Sunday morning over the western counties which by then will have very low chances of heavy precipitation. Surface high pressure will be over eastern Kansas on Independence Day which should result in dry weather and below normal temperatures. The 12z GFS is more bullish on building the upper ridge into the Central Plains compared to the 12z ECMWF. The GFS certainly looks drier and hotter Tue-Fri next week. Will go with a compromise at this point with very warm temperatures returning with a chance of thunderstorms due to warm advection Tuesday night. Thunderstorm chances return late in the forecast as a weak boundary moves into the area. && .AVIATION...(For the 00Z TAFS through 00Z Saturday Evening) Issued at 621 PM CDT FRI JUL 1 2016 The main change from the previous TAF was pushing back the timing for TSRA into the terminals. Short term guidance suggests the main complex of storms will move into terminals between 09-10Z and remain until late morning. Have kept VFR ceilings for now with SCT MVFR cloud bases due to continuing uncertainty with how low ceilings will be. IFR ceilings with any storms are also not out of the question. After 17-18Z, have only kept VCTS as the main complex of storms is expected to move out of the area, although scattered convection is possible through the afternoon. && .TOP Watches/Warnings/Advisories... Flash Flood Watch through Sunday evening for KSZ024-026-038>040- 054>056-058-059. Flash Flood Watch through Sunday morning for KSZ008>012-020>023- 034>037. && $$ SHORT TERM...Hennecke LONG TERM...Johnson AVIATION...Heller
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
401 AM CDT THU JUN 30 2016 .SHORT TERM...(Today and Tonight) Issued at 355 AM CDT THU JUN 30 2016 Remnants of yet another overnight MCS were weakening and moving into north central KS at 330 AM while other widely scattered thunderstorms had been developing in far eastern KS mainly east of HWY 75. The north central KS activity should ease into parts of the local forecast area, but will probably remain west of a Belleville to Abilene line through sunrise. One question for the day will be if any remnants MCV from this system can maintain scattered thunderstorms as it drifts into the area this morning. There is also a secondary thunderstorm complex moving southeast on the boundary set up by this initial MCS, and while it will most likely point south of the local area will want to keep an eye on the evolution over the next few hours. Meanwhile the eastern KS activity, driven by weak isentropic ascent in an uncapped MU Parcel atmosphere, should persist for at least a few hours with a very gradual shift to the east and south as the weak LLJ veers and the focus shifts. None of this thunderstorm activity through sunrise is expected to be severe, but brief storm organization into stronger updrafts is not out of the question. Storms in these areas may persist beyond sunrise, but better chances for a few strong storms may focus this afternoon. Expect another warm day well into the 80s and similar to Wednesday although again somewhat dependent upon cloud cover. This will support moderate destabilization with 25 to 30 kts of 0-6 km shear. A cool front will push into the area from the north while surface low pressure will deepen in southeast Colorado with a surface trough extending into east central KS. Will see increasing convergence along this surface trough and the incoming front which will probably lead to scattered thunderstorm development by around mid day, mainly near/south of I-70. A few of these storms could become severe with damaging wind and marginally severe hail. They should also produce outflow which should help the front progress south of the forecast area by this evening. The zone north of this front should then become the focus for elevated thunderstorm development by late evening as a modest low level jet converges with elevated parcels having little to no inhibition. Expect one focus for storms to be basically along the southwest border of the coverage area from Minneapolis down through Burlington. Severe storms are unlikely with this activity given only modest instability, but the convective focus could be slow to move and areas of locally heavy rain will be possible. The relatively dry ground conditions suggest that flash flood guidance is unlikely to be met through tonight but will be something to keep an eye on. Regardless, this may be a precursory rain to set up flooding potential with the additional heavy rains at the end of the week. .LONG TERM...(Friday through Wednesday) Issued at 355 AM CDT THU JUN 30 2016 Overall confidence is increasing for periods of thunderstorms, heavy rainfall, and flooding for much of the area this weekend. Given the consistency of the models, favorable setup synoptically, and the impacts from the holiday weekend, have issued a Flash Flood Watch for the entire northeast Kansas area Friday evening through Sunday. Details to follow. Overnight convection may linger into Friday morning for north central areas, however with the waning low level jet believe there will be a break from precipitation for much of the cwa Friday afternoon before an organized mid level trough enters western Kansas Friday evening. All guidance continues to support showers and thunderstorms developing over central KS, gradually tracking east into northeast KS after midnight through the day Saturday. Have increased pops for this period in the 70-80% range. Forecast soundings highlight the heavy rainfall potential given the strong moisture flux into the area, rising PWAT values over 2 inches and cloud tops warming to over 13 kft. Could see more widespread convective precipitation redevelop Saturday afternoon and evening as MUCAPE values increase in excess of 2000 J/KG and bulk shear values are in the 35 to 40 kt range. A few of these storms may become severe with mainly hail and damaging wind gusts. Heaviest precipitation begins to slowly shift eastward on Sunday, affecting east central areas. The most concerning hazard for the weekend is the flooding potential across the entire area. Forecast QPF amounts have consistently ranged in the 2 to 4 inch range, although it is likely for some locations to receive up to 6 inches of rainfall by Sunday evening. It is too difficult to discern where these locations will be, however confidence is high enough for the widespread rainfall to cause flooding issues and have therefore issued a Flash Flood Watch in coordination with the Kansas City office. Temperatures over the weekend remain well below normal with highs in the lower 80s and lows in the lower 60s. This is still above the very cool guidance that models have not handled well this past week. Temporary, shortwave ridging builds over the western high plains, placing a temporary hold on widespread thunderstorms for the Fourth of July. Could still see a few thunderstorms in the evening, especially over central KS, but overall should remain dry with highs in the lower to middle 80 and overnight lows in the upper 60s. Weak troughing embedded within the westerly flow aloft will continue to bring scattered thunderstorms into the region Tuesday and Wednesday. Confidence is not high with the GFS and ECMWF still depicting varying solutions. Southerly flow and moisture return seems to be a better bet with highs back into the 90s and dewpoints in the 70s. && .AVIATION...(For the 06Z TAFS through 06Z Thursday Night) Issued at 1152 PM CDT WED JUN 29 2016 VFR conditions are expected through the period. Thunderstorms across Nebraska are expected to move to the southeast through 12Z. Confidence in timing at the terminals is low, and most short term models weaken the complex or keep it to the west of MHK. Will leave out of the tafs for now. Development of additional tsra is possible after 00Z Friday and may affect the MHK terminal after 03Z. Winds light and variable becoming light north to northeast after 18Z. && .TOP Watches/Warnings/Advisories... Flash Flood Watch from Friday evening through Sunday evening for KSZ008>012-020>024-026-034>040-054>056-058-059. && $$ SHORT TERM...Barjenbruch LONG TERM...Prieto AVIATION...53
Area Forecast Discussion National Weather Service Goodland KS 228 AM MDT THU JUN 30 2016 .UPDATE... Issued at 1122 PM MDT Wed Jun 29 2016 With the storm activity moving south of the area have cancelled the severe thunderstorm watch. North of the Tri-State Area a new round of storms will impact the area during the overnight hours. The storm activity may last into the early morning hours if the storms in the Nebraska Panhandle make it this far south. Main threat with the storms overnight will be large hail although severe wind gusts cannot be ruled out. && .SHORT TERM...(This evening through Thursday) Issued at 157 PM MDT Wed Jun 29 2016 As of 3 PM CDT/2 PM MDT, skies across the Tri-State Region are mostly clear. A few cumulus clouds have recently developed over east Colorado and extreme northwest Kansas. Temperatures are in the mid to upper 80s for most locations. Winds are generally less than 10 mph for most locations. However, south winds are beginning to pick up to 10-15 mph, gusting to 20 mph. At the surface, an area of low pressure was located along the Colorado Front Range. A weak front/remnant outflow boundary is located across eastern Colorado. Aloft, a shortwave trough is moving across Colorado. Thunderstorms have developed over the Rockies ahead of this trough. For this evening and tonight, am expecting another round of strong to severe thunderstorms to move across the region. High resolution guidance, while varying somewhat amongst each piece of guidance, suggest that storms develop this afternoon over eastern Colorado and Wyoming. Then, as the evening progresses, storms should coalesce into another complex or two, spreading southeast across the Tri- State Region. Storms should exit the region after midnight. Overall, am not anticipating quite the storm intensity as last night as the atmosphere has been worked over some. Current mesoanalysis does indicate SBCAPE up to 2500 J/KG in some locations but a cap persists. When the cap breaks, strong/severe thunderstorms should quickly develop. In addition, strong shear remains (0-6 KM Bulk Shear is 40-50 kts). Therefore, anticipating the primary threat with these storms to be damaging winds once again. Any initial development will be capable of large hail, very large possible. Further, recent heavy rains have saturated the soils for some locations. These locations, if they receive additional heavy rain from thunderstorms, would be prone to flash flooding tonight. Was not confident enough to issue a flash flood watch at this time due to some disagreement in guidance with regards to the movement of this complex. For tomorrow, a cold front should push south across the region. As a result of the front and likely extensive cloud cover, cooler temperatures are forecast. Instability parameters remain favorable for some strong/severe thunderstorms, particularly later in the afternoon hours. Thinking the highest chances for thunderstorms (in the afternoon) will be along/west of a line from Benkelman, Nebraska to Tribune, Kansas. Large hail and damaging winds will be possible. Winds aloft should weaken so slower storm movement appears likely. In addition, precipitable water content increases. Therefore, heavy rain and flash flooding may become an issue. .LONG TERM...(Sunday through Wednesday) Issued at 227 AM MDT Thu Jun 30 2016 H5 trough axis moves east on Sunday and pulls the better rain chances with it. PoPs remain in the eastern portions of the CWA through the afternoon with an isolated thunderstorm or two possible elsewhere. Another weak shortwave and associated axis of instability will move across the region Monday with slgt chc to chc PoPs mainly during the afternoon to early evening. Tuesday we will see good moisture transport at the 850mb level out of the south which will combine with ample instability during the afternoon and early evening to trigger thunderstorm development in the presence of weak forcing. For Wednesday and Thursday, weak shortwave ridge builds and moves east. This will serve to cut off the moisture flow at the 850mb to 700mb level and dry things out across the CWA. There will be instability in the region; however, with little forcing there will be little to no chance of thunderstorm development. The global models are both highlighting the beginnings of a monsoonal type trough development in the southwest late in the extended period which will increase the PoPs once more but will need to see better consistency before committing to higher rain chances. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1122 PM MDT Wed Jun 29 2016 VFR conditions expected for the TAFs. Main issue in the near term will be the line of storms that recently formed north of KMCK. This line of storms will impact the site around 630z and may linger over the site for an hour. Am expecting breezy winds and moderate to possibly heavy rainfall with some hail. During the late afternoon storm activity approaching from the northwest may impact the TAF sites, particularly KGLD. && .GLD Watches/Warnings/Advisories... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...JTL SHORT TERM...RRH LONG TERM...TL AVIATION...JTL
Area Forecast Discussion National Weather Service Dodge City KS 326 AM CDT THU JUN 30 2016 ...Updated long term section... .SHORT TERM...(Today and tonight) Issued at 239 AM CDT Thu Jun 30 2016 A slight chance of thunderstorms will exist this morning across central Kansas as the remnants of a MCS moves south out of Nebraska and into Kansas. Otherwise, expect decreasing cloudiness this morning becoming partly cloudy this afternoon. Thunderstorm chances increase once again late afternoon into the overnight period as an upper level shortwave moves up and over an upper level ridge located over the southern Rockies. Skies will become mostly cloudy tomorrow night as the thunderstorm activity rolls through the area. At the surface, an area of low pressure will be located across southeastern Colorado today with a stationary front bisecting Kansas. This will lead to south to southeasterly winds across the southern half of the CWA shifting to more of an easterly direction across the northern half of the CWA. Winds shift to more of an easterly direction tonight as the frontal boundary gets pushed to the south. As for temperatures, highs today look to reach into the upper 80s to around 90 degrees with lows tonight ranging from the lower 60s across eastern Colorado to upper 60s across south central Kansas. .LONG TERM...(Friday through Wednesday) Issued at 325 AM CDT Thu Jun 30 2016 Thunderstorm chances continue into the weekend as a series of disturbances move through the area. Flow aloft will generally be from the northwest initially becoming more zonal this weekend. Ample moisture in the low to mid levels of the atmosphere will bring partly to mostly cloudy skies to western Kansas through this weekend. Towards the surface, an area of low pressure will continue to be confined southwest of the area with a frontal boundary extending eastward along the KS/OK border. This will lead to east to southeasterly direction Friday shifting to more of a northeasterly direction this weekend. A ridge of high pressure builds into the area during the first part of next week. Thunderstorms will be possible during the afternoon and evening hours, however, they should be more isolated than what we are expecting into this weekend. As for temperatures, highs will generally be in the 80s into this weekend reaching into the 90s next week. Lows look to dip into the 60s. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1151 PM CDT Wed Jun 29 2016 Scattered showers are currently moving through far western Kansas but are expected to stay west of the GCK terminal. I did place VCTS in the TAFs to account for the close proximity. Otherwise, VFR conditions will prevail with increasing mid level clouds. Winds will generally be from the south to southeast at less than 10 knots. A better chance of thunderstorms are possible tomorrow night, especially around the HYS terminal. && .PRELIMINARY POINT TEMPS/POPS... DDC 89 65 84 65 / 40 60 50 50 GCK 88 65 83 64 / 40 50 50 50 EHA 90 63 87 66 / 40 50 40 40 LBL 91 65 89 68 / 40 50 40 40 HYS 86 64 79 63 / 40 60 60 60 P28 91 68 87 68 / 40 70 50 50 && .DDC Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Hovorka_42 LONG TERM...Hovorka_42 AVIATION...Hovorka_42
Area Forecast Discussion National Weather Service Wichita KS 243 AM CDT THU JUN 30 2016 .SYNOPSIS... Issued at 241 AM CDT Thu Jun 30 2016 In the upper levels, currently have a deep trough situated over eastern Canada into the northeast CONUS with some shortwave energy diving southeast across southern Manitoba/western Ontario. At the surface, strong cold front stretches from northern MN through southern ND. Meanwhile, high pressure is centered over the Ohio/Tennessee Valley. && .SHORT TERM...(Today through Saturday night) Issued at 241 AM CDT Thu Jun 30 2016 Just like the last few nights, we are watching an mcs push south across southern Nebraska/northern KS with the big question how far south and east it will make it this morning. At this point it looks like at least central KS will get in on some precip this morning but still not sold it will make it down to south central KS based on how things have paned out the last few days. Outside of the activity this morning, confidence is low that we`ll see any additional development today, especially since the front doesn`t look like it will make it as far south as models projected yesterday. So one of the more significant changes to the going forecast was to knock down pops quite a bit for today. The better MCS activity will arrive tonight as the upper pattern starts to flatten out, which will allow the dirty moonsonal flow to spill into the area. Low levels will respond to this with an overnight low level jet which will also increase moisture transport in the 850-700mb layer. Confidence is high that storms will either develop out over the high Plains late this afternoon and move into the forecast area tonight or storms will develop on the low level jet this evening over west-central KS. Regardless of which scenario pans out, much of the forecast area should see rain tonight and with precipitable water values around 2 inches, any strong shower or storm will produce very high rainfall rates. The overnight activity should linger Fri morning, especially over the northeast portion of the forecast area. The same basic setup will be in play Fri night with the better moisture transport and low level jet convergence lifting slightly north. This would place the better heavy rain potential Fri night into Sat morning over central KS. There is still decent agreement between the ECMWF and GFS in a more robust upper wave sliding across the forecast area Sat through Sun. This will produce another round of widespread showers and storms with heavy rainfall and flooding still looking like the main threat as we maintain a very tropical airmass. .LONG TERM...(Sunday night through Wednesday) Issued at 241 AM CDT Thu Jun 30 2016 By Sun night the upper impulse will be situated over far eastern KS/western MO with the bulk of the rain chances out of the forecast area by Mon morning, with most of the area remaining dry for the 4th. Will run with some small storm chances Mon night through Tue night but confidence in this panning out is very low as there isn`t a significant upper wave or front to key on. && .AVIATION...(For the 00Z TAFS through 00Z Thursday evening) Issued at 942 PM CDT Wed Jun 29 2016 Thunderstorms will continue to move eastward from western Kansas and southward across Nebraska tonight, however the activity is expected to decrease as it approaches central Kansas late tonight. Winds will remain light during the day on Thursday and back to the east/southeast direction later in the afternoon. More numerous thunderstorms will develop over western Kansas Thursday afternoon/evening and spread into central Kansas. && .PRELIMINARY POINT TEMPS/POPS... Wichita-KICT 71 90 69 85 / 10 30 60 50 Hutchinson 70 89 68 83 / 20 30 60 50 Newton 69 89 68 82 / 20 30 60 50 ElDorado 70 90 69 83 / 10 30 60 50 Winfield-KWLD 71 91 70 85 / 10 40 60 50 Russell 68 88 66 79 / 30 30 70 50 Great Bend 69 88 66 81 / 20 30 70 50 Salina 69 88 67 80 / 20 20 50 50 McPherson 69 89 67 82 / 20 30 50 50 Coffeyville 70 91 71 84 / 20 30 60 60 Chanute 69 89 70 83 / 20 30 60 60 Iola 69 88 69 82 / 20 30 60 60 Parsons-KPPF 69 90 70 84 / 20 30 60 60 && .ICT Watches/Warnings/Advisories... None. && $$ SHORT TERM...RBL LONG TERM...RBL AVIATION...CDJ
Area Forecast Discussion National Weather Service Dodge City KS 239 AM CDT THU JUN 30 2016 ...Updated short term section... .SHORT TERM...(Today and tonight) Issued at 239 AM CDT Thu Jun 30 2016 A slight chance of thunderstorms will exist this morning across central Kansas as the remnants of a MCS moves south out of Nebraska and into Kansas. Otherwise, expect decreasing cloudiness this morning becoming partly cloudy this afternoon. Thunderstorm chances increase once again late afternoon into the overnight period as an upper level shortwave moves up and over an upper level ridge located over the southern Rockies. Skies will become mostly cloudy tomorrow night as the thunderstorm activity rolls through the area. At the surface, an area of low pressure will be located across southeastern Colorado today with a stationary front bisecting Kansas. This will lead to south to southeasterly winds across the southern half of the CWA shifting to more of an easterly direction across the northern half of the CWA. Winds shift to more of an easterly direction tonight as the frontal boundary gets pushed to the south. As for temperatures, highs today look to reach into the upper 80s to around 90 degrees with lows tonight ranging from the lower 60s across eastern Colorado to upper 60s across south central Kansas. .LONG TERM...(Thursday night through Wednesday) Issued at 305 PM CDT Wed Jun 29 2016 For the period of Thursday night into next Wednesday, an ongoing convective complex of storms may be moving across parts of western Kansas Thursday night with aggravated northwest flow aloft. For Friday northwest flow aloft begins to transition to more zonal flow with more shortwaves forecast into Sunday across the Western High Plains. Will keep fairly high chances going for rainfall, and areas of heavy rainfall still look good. After Sunday, rainfall chances decrease as the main upper jet and any shortwaves move north. Highs will be cooler and in the 80s into Sunday, but then warm back into the 90s by mid week next week. Lows will be mainly in the 60s then warm to around 70 after Monday. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1151 PM CDT Wed Jun 29 2016 Scattered showers are currently moving through far western Kansas but are expected to stay west of the GCK terminal. I did place VCTS in the TAFs to account for the close proximity. Otherwise, VFR conditions will prevail with increasing mid level clouds. Winds will generally be from the south to southeast at less than 10 knots. A better chance of thunderstorms are possible tomorrow night, especially around the HYS terminal. && .PRELIMINARY POINT TEMPS/POPS... DDC 89 65 84 65 / 40 60 50 50 GCK 88 65 83 64 / 40 50 50 50 EHA 90 63 87 66 / 40 50 40 40 LBL 91 65 89 68 / 40 50 40 40 HYS 86 64 79 63 / 40 60 60 60 P28 91 68 87 68 / 40 70 50 50 && .DDC Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Hovorka_42 LONG TERM...Kruse AVIATION...Hovorka_42
Area Forecast Discussion National Weather Service Dodge City KS 239 AM CDT THU JUN 30 2016 ...Updated short term section... .SHORT TERM...(Today and tonight) Issued at 239 AM CDT Thu Jun 30 2016 A slight chance of thunderstorms will exist this morning across central Kansas as the remnants of a MCS moves south out of Nebraska and into Kansas. Otherwise, expect decreasing cloudiness this morning becoming partly cloudy this afternoon. Thunderstorm chances increase once again late afternoon into the overnight period as an upper level shortwave moves up and over an upper level ridge located over the southern Rockies. Skies will become mostly cloudy tomorrow night as the thunderstorm activity rolls through the area. At the surface, an area of low pressure will be located across southeastern Colorado today with a stationary front bisecting Kansas. This will lead to south to southeasterly winds across the southern half of the CWA shifting to more of an easterly direction across the northern half of the CWA. Winds shift to more of an easterly direction tonight as the frontal boundary gets pushed to the south. As for temperatures, highs today look to reach into the upper 80s to around 90 degrees with lows tonight ranging from the lower 60s across eastern Colorado to upper 60s across south central Kansas. .LONG TERM...(Thursday night through Wednesday) Issued at 305 PM CDT Wed Jun 29 2016 For the period of Thursday night into next Wednesday, an ongoing convective complex of storms may be moving across parts of western Kansas Thursday night with aggravated northwest flow aloft. For Friday northwest flow aloft begins to transition to more zonal flow with more shortwaves forecast into Sunday across the Western High Plains. Will keep fairly high chances going for rainfall, and areas of heavy rainfall still look good. After Sunday, rainfall chances decrease as the main upper jet and any shortwaves move north. Highs will be cooler and in the 80s into Sunday, but then warm back into the 90s by mid week next week. Lows will be mainly in the 60s then warm to around 70 after Monday. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1151 PM CDT Wed Jun 29 2016 Scattered showers are currently moving through far western Kansas but are expected to stay west of the GCK terminal. I did place VCTS in the TAFs to account for the close proximity. Otherwise, VFR conditions will prevail with increasing mid level clouds. Winds will generally be from the south to southeast at less than 10 knots. A better chance of thunderstorms are possible tomorrow night, especially around the HYS terminal. && .PRELIMINARY POINT TEMPS/POPS... DDC 89 65 84 65 / 40 60 50 50 GCK 88 65 83 64 / 40 50 50 50 EHA 90 63 87 66 / 40 50 40 40 LBL 91 65 89 68 / 40 50 40 40 HYS 86 64 79 63 / 40 60 60 60 P28 91 68 87 68 / 40 70 50 50 && .DDC Watches/Warnings/Advisories... NONE. && $$ SHORT TERM...Hovorka_42 LONG TERM...Kruse AVIATION...Hovorka_42
Area Forecast Discussion National Weather Service Goodland KS 1127 PM MDT WED JUN 29 2016 .UPDATE... Issued at 1122 PM MDT Wed Jun 29 2016 With the storm activity moving south of the area have cancelled the severe thunderstorm watch. North of the Tri-State Area a new round of storms will impact the area during the overnight hours. The storm activity may last into the early morning hours if the storms in the Nebraska Panhandle make it this far south. Main threat with the storms overnight will be large hail although severe wind gusts cannot be ruled out. && .SHORT TERM...(This evening through Thursday) Issued at 157 PM MDT Wed Jun 29 2016 As of 3 PM CDT/2 PM MDT, skies across the Tri-State Region are mostly clear. A few cumulus clouds have recently developed over east Colorado and extreme northwest Kansas. Temperatures are in the mid to upper 80s for most locations. Winds are generally less than 10 mph for most locations. However, south winds are beginning to pick up to 10-15 mph, gusting to 20 mph. At the surface, an area of low pressure was located along the Colorado Front Range. A weak front/remnant outflow boundary is located across eastern Colorado. Aloft, a shortwave trough is moving across Colorado. Thunderstorms have developed over the Rockies ahead of this trough. For this evening and tonight, am expecting another round of strong to severe thunderstorms to move across the region. High resolution guidance, while varying somewhat amongst each piece of guidance, suggest that storms develop this afternoon over eastern Colorado and Wyoming. Then, as the evening progresses, storms should coalesce into another complex or two, spreading southeast across the Tri- State Region. Storms should exit the region after midnight. Overall, am not anticipating quite the storm intensity as last night as the atmosphere has been worked over some. Current mesoanalysis does indicate SBCAPE up to 2500 J/KG in some locations but a cap persists. When the cap breaks, strong/severe thunderstorms should quickly develop. In addition, strong shear remains (0-6 KM Bulk Shear is 40-50 kts). Therefore, anticipating the primary threat with these storms to be damaging winds once again. Any initial development will be capable of large hail, very large possible. Further, recent heavy rains have saturated the soils for some locations. These locations, if they receive additional heavy rain from thunderstorms, would be prone to flash flooding tonight. Was not confident enough to issue a flash flood watch at this time due to some disagreement in guidance with regards to the movement of this complex. For tomorrow, a cold front should push south across the region. As a result of the front and likely extensive cloud cover, cooler temperatures are forecast. Instability parameters remain favorable for some strong/severe thunderstorms, particularly later in the afternoon hours. Thinking the highest chances for thunderstorms (in the afternoon) will be along/west of a line from Benkelman, Nebraska to Tribune, Kansas. Large hail and damaging winds will be possible. Winds aloft should weaken so slower storm movement appears likely. In addition, precipitable water content increases. Therefore, heavy rain and flash flooding may become an issue. .LONG TERM...(Thursday night through Wednesday) Issued at 303 PM MDT Wed Jun 29 2016 Forecast issues will continue to be the threat of thunderstorms, severe weather, and heavy rainfall...especially into the beginning of the weekend. Satellite showing showing an amplified pattern from the eastern Pacific into North America. Upper ridge is currently near the four corners region with subtropical working its way around western side of this ridge. At mid levels...The Canadian/Gfs/Ecmwf were doing the best with the Nam and Sref starting out the worst. The Canadian and gfs did the best on the low level thermal field. Thursday night...numerous shortwave troughs shown. Models appear to not show a lot of lift until the later half of the night when a stronger and negatively tilted shortwave trough approaches the area. Initially most of the precipitation looks to be in the southwest half with a gradual increase in the last half of the night. Some severe possible with probably a greater threat for heavy rainfall due to above normal Pwats. Friday/Friday night...Negatively tilted mid/upper level trough will move slowly toward the area during the day with two different shortwave troughs moving through. One will be early and is the one that begins to affect the area late Thursday night and will move northeast through the day. A second shortwave trough moves in from the southwest in the afternoon. The lift is actually the strongest during the night, with the highest pops of this period, as the entire upper trough moves in closer to the area. Right rear quadrant of jet moves across during the afternoon and evening. There may be a brief break somewhere in their during the day however that will be hard to time. Will have high chance to likely pops in during the day and likely during the night. It may be more embedded thunderstorms in the showers in the morning with more instability and thunderstorms present in the afternoon and night. With a cooler air mass and lots of cloud cover, instability will not be very high. Could not rule out an isolated severe storm but do not expect widespread severe weather. The main threat will be heavy rainfall. Pwats remain near or a little above 1.5 through the entire period which is near 2 standard deviations above normal. Storm motions increase through the day but heavy rainfall still appears to be another good bet. Looks like temperatures will have a hard time climbing this day with cloud cover, ongoing rainfall, and low level upslope. Saturday...the day starts with a complex mid level trough over the forecast area. It appears it slowly moves across the area and then stalls/deepens on top of our area as another shortwave trough comes down the west side of the trough. The models appear to start to try to close off a circulation at 700 mb. Also it appears that a front is near to just southeast of the area. Pwats actually increase into the 1.5 to 2 inch range. It appears that heavy rainfall will be the main threat. However, with a mid level center parked over the area, it could set the stage for low top supercells and landspouts. Saturday night through Wednesday...Continued active period looks to continue. In general the models are the same with the mid level ridge getting suppressed much further south and weak troughing along the west coast of North America. Numerous shortwave troughs are embedded within this flow as one would expect the models are having trouble handling them and do differ on the details of speed and amplitude. Models/Wpc manual progs show synoptic boundaries in and near the area through the whole period. However, given the flow pattern and shortwave troughs aloft, models will probably handle these well at this distance. And that is not even accounting for the mesoscale affects of repeated bouts of thunderstorms. The extended blend provided higher pops on saturday night then steadily decreases pops and has only spotty slight chance to low chance pops for the rest of the period. This looks reasonable considering the model differences and uncertainties in such a complex pattern. However, definitely will be possible for pops to end up being higher. Warmer trend looks to be store, and also appears to be reasonable. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1122 PM MDT Wed Jun 29 2016 VFR conditions expected for the TAFs. Main issue in the near term will be the line of storms that recently formed north of KMCK. This line of storms will impact the site around 630z and may linger over the site for an hour. Am expecting breezy winds and moderate to possibly heavy rainfall with some hail. During the late afternoon storm activity approaching from the northwest may impact the TAF sites, particularly KGLD. && .GLD Watches/Warnings/Advisories... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...JTL SHORT TERM...RRH LONG TERM...BULLER AVIATION...JTL
Area Forecast Discussion National Weather Service Dodge City KS 1156 PM CDT WED JUN 29 2016 ...Updated aviation section... .UPDATE... Issued at 814 PM CDT Wed Jun 29 2016 Based on radar trends in eastern Colorado and the latest HRRR solutions, increased thunderstorm coverage across the western zones toward midnight. HRRR has a good handle on storm coverage at present, and suggests likely coverage mainly west of Garden City. Per coordination with SPC, strongest risk for damaging winds will be across Hamilton/Kearny county vicinity toward midnight. && .SHORT TERM...(This evening through Thursday) Issued at 251 PM CDT Wed Jun 29 2016 A wind shift line has moved to between Garden City and Dodge City this afternoon with some cumulus just south of Dodge City, and another area of more enhanced cumulus in parts of Barber County. Forecast soundings are unstable with only a weak cap over the Dodge City area and 2000 to 3000 J/kg forecast CAPE. There could be an isolated thunderstorm near the wind shift line and then a slightly better chance in the Barber County area. If any storm develops it could go briefly severe with quarter hail and a strong wind gust. Then later tonight, models show the best chances for rainfall are mainly north of Dodge City, however with this current northwest flow pattern, any storms that develop in eastern Colorado and Nebraska could dive southward into much of the area. Will keep 30 to 50 percent chance going. Severe storms do not look likely with the main threat of strong outflow winds, small hail, and heavy rainfall with any storm complex that can develop. It may also be more difficult for storms to form in far western Kansas this evening and overnight as 700 mb temps are fairly warm around 15C. Lows tonight will range from the mid to upper 60s with light southeast winds. For Thursday, a stronger shortwave in northwest flow aloft is forecast for the afternoon and evening with an attendant cold front moving across western Kansas. Will keep fairly high chances for rainfall going, again with a potential of heavy rainfall. Could also have a chance of strong to severe storms with stronger wind shear forecast. .LONG TERM...(Thursday night through Wednesday) Issued at 305 PM CDT Wed Jun 29 2016 For the period of Thursday night into next Wednesday, an ongoing convective complex of storms may be moving across parts of western Kansas Thursday night with aggravated northwest flow aloft. For Friday northwest flow aloft begins to transition to more zonal flow with more shortwaves forecast into Sunday across the Western High Plains. Will keep fairly high chances going for rainfall, and areas of heavy rainfall still look good. After Sunday, rainfall chances decrease as the main upper jet and any shortwaves move north. Highs will be cooler and in the 80s into Sunday, but then warm back into the 90s by mid week next week. Lows will be mainly in the 60s then warm to around 70 after Monday. && .AVIATION...(For the 06Z TAFS through 06Z Thursday night) Issued at 1151 PM CDT Wed Jun 29 2016 Scattered showers are currently moving through far western Kansas but are expected to stay west of the GCK terminal. I did place VCTS in the TAFs to account for the close proximity. Otherwise, VFR conditions will prevail with increasing mid level clouds. Winds will generally be from the south to southeast at less than 10 knots. A better chance of thunderstorms are possible tomorrow night, especially around the HYS terminal. && .PRELIMINARY POINT TEMPS/POPS... DDC 68 89 65 82 / 30 50 60 50 GCK 66 88 65 83 / 70 50 60 50 EHA 66 91 64 86 / 30 50 60 50 LBL 67 92 66 87 / 40 50 60 50 HYS 67 85 64 81 / 40 40 40 50 P28 70 91 68 84 / 30 50 60 50 && .DDC Watches/Warnings/Advisories... NONE. && $$ UPDATE...Turner SHORT TERM...Kruse LONG TERM...Kruse AVIATION...Hovorka_42 Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 441 PM AKDT FRI JUL 1 2016 .ANALYSIS AND UPPER LEVELS... The upper level low remains over the Gulf of Alaska, but is beginning to show signs of moving east. The strong short-wave system on the northwest side of the low that provided last nights rainfall to south central Alaska is now in southwest Alaska. There is an upper level low over the southwest Bering Sea as well as the western and central Aleutians. This low has stalled and is continuing to weaken. A weather front associated with this low stretches from about Nikolski northwestward across the Bering Sea. A ridge of high pressure separates these two low, with the "col" over the far eastern Bering. && .MODEL DISCUSSION... The numerical models are in reasonable agreement on the over-all pattern. There continue to be some differences in the timing, location, and strength of various short-waves surrounding the Gulf low. There are also some minor differences in the handling of precipitation, especially in regards to convection. Therefore the forecast confidence is slightly below normal. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2...Sat and Sun)... Afternoon mountain showers and diurnal sea breezes will be the story for the weekend. The easterly wave that brought a third to an inch and half of rain across Southcentral has cleared through most of the area. The Alaska Range has slowed its westward progress keeping some rain falling over Kachemak Bay. It will pivot through this corridor on Sat bringing rain to parts of Kodiak Island later tonight through the Sat morning hours. Meanwhile...the rest of the area will remain in very light flow with generally moist and unstable conditions. With all the recent rainfall...many places could see some patchy fog or low stratus develop overnight. But this should dissipate relatively quickly on Saturday as some sun breaks through. Showers should develop along the mountains in the afternoon, but with weak steering flow, we don`t expect many of them to make it into valleys. The best instability remains farther north over the Alaska Range and parts of the Talkeetna Mountains, so can`t rule out an isolated thunderstorm developing on those higher peaks. Sun looks very similar to Sat with minimal change to the pattern. The leftover band of rain near Kodiak should move off into the Gulf making for drying conditions there. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... The Gulf low that has been relatively stationary the last couple of days will finally push off to the east tonight. This will change the easterly flow over the area to be more northerly which will help to diminish showers over the area. The majority of the rain remaining by the beginning of next week will be in the more eastern parts of Southwest Alaska like the Alaska and Aleutian Ranges. Even though the main upper level low is departing there are still more shortwaves moving through the area with the strongest one coming through this evening. It will track south from the Kuskokwim Valley towards Bristol Bay and will help to initiate thunderstorms in the area. There will also be enough instability over the Kuskokwim Valley for possible afternoon thunderstorms Saturday and Sunday. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... The broad area of low pressure over the Western Aleutians will track slowly east over the weekend. It looks to bring light rain to the Aleutians with some making it to the Pribilof Islands on Saturday. By the beginning of next week the broad upper level low will be absorbed into a broad trough extending across the Bering from the north. This trough will keep light rain over the Bering and Aleutians. && .LONG TERM FORECAST (Days 3 through 7)... The upper level pattern will begin to shift by the end of this weekend to a more stable pattern, as the upper low shifts further east and weak high pressure aloft builds in from the west. Thus, with everything being weak, any precipitation that develops Sunday over southern mainland Alaska will be mostly scattered and weak. The persistence of a mid-level unstable layer over much of the area will result in some diurnal showers mainly along the mountains. For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...BL SOUTHCENTRAL ALASKA...MO SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK LONG TERM...TP
  [top] Southeast Alaska Forecast Discussion National Weather Service Juneau AK 324 PM AKDT FRI JUL 1 2016 .SHORT TERM...A low just west of Sitka this afternoon continues to track north along the outer coast. Visible and WV satellite imagery is clearly depicting the circulation, but it is not nearly as evident in IR imagery. Radar has been showing banding in the returns, but the total system is slightly stronger than originally expected and had produced 30 kts of wind in Clarence Strait earlier today. Morning model runs still showing some divergence on the low center. With the system so close to the outer coast, minor differences in location, track, and intensity can have significant impacts in the forecast. That said, opted for the NAM for updates to pressure and winds today. Resulting changes primarily affect the winds over the eastern gulf and coastal locations north of Cape Decision. On the inside, result was to increase winds speeds a bit, so the afternoon forecast features small craft advisories for several of the inner channels. Clarence Strait is expected to continue at high end small craft intensity through the evening before relaxing. A low approaching the Dixon Entrance from the southwest tomorrow will produce another round of small craft winds out of the east tomorrow afternoon, but these winds will be mostly over southern areas near the Dixon Entrance. Small craft southerlies will get into the ocean entrances of Chatham Strait and Sumner Strait early this evening but should diminish to 15 kts or so by tomorrow morning. Also expect small craft winds out of the east over eastern portions of Sumner and southeasterlies to 25 kts along Frederick Sound south of Cape Fanshaw. Later tonight, max winds on the inside will shift north to include Stephens passage north of Taku inlet, the northern portions of Chatham Strait, and much of Icy Strait. Finally, easterly Small Craft winds to 30 kts from late this evening through tomorrow afternoon are forecast for Cross Sound. Small craft winds on the outside will progress from south to north as well, ending late morning as the low weakens and fills vicinity of Cape Fairweather. POP forecast from last night still looks good, so no changes there. Did update QPF using a blend of Canadian REG and NAMDNG. Overall forecast confidence is average to below average due to uncertainties in how inner channel winds will respond to the low off the coast. .LONG TERM...The low passing through Dixon Entrance Saturday night will keep showers largely confined to the southern panhandle. An upper level low shifts south Saturday night then looks to settle over central BC Sunday. This will also help to clear away showers initially over the north, but then once its in Canada may cause clouds and some showers to move in from the east. For this reason chance/slight chance of showers remain in the forecast over the weekend. Weak ridging will develop over the gulf starting Monday, or a better way to describe it, zonal onshore flow. This leads to a chance of rain in the forecast, or at least a bit more cloud cover. There are some indications that a marine layer could develop over the gulf under the ridge, this will be monitored over the next couple days. If an inversion develops or there is a low cloud deck that would be of concern for Monday night activities along the outer coast. Adjusted temps up slightly through the extended forecast as both base models and bias corrected models were warmer. Thinking that sunny breaks in the clouds will allow for more seasonable highs in the mid 60s. Used an ensemble approach for updates today. Model agreement on pressure was good through the mid range then diverged day 6, used more WPC guidance for later periods. Model differences on the POP forecast were still fairly high over the holiday, so still lower confidence in that part of the forecast. && .HYDROLOGY...Early afternoon indications are that Suicide Basin may have emptied out. The lake, however, will continue to rise through the evening, with a forecast crest of at or near 12 feet later tonight. See the flood warning issued by NWS Juneau for details and be careful and vigilant around flood waters. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ021-022-031>036-041>043. && $$ Fritsch/Ferrin Visit us at http://www.weather.gov/Juneau
Southeast Alaska Forecast Discussion National Weather Service Juneau AK 324 PM AKDT FRI JUL 1 2016 .SHORT TERM...A low just west of Sitka this afternoon continues to track north along the outer coast. Visible and WV satellite imagery is clearly depicting the circulation, but it is not nearly as evident in IR imagery. Radar has been showing banding in the returns, but the total system is slightly stronger than originally expected and had produced 30 kts of wind in Clarence Strait earlier today. Morning model runs still showing some divergence on the low center. With the system so close to the outer coast, minor differences in location, track, and intensity can have significant impacts in the forecast. That said, opted for the NAM for updates to pressure and winds today. Resulting changes primarily affect the winds over the eastern gulf and coastal locations north of Cape Decision. On the inside, result was to increase winds speeds a bit, so the afternoon forecast features small craft advisories for several of the inner channels. Clarence Strait is expected to continue at high end small craft intensity through the evening before relaxing. A low approaching the Dixon Entrance from the southwest tomorrow will produce another round of small craft winds out of the east tomorrow afternoon, but these winds will be mostly over southern areas near the Dixon Entrance. Small craft southerlies will get into the ocean entrances of Chatham Strait and Sumner Strait early this evening but should diminish to 15 kts or so by tomorrow morning. Also expect small craft winds out of the east over eastern portions of Sumner and southeasterlies to 25 kts along Frederick Sound south of Cape Fanshaw. Later tonight, max winds on the inside will shift north to include Stephens passage north of Taku inlet, the northern portions of Chatham Strait, and much of Icy Strait. Finally, easterly Small Craft winds to 30 kts from late this evening through tomorrow afternoon are forecast for Cross Sound. Small craft winds on the outside will progress from south to north as well, ending late morning as the low weakens and fills vicinity of Cape Fairweather. POP forecast from last night still looks good, so no changes there. Did update QPF using a blend of Canadian REG and NAMDNG. Overall forecast confidence is average to below average due to uncertainties in how inner channel winds will respond to the low off the coast. .LONG TERM...The low passing through Dixon Entrance Saturday night will keep showers largely confined to the southern panhandle. An upper level low shifts south Saturday night then looks to settle over central BC Sunday. This will also help to clear away showers initially over the north, but then once its in Canada may cause clouds and some showers to move in from the east. For this reason chance/slight chance of showers remain in the forecast over the weekend. Weak ridging will develop over the gulf starting Monday, or a better way to describe it, zonal onshore flow. This leads to a chance of rain in the forecast, or at least a bit more cloud cover. There are some indications that a marine layer could develop over the gulf under the ridge, this will be monitored over the next couple days. If an inversion develops or there is a low cloud deck that would be of concern for Monday night activities along the outer coast. Adjusted temps up slightly through the extended forecast as both base models and bias corrected models were warmer. Thinking that sunny breaks in the clouds will allow for more seasonable highs in the mid 60s. Used an ensemble approach for updates today. Model agreement on pressure was good through the mid range then diverged day 6, used more WPC guidance for later periods. Model differences on the POP forecast were still fairly high over the holiday, so still lower confidence in that part of the forecast. && .HYDROLOGY...Early afternoon indications are that Suicide Basin may have emptied out. The lake, however, will continue to rise through the evening, with a forecast crest of at or near 12 feet later tonight. See the flood warning issued by NWS Juneau for details and be careful and vigilant around flood waters. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ021-022-031>036-041>043. && $$ Fritsch/Ferrin Visit us at http://www.weather.gov/Juneau
  [top] Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 303 PM AKDT FRI JUL 1 2016 .SYNOPSIS... Aloft... A ridge stretching east to west across northern Alaska will persist through the weekend then retreat east in NW Canada next week as a trough develops over the Bering Sea. A low aloft in the Gulf of Alaska will move over SE Alaska Sat and then move slowly east. A series of short wave troughs rotating around this low will move west across Interior Alaska bringing bands of showers and isolated to scattered thunderstorms to the eastern and southern Interior through the weekend. A strong short wave that now lies from Denali to Livengood to Old Crow will move to McGrath to Tanana to Arctic Village by 4am Sat...and then weaken in place through Sun. There is a wide band of showers NW of this trough that becomes scattered north of the Yukon River. This dropped .10 to .25 inch of rain over the eastern Interior south of Circle with up to .50 inch in the hills north of Fox and east of Delta Junction. Expect this to drop another .50 to 1 inch over zones 221 225 and 227 through Sat with the heaviest amounts in Denali Park. From .50-1.5 inch of rain has already fallen in Denali Park so this will keep small stream and rivers there high through the weekend and could still cause mud and rock slides. A second and weaker short wave trough near Old Crow will move to Fort Yukon by 4am Sat...to Denali to Livengood by 4pm Sat...and then slowly dissipate through Sun. This will cause scattered showers and scattered PM thunderstorms in eastern zone 216 western 221 and 227 Sat and into Sun. The thunderstorms could have small hail Sat. A third short wave trough over the southern Yukon Territory will move to the ALCAN Border by 4pm Sat and then weaken over the eastern Interior through Sun. This will bring more widespread showers to zones 224 226 Sat into Sun and keep scattered showers and at least isolated thunderstorms going in the remainder of the eastern Interior. There is the potential for hail again Sun and this will need to be watched. A fourth short wave is expected to move to the extreme SE interior Sun night and Mon and could bring heavy rain...but this still has a lot of uncertainty. Surface... An Arctic warm front from Barter Island to Deadhorse will move to Barter Island north by 4am Sat then move north of the coast. Expect fog to reform along this front tonight and then move offshore Sat. A 1022 mb high over the central Bering Sea will weaken slowly through Sun. An Arctic cold front in the western Chukchi Sea will move east to Barrow to Cape Lisburne then west by 4pm Sat...to Deadhorse to a 1007 mb low near Point Hope by 4am Sun...and then quasi- stationary. Fog and a chance of rain will accompany the front. Westerly flow will increase south of the low center and should return widespread fog to the southern Chukchi and north Bering Seas and most of the West Coast of AK by Sat night. && .DISCUSSION... Models are similar on the large scale flow pattern and features but differ some on timing and location of weak short wave troughs moving west across the Interior. Since these weak short wave troughs are the main force driving convection over the interior the location is important. We favor the GFS locations of the short waves and heavy rain through Sat night Sun and then the flow becomes so weak that we can really only deal with short wave location and accompanying rainfall in a probabilistic sense. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Continued wet across southern and eastern Interior with drier and warmer conditions in the northwest Interior. Expect isolated thunderstorms a a few lightning strikes today and Sat...except LAL 3 Sat in eastern Zone 216...western 221 and 227. Sun could see LAL 3 over the eastern Interior but uncertain at this point so left it as LAL 2 for Sun. && .HYDROLOGY... The past 36 hrs saw .10 to .25 inch of rain fall over the eastern Interior south of Circle with up to .50 inch in the hills north of Fox and hills east of Delta Junction...while Denali Park had between .50-1.5 inch. Expect another .50 to 1 inch over zones 221 225 and 227 through Sat with the heaviest amounts in Denali Park. This will keep small stream and rivers in Denali high through the weekend and could cause mud and rock slides through the weekend. There is a potential for heavy rain in zones 224 and 226 SE of Tok Sun night and Mon but still much uncertainty on this. && .AFG WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory for PKZ245. && $$ JB JUL 16
Southeast Alaska Forecast Discussion National Weather Service Juneau AK 533 AM AKDT FRI JUL 1 2016 .SHORT TERM...The biggest story over the next 24 hours is the ongoing glacial dam release from Suicide Basin into Mendenhall Lake and River. This will be covered further in the hydrology section below. As for the weather, the main feature is a 1000 mb low pressure system currently in the southeast gulf which will gradually weaken while moving north to near Cape Fairweather by late tonight. A secondary wave of low pressure will develop southwest of Haida Gwaii late tonight but is expected to remain south of the area. Stratiform rainfall is currently ongoing across the southern half of the panhandle aided by warm air advection in association with the advancing low. This will continue to spread northward through the day reaching the Juneau area this morning and the far northern panhandle this afternoon. Precipitation chances will remain high throughout the next 24 hours across all of Southeast Alaska. Expecting rainfall totals to generally range from one half of an inch to an inch with heaviest amounts over the southern panhandle. This system will enhance winds over the southern half of the area but am only expecting 10 to 20 mph for the land areas and 20-25 kt for the inner channels. Decreased winds across the far northern panhandle as a parallel pressure gradient to Northern Lynn Canal will lead to lighter winds. Used the 06z NAM and Hi-Res model guidance for updates to the short term period. Forecaster confidence is above average. .LONG TERM...Through the weekend, generally a zonal flow pattern in place across the north Pacific aloft. The closed low at 500 mb over the Gulf of Alaska weakens and moves into western Canada Monday while a broad weak ridge aloft forms over the western gulf. Weak to null flow aloft over the northern panhandle will be in place headed into early next week. Long range trend for Southeast Alaska looks to be for a development around mid week to the end of the week over the gulf. A surface low near Cape Fairweather is weakening, while a low moving across the southern gulf along 50N and then curving north across Haida Gwaii on Saturday. This will spread rain into the southern half of the panhandle. Saturday evening the low will move into British Columbia while the low off of Cross Sound dissipates. The surface pattern across the gulf Friday into Saturday becomes west to northwest. The potential for low probability showers from onshore flow will exist along the outer coast Sunday into Monday. With the main flow pattern to the south of the forecast area not expecting a significant weather system for the next few days. && .HYDROLOGY...Suicide Basin has released and a flood warning is in effect for Mendenhall River and Lake until Saturday morning. The current forecast crest of 11.6 feet is close to the previous record value of 11.85 feet set in 2014. As of early this morning, Mendenhall Lake had risen to a stage of 8.5 feet and the rate of rise is steadily increasing as expected. The level in Suicide Basin continues to fall rapidly. Residents near the lake or the river should remain alert and keep track of updates to this event as they are issued by NWS Juneau. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ033>036-041>043. && $$ TPS/Bezenek Visit us at http://www.weather.gov/Juneau
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 447 AM AKDT FRI JUL 1 2016 .ANALYSIS AND UPPER LEVELS... Upper level lows are over the western Bering and the southern Gulf of Ak this morning with the jet remaining well south of the forecast area. At the surface, lows are near Attu and over the eastern Gulf. A ridge of high pressure is over the eastern Bering. The thermal trough/theta-e ridge is draped along the Alaska and Aleutian ranges and is serving as the focus for showers and even a few nocturnal thunderstorms. && .MODEL DISCUSSION... Models remain in agreement that the Gulf upper low will slowly rotate its way into British Columbia by Sun morning. Easterly waves moving along the northern flank of the low will interact with the moisture rich thermal trough/theta-e ridge through the weekend. This may explain what is happening, but these waves are poorly timed in model solutions, so exactly when precipitation initiation and enhancement will occur remains a problem. The forecast utilizes some Nam and GFS in an attempt to pinpoint some of the precipitation events. In the west the surface low will drift and weaken over the western Aleutians through the weekend. A weak associated front will move to the central Aleutians during the same period. Again the Nam and GFS were utilized in the forecast. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... The last of a series of fairly strong short-waves crossing westward across Southcentral Alaska this morning will exit to Southwest Alaska this afternoon bringing an end to widespread showers and rain. However, as the large upper low over the Gulf tracks eastward today and tonight, short-waves tracking across Southwest Alaska will rotate southeastward across Kodiak Island and the western Gulf bringing widespread showers to that region. In the wake of the upper level low the flow across the region will become more and more chaotic, with weak impulses wandering around. This creates a lot of uncertainty in the forecast. Have used a broadbrush approach to the precip forecast for tonight through Saturday night. In this scenario would expect more showers during the afternoon and evening hours focused along the mountains. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... Clouds, rain, and thunderstorms will be the focus for Friday and Saturday. Widespread showers with embedded thunderstorms will encompass the Kuskokwim Valley southward through Greater Bristol Bay today. A lesser chance exists over the Kuskokwim Delta, but afternoon showers and a slight chance for thunder are possible. Nearly the same conditions are on tap for Saturday, however, any thunderstorms will stay confined to the Kuskokwim Valley along the Alaska Range. For the Delta, most of the shower activity will be east of Bethel along the Kilbucks. Winds will be on the lighter side everywhere, and temperatures will be well above average for this time of year. Technically speaking...A large upper level low in the gulf controls the pattern, but the real action is rotating around the circulation in the form of embedded easterly shortwaves. Feeding on the baroclinity from the difference between the cooler gulf airmass and the warmer Interior/Yukon airmass, these waves amplify and provide the forcing for diurnally enhanced showers and thunderstorms. Ridging over the northern portion of the state is breeding warm low level temperatures that will be advected down into the Southwest Mainland, as well as some juicy dewpoints by Alaska standards. These conditions are ripe for frequent lightning over mainly the Kuskokwim Valley and into Bristol Bay today. The upper level energy lingers through the weekend keeping at least showers in the forecast. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... A weakening system aloft over the Western Bering will bring rain today from Shemya through the Central Aleutians, and as far east as the Eastern Aleutians. That system will weaken through the weekend and not produce meaningful precipitation after today. A fairly narrow corridor of dense fog will set up today roughly from Saint Matthew through the Pribilofs and linger through tonight. && .LONG TERM FORECAST (Days 3 through 7)... On Sunday, the upper level pattern looks to grind to a halt from the easterly flow of weak disturbances to a much more chaotic movement. This will be due to the departure of the upper level low towards the Panhandle by Sunday morning, with no larger scale features following it. Thus, with everything being weak, any precipitation that develops Sunday over southern mainland Alaska will be scattered and weak. The persistence of a mid-level unstable layer over much of the area will result in some convection popping up with any showers that develop with enhanced lift, likely from topographic enhancement. For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...DS SOUTHCENTRAL ALASKA...SEB SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML LONG TERM...JW
Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 418 AM AKDT FRI JUL 1 2016 .DISCUSSION... UPPER AIR... A high pressure ridge currently extends from the Chukotsk Peninsula eastward across the Brooks Range into northwestern Canada, with a high center near the Bering Strait. The ridge will gradually transition to a high pressure center which will be pushed gradually eastward through Sunday night as a strong short wave drops southward out of the Russian Arctic Ocean. By late Sunday night the upper level high will be centered near Fort Yukon, with the strong short wave trough extending along 178W across the Chukchi Sea and Bering Sea. A series of weak short wave troughs will move westward across the southern interior through Saturday. A weak short wave trough is now moving westward across the central interior. The next short wave trough is now over the southern Yukon Territory and will move to the Alcan border by Friday morning then fracture into two troughs. The southern piece of the trough will continue to move westward and gradually deepen over the lower Kuskokwim Valley and southeastward Friday evening. The northern piece of the trough will stall out over the eastern interior Friday night and gradually weaken Saturday. SURFACE... A 1007 mb low centered near Northway will deepen to a 1001 mb low about 100 miles east of Northway by this afternoon, then remain nearly stationary through Saturday. A weak thermal trough will develop across the northern interior Saturday. INTERIOR... Areas or bands of showers and thunderstorms associated with the short wave troughs aloft will move westward across the southern interior and the Alaska Range, otherwise there will be isolated to scattered showers and isolated thunderstorms over most areas through the weekend. The heaviest rainfall today will likely be over Denali and the lower Kuskokwim Valley. The heaviest rainfall amounts tonight are expect to be in the lower Kuskokwim valley and in nearby area of the middle Yukon Valley. More showers and isolated thunderstorms are expected over much of the interior Saturday, and over much of the southern and eastern interior Sunday. ARCTIC SLOPE AND BROOKS RANGE... Areas of fog near the coast during the late night and early morning hours, otherwise no significant weather expected through Sunday. Warm temperatures in the interior with highs as high as the low to mid 70s. WEST COAST... No significant weather expected through Sunday. Some coastal areas may see areas of fog. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Some warming is expected in the interior over the weekend...with highs approaching or reaching 80 in some northern interior areas. Minimum humidities could approach 30 percent in the northern interior. Minimum humidities in the southern interior likely to remain at 35 percent or above. && .HYDROLOGY... Additional rainfall amounts of 0.5 to 1 inch are expected in Denali and the lower Kuskokwim Valley today. Northern parts of the Upper Tanana Valley and Fortymile country may see up to 0.5 inch, with local amounts of 0.75 inch possible. Locally heavier amounts will be possible in Denali and the lower Kuskokwim Valley today, but the location of the amounts remains uncertain due to the convective nature of the precipitation. && .AFG WATCHES/WARNINGS/ADVISORIES... Small craft advisory for PKZ245. && $$ RF JUN 16
Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 418 AM AKDT FRI JUL 1 2016 .DISCUSSION... UPPER AIR... A high pressure ridge currently extends from the Chukotsk Peninsula eastward across the Brooks Range into northwestern Canada, with a high center near the Bering Strait. The ridge will gradually transition to a high pressure center which will be pushed gradually eastward through Sunday night as a strong short wave drops southward out of the Russian Arctic Ocean. By late Sunday night the upper level high will be centered near Fort Yukon, with the strong short wave trough extending along 178W across the Chukchi Sea and Bering Sea. A series of weak short wave troughs will move westward across the southern interior through Saturday. A weak short wave trough is now moving westward across the central interior. The next short wave trough is now over the southern Yukon Territory and will move to the Alcan border by Friday morning then fracture into two troughs. The southern piece of the trough will continue to move westward and gradually deepen over the lower Kuskokwim Valley and southeastward Friday evening. The northern piece of the trough will stall out over the eastern interior Friday night and gradually weaken Saturday. SURFACE... A 1007 mb low centered near Northway will deepen to a 1001 mb low about 100 miles east of Northway by this afternoon, then remain nearly stationary through Saturday. A weak thermal trough will develop across the northern interior Saturday. INTERIOR... Areas or bands of showers and thunderstorms associated with the short wave troughs aloft will move westward across the southern interior and the Alaska Range, otherwise there will be isolated to scattered showers and isolated thunderstorms over most areas through the weekend. The heaviest rainfall today will likely be over Denali and the lower Kuskokwim Valley. The heaviest rainfall amounts tonight are expect to be in the lower Kuskokwim valley and in nearby area of the middle Yukon Valley. More showers and isolated thunderstorms are expected over much of the interior Saturday, and over much of the southern and eastern interior Sunday. ARCTIC SLOPE AND BROOKS RANGE... Areas of fog near the coast during the late night and early morning hours, otherwise no significant weather expected through Sunday. Warm temperatures in the interior with highs as high as the low to mid 70s. WEST COAST... No significant weather expected through Sunday. Some coastal areas may see areas of fog. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Some warming is expected in the interior over the weekend...with highs approaching or reaching 80 in some northern interior areas. Minimum humidities could approach 30 percent in the northern interior. Minimum humidities in the southern interior likely to remain at 35 percent or above. && .HYDROLOGY... Additional rainfall amounts of 0.5 to 1 inch are expected in Denali and the lower Kuskokwim Valley today. Northern parts of the Upper Tanana Valley and Fortymile country may see up to 0.5 inch, with local amounts of 0.75 inch possible. Locally heavier amounts will be possible in Denali and the lower Kuskokwim Valley today, but the location of the amounts remains uncertain due to the convective nature of the precipitation. && .AFG WATCHES/WARNINGS/ADVISORIES... Small craft advisory for PKZ245. && $$ RF JUN 16
Southcentral and Southwest Alaska Forecast Discussion...CORRECTED National Weather Service Anchorage AK 1108 PM AKDT THU JUN 30 2016 Corrected extended discussion .ANALYSIS AND UPPER LEVELS... The upper levels are starting to look like a mixed bag of goodies. The ever present upper level low spinning south of the gulf is slowly weakening but is continuing to eject shortwaves around it. The first of these waves moved across Southcentral last evening. The next is to the Northwest of PAYA and is noted on upper level analysis as an enhanced bubble of moisture and as a wiggle in the upper level analysis. This wave will move across the ALCAN border and across the Copper River Basin this afternoon. As of 2130z(1:30pm AKDT), showers are already beginning to form. This easterly wave will wrap around the low and slide across the Anchorage and Kenai areas tonight. A much more potent wave is easily identified in water vapor imagery near 49N 141W. As is the case with nearly stationary lows and these easterly waves that get ejected around, timing and placement has been a challenge. This strong wave is now progged to shift east and impact SE AK and BC. Farther west, a ridge between the Gulf low and a weakening Bering low is becoming pinched off as it retreats into the interior of Alaska. A strong upper level jet remains well south of the forecast area. At the surface, progress is being made on moving the nearly stationary low out of the gulf. A stalled out front stretches from a low in the Bering and southeast across the Akpen. && .MODEL DISCUSSION... All models are in pretty good agreement in the short term today. As briefly touched on in the analysis...the upper level low in the Gulf will shift east into the weaken. All of the models have varying levels of agreement with the shortwave strength and timing moving around the lows. The biggest trend from yesterday was slowing down the timing of the onset of the biggest rainmaker over Anchorage. The latest 18z runs of the NAM and GFS are showing a 9-12z time frame while the HRRR is hinting at an early start, between 5 and 6z. Judging by past performance of the HRRR and how poorly the major models play temporally, confidence in timing is low. However, all models are consistent with bringing in a healthy amount of rain across the region. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... Increasing mass ascent ahead of a low amplitude short wave trough over the Western Yukon and Eastern Copper Basin is beginning to manifest itself as increasing convective showers across the region. As the shortwave propagates west tonight, showers will begin to congeal into a large area of stratiform rain which will impact all of Southcentral tonight with brief periods of heavy rainfall. The heaviest axis of rain will likely occur across the Copper Basin into the Mat-Su Valleys, although areas along the Kenai and into Anchorage will also see the potential for brief heavy rains overnight. Thunderstorms have formed already along the Kenai Range, and they will also be possible along the Talkeetnas and Alaska Range as well as along the Chugach in the evening. The shortwave trough will elongate and quickly move west Friday, with most rain moving into Southwest Alaska by the afternoon. Showers will develop in the afternoon behind the main low, but these will be mainly along mountains and rather limited given lack of instability. Saturday will be warmer as broad cyclonic flow sets up over the region, with more afternoon showers but slightly warming temperatures. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... The upper level low over the Gulf continues to bring easterly flow with embedded shortwaves over Southwest Alaska. This combined with the unstable environment is helping to kick off thunderstorms over the area through Friday. The most likely times for thunderstorms are during peak heating and as the shortwaves move through. The shortwaves look to move through this evening, Friday morning and Friday evening. Friday will also see heavier rain from the Kuskokwim Valley south towards Bristol Bay and east towards the Alaska and Aleutian Ranges. Saturday will see a lesser chance for thunderstorms with the most likely area over the Kuskokwim Vally but rain will still be likely from the valley through Bristol Bay. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... A broad low over the Western Aleutians will last through the weekend slowly tracking east and bringing rain to the area. Areas from the Alaska Peninsula through the Pribilof Islands will be under the effects of weak ridging providing more fair conditions than areas to the west. && .LONG TERM FORECAST (Days 3 through 7)... On Sunday, the upper level pattern looks to grind to a halt from the easterly flow of weak disturbances to a much more chaotic movement. This will be due to the departure of the upper level low towards the Panhandle by Sunday morning, with no larger scale features following it. Thus, with everything being weak, any precipitation that develops Sunday over southern mainland Alaska will be scattered and weak. The persistence of a mid-level unstable layer over much of the area will result in some convection popping up with any showers that develop with enhanced lift, likely from topographic enhancement. For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...SS SOUTHCENTRAL ALASKA...JA SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK LONG TERM...JW
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
304 AM CDT SAT JUL 2 2016 .SHORT TERM...(Today and Tonight) Issued at 304 AM CDT SAT JUL 2 2016 Upper trough axis this morning per water vapor imagery centers over central CO with several embedded waves ejecting eastward across the central plains. Closer to the sfc, a warm front stretched southwest to northeast across central KS, with a stout low level jet from the southwest maintaining an MCS across western and central Kansas. High precipitable water values and effective shear values to 40 kts from the west look to maintain this complex into the day Saturday. Radar analysis suggest high rainfall rates up to 2 inches per hour within the heavier bands, progged to enter Dickinson, Morris, and Lyon counties within the next few hours. Radar estimates at this time towards Great Bend are between 3 and 4 inches thus far and are likely to climb. Short term guidance confirms the forecast analysis for this MCS to gradually lift northeast across our CWA through the early afternoon today as the inverted trough axis shifts eastward,lifting the warm front into the CWA. Dewpoints increase back into the 70s while PWAT values average over 2 inches. Warm precipitation processes will create healthy precip rates on average between 1 and 2 inches per hour through the morning hours. Localized flooding will be possible with this complex as Flash Flood Guidance values average around 2-3 inches for 1 hour. There may be a lull in precipitation in the afternoon, especially from the Interstate 70 corridor and locations southward as temporary subsidence fills in behind the departing MCS. Some clearing of cloud cover over far east central areas may help raise highs to the middle 80s with 70s likely for much of the forecast area. Next upper shortwave trough ejects east over northern KS this evening, reinforcing showers and thunderstorms along the front initially centered north of Interstate 70 in the early evening period. Any convection that develops during the late afternoon may reach severe limits as MUCAPE values exceed 2000 J/KG while shear values increase to near 40 kts. Main hazards would be the damaging winds and small hail in addition to the heavy rainfall. The severe threat should begin to wane overnight as the focus turns to the heavy rainfall and localized flash flooding threat. The frontal boundary and MCS drops southward overnight with another round of heavy precipitation likely. Much of northeast Kansas should expect to see decent rainfall with totals ranging from an additional 1 to 3 inches. .LONG TERM...(Sunday through Friday) Issued at 304 AM CDT SAT JUL 2 2016 For Sunday, models are a little more similar in timing the inverted surface trough`s movement to the southeast, generally taking it out of the forecast area by Sunday afternoon. The GFS remains the slower solution and shows some potential for precip to linger across Anderson CO Sunday evening. Otherwise the overall trend is for precip chances to be winding down as the deeper moisture axis shifts southeast and the low amplitude shortwave propagates east. Have held onto some small POPs Sunday night across east central KS, but think there may be a better chance precip comes to an end by the evening hours. Highs Sunday should remain well below normal due to cloud cover and morning precip. Think highs will range from the lower 70s near the NEB state line to near 80 over Anderson CO. Forecast soundings keep the low levels saturated through Monday morning and think there could be some low stratus through a good part of the morning until the boundary layer mixes out. Because of this, have not gone quite as cool for Lows Monday keeping temps in the lower 60s. Aside from the morning clouds, Independence Day looks to be nice due to subsidence in the wake of the upper shortwave allowing skies to become partly sunny by the afternoon. Weak surface ridging and no real warm air advection is expected to keep highs in the lower and mid 80s. For Tuesday through Friday, the biggest change to the weather will be a return to summer heat. Models continue to show hot air advecting into the central plains from the southwest, and the GFS still suggests some triple digit readings are possible by Thursday. Think that the expected rainfall saturating the soil may help to moderate the magnitude of the warm up so the forecast keeps highs in the 90s through the end of the work week. The soil moisture may also add to the low level humidity and as a result the forecast is showing heat indices around 105 for the last half of the work week. There are some small precip chances Tuesday and Tuesday night with models showing a weak shortwave moving across the region. After Tuesday night, precip chances are a little more questionable as the GFS advects in a decent elevated mixed layer to cap the boundary layer. The ECMWF has taken to showing the potential for nocturnal MCS development somewhere over the central plains by the end of the week. Because of this have some small POPs for Thursday night. We`ll have to monitor the potential for nightly MCS development as it would have an impact on temperatures as well as area rivers. && .AVIATION...(For the 06Z TAFS through 06Z Saturday Night) Issued at 1134 PM CDT FRI JUL 1 2016 Main concern for this forecast will be convection timing and duration at the terminals. Complex of tsra in western and central KS should move into the MHK area around 08Z and TOP and FOE in the 09Z-10Z period. Expect tsra to continue in local area through 17Z then diminish before increasing chances once again after 01Z Sun. Cigs vfr and vsbys will vary from vfr to mvfr or ifr at times through the period. Expect brief cigs of mvfr with some of the storms. WInds east around 10 kts or less through the period. && .TOP Watches/Warnings/Advisories... Flash Flood Watch through Sunday evening for KSZ024-026-038>040- 054>056-058-059. Flash Flood Watch through Sunday morning for KSZ008>012-020>023- 034>037. && $$ SHORT TERM...Prieto LONG TERM...Wolters AVIATION...53
Area Forecast Discussion National Weather Service Dodge City KS 220 AM CDT SAT JUL 2 2016 ...Updated short term section... .SHORT TERM...(Today and tonight) Issued at 219 AM CDT Sat Jul 2 2016 Scattered thunderstorms will move east out of the area this morning leaving partly to mostly cloudy skies across western Kansas through this afternoon. Winds will be shifting from an easterly direction this morning to more of a southerly direction by this afternoon. This is due to a warm front being pushed northward into northern Kansas. These southerly winds will be short lived as models suggest a shortwave moving out of the Central Rockies into the Plains by this evening helping push this frontal boundary back south through the CWA tonight. This will allow winds to shift to more of a northerly direction behind the front starting across west central Kansas this evening then through the remainder of the CWA tonight. Another cluster of thunderstorms are anticipated to form along and ahead of this frontal boundary starting in the late afternoon and continuing into the overnight hours. However, thunderstorm chances end from northwest to southeast tonight and should be confined to south central Kansas by sunrise Sunday. Otherwise expect mostly cloudy skies tonight. As for temperatures, highs today look to range from the upper 70s across central Kansas to around 90 degrees along the KS/OK border. Lows tonight are expected to range from the lower 60s across west central Kansas to upper 60 across south central Kansas. .LONG TERM...(Saturday night through Friday) Issued at 307 PM CDT Fri Jul 1 2016 For Saturday night, a cold front will continue to move east into central Kansas with lingering strong to severe thunderstorms mainly east of Dodge City into parts of south central Kansas. Then for Sunday into next Friday, a mainly dry period is forecast with a warming trend. Highs warm from the 80s Sunday and around 90 for Monday, the 4th of July, into the mid to upper 90s from Tuesday into next Friday, as warmer upper level ridging builds into the Central Plains. Overnight lows will gradually warm also from 60s into the 70s. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1206 AM CDT Sat Jul 2 2016 Another cluster of thunderstorms will move across western Kansas early this morning bringing MVFR to IFR conditions to the TAF sites. These storms should move away from the TAF sites by sunrise with VFR conditions for the remainder of the morning into the early afternoon. Another round of thunderstorms is possible again tomorrow evening into the overnight period. Winds will generally start out from the southeast at less than 10 knots shifting to more of a southerly direction after sunrise into the afternoon hours. The only exception to this will be around the thunderstorms this morning where gusty winds will be found. && .PRELIMINARY POINT TEMPS/POPS... DDC 85 63 81 62 / 60 70 20 10 GCK 84 61 83 63 / 70 70 10 10 EHA 86 64 87 64 / 60 70 10 10 LBL 88 64 85 64 / 50 70 20 10 HYS 81 61 78 60 / 70 70 10 10 P28 90 69 84 64 / 40 90 20 10 && .DDC Watches/Warnings/Advisories... Flash Flood Watch until 7 AM CDT /6 AM MDT/ this morning for KSZ043-044-061>063-074-075. && $$ SHORT TERM...Hovorka_42 LONG TERM...Kruse AVIATION...Hovorka_42
Area Forecast Discussion National Weather Service Dodge City KS 220 AM CDT SAT JUL 2 2016 ...Updated short term section... .SHORT TERM...(Today and tonight) Issued at 219 AM CDT Sat Jul 2 2016 Scattered thunderstorms will move east out of the area this morning leaving partly to mostly cloudy skies across western Kansas through this afternoon. Winds will be shifting from an easterly direction this morning to more of a southerly direction by this afternoon. This is due to a warm front being pushed northward into northern Kansas. These southerly winds will be short lived as models suggest a shortwave moving out of the Central Rockies into the Plains by this evening helping push this frontal boundary back south through the CWA tonight. This will allow winds to shift to more of a northerly direction behind the front starting across west central Kansas this evening then through the remainder of the CWA tonight. Another cluster of thunderstorms are anticipated to form along and ahead of this frontal boundary starting in the late afternoon and continuing into the overnight hours. However, thunderstorm chances end from northwest to southeast tonight and should be confined to south central Kansas by sunrise Sunday. Otherwise expect mostly cloudy skies tonight. As for temperatures, highs today look to range from the upper 70s across central Kansas to around 90 degrees along the KS/OK border. Lows tonight are expected to range from the lower 60s across west central Kansas to upper 60 across south central Kansas. .LONG TERM...(Saturday night through Friday) Issued at 307 PM CDT Fri Jul 1 2016 For Saturday night, a cold front will continue to move east into central Kansas with lingering strong to severe thunderstorms mainly east of Dodge City into parts of south central Kansas. Then for Sunday into next Friday, a mainly dry period is forecast with a warming trend. Highs warm from the 80s Sunday and around 90 for Monday, the 4th of July, into the mid to upper 90s from Tuesday into next Friday, as warmer upper level ridging builds into the Central Plains. Overnight lows will gradually warm also from 60s into the 70s. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1206 AM CDT Sat Jul 2 2016 Another cluster of thunderstorms will move across western Kansas early this morning bringing MVFR to IFR conditions to the TAF sites. These storms should move away from the TAF sites by sunrise with VFR conditions for the remainder of the morning into the early afternoon. Another round of thunderstorms is possible again tomorrow evening into the overnight period. Winds will generally start out from the southeast at less than 10 knots shifting to more of a southerly direction after sunrise into the afternoon hours. The only exception to this will be around the thunderstorms this morning where gusty winds will be found. && .PRELIMINARY POINT TEMPS/POPS... DDC 85 63 81 62 / 60 70 20 10 GCK 84 61 83 63 / 70 70 10 10 EHA 86 64 87 64 / 60 70 10 10 LBL 88 64 85 64 / 50 70 20 10 HYS 81 61 78 60 / 70 70 10 10 P28 90 69 84 64 / 40 90 20 10 && .DDC Watches/Warnings/Advisories... Flash Flood Watch until 7 AM CDT /6 AM MDT/ this morning for KSZ043-044-061>063-074-075. && $$ SHORT TERM...Hovorka_42 LONG TERM...Kruse AVIATION...Hovorka_42
Area Forecast Discussion National Weather Service Goodland KS 1158 PM MDT FRI JUL 1 2016 .UPDATE... Issued at 1158 PM MDT Fri Jul 1 2016 Update to cancel flash flood watch. Flash flood threat has diminished as only showers and a few weaker thunderstorms remain in our CWA (with watch area thunderstorm- free). I can rule out additional showers or thunderstorms, but heavy rain threat has ended for the night in our area. UPDATE Issued at 822 PM MDT Fri Jul 1 2016 Continued Flash Flood Watch as potential for slow moving thunderstorms continues over the watch area. With 1hr and 3hr FFG in the 1.5 to 2 inch range in the watch area any slow moving thunderstorm would potentially lead to flash flooding. Better instability is in the south at this time, however there is still enough instability to still support isolated to scattered stronger storms along the Colorado/Kansas state line, with short range guidance still showing several clusters moving across our CWA. If activity ends up merging into larger moderate rain area with stronger storms in the south (where more favorable environment is) we may see decreased flash flood potential. No changes were planned as current trends haven`t lowered confidence yet in flood potential. && .SHORT TERM...(This evening through Saturday) Issued at 138 PM MDT Fri Jul 1 2016 As of 2 PM CDT, 1 PM MDT, skies across the Tri-State Region are overcast. Temperatures have risen into the upper 60s to upper 70s. The warmest temperatures have been observed east of highway 25 where low clouds were slower to arrive. Winds are southeast at 5-15 mph, gusting to 25 mph in a few spots. At the surface, a low pressure was centered over northern New Mexico. In addition, a stalled front is located over eastern Colorado and southwest Kansas. Aloft, a substantial plume of moisture with an associated shortwave trough are moving northeast across southwest Colorado. For the rest of the afternoon through tonight, a very moist atmosphere will combine with a passing upper level disturbance moving across the region, leading to widespread thunderstorm development. Precipitable water readings, already at least 2 standard deviations above normal, are expected to increase further this evening with low level flow from the southeast and upper level monsoonal flow. As an upper level disturbance moves out into the High Plains, thunderstorms will develop along the Rockies and spread east. The development phase is already underway. Further, the surface low over New Mexico will spread northeast through the night. Frontogenetic lift on the northwest side of the low should help sustain a large area of thunderstorms over northwest Kansas as they move through this evening or tonight. As for timing, expecting the heavy rain producing thunderstorms to move into east Colorado this evening around 6 PM MDT. The storms will continue spreading east, reaching SW Nebraska and NW Kansas by 9 PM MDT. Thunderstorms may not completely exit the region until early tomorrow morning. Also, a few showers and storms may develop in an increasingly unstable atmosphere this afternoon east of highway 25. This new development over Kansas and Nebraska shouldn`t amount to much. The complex of storms moving in this evening is the one to watch. As for severe weather potential, overall feel that the severe potential is fairly low. Would not anticipate widespread severe weather with this event. Instability and shear parameters indicate that a few strong to severe thunderstorms are possible. The main threats with these storms would be marginally severe hail and damaging downburst winds. The primary threat with thunderstorms tonight will be heavy rainfall and flash flooding. Couldn`t find a reason to get rid of the flash flood watch due to slow storm movement, heavy rainfall observed over the watch area last night, highly anomalous precipitable water readings and multiple forcing mechanisms. Locations south of a line from Norton, Kansas to Flagler, Colorado stand the best chance for heavy rainfall this evening/tonight and possibly multiple rounds as well. For tomorrow, a lull in precipitation chances is forecast during the morning hours as most thunderstorm activity should have exited to the east. Another shortwave trough slides over the High Plains by tomorrow afternoon. Do expect shower/thunderstorm development as this occurs, primarily over SW Nebraska and NW Kansas. The threat for heavy rainfall should remain with precipitable water readings still expected to be around 2 standard deviations above normal. .LONG TERM...(Saturday night through Friday) Issued at 320 PM MDT Fri Jul 1 2016 The recent wet and cool weather will transition to a hotter and dryer pattern from Sunday through the middle of next week. Saturday night the upper trough that was moving through the region during on Saturday is expected to move east of the region overnight. Short wave ridging is expected through Monday with a dirty westerly flow turning more southwesterly by late in the week. As a result, other than a very isolated late day thunderstorm or two, mostly dry conditions are expected from Sunday through Wednesday morning. Then as the flow becomes more southwesterly aloft later in the week, a more "monsoonal" pattern develops with disturbances and elevated moisture moving out of the west southwest, east of the Rockies, and across the high plains. This will produce mainly isolated thunderstorms each afternoon and evening. The moist upslope return flow moves out of the region Sunday night as a surface lee trough develops along the Rocky Mountain front range. This turns the near surface flow more southwesterly and keeps the near surface environment mostly dry. Superblend is giving high temperatures in the 90s through next week, but could definitely see a return of the lower 100 degree temperatures Wednesday and Thursday as has been indicated by the GFS. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1131 PM MDT Fri Jul 1 2016 Showers/thunderstorms continue to impact both KGLD and KMCK early in the TAF period with decreasing chances through the night. Redevelopment may occur Saturday afternoon after a lull Saturday morning, however trends have been towards lower coverage than originally indicated. A very moist air mass remains in place, however the convection earlier disrupted low level flow and now short range guidance is not as pessimistic as earlier this evening. I trended current TAFs towards consensus which still favors IFR cigs at KMCK, however now it appears that CIGS should remain MVFR at KGLD through Saturday morning. Another round of low stratus will be possible Saturday evening and Saturday night with progression from the north to the south, meaning KMCK is in line for lowest conditions and impacts earlier. IFR was introduced at KMCK during the evening in line with all current guidance. Lowest cigs and possible fog would be after the current valid TAF period. && .GLD Watches/Warnings/Advisories... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...DR SHORT TERM...RRH LONG TERM...LOCKHART AVIATION...DR
Area Forecast Discussion National Weather Service Goodland KS 1158 PM MDT FRI JUL 1 2016 .UPDATE... Issued at 1158 PM MDT Fri Jul 1 2016 Update to cancel flash flood watch. Flash flood threat has diminished as only showers and a few weaker thunderstorms remain in our CWA (with watch area thunderstorm- free). I can rule out additional showers or thunderstorms, but heavy rain threat has ended for the night in our area. UPDATE Issued at 822 PM MDT Fri Jul 1 2016 Continued Flash Flood Watch as potential for slow moving thunderstorms continues over the watch area. With 1hr and 3hr FFG in the 1.5 to 2 inch range in the watch area any slow moving thunderstorm would potentially lead to flash flooding. Better instability is in the south at this time, however there is still enough instability to still support isolated to scattered stronger storms along the Colorado/Kansas state line, with short range guidance still showing several clusters moving across our CWA. If activity ends up merging into larger moderate rain area with stronger storms in the south (where more favorable environment is) we may see decreased flash flood potential. No changes were planned as current trends haven`t lowered confidence yet in flood potential. && .SHORT TERM...(This evening through Saturday) Issued at 138 PM MDT Fri Jul 1 2016 As of 2 PM CDT, 1 PM MDT, skies across the Tri-State Region are overcast. Temperatures have risen into the upper 60s to upper 70s. The warmest temperatures have been observed east of highway 25 where low clouds were slower to arrive. Winds are southeast at 5-15 mph, gusting to 25 mph in a few spots. At the surface, a low pressure was centered over northern New Mexico. In addition, a stalled front is located over eastern Colorado and southwest Kansas. Aloft, a substantial plume of moisture with an associated shortwave trough are moving northeast across southwest Colorado. For the rest of the afternoon through tonight, a very moist atmosphere will combine with a passing upper level disturbance moving across the region, leading to widespread thunderstorm development. Precipitable water readings, already at least 2 standard deviations above normal, are expected to increase further this evening with low level flow from the southeast and upper level monsoonal flow. As an upper level disturbance moves out into the High Plains, thunderstorms will develop along the Rockies and spread east. The development phase is already underway. Further, the surface low over New Mexico will spread northeast through the night. Frontogenetic lift on the northwest side of the low should help sustain a large area of thunderstorms over northwest Kansas as they move through this evening or tonight. As for timing, expecting the heavy rain producing thunderstorms to move into east Colorado this evening around 6 PM MDT. The storms will continue spreading east, reaching SW Nebraska and NW Kansas by 9 PM MDT. Thunderstorms may not completely exit the region until early tomorrow morning. Also, a few showers and storms may develop in an increasingly unstable atmosphere this afternoon east of highway 25. This new development over Kansas and Nebraska shouldn`t amount to much. The complex of storms moving in this evening is the one to watch. As for severe weather potential, overall feel that the severe potential is fairly low. Would not anticipate widespread severe weather with this event. Instability and shear parameters indicate that a few strong to severe thunderstorms are possible. The main threats with these storms would be marginally severe hail and damaging downburst winds. The primary threat with thunderstorms tonight will be heavy rainfall and flash flooding. Couldn`t find a reason to get rid of the flash flood watch due to slow storm movement, heavy rainfall observed over the watch area last night, highly anomalous precipitable water readings and multiple forcing mechanisms. Locations south of a line from Norton, Kansas to Flagler, Colorado stand the best chance for heavy rainfall this evening/tonight and possibly multiple rounds as well. For tomorrow, a lull in precipitation chances is forecast during the morning hours as most thunderstorm activity should have exited to the east. Another shortwave trough slides over the High Plains by tomorrow afternoon. Do expect shower/thunderstorm development as this occurs, primarily over SW Nebraska and NW Kansas. The threat for heavy rainfall should remain with precipitable water readings still expected to be around 2 standard deviations above normal. .LONG TERM...(Saturday night through Friday) Issued at 320 PM MDT Fri Jul 1 2016 The recent wet and cool weather will transition to a hotter and dryer pattern from Sunday through the middle of next week. Saturday night the upper trough that was moving through the region during on Saturday is expected to move east of the region overnight. Short wave ridging is expected through Monday with a dirty westerly flow turning more southwesterly by late in the week. As a result, other than a very isolated late day thunderstorm or two, mostly dry conditions are expected from Sunday through Wednesday morning. Then as the flow becomes more southwesterly aloft later in the week, a more "monsoonal" pattern develops with disturbances and elevated moisture moving out of the west southwest, east of the Rockies, and across the high plains. This will produce mainly isolated thunderstorms each afternoon and evening. The moist upslope return flow moves out of the region Sunday night as a surface lee trough develops along the Rocky Mountain front range. This turns the near surface flow more southwesterly and keeps the near surface environment mostly dry. Superblend is giving high temperatures in the 90s through next week, but could definitely see a return of the lower 100 degree temperatures Wednesday and Thursday as has been indicated by the GFS. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1131 PM MDT Fri Jul 1 2016 Showers/thunderstorms continue to impact both KGLD and KMCK early in the TAF period with decreasing chances through the night. Redevelopment may occur Saturday afternoon after a lull Saturday morning, however trends have been towards lower coverage than originally indicated. A very moist air mass remains in place, however the convection earlier disrupted low level flow and now short range guidance is not as pessimistic as earlier this evening. I trended current TAFs towards consensus which still favors IFR cigs at KMCK, however now it appears that CIGS should remain MVFR at KGLD through Saturday morning. Another round of low stratus will be possible Saturday evening and Saturday night with progression from the north to the south, meaning KMCK is in line for lowest conditions and impacts earlier. IFR was introduced at KMCK during the evening in line with all current guidance. Lowest cigs and possible fog would be after the current valid TAF period. && .GLD Watches/Warnings/Advisories... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...DR SHORT TERM...RRH LONG TERM...LOCKHART AVIATION...DR
Area Forecast Discussion National Weather Service Goodland KS 1131 PM MDT FRI JUL 1 2016 .UPDATE... Issued at 822 PM MDT Fri Jul 1 2016 Continued Flash Flood Watch as potential for slow moving thunderstorms continues over the watch area. With 1hr and 3hr FFG in the 1.5 to 2 inch range in the watch area any slow moving thunderstorm would potentially lead to flash flooding. Better instability is in the south at this time, however there is still enough instability to still support isolated to scattered stronger storms along the Colorado/Kansas state line, with short range guidance still showing several clusters moving across our CWA. If activity ends up merging into larger moderate rain area with stronger storms in the south (where more favorable environment is) we may see decreased flash flood potential. No changes were planned as current trends haven`t lowered confidence yet in flood potential. && .SHORT TERM...(This evening through Saturday) Issued at 138 PM MDT Fri Jul 1 2016 As of 2 PM CDT, 1 PM MDT, skies across the Tri-State Region are overcast. Temperatures have risen into the upper 60s to upper 70s. The warmest temperatures have been observed east of highway 25 where low clouds were slower to arrive. Winds are southeast at 5-15 mph, gusting to 25 mph in a few spots. At the surface, a low pressure was centered over northern New Mexico. In addition, a stalled front is located over eastern Colorado and southwest Kansas. Aloft, a substantial plume of moisture with an associated shortwave trough are moving northeast across southwest Colorado. For the rest of the afternoon through tonight, a very moist atmosphere will combine with a passing upper level disturbance moving across the region, leading to widespread thunderstorm development. Precipitable water readings, already at least 2 standard deviations above normal, are expected to increase further this evening with low level flow from the southeast and upper level monsoonal flow. As an upper level disturbance moves out into the High Plains, thunderstorms will develop along the Rockies and spread east. The development phase is already underway. Further, the surface low over New Mexico will spread northeast through the night. Frontogenetic lift on the northwest side of the low should help sustain a large area of thunderstorms over northwest Kansas as they move through this evening or tonight. As for timing, expecting the heavy rain producing thunderstorms to move into east Colorado this evening around 6 PM MDT. The storms will continue spreading east, reaching SW Nebraska and NW Kansas by 9 PM MDT. Thunderstorms may not completely exit the region until early tomorrow morning. Also, a few showers and storms may develop in an increasingly unstable atmosphere this afternoon east of highway 25. This new development over Kansas and Nebraska shouldn`t amount to much. The complex of storms moving in this evening is the one to watch. As for severe weather potential, overall feel that the severe potential is fairly low. Would not anticipate widespread severe weather with this event. Instability and shear parameters indicate that a few strong to severe thunderstorms are possible. The main threats with these storms would be marginally severe hail and damaging downburst winds. The primary threat with thunderstorms tonight will be heavy rainfall and flash flooding. Couldn`t find a reason to get rid of the flash flood watch due to slow storm movement, heavy rainfall observed over the watch area last night, highly anomalous precipitable water readings and multiple forcing mechanisms. Locations south of a line from Norton, Kansas to Flagler, Colorado stand the best chance for heavy rainfall this evening/tonight and possibly multiple rounds as well. For tomorrow, a lull in precipitation chances is forecast during the morning hours as most thunderstorm activity should have exited to the east. Another shortwave trough slides over the High Plains by tomorrow afternoon. Do expect shower/thunderstorm development as this occurs, primarily over SW Nebraska and NW Kansas. The threat for heavy rainfall should remain with precipitable water readings still expected to be around 2 standard deviations above normal. .LONG TERM...(Saturday night through Friday) Issued at 320 PM MDT Fri Jul 1 2016 The recent wet and cool weather will transition to a hotter and dryer pattern from Sunday through the middle of next week. Saturday night the upper trough that was moving through the region during on Saturday is expected to move east of the region overnight. Short wave ridging is expected through Monday with a dirty westerly flow turning more southwesterly by late in the week. As a result, other than a very isolated late day thunderstorm or two, mostly dry conditions are expected from Sunday through Wednesday morning. Then as the flow becomes more southwesterly aloft later in the week, a more "monsoonal" pattern develops with disturbances and elevated moisture moving out of the west southwest, east of the Rockies, and across the high plains. This will produce mainly isolated thunderstorms each afternoon and evening. The moist upslope return flow moves out of the region Sunday night as a surface lee trough develops along the Rocky Mountain front range. This turns the near surface flow more southwesterly and keeps the near surface environment mostly dry. Superblend is giving high temperatures in the 90s through next week, but could definitely see a return of the lower 100 degree temperatures Wednesday and Thursday as has been indicated by the GFS. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1131 PM MDT Fri Jul 1 2016 Showers/thunderstorms continue to impact both KGLD and KMCK early in the TAF period with decreasing chances through the night. Redevelopment may occur Saturday afternoon after a lull Saturday morning, however trends have been towards lower coverage than originally indicated. A very moist air mass remains in place, however the convection earlier disrupted low level flow and now short range guidance is not as pessimistic as earlier this evening. I trended current TAFs towards consensus which still favors IFR cigs at KMCK, however now it appears that CIGS should remain MVFR at KGLD through Saturday morning. Another round of low stratus will be possible Saturday evening and Saturday night with progression from the north to the south, meaning KMCK is in line for lowest conditions and impacts earlier. IFR was introduced at KMCK during the evening in line with all current guidance. Lowest cigs and possible fog would be after the current valid TAF period. && .GLD Watches/Warnings/Advisories... KS...Flash Flood Watch until 4 AM MDT /5 AM CDT/ Saturday for KSZ013- 027-028-041-042. CO...Flash Flood Watch until 4 AM MDT Saturday for COZ091-092. NE...NONE. && $$ UPDATE...DR SHORT TERM...RRH LONG TERM...LOCKHART AVIATION...DR
Area Forecast Discussion National Weather Service Dodge City KS 1210 AM CDT SAT JUL 2 2016 ...Updated aviation section... .UPDATE... Issued at 926 PM CDT Fri Jul 1 2016 Given radar trends of a strengthening QLCS complex entering the western zones, and an extremely moist airmass (dewpoints approaching 70 and PW near 1.5 inch), decided to post a flash flood watch for the NW zones through 7 AM Saturday. Latest HRRR drives a large MCS across the CWA overnight, as such, some flooding is possible south of this watch area. Storms are also intensifying in SE Colorado, so some severe weather is possible for the next several hours. UPDATE Issued at 525 PM CDT Fri Jul 1 2016 Updated rainfall/thunderstorm coverage in the grids, along with QPF/wx/sky grids, to align with radar/satellite trends, the neighboring WFOs, and the HRRR forecasts through tonight. Radar trends show strong to severe convection west of Lamar and approaching Elkhart. In the short term, there will be a limited threat of severe weather across far SW Kansas, where the instability axis resides, with ML CAPE near 2000 J/kg. Later tonight, agree with previous forecaster that another MCS will track mainly across the northern zones. 18z GFS and HRRR strongly suggest this evolution, as such increased pops into the likely/definite category north of Dodge City. Primary threat through tonight will be excessive rainfall and localized flooding, with an exceptionally moist atmosphere with precipitable water ranging from 1.6 inches NW to 1.8 inches SE as of 5 pm mesoanalysis. Will need to consider a flash flood watch over the next few hours. && .SHORT TERM...(This evening through Saturday) Issued at 249 PM CDT Fri Jul 1 2016 A stronger upper level shortwave trough will move from Four Corners region and into western Kansas tonight. Another MCS (Mesoscale Convective Complex) will likely move out of Colorado and and across much of western Kansas tonight with several upper level waves. Current models however forecast the best QPF and best heavy rain chances north of Dodge City with the area from around Syracuse to near Garden City and LaCrosse and north. Will graduate rainfall chances with that in mind. Severe chances look minimal tonight with maybe some small hail and strong winds to 40 to 50 mph. Very heavy rainfall is expected wherever the MCS tracks with precipitable water values from 1.5 to near 2 inches. Lows tonight will range in the mid to upper 60s. For Saturday, the strong shortwave will continue to move across western Kansas with an attendant cold front. The cold front is forecast to be near Hays to Dodge City and Meade by mid afternoon with the best chances for storms near and east of the front. Strong to severe storms are possible mainly along and east of the cold front with 2000 to 3000 J/kg CAPE and strong mid level shear. Highs will be around 90 east of the front and low to mid 80s west. .LONG TERM...(Saturday night through Friday) Issued at 307 PM CDT Fri Jul 1 2016 For Saturday night, a cold front will continue to move east into central Kansas with lingering strong to severe thunderstorms mainly east of Dodge City into parts of south central Kansas. Then for Sunday into next Friday, a mainly dry period is forecast with a warming trend. Highs warm from the 80s Sunday and around 90 for Monday, the 4th of July, into the mid to upper 90s from Tuesday into next Friday, as warmer upper level ridging builds into the Central Plains. Overnight lows will gradually warm also from 60s into the 70s. && .AVIATION...(For the 06Z TAFS through 06Z Saturday night) Issued at 1206 AM CDT Sat Jul 2 2016 Another cluster of thunderstorms will move across western Kansas early this morning bringing MVFR to IFR conditions to the TAF sites. These storms should move away from the TAF sites by sunrise with VFR conditions for the remainder of the morning into the early afternoon. Another round of thunderstorms is possible again tomorrow evening into the overnight period. Winds will generally start out from the southeast at less than 10 knots shifting to more of a southerly direction after sunrise into the afternoon hours. The only exception to this will be around the thunderstorms this morning where gusty winds will be found. && .PRELIMINARY POINT TEMPS/POPS... DDC 68 85 63 82 / 60 60 70 20 GCK 67 84 61 83 / 80 70 70 10 EHA 65 86 64 87 / 80 60 70 10 LBL 70 88 64 85 / 60 50 70 20 HYS 64 81 61 78 / 90 70 70 20 P28 70 90 69 84 / 40 40 90 30 && .DDC Watches/Warnings/Advisories... Flash Flood Watch until 7 AM CDT /6 AM MDT/ this morning for KSZ043-044-061>063-074-075. && $$ UPDATE...Turner SHORT TERM...Kruse LONG TERM...Kruse AVIATION...Hovorka_42
AREA FORECAST DISCUSSION
National Weather Service Topeka KS
1134 PM CDT FRI JUL 1 2016 ...Update to aviation forecast discussion... .SHORT TERM...(This Evening through Saturday) Issued at 344 PM CDT FRI JUL 1 2016 This afternoon a deep mid-level trough was stretched across the eastern U.S. with surface high pressure situated west of the trough across the Northern and Central Plains. This west-northwesterly flow aloft combined with low/mid cloud cover supported cooler conditions this afternoon with highs topping out in the low/mid 80s. Drier conditions from the surface high were noted across northeast Kansas where dewpoint temperatures dropped into the 40s with dewpoints in the 50s to near 60 degrees elsewhere. With these drier conditions in place, the onset of precipitation will be slower than originally expected as it will take longer to overcome the drier air and for the atmospheric profile to become more deeply saturated. As a result, have lowered PoPs for eastern Kansas late afternoon into this evening. There actually is still model uncertainty with the eastward progression of precipitation tonight into Saturday morning as some models are showing the better lift holding off until overnight across north central to east central Kansas as the low- level jet begins to increase over the area. The larger-scale models still show showers and thunderstorms overspreading the entire forecast area overnight, while the early afternoon model runs of the HRRR and RAP suggest that precipitation may not even advance into northeast Kansas overnight. If this slower solution pans out, then PoPs are too high across eastern Kansas for overnight tonight. However, expect moderate to heavy rainfall rates overnight into Saturday morning with any precipitation that develops as an embedded shortwave lifts northeastward over the area. Model soundings show a deep saturation layer developing with PWAT values upwards of around 2 inches. As a result, rainfall amounts of 1 to 1.5 inches will be possible across portions of north central, central, and east central Kansas by Saturday morning. While instability will be limited through tonight, 0-6km bulk shear values may be upwards of 40-50kts across north central Kansas, so cannot rule out the potential for a few strong storms tonight with gusty winds and hail being the primary hazards. Morning showers and thunderstorms will lift to the northeast as the first embedded shortwave exits the area and a surface warm front and inverted surface trough lift into east central Kansas by early afternoon. Models show the inverted surface trough becoming more north-south oriented during the afternoon hours, and this boundary should provide sufficient lift to support additional widespread showers and storms across north central and far northeast Kansas by mid to late afternoon. Model soundings show a deep saturation layer in place with this second round of storms, with PWAT values rising into the 2 to 2.5 inch range so expect increasing rainfall rates over north central Kansas during the mid/late afternoon hours. If we are able to see some breaks in the cloud cover between the morning and afternoon rounds of precipitation, conditions may destabilize enough to increase the concerns for strong to severe storms as 40- 50kts of 0-6km shear should still be in place. With a few rounds of moderate to heavy rainfall possible, a Flash Flood Watch remains in effect beginning tonight across the entire outlook area. As for temperatures, with the warm front lifting into east central Kansas Saturday afternoon, a decent spread in afternoon temperatures is likely. There is still some uncertainty with where across east central Kansas this temperature gradient will be, but the current forecast has high temperatures ranging from near 70 degrees in far northeast Kansas to the mid/upper 80s across central and east central Kansas. .LONG TERM...(Saturday Night through Friday) Issued at 344 PM CDT FRI JUL 1 2016 The upper trough over the southwest US is forecast to slowly move east into the Central Plains on Saturday and then into the Missouri Valley Saturday night. The upper trough should be strong enough to produce a surface wave along the stalled frontal boundary across southern Kansas Saturday afternoon. The upper trough and associated surface wave moves through the area by Sunday morning. The 12z NAM was faster with the system compared to the 12z GFS/ECMWF. The slower movement appears to be associated with a piece of shortwave energy moving into southern plains Sunday. In all cases, there is a high probability of a heavy rainfall event over northeast Kansas Saturday night. Low-level warm advection over surface boundary, synoptic scale UVV which should have a very moist airmass in place by that point to work with with PWAT values around 2 inches. The convective resolving models (ARW and NMM)produce thunderstorms over the forecast area Saturday night. The 12z NAM/GFS/ECMWF all produce significant pcpn over the area, although their maximum amounts are north of the area closer to the apparent 850 mb warm front. This decreases overall confidence somewhat, but enough confidence remains for high pops and heavy rain over the forecast area. The lingering shortwave energy on Sunday supports keep pops in over the east. Will end the flash flood watch at 12z Sunday morning over the western counties which by then will have very low chances of heavy precipitation. Surface high pressure will be over eastern Kansas on Independence Day which should result in dry weather and below normal temperatures. The 12z GFS is more bullish on building the upper ridge into the Central Plains compared to the 12z ECMWF. The GFS certainly looks drier and hotter Tue-Fri next week. Will go with a compromise at this point with very warm temperatures returning with a chance of thunderstorms due to warm advection Tuesday night. Thunderstorm chances return late in the forecast as a weak boundary moves into the area. && .AVIATION...(For the 06Z TAFS through 06Z Saturday Night) Issued at 1134 PM CDT FRI JUL 1 2016 Main concern for this forecast will be convection timing and duration at the terminals. Complex of tsra in western and central KS should move into the MHK area around 08Z and TOP and FOE in the 09Z-10Z period. Expect tsra to continue in local area through 17Z then diminish before increasing chances once again after 01Z Sun. Cigs vfr and vsbys will vary from vfr to mvfr or ifr at times through the period. Expect brief cigs of mvfr with some of the storms. WInds east around 10 kts or less through the period. && .TOP Watches/Warnings/Advisories... Flash Flood Watch through Sunday evening for KSZ024-026-038>040- 054>056-058-059. Flash Flood Watch through Sunday morning for KSZ008>012-020>023- 034>037. && $$ SHORT TERM...Hennecke LONG TERM...Johnson AVIATION...53 Southeast Alaska Forecast Discussion...Corrected National Weather Service Juneau AK 608 AM AKDT SAT JUL 2 2016 .SHORT TERM...The flood warning for the Mendenhall Lake and River has been cancelled early this morning. See the hydrology section below and the flood warning cancellation statement for additional information. Main weather feature over the next 24 hours will be a compact low pressure system tracking northeast across the northern portion of Haida Gwaii around midday before weakening and moving into British Columbia late tonight. This system is located in the left exit region of a 100 kt upper level jet which will aid in deepening it to around 1000 mb as it approaches Haida Gwaii. It rapidly loses jet support thereafter and will quickly weaken as a result. Aside from the far southern panhandle, the remainder of Southeast Alaska will transition to a weak flow regime. The effects of the compact low will be twofold. It will bring a period of enhanced lift and moderate to occasionally heavy rain through this afternoon for the southern panhandle. Additionally, a strong southeasterly low level jet with 925 mb winds of around 50 kt will increase winds over the far southern panhandle. However, with the track of the system the strongest winds are expected to remain over Dixon Entrance and south of the panhandle. For the northern panhandle, this low will act to shift flow to the east-southeast leading to diminishing rainfall chances through the day. Some peaks of blue sky and sun will even be possible across the northern half this afternoon and evening. Lingering gusty winds this morning associated with a weakening low near Cape Fairweather will also diminish through the morning with a weak pressure gradient and generally light winds in place later this afternoon and into tonight. Used the 06z NAM/GFS for updates to the short term forecast based upon good agreement on track and strength of low pressure system moving into the far southeast gulf. .LONG TERM...The low with the upper level support for the Saturday low over the Dixon Entrance region moves into British Columbia Sunday and as a result the main rain band will be pulling inland across the southern panhandle as well. A weak surface ridge over the eastern gulf will be displaced eastward across the panhandle. Meanwhile, a weak negatively tilted trough associated with a small weak low near Middleton Island Saturday night will stall along the coast of Southeast Alaska. Another weak low will move east across the western Gulf of Alaska, and a more organized low for mid next week. Aloft the main pattern is general westerly flow across the north Pacific and Gulf of Alaska. This has been the trend for the end of the week into the first half of next week so minimal changes were made. Kept the mostly cloudy and low chance level POP`s for rain. Wind should be 20 kt or less for the next several days. Confidence will be average through the mid to later parts of the forecast. The minor adjustments made to the forecast package was based on a NAM/GFS blend while the later periods were based on the WPC guidance. && .HYDROLOGY...Suicide Basin emptied on Friday afternoon with Mendenhall Lake cresting at 11.99 feet on Friday evening. This broke the previous record high crest of 11.85 feet in 2014. Water levels have receded rapidly overnight and will continue to do so through the weekend. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ036-041. Small Craft Advisory due to Seas for PKZ042-043. && $$ TPS/Bezenek Visit us at http://www.weather.gov/Juneau
Southeast Alaska Forecast Discussion National Weather Service Juneau AK 536 AM AKDT SAT JUL 2 2016 .SHORT TERM...The flood warning for the Mendenhall Lake and River has been cancelled early this morning. See the hydrology section below and the flood warning cancellation statement for additional information. Main weather feature over the next 24 hours will be a compact low pressure system tracking northeast across the northern portion of Haida Gwaii around midday before weakening and moving into British Columbia late tonight. This system is located in the left exit region of a 100 kt upper level jet which will aid in deepening it to around 1000 mb as it approaches Haida Gwaii. It rapidly loses jet support thereafter and will quickly weaken as a result. Aside from the far southern panhandle, the remainder of Southeast Alaska will transition to a weak flow regime. The effects of the compact low will be twofold. It will bring a period of enhanced lift and moderate to occasionally heavy rain through this afternoon for the southern panhandle. Additionally, a strong southeasterly low level jet with 925 mb winds of around 50 kt will increase winds over the far southern panhandle. However, with the track of the system the strongest winds are expected to remain over Dixon Entrance and south of the panhandle. For the northern panhandle, this low will act to shift flow to the east-southeast leading to diminishing rainfall chances through the day. Some peaks of blue sky and sun will even be possible across the northern half this afternoon and evening. Lingering gusty winds this morning associated with a weakening low near Cape Fairweather will also diminish through the morning with a weak pressure gradient and generally light winds in place later this afternoon and into tonight. Used the 06z NAM/GFS for updates to the short term forecast based upon good agreement on track and strength of low pressure system moving into the far southeast gulf. .LONG TERM...The low with the upper level support for the Saturday low over the Dixon Entrance region moves into British Columbia Sunday and as a result the main rain band will be pulling inland across the southern panhandle as well. A weak surface ridge over the eastern gulf will be displaced eastward across the panhandle. Meanwhile, a weak negatively tilted trough associated with a small weak low near Middleton Island Saturday night will stall along the coast of Southeast Alaska. Another weak low will move east across the western Gulf of Alaska, and more organized low for mid next week. Aloft the main pattern is general westerly flow pattern across the north Pacific and Gulf of Alaska. This has been the trend for the end of the week into the first half of next week so minimal changes were made. Kept the mostly cloudy and Low chance level PoP`s for rain. Wind should be 20 kt or less for the next several days. Confidence will be average through the mid to later parts of the forecast. the Minor adjustments made too the forecast package was based on a NAM/GFS blend while the later periods were based on the WPC guidance. && .HYDROLOGY...Suicide Basin emptied on Friday afternoon with Mendenhall Lake cresting at 11.99 feet on Friday evening. This broke the previous record high crest of 11.85 feet in 2014. Water levels have receded rapidly overnight and will continue to do so through the weekend. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ036-041. Small Craft Advisory due to Seas for PKZ042-043. && $$ TPS/Bezenek Visit us at http://www.weather.gov/Juneau
Southeast Alaska Forecast Discussion National Weather Service Juneau AK 536 AM AKDT SAT JUL 2 2016 .SHORT TERM...The flood warning for the Mendenhall Lake and River has been cancelled early this morning. See the hydrology section below and the flood warning cancellation statement for additional information. Main weather feature over the next 24 hours will be a compact low pressure system tracking northeast across the northern portion of Haida Gwaii around midday before weakening and moving into British Columbia late tonight. This system is located in the left exit region of a 100 kt upper level jet which will aid in deepening it to around 1000 mb as it approaches Haida Gwaii. It rapidly loses jet support thereafter and will quickly weaken as a result. Aside from the far southern panhandle, the remainder of Southeast Alaska will transition to a weak flow regime. The effects of the compact low will be twofold. It will bring a period of enhanced lift and moderate to occasionally heavy rain through this afternoon for the southern panhandle. Additionally, a strong southeasterly low level jet with 925 mb winds of around 50 kt will increase winds over the far southern panhandle. However, with the track of the system the strongest winds are expected to remain over Dixon Entrance and south of the panhandle. For the northern panhandle, this low will act to shift flow to the east-southeast leading to diminishing rainfall chances through the day. Some peaks of blue sky and sun will even be possible across the northern half this afternoon and evening. Lingering gusty winds this morning associated with a weakening low near Cape Fairweather will also diminish through the morning with a weak pressure gradient and generally light winds in place later this afternoon and into tonight. Used the 06z NAM/GFS for updates to the short term forecast based upon good agreement on track and strength of low pressure system moving into the far southeast gulf. .LONG TERM...The low with the upper level support for the Saturday low over the Dixon Entrance region moves into British Columbia Sunday and as a result the main rain band will be pulling inland across the southern panhandle as well. A weak surface ridge over the eastern gulf will be displaced eastward across the panhandle. Meanwhile, a weak negatively tilted trough associated with a small weak low near Middleton Island Saturday night will stall along the coast of Southeast Alaska. Another weak low will move east across the western Gulf of Alaska, and more organized low for mid next week. Aloft the main pattern is general westerly flow pattern across the north Pacific and Gulf of Alaska. This has been the trend for the end of the week into the first half of next week so minimal changes were made. Kept the mostly cloudy and Low chance level PoP`s for rain. Wind should be 20 kt or less for the next several days. Confidence will be average through the mid to later parts of the forecast. the Minor adjustments made too the forecast package was based on a NAM/GFS blend while the later periods were based on the WPC guidance. && .HYDROLOGY...Suicide Basin emptied on Friday afternoon with Mendenhall Lake cresting at 11.99 feet on Friday evening. This broke the previous record high crest of 11.85 feet in 2014. Water levels have receded rapidly overnight and will continue to do so through the weekend. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ036-041. Small Craft Advisory due to Seas for PKZ042-043. && $$ TPS/Bezenek Visit us at http://www.weather.gov/Juneau
  [top] Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 500 AM AKDT SAT JUL 2 2016 .ANALYSIS AND UPPER LEVELS... Upper level lows remain over the western Bering and the southeastern Gulf of Ak this morning, with a weak ridge along the west coast of the mainland. At the surface, a low is near Amchitka and a second is headed to Haida Gwaii. A weak ridge of high pressure is draped from the northwest Bering to Cold Bay, and a decaying front parallels the ridge slightly to its west. the thermal trough/theta-e ridge remains along the northern and western flanks of the Alaska and Aleutian ranges. && .MODEL DISCUSSION... Models are in general agreement that the Gulf upper and surface low complex are headed into southeast Ak today. The low will elongate and split with the main portion headed into British Columbia, and a smaller low drifting just east of the Alcan until dissipating early next week. An associated extremely weak surface low will drift in the northern Gulf through the period. As the upper low exits to the southeast it will send a few waves through the thermal trough today and Sun before the pattern shifts and the easterly waves come to an end. This will be caused by an upper trough digging south through the Bering Sun and Mon. In the west, the decaying front will be stretched as the Aleutian low weakens into a broad trough. The moisture rich remnants of the system will then interact with the diving trough later on Mon. The forecasts utilized some GFS and Nam to capture wave details. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2...Sat and Sun)... The strong disturbance bringing moderate to heavy rains to parts of Southwest Alaska will pivot in place over lower Cook Inlet later today and then significantly weaken. The associated rains with this system will impact Kodiak Island this morning, and then diminish in intensity over the Barren Islands, just clipping the southern Kachemak Bay region. Meanwhile...the rest of the area will remain in very light flow with generally moist and marginally unstable conditions. With all the recent rainfall...many places could see some patchy fog or low stratus develop overnight, but this should dissipate relatively quickly on Saturday as some sun breaks through. Showers should develop along the mountains in the afternoon, but with weak steering flow, we don`t expect many of them to make it into valleys. The best instability remains farther north over the Alaska Range and parts of the Talkeetna Mountains as well as the northern half of the Copper River Basin, so isolated thunderstorms are expected in these locations. Increasing southwesterly flow and an approaching upper disturbance Sunday into Sunday night will mean a slow stabilizing trend as we approach the Independence Day holiday Monday. Expect more robust shower activity over the Kenai Range Sunday afternoon and evening, and as 850-mb and 700-mb southwesterly flow increases, we cannot at this time rule out at least some chance of light rain pushing north off of the mountains into parts of Anchorage and the Matanuska Valley late Sunday night into early Monday. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... The cloudy rainy pattern over the mainland will continue the next two days with decreasing coverage each day. Steady rain will shift from the Kuskokwim Valley southward into Greater Bristol Bay during the afternoon. The Kuskokwim Delta will be right on the edge of the disturbance over the Eastern Mainland, and should stay mostly shower-free save for areas south and east of Bethel in the afternoon/evening hours. Overnight into Sunday most of the rain will be confined to the higher elevations of the Kuskokwim Valley. The flow pattern changes on Monday in response to a developing trough in the Western Bering Sea, which will result in continued cloudiness and a small chance for light rain. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... The upper level low pressure system over the western Bering continues to weaken. A disturbance within the flow will weaken over the Eastern Aleutians and Alaska Peninsula today as light rain tapers off to sprinkles. The large scale trough stays in the area continuing a small chance for light rain before a stronger disturbance drops into the northwestern Bering late Sunday night. && .LONG TERM FORECAST (Days 3 through 7)... For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...DS SOUTHCENTRAL ALASKA...CC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML LONG TERM...TP/DS
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 500 AM AKDT SAT JUL 2 2016 .ANALYSIS AND UPPER LEVELS... Upper level lows remain over the western Bering and the southeastern Gulf of Ak this morning, with a weak ridge along the west coast of the mainland. At the surface, a low is near Amchitka and a second is headed to Haida Gwaii. A weak ridge of high pressure is draped from the northwest Bering to Cold Bay, and a decaying front parallels the ridge slightly to its west. the thermal trough/theta-e ridge remains along the northern and western flanks of the Alaska and Aleutian ranges. && .MODEL DISCUSSION... Models are in general agreement that the Gulf upper and surface low complex are headed into southeast Ak today. The low will elongate and split with the main portion headed into British Columbia, and a smaller low drifting just east of the Alcan until dissipating early next week. An associated extremely weak surface low will drift in the northern Gulf through the period. As the upper low exits to the southeast it will send a few waves through the thermal trough today and Sun before the pattern shifts and the easterly waves come to an end. This will be caused by an upper trough digging south through the Bering Sun and Mon. In the west, the decaying front will be stretched as the Aleutian low weakens into a broad trough. The moisture rich remnants of the system will then interact with the diving trough later on Mon. The forecasts utilized some GFS and Nam to capture wave details. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2...Sat and Sun)... The strong disturbance bringing moderate to heavy rains to parts of Southwest Alaska will pivot in place over lower Cook Inlet later today and then significantly weaken. The associated rains with this system will impact Kodiak Island this morning, and then diminish in intensity over the Barren Islands, just clipping the southern Kachemak Bay region. Meanwhile...the rest of the area will remain in very light flow with generally moist and marginally unstable conditions. With all the recent rainfall...many places could see some patchy fog or low stratus develop overnight, but this should dissipate relatively quickly on Saturday as some sun breaks through. Showers should develop along the mountains in the afternoon, but with weak steering flow, we don`t expect many of them to make it into valleys. The best instability remains farther north over the Alaska Range and parts of the Talkeetna Mountains as well as the northern half of the Copper River Basin, so isolated thunderstorms are expected in these locations. Increasing southwesterly flow and an approaching upper disturbance Sunday into Sunday night will mean a slow stabilizing trend as we approach the Independence Day holiday Monday. Expect more robust shower activity over the Kenai Range Sunday afternoon and evening, and as 850-mb and 700-mb southwesterly flow increases, we cannot at this time rule out at least some chance of light rain pushing north off of the mountains into parts of Anchorage and the Matanuska Valley late Sunday night into early Monday. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... The cloudy rainy pattern over the mainland will continue the next two days with decreasing coverage each day. Steady rain will shift from the Kuskokwim Valley southward into Greater Bristol Bay during the afternoon. The Kuskokwim Delta will be right on the edge of the disturbance over the Eastern Mainland, and should stay mostly shower-free save for areas south and east of Bethel in the afternoon/evening hours. Overnight into Sunday most of the rain will be confined to the higher elevations of the Kuskokwim Valley. The flow pattern changes on Monday in response to a developing trough in the Western Bering Sea, which will result in continued cloudiness and a small chance for light rain. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... The upper level low pressure system over the western Bering continues to weaken. A disturbance within the flow will weaken over the Eastern Aleutians and Alaska Peninsula today as light rain tapers off to sprinkles. The large scale trough stays in the area continuing a small chance for light rain before a stronger disturbance drops into the northwestern Bering late Sunday night. && .LONG TERM FORECAST (Days 3 through 7)... For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...DS SOUTHCENTRAL ALASKA...CC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML LONG TERM...TP/DS
  [top] Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 419 AM AKDT SAT JUL 2 2016 .DISCUSSION... UPPER AIR... A weak ridge currently extends from St Lawrence Island to the eastern Beaufort Sea then links up to a much stronger ridge over northwest Canada. The Alaskan portion of the ridge will gradually weaken through Saturday night, with the main high pressure aloft remaining over northwestern Canada by Sunday afternoon. A more organized mainly southerly flow pattern aloft will become established over the northern Alaska Mainland by Monday afternoon. A weak upper low will develop over the extreme southern Yukon Territory this afternoon, remain nearly stationary through Sunday night, then weakening into a trough lifting northward across the eastern Alaska interior Monday through Tuesday. A weak short wave trough along the Alcan border south of the Brooks Range will move to the southeast interior by this afternoon, weakening into a weak upper low near the middle Tanana Valley by this evening. This feature will weaken into a weak trough over Denali by Sunday afternoon, then dissipate Sunday night. A strong short wave trough extending from 80N/180W to the New Siberian Islands will swing eastward around a strong upper low over the north polar region. By late tonight the short wave will extend from 80N/160E to Wrangel Island and southward into the Russian mainland. The trough will then remain stationary through Sunday night while deepening into an elongated low extending from Wrangel Island to south of the Gulf of Anadyr. SURFACE... A 1002 mb low centered about 100 miles east of Northway will weaken to a 1002 mb low centered 100 miles east of Fort Yukon by late tonight. A 1002 mb low will develop 50 miles west of Bettles this afternoon with a weak thermal trough extending eastward into the upper Yukon Valley. This thermal trough will gradually intensify through Sunday and weaken to the northern Brooks Range by Monday afternoon, with a main 1006 mb thermal low over the central Brooks Range. A weak high pressure ridge will expand eastward across the Beaufort Sea tonight, with a 1014 mb high forming 300 miles north of Deadhorse by Sunday evening. The high will build to 1020 mb by Monday evening as it moves northeastward to Prince Patrick Island in the Canadian archipelago. A 1020 mb high centered west of the New Siberian Islands will weaken to a 1015 mb high centered near Wrangel Island by Monday morning. INTERIOR... Today and this evening..Showers and isolated thunderstorms are expected over most areas. Convective activity could be enhanced by a weak short wave trough along the Alcan border. The greatest instability this afternoon and evening will be over the western interior. Showers likely continuing into the late night hours. Sunday and Sunday evening...Showers and isolated thunderstorms continuing over the central and eastern interior. Scattered showers and isolated thunderstorms also possible in the upper Kuskokwim Valley. Showers likely continuing into the late night hours. Monday and Monday evening...Showers and isolated thunderstorms continuing over almost all of the central and eastern interior, and in extreme southern parts of the western interior. The most instability is expected to be over the northeastern interior, GFS indicating areas of 800-1000 J/kg surface CAPE with surface lifted index as low as -3. There is potential for the thunderstorm activity to be scattered in parts of the northeast interior, but at this time we will stay with isolated activity. Future model runs will need to be monitored. A weakening short wave trough moving northward across the eastern interior could enhance thunderstorm activity as well as triggering extensive showers. Showers likely continuing into the late night hours. WEST COAST... No significant weather expected through Monday. Patchy coastal fog in some areas. ARCTIC SLOPE AND BROOKS RANGE... Warm temperatures continuing through Monday...especially in the interior where high temperatures will reach 70 or higher in many areas. Patchy fog possible along the coast during the late night and early morning hours. Scattered rain showers over the northeastern Brooks Range Sunday night and Monday, with isolated thunderstorms Monday afternoon. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Minimum RH expected to be 40% or higher over most interior areas today. Warmer temperatures over the northern and northeastern interior Sunday and Monday. Minimum humidities are expected to be lower, but still above 30-35 percent. Forecast CAPE and lifted index numbers indicate the possibility of scattered thunderstorms in parts of the northeastern interior Monday. We are going with isolated thunderstorms on this mornings forecast package, but forecast CAPE and lifted index on future model runs will need to be monitored. && .HYDROLOGY... Given the high precipitable water values (1 to 1.2 inches) in parts of the central and eastern interior through Tuesday, there is potential for locally heavy showers which, if they occur in mountainous terrain, could cause small stream flood issues. Rain gage data will need to be closely monitored. && .AFG WATCHES/WARNINGS/ADVISORIES... None. && $$ RF JUL 16
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 441 PM AKDT FRI JUL 1 2016 .ANALYSIS AND UPPER LEVELS... The upper level low remains over the Gulf of Alaska, but is beginning to show signs of moving east. The strong short-wave system on the northwest side of the low that provided last nights rainfall to south central Alaska is now in southwest Alaska. There is an upper level low over the southwest Bering Sea as well as the western and central Aleutians. This low has stalled and is continuing to weaken. A weather front associated with this low stretches from about Nikolski northwestward across the Bering Sea. A ridge of high pressure separates these two low, with the "col" over the far eastern Bering. && .MODEL DISCUSSION... The numerical models are in reasonable agreement on the over-all pattern. There continue to be some differences in the timing, location, and strength of various short-waves surrounding the Gulf low. There are also some minor differences in the handling of precipitation, especially in regards to convection. Therefore the forecast confidence is slightly below normal. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2...Sat and Sun)... Afternoon mountain showers and diurnal sea breezes will be the story for the weekend. The easterly wave that brought a third to an inch and half of rain across Southcentral has cleared through most of the area. The Alaska Range has slowed its westward progress keeping some rain falling over Kachemak Bay. It will pivot through this corridor on Sat bringing rain to parts of Kodiak Island later tonight through the Sat morning hours. Meanwhile...the rest of the area will remain in very light flow with generally moist and unstable conditions. With all the recent rainfall...many places could see some patchy fog or low stratus develop overnight. But this should dissipate relatively quickly on Saturday as some sun breaks through. Showers should develop along the mountains in the afternoon, but with weak steering flow, we don`t expect many of them to make it into valleys. The best instability remains farther north over the Alaska Range and parts of the Talkeetna Mountains, so can`t rule out an isolated thunderstorm developing on those higher peaks. Sun looks very similar to Sat with minimal change to the pattern. The leftover band of rain near Kodiak should move off into the Gulf making for drying conditions there. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... The Gulf low that has been relatively stationary the last couple of days will finally push off to the east tonight. This will change the easterly flow over the area to be more northerly which will help to diminish showers over the area. The majority of the rain remaining by the beginning of next week will be in the more eastern parts of Southwest Alaska like the Alaska and Aleutian Ranges. Even though the main upper level low is departing there are still more shortwaves moving through the area with the strongest one coming through this evening. It will track south from the Kuskokwim Valley towards Bristol Bay and will help to initiate thunderstorms in the area. There will also be enough instability over the Kuskokwim Valley for possible afternoon thunderstorms Saturday and Sunday. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... The broad area of low pressure over the Western Aleutians will track slowly east over the weekend. It looks to bring light rain to the Aleutians with some making it to the Pribilof Islands on Saturday. By the beginning of next week the broad upper level low will be absorbed into a broad trough extending across the Bering from the north. This trough will keep light rain over the Bering and Aleutians. && .LONG TERM FORECAST (Days 3 through 7)... The upper level pattern will begin to shift by the end of this weekend to a more stable pattern, as the upper low shifts further east and weak high pressure aloft builds in from the west. Thus, with everything being weak, any precipitation that develops Sunday over southern mainland Alaska will be mostly scattered and weak. The persistence of a mid-level unstable layer over much of the area will result in some diurnal showers mainly along the mountains. For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...BL SOUTHCENTRAL ALASKA...MO SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK LONG TERM...TP
Southeast Alaska Forecast Discussion National Weather Service Juneau AK 324 PM AKDT FRI JUL 1 2016 .SHORT TERM...A low just west of Sitka this afternoon continues to track north along the outer coast. Visible and WV satellite imagery is clearly depicting the circulation, but it is not nearly as evident in IR imagery. Radar has been showing banding in the returns, but the total system is slightly stronger than originally expected and had produced 30 kts of wind in Clarence Strait earlier today. Morning model runs still showing some divergence on the low center. With the system so close to the outer coast, minor differences in location, track, and intensity can have significant impacts in the forecast. That said, opted for the NAM for updates to pressure and winds today. Resulting changes primarily affect the winds over the eastern gulf and coastal locations north of Cape Decision. On the inside, result was to increase winds speeds a bit, so the afternoon forecast features small craft advisories for several of the inner channels. Clarence Strait is expected to continue at high end small craft intensity through the evening before relaxing. A low approaching the Dixon Entrance from the southwest tomorrow will produce another round of small craft winds out of the east tomorrow afternoon, but these winds will be mostly over southern areas near the Dixon Entrance. Small craft southerlies will get into the ocean entrances of Chatham Strait and Sumner Strait early this evening but should diminish to 15 kts or so by tomorrow morning. Also expect small craft winds out of the east over eastern portions of Sumner and southeasterlies to 25 kts along Frederick Sound south of Cape Fanshaw. Later tonight, max winds on the inside will shift north to include Stephens passage north of Taku inlet, the northern portions of Chatham Strait, and much of Icy Strait. Finally, easterly Small Craft winds to 30 kts from late this evening through tomorrow afternoon are forecast for Cross Sound. Small craft winds on the outside will progress from south to north as well, ending late morning as the low weakens and fills vicinity of Cape Fairweather. POP forecast from last night still looks good, so no changes there. Did update QPF using a blend of Canadian REG and NAMDNG. Overall forecast confidence is average to below average due to uncertainties in how inner channel winds will respond to the low off the coast. .LONG TERM...The low passing through Dixon Entrance Saturday night will keep showers largely confined to the southern panhandle. An upper level low shifts south Saturday night then looks to settle over central BC Sunday. This will also help to clear away showers initially over the north, but then once its in Canada may cause clouds and some showers to move in from the east. For this reason chance/slight chance of showers remain in the forecast over the weekend. Weak ridging will develop over the gulf starting Monday, or a better way to describe it, zonal onshore flow. This leads to a chance of rain in the forecast, or at least a bit more cloud cover. There are some indications that a marine layer could develop over the gulf under the ridge, this will be monitored over the next couple days. If an inversion develops or there is a low cloud deck that would be of concern for Monday night activities along the outer coast. Adjusted temps up slightly through the extended forecast as both base models and bias corrected models were warmer. Thinking that sunny breaks in the clouds will allow for more seasonable highs in the mid 60s. Used an ensemble approach for updates today. Model agreement on pressure was good through the mid range then diverged day 6, used more WPC guidance for later periods. Model differences on the POP forecast were still fairly high over the holiday, so still lower confidence in that part of the forecast. && .HYDROLOGY...Early afternoon indications are that Suicide Basin may have emptied out. The lake, however, will continue to rise through the evening, with a forecast crest of at or near 12 feet later tonight. See the flood warning issued by NWS Juneau for details and be careful and vigilant around flood waters. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ021-022-031>036-041>043. && $$ Fritsch/Ferrin Visit us at http://www.weather.gov/Juneau
Southeast Alaska Forecast Discussion National Weather Service Juneau AK 324 PM AKDT FRI JUL 1 2016 .SHORT TERM...A low just west of Sitka this afternoon continues to track north along the outer coast. Visible and WV satellite imagery is clearly depicting the circulation, but it is not nearly as evident in IR imagery. Radar has been showing banding in the returns, but the total system is slightly stronger than originally expected and had produced 30 kts of wind in Clarence Strait earlier today. Morning model runs still showing some divergence on the low center. With the system so close to the outer coast, minor differences in location, track, and intensity can have significant impacts in the forecast. That said, opted for the NAM for updates to pressure and winds today. Resulting changes primarily affect the winds over the eastern gulf and coastal locations north of Cape Decision. On the inside, result was to increase winds speeds a bit, so the afternoon forecast features small craft advisories for several of the inner channels. Clarence Strait is expected to continue at high end small craft intensity through the evening before relaxing. A low approaching the Dixon Entrance from the southwest tomorrow will produce another round of small craft winds out of the east tomorrow afternoon, but these winds will be mostly over southern areas near the Dixon Entrance. Small craft southerlies will get into the ocean entrances of Chatham Strait and Sumner Strait early this evening but should diminish to 15 kts or so by tomorrow morning. Also expect small craft winds out of the east over eastern portions of Sumner and southeasterlies to 25 kts along Frederick Sound south of Cape Fanshaw. Later tonight, max winds on the inside will shift north to include Stephens passage north of Taku inlet, the northern portions of Chatham Strait, and much of Icy Strait. Finally, easterly Small Craft winds to 30 kts from late this evening through tomorrow afternoon are forecast for Cross Sound. Small craft winds on the outside will progress from south to north as well, ending late morning as the low weakens and fills vicinity of Cape Fairweather. POP forecast from last night still looks good, so no changes there. Did update QPF using a blend of Canadian REG and NAMDNG. Overall forecast confidence is average to below average due to uncertainties in how inner channel winds will respond to the low off the coast. .LONG TERM...The low passing through Dixon Entrance Saturday night will keep showers largely confined to the southern panhandle. An upper level low shifts south Saturday night then looks to settle over central BC Sunday. This will also help to clear away showers initially over the north, but then once its in Canada may cause clouds and some showers to move in from the east. For this reason chance/slight chance of showers remain in the forecast over the weekend. Weak ridging will develop over the gulf starting Monday, or a better way to describe it, zonal onshore flow. This leads to a chance of rain in the forecast, or at least a bit more cloud cover. There are some indications that a marine layer could develop over the gulf under the ridge, this will be monitored over the next couple days. If an inversion develops or there is a low cloud deck that would be of concern for Monday night activities along the outer coast. Adjusted temps up slightly through the extended forecast as both base models and bias corrected models were warmer. Thinking that sunny breaks in the clouds will allow for more seasonable highs in the mid 60s. Used an ensemble approach for updates today. Model agreement on pressure was good through the mid range then diverged day 6, used more WPC guidance for later periods. Model differences on the POP forecast were still fairly high over the holiday, so still lower confidence in that part of the forecast. && .HYDROLOGY...Early afternoon indications are that Suicide Basin may have emptied out. The lake, however, will continue to rise through the evening, with a forecast crest of at or near 12 feet later tonight. See the flood warning issued by NWS Juneau for details and be careful and vigilant around flood waters. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ021-022-031>036-041>043. && $$ Fritsch/Ferrin Visit us at http://www.weather.gov/Juneau
Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 303 PM AKDT FRI JUL 1 2016 .SYNOPSIS... Aloft... A ridge stretching east to west across northern Alaska will persist through the weekend then retreat east in NW Canada next week as a trough develops over the Bering Sea. A low aloft in the Gulf of Alaska will move over SE Alaska Sat and then move slowly east. A series of short wave troughs rotating around this low will move west across Interior Alaska bringing bands of showers and isolated to scattered thunderstorms to the eastern and southern Interior through the weekend. A strong short wave that now lies from Denali to Livengood to Old Crow will move to McGrath to Tanana to Arctic Village by 4am Sat...and then weaken in place through Sun. There is a wide band of showers NW of this trough that becomes scattered north of the Yukon River. This dropped .10 to .25 inch of rain over the eastern Interior south of Circle with up to .50 inch in the hills north of Fox and east of Delta Junction. Expect this to drop another .50 to 1 inch over zones 221 225 and 227 through Sat with the heaviest amounts in Denali Park. From .50-1.5 inch of rain has already fallen in Denali Park so this will keep small stream and rivers there high through the weekend and could still cause mud and rock slides. A second and weaker short wave trough near Old Crow will move to Fort Yukon by 4am Sat...to Denali to Livengood by 4pm Sat...and then slowly dissipate through Sun. This will cause scattered showers and scattered PM thunderstorms in eastern zone 216 western 221 and 227 Sat and into Sun. The thunderstorms could have small hail Sat. A third short wave trough over the southern Yukon Territory will move to the ALCAN Border by 4pm Sat and then weaken over the eastern Interior through Sun. This will bring more widespread showers to zones 224 226 Sat into Sun and keep scattered showers and at least isolated thunderstorms going in the remainder of the eastern Interior. There is the potential for hail again Sun and this will need to be watched. A fourth short wave is expected to move to the extreme SE interior Sun night and Mon and could bring heavy rain...but this still has a lot of uncertainty. Surface... An Arctic warm front from Barter Island to Deadhorse will move to Barter Island north by 4am Sat then move north of the coast. Expect fog to reform along this front tonight and then move offshore Sat. A 1022 mb high over the central Bering Sea will weaken slowly through Sun. An Arctic cold front in the western Chukchi Sea will move east to Barrow to Cape Lisburne then west by 4pm Sat...to Deadhorse to a 1007 mb low near Point Hope by 4am Sun...and then quasi- stationary. Fog and a chance of rain will accompany the front. Westerly flow will increase south of the low center and should return widespread fog to the southern Chukchi and north Bering Seas and most of the West Coast of AK by Sat night. && .DISCUSSION... Models are similar on the large scale flow pattern and features but differ some on timing and location of weak short wave troughs moving west across the Interior. Since these weak short wave troughs are the main force driving convection over the interior the location is important. We favor the GFS locations of the short waves and heavy rain through Sat night Sun and then the flow becomes so weak that we can really only deal with short wave location and accompanying rainfall in a probabilistic sense. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Continued wet across southern and eastern Interior with drier and warmer conditions in the northwest Interior. Expect isolated thunderstorms a a few lightning strikes today and Sat...except LAL 3 Sat in eastern Zone 216...western 221 and 227. Sun could see LAL 3 over the eastern Interior but uncertain at this point so left it as LAL 2 for Sun. && .HYDROLOGY... The past 36 hrs saw .10 to .25 inch of rain fall over the eastern Interior south of Circle with up to .50 inch in the hills north of Fox and hills east of Delta Junction...while Denali Park had between .50-1.5 inch. Expect another .50 to 1 inch over zones 221 225 and 227 through Sat with the heaviest amounts in Denali Park. This will keep small stream and rivers in Denali high through the weekend and could cause mud and rock slides through the weekend. There is a potential for heavy rain in zones 224 and 226 SE of Tok Sun night and Mon but still much uncertainty on this. && .AFG WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory for PKZ245. && $$ JB JUL 16
Southeast Alaska Forecast Discussion National Weather Service Juneau AK 533 AM AKDT FRI JUL 1 2016 .SHORT TERM...The biggest story over the next 24 hours is the ongoing glacial dam release from Suicide Basin into Mendenhall Lake and River. This will be covered further in the hydrology section below. As for the weather, the main feature is a 1000 mb low pressure system currently in the southeast gulf which will gradually weaken while moving north to near Cape Fairweather by late tonight. A secondary wave of low pressure will develop southwest of Haida Gwaii late tonight but is expected to remain south of the area. Stratiform rainfall is currently ongoing across the southern half of the panhandle aided by warm air advection in association with the advancing low. This will continue to spread northward through the day reaching the Juneau area this morning and the far northern panhandle this afternoon. Precipitation chances will remain high throughout the next 24 hours across all of Southeast Alaska. Expecting rainfall totals to generally range from one half of an inch to an inch with heaviest amounts over the southern panhandle. This system will enhance winds over the southern half of the area but am only expecting 10 to 20 mph for the land areas and 20-25 kt for the inner channels. Decreased winds across the far northern panhandle as a parallel pressure gradient to Northern Lynn Canal will lead to lighter winds. Used the 06z NAM and Hi-Res model guidance for updates to the short term period. Forecaster confidence is above average. .LONG TERM...Through the weekend, generally a zonal flow pattern in place across the north Pacific aloft. The closed low at 500 mb over the Gulf of Alaska weakens and moves into western Canada Monday while a broad weak ridge aloft forms over the western gulf. Weak to null flow aloft over the northern panhandle will be in place headed into early next week. Long range trend for Southeast Alaska looks to be for a development around mid week to the end of the week over the gulf. A surface low near Cape Fairweather is weakening, while a low moving across the southern gulf along 50N and then curving north across Haida Gwaii on Saturday. This will spread rain into the southern half of the panhandle. Saturday evening the low will move into British Columbia while the low off of Cross Sound dissipates. The surface pattern across the gulf Friday into Saturday becomes west to northwest. The potential for low probability showers from onshore flow will exist along the outer coast Sunday into Monday. With the main flow pattern to the south of the forecast area not expecting a significant weather system for the next few days. && .HYDROLOGY...Suicide Basin has released and a flood warning is in effect for Mendenhall River and Lake until Saturday morning. The current forecast crest of 11.6 feet is close to the previous record value of 11.85 feet set in 2014. As of early this morning, Mendenhall Lake had risen to a stage of 8.5 feet and the rate of rise is steadily increasing as expected. The level in Suicide Basin continues to fall rapidly. Residents near the lake or the river should remain alert and keep track of updates to this event as they are issued by NWS Juneau. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ033>036-041>043. && $$ TPS/Bezenek Visit us at http://www.weather.gov/Juneau
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 447 AM AKDT FRI JUL 1 2016 .ANALYSIS AND UPPER LEVELS... Upper level lows are over the western Bering and the southern Gulf of Ak this morning with the jet remaining well south of the forecast area. At the surface, lows are near Attu and over the eastern Gulf. A ridge of high pressure is over the eastern Bering. The thermal trough/theta-e ridge is draped along the Alaska and Aleutian ranges and is serving as the focus for showers and even a few nocturnal thunderstorms. && .MODEL DISCUSSION... Models remain in agreement that the Gulf upper low will slowly rotate its way into British Columbia by Sun morning. Easterly waves moving along the northern flank of the low will interact with the moisture rich thermal trough/theta-e ridge through the weekend. This may explain what is happening, but these waves are poorly timed in model solutions, so exactly when precipitation initiation and enhancement will occur remains a problem. The forecast utilizes some Nam and GFS in an attempt to pinpoint some of the precipitation events. In the west the surface low will drift and weaken over the western Aleutians through the weekend. A weak associated front will move to the central Aleutians during the same period. Again the Nam and GFS were utilized in the forecast. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... The last of a series of fairly strong short-waves crossing westward across Southcentral Alaska this morning will exit to Southwest Alaska this afternoon bringing an end to widespread showers and rain. However, as the large upper low over the Gulf tracks eastward today and tonight, short-waves tracking across Southwest Alaska will rotate southeastward across Kodiak Island and the western Gulf bringing widespread showers to that region. In the wake of the upper level low the flow across the region will become more and more chaotic, with weak impulses wandering around. This creates a lot of uncertainty in the forecast. Have used a broadbrush approach to the precip forecast for tonight through Saturday night. In this scenario would expect more showers during the afternoon and evening hours focused along the mountains. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... Clouds, rain, and thunderstorms will be the focus for Friday and Saturday. Widespread showers with embedded thunderstorms will encompass the Kuskokwim Valley southward through Greater Bristol Bay today. A lesser chance exists over the Kuskokwim Delta, but afternoon showers and a slight chance for thunder are possible. Nearly the same conditions are on tap for Saturday, however, any thunderstorms will stay confined to the Kuskokwim Valley along the Alaska Range. For the Delta, most of the shower activity will be east of Bethel along the Kilbucks. Winds will be on the lighter side everywhere, and temperatures will be well above average for this time of year. Technically speaking...A large upper level low in the gulf controls the pattern, but the real action is rotating around the circulation in the form of embedded easterly shortwaves. Feeding on the baroclinity from the difference between the cooler gulf airmass and the warmer Interior/Yukon airmass, these waves amplify and provide the forcing for diurnally enhanced showers and thunderstorms. Ridging over the northern portion of the state is breeding warm low level temperatures that will be advected down into the Southwest Mainland, as well as some juicy dewpoints by Alaska standards. These conditions are ripe for frequent lightning over mainly the Kuskokwim Valley and into Bristol Bay today. The upper level energy lingers through the weekend keeping at least showers in the forecast. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... A weakening system aloft over the Western Bering will bring rain today from Shemya through the Central Aleutians, and as far east as the Eastern Aleutians. That system will weaken through the weekend and not produce meaningful precipitation after today. A fairly narrow corridor of dense fog will set up today roughly from Saint Matthew through the Pribilofs and linger through tonight. && .LONG TERM FORECAST (Days 3 through 7)... On Sunday, the upper level pattern looks to grind to a halt from the easterly flow of weak disturbances to a much more chaotic movement. This will be due to the departure of the upper level low towards the Panhandle by Sunday morning, with no larger scale features following it. Thus, with everything being weak, any precipitation that develops Sunday over southern mainland Alaska will be scattered and weak. The persistence of a mid-level unstable layer over much of the area will result in some convection popping up with any showers that develop with enhanced lift, likely from topographic enhancement. For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...DS SOUTHCENTRAL ALASKA...SEB SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML LONG TERM...JW
Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 418 AM AKDT FRI JUL 1 2016 .DISCUSSION... UPPER AIR... A high pressure ridge currently extends from the Chukotsk Peninsula eastward across the Brooks Range into northwestern Canada, with a high center near the Bering Strait. The ridge will gradually transition to a high pressure center which will be pushed gradually eastward through Sunday night as a strong short wave drops southward out of the Russian Arctic Ocean. By late Sunday night the upper level high will be centered near Fort Yukon, with the strong short wave trough extending along 178W across the Chukchi Sea and Bering Sea. A series of weak short wave troughs will move westward across the southern interior through Saturday. A weak short wave trough is now moving westward across the central interior. The next short wave trough is now over the southern Yukon Territory and will move to the Alcan border by Friday morning then fracture into two troughs. The southern piece of the trough will continue to move westward and gradually deepen over the lower Kuskokwim Valley and southeastward Friday evening. The northern piece of the trough will stall out over the eastern interior Friday night and gradually weaken Saturday. SURFACE... A 1007 mb low centered near Northway will deepen to a 1001 mb low about 100 miles east of Northway by this afternoon, then remain nearly stationary through Saturday. A weak thermal trough will develop across the northern interior Saturday. INTERIOR... Areas or bands of showers and thunderstorms associated with the short wave troughs aloft will move westward across the southern interior and the Alaska Range, otherwise there will be isolated to scattered showers and isolated thunderstorms over most areas through the weekend. The heaviest rainfall today will likely be over Denali and the lower Kuskokwim Valley. The heaviest rainfall amounts tonight are expect to be in the lower Kuskokwim valley and in nearby area of the middle Yukon Valley. More showers and isolated thunderstorms are expected over much of the interior Saturday, and over much of the southern and eastern interior Sunday. ARCTIC SLOPE AND BROOKS RANGE... Areas of fog near the coast during the late night and early morning hours, otherwise no significant weather expected through Sunday. Warm temperatures in the interior with highs as high as the low to mid 70s. WEST COAST... No significant weather expected through Sunday. Some coastal areas may see areas of fog. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Some warming is expected in the interior over the weekend...with highs approaching or reaching 80 in some northern interior areas. Minimum humidities could approach 30 percent in the northern interior. Minimum humidities in the southern interior likely to remain at 35 percent or above. && .HYDROLOGY... Additional rainfall amounts of 0.5 to 1 inch are expected in Denali and the lower Kuskokwim Valley today. Northern parts of the Upper Tanana Valley and Fortymile country may see up to 0.5 inch, with local amounts of 0.75 inch possible. Locally heavier amounts will be possible in Denali and the lower Kuskokwim Valley today, but the location of the amounts remains uncertain due to the convective nature of the precipitation. && .AFG WATCHES/WARNINGS/ADVISORIES... Small craft advisory for PKZ245. && $$ RF JUN 16
Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 418 AM AKDT FRI JUL 1 2016 .DISCUSSION... UPPER AIR... A high pressure ridge currently extends from the Chukotsk Peninsula eastward across the Brooks Range into northwestern Canada, with a high center near the Bering Strait. The ridge will gradually transition to a high pressure center which will be pushed gradually eastward through Sunday night as a strong short wave drops southward out of the Russian Arctic Ocean. By late Sunday night the upper level high will be centered near Fort Yukon, with the strong short wave trough extending along 178W across the Chukchi Sea and Bering Sea. A series of weak short wave troughs will move westward across the southern interior through Saturday. A weak short wave trough is now moving westward across the central interior. The next short wave trough is now over the southern Yukon Territory and will move to the Alcan border by Friday morning then fracture into two troughs. The southern piece of the trough will continue to move westward and gradually deepen over the lower Kuskokwim Valley and southeastward Friday evening. The northern piece of the trough will stall out over the eastern interior Friday night and gradually weaken Saturday. SURFACE... A 1007 mb low centered near Northway will deepen to a 1001 mb low about 100 miles east of Northway by this afternoon, then remain nearly stationary through Saturday. A weak thermal trough will develop across the northern interior Saturday. INTERIOR... Areas or bands of showers and thunderstorms associated with the short wave troughs aloft will move westward across the southern interior and the Alaska Range, otherwise there will be isolated to scattered showers and isolated thunderstorms over most areas through the weekend. The heaviest rainfall today will likely be over Denali and the lower Kuskokwim Valley. The heaviest rainfall amounts tonight are expect to be in the lower Kuskokwim valley and in nearby area of the middle Yukon Valley. More showers and isolated thunderstorms are expected over much of the interior Saturday, and over much of the southern and eastern interior Sunday. ARCTIC SLOPE AND BROOKS RANGE... Areas of fog near the coast during the late night and early morning hours, otherwise no significant weather expected through Sunday. Warm temperatures in the interior with highs as high as the low to mid 70s. WEST COAST... No significant weather expected through Sunday. Some coastal areas may see areas of fog. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Some warming is expected in the interior over the weekend...with highs approaching or reaching 80 in some northern interior areas. Minimum humidities could approach 30 percent in the northern interior. Minimum humidities in the southern interior likely to remain at 35 percent or above. && .HYDROLOGY... Additional rainfall amounts of 0.5 to 1 inch are expected in Denali and the lower Kuskokwim Valley today. Northern parts of the Upper Tanana Valley and Fortymile country may see up to 0.5 inch, with local amounts of 0.75 inch possible. Locally heavier amounts will be possible in Denali and the lower Kuskokwim Valley today, but the location of the amounts remains uncertain due to the convective nature of the precipitation. && .AFG WATCHES/WARNINGS/ADVISORIES... Small craft advisory for PKZ245. && $$ RF JUN 16
Southcentral and Southwest Alaska Forecast Discussion...CORRECTED National Weather Service Anchorage AK 1108 PM AKDT THU JUN 30 2016 Corrected extended discussion .ANALYSIS AND UPPER LEVELS... The upper levels are starting to look like a mixed bag of goodies. The ever present upper level low spinning south of the gulf is slowly weakening but is continuing to eject shortwaves around it. The first of these waves moved across Southcentral last evening. The next is to the Northwest of PAYA and is noted on upper level analysis as an enhanced bubble of moisture and as a wiggle in the upper level analysis. This wave will move across the ALCAN border and across the Copper River Basin this afternoon. As of 2130z(1:30pm AKDT), showers are already beginning to form. This easterly wave will wrap around the low and slide across the Anchorage and Kenai areas tonight. A much more potent wave is easily identified in water vapor imagery near 49N 141W. As is the case with nearly stationary lows and these easterly waves that get ejected around, timing and placement has been a challenge. This strong wave is now progged to shift east and impact SE AK and BC. Farther west, a ridge between the Gulf low and a weakening Bering low is becoming pinched off as it retreats into the interior of Alaska. A strong upper level jet remains well south of the forecast area. At the surface, progress is being made on moving the nearly stationary low out of the gulf. A stalled out front stretches from a low in the Bering and southeast across the Akpen. && .MODEL DISCUSSION... All models are in pretty good agreement in the short term today. As briefly touched on in the analysis...the upper level low in the Gulf will shift east into the weaken. All of the models have varying levels of agreement with the shortwave strength and timing moving around the lows. The biggest trend from yesterday was slowing down the timing of the onset of the biggest rainmaker over Anchorage. The latest 18z runs of the NAM and GFS are showing a 9-12z time frame while the HRRR is hinting at an early start, between 5 and 6z. Judging by past performance of the HRRR and how poorly the major models play temporally, confidence in timing is low. However, all models are consistent with bringing in a healthy amount of rain across the region. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... Increasing mass ascent ahead of a low amplitude short wave trough over the Western Yukon and Eastern Copper Basin is beginning to manifest itself as increasing convective showers across the region. As the shortwave propagates west tonight, showers will begin to congeal into a large area of stratiform rain which will impact all of Southcentral tonight with brief periods of heavy rainfall. The heaviest axis of rain will likely occur across the Copper Basin into the Mat-Su Valleys, although areas along the Kenai and into Anchorage will also see the potential for brief heavy rains overnight. Thunderstorms have formed already along the Kenai Range, and they will also be possible along the Talkeetnas and Alaska Range as well as along the Chugach in the evening. The shortwave trough will elongate and quickly move west Friday, with most rain moving into Southwest Alaska by the afternoon. Showers will develop in the afternoon behind the main low, but these will be mainly along mountains and rather limited given lack of instability. Saturday will be warmer as broad cyclonic flow sets up over the region, with more afternoon showers but slightly warming temperatures. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... The upper level low over the Gulf continues to bring easterly flow with embedded shortwaves over Southwest Alaska. This combined with the unstable environment is helping to kick off thunderstorms over the area through Friday. The most likely times for thunderstorms are during peak heating and as the shortwaves move through. The shortwaves look to move through this evening, Friday morning and Friday evening. Friday will also see heavier rain from the Kuskokwim Valley south towards Bristol Bay and east towards the Alaska and Aleutian Ranges. Saturday will see a lesser chance for thunderstorms with the most likely area over the Kuskokwim Vally but rain will still be likely from the valley through Bristol Bay. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... A broad low over the Western Aleutians will last through the weekend slowly tracking east and bringing rain to the area. Areas from the Alaska Peninsula through the Pribilof Islands will be under the effects of weak ridging providing more fair conditions than areas to the west. && .LONG TERM FORECAST (Days 3 through 7)... On Sunday, the upper level pattern looks to grind to a halt from the easterly flow of weak disturbances to a much more chaotic movement. This will be due to the departure of the upper level low towards the Panhandle by Sunday morning, with no larger scale features following it. Thus, with everything being weak, any precipitation that develops Sunday over southern mainland Alaska will be scattered and weak. The persistence of a mid-level unstable layer over much of the area will result in some convection popping up with any showers that develop with enhanced lift, likely from topographic enhancement. For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...SS SOUTHCENTRAL ALASKA...JA SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK LONG TERM...JW Southeast Alaska Forecast Discussion National Weather Service Juneau AK 243 PM AKDT SAT JUL 2 2016 .SHORT TERM...A low pressure system is passing over Haida Gwaii this afternoon and looks pretty impressive on satellite imagery. The southern zones including Ketchikan and Hydaburg have had moderate rainfall for most of the day. Strongest winds have been limited to near the low center, but Annette Island has had gusts around 25mph. The low will weaken as it progresses east into Canada tonight. As this happens rain will become more showery and largely move out of the area through the evening. Winds will become more NWLY with the low to the SE and ease overnight. Across the norther inner channels precip has already transitioned to isolated showers with breaks of sunshine. Expect more breaks this evening as surface high pressure starts to build over the eastern gulf and the rest of the showers clear away. Exception to this will be Yakutat where a mid/upper level low and bands of vorticity will linger to the north through tomorrow afternoon. This will keep at least scattered showers in the forecast there. Some of the showers assoc with that upper level feature may spread over the rest of the north/central panhandle through Sunday afternoon, so have gone with isolated/scattered showers. Despite this there should be sunny breaks tomorrow, so nudge high temperatures up slightly. Used a blend of the GFS22 and Canadian Regional models for updates today. Forecast confidence is average. .LONG TERM...Quasi-zonal midlevel flow is forecast to occur over the gulf through midweek. An upper low then digs south of the panhandle on Friday. Though rain will be possible during the long term period, overall probabilities will generally be low, and amounts will be light. Bigger weather story will be the potential for a late week warm-up, as the system skirting south of the region on Friday induces northerly low-level flow that aids in downslope warming. Trended temperatures upward during the later half of the week as a result. No major changes were made to the previous forecast. Updated pressure grids past day 4 with 12Z WPC. Remainder of the grids were modified with an ensemble blend of model guidance, where necessary. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ012-036-041. Small Craft Advisory due to Seas for PKZ042. && $$ Ferrin/Garner Visit us at http://www.weather.gov/Juneau
  [top] Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 108 PM AKDT SAT JUL 2 2016 .DISCUSSION... MODELS...Similar solutions in the short term with very little spread. There is some disagreement on the location of the low aloft over the southeast interior on Monday that may effect convective activity. 02/12Z runs initialized well against the 02/18Z surface analysis. GFS and ECMWF spreading the precipitation far and wide, so will lean toward the NAM solution for the short term. They all have different ideas on where the heaviest precipitation will fall over the next couple days, so again will go with the NAM solution. ALOFT...At 500 HPA...A shortwave swinging around a 524 dam low in the high arctic will lie over the dateline this afternoon. A 542 dam low will develop over Wrangel Island tonight in the base of the trough, then move south over the Gulf of Anadyr by Monday morning at 547 dam as the trough expands south over the central Bering Sea. As the low break off the trough it will move southeast over the Pribilof Islands Tuesday afternoon, then over Bristol Bay by Wednesday morning, and over the Gulf of Alaska by Thursday morning. Weak ridging over the Brooks Range will persist, but be pushed east as the trough digs south, then moves north over the arctic as weak troughing develops over the interior on Monday. A 554 dam low over Yakutat will wobble around a bit through the weekend, then move north over the AlCan border Monday to MacKenzie Bay by Tuesday morning. Ridging will build north over the eastern Bering Sea on Wednesday. AT 850 HPA...A little cooler as the warm ridge that has been over the state continues to erode and move to the northeast. Zero isotherm remains north of the arctic coast this week. SURFACE...Pretty benign pattern over mainland Alaska. A broad area of low pressure dominates with a thermal trough over the central and eastern interior, and the upper Tanana Valley. Not expecting much change in the pattern except to see the trough move north a bit to the upper Yukon flats and south slopes of the Brooks range by Monday, then it drifts back to the south. Weak ridging will persist over the Gulf of Alaska and ridging will build east of the arctic coast today and persist over the coast and near shore waters through Tuesday. ARCTIC COAST AND BROOKS RANGE...A little bit of stratus around Barrow and Atqasuk but just a small band that appears to be dissipating. Should be partly cloudy this evening, then look for some stratus to develop over the coastal areas tonight with areas of fog. A cold front approaches the northwest coast, but it should stay offshore and dissipate or slide north of the coast. No significant winds expected in the short term, but they could get gusty from Barrow west as the front move near the area. Not much change in temperatures the next few days. A few showers in the eastern Brooks range the next couple days. WEST COAST AND WESTERN INTERIOR...Quiet along the coastal areas. A few patches of stratus may disrupt things, but should be pretty nice most of the time. Inland is a different story as isolated to scattered thunderstorms and showers will prevail for most areas through mid week. Highest concentration of thunderstorms and showers will be south of Huslia. Some patchy morning fog will also present some issues. Winds in most location will be light and variable. Temperatures a degree or two cooler the next few days. CENTRAL AND EASTERN INTERIOR...Showers will prevail with some isolated to scattered thunderstorms in the afternoons and evenings through mid week. Rainfall amounts will vary greatly, but the highest amounts appear to be in the eastern Alaska range at this time. No significant winds. Temperatures a couple degrees cooler. && .FIRE WEATHER...Unsettled wet and cool pattern will persist across the southern and eastern Interior with afternoon relative humidities remaining above 40 percent. Relatively drier conditions elsewhere across Northern Alaska will give way to the cool...wet unsettled pattern and increased afternoon relative humidities Monday as an longwave trough moves over the Bering Sea and West Coast. Isolated thunderstorms are possible over Interior from Galena to McGrath and east as well as the southeastern Brooks Range over the next few days. Instability will increase Sunday afternoon and evening to where scattered thunderstorms are expected to develop over an area from Lake Minchumina to Tanana and east including the Yukon Flats. There is the potential for scattered thunderstorms on Monday over the southeastern Interior, Yukon Flats, and southeastern Brooks Range. && .HYDROLOGY...Quite a few locations showing rises of 1 to 3 feet today, but all the gaged rivers are within banks. Another round of heavy rain possible in the eastern Alaska range with a chance it could move over the central Alaska range. Will be monitoring the area rainfall and gages in case further action needs to be taken. && .AFG WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory for PKZ210. && $$ SDB JUL 16
Southeast Alaska Forecast Discussion...Corrected National Weather Service Juneau AK 608 AM AKDT SAT JUL 2 2016 .SHORT TERM...The flood warning for the Mendenhall Lake and River has been cancelled early this morning. See the hydrology section below and the flood warning cancellation statement for additional information. Main weather feature over the next 24 hours will be a compact low pressure system tracking northeast across the northern portion of Haida Gwaii around midday before weakening and moving into British Columbia late tonight. This system is located in the left exit region of a 100 kt upper level jet which will aid in deepening it to around 1000 mb as it approaches Haida Gwaii. It rapidly loses jet support thereafter and will quickly weaken as a result. Aside from the far southern panhandle, the remainder of Southeast Alaska will transition to a weak flow regime. The effects of the compact low will be twofold. It will bring a period of enhanced lift and moderate to occasionally heavy rain through this afternoon for the southern panhandle. Additionally, a strong southeasterly low level jet with 925 mb winds of around 50 kt will increase winds over the far southern panhandle. However, with the track of the system the strongest winds are expected to remain over Dixon Entrance and south of the panhandle. For the northern panhandle, this low will act to shift flow to the east-southeast leading to diminishing rainfall chances through the day. Some peaks of blue sky and sun will even be possible across the northern half this afternoon and evening. Lingering gusty winds this morning associated with a weakening low near Cape Fairweather will also diminish through the morning with a weak pressure gradient and generally light winds in place later this afternoon and into tonight. Used the 06z NAM/GFS for updates to the short term forecast based upon good agreement on track and strength of low pressure system moving into the far southeast gulf. .LONG TERM...The low with the upper level support for the Saturday low over the Dixon Entrance region moves into British Columbia Sunday and as a result the main rain band will be pulling inland across the southern panhandle as well. A weak surface ridge over the eastern gulf will be displaced eastward across the panhandle. Meanwhile, a weak negatively tilted trough associated with a small weak low near Middleton Island Saturday night will stall along the coast of Southeast Alaska. Another weak low will move east across the western Gulf of Alaska, and a more organized low for mid next week. Aloft the main pattern is general westerly flow across the north Pacific and Gulf of Alaska. This has been the trend for the end of the week into the first half of next week so minimal changes were made. Kept the mostly cloudy and low chance level POP`s for rain. Wind should be 20 kt or less for the next several days. Confidence will be average through the mid to later parts of the forecast. The minor adjustments made to the forecast package was based on a NAM/GFS blend while the later periods were based on the WPC guidance. && .HYDROLOGY...Suicide Basin emptied on Friday afternoon with Mendenhall Lake cresting at 11.99 feet on Friday evening. This broke the previous record high crest of 11.85 feet in 2014. Water levels have receded rapidly overnight and will continue to do so through the weekend. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ036-041. Small Craft Advisory due to Seas for PKZ042-043. && $$ TPS/Bezenek Visit us at http://www.weather.gov/Juneau
Southeast Alaska Forecast Discussion National Weather Service Juneau AK 536 AM AKDT SAT JUL 2 2016 .SHORT TERM...The flood warning for the Mendenhall Lake and River has been cancelled early this morning. See the hydrology section below and the flood warning cancellation statement for additional information. Main weather feature over the next 24 hours will be a compact low pressure system tracking northeast across the northern portion of Haida Gwaii around midday before weakening and moving into British Columbia late tonight. This system is located in the left exit region of a 100 kt upper level jet which will aid in deepening it to around 1000 mb as it approaches Haida Gwaii. It rapidly loses jet support thereafter and will quickly weaken as a result. Aside from the far southern panhandle, the remainder of Southeast Alaska will transition to a weak flow regime. The effects of the compact low will be twofold. It will bring a period of enhanced lift and moderate to occasionally heavy rain through this afternoon for the southern panhandle. Additionally, a strong southeasterly low level jet with 925 mb winds of around 50 kt will increase winds over the far southern panhandle. However, with the track of the system the strongest winds are expected to remain over Dixon Entrance and south of the panhandle. For the northern panhandle, this low will act to shift flow to the east-southeast leading to diminishing rainfall chances through the day. Some peaks of blue sky and sun will even be possible across the northern half this afternoon and evening. Lingering gusty winds this morning associated with a weakening low near Cape Fairweather will also diminish through the morning with a weak pressure gradient and generally light winds in place later this afternoon and into tonight. Used the 06z NAM/GFS for updates to the short term forecast based upon good agreement on track and strength of low pressure system moving into the far southeast gulf. .LONG TERM...The low with the upper level support for the Saturday low over the Dixon Entrance region moves into British Columbia Sunday and as a result the main rain band will be pulling inland across the southern panhandle as well. A weak surface ridge over the eastern gulf will be displaced eastward across the panhandle. Meanwhile, a weak negatively tilted trough associated with a small weak low near Middleton Island Saturday night will stall along the coast of Southeast Alaska. Another weak low will move east across the western Gulf of Alaska, and more organized low for mid next week. Aloft the main pattern is general westerly flow pattern across the north Pacific and Gulf of Alaska. This has been the trend for the end of the week into the first half of next week so minimal changes were made. Kept the mostly cloudy and Low chance level PoP`s for rain. Wind should be 20 kt or less for the next several days. Confidence will be average through the mid to later parts of the forecast. the Minor adjustments made too the forecast package was based on a NAM/GFS blend while the later periods were based on the WPC guidance. && .HYDROLOGY...Suicide Basin emptied on Friday afternoon with Mendenhall Lake cresting at 11.99 feet on Friday evening. This broke the previous record high crest of 11.85 feet in 2014. Water levels have receded rapidly overnight and will continue to do so through the weekend. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ036-041. Small Craft Advisory due to Seas for PKZ042-043. && $$ TPS/Bezenek Visit us at http://www.weather.gov/Juneau
Southeast Alaska Forecast Discussion National Weather Service Juneau AK 536 AM AKDT SAT JUL 2 2016 .SHORT TERM...The flood warning for the Mendenhall Lake and River has been cancelled early this morning. See the hydrology section below and the flood warning cancellation statement for additional information. Main weather feature over the next 24 hours will be a compact low pressure system tracking northeast across the northern portion of Haida Gwaii around midday before weakening and moving into British Columbia late tonight. This system is located in the left exit region of a 100 kt upper level jet which will aid in deepening it to around 1000 mb as it approaches Haida Gwaii. It rapidly loses jet support thereafter and will quickly weaken as a result. Aside from the far southern panhandle, the remainder of Southeast Alaska will transition to a weak flow regime. The effects of the compact low will be twofold. It will bring a period of enhanced lift and moderate to occasionally heavy rain through this afternoon for the southern panhandle. Additionally, a strong southeasterly low level jet with 925 mb winds of around 50 kt will increase winds over the far southern panhandle. However, with the track of the system the strongest winds are expected to remain over Dixon Entrance and south of the panhandle. For the northern panhandle, this low will act to shift flow to the east-southeast leading to diminishing rainfall chances through the day. Some peaks of blue sky and sun will even be possible across the northern half this afternoon and evening. Lingering gusty winds this morning associated with a weakening low near Cape Fairweather will also diminish through the morning with a weak pressure gradient and generally light winds in place later this afternoon and into tonight. Used the 06z NAM/GFS for updates to the short term forecast based upon good agreement on track and strength of low pressure system moving into the far southeast gulf. .LONG TERM...The low with the upper level support for the Saturday low over the Dixon Entrance region moves into British Columbia Sunday and as a result the main rain band will be pulling inland across the southern panhandle as well. A weak surface ridge over the eastern gulf will be displaced eastward across the panhandle. Meanwhile, a weak negatively tilted trough associated with a small weak low near Middleton Island Saturday night will stall along the coast of Southeast Alaska. Another weak low will move east across the western Gulf of Alaska, and more organized low for mid next week. Aloft the main pattern is general westerly flow pattern across the north Pacific and Gulf of Alaska. This has been the trend for the end of the week into the first half of next week so minimal changes were made. Kept the mostly cloudy and Low chance level PoP`s for rain. Wind should be 20 kt or less for the next several days. Confidence will be average through the mid to later parts of the forecast. the Minor adjustments made too the forecast package was based on a NAM/GFS blend while the later periods were based on the WPC guidance. && .HYDROLOGY...Suicide Basin emptied on Friday afternoon with Mendenhall Lake cresting at 11.99 feet on Friday evening. This broke the previous record high crest of 11.85 feet in 2014. Water levels have receded rapidly overnight and will continue to do so through the weekend. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ036-041. Small Craft Advisory due to Seas for PKZ042-043. && $$ TPS/Bezenek Visit us at http://www.weather.gov/Juneau
  [top] Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 500 AM AKDT SAT JUL 2 2016 .ANALYSIS AND UPPER LEVELS... Upper level lows remain over the western Bering and the southeastern Gulf of Ak this morning, with a weak ridge along the west coast of the mainland. At the surface, a low is near Amchitka and a second is headed to Haida Gwaii. A weak ridge of high pressure is draped from the northwest Bering to Cold Bay, and a decaying front parallels the ridge slightly to its west. the thermal trough/theta-e ridge remains along the northern and western flanks of the Alaska and Aleutian ranges. && .MODEL DISCUSSION... Models are in general agreement that the Gulf upper and surface low complex are headed into southeast Ak today. The low will elongate and split with the main portion headed into British Columbia, and a smaller low drifting just east of the Alcan until dissipating early next week. An associated extremely weak surface low will drift in the northern Gulf through the period. As the upper low exits to the southeast it will send a few waves through the thermal trough today and Sun before the pattern shifts and the easterly waves come to an end. This will be caused by an upper trough digging south through the Bering Sun and Mon. In the west, the decaying front will be stretched as the Aleutian low weakens into a broad trough. The moisture rich remnants of the system will then interact with the diving trough later on Mon. The forecasts utilized some GFS and Nam to capture wave details. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2...Sat and Sun)... The strong disturbance bringing moderate to heavy rains to parts of Southwest Alaska will pivot in place over lower Cook Inlet later today and then significantly weaken. The associated rains with this system will impact Kodiak Island this morning, and then diminish in intensity over the Barren Islands, just clipping the southern Kachemak Bay region. Meanwhile...the rest of the area will remain in very light flow with generally moist and marginally unstable conditions. With all the recent rainfall...many places could see some patchy fog or low stratus develop overnight, but this should dissipate relatively quickly on Saturday as some sun breaks through. Showers should develop along the mountains in the afternoon, but with weak steering flow, we don`t expect many of them to make it into valleys. The best instability remains farther north over the Alaska Range and parts of the Talkeetna Mountains as well as the northern half of the Copper River Basin, so isolated thunderstorms are expected in these locations. Increasing southwesterly flow and an approaching upper disturbance Sunday into Sunday night will mean a slow stabilizing trend as we approach the Independence Day holiday Monday. Expect more robust shower activity over the Kenai Range Sunday afternoon and evening, and as 850-mb and 700-mb southwesterly flow increases, we cannot at this time rule out at least some chance of light rain pushing north off of the mountains into parts of Anchorage and the Matanuska Valley late Sunday night into early Monday. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... The cloudy rainy pattern over the mainland will continue the next two days with decreasing coverage each day. Steady rain will shift from the Kuskokwim Valley southward into Greater Bristol Bay during the afternoon. The Kuskokwim Delta will be right on the edge of the disturbance over the Eastern Mainland, and should stay mostly shower-free save for areas south and east of Bethel in the afternoon/evening hours. Overnight into Sunday most of the rain will be confined to the higher elevations of the Kuskokwim Valley. The flow pattern changes on Monday in response to a developing trough in the Western Bering Sea, which will result in continued cloudiness and a small chance for light rain. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... The upper level low pressure system over the western Bering continues to weaken. A disturbance within the flow will weaken over the Eastern Aleutians and Alaska Peninsula today as light rain tapers off to sprinkles. The large scale trough stays in the area continuing a small chance for light rain before a stronger disturbance drops into the northwestern Bering late Sunday night. && .LONG TERM FORECAST (Days 3 through 7)... For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...DS SOUTHCENTRAL ALASKA...CC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML LONG TERM...TP/DS
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 500 AM AKDT SAT JUL 2 2016 .ANALYSIS AND UPPER LEVELS... Upper level lows remain over the western Bering and the southeastern Gulf of Ak this morning, with a weak ridge along the west coast of the mainland. At the surface, a low is near Amchitka and a second is headed to Haida Gwaii. A weak ridge of high pressure is draped from the northwest Bering to Cold Bay, and a decaying front parallels the ridge slightly to its west. the thermal trough/theta-e ridge remains along the northern and western flanks of the Alaska and Aleutian ranges. && .MODEL DISCUSSION... Models are in general agreement that the Gulf upper and surface low complex are headed into southeast Ak today. The low will elongate and split with the main portion headed into British Columbia, and a smaller low drifting just east of the Alcan until dissipating early next week. An associated extremely weak surface low will drift in the northern Gulf through the period. As the upper low exits to the southeast it will send a few waves through the thermal trough today and Sun before the pattern shifts and the easterly waves come to an end. This will be caused by an upper trough digging south through the Bering Sun and Mon. In the west, the decaying front will be stretched as the Aleutian low weakens into a broad trough. The moisture rich remnants of the system will then interact with the diving trough later on Mon. The forecasts utilized some GFS and Nam to capture wave details. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2...Sat and Sun)... The strong disturbance bringing moderate to heavy rains to parts of Southwest Alaska will pivot in place over lower Cook Inlet later today and then significantly weaken. The associated rains with this system will impact Kodiak Island this morning, and then diminish in intensity over the Barren Islands, just clipping the southern Kachemak Bay region. Meanwhile...the rest of the area will remain in very light flow with generally moist and marginally unstable conditions. With all the recent rainfall...many places could see some patchy fog or low stratus develop overnight, but this should dissipate relatively quickly on Saturday as some sun breaks through. Showers should develop along the mountains in the afternoon, but with weak steering flow, we don`t expect many of them to make it into valleys. The best instability remains farther north over the Alaska Range and parts of the Talkeetna Mountains as well as the northern half of the Copper River Basin, so isolated thunderstorms are expected in these locations. Increasing southwesterly flow and an approaching upper disturbance Sunday into Sunday night will mean a slow stabilizing trend as we approach the Independence Day holiday Monday. Expect more robust shower activity over the Kenai Range Sunday afternoon and evening, and as 850-mb and 700-mb southwesterly flow increases, we cannot at this time rule out at least some chance of light rain pushing north off of the mountains into parts of Anchorage and the Matanuska Valley late Sunday night into early Monday. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... The cloudy rainy pattern over the mainland will continue the next two days with decreasing coverage each day. Steady rain will shift from the Kuskokwim Valley southward into Greater Bristol Bay during the afternoon. The Kuskokwim Delta will be right on the edge of the disturbance over the Eastern Mainland, and should stay mostly shower-free save for areas south and east of Bethel in the afternoon/evening hours. Overnight into Sunday most of the rain will be confined to the higher elevations of the Kuskokwim Valley. The flow pattern changes on Monday in response to a developing trough in the Western Bering Sea, which will result in continued cloudiness and a small chance for light rain. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... The upper level low pressure system over the western Bering continues to weaken. A disturbance within the flow will weaken over the Eastern Aleutians and Alaska Peninsula today as light rain tapers off to sprinkles. The large scale trough stays in the area continuing a small chance for light rain before a stronger disturbance drops into the northwestern Bering late Sunday night. && .LONG TERM FORECAST (Days 3 through 7)... For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...DS SOUTHCENTRAL ALASKA...CC SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML LONG TERM...TP/DS
Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 419 AM AKDT SAT JUL 2 2016 .DISCUSSION... UPPER AIR... A weak ridge currently extends from St Lawrence Island to the eastern Beaufort Sea then links up to a much stronger ridge over northwest Canada. The Alaskan portion of the ridge will gradually weaken through Saturday night, with the main high pressure aloft remaining over northwestern Canada by Sunday afternoon. A more organized mainly southerly flow pattern aloft will become established over the northern Alaska Mainland by Monday afternoon. A weak upper low will develop over the extreme southern Yukon Territory this afternoon, remain nearly stationary through Sunday night, then weakening into a trough lifting northward across the eastern Alaska interior Monday through Tuesday. A weak short wave trough along the Alcan border south of the Brooks Range will move to the southeast interior by this afternoon, weakening into a weak upper low near the middle Tanana Valley by this evening. This feature will weaken into a weak trough over Denali by Sunday afternoon, then dissipate Sunday night. A strong short wave trough extending from 80N/180W to the New Siberian Islands will swing eastward around a strong upper low over the north polar region. By late tonight the short wave will extend from 80N/160E to Wrangel Island and southward into the Russian mainland. The trough will then remain stationary through Sunday night while deepening into an elongated low extending from Wrangel Island to south of the Gulf of Anadyr. SURFACE... A 1002 mb low centered about 100 miles east of Northway will weaken to a 1002 mb low centered 100 miles east of Fort Yukon by late tonight. A 1002 mb low will develop 50 miles west of Bettles this afternoon with a weak thermal trough extending eastward into the upper Yukon Valley. This thermal trough will gradually intensify through Sunday and weaken to the northern Brooks Range by Monday afternoon, with a main 1006 mb thermal low over the central Brooks Range. A weak high pressure ridge will expand eastward across the Beaufort Sea tonight, with a 1014 mb high forming 300 miles north of Deadhorse by Sunday evening. The high will build to 1020 mb by Monday evening as it moves northeastward to Prince Patrick Island in the Canadian archipelago. A 1020 mb high centered west of the New Siberian Islands will weaken to a 1015 mb high centered near Wrangel Island by Monday morning. INTERIOR... Today and this evening..Showers and isolated thunderstorms are expected over most areas. Convective activity could be enhanced by a weak short wave trough along the Alcan border. The greatest instability this afternoon and evening will be over the western interior. Showers likely continuing into the late night hours. Sunday and Sunday evening...Showers and isolated thunderstorms continuing over the central and eastern interior. Scattered showers and isolated thunderstorms also possible in the upper Kuskokwim Valley. Showers likely continuing into the late night hours. Monday and Monday evening...Showers and isolated thunderstorms continuing over almost all of the central and eastern interior, and in extreme southern parts of the western interior. The most instability is expected to be over the northeastern interior, GFS indicating areas of 800-1000 J/kg surface CAPE with surface lifted index as low as -3. There is potential for the thunderstorm activity to be scattered in parts of the northeast interior, but at this time we will stay with isolated activity. Future model runs will need to be monitored. A weakening short wave trough moving northward across the eastern interior could enhance thunderstorm activity as well as triggering extensive showers. Showers likely continuing into the late night hours. WEST COAST... No significant weather expected through Monday. Patchy coastal fog in some areas. ARCTIC SLOPE AND BROOKS RANGE... Warm temperatures continuing through Monday...especially in the interior where high temperatures will reach 70 or higher in many areas. Patchy fog possible along the coast during the late night and early morning hours. Scattered rain showers over the northeastern Brooks Range Sunday night and Monday, with isolated thunderstorms Monday afternoon. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Minimum RH expected to be 40% or higher over most interior areas today. Warmer temperatures over the northern and northeastern interior Sunday and Monday. Minimum humidities are expected to be lower, but still above 30-35 percent. Forecast CAPE and lifted index numbers indicate the possibility of scattered thunderstorms in parts of the northeastern interior Monday. We are going with isolated thunderstorms on this mornings forecast package, but forecast CAPE and lifted index on future model runs will need to be monitored. && .HYDROLOGY... Given the high precipitable water values (1 to 1.2 inches) in parts of the central and eastern interior through Tuesday, there is potential for locally heavy showers which, if they occur in mountainous terrain, could cause small stream flood issues. Rain gage data will need to be closely monitored. && .AFG WATCHES/WARNINGS/ADVISORIES... None. && $$ RF JUL 16
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 441 PM AKDT FRI JUL 1 2016 .ANALYSIS AND UPPER LEVELS... The upper level low remains over the Gulf of Alaska, but is beginning to show signs of moving east. The strong short-wave system on the northwest side of the low that provided last nights rainfall to south central Alaska is now in southwest Alaska. There is an upper level low over the southwest Bering Sea as well as the western and central Aleutians. This low has stalled and is continuing to weaken. A weather front associated with this low stretches from about Nikolski northwestward across the Bering Sea. A ridge of high pressure separates these two low, with the "col" over the far eastern Bering. && .MODEL DISCUSSION... The numerical models are in reasonable agreement on the over-all pattern. There continue to be some differences in the timing, location, and strength of various short-waves surrounding the Gulf low. There are also some minor differences in the handling of precipitation, especially in regards to convection. Therefore the forecast confidence is slightly below normal. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2...Sat and Sun)... Afternoon mountain showers and diurnal sea breezes will be the story for the weekend. The easterly wave that brought a third to an inch and half of rain across Southcentral has cleared through most of the area. The Alaska Range has slowed its westward progress keeping some rain falling over Kachemak Bay. It will pivot through this corridor on Sat bringing rain to parts of Kodiak Island later tonight through the Sat morning hours. Meanwhile...the rest of the area will remain in very light flow with generally moist and unstable conditions. With all the recent rainfall...many places could see some patchy fog or low stratus develop overnight. But this should dissipate relatively quickly on Saturday as some sun breaks through. Showers should develop along the mountains in the afternoon, but with weak steering flow, we don`t expect many of them to make it into valleys. The best instability remains farther north over the Alaska Range and parts of the Talkeetna Mountains, so can`t rule out an isolated thunderstorm developing on those higher peaks. Sun looks very similar to Sat with minimal change to the pattern. The leftover band of rain near Kodiak should move off into the Gulf making for drying conditions there. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... The Gulf low that has been relatively stationary the last couple of days will finally push off to the east tonight. This will change the easterly flow over the area to be more northerly which will help to diminish showers over the area. The majority of the rain remaining by the beginning of next week will be in the more eastern parts of Southwest Alaska like the Alaska and Aleutian Ranges. Even though the main upper level low is departing there are still more shortwaves moving through the area with the strongest one coming through this evening. It will track south from the Kuskokwim Valley towards Bristol Bay and will help to initiate thunderstorms in the area. There will also be enough instability over the Kuskokwim Valley for possible afternoon thunderstorms Saturday and Sunday. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... The broad area of low pressure over the Western Aleutians will track slowly east over the weekend. It looks to bring light rain to the Aleutians with some making it to the Pribilof Islands on Saturday. By the beginning of next week the broad upper level low will be absorbed into a broad trough extending across the Bering from the north. This trough will keep light rain over the Bering and Aleutians. && .LONG TERM FORECAST (Days 3 through 7)... The upper level pattern will begin to shift by the end of this weekend to a more stable pattern, as the upper low shifts further east and weak high pressure aloft builds in from the west. Thus, with everything being weak, any precipitation that develops Sunday over southern mainland Alaska will be mostly scattered and weak. The persistence of a mid-level unstable layer over much of the area will result in some diurnal showers mainly along the mountains. For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...BL SOUTHCENTRAL ALASKA...MO SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK LONG TERM...TP
Southeast Alaska Forecast Discussion National Weather Service Juneau AK 324 PM AKDT FRI JUL 1 2016 .SHORT TERM...A low just west of Sitka this afternoon continues to track north along the outer coast. Visible and WV satellite imagery is clearly depicting the circulation, but it is not nearly as evident in IR imagery. Radar has been showing banding in the returns, but the total system is slightly stronger than originally expected and had produced 30 kts of wind in Clarence Strait earlier today. Morning model runs still showing some divergence on the low center. With the system so close to the outer coast, minor differences in location, track, and intensity can have significant impacts in the forecast. That said, opted for the NAM for updates to pressure and winds today. Resulting changes primarily affect the winds over the eastern gulf and coastal locations north of Cape Decision. On the inside, result was to increase winds speeds a bit, so the afternoon forecast features small craft advisories for several of the inner channels. Clarence Strait is expected to continue at high end small craft intensity through the evening before relaxing. A low approaching the Dixon Entrance from the southwest tomorrow will produce another round of small craft winds out of the east tomorrow afternoon, but these winds will be mostly over southern areas near the Dixon Entrance. Small craft southerlies will get into the ocean entrances of Chatham Strait and Sumner Strait early this evening but should diminish to 15 kts or so by tomorrow morning. Also expect small craft winds out of the east over eastern portions of Sumner and southeasterlies to 25 kts along Frederick Sound south of Cape Fanshaw. Later tonight, max winds on the inside will shift north to include Stephens passage north of Taku inlet, the northern portions of Chatham Strait, and much of Icy Strait. Finally, easterly Small Craft winds to 30 kts from late this evening through tomorrow afternoon are forecast for Cross Sound. Small craft winds on the outside will progress from south to north as well, ending late morning as the low weakens and fills vicinity of Cape Fairweather. POP forecast from last night still looks good, so no changes there. Did update QPF using a blend of Canadian REG and NAMDNG. Overall forecast confidence is average to below average due to uncertainties in how inner channel winds will respond to the low off the coast. .LONG TERM...The low passing through Dixon Entrance Saturday night will keep showers largely confined to the southern panhandle. An upper level low shifts south Saturday night then looks to settle over central BC Sunday. This will also help to clear away showers initially over the north, but then once its in Canada may cause clouds and some showers to move in from the east. For this reason chance/slight chance of showers remain in the forecast over the weekend. Weak ridging will develop over the gulf starting Monday, or a better way to describe it, zonal onshore flow. This leads to a chance of rain in the forecast, or at least a bit more cloud cover. There are some indications that a marine layer could develop over the gulf under the ridge, this will be monitored over the next couple days. If an inversion develops or there is a low cloud deck that would be of concern for Monday night activities along the outer coast. Adjusted temps up slightly through the extended forecast as both base models and bias corrected models were warmer. Thinking that sunny breaks in the clouds will allow for more seasonable highs in the mid 60s. Used an ensemble approach for updates today. Model agreement on pressure was good through the mid range then diverged day 6, used more WPC guidance for later periods. Model differences on the POP forecast were still fairly high over the holiday, so still lower confidence in that part of the forecast. && .HYDROLOGY...Early afternoon indications are that Suicide Basin may have emptied out. The lake, however, will continue to rise through the evening, with a forecast crest of at or near 12 feet later tonight. See the flood warning issued by NWS Juneau for details and be careful and vigilant around flood waters. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ021-022-031>036-041>043. && $$ Fritsch/Ferrin Visit us at http://www.weather.gov/Juneau
Southeast Alaska Forecast Discussion National Weather Service Juneau AK 324 PM AKDT FRI JUL 1 2016 .SHORT TERM...A low just west of Sitka this afternoon continues to track north along the outer coast. Visible and WV satellite imagery is clearly depicting the circulation, but it is not nearly as evident in IR imagery. Radar has been showing banding in the returns, but the total system is slightly stronger than originally expected and had produced 30 kts of wind in Clarence Strait earlier today. Morning model runs still showing some divergence on the low center. With the system so close to the outer coast, minor differences in location, track, and intensity can have significant impacts in the forecast. That said, opted for the NAM for updates to pressure and winds today. Resulting changes primarily affect the winds over the eastern gulf and coastal locations north of Cape Decision. On the inside, result was to increase winds speeds a bit, so the afternoon forecast features small craft advisories for several of the inner channels. Clarence Strait is expected to continue at high end small craft intensity through the evening before relaxing. A low approaching the Dixon Entrance from the southwest tomorrow will produce another round of small craft winds out of the east tomorrow afternoon, but these winds will be mostly over southern areas near the Dixon Entrance. Small craft southerlies will get into the ocean entrances of Chatham Strait and Sumner Strait early this evening but should diminish to 15 kts or so by tomorrow morning. Also expect small craft winds out of the east over eastern portions of Sumner and southeasterlies to 25 kts along Frederick Sound south of Cape Fanshaw. Later tonight, max winds on the inside will shift north to include Stephens passage north of Taku inlet, the northern portions of Chatham Strait, and much of Icy Strait. Finally, easterly Small Craft winds to 30 kts from late this evening through tomorrow afternoon are forecast for Cross Sound. Small craft winds on the outside will progress from south to north as well, ending late morning as the low weakens and fills vicinity of Cape Fairweather. POP forecast from last night still looks good, so no changes there. Did update QPF using a blend of Canadian REG and NAMDNG. Overall forecast confidence is average to below average due to uncertainties in how inner channel winds will respond to the low off the coast. .LONG TERM...The low passing through Dixon Entrance Saturday night will keep showers largely confined to the southern panhandle. An upper level low shifts south Saturday night then looks to settle over central BC Sunday. This will also help to clear away showers initially over the north, but then once its in Canada may cause clouds and some showers to move in from the east. For this reason chance/slight chance of showers remain in the forecast over the weekend. Weak ridging will develop over the gulf starting Monday, or a better way to describe it, zonal onshore flow. This leads to a chance of rain in the forecast, or at least a bit more cloud cover. There are some indications that a marine layer could develop over the gulf under the ridge, this will be monitored over the next couple days. If an inversion develops or there is a low cloud deck that would be of concern for Monday night activities along the outer coast. Adjusted temps up slightly through the extended forecast as both base models and bias corrected models were warmer. Thinking that sunny breaks in the clouds will allow for more seasonable highs in the mid 60s. Used an ensemble approach for updates today. Model agreement on pressure was good through the mid range then diverged day 6, used more WPC guidance for later periods. Model differences on the POP forecast were still fairly high over the holiday, so still lower confidence in that part of the forecast. && .HYDROLOGY...Early afternoon indications are that Suicide Basin may have emptied out. The lake, however, will continue to rise through the evening, with a forecast crest of at or near 12 feet later tonight. See the flood warning issued by NWS Juneau for details and be careful and vigilant around flood waters. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ021-022-031>036-041>043. && $$ Fritsch/Ferrin Visit us at http://www.weather.gov/Juneau
Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 303 PM AKDT FRI JUL 1 2016 .SYNOPSIS... Aloft... A ridge stretching east to west across northern Alaska will persist through the weekend then retreat east in NW Canada next week as a trough develops over the Bering Sea. A low aloft in the Gulf of Alaska will move over SE Alaska Sat and then move slowly east. A series of short wave troughs rotating around this low will move west across Interior Alaska bringing bands of showers and isolated to scattered thunderstorms to the eastern and southern Interior through the weekend. A strong short wave that now lies from Denali to Livengood to Old Crow will move to McGrath to Tanana to Arctic Village by 4am Sat...and then weaken in place through Sun. There is a wide band of showers NW of this trough that becomes scattered north of the Yukon River. This dropped .10 to .25 inch of rain over the eastern Interior south of Circle with up to .50 inch in the hills north of Fox and east of Delta Junction. Expect this to drop another .50 to 1 inch over zones 221 225 and 227 through Sat with the heaviest amounts in Denali Park. From .50-1.5 inch of rain has already fallen in Denali Park so this will keep small stream and rivers there high through the weekend and could still cause mud and rock slides. A second and weaker short wave trough near Old Crow will move to Fort Yukon by 4am Sat...to Denali to Livengood by 4pm Sat...and then slowly dissipate through Sun. This will cause scattered showers and scattered PM thunderstorms in eastern zone 216 western 221 and 227 Sat and into Sun. The thunderstorms could have small hail Sat. A third short wave trough over the southern Yukon Territory will move to the ALCAN Border by 4pm Sat and then weaken over the eastern Interior through Sun. This will bring more widespread showers to zones 224 226 Sat into Sun and keep scattered showers and at least isolated thunderstorms going in the remainder of the eastern Interior. There is the potential for hail again Sun and this will need to be watched. A fourth short wave is expected to move to the extreme SE interior Sun night and Mon and could bring heavy rain...but this still has a lot of uncertainty. Surface... An Arctic warm front from Barter Island to Deadhorse will move to Barter Island north by 4am Sat then move north of the coast. Expect fog to reform along this front tonight and then move offshore Sat. A 1022 mb high over the central Bering Sea will weaken slowly through Sun. An Arctic cold front in the western Chukchi Sea will move east to Barrow to Cape Lisburne then west by 4pm Sat...to Deadhorse to a 1007 mb low near Point Hope by 4am Sun...and then quasi- stationary. Fog and a chance of rain will accompany the front. Westerly flow will increase south of the low center and should return widespread fog to the southern Chukchi and north Bering Seas and most of the West Coast of AK by Sat night. && .DISCUSSION... Models are similar on the large scale flow pattern and features but differ some on timing and location of weak short wave troughs moving west across the Interior. Since these weak short wave troughs are the main force driving convection over the interior the location is important. We favor the GFS locations of the short waves and heavy rain through Sat night Sun and then the flow becomes so weak that we can really only deal with short wave location and accompanying rainfall in a probabilistic sense. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Continued wet across southern and eastern Interior with drier and warmer conditions in the northwest Interior. Expect isolated thunderstorms a a few lightning strikes today and Sat...except LAL 3 Sat in eastern Zone 216...western 221 and 227. Sun could see LAL 3 over the eastern Interior but uncertain at this point so left it as LAL 2 for Sun. && .HYDROLOGY... The past 36 hrs saw .10 to .25 inch of rain fall over the eastern Interior south of Circle with up to .50 inch in the hills north of Fox and hills east of Delta Junction...while Denali Park had between .50-1.5 inch. Expect another .50 to 1 inch over zones 221 225 and 227 through Sat with the heaviest amounts in Denali Park. This will keep small stream and rivers in Denali high through the weekend and could cause mud and rock slides through the weekend. There is a potential for heavy rain in zones 224 and 226 SE of Tok Sun night and Mon but still much uncertainty on this. && .AFG WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory for PKZ245. && $$ JB JUL 16
Southeast Alaska Forecast Discussion National Weather Service Juneau AK 533 AM AKDT FRI JUL 1 2016 .SHORT TERM...The biggest story over the next 24 hours is the ongoing glacial dam release from Suicide Basin into Mendenhall Lake and River. This will be covered further in the hydrology section below. As for the weather, the main feature is a 1000 mb low pressure system currently in the southeast gulf which will gradually weaken while moving north to near Cape Fairweather by late tonight. A secondary wave of low pressure will develop southwest of Haida Gwaii late tonight but is expected to remain south of the area. Stratiform rainfall is currently ongoing across the southern half of the panhandle aided by warm air advection in association with the advancing low. This will continue to spread northward through the day reaching the Juneau area this morning and the far northern panhandle this afternoon. Precipitation chances will remain high throughout the next 24 hours across all of Southeast Alaska. Expecting rainfall totals to generally range from one half of an inch to an inch with heaviest amounts over the southern panhandle. This system will enhance winds over the southern half of the area but am only expecting 10 to 20 mph for the land areas and 20-25 kt for the inner channels. Decreased winds across the far northern panhandle as a parallel pressure gradient to Northern Lynn Canal will lead to lighter winds. Used the 06z NAM and Hi-Res model guidance for updates to the short term period. Forecaster confidence is above average. .LONG TERM...Through the weekend, generally a zonal flow pattern in place across the north Pacific aloft. The closed low at 500 mb over the Gulf of Alaska weakens and moves into western Canada Monday while a broad weak ridge aloft forms over the western gulf. Weak to null flow aloft over the northern panhandle will be in place headed into early next week. Long range trend for Southeast Alaska looks to be for a development around mid week to the end of the week over the gulf. A surface low near Cape Fairweather is weakening, while a low moving across the southern gulf along 50N and then curving north across Haida Gwaii on Saturday. This will spread rain into the southern half of the panhandle. Saturday evening the low will move into British Columbia while the low off of Cross Sound dissipates. The surface pattern across the gulf Friday into Saturday becomes west to northwest. The potential for low probability showers from onshore flow will exist along the outer coast Sunday into Monday. With the main flow pattern to the south of the forecast area not expecting a significant weather system for the next few days. && .HYDROLOGY...Suicide Basin has released and a flood warning is in effect for Mendenhall River and Lake until Saturday morning. The current forecast crest of 11.6 feet is close to the previous record value of 11.85 feet set in 2014. As of early this morning, Mendenhall Lake had risen to a stage of 8.5 feet and the rate of rise is steadily increasing as expected. The level in Suicide Basin continues to fall rapidly. Residents near the lake or the river should remain alert and keep track of updates to this event as they are issued by NWS Juneau. && .AJK Watches/Warnings/Advisories... PUBLIC...None. MARINE...Small Craft Advisory for PKZ033>036-041>043. && $$ TPS/Bezenek Visit us at http://www.weather.gov/Juneau
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 447 AM AKDT FRI JUL 1 2016 .ANALYSIS AND UPPER LEVELS... Upper level lows are over the western Bering and the southern Gulf of Ak this morning with the jet remaining well south of the forecast area. At the surface, lows are near Attu and over the eastern Gulf. A ridge of high pressure is over the eastern Bering. The thermal trough/theta-e ridge is draped along the Alaska and Aleutian ranges and is serving as the focus for showers and even a few nocturnal thunderstorms. && .MODEL DISCUSSION... Models remain in agreement that the Gulf upper low will slowly rotate its way into British Columbia by Sun morning. Easterly waves moving along the northern flank of the low will interact with the moisture rich thermal trough/theta-e ridge through the weekend. This may explain what is happening, but these waves are poorly timed in model solutions, so exactly when precipitation initiation and enhancement will occur remains a problem. The forecast utilizes some Nam and GFS in an attempt to pinpoint some of the precipitation events. In the west the surface low will drift and weaken over the western Aleutians through the weekend. A weak associated front will move to the central Aleutians during the same period. Again the Nam and GFS were utilized in the forecast. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... The last of a series of fairly strong short-waves crossing westward across Southcentral Alaska this morning will exit to Southwest Alaska this afternoon bringing an end to widespread showers and rain. However, as the large upper low over the Gulf tracks eastward today and tonight, short-waves tracking across Southwest Alaska will rotate southeastward across Kodiak Island and the western Gulf bringing widespread showers to that region. In the wake of the upper level low the flow across the region will become more and more chaotic, with weak impulses wandering around. This creates a lot of uncertainty in the forecast. Have used a broadbrush approach to the precip forecast for tonight through Saturday night. In this scenario would expect more showers during the afternoon and evening hours focused along the mountains. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... Clouds, rain, and thunderstorms will be the focus for Friday and Saturday. Widespread showers with embedded thunderstorms will encompass the Kuskokwim Valley southward through Greater Bristol Bay today. A lesser chance exists over the Kuskokwim Delta, but afternoon showers and a slight chance for thunder are possible. Nearly the same conditions are on tap for Saturday, however, any thunderstorms will stay confined to the Kuskokwim Valley along the Alaska Range. For the Delta, most of the shower activity will be east of Bethel along the Kilbucks. Winds will be on the lighter side everywhere, and temperatures will be well above average for this time of year. Technically speaking...A large upper level low in the gulf controls the pattern, but the real action is rotating around the circulation in the form of embedded easterly shortwaves. Feeding on the baroclinity from the difference between the cooler gulf airmass and the warmer Interior/Yukon airmass, these waves amplify and provide the forcing for diurnally enhanced showers and thunderstorms. Ridging over the northern portion of the state is breeding warm low level temperatures that will be advected down into the Southwest Mainland, as well as some juicy dewpoints by Alaska standards. These conditions are ripe for frequent lightning over mainly the Kuskokwim Valley and into Bristol Bay today. The upper level energy lingers through the weekend keeping at least showers in the forecast. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... A weakening system aloft over the Western Bering will bring rain today from Shemya through the Central Aleutians, and as far east as the Eastern Aleutians. That system will weaken through the weekend and not produce meaningful precipitation after today. A fairly narrow corridor of dense fog will set up today roughly from Saint Matthew through the Pribilofs and linger through tonight. && .LONG TERM FORECAST (Days 3 through 7)... On Sunday, the upper level pattern looks to grind to a halt from the easterly flow of weak disturbances to a much more chaotic movement. This will be due to the departure of the upper level low towards the Panhandle by Sunday morning, with no larger scale features following it. Thus, with everything being weak, any precipitation that develops Sunday over southern mainland Alaska will be scattered and weak. The persistence of a mid-level unstable layer over much of the area will result in some convection popping up with any showers that develop with enhanced lift, likely from topographic enhancement. For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...DS SOUTHCENTRAL ALASKA...SEB SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML LONG TERM...JW
Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 418 AM AKDT FRI JUL 1 2016 .DISCUSSION... UPPER AIR... A high pressure ridge currently extends from the Chukotsk Peninsula eastward across the Brooks Range into northwestern Canada, with a high center near the Bering Strait. The ridge will gradually transition to a high pressure center which will be pushed gradually eastward through Sunday night as a strong short wave drops southward out of the Russian Arctic Ocean. By late Sunday night the upper level high will be centered near Fort Yukon, with the strong short wave trough extending along 178W across the Chukchi Sea and Bering Sea. A series of weak short wave troughs will move westward across the southern interior through Saturday. A weak short wave trough is now moving westward across the central interior. The next short wave trough is now over the southern Yukon Territory and will move to the Alcan border by Friday morning then fracture into two troughs. The southern piece of the trough will continue to move westward and gradually deepen over the lower Kuskokwim Valley and southeastward Friday evening. The northern piece of the trough will stall out over the eastern interior Friday night and gradually weaken Saturday. SURFACE... A 1007 mb low centered near Northway will deepen to a 1001 mb low about 100 miles east of Northway by this afternoon, then remain nearly stationary through Saturday. A weak thermal trough will develop across the northern interior Saturday. INTERIOR... Areas or bands of showers and thunderstorms associated with the short wave troughs aloft will move westward across the southern interior and the Alaska Range, otherwise there will be isolated to scattered showers and isolated thunderstorms over most areas through the weekend. The heaviest rainfall today will likely be over Denali and the lower Kuskokwim Valley. The heaviest rainfall amounts tonight are expect to be in the lower Kuskokwim valley and in nearby area of the middle Yukon Valley. More showers and isolated thunderstorms are expected over much of the interior Saturday, and over much of the southern and eastern interior Sunday. ARCTIC SLOPE AND BROOKS RANGE... Areas of fog near the coast during the late night and early morning hours, otherwise no significant weather expected through Sunday. Warm temperatures in the interior with highs as high as the low to mid 70s. WEST COAST... No significant weather expected through Sunday. Some coastal areas may see areas of fog. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Some warming is expected in the interior over the weekend...with highs approaching or reaching 80 in some northern interior areas. Minimum humidities could approach 30 percent in the northern interior. Minimum humidities in the southern interior likely to remain at 35 percent or above. && .HYDROLOGY... Additional rainfall amounts of 0.5 to 1 inch are expected in Denali and the lower Kuskokwim Valley today. Northern parts of the Upper Tanana Valley and Fortymile country may see up to 0.5 inch, with local amounts of 0.75 inch possible. Locally heavier amounts will be possible in Denali and the lower Kuskokwim Valley today, but the location of the amounts remains uncertain due to the convective nature of the precipitation. && .AFG WATCHES/WARNINGS/ADVISORIES... Small craft advisory for PKZ245. && $$ RF JUN 16
Northern Alaska Forecast Discussion National Weather Service Fairbanks AK 418 AM AKDT FRI JUL 1 2016 .DISCUSSION... UPPER AIR... A high pressure ridge currently extends from the Chukotsk Peninsula eastward across the Brooks Range into northwestern Canada, with a high center near the Bering Strait. The ridge will gradually transition to a high pressure center which will be pushed gradually eastward through Sunday night as a strong short wave drops southward out of the Russian Arctic Ocean. By late Sunday night the upper level high will be centered near Fort Yukon, with the strong short wave trough extending along 178W across the Chukchi Sea and Bering Sea. A series of weak short wave troughs will move westward across the southern interior through Saturday. A weak short wave trough is now moving westward across the central interior. The next short wave trough is now over the southern Yukon Territory and will move to the Alcan border by Friday morning then fracture into two troughs. The southern piece of the trough will continue to move westward and gradually deepen over the lower Kuskokwim Valley and southeastward Friday evening. The northern piece of the trough will stall out over the eastern interior Friday night and gradually weaken Saturday. SURFACE... A 1007 mb low centered near Northway will deepen to a 1001 mb low about 100 miles east of Northway by this afternoon, then remain nearly stationary through Saturday. A weak thermal trough will develop across the northern interior Saturday. INTERIOR... Areas or bands of showers and thunderstorms associated with the short wave troughs aloft will move westward across the southern interior and the Alaska Range, otherwise there will be isolated to scattered showers and isolated thunderstorms over most areas through the weekend. The heaviest rainfall today will likely be over Denali and the lower Kuskokwim Valley. The heaviest rainfall amounts tonight are expect to be in the lower Kuskokwim valley and in nearby area of the middle Yukon Valley. More showers and isolated thunderstorms are expected over much of the interior Saturday, and over much of the southern and eastern interior Sunday. ARCTIC SLOPE AND BROOKS RANGE... Areas of fog near the coast during the late night and early morning hours, otherwise no significant weather expected through Sunday. Warm temperatures in the interior with highs as high as the low to mid 70s. WEST COAST... No significant weather expected through Sunday. Some coastal areas may see areas of fog. Coastal Hazard Potential Days 3 and 4...None. && .FIRE WEATHER... Some warming is expected in the interior over the weekend...with highs approaching or reaching 80 in some northern interior areas. Minimum humidities could approach 30 percent in the northern interior. Minimum humidities in the southern interior likely to remain at 35 percent or above. && .HYDROLOGY... Additional rainfall amounts of 0.5 to 1 inch are expected in Denali and the lower Kuskokwim Valley today. Northern parts of the Upper Tanana Valley and Fortymile country may see up to 0.5 inch, with local amounts of 0.75 inch possible. Locally heavier amounts will be possible in Denali and the lower Kuskokwim Valley today, but the location of the amounts remains uncertain due to the convective nature of the precipitation. && .AFG WATCHES/WARNINGS/ADVISORIES... Small craft advisory for PKZ245. && $$ RF JUN 16
Southcentral and Southwest Alaska Forecast Discussion...CORRECTED National Weather Service Anchorage AK 1108 PM AKDT THU JUN 30 2016 Corrected extended discussion .ANALYSIS AND UPPER LEVELS... The upper levels are starting to look like a mixed bag of goodies. The ever present upper level low spinning south of the gulf is slowly weakening but is continuing to eject shortwaves around it. The first of these waves moved across Southcentral last evening. The next is to the Northwest of PAYA and is noted on upper level analysis as an enhanced bubble of moisture and as a wiggle in the upper level analysis. This wave will move across the ALCAN border and across the Copper River Basin this afternoon. As of 2130z(1:30pm AKDT), showers are already beginning to form. This easterly wave will wrap around the low and slide across the Anchorage and Kenai areas tonight. A much more potent wave is easily identified in water vapor imagery near 49N 141W. As is the case with nearly stationary lows and these easterly waves that get ejected around, timing and placement has been a challenge. This strong wave is now progged to shift east and impact SE AK and BC. Farther west, a ridge between the Gulf low and a weakening Bering low is becoming pinched off as it retreats into the interior of Alaska. A strong upper level jet remains well south of the forecast area. At the surface, progress is being made on moving the nearly stationary low out of the gulf. A stalled out front stretches from a low in the Bering and southeast across the Akpen. && .MODEL DISCUSSION... All models are in pretty good agreement in the short term today. As briefly touched on in the analysis...the upper level low in the Gulf will shift east into the weaken. All of the models have varying levels of agreement with the shortwave strength and timing moving around the lows. The biggest trend from yesterday was slowing down the timing of the onset of the biggest rainmaker over Anchorage. The latest 18z runs of the NAM and GFS are showing a 9-12z time frame while the HRRR is hinting at an early start, between 5 and 6z. Judging by past performance of the HRRR and how poorly the major models play temporally, confidence in timing is low. However, all models are consistent with bringing in a healthy amount of rain across the region. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)... Increasing mass ascent ahead of a low amplitude short wave trough over the Western Yukon and Eastern Copper Basin is beginning to manifest itself as increasing convective showers across the region. As the shortwave propagates west tonight, showers will begin to congeal into a large area of stratiform rain which will impact all of Southcentral tonight with brief periods of heavy rainfall. The heaviest axis of rain will likely occur across the Copper Basin into the Mat-Su Valleys, although areas along the Kenai and into Anchorage will also see the potential for brief heavy rains overnight. Thunderstorms have formed already along the Kenai Range, and they will also be possible along the Talkeetnas and Alaska Range as well as along the Chugach in the evening. The shortwave trough will elongate and quickly move west Friday, with most rain moving into Southwest Alaska by the afternoon. Showers will develop in the afternoon behind the main low, but these will be mainly along mountains and rather limited given lack of instability. Saturday will be warmer as broad cyclonic flow sets up over the region, with more afternoon showers but slightly warming temperatures. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... The upper level low over the Gulf continues to bring easterly flow with embedded shortwaves over Southwest Alaska. This combined with the unstable environment is helping to kick off thunderstorms over the area through Friday. The most likely times for thunderstorms are during peak heating and as the shortwaves move through. The shortwaves look to move through this evening, Friday morning and Friday evening. Friday will also see heavier rain from the Kuskokwim Valley south towards Bristol Bay and east towards the Alaska and Aleutian Ranges. Saturday will see a lesser chance for thunderstorms with the most likely area over the Kuskokwim Vally but rain will still be likely from the valley through Bristol Bay. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)... A broad low over the Western Aleutians will last through the weekend slowly tracking east and bringing rain to the area. Areas from the Alaska Peninsula through the Pribilof Islands will be under the effects of weak ridging providing more fair conditions than areas to the west. && .LONG TERM FORECAST (Days 3 through 7)... On Sunday, the upper level pattern looks to grind to a halt from the easterly flow of weak disturbances to a much more chaotic movement. This will be due to the departure of the upper level low towards the Panhandle by Sunday morning, with no larger scale features following it. Thus, with everything being weak, any precipitation that develops Sunday over southern mainland Alaska will be scattered and weak. The persistence of a mid-level unstable layer over much of the area will result in some convection popping up with any showers that develop with enhanced lift, likely from topographic enhancement. For the Independence Day holiday, a strong upper level trough will dig southward across the eastern Bering. Ridging will build east of it across the Gulf. However, the models are in disagreement with how quickly the ridge builds, and where the trough axis sets up over the Bering. Currently, the models agree enough for the 4th of July to suggest a return to southwesterly winds in the upper levels. Since the disturbances depicted in the models all remain weak, the weather looks similar to Sunday at this point for much of mainland Alaska. Active weather should persist for much of southern Alaska into midweek as the trough over the Bering moves into mainland Alaska. However, the model differences and associated forecast uncertainty only compound with time concerning how quickly and in what form (open trough or cutoff low), the troughing moves east. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...NONE. MARINE...NONE. FIRE WEATHER...NONE. && $$ SYNOPSIS AND MODEL DISCUSSION...SS SOUTHCENTRAL ALASKA...JA SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK LONG TERM...JW