Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 201958
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
158 PM MDT SUN JUL 20 2014

.DISCUSSION...MONSOON PUSH STARTING TO MAKE ITS WAY NORTH INTO
IDAHO THIS AFTERNOON AHEAD OF LOW SPINNING IN NEVADA/CALIFORNIA.
INITIAL CLOUD SURGE AT NORTH END OF LOW HAS PUSHED INTO AREAS
MAINLY SOUTH OF INTERSTATES 84/86 WITH RADAR INDICATING WEAK
RETURNS MAINLY AS A RESULT OF MID LEVEL STRATO-CUMULUS DECK. STILL
A POTENTIAL FOR DEVELOPMENT SOUTH HALF OF FORECAST AREA LATE THIS
AFTERNOON BUT BEST DEVELOPMENT SURGES NORTH THROUGH FORECAST AREA
THIS EVENING AND OVERNIGHT AS STRONG SHORTWAVE MOVES INLAND INTO
THE PACNW. PWAT LEVELS INCREASE TO AROUND ONE INCH ACROSS MOST OF
EAST IDAHO BY LATE EVENING. MODEL SOUNDINGS SHOW THREAT OF 40-50
MPH WIND GUSTS THIS EVENING BUT SHEAR INCREASES OVERNIGHT INTO
TUESDAY ESPECIALLY MID LEVELS FOR CONTINUED THREAT OF STRONGER
GUSTS. PACIFIC SHORTWAVE CROSSES PANHANDLE INTO NORTHERN PLAINS
MONDAY LEAVING TAIL OF SHORTWAVE DRAPED INTO EAST IDAHO. HIGH PWAT
VALUES PERSIST INTO TUESDAY WITH STRONG MU- CAPE ESPECIALLY EARLY.
CONCERN THAT CLOUD COVER FROM OVERNIGHT/EARLY STORMS COULD LIMIT
INSTABILITY BUT THREAT STILL ENOUGH FOR STRONG WINDS AND OF COURSE
LOCALLY HEAVY RAINS. MOVEMENT OF STORMS SHOULD BE QUICK ENOUGH TO
LIMIT SLOW- MOVERS AND THREAT FOR FLASH FLOODING SO WILL FOREGO
FLASH FLOOD WATCH FOR NOW. THREAT WILL REMAIN GUSTY WINDS AND
HEAVY RAIN.

RIDGE AMPLIFIES CENTRAL ROCKIES/4 CORNERS REGION TUESDAY INTO
WEDNESDAY. MOISTURE STREAM PUSHES SLIGHTLY NORTHWEST WITH FOCUS
FOR CONVECTION SHIFTING TO THE CENTRAL MOUNTAINS AND DIVIDE. DRY
SLOT PUSHES INTO REMAINDER OF REGION BUT SMALL SLIVER OF MONSOON
FLOW EXTENDS INTO SOUTHEAST CORNER AROUND THE HIGH TUESDAY NIGHT.
HAVE LEFT POPS DRY IN THIS REGION FOR NOW BUT WILL BE SOMETHING TO
KEEP AN EYE ON. TEMPS REBOUND INTO THE 90S MOST AREAS WITH
STRONGER SOUTHERLY FLOW. PACIFIC LOW PUSHES INLAND WEDNESDAY AND
CROSSES INTO ALBERTA EARLY THURSDAY. TRAJECTORY OF LOW PULLS MUCH
DRIER AIR MASS ACROSS THE REGION BUT ALSO DROPS COLD FRONT THROUGH
THE REGION THURSDAY. UPPER HIGH SHIFTS WEST TOWARD THE GREAT BASIN
WITH NORTHWEST FLOW IN PLACE THURSDAY NIGHT THROUGH THE REMAINDER
OF THE FORECAST PERIOD WITH DRY CONDITIONS AND GENERALLY
SEASONABLE TEMPS. DMH


&&

.AVIATION...GENERALLY VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD
BUT EXPECTING WIDESPREAD THUNDERSTORMS TONIGHT AND TOMORROW WITH
VCTS BEGINNING THIS AFTERNOON AND EVENING. CURRENTLY EXPECTING THE
BIGGEST THREAT OF THUNDERSTORMS AT TAF SITES TO BE 12Z MONDAY
THROUGH 21Z MONDAY. THESE THUNDERSTORMS WILL BE CAPABLE OF PRODUCING
HEAVY RAIN...GUSTY OUTFLOW WINDS AROUND 50 MPH AND FREQUENT
LIGHTNING. THUNDERSTORMS SHOULD BEGIN TO TAPER OFF AFTER 00Z TUESDAY.
EP


&&

.FIRE WEATHER...SATELLITE IMAGERY IS SHOWING MONSOON MOISTURE MOVING
INTO THE AREA TODAY VIA A SUBTROPICAL WAVE CURRENTLY IN CENTRAL
NEVADA. CURRENTLY EXPECTING SCATTERED THUNDERSTORMS TO BEGIN MOVING
INTO SOUTHERN PORTIONS OF IDAHO THIS EVENING...THEN SPREADING
THROUGH THE ENTIRE AREA OVERNIGHT...AND CONTINUING THROUGH MONDAY.
THERE WILL BE PLENTY OF MOISTURE ASSOCIATED WITH THESE THUNDERSTORMS
SO HEAVY RAIN WILL BE PRESENT...BUT SOME STORMS MAY BECOME CLOSE TO
SEVERE AND PRODUCE FREQUENT LIGHTNING AND GUSTY WINDS OF AROUND 50
MPH. DESPITE MIN RH VALUES MOSTLY IN THE 30S AND 40S ON MONDAY...THE
THREAT OF NEW FIRE STARTS AND RAPID FIRE GROWTH REMAINS...AND IS
CONFIRMED THROUGH COORDINATION WITH AFFECTED PARTNERS.
THEREFORE...HAVE EXTENDED THE AREA AND TIME OF CURRENT RED FLAG
WARNING. THE RED FLAG WARNING NOW INCLUDES ZONES 422 425 427 AND 410
FOR SCATTERED THUNDERSTORMS AND GUSTY WINDS TONIGHT THROUGH 9 PM
MONDAY. ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED IN THE CENTRAL
MOUNTAINS ON TUESDAY AS SE ID TRANSITIONS INTO A MOIST SOUTHWEST
FLOW THAT WILL FAVOR UPSLOPE AREAS. DRIER CONDITIONS ARE EXPECTED
WEDNESDAY AND BEYOND.
EP


&&

.PIH WATCHES/WARNINGS/ADVISORIES...
RED FLAG WARNING FROM MIDNIGHT TONIGHT TO 9 PM MDT MONDAY IDZ410.

RED FLAG WARNING UNTIL 9 PM MDT MONDAY IDZ427.

RED FLAG WARNING FROM 6 PM THIS EVENING TO 9 PM MDT MONDAY
IDZ422.

RED FLAG WARNING FROM 6 AM TO 9 PM MDT MONDAY IDZ425.

&&

$$







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