Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS65 KSLC 290401
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
901 PM MST WED JAN 28 2015

.SYNOPSIS...HIGH PRESSURE ALOFT ACROSS THE GREAT BASIN WILL SHIFT
EAST AHEAD OF THE NEXT DEVELOPING STORM SYSTEM LATE IN THE WEEK.
THIS RATHER MOIST STORM SYSTEM WILL IMPACT PRIMARILY CENTRAL AND
SOUTHERN UTAH LATE THURSDAY NIGHT THROUGH SATURDAY.

&&

.SHORT TERM (THROUGH 00Z SUNDAY)...HIGH PRESSURE ALOFT WILL SETTLE
IN ACROSS THE GREAT BASIN FOR LATER TONIGHT THROUGH MUCH OF THE
DAY THURSDAY. WEAK FLOW ALOFT WILL KEEP MUCH OF THE LOW-LEVEL
MOISTURE IN PLACE ACROSS THE FORECAST AREA AHEAD OF THE NEXT
DEVELOPING STORM SYSTEM FOR THE END OF THE WEEK.

THE UPPER LOW CURRENTLY NEAR 25/125 WILL PHASE WITH A WEAK
SHORTWAVE ALONG THE NORTHERN CALIFORNIA COAST TO FORM A WEAK
ELONGATED UPPER TROUGH CENTERED ALONG 120W THURSDAY. THIS TROUGH
WILL GRADUALLY EVOLVE INTO A BROAD CLOSED UPPER LOW FOCUSED ON THE
OLD LOW LATITUDE UPPER LOW CENTER POSITIONED ACROSS SOUTHEAST
CALIFORNIA/NORTHERN BAJA BY EARLY FRIDAY.

SUBTROPICAL MOISTURE TAPPED BY THIS UPPER LOW WILL FUEL A BROAD
AREA OF PRECIP ACROSS SOUTHERN UTAH BEGINNING LATE THURSDAY NIGHT.
THIS PRECIP WILL EXPAND NORTH ACROSS ALL OF SOUTHERN UTAH...AND
MUCH OF CENTRAL AND EASTERN UTAH ON FRIDAY. THE PARENT UPPER LOW
WILL MOVE LITTLE FRIDAY NIGHT/EARLY SATURDAY...LEADING TO
PROLONGED PERIOD OF LIGHT TO MODERATE VALLEY RAIN AND MOUNTAIN
SNOW INTO SATURDAY MORNING.

THE UPPER LOW WILL BEGIN A SLOW SOUTHWARD DRIFT INTO NORTHERN
MEXICO LATE SATURDAY IN RESPONSE TO HIGH PRESSURE ALOFT BUILDING
INTO THE NORTHERN/WESTERN GREAT BASIN. THE WIDESPREAD PRECIP
ASSOCIATED WITH THE LOW WILL FOLLOW THIS FEATURE SOUTH OUT OF THE
FORECAST AREA AFTER 00Z SUNDAY.

&&

.LONG TERM (AFTER 00Z SUNDAY)...RIDGE BUILDS IN FROM THE
NORTH BEHIND THE EXITING STORM SYSTEM WILL PUSH THE LAST OF THE
PRECIP OUT OF SOUTHERN UTAH SATURDAY EVENING. TEMPERATURES AT 700
MB WARM TO NEAR 0C OR BETTER ACROSS MUCH OF THE CWA SUNDAY
AFTERNOON WHICH SHOULD HAVE NO PROBLEM BEING REALIZED IN THE
MOUNTAINS BUT IS ALWAYS A CHALLENGE FOR THE VALLEYS AS AN
INVERSION WILL PLAY A ROLE IN KEEPING THE TEMPS DOWN SOME.
PROBABLY HAVE NOT GONE WARM ENOUGH BUT WILL HAVE TIME TO PUSH
UPWARDS AS THE WEEKEND APPROACHES.

THE RIDGE GETS FLATTENED BY A KIND OF ZONAL FLOW BY MONDAY WHICH
CONTAINS A COUPLE OF WEAK DISTURBANCES. THE GFS AND EC ARE SOMEWHAT
SIMILAR IN THE DEGREE OF COOLING AT 700 MB BUT THE EC IS ABOUT 2-3C
COLDER AT 500MB BY 18Z MONDAY MAKING IT THE MORE UNSTABLE MODEL YET
IT IS THE GFS THAT INDICATES SOME QPF ACROSS THE NORTHERN PORTION OF
THE CWA.  HAVE LEANED TOWARD THE GFS SOLUTION FIGURING THAT THERE
APPEARS TO BE ENOUGH INSTABILITY FOR A CHANCE OF LIGHT PRECIPITATION.
THIS ZONAL FLOW ON MONDAY CHANGES ORIENTATION TO MORE NORTHWEST AS
THE EASTERN PACIFIC RIDGE BEGINS TO BUILD TUESDAY THROUGH
WEDNESDAY. ANOTHER RIPPLE OR TWO MOVES THROUGH THIS NORTHWEST FLOW
WHICH SINKS FARTHER SOUTH INTO CENTRAL UTAH TUESDAY AFTERNOON AND
NIGHT. HAVE INCREASED THE POPS AND EXTENDED THEM A LITTLE FARTHER
SOUTH FOR THIS TUESDAY PERIOD AS THE GFS TREND HAS MORE MOIST
NORTHWEST FLOW ACROSS THE REGION. THE CANADIAN IS THE COLDEST OF
THE GLOBAL MODEL SOLUTIONS WITH MINUS 10C PUSHING IN ACROSS THE
NORTH. CHOSE THE GFS TO BASE TEMPERATURES AS IT WAS CLOSE TO THE
AVERAGE BETWEEN THE CANADIAN AND EC.

THE FINAL WAVE WEAKENS AS IT MOVES SOUTHEAST ACROSS THE CWA
WEDNESDAY SO PULLED BACK ON THE POPS A LITTLE FOR WEDNESDAY
AFTERNOON AS THE RIDGE BEGINS TO HAVE AN IMPACT ON AT LEAST THE
WESTERN PORTION OF THE CWA WHICH WILL SEE SOME STABILIZATION.

&&

.AVIATION...NORTHERLY FLOW IS EXPECTED TO REMAIN AT THE SLC TERMINAL
THROUGH MOST OF TONIGHT WITH A SWITCH TO SOUTHEAST NOT EXPECTED
UNTIL 10-12Z. OTHERWISE VFR CONDITIONS ARE EXPECTED THROUGH THE
VALID TAF PERIOD. THERE IS A 30 PERCENT CHANCE THAT CIGS BELOW
6000FT WILL REDEVELOP AT TIMES OVERNIGHT.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...NONE.
&&

$$

SHORT TERM...CONGER
LONG TERM...STRUTHWOLF
AVIATION...CHENG

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)

FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)



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