Weather Service Report


180 
FXUS66 KMFR 232144
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
244 PM PDT Fri Jun 23 2017

.DISCUSSION...Very hot and dry conditions today through Sunday will 
be followed by a chance for thunderstorms late Sunday into 
Monday. This magnitude and duration of hot weather in June has not
been observed in the Rogue Valley since the 1960s and will pose a
threat to public safety. Additionally, the thunderstorms that 
follow the heat could result in new wildfires in the forecast 
area.

The Southern Oregon coast near Brookings, which has experienced 
temperatures in the 80s the past few days, is now seeing more normal 
temperatures in the 60s as a coastal surge of cooler air and clouds 
moves south to north. It will take until Sunday to really cool down 
in the North Bend area as the surge slowly moves up the coast. We
have increased temperatures for North Bend for Saturday based on 
the latest guidance and the understanding that guidance can 
underforecast high temperatures in these highly anomalous 
situations. For most inland areas, the heat will peak on Saturday.
Daily Record high temperatures are possible for several locations
on Saturday and Sunday. Substantial cooling won't occur until 
Monday when readings dip to only 10 degrees above normal, compared
to the 25 degrees above normal that are expected over the 
weekend. Heat Advisories and Excessive Heat Warnings have been 
issued for most inland areas west of the Cascades for the weekend.
We want to emphasize some safety tips because over the past 30 
years, more weather-related fatalities have occurred due to heat 
compared to any other weather. Here they are:

* Beat the heat, check the backseat. Never leave people or pets in
  vehicles. 
* Rivers are dangerously cold and have strong currents. Wear a
  life jacket if swimming. 
* Monitor older adults, young children and those who are sick.
* Take plenty of rest breaks in shade or air conditioning.
* Drink water before, during and after activities.

As is typical with any waning of a heat wave, the upper ridge of 
high pressure pushes east, moisture and instability move into the 
forecast area, and thunderstorms are possible as the area 
transitions to cooler conditions. This happens on Sunday and 
Monday as moisture and energy are introduced into the forecast 
area from the south and west. Of particular interest is upper 
level instability present on Sunday night from the Cascades 
westward, bringing the potential for nighttime thunderstorms. 
Often storms at night have less rainfall than afternoon storms, 
and this can result in a better chance for new fire starts. Fire 
Weather Watches have been issued to account for the chance of new 
fire starts due to lightning. 

Monday will feature gusty west winds, especially east of the 
Cascades, as the cooler air mass enters the forecast area. 
Temperatures will actually reach near normal readings by Tuesday and 
this should continue for most of the week.

&&

.AVIATION...23/18Z TAF CYCLE...VFR conditions will continue at all 
inland terminals through the TAF period. There appears to be a good 
chance for MVFR visibility in light fog to redevelop at OTH after 04z 
this evening and worsen some toward 12z. MTS/Wright

&&

.MARINE...Updated 200 PM Friday, 23 June 2017...The thermal trough 
will slide inland, allowing southerly winds and fog to surge up the 
coast through tonight. The south winds should reach Cape Blanco by 
Saturday afternoon, then spread north to Florence by Saturday 
evening. Until then, residual steep seas will continue to produce 
small craft advisory conditions for almost all areas, with very 
steep and hazardous seas expected south of Cape Blanco through this 
evening. Relatively calm conditions are forecast for early next 
week, then the thermal trough is expected to return by midweek.
-BPN

&&

.FIRE WEATHER...Extremely hot, dry weather conditions today through 
the weekend will help to dry fuels and set the stage for possible 
fire starts as thunderstorms develop later Sunday into Monday. While 
heavier fuels are still wet and do not necessarily support fire 
spread or growth, finer fuels are approaching seasonal dryness 
levels. Furthermore, there is the potential for considerable 
lightning in the mountains and northern east side Sunday afternoon 
through Monday afternoon as well as some chance for nocturnal storms 
even over the west side Sunday night. In addition, breezy winds are 
expected Monday afternoon and Tuesday. As a result, we will be 
issuing a fire weather watch for parts of our area primarily for the 
potential of increased initial attack activity. -Wright

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...     Fire Weather Watch from Monday morning through Monday evening 
     for ORZ625. 
     Heat Advisory from 11 AM Saturday to 8 PM PDT Sunday for 
     ORZ023>028. 
     Excessive Heat Warning from 11 AM Saturday to 8 PM PDT Sunday 
     for ORZ023>028. 
     Fire Weather Watch from Sunday afternoon through Monday 
     afternoon for ORZ621-623. 
     Fire Weather Watch from Sunday afternoon through Monday morning 
     for ORZ620-622. 
     Fire Weather Watch from Sunday afternoon through Monday evening 
     for ORZ624. 

CA...Heat Advisory from 11 AM Saturday to 8 PM PDT Sunday for 
     CAZ080-081. 
     Excessive Heat Warning from 11 AM Saturday to 8 PM PDT Sunday 
     for CAZ080-081. 
     Fire Weather Watch from Sunday afternoon through Monday 
     afternoon for CAZ280. 

Pacific Coastal Waters...Small Craft Advisory until 11 PM PDT this evening for 
     PZZ350-356-370-376. 
     Small Craft Advisory for hazardous seas from 11 PM this evening 
     to 5 PM PDT Saturday for PZZ350-356-370-376. 
     Hazardous Seas Warning until 11 PM PDT this evening for PZZ376. 

$$

NSK/NSK/TRW

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Western Regional Climate Center, wrcc@dri.edu