Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 142045
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
245 PM MDT MON APR 14 2014

.SYNOPSIS...HIGH PRESSURE ALOFT WILL CROSS THE REGION
TONIGHT...AHEAD OF A SERIES OF PACIFIC STORM SYSTEMS WHICH WILL
CROSS THE NORTHERN GREAT BASIN DURING THE MIDDLE OF THE WEEK.

&&

.SHORT TERM (THROUGH 00Z FRIDAY)...
WATER VAPOR LOOP SHOWS AN AMPLIFIED RIDGE ALONG THE WEST COAST.
AMDAR 400-250MB WIND OBSERVATIONS REVEAL A 80-90KT CYCLONICALLY
CURVED JET OVER THE EASTERN GREAT BASIN AND FOUR CORNERS REGION.
GOES/GPS/RAP/12Z RAOB INDICATE THE PRECIPITABLE WATER VALUE RANGES
BETWEEN 0.03" AND 0.25".

A COOL START THIS EVENING GIVEN THE DRY AIRMASS IN PLACE. HOWEVER
RAP 850-700MB SATURATED EQUIVALENT POTENTIAL TEMPERATURE AND
STREAMLINES DEPICT A WARM FRONT CROSSING THE STATE FROM SOUTHWEST TO
NORTHEAST OVERNIGHT. THIS WILL IN TURN CAUSE AN INCREASE IN
SOUTHERLY WINDS IN THE HIGHER TERRAIN AND A WARMING COLUMN SHOULD
SLOW THE TEMPERATURE DECLINE DURING THE LATER PORTION OF THE NIGHT.
STILL...CANNOT RULE OUT NEAR HARD FREEZE TEMPERATURES NEAR GREEN
RIVER AS BULK OF MID AND UPPER CLOUDS REMAIN FURTHER NORTHWEST
OVERNIGHT.

COLD FRONT SLIPS INTO NORTHWEST UTAH TOMORROW AFTERNOON...THOUGH
BULK OF COLD ADVECTION ALOFT IS DELAYED UNTIL LATER TUESDAY NIGHT.
SPOTTY SHOWERS CANNOT BE RULED OUT ACROSS THE NORTH DURING THE
HEATING OF THE AFTERNOON...THOUGH 15Z SHORT RANGE ENSEMBLES INDICATE
INSTABILITY WILL BE MEAGER. MORE OF A FACTOR WILL LIKELY BE AN
INCREASE IN WIND GUSTS ON EITHER SIDE OF THE SURFACE BOUNDARY.

SHOWERS INCREASE IN COVERAGE SOMEWHAT TUESDAY NIGHT WITH COLD
ADVECTION MOVING IN NEAR 700MB...THOUGH WITH THE COLD POOL ALOFT
SLIDING ACROSS WYOMING PROSPECTS FOR SIGNIFICANT ACCUMULATIONS ARE
LOW. DOWNSLOPE WINDS LIKELY WILL BE ENHANCED NEAR FAVORED LOCATIONS
OF EAST CENTRAL AND SOUTHERN UTAH TUESDAY NIGHT INTO WEDNESDAY
MORNING.

DIURNAL INSTABILITY WILL INCREASE COVERAGE OF SHOWERS AGAIN
WEDNESDAY...WITH THE ARRIVAL OF THE LEFT EXIT REGION OF THE UPPER
LEVEL JET AIDING. RIDGING BUILDS IN THURSDAY ALLOWING FOR CLEARING
AND WARMING CONDITIONS.

&&

.LONG TERM (AFTER 00Z FRIDAY)...
MODEL DIVERGENCE IS LARGER THAN TYPICAL THROUGH THE LONG TERM
PORTION OF THE FORECAST...WITH RELATIVELY LARGE DISCREPANCIES
NOTED BETWEEN THE 00Z GFS AND 00Z EC. GFS ENSEMBLE 500 MB HEIGHT
STANDARD DEVIATIONS ARE LARGE OVER UTAH FROM 00Z FRIDAY THROUGH
00Z SATURDAY...INDICATING DISPERSION OF THE MEMBERS AS TO WHETHER
THE TROUGH WILL HANG FURTHER WEST LIKE THE OPERATIONAL GFS OR MORE
PROGRESSIVE...REMINISCENT OF THE 00Z EC.

THAT SAID...SHORTWAVE RIDGING IS EXPECTED TO DEVELOP IN THE WAKE OF
THE TROUGH. DEPENDING ON HOW QUICKLY THE TROUGH DEPARTS THE
AREA...RIDGING SHOULD ALLOW FOR A WARM DAY FRIDAY BUT THE EC WOULD
FAVOR A WARMER HIGH THAN THE GFS.

ANOTHER WEAKENING TROUGH WILL MOVE ACROSS THE AREA SATURDAY INTO
SUNDAY. GIVEN THE MODEL TO MODEL INCONSISTENCIES MENTIONED
ABOVE...DID NOT LEAN TOWARD A PARTICULAR MODEL. ADJUSTED POPS A BIT
CLOSER TO CLIMO GIVEN UNCERTAINTY AND THE DISTURBANCES MOVING
THROUGH THE AREA. BOTH MODELS INDICATE THE POSSIBILITY OF A RATHER
LARGE STORM SOMETIME DURING THE WEEK OF THE 20TH. WHILE TOO FAR OUT
TO HAVE ANY REAL CONFIDENCE...SOMETHING TO WATCH OVER THE NEXT WEEK.

&&

.AVIATION...WINDS AT THE SLC TERMINAL WILL REMAIN FROM THE NORTH
THROUGH 04Z-06Z. VFR CONDITIONS WILL PREVAIL.

&&

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

$$

SHORT TERM...ROGOWSKI
LONG TERM/AVIATION...HOSENFELD

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)



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