Area Forecast Discussion
Issued by NWS Pocatello, ID

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
000
FXUS65 KPIH 240908
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
308 AM MDT SUN APR 24 2016

.SHORT TERM...TODAY THROUGH TUESDAY NIGHT. AN CLOSED UPPER LEVEL
LOW PRESSURE SYSTEM IS CURRENTLY DRIFTING EASTWARD OVER CENTRAL
WYOMING AT THIS TIME. A WEAK DISTURBANCE ROTATING AROUND THE
BACKSIDE OF THE LOW COMBINED WITH ELEVATED ATMOSPHERIC MOISTURE
CONTENT AND FAVORABLE UPSLOPE FLOW IS RESULTING IN WIDESPREAD
SHOWERS FOR AREAS ALONG AND EAST OF THE I-15 CORRIDOR. MUCH OF THE
PRECIPITATION IS FALLING AS RAIN BELOW 7000 FEET WITH SNOW SHOWERS
ABOVE 7000 FEET. AT THIS TIME ROAD SURFACE TEMPERATURES ARE TOO
WARM FOR SLUSH TO FORM...BUT COULD CERTAINLY SEE SOME SLUSH ON
AREA PASSES OVER THE EASTERN HIGHLANDS AS THE OVERNIGHT
PROGRESSES...WITH ANY SLUSH MELTING DURING THE MID-MORNING HOURS.
RAIN AND SNOW SHOWERS WILL CONTINUE OVER THE EASTERN HIGHLANDS
THROUGH THE DAY. SHOWERS WILL BECOME INCREASINGLY COMMON ACROSS
THE CENTRAL MOUNTAINS DURING THE AFTERNOON DUE TO THE COMBINATION
OF AN INCREASE IN MOISTURE ASSOCIATED NEXT APPROACHING SYSTEM AND
THE DEVELOPMENT OF FAVORABLE SOUTHWESTERLY UPSLOPE FLOW.

THIS NEXT SYSTEM WILL MOVE ASHORE ACROSS THE PACIFIC NORTHWEST TONIGHT
AND SWING THROUGH NORTHERN NEVADA AND UTAH MONDAY AND TUESDAY.
THIS TRACK PLACES SOUTHERN IDAHO IN A FAVORABLE REGION FOR
ENHANCED PRECIPITATION. PRECIPITATION IS EXPECTED TO GRADUALLY
EXPAND EASTWARD ACROSS THE NEVADA AND UTAH BORDER REGION MONDAY
MORNING WITH WIDESPREAD SHOWERS...LOCALLY HEAVY AT
TIMES...DEVELOPING ACROSS ALL OF SE IDAHO BY AFTERNOON.
NORTHEASTERLY FLOW WILL FOCUS PRECIPITATION ACROSS THE SOUTHERN
HIGHLANDS...AND NORTHEAST WINDS MAY BECOME BREEZY TO OCCASIONALLY
WINDY ACROSS ALL OF SE IDAHO. SNOW LEVELS WILL GRADUALLY DROP
THROUGH THE DAY MONDAY...WITH THE LOWEST SNOW LEVELS CLOSER TO THE
LOW ACROSS THE UTAH BORDER REGION. THIS IS WHERE SNOW
ACCUMULATIONS MAY PILE UP TO AROUND ONE FOOT...FOCUSED ON THE
ALBION MOUNTAINS/SAWTOOTH NATIONAL FOREST HIGHLANDS. 3 TO 8 INCHES
OF SNOW WITH LOCALLY HIGHER AMOUNTS IS CURRENTLY EXPECTED ABOVE
6500 FEET ACROSS MUCH OF THE REMAINDER SE IDAHO WHICH MAY CAUSE
SOME SLUSH-COVERED PASSES...PARTICULARLY OVERNIGHT MONDAY INTO
TUESDAY MORNING. ADDITIONAL RAINFALL ASSOCIATED WITH THIS NEXT
SYSTEM WILL CONTINUE TO CAUSE RISES AND INCREASED STREAMFLOW ON
AREA RIVERS ALONG WITH PONDING OF WATER IN SOME AREAS. AD/HEDGES

.LONG TERM...WEDNESDAY THROUGH SUNDAY NIGHT. ECMWF AND GFS SHOWING
MINOR DIFFERENCE IN THE PLACEMENT OF THE UPPER LOW OVER THE WEST ON
WED...HOWEVER THE RESULT IS SIMILAR. SCATTERED SHOWERS OVER THE MTNS
WITH A LITTLE LESS COVERAGE OVER THE VALLEYS...THEN DIMINISHING WED
NIGHT. THE UPPER LOW MOVES TO THE SOUTHERN GREAT BASIN BY THU
MORN...WITH A REPEAT OF THE PRECIP PATTERN THU AND THU NIGHT. BY
FRI...THE UPPER LOW BECOMES DISORGANIZED AND MOVES OFF TO THE EAST.
IT WILL STILL HAVE ENOUGH INFLUENCE TO SET OFF SCATTERED SHOWERS
MAINLY FRI AFTN...THEN DIMINISHING AGAIN FRI NIGHT. ON SAT...THE
MODELS DIVERGE. THE GFS PLACES AN UPPER RIDGE OVER THE NORTHERN
ROCKIES INTO THE GREAT BASIN. THE ECMWF SHOWS A SPLIT FLOW UPPER
TROF PATTERN WITH A CLOSED LOW OVER THE CA/NV/AZ BORDER AREA.
NATURALLY, THE GFS IS MUCH DRIER THAN THE ECMWF. WILL CARRY MAINLY
ISOLD SHOWERS SAT AND SAT NIGHT GIVING A LITTLE MORE CONFIDENCE IN
THE ECMWF. BOTH MODELS GENERATE ISOLD SHOWERS OVER THE CENTRAL MTNS
AND EASTERN HIGHLANDS ON SUN...BUT FOR DIFFERENT REASONS. SUN NIGHT
BECOMES DOMINATED BY UPPER RIDGING...SO WILL GO WITH A DRY FCST.
HEDGES


&&

.AVIATION...SHOWERS EXPECTED TO CONTINUE THRU THE MORN OVER THE
EASTERN HALF OF THE FCST AREA...WITH IFR CIGS. CONDITIONS IMPROVE BY
AFTN AND CONTINUE THRU TONIGHT. VFR CONDITIONS EXPECTED THRU TONIGHT
AT KSUN AND KBYI. HEDGES


&&

.PIH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.