Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 201449
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
949 AM CDT SUN JUL 20 2014

.UPDATE...
ISSUED AT 949 AM CDT SUN JUL 20 2014

PRETTY QUIET ACROSS THE FA NOW BUT HUMIDITY NOTICEABLY HIGHER THIS
MORNING AS SFC DEW POINTS ARE IN THE MID TO UPPER 60S. THERE IS
STILL A SMALL PATCH OF FOG/HAZE AROUND KPKD WHICH SHOULD ERODE IN
THE NEXT HOUR OR SO. LOOKING TO BE A HOT ONE TODAY WITH TEMPS IN
THE 90S FOR MOST AREAS. OTHER QUESTION WILL BE TSTM CHANCES.
NOT A HIGH CONFIDENCE FORECAST AT THIS POINT DUE TO THE WIDE
VARIETY IN MODEL SOLUTIONS. THE SAME MODELS WERE ALSO DEVELOPING A
LINE OF WEAKER CONVECTION OVER THE FA IN THE 08Z-12Z SUNDAY TIME
FRAME (EARLY THIS MORNING) WHICH NEVER MATERIALIZED. LOTS OF
MOISTURE AND INSTABILITY AROUND THIS AFTERNOON BUT THE LIFT SOURCE
IS A LITTLE MORE QUESTIONABLE. UPPER JET ALONG THE US/CANADIAN
BORDER FOCUSES MORE INTO THE MANITOBA LAKES AREA THIS AFTERNOON.
700MB TEMPS ALSO RISE TO +10C ALONG AND SOUTH OF THE HIGHWAY 200
CORRIDOR BY 00Z MON. THERE IS SOME WEAK CONVERGENCE ALONG A SFC
TROUGH THIS AFTERNOON BUT MODELS ARE EVEN WEAKER WITH THIS FEATURE
TODAY. SPC MAINTAINS A SLIGHT RISK FOR SEVERE TSTMS OVER ALL OF
THE NORTHWEST QUARTER OF MN BACK INTO THE SOUTHERN RED RIVER
VALLEY. WILL THEREFORE MAINTAIN PREVIOUS FORECAST WHICH HAD
THUNDER CHANCES OVER THIS AREA...BUT WILL PUSH BACK THE ONSET TIME
MORE TO MID TO LATE AFTERNOON. LATEST MODEL GUIDANCE NOT HELPING
TOO MUCH WITH THE 12Z NAM DEVELOPING ALL THUNDER JUST TO THE EAST
OF THE FA AND THE LATEST HIGH RESOLUTION SOLUTIONS OVER JUST THE
EXTREME EASTERN FA. WILL CONTINUE TO LOOK OVER NEW GUIDANCE AS IT
COMES IN.

&&

.SHORT TERM...(TODAY THROUGH MONDAY)
ISSUED AT 338 AM CDT SUN JUL 20 2014

CHALLENGES INCLUDE THUNDERSTORM CHANCES AND SEVERE THREAT THIS
AFTERNOON/EVENING AND AGAIN MONDAY NIGHT. HIGH RESOLUTION/GLOBAL
MODELS IN GOOD AGREEMENT. WILL USE A RAP/HRRR BLEND THROUGH 00 UTC
TONIGHT AND A GLOBAL ENSEMBLE THEREAFTER.

FOR TODAY...SFC TROUGH CURRENTLY ACROSS THE WESTERN DAKOTAS WILL
MOVE EAST AND SET-UP ALONG A LINE FROM HALLOCK TO ABERDEEN BY 18
UTC. STRONG MOISTURE ADVECTION AND DIABATIC HEATING AHEAD OF THIS
BOUNDARY WILL RESULT IN AFTERNOON MUCAPE UP TO 3000 J/KG. PRIMARY
FORCING ALOFT REMAINS NORTH OF THE CANADIAN BORDER...BUT BULK
SHEAR UP TO 30 KTS STILL POSSIBLE. ADDED SEVERE MENTION ACROSS
PORTIONS OF NORTHWEST MN LATE AFTERNOON/EARLY EVENING TO THE WX
GRIDS TO COINCIDE WITH SPC SLIGHT RISK AREA. PRIMARY THREATS ARE
LARGE HAIL AND DAMAGING WIND. AREAS WEST OF THE SFC TROUGH WILL
REMAIN DRY THROUGH THE DAY.

IN ADDITION...TEMPS WILL SOAR INTO THE UPPER 80S TO LOWER 90S
TODAY. COMBINED WITH DEW POINTS RISING INTO THE LOWER 70S...HEAT
INDEX VALUES COULD FLIRT WITH THE UPPER 90S. NO PLANS FOR A HEAT
ADVISORY AS WORST CONDITIONS SHOULD REMAIN BELOW 100 DEGREES AND
BE SHORT-LIVED.

MONDAY WILL SEE A BATTLE BETWEEN SFC HIGH PRESSURE ACROSS THE
SOUTHERN CANADIAN PRAIRIES AND DEVELOPING LOW PRESSURE ACROSS SD
WITH A WELL-DEFINED FRONTAL BOUNDARY SOMEWHERE ACROSS THE SOUTHERN
FORECAST AREA. TEMPS SOUTH OF THIS BOUNDARY WILL RISE ONCE AGAIN
INTO THE LOWER 90S WITH POSSIBLE HEAT ADVISORY CONDITIONS
DEVELOPING BY MID-LATE AFTERNOON. FARTHER NORTH TEMPS WILL BE A
BIT COOLER...TOPPING OUT IN THE MID TO UPPER 80S. SOME AFTERNOON
CONVECTION IS POSSIBLE ACROSS THE CENTRAL AND NORTHERN FORECAST
AREA IN LESS CAPPED MID-LEVEL WARM AIR ADVECTION REGIME...BUT MOST
OF THE DAY SHOULD REMAIN DRY.

.LONG TERM...(MONDAY NIGHT THROUGH SATURDAY)
ISSUED AT 338 AM CDT SUN JUL 20 2014

ATTENTION QUICKLY TURNS TO MONDAY NIGHT WHEN MOST MODELS ARE
HINTING AT SOME KIND OF CONVECTIVE COMPLEX ROLLING ACROSS THE
NORTHERN PLAINS. A HIGHLY UNSTABLE ENVIRONMENT WITH MLCAPE VALUES
UP TO 5000 J/KG WILL DEVELOP TO THE NORTH AND EAST OF THE SFC LOW.
INCREASING WESTERLIES ALOFT FROM AN APPROACHING 500 HPA WAVE WILL
HELP TRIGGER CONVECTIVE INITIATION. SHEAR PROFILES INITIALLY
SUPPORT SCATTERED MULTICELLS/SUPERCELLS...BUT SHOULD QUICKLY GROW
UPSCALE INTO A MCS WITH THE PRIMARY THREAT BEING DAMAGING WIND.
ADDED SEVERE MENTION TO THE WX GRIDS MONDAY NIGHT MAINLY ALONG AND
SOUTH OF THE I-94/HWY 10 CORRIDOR.

TUESDAY WILL BE DRIER AND COOLER WITH SFC HIGH PRESSURE BUILDING
ACROSS THE REGION. TEMPS WILL TOP OUT IN THE MID 70S TO LOWER 80S.

WEDNESDAY-SATURDAY...UPPER RIDGING ACROSS THE ROCKY MOUNTAINS
WILL EVENTUALLY BE KNOCKED DOWN BY A STRONG UPPER LOW BY LATER IN
THE WEEK. THE DETAILS REGARDING THE EXACT TRACK/SPEED OF THIS
UPPER LOW ARE STILL UNCERTAIN...BUT THE GENERAL IDEA IS THAT THE
PERIOD WILL START OFF DRY...WITH THUNDER CHANCES INCREASING BY
LATER ON THURSDAY OR FRIDAY. TEMPERATURES WILL BE NEAR NORMAL
VALUES...WITH EXACT VALUES DEPENDENT ON THE LOCATION OF THE UPPER
LOW.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)
ISSUED AT 702 AM CDT SUN JUL 20 2014

EXPECT VFR CONDITIONS TO PERSIST AT ALL TAF AIRFIELDS THROUGH 12
UTC MONDAY. DID ADD VCTS AT KBJI BETWEEN 00 AND 04 UTC...BUT
TIMING AND LOCATION OF CONVECTION STILL TOO UNCERTAIN TO INCLUDE
PREDOMINANT THUNDER. SOUTHERLY WINDS...GUSTING AT TIMES TO 20
KTS...WILL SHIFT TO THE WEST-SOUTHWEST AS SFC TROUGH MOVES ACROSS
THE REGION. WINDS TO BECOME LIGHT AND VARIABLE OVERNIGHT WITH
BUILDING HIGH PRESSURE.

&&

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

$$

UPDATE...GODON
SHORT TERM...ROGERS
LONG TERM...ROGERS/TG
AVIATION...ROGERS







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