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Office: BOI

FXUS65 KBOI 102018

Area Forecast Discussion
National Weather Service Boise ID
218 PM MDT Wed Aug 10 2022

.SHORT TERM...Tonight through Friday night...Showers and isolated
thunderstorms continue to move through the forecast area this
afternoon, with a couple stronger storms noted over eastern
Oregon. Heavy rain remains possible over southwestern Idaho today
with precipitable waters of 1 to 1.5 inches as observed on the
morning upper air sounding. Small hail possible with storms, as
well as gusty winds. The moisture plume continues to shift east
today, with showers weakening overnight. Additional moisture pushes
expected the next couple of days, though water content is not
expected to be as significant as today and yesterday. Isolated
afternoon thunderstorms remain possible with gusty winds.
Temperatures will warm over the next couple of days, with values
returning to above normal levels by Friday.

.LONG TERM...Saturday through Wednesday...Upper level southwest flow
will continue through the weekend, as an upper level low moves to
our northwest. Models have dried out quite a bit for this weekend,
keeping precipitation mainly to our south and east. However, some
monsoon moisture will creep in on Saturday and Sunday afternoon,
bringing isolated rain showers and thunderstorms to the Boise
Mountains and near the ID-NV border. A ridge will retrograde into
the Intermountain West early next week and elevate temperatures to 5-
10 degrees above normal.


.AVIATION...Mostly VFR with scattered mid-level clouds. Scattered
showers/virga and isolated thunderstorm activity through tonight,
mainly in Baker County, OR and in southwest Idaho. Storms capable of
producing locally heavy rain and outflow gusts to 40 kt. Hot
afternoon temperatures will lead to high density altitude.

Surface Winds: generally variable 10 kt or less, except in Harney
County, OR this afternoon with S-SW 15-20 kt and in thunderstorms
with gusts to 40 kt. Winds aloft at 10k feet MSL: SE-SW 15-30 kt.






Office: PIH FXUS65 KPIH 102035 AFDPIH Area Forecast Discussion National Weather Service Pocatello ID 235 PM MDT Wed Aug 10 2022 .SHORT TERM...Today and Thursday. An extended period of active weather begins today as monsoonal moisture starts to move in from the southwest, with the overall setup still being an upper low off the Pacific Northwest coast and broad, upper ridge shifting further east over the central United States. Chances for scattered thunderstorms exist for the entire region, with convective initiation occurring further east as we head into tonight. The SPC has the entire state of Idaho in a general thunderstorm risk and the WPC has the majority of our CWA in at least a marginal risk (5% probability) of excessive rainfall for today, with approximately the western half of our CWA in a slight risk (15% probability) of excessive rainfall. Radar is currently showing weak returns across the CWA with greatest activity still further west. Current satellite imagery shows some breaks in cloud cover, which will help to further destabilize the atmosphere. The amount of heating we receive will affect the degree to which convection will be able to initiate this afternoon and evening. Moderate to heavy rainfall could create flooding concerns, especially across the southwestern portion of our CWA, with PWATS in excess of 1", increasing closer to 1.5" in the south central Idaho region as we head into the evening hours. HREF is indicating that it is likely for localized areas further west to receive over 0.25" of rainfall within a 6-hr. period through this evening, with most areas east of Pocatello seeing at least a tenth of an inch. Outside of convection, winds will be generally be 25 mph or less, but gusty outflow winds associated with stronger storms will be likely. Hi- res models are indicating sufficient shear this evening along with SBCAPE, MUCAPE, and DCAPE values increasing closer to 1,000 J/Kg as we head into late tonight. Tomorrow will be another active weather day with a brief break early morning through early afternoon and impacts shifting further east for tomorrow. Cropp .LONG TERM...Friday through Wednesday. The models are in fairly good agreement that the low off the Washington coast will migrate into the mean ridge position over Canada late Saturday-ish then shifting east through Canada while the associated monsoon moisture across SE Idaho gets shunted east of the area by Monday and Tuesday. The models suggest a continuation of fairly high Precipitable Water levels through Friday and thus have added a mention of the potential for heavy showers Friday afternoon also coinciding with the WPC Marginal Excessive Rain Outlook. The Blend of Models looks to hold on to a higher mention of precipitation potential into early next week which is not really in line with the model agreement cited above. Thus, have nudged the probability lower. Daytime highs generally run about normal for this time of year early on in the forecast period under the monsoon flow and then begin to push higher Monday through Wednesday as the monsoon moisture is gradually shunted east of the region. Huston && .AVIATION...VFR conditions forecast throughout the period with the potential for isolated degraded conditions associated with scattered showers and thunderstorms. Winds will generally not exceed 20 kt gusts, aside from the potential for gusty outflow winds. Showers and storms will increase through the afternoon and evening, with convection further east occurring later tonight. Tomorrow will be another active weather day with a brief break early morning through early afternoon tomorrow. Cropp && .FIRE WEATHER...The upper ridge has broken down and shifted east into Wyoming while a broad upper low remains positioned off the NW Oregon coast. This pattern has opened the door for a surge of monsoon moisture north across SRN Idaho. Regional radar was showing light radar returns (weak cells) lifting north through SRN Idaho early this afternoon and accompanying cloud cover may yet inhibit strong thunderstorm development across the region today. Further south, lifting north across NE Nevada, the cells look a little more vigorous and this may be associated with an embedded disturbance which could lift into the Twin Falls-Burley area by about 5 PM MDT this evening. The atmosphere is very supportive of heavy rain with thunderstorm activity today and this evening and thus no Red Flags have been issued due to the wet nature anticipated with these cells. The main thrust of convective activity looks to shift east across SE Idaho Thursday and Friday as the upper low migrates north off the Washington coast. Here again, the atmosphere and increasing daytime minimum humidity levels are expected to preclude the issuance of any Red Flag products due to the moist nature of the expected thunderstorm activity. As the low migrates into Canada and over the top of the ridge Friday and Saturday, the monsoon moisture should gradually get shunted further south and east across the SE mountains and then likely east of the region perhaps as early as Monday. The high looks to reload across the 4-corners region Monday through Wednesday awaiting another break down in the ridge to allow the moisture to surge north into Idaho. For now, temperatures look to push well above normal once again Monday through Wednesday. Huston && .AIR QUALITY...Recent fire activity has created adverse air quality conditions across the upper valley for which the Idaho DEQ has issued an Air Quality Advisory. This will likely be a day-to-day product issuance given the unpredictable nature of wildfire smoke production. Huston && .PIH WATCHES/WARNINGS/ADVISORIES... None. && $$