Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 182324
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
624 PM CDT THU SEP 18 2014

.UPDATE...
ISSUED AT 619 PM CDT THU SEP 18 2014

MAIN CHALLENGE THIS EVENING WILL BE RAIN CHANCES IN STRONG WARM
ADVECTION ZONE AHEAD OF APPROACHING TROUGH. CURRENTLY SOME WEAK
ECHOES ACROSS THE NORTHERN VALLEY. SOME ISOLD LTG STRIKES EARLIER
BUT CONVECTION HAS OUT RUN WHAT INSTABILITY THERE WAS. HAVE ISOLD
SPRINKLE MENTION INTO EARLY EVENING FOR THIS AREA. WILL MONITOR
TRENDS ELSEWHERE THROUGH THE EVENING. NO OTHER CHANGES.

&&

.SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT)
ISSUED AT 339 PM CDT THU SEP 18 2014

CHALLENGE FOR THIS FORECAST INCLUDE POPS PLACEMENT WITH ACTIVE
PERIOD SETTING UP FOR THE NEXT 48 HOURS. MODELS HANDLING GENERAL
SYNOPTIC FEATURES WELL WITH THE NORMAL SPREAD IN CONVECTIVE QPFS
GENERATED OVER THE NEXT COUPLE DAYS.

THIS AFTERNOON INTO THE OVERNIGHT PERIOD WILL CONTINUE TO SEE LOW
LEVEL JET BRINGING MOISTURE AND WARMER BLYR TEMPS TO THE AREA.
WITH WAA AND MOISTURE STREAMING INTO THE REGION MIXING WILL
OFFSET SUNDOWN AND ALLOW SFC WINDS TO STAY UP. LATER TONIGHT...
AROUND 9Z...HRRR/RAP/HOP-WRF ENSEMBLE BRING IN SOME CONVECTION
ACROSS THE CENTRAL VALLEY...WILL KEEP THE CHANCE OF SHRA AND
THUNDER.

BY FRIDAY 1.5 INCH PWATS WITH A SFC TROUGH AND WESTERLY WINDS
NOSE INTO THE WESTERN CWFA. THE MOISTURE/INSTABILITY COMBINED
WITH THE SLOW MOVING TROUGH AND ZONAL FLOW WILL ALLOW FOR THE
POTENTIAL FOR ANY WEAK PERTURBATION IN THE FLOW TO INITIATE SHOWER
AND THUNDERSTORMS. BEST CHANCE WILL BE ALONG THE TRACK OF THE SFC
LOW WHERE MODELS AGREEMENT IS DEPICTING IT ACROSS THE NORTHERN
VALLEY INTO NW MN.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 339 PM CDT THU SEP 18 2014

THE NEXT SHORT WAVE IS ESCORTED ON THE NOSE OF 300MB JET
SATURDAY. COLD CORE ALOFT WITH -20C ADVECTING IN AT 500MB WILL
BRING AFTERNOON SHOWERS AND THUNDER POTENTIAL...GIVEN THE CURRENT
TIMING BEST CHANCES WILL BE IN NW MN. WIND POTENTIAL IN ITS WAKE
IS A CONCERN ACROSS E ND AND RRV AS 30 TO 35 KTS OF NW WIND MAY
MIX TO NEAR 800MB.

EXTENDED PERIOD BEGINS WITH LONG WAVE RIDGE OVER PACIFIC NORTHWEST
WITH TROUGH OVER GREAT LAKES. NORTHWEST DRY FLOW INDICATED FOR THE
NORTHERN PLAINS AS THE UPPER PATTERN TRANSITIONS TO THE EAST THROUGH
THE MIDDLE OF THE WEEK. THIS WOULD PLACE RIDGE OVER FORECAST AREA
TUE/WED ACCOMPANIED BY ABOVE NORMAL TEMPS BY 5 TO 10 DEGREES. SOME
DISAGREEMENT BETWEEN GFS AND ECMWF ENTERS THE PICTURE BY LATER
WEDNESDAY WITH TROUGHINESS IN THE GFS AND MORE OF A CLOSED LOW FOR
THE ECMWF. EITHER OF THESE SOLUTIONS INTRODUCES LOW POPS TO THE
FORECAST DURING THIS TIME.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z FRIDAY EVENING)
ISSUED AT 619 PM CDT THU SEP 18 2014

KEPT CIGS/VSBY VFR OVERNIGHT. MOST MODEL GUIDANCE INDICATING SOME
MVFR PSBL IFR CIGS ACROSS THE SOUTH AND EAST IN THE THE AM AND
FOLLOWED GUIDANCE WITH CIGS IN LATE PERIODS.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...NONE.
MN...NONE.
&&

$$

UPDATE...VOELKER
SHORT TERM...JK
LONG TERM...WJB/JK
AVIATION...VOELKER






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