An upper level low digging southward across Southwest Alaska, brought moist flow off the Gulf into Southcentral on southeasterly winds. This brought higher than normal rainfall to the northern and western Susitna Valley.
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The episode as NWS AFC wrote it up.
An upper level low digging southward across Southwest Alaska, brought moist flow off the Gulf into Southcentral on southeasterly winds. This brought higher than normal rainfall to the northern and western Susitna Valley.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Anchorage, AK wrote its last area forecast discussion before the first event at Aug 14, 2:47 AM AKST, 2 hours 23 minutes earlier.
Southcentral and Southwest Alaska Forecast Discussion National Weather Service Anchorage AK 347 AM AKDT Tue Aug 14 2018 .ANALYSIS AND UPPER LEVELS... There is a finger of the jet in the Central Bering but the main jet core spans from the North Pacific to Southeast Alaska. On satellite imagery there is a broad cloud shield spanning across Southwest and Southcentral Alaska. There is a second upper level disturbance over the Central Bering. At the surface, the low is northeast of Bethel with a value of 1001 mb. This has been a slow moving low. As such, the pressure gradient remains enhanced over much of Southwest Alaska and Kodiak. The latest ASCAT/advanced scatterometer pass has detected gale force winds in Bristol Bay and Kuskokwim Bay. The radars at Bethel, King Salmon and Kenai continue to be active this morning. && .MODEL DISCUSSION... The GFS and the ECMWF are in fair agreement depicting the progression of the synoptic features through 48 hrs. The area of contention is related to movement of lingering moisture through southwest and southcentral. By 00z Thursday both the GFS and the ECMWF have a negatively tilted trough near Kodiak, however the ECMWF is slightly more bullish bringing this feature up the Cook Inlet and then shifts it into the Gulf Of Alaska. Given the vagaries of the models, the forecast confidence is slightly below normal. && .AVIATION... PANC...The remnants of a low pressure system will continue to bring low and midlevel clouds to PANC. The current thinking is that ceilings will remain VFR. However, there is a possibility that the cigs will temporarily drop to MVFR. The 11z observation detected a scattered layer at 026. && .SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3)... A couple more short-wave will cross Southcentral through tonight, continuing to bring periods of rain or showers across much of the region. With persistent south to southwest low level flow, the favored areas for steadier rain and higher rainfall amounts remain the same; the northern to eastern Susitna Valley, Matanuska Valley, and across the Talkeetna Mountains up to the Denali Highway and south side of the Alaska Range. With the additional rainfall, expect rivers and streams in the Susitna River Basin to continue to rise to around bankfull. Based on rises overnight, the highest potential to experience some minor above bankfull flooding includes Montana and Willow Creeks. On Wednesday a digging trough over the eastern Bering will lead to development of a weak downstream ridge over Southcentral. This certainly won't be strong enough to end all precipitation, but shower activity will diminish and there should be some breaks of sun. The ultimate impact of the trough coming from the Bering Sea remains highly uncertain. Thus, once again have stuck with the inherited forecast which includes a broad-brush chance of showers Wednesday night into Thursday. && .SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)... Low pressure over Aniak this morning will continue to weaken today as it drifts slowly toward the Alaska Range. As it does, the gusty west to northwest winds along the back side of the low will begin to wane. The steady rainfall over much of the Southwest will also diminish in intensity and lift to the north today. This will help keep areas around Bristol Bay drier today, but clouds will remain due to a persistent onshore flow. A trough moving south along the Bering coast will develop a weak area of low pressure associated with a stalled out front west of the Kuskokwim Delta. This system will phase with another weak trough sliding across the southern Bering tonight. Models are still divergent in their solutions after this, but the general consensus is for the low to weaken and drift south. Precipitation associated with the low, regardless of model solution, will be limited to some shower activity along the mountains and across Bristol Bay from King Salmon south. Wednesday will also feature much lighter winds area- wide. Much of the same conditions persist into Thursday, with areas of scattered showers, mainly confined to the higher elevations. A few scattered showers may linger into Friday, especially over the AKPEN. Otherwise, it should remain rather dry with light winds across the rest of Southwest Alaska. && .SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)... Conditions across the eastern Bering will remain generally cloudy and unsettled through Thursday as a weak trough and developing low pressure system slides slowly toward the Alaska Peninsula. Gusty westerly winds across the eastern Bering will diminish in intensity this evening as the low over Southwest Alaska continues to weaken and drift east. High pressure developing over the central Aleutians will build northward across much of the central and western Bering through Wednesday. The next low and associated front move into the far western Bering towards Shemya and Attu on Wednesday. This system will then track south of the Aleutians on Thursday as high pressure remains anchored over the western and central Bering. && .LONG TERM FORECAST (Thursday night through Sunday night)... The extended forecast begins with the remnants of the upper low pressure, which is currently in the northern Bering Sea. Deterministic models are ranging in solutions from the northern Gulf through the tip of the Alaska Peninsula, but eventually consolidate a low center somewhere south of the Alaska Peninsula. The upper low and it's front will be the focus for active weather through the weekend. No matter the position of the surface low, guidance agree on it being a relatively strong system. Most of the mainland will be dry and seasonable as far as temperatures go, until the front reaches the area. The front will approach Kodiak Island on Saturday, likely a solid small-craft front, with a chance to reach into the gale-force range. The front and more and it's precipitation should spread up to the north Gulf coast on Sunday along with a round of gap-driven winds in the same area. && .AFC WATCHES/WARNINGS/ADVISORIES... PUBLIC...None. MARINE...138. && SYNOPSIS AND MODEL DISCUSSION...PJS SOUTHCENTRAL ALASKA...SEB SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...TM LONG TERM...ML
The national radar mosaic for the moment the first event began.
1 flood. Local standard time, as filed.
The river gauge on the Yentna River at Lake Creek went into minor flood stage for a brief period on August 14th. McDougall's Lodge Cabins were evacuated due to flooding water.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Alaska in 2018Every state in 2018This day in weather historyWarnings in Alaska, August 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 783049.