Area Forecast Discussion
Issued by NWS Grand Forks, ND

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FXUS63 KFGF 181155
AFDFGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND FORKS ND
655 AM CDT MON AUG 18 2014

.UPDATE...
ISSUED AT 655 AM CDT MON AUG 18 2014

STILL HAVE SOME AREAS OF FOG WITHIN THE LIGHT SOUTHERLY WIND
REGIME OVER WC MN AND LAKES COUNTRY...WHICH HAS BEEN LOCALLY DENSE
IN SPOTS. THERE SHOULD GRADUALLY BE IMPROVEMENT AS WINDS BECOME
WESTERLY. OTHERWISE...AREAS OF SHOWERS AND ISOLATED THUNDER HAVE
CONTINUED TO DEVELOP EARLY THIS MORNING. LOCALLY HEAVY RAINFALL IS
POSSIBLE WITH ANY OF THE STORMS THROUGH THE DAY.

&&

.SHORT TERM...(TODAY THROUGH TUESDAY)
ISSUED AT 340 AM CDT MON AUG 18 2014

EARLY AM WV IMAGERY SHOWS THE MAIN UPPER LOW PUSHING SOUTHEASTWARD
ACROSS MANITOBA. CONVECTION THAT FIRED LATE YESTERDAY HAS
WEAKENED...BUT SOME RE-DEVELOPMENT HAS OCCURRED OVERNIGHT AS THE
UPPER FORCING STRENGTHENS ASSOCIATED WITH THE UPPER LOW. WITH A
WEAK SFC TROUGH ACROSS THE REGION AND GENERALLY LIGHT WINDS...SOME
FOG HAS DEVELOPED...MOST NOTABLY IN WC MN. THE FOG HAS BEEN QUITE
DENSE TO THE SOUTHEAST OVER CENTRAL MN...SO A CONCERN OVER THE
NEXT FEW HOURS WILL BE FOG COVERAGE AND DENSITY IN THIS AREA.

THE MAIN CHALLENGE LATER IN THE DAY WILL BE PRECIP CHANCES. WITH
THE SFC TROUGH SLOWLY WORKING EAST AND THE UPPER LOW
SOUTHEASTWARD...EXPECT SOME SHOWERS AND THUNDER (ALTHOUGH SEVERE
IS NOT EXPECTED). THE NAM/GFS/ECMWF ALL INDICATE THE HIGHEST QPF
WILL BE ACROSS THE EASTERN CWA...CLOSER TO THE SFC TROUGH AND
STRONGEST UPPER FORCING THIS AFTERNOON. PWATS WILL BE AROUND 1.4
INCHES THIS AFTERNOON OVER THE EAST...SO THERE WILL BE SOME
HEAVIER DOWNPOURS IN SPOTS. CURRENT FORECAST TEMPS ARE IN THE
MID/UPPER 70S...BUT CLOUD COVER WILL PLAY A ROLE ON TEMP TRENDS
TODAY.

THE UPPER LOW WILL MOVE EAST ACROSS NORTHERN MINNESOTA TONIGHT.
MUCH OF THE AREA WILL DRY OUT OVERNIGHT...WITH SOME SHOWERS
PERSISTING MAINLY EAST OF THE VALLEY. WITH LIGHT WINDS AND NOT
MUCH CHANGE IN SFC MOISTURE...THERE COULD SOME FOG DEVELOPMENT
POTENTIALLY.

WEAK SFC RIDGING WILL SPREAD ACROSS THE REGION TUESDAY UNDERNEATH
SHORTWAVE RIDGING ALOFT. THE UPPER LOW ACROSS THE WESTERN GREAT
LAKES MAY BE CLOSE ENOUGH TO PROVIDE A FEW DIURNAL SHOWERS/STORMS
EAST OF THE VALLEY. WOULD ALSO EXPECT DIURNAL CU DEVELOPMENT TO BE
GREATEST IN THIS AREA. OTHERWISE...TUESDAY SHOULD BE A PLEASANT
DAY WITH LIGHT WINDS AND SEASONABLE TEMPS.

.LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY)
ISSUED AT 340 AM CDT MON AUG 18 2014

UPPER TROUGHING DEVELOPING OVER THE WESTERN US BY TUESDAY NIGHT WILL
AID IN SFC LOW PRESSURE DEVELOPMENT ACROSS THE HIGH PLAINS...WITH
SFC WINDS BECOMING SOUTHERLY DOWNSTREAM. THE GLOBAL MODELS DEPICT A
SHORTWAVE TROUGH LIFTING NORTHEASTWARD INTO THE N PLAINS ON
WEDNESDAY AS THE UPPER FLOW BECOMES SOUTHWESTERLY. THE
GEM/NAM/ECMWF ARE IN FAIRLY GOOD AGREEMENT WITH THE TIMING AND
POSITION OF THE WAVE...WHILE THE GFS IS FARTHER SOUTH. THE MODEL
CONSENSUS WOULD YIELD THE HIGHEST RAIN CHANCES LATE WED/WED NIGHT
WITHIN THE WARM...MOIST ADVECTION ZONE AHEAD OF THE WAVE. TEMPS
WILL CONTINUE NEAR AVERAGE FOR MID-WEEK.

00Z RUNS OF ECMWF/GEM/GFS ALL INDICATE A 500 MB TROUGH OVER WRN
CANADA INTO NRN ROCKIES.  SEVERAL SHORT WAVES WILL COME OUT OF THE
EASTERN PACIFIC INTO THE NRN ROCKIES AND THEN INTO NRN PLAINS IN THE
THURSDAY THROUGH SUNDAY PERIOD.  TIMING AND STRENGTH OF EACH WAVE IS
AS YOU SUSPECT VARIABLE RUN TO RUN AND MODEL TO MODEL.  BUT SOME
AGREEMENT IS THAT ONE SUCH WAVE AND RAIN MAKER WILL MOVE ACROSS
THURSDAY WITH ANOTHER SYSTEM FRI NIGHT INTO SATURDAY.  GRADUALLY
COOLER THRU THE PERIOD.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z TUESDAY MORNING)
ISSUED AT 655 AM CDT MON AUG 18 2014

TODAY WILL BE A CHALLENGING AVIATION FORECAST. THERE WILL BE
PERIODS OF SHOWERS AND THUNDERSTORMS...WHICH WILL DIMINSH THIS
EVENING. WITH THE SCATTERED NATURE OF THE PRECIPITATION...TIMING
OF SHOWERS/STORMS AT ANY GIVEN SITE IS UNCERTAIN. THERE ARE ALSO
SOME AREAS OF FOG AND IFR CIGS GENERALLY ALONG AND EAST OF THE
RRV THIS MORNING. GENERALLY EXPECT GRADUALLY IMPROVING VSBYS AND CIGS
THROUGH THE MORNING...ESPECIALLY AS WINDS TURN MORE WESTERLY AND
NORTHWESTERLY DURING THE DAY. CONFIDENCE IS RATHER LOW ON HOW
QUICKLY THIS WILL OCCUR.

&&

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

$$

UPDATE...MAKOWSKI
SHORT TERM...MAKOWSKI
LONG TERM...MAKOWSKI/RIDDLE
AVIATION...MAKOWSKI





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