Larry,
In addition to the forecast, other issues are
(1) What is the condition of the trail?
(2) Is the Portal Road open? If so, where can I safely park?
(3) If I can drive up the Road to start my hike, what are the chances the Road will close during my hike (rockfall, mudslide,...)?
(4)Can I find satisfaction in hiking part of the way up the trail and enjoy the awesome scenery, but then turn around? (By the way, this is excellent training and acclimatization.) Maybe return later in the season.
(4) Does the group I am hiking with have a plan (agreed upon before the hike) for contingencies?
I have pushed the start of my hike over Kearsarge Pass back a day from Aug 9 to Aug 10 without disrupting my backcountry objectives. Can you delay your Mt Whitney hike, if the forecast remains unfavorable? On rec.gov Mt Whitney permits are regularly becoming available.
If the weather is unfavorable on Aug, 11 I will cancel. I'm not walking into deteriorating conditions!
A problem for us is when a day or two before the hike the weather forecast is "50/50."Then, perhaps those with marginal fitness, skills, equipment, enthusiasm should defer to a later date. Those who might cautiously start the hike are those who are fit, motivated, and are accustomed to and equipped for operating in adverse conditions (construction worker from Montana, longshoreman from Leningrad, SEKI backcountry ranger).
Let's see how things play out. I guarantee you we are not alone!
Jim