Marine Weather and Tide Forecast for Boise City, ID
 | Sunrise 6:19 AM Sunset 9:02 PM Moonrise 9:43 PM Moonset 5:28 AM |
7 Day Forecast for Marine Location Near Boise City, ID
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FXUS65 KBOI 131555 AFDBOI
Area Forecast Discussion National Weather Service Boise ID 955 AM MDT Tue May 13 2025
DISCUSSION
Showers associated with an upper low centered over the area this morning will expand in coverage through the afternoon. Marginal instability will support isolated thunderstorms this afternoon, mainly in SW Idaho near the core of the low. Some of the storms may produce brief heavy rain, small hail, and gusty winds to around 35 mph. No updates.
AVIATION
Mainly VFR. Scattered showers moving S-SE today into Wed. Isolated thunderstorms this afternoon/eve may create localized MVFR/IFR conditions. Mountain obscuration in low clouds/showers. Snow levels: 6-7k feet MSL. Surface winds: W-NW 10-20 kt with gusts 25-30 kt, decreasing to 5-15 kt tonight...except remaining strong from MUO to KTWF/KJER. Winds aloft at 10kft MSL: N to NW 10-25 kt.
KBOI...VFR. A 60% chance of showers late morning and afternoon.
Showers will be capable of brief MVFR ceilings, 30 kt outflow winds, and a threat of lightning (15% chance). Favored time for lightning will be 13/20Z to 14/00Z. Winds NW around 15 kt with afternoon gusts 25 kt, decreasing to around 10 kt by sunset.
PREV DISCUSSION
SHORT TERM
Today through Thursday night
As an upper low pressure system moves overhead, showers and thunderstorms will develop over SE Oregon and Idaho this afternoon. Thunderstorms have the best chance of formation over terrain, but a stray storm could drift into the lower elevations. There may be some limiting factors for proper convection: PWs below 50th percentile, and moist adiabatic lapse rates in the effective layer will limit CAPE. Outflow gusts are possible outside of stronger showers and storms, but DCAPE values generally less than 400 J/kg and HRRR forecast wind gusts suggest peak outflows may reach 40 mph. Still strong, but much less than what has been possible the previous few days. Snow levels are around 6kft MSL during precipitation, so minor accumulation (up to 3") is possible across higher terrain. Snow accumulation is most likely in the Boise Mountains Tuesday afternoon. The low exits eastward on Wednesday, with decreasing precipitation chances but still enough for isolated showers and storms Wednesday afternoon. With the low overhead/exiting, general gusts of 25 to 35 mph are expected across open terrain Tuesday/Wednesday afternoons. A very weak and brief ridge moves in behind the low for Thursday.
While it was previously forecast to warm us up close to normal for this time of year, it has weakened enough that temperatures stay about 5 degrees below normal.
LONG TERM
Friday through Tuesday
A weak upper level trough will move through early Friday, leading to a chance of showers mainly in the higher terrain on the Idaho side. Any rainfall will be fairly light for this time of year. There is a slight chance of thunderstorms in extreme SE Owyhee and southern Twin Falls counties.
Saturday, a stronger trough will move onshore, with significant disagreement on the location of a closed upper low that is expected to form Saturday afternoon. Some models have the closed low along the CA-OR border, while others have it as far north as Seattle. The location will have important implications for moisture transport and convective potential. At this time, ensemble mean seems like the way to go, so stuck with NBM guidance on precipitation and thunder potential. The chance of rain reaches its highest level of the long term period Saturday afternoon into the evening (60-80%), with thunderstorms favored over the southern portion of the area in the afternoon and in the southeast Saturday evening. This low should push a cold front through Saturday night into Sunday morning, and after highs just a few degrees below normal Friday and Saturday, Sunday should see highs 5-10 degrees below normal. The chance of rain decreases from west to east Saturday night and Sunday, with a slight chance to chance remaining only on the Idaho side Sunday afternoon. Thunderstorm chances move to the east Sunday, generally from just east of McCall to Boise to central Owyhee County.
The trough axis will move off to the east Sunday night into Monday morning, and enough moisture and cold air aloft will remain to warrant 20-40% chance of showers over the higher terrain generally east of McCall Monday, with even lower chances farther east Tuesday.
Thunderstorm potential should be limited to our far southeast Monday, and gone altogether Tuesday. Temps are forecast to warm back up to near normal by Tuesday. Winds will increase in Oregon Saturday, then become even stronger as the trough axis moves overhead and to our east Sunday. Gusts 30-35 mph are expected to be common across lower elevations Sunday into Sunday evening. Gusty winds will continue Monday and Tuesday, but are not expected to be as strong as Sunday.
BOI WATCHES/WARNINGS/ADVISORIES
ID...None.
OR...None.
Area Forecast Discussion National Weather Service Boise ID 955 AM MDT Tue May 13 2025
DISCUSSION
Showers associated with an upper low centered over the area this morning will expand in coverage through the afternoon. Marginal instability will support isolated thunderstorms this afternoon, mainly in SW Idaho near the core of the low. Some of the storms may produce brief heavy rain, small hail, and gusty winds to around 35 mph. No updates.
AVIATION
Mainly VFR. Scattered showers moving S-SE today into Wed. Isolated thunderstorms this afternoon/eve may create localized MVFR/IFR conditions. Mountain obscuration in low clouds/showers. Snow levels: 6-7k feet MSL. Surface winds: W-NW 10-20 kt with gusts 25-30 kt, decreasing to 5-15 kt tonight...except remaining strong from MUO to KTWF/KJER. Winds aloft at 10kft MSL: N to NW 10-25 kt.
KBOI...VFR. A 60% chance of showers late morning and afternoon.
Showers will be capable of brief MVFR ceilings, 30 kt outflow winds, and a threat of lightning (15% chance). Favored time for lightning will be 13/20Z to 14/00Z. Winds NW around 15 kt with afternoon gusts 25 kt, decreasing to around 10 kt by sunset.
PREV DISCUSSION
SHORT TERM
Today through Thursday night
As an upper low pressure system moves overhead, showers and thunderstorms will develop over SE Oregon and Idaho this afternoon. Thunderstorms have the best chance of formation over terrain, but a stray storm could drift into the lower elevations. There may be some limiting factors for proper convection: PWs below 50th percentile, and moist adiabatic lapse rates in the effective layer will limit CAPE. Outflow gusts are possible outside of stronger showers and storms, but DCAPE values generally less than 400 J/kg and HRRR forecast wind gusts suggest peak outflows may reach 40 mph. Still strong, but much less than what has been possible the previous few days. Snow levels are around 6kft MSL during precipitation, so minor accumulation (up to 3") is possible across higher terrain. Snow accumulation is most likely in the Boise Mountains Tuesday afternoon. The low exits eastward on Wednesday, with decreasing precipitation chances but still enough for isolated showers and storms Wednesday afternoon. With the low overhead/exiting, general gusts of 25 to 35 mph are expected across open terrain Tuesday/Wednesday afternoons. A very weak and brief ridge moves in behind the low for Thursday.
While it was previously forecast to warm us up close to normal for this time of year, it has weakened enough that temperatures stay about 5 degrees below normal.
LONG TERM
Friday through Tuesday
A weak upper level trough will move through early Friday, leading to a chance of showers mainly in the higher terrain on the Idaho side. Any rainfall will be fairly light for this time of year. There is a slight chance of thunderstorms in extreme SE Owyhee and southern Twin Falls counties.
Saturday, a stronger trough will move onshore, with significant disagreement on the location of a closed upper low that is expected to form Saturday afternoon. Some models have the closed low along the CA-OR border, while others have it as far north as Seattle. The location will have important implications for moisture transport and convective potential. At this time, ensemble mean seems like the way to go, so stuck with NBM guidance on precipitation and thunder potential. The chance of rain reaches its highest level of the long term period Saturday afternoon into the evening (60-80%), with thunderstorms favored over the southern portion of the area in the afternoon and in the southeast Saturday evening. This low should push a cold front through Saturday night into Sunday morning, and after highs just a few degrees below normal Friday and Saturday, Sunday should see highs 5-10 degrees below normal. The chance of rain decreases from west to east Saturday night and Sunday, with a slight chance to chance remaining only on the Idaho side Sunday afternoon. Thunderstorm chances move to the east Sunday, generally from just east of McCall to Boise to central Owyhee County.
The trough axis will move off to the east Sunday night into Monday morning, and enough moisture and cold air aloft will remain to warrant 20-40% chance of showers over the higher terrain generally east of McCall Monday, with even lower chances farther east Tuesday.
Thunderstorm potential should be limited to our far southeast Monday, and gone altogether Tuesday. Temps are forecast to warm back up to near normal by Tuesday. Winds will increase in Oregon Saturday, then become even stronger as the trough axis moves overhead and to our east Sunday. Gusts 30-35 mph are expected to be common across lower elevations Sunday into Sunday evening. Gusty winds will continue Monday and Tuesday, but are not expected to be as strong as Sunday.
BOI WATCHES/WARNINGS/ADVISORIES
ID...None.
OR...None.
Link to 1 hour of 5 minute data for KBOI
Terminal Aerodrome Forecast (TAF) for KBOI
Wind History Graph: BOI
(wind in knots)
GEOS Local Image of Pacific Northwest
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