Southcentral and southwest Alaska forecast discussion 
National Weather Service Anchorage Alaska 
500 am akdt Wednesday Jun 19 2013 


Analysis and upper levels... 
early this morning an upper ridge is centering near the northwest 
coast and a closed low is moving west along the base approaching the 
tip of the Kenai Peninsula. A few showers have developed on the west 
side of the low along the western Gulf of Alaska and the Aleutian 
Range. A couple of lightning strikes were noted north of Iliamna. Two 
other low pressure centers...one near the Kamchatka peninsula and the 
other south of the Alaska Peninsula...are keeping low to middle levels 
clouds across the Bering and Aleutians. Patchy fog continues along 
eastern Bering. Light showers have moved off the coast near the 
Kuskokwim Delta. 


Model discussion... 
models are generally in good agreement through Friday morning and 
then begin to diverge in solutions. The lows near Kenai and the 
Alaska Peninsula will move off to the northwest through Friday. A 
storm system will move toward the western Aleutians Thursday and 
continue east nearing the Alaska Peninsula on Saturday. The forecast 
was mainly updated with the NAM and European model (ecmwf) through Saturday. 


Short term forecast... 
southcentral Alaska... 
temperatures will begin to slowly moderate today. Gusty conditions 
are expected to increase in the afternoons through Friday along 
Turnagain Arm and higher elevations and across areas that typically 
experience sea breezes. The low pressure system in the Gulf will 
bring showers today and tonight across the western Gulf and then 
taper off by Thursday morning. Snow melt has caused water levels to 
rise for the Matanuska and little Susitna rivers. A Flood Advisory is 
out through Thursday for the Matanuska. The Flood Advisory for the 
little Susitna has been cancelled this morning as the river has 
peaked and water levels are now decreasing. A Flood Watch remains in 
effect for yentna river at Lake Creek through Thursday. Gusty winds 
are expected to develop this afternoon across the Copper River and a 
red flag will be issued for strong winds this morning. 


Southwest Alaska... 
scattered showers will continue to develop across southwest Alaska 
today. Instability around the cold upper low will help to initiate 
thunderstorms near the core center...as a few strikes have reported 
this morning along the Aleutian Range. Thunderstorms will diminish 
later tonight and showers will taper off on Thursday as the low moves 


Into the northern Bering. Another storm system will approach the 
southwest coast on Saturday. 


Aleutians/Bering Sea... 
periods of rain across the eastern Aleutians and Alaska Peninsula 
will continue through much of Thursday as low pressure moves from the 
south and east. Another storm system will move into the western 
Aleutians Thursday night and continue and eastward path. Strong winds 


With this storm increase over Shemya tonight. This storm system 
should be monitored for updates as it looks to remain strong along 
the Aleutians into Saturday. 


Long term forecast... 
the forecast beyond Friday night remains low confidence as models 
continue with inconsistency from run to run. The upper level low may 
bring a wetter pattern for the Gulf and southern Alaska this weekend 
into the beginning of next week. If this system takes a more 
southerly track...warmer temperatures will return as upper ridging 
build into east Alaska. 


Aer/alu...watch/warning summary 
public...none. 
Marine...gales 175 a76. 
Fire weather...red flag warning 141. 


Kh Jun 13