Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 011748
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
1248 PM CDT SAT AUG 1 2015

.UPDATE...
ISSUED AT 1248 PM CDT SAT AUG 1 2015

SPC DID EXTEND THE MARGINAL SEVERE RISK INTO SOUTHEAST NORTH
DAKOTA...WHICH SEEMS APPROPRIATE. AT 17Z...DEWPOINT VALUES AHEAD
OF A WEAK SFC LOW/CONVERGENCE AREA ARE POOLING INTO THE MID-UPPER
60S...WHICH HAD LED TO MLCAPE 2000-2500 J/KG ACROSS SOUTH CENTRAL
NORTH DAKOTA...WHICH WILL SLOWLY PROPAGATE EASTWARD. THE CAP IS
STILL STRONG...BUT AS TEMPERATURES APPROACH 90F THIS CAP WILL
ERODE. CURRENT THINKING IS THAT THERE WILL BE A BRIEF WINDOW OF
OPPORTUNITY FOR STORM DEVELOPMENT ACROSS THE SOUTHERN FA DURING
THE LATE AFTERNOON HOURS. STORMS SHOULD QUICKLY DIMINISH THIS
EVENING CONSIDERING CONVECTIVE TEMPS NEAR 90F. ANY ISOLD STORM
THAT DOES DEVELOP WILL HAVE THE POTENTIAL TO BE SEVERE GIVEN 0-6KM
SHEAR 35-40 KNTS ALONG WITH THE MODERATE INSTABILITY.

AN AREA OF STORMS WILL AFFECT THE NORTHERN FA WITH THE PASSAGE OF
ANOTHER UPPER LEVEL WAVE TONIGHT. ALTHOUGH DEEP LAYER SHEAR WILL
BE VERY STRONG (60+ KNOTS)...INSTABILITY SHOULD BE VERY WEAK. A
STRONGER WIND GUST MAY BE POSSIBLE GIVEN 500MB WINDS AOA 50
KNOTS.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 356 AM CDT SAT AUG 1 2015

NORTHWEST-SOUTHEAST ORIENTATED UPPER LEVEL JET ESSENTIALLY REMAINS
OVER THE NORTHEAST ZONES HOWEVER JET DOES OSCILLATE NORTHEAST OF THE
FORECAST AREA THEN BACK OVER THE NORTHEAST ZONES AS SHORT WAVES MOVE
THROUGH THE FLOW. UPPER LEVEL TROUGH OVER NORTHERN MAN WILL ROTATE
ACROSS ONTARIO SAT NIGHT ELSEWHERE WATER VAPOR LOOP INDICATED SHORT
WAVES OVER CENTRAL SASK AND ANOTHER OVER ALTA/BC BORDER. BC SHORT
WAVE WILL DROP SOUTH ACROSS THE GREAT LAKE STATES SUN AND AMPLIFY
THE UPPER TROUGH EAST OF THE AREA. RIDGE BUILDING COMMENCES IN THE
WESTERN US SUN AND SHIFTS INTO THE HIGH PLAINS BY 84 HOURS.

PRECIPITABLE WATER INCREASES OVER AN INCH IN THE SOUTH WITH SURFACE
TROUGH MOVING THROUGH. SHOWALTERS BECOME NEGATIVE OVER THE SOUTHERN
ZONES THIS AFTERNOON AND EVENING WITH LOW LEVEL MOISTURE. SHOWALTERS
ALSO BECOME NEGATIVE IN THE NORTH THIS AFTERNOON AND OVERNIGHT WITH
APPROACHING SHORT WAVE. PRECIPITABLE WATER ALSO INCREASES OVER AN
INCH FROM THE NORTH WITH TROUGH MOVING ACROSS SOUTHERN CANADA.

WEAK SURFACE LOW OVER THE WESTERN DAKOTAS WILL MOVE INTO MN AND
DISSIPATE THIS EVENING. ANOTHER SURFACE LOW OVER SOUTHERN ALTA WILL
MOVE INTO MN BY 12Z SUN. THEN HIGH PRESSURE FOLLOWS FOR THE REST OF
THE PERIOD.


.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 356 AM CDT SAT AUG 1 2015

FOR TUESDAY THROUGH FRIDAY...LONG RANGE GFS/ECMWF HAVE REMAINED IN
FAIR AGREEMENT IN SHOWING UPPER TROUGH OVER ONTARIO MOVING EAST AND
A WESTERLY FLOW AT 500 MB SETTING UP OVER THE NRN PLAINS/SRN CANADA
MID TO LATE WEEK.  WITH THIS WILL COME A COUPLE OF DISTURBANCES WITH
THUNDERSTORM CHANCES.   00Z ECMWF HAS A TAD WETTER PATTERN VS A BIT
DRIER 00Z GFS.  BLENDED MODEL SOLN HAVE POPS IN THE AREA WED-FRI AND
LEFT THEM FOR NOW.  THE MAIN UPPER HEAT RIDGE WILL REMAIN OVER THE
SRN PLAINS AND AREA WILL BE A TAD BELOW NORMAL TEMP REGIME THRU THE
PD.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 1248 PM CDT SAT AUG 1 2015

TAFS FOR THE 18Z UPDATE REFLECT MODEST THUNDERSTORM PROBABILITIES
ACROSS NRN RED RIVER VALLEY AND NRN MN LATE TONIGHT.

FIRST...THERE MAY BE SOME THUNDERSTORMS SOUTH AND EAST OF KFAR THIS
AFTERNOON/EVENING AHEAD OF THE COLD FRONT. PROBABILITIES HAVE
INCREASED SLIGHTLY FOR KFAR TO SEE AN AFTERNOON TS CLOSE TO THE
TERMINAL. LAST FEW HRRR MODEL RUNS HAVE HAD TS ACTIVITY NEAR KFAR.
HAVE INCLUDED VCTS AT 23Z FOR NOW.

LATE TONIGHT...A COLD FRONT WILL PUSH THROUGH THE AREA AND MODELS
INDICATE THERE MAY BE SOME THUNDERSTORM ACTIVITY PUSHING
SOUTHEASTWARD AFTER MIDNIGHT. EXPECTING WEAKER THUNDERSTORMS
COMPARED TO THIS AFTERNOONS ACTIVITY NEAR KFAR. HAVE LEFT KDVL
AND KFAR OUT OF THE VCTS MENTION AS THEY WILL BE ON THE SOUTHERN
AND WESTERN EDGE OF THE ACTIVITY.

&&

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

$$

UPDATE...TG
SHORT TERM...HOPPES
LONG TERM...RIDDLE
AVIATION...KNUTSVIG


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